JP2003073465A - Method for producing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester containing little foreign matter, giving a blow molding, etc., excellent in transparency and flavor characteristic, and hardly generating mold stain at the molding of a molded body, and to provide a method for producing a polyester causing less rising of filtering pressure of a filter. SOLUTION: This method for producing a polyester comprises the steps of (a) producing an oligomer by esterification or ester interchange of a dicarboxylic acid including terephthalic acid or an ester formable derivative thereof and a glycol including ethylene glycol or an ester formable derivative thereof, (b) melt polycondensing the oligomer, (c) chipping the melt polycondensed polyester while cooling it using cooling water satisfying a specified range, and (d) solid polymerizing the melt polycondensed polyester with intrinsic viscosity of 0.30 to 0.80 dL/g.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a bottle, a packaging material such as a film and a sheet, and a tire core.
The present invention relates to a method for producing polyester used for fibers for industrial materials such as cords and the like. More specifically, a polyester that contains almost no foreign matter and has excellent transparency and a molded article that does not give off-flavors or odors to its contents (good flavor), a mold for molding the molded article The present invention relates to a method for producing a polyester which is less likely to be soiled and a polyester which is less likely to be clogged with a filter during film formation and spinning and has improved operability.

[0002]

BACKGROUND OF THE INVENTION Polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier property, so that it is especially used for filling beverages such as juices, soft drinks, carbonated drinks, packaging films and audio. It is most suitable as a material for video films and is used in large quantities. It is also used in large quantities on a global scale as an industrial material such as clothing fibers and tire cords.

Polyesters generally contain a by-product, acetaldehyde. If the content of acetaldehyde in the polyester is high, the content of acetaldehyde in the container and other packaging materials formed from this will also be high, affecting the flavor and odor of the beverage filled in the container, etc. . Therefore, various measures have been conventionally taken to reduce the acetaldehyde content in the polyester, and a typical method is solid-phase polymerization of the melt polycondensed polyester.

Such a polyester is supplied to a molding machine such as an injection molding machine to mold a preform for a hollow molded body, the preform is inserted into a mold having a predetermined shape, stretch blow molding is performed, and then a bottle body is formed. It is general that a part is heat-treated (heat set) to be molded into a hollow molded container, and if necessary, a bottle cap is heat-treated (crystallized cap).

After completion of melt polycondensation, the melt polycondensed polyester is extruded from the pores and made into chips while being cooled with cooling water. Since it is disadvantageous in terms of cost to use distilled water as cooling water in the chip forming step, it is common to use industrial water that is a simple treatment of water from rivers, groundwater, drainage, and the like. However, when the cooling treatment using industrial water, there is often a problem that the flavor and aroma of the content of the obtained molded container becomes very bad,
This solution was awaited. In such a case, crystallization of the obtained polyester at the time of molding is too early, resulting in a bottle with poor transparency, and shrinkage of the plug part due to crystallization of the plug part does not fall within the specifications. There was also the problem of capping failure.

According to the results of studies by the present inventors, it was found that, in the chipping process, organic particles and organic compounds originating in nature-derived bacteria, bacteria, etc. contained in industrial water, and spoiled plants and animals. It has been found that when the content of the above is a certain value or more, these substances are adsorbed and permeated on the surface of the polyester chip, and have an adverse effect on the flavor and odor of the contents of the molding container. Further, when the content of metal-containing substances such as sodium, magnesium, calcium, silicon (silicic acid) contained in industrial water exceeds a certain value, metal-containing substances such as oxides or hydroxides of these metals It was found that it adheres to and permeates polyester chips, promotes crystallization during molding, and becomes a bottle with poor transparency. Further, since the metal-containing substance adheres to the cooling tank in the chip forming process, the cooling water pipe, the return pipe for draining water after cooling, and the like as a scale, there arises a problem that it is difficult to clean them. In particular, the inclusion of sodium does not cause scale, but sodium ions permeate into the surface layer of the chip, and crystallization proceeds with the sodium ions as nuclei, which is a major factor for whitening the bottle.

The metal-containing substance attached to the surface of the chip in the chip forming step and brought into the solid-state polymerization reaction device is fixed to the vessel wall of the solid-state polymerization device together with a part of the surface layer of the polyester chip. However, this becomes a scale with a high metal content and adheres to the vessel wall by heating for a long time at a high temperature of about 170 ° C. or higher. Then, it sometimes peels off and mixes into the polyester chip, and becomes a foreign substance in a molded article such as a bottle, which may reduce the commercial value.

When manufacturing a film or fiber,
There is also a problem in that the above-mentioned scale is clogged with the molten polymer filtration filter during spinning or film formation, the filtration pressure of the filter increases sharply, and the operability and productivity deteriorate.

[0009]

DISCLOSURE OF THE INVENTION The present invention is to solve the problems of the prior art, contains almost no foreign matter,
The present invention relates to a method for producing a polyester having a hollow molded article having excellent transparency and flavor, which is less likely to cause mold stains during molding of the molded article, and a polyester having a small increase in filtration pressure of a filter.

[0010]

In order to achieve the above object, a method for producing a polyester of the present invention comprises a dicarboxylic acid containing terephthalic acid or an ester-forming derivative thereof and a glycol containing ethylene glycol or an ester thereof. A low-polymer production step (a) of esterifying or transesterifying with a forming derivative, a melt polycondensation step (b) of melt-polycondensing the low-polymer obtained in the low-polymer production step, and the melt. The molten polycondensed polyester obtained in the polycondensation step has the following sodium content (N), magnesium content (M), silicon content (S) and calcium content (C): Chipping step (c) of chipping while cooling with cooling water that satisfies at least one of (4), N ≤ 1.0 (ppm) (1) M ≤ 0.5 (ppm) ( ) S ≤ 2.0 (ppm) (3) C ≤ 1.0 (ppm) (4) and a melt weight having an intrinsic viscosity of 0.30 to 0.80 deciliter / gram, which is obtained in the chipping step. A solid-state polymerization step (d) of solid-phase polymerizing a condensed polyester, the method for producing a polyester.

In this case, the total oxygen consumption (TOD) of the introduced water introduced from the outside of the system to the chip forming process is 10
It can be 0 ppm or less.

In this case, when the water obtained by mixing at least a part of the water discharged from the chipping step (c) with fresh introduced water from outside the system is used as the cooling water in the chipping step (c). The content of ethylene glycol, the content of monohydroxyethyl terephthalate, and the content of bishydroxyethyl terephthalate in the cooling water can be maintained at 100 ppm or less, respectively.

In this case, at least water treated by an ion exchange device can be used as the cooling water in the chip forming step (c).

In this case, the surface temperature S of the molten polycondensed polyester which is cooled with the cooling water in the chipping step (c) being 7 to 50 ° C. and the cooling water amount V (cm ³ / sec). (Cm ² / sec) ratio (V / S)
However, it can be made into chips under the condition that the following (5) is satisfied. 0.1 ≦ (V / S) ≦ 2.0 (5)

In this case, an intermediate step (e) between the chip forming step (c) and the solid phase polymerization step (d), or the solid phase polymerization step (d) and the solid phase polymerization step (d). The removal step (h) for removing fines and / or film-like substances may be added to at least one intermediate step of the intermediate step (g) and the subsequent step (f) installed after the step (b). it can.

In this case, the fine content of the melt polycondensed polyester supplied in the solid phase polymerization step (d),
Content of at least one of the film content, or the total content of the fine content and the film content, or the fine content of the solid-phase polymerized polyester supplied in the subsequent step (f), the film Content, or at least one of the total content of the fine content and the film content, is 5
It can be up to 00 ppm.

Here, fine means JIS-Z8801.
According to JIS means fine powder of polyester that has passed through a sieve having a mesh size of 1.7 mm, and a film-like material remains on a sieve having a mesh size of 5.6 mm according to JIS-Z8801. Of polyester, it means a film-like material after two or more chips are fused or the chip-like material cut into pieces larger than the normal shape is removed, and the content thereof is measured by the following measuring method. .

In this case, the subsequent step (f)
Can be at least one of a contact treatment step with water and a thermoplastic resin blending step.

In this case, in at least one of the melt polycondensation step (b), the chip forming step (c), the solid phase polymerization step (d), the post step (f), and the fines removing step (h). As the gas that comes into contact with the polyester, it is possible to use a gas introduced from outside the system, in which the number of particles having a particle size of 0.3 to 5 μm is 1,000,000 particles / cubic foot or less.

In this case, the polyester obtained by injection molding has an intrinsic viscosity of 0.60 to 2.00 deciliter / gram, an acetaldehyde content of 10 ppm or less, and a cyclic trimer content of 0.5% by weight or less. The number of spherulites generated when the formed molded plate is crystallized at elevated temperature is 1 × 10 ⁹ to 1
The polyester may be in the range of 5 × 10 ⁹ pieces / m ² .

Here, the number of spherulites formed when the crystallization is carried out at elevated temperature means the number of spherulites measured by the method described later.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the method for producing a polyester of the present invention will be specifically described below. The polyester according to the present invention is a polyester whose main repeating unit is ethylene terephthalate, preferably a linear polyester containing 80 mol% or more of ethylene terephthalate units, more preferably 85 mol% or more, and particularly preferably 90 mol%. % Linear polyester.

The dicarboxylic acid as a copolymerization component used when the polyester is a copolymer is
Aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid and their functional derivatives, p-oxybenzoic acid, oxycaproic acid, etc. Oxyacids and their functional derivatives, adipic acid, sebacic acid, succinic acid, glutaric acid, dimer acids and other aliphatic dicarboxylic acids and their functional derivatives, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids and their functional compounds Examples thereof include derivatives.

The glycol as a copolymerization component used when the polyester is a copolymer includes diethylene glycol, trimethylene glycol, tetramethylene glycol, neopentyl glycol and the like. Aliphatic glycols, alicyclic glycols such as cyclohexane dimethanol, polyalkylene glycols such as polyethylene glycol and polybutylene glycol, and bisphenols.
And aromatic glycols such as alkylene oxide adducts of bisphenol A and bisphenol A.

Further, as the polyfunctional compound as a copolymerization component used when the polyester is a copolymer, examples of the acid component include trimellitic acid and pyromellitic acid. Examples of the component include glycerin and pentaerythritol. The amount of the above copolymerization component used should be such that the polyester maintains a substantially linear shape. Further, a monofunctional compound such as benzoic acid or naphthoic acid may be copolymerized.

The method for producing a polyester of the present invention is a direct esterification in which terephthalic acid, ethylene glycol and, if necessary, other copolymerization components are directly reacted to distill off water to effect esterification, and then polycondensate under reduced pressure. Law, or
Melt polycondensation polyester prepared by reacting dimethyl terephthalate with ethylene glycol and optionally other copolymerization components to distill off methyl alcohol for transesterification and then polycondensation under reduced pressure. Of the polyester, followed by solid-state polymerization to increase the intrinsic viscosity and decrease the acetaldehyde content and the like. In order to accelerate crystallization before solid-phase polymerization, the molten polycondensed polyester may be adsorbed with moisture and then crystallized by heating, or steam may be directly blown onto the polyester chips to be crystallized by heating.

The low polymer producing step (a) and the melt polycondensation step (b) may be constituted by a batch reactor or a continuous reactor. In any of these methods, the esterification or transesterification reaction and the melt polycondensation reaction are
It may be performed in stages, or may be divided into multiple stages. The solid phase polymerization step (d) may be composed of a batch reaction apparatus or a continuous reaction apparatus, like the above-mentioned steps. The low polymer production step (a), the melt polycondensation step (b) and the solid phase polymerization step (d) may be operated continuously or separately. Generally, the low polymer production step (a) and the melt polycondensation step (b) are connected and operated.

An example of a preferable continuous production method will be described below using polyethylene terephthalate as an example.

A raw material containing the above-mentioned terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative is subjected to an esterification reaction or a transesterification reaction in the low polymer production step (a) to obtain a low weight. Be united.

When the low-condensation product is produced by the esterification reaction, 1.02 to 1.5 mol, preferably 1.03, relative to 1 mol of terephthalic acid or its ester derivative.
~ 1.4 mol slurry containing ethylene glycol
Is continuously supplied to the esterification reaction step.

Such an esterification reaction may be carried out in one step or in multiple steps. A case of performing the operation in multiple stages will be described. In the esterification reaction, water or alcohol produced by the reaction is used in a rectification column under a condition in which ethylene glycol is refluxed using a multistage apparatus in which at least two esterification reactors are connected in series. Perform while removing to the outside. The temperature of the first stage esterification reaction is 240 to 270 ° C, preferably 245 to 265 ° C,
The pressure is 0.02 to 3 kg / cm ² G, preferably 0.0
It is 5 to ² kg / cm ² G. The temperature of the final stage esterification reaction is usually 250 to 280 ° C, preferably 255 to 280 ° C.
275 ° C, pressure is usually 0-1.5 kg / cm
² G, preferably 0 to 1.3 kg / cm ² G. When it is carried out in three or more stages, the reaction conditions for the esterification reaction in the intermediate stage are those between the reaction conditions of the first stage and the reaction conditions of the final stage. The increase in the reaction rate of these esterification reactions is preferably distributed smoothly at each stage. Finally, it is desirable that the esterification reaction rate reaches 90% or more, preferably 93% or more. A low polycondensate having a molecular weight of about 500 to 5000 is obtained by these esterification reactions.

When terephthalic acid is used as a raw material, the above esterification reaction can be carried out without a catalyst by the catalytic action of terephthalic acid as an acid, but it may be carried out in the presence of a polycondensation catalyst.

Further, tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine, tetraethylammonium hydroxide, tetra-hydroxide.
When quaternary ammonium hydroxide such as n-butylammonium or trimethylbenzylammonium hydroxide and a basic compound such as lithium carbonate, sodium carbonate, potassium carbonate or sodium acetate are added in a small amount, the main component of polyethylene terephthalate is obtained. It is preferable because the ratio of the dioxyethylene terephthalate component unit in the chain can be maintained at a relatively low level (5 mol% or less based on the total diol component).

When the low polycondensate is produced by the transesterification reaction, 1.1 to 1.6 mol, preferably 1.2 to 1.5 mol of ethylene glycol is used with respect to 1 mol of dimethyl terephthalate. A solution containing benzene is prepared and continuously supplied to the transesterification reaction step.

In the transesterification reaction, the methanol produced by the reaction is subjected to rectification in a rectification column under the condition that ethylene glycol is distilled off using a device in which 1 to 2 transesterification reactors are connected in series. Perform it while removing it outside the system. The temperature of the first-stage transesterification reaction is 180 to 250 ° C, preferably 200 to 240 ° C. The temperature of the final stage transesterification reaction is usually 230 to 270 ° C., preferably 24.
0 to 265 ° C., Zn as an ester exchange catalyst,
Fatty acid salts such as Cd, Mg, Mn, Co, Ca and Ba,
Carbonate, Pb, Zn, Sb, Ge oxide or the like is used. Due to these transesterification reactions, the molecular weight is about 200-500.
A low polymer is obtained.

As the starting material dimethyl terephthalate, terephthalic acid or ethylene glycol, virgin dimethyl terephthalate derived from paraxylene, ethylene glycol derived from terephthalic acid or ethylene, and used PE are used.
A recovered raw material such as dimethyl terephthalate, terephthalic acid, bishydroxyethyl terephthalate or ethylene glycol recovered from a T bottle by a chemical recycling method such as methanol decomposition or ethylene glycol decomposition can also be used as at least a part of the starting material. It goes without saying that the quality of the recovered raw material must be refined to the purity and quality according to the purpose of use.

Next, the low polymer thus obtained is heated under reduced pressure in the presence of a polycondensation catalyst to a temperature not lower than the melting point of the polyester obtained, and the glycol produced at this time is distilled out of the system. It is supplied to the melt polycondensation step (b) for polycondensation.

The polycondensation reaction in the melt polycondensation step (b) may be carried out in one stage or in multiple stages. A case of performing the operation in multiple stages will be described. The polycondensation reaction condition is that the reaction temperature of the first stage polycondensation is 250 to 290.
℃, preferably 260-280 ℃, the pressure is 500
~ 20 Torr, preferably 200-30 Torr,
The temperature of the polycondensation reaction in the final stage is 265 to 300 ° C, preferably 275 to 295 ° C, and the pressure is 10 to 0.1T.
orr, preferably 5 to 0.5 Torr. When the polycondensation reaction is carried out in three or more steps, the reaction conditions for the intermediate polycondensation reaction are those between the reaction conditions of the first stage and the reaction conditions of the final stage. The degree of increase in intrinsic viscosity reached in each of these polycondensation reaction steps is preferably distributed smoothly.

The polycondensation reaction is carried out using a polycondensation catalyst.
As the polycondensation catalyst, a compound of Ge, Sb, Ti, or Al is used, and Ge compound and Ti compound, Ge
It is also convenient to use mixed catalysts of compounds and Al compounds, Sb and Ti compounds, Sb and Ge compounds. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like.

As the Ge compound, amorphous germanium dioxide, crystalline germanium dioxide powder or a slurry of ethylene glycol, a solution of crystalline germanium dioxide dissolved in water by heating, or ethylene glycol added thereto and heat treated A solution obtained by heating and dissolving germanium dioxide in water or an ethylene glycol-containing solution is used to obtain the polyester used in the present invention.
It is preferable to use a solution which has been heated by adding a solvent. These polycondensation catalysts can be added during the esterification process. When a Ge compound is used, the amount used is 10 to 150 ppm, preferably 13 to 100 ppm, and more preferably 15 to 70 p, as the Ge residual amount in the produced polymer.
pm.

Examples of the Ti compound include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate and tetra-n-butyl titanate, and their partial hydrolysis. Examples thereof include titanyl oxalate, titanyl ammonium oxalate, sodium titanyl oxalate, potassium titanyl oxalate, titanyl calcium oxalate, titanyl oxalate compounds such as strontium titanyl oxalate, trimellitic acid titanium, titanium sulfate, titanium chloride and the like. The Ti compound is a formed polymer.
It is added so that the remaining amount of Ti in it is in the range of 0.1 to 10 ppm. Examples of the Sb compound include antimony trioxide, antimony acetate, antimony tartrate, potassium antimony tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, triphenyl antimony and the like. The Sb compound is added so that the residual amount of Sb in the produced polymer is in the range of 50 to 250 ppm.

As the Al compound, specifically,
Aluminum formate, aluminum acetate, basic aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, aluminum laurate, aluminum stearate, aluminum benzoate, aluminum trichloroacetate, aluminum lactate,
Carboxylates such as aluminum citrate and aluminum salicylate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, polyaluminum chloride,
Inorganic acid salts such as aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum phosphate, aluminum phosphonate, aluminum methoxide, aluminum ethoxide, aluminum n-propoxide, aluminum iso-propoxide, aluminum n-butoxide, aluminum t-butoxide, etc. Aluminum chelate compounds such as aluminum alkoxide, aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetate diiso-propoxide, trimethylaluminum, triethylaluminum and other organoaluminum compounds and their partial hydrolysates. , Aluminum oxide and the like. Among these, carboxylates, inorganic acid salts and chelate compounds are preferable, and among these, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride and aluminum acetylacetonate are particularly preferable. The Al compound is added so that the amount of Al remaining in the produced polymer is in the range of 5 to 200 ppm.

In the method for producing polyester of the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination. Examples of alkali metals and alkaline earth metals include Li, Na, K, Rb, Cs, Be and M.
At least one selected from g, Ca, Sr, and Ba is preferable, and the use of an alkali metal or a compound thereof is more preferable. When using an alkali metal or a compound thereof, use of Li, Na and K is particularly preferable.
Examples of the alkali metal or alkaline earth metal compound include, for example, formic acid, acetic acid, propionic acid, butyric acid of these metals,
Saturated aliphatic carboxylates such as oxalic acid, unsaturated aliphatic carboxylates such as acrylic acid and methacrylic acid, aromatic carboxylates such as benzoic acid, halogen-containing carboxylates such as trichloroacetic acid, lactic acid, citric acid, Hydroxycarboxylic acid salts such as salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, hydrogen phosphate, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid, bromic acid, etc. Acid salts, organic sulfonates such as 1-propanesulfonic acid, 1-pentanesulfonic acid and naphthalenesulfonic acid, organic sulfates such as laurylsulfate, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert. -Alkoxides such as butoxy, chelate compounds with acetylacetonate, hydrides,
Examples thereof include oxides and hydroxides.

The above-mentioned alkali metal compound or alkaline earth metal compound is added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution or the like. The alkali metal compound or the alkaline earth metal compound is added so that the residual amount of these elements in the produced polymer is in the range of 1 to 50 ppm.

Various P compounds can be used as stabilizers. Examples of the P compound used in the present invention include phosphoric acid, phosphorous acid and their derivatives. Specific examples include phosphoric acid, phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, Phosphoric acid, trimethyl phosphite, triethyl phosphite, tributyl phosphite, methylphosphonic acid,
Methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid diphenyl ester, and the like, which may be used alone or in combination of two or more. You may use together. The P compound is 1 to 1 as the residual amount of P in the produced polymer.
It can be added at any stage of the above-mentioned polyester formation reaction step so that it is in the range of 1000 ppm.

The molten polyester obtained from the final polycondensation reactor is then sent to the chip forming step (c). In the chipping step (c), the melt polycondensed polyester is extruded into the water through the pores of the die and cut in water, or is extruded into the air and immediately cut while cooling with cooling water. Chiped. The water adhering to the chip surface is removed by an air flow or the like, and is dried by hot air or the like as necessary. The cooling water discharged from the chip forming step (c) alone or together with the chips is sent to a cooling water storage tank or the like for reuse, and mixed with the introduced water introduced from outside the system in this tank, After adjusting the temperature to a certain temperature, it is used as cooling water for chips. Here, the melt polycondensation step (b) refers to the stage from the end of the low polymer production step (a) to the discharge from the final melt polycondensation reactor via a die.

The melt polycondensed polyester obtained as described above is extruded through the pores after completion of the melt polycondensation, and is made into chips while being cooled with cooling water. Since using distilled water as cooling water in the chip formation step (c) is disadvantageous in terms of cost, it is common to use industrial water (natural water) obtained by simply treating water from rivers, groundwater, drainage, etc. Target. Usually, this industrial water is collected from river water, groundwater, etc., and sterilized without changing the shape of water (liquid),
It is a product that has undergone processing such as foreign matter removal. In addition, natural water that is generally used for industrial purposes is derived from natural sources such as inorganic particles such as silicates, aluminosilicates and other clay minerals, bacteria, bacteria, and spoiled plants and animals. It contains a large amount of organic compounds having, or industrially used organic compounds.

However, when industrial water is used as cooling water for forming chips, the problem that the flavor and aroma of the contents of the molded container obtained from polyester are extremely deteriorated, and that when the obtained polyester is molded There was also a problem that the crystallization of the above became a bottle with poor transparency, and that the shrinkage of the plug part due to the crystallization of the plug part did not fall within the specifications and capping failure occurred. Further, the metal compound in the industrial water attached to the chip surface and brought into the solid-state polymerization reaction device in the chip forming step adheres to the vessel wall of the solid-state polymerization device together with a part of the surface layer of the polyester chip. It becomes a scale by heating at high temperature for a long time. Then, there is a problem that this is sometimes peeled off or fused to the surface of the chip and mixed in the polyester chip to become a foreign substance in the molded body such as a bottle, which lowers the commercial value.

In the method for producing polyester of the present invention, sodium content, magnesium content, silicon content and calcium content in the cooling water in the chipping step (c) are N, M, S, respectively. In the case of C, at least one, preferably all of the following (1) to (4) is chipped into the melt polycondensed polyester, and then the melt polycondensed polyester is solid-phase polymerized. This solves the above problems. N ≤ 1.0 (ppm) (1) M ≤ 0.5 (ppm) (2) S ≤ 2.0 (ppm) (3) C ≤ 1.0 (ppm) (4)

The sodium content (N) in the cooling water is preferably N≤0.5 ppm, more preferably N.
≦ 0.1 ppm.

The magnesium content (M) in the cooling water is
M ≦ 0.3 ppm is preferable, and M ≦ 0.1 ppm is more preferable.

The content (S) of silicon in the cooling water is
S ≦ 0.5 ppm is preferable, and S ≦ 0.3 ppm is more preferable. Furthermore, the calcium content (C) in the cooling water is preferably C ≦ 0.5 ppm, more preferably C ≦ 0.1 ppm.

The lower limits of the sodium content (N), magnesium content (M), silicon content (S) and calcium content (C) in the cooling water are N ≧
0.001ppm, M ≧ 0.001ppm, S ≧ 0.0
2 ppm and C ≧ 0.001 ppm. In order to make it below such a lower limit value, enormous capital investment is required, and the operating cost becomes very high, so that economical production is difficult.

Cooling water whose sodium content (N), magnesium content (M), silicon content (S) and calcium content (C) satisfy the above (1) to (4). The transparency of the molded product from the polyester obtained by solid-phase polymerizing the melt polycondensed polyester chipped while cooling with the use of is extremely excellent, and the filter clogging during spinning is small, and the operability is very stable. When using cooling water that deviates from the above conditions, these metal-containing compounds adhere to the polyester chip surface, the crystallization rate of the final polyester obtained is very fast, and its fluctuation becomes large, Moreover, only polyester containing foreign substances containing these metals can be obtained, which is not preferable.

A method for suppressing the sodium content, magnesium content, silicon content, and calcium content of the cooling water of the chips within the above ranges will be illustrated below, but the present invention is not limited thereto.

In order to reduce sodium, magnesium, calcium and silicon in the cooling water, a chip forming step (c)
An apparatus for removing sodium, magnesium, calcium, and silicon is installed at at least one place in the process until industrial water is sent to. A filter is installed to remove clay minerals such as particulate silicon dioxide and aluminosilicate. Examples of the device for removing sodium, magnesium, calcium, and silicon include an ion exchange device, an ultrafiltration device, and a reverse osmosis membrane device. Further, the particle size present in the introduced water introduced from outside the system is 1 to
It is desirable to use water in which particles of 25 μm are not more than 50,000 / 10 ml. Particle size of introduced water 1-25μ
The number of m particles is preferably 10,000 particles / 10 ml
The number is preferably 5000 pieces / 10 ml or less, more preferably 3000 pieces / 10 ml or less.

The lower limit value of the particles having a particle size of 1 to 25 μm is 1 particle / 10 ml or more, and in order to make it lower than this lower limit, enormous equipment investment is required, and the operating cost becomes very high. Economical production is difficult.

Particles having a particle size of more than 25 μm in the introduced water are
Although not particularly specified, preferably 2000 /
It is 10 ml or less, more preferably 500 pieces / 10 ml or less, further preferably 100 pieces / 10 ml, and particularly preferably 10 pieces / 10 ml or less.

The particles having a particle size of less than 1 μm in the introduced water are not particularly specified in the present invention, but in order to obtain a transparent molded product or a polyester which gives a molded product having an appropriate crystallization rate. The smaller the number, the better. Particle size 1
The number of particles less than μm is preferably 100,000 /
10 ml or less, more preferably 50,000 pieces / 10 ml
Or less, more preferably 20,000 pieces / 10 ml or less,
Particularly preferably, it is 10,000 pieces / 10 ml or less. 1
As a method for removing and controlling particles having a size of μm or less from water, a microfiltration method or an ultrafiltration method using a membrane such as a ceramic membrane or an organic membrane can be used.

Below, 50,000 / 10 particles having a particle size of 1 to 25 μm are introduced in the introduced water introduced in the chip forming step (c).
A method of controlling the amount to be less than or equal to ml is illustrated, but the present invention is not limited to this.

As a method for reducing the number of particles in water to 50,000 particles / 10 ml or less, an apparatus for removing particles is installed at at least one location until natural water such as industrial water is supplied to the chip forming step (c). . Preferably, a device for removing particles is installed between the natural water collecting port and the chipping step, and the particles having a particle size of 1 to 25 μm in the water supplied to the chipping step (c) are Content 500
It is preferable that the number is 100 pieces / 10 ml or less. As a device for removing particles, a filter filtration device, a membrane filtration device,
A precipitation tank, a centrifuge, a foam entrainment processing machine, etc. are mentioned.
For example, in the case of a filter filtration device, examples thereof include a belt filter system, a bag filter system, a cartridge filter system, a centrifugal filtration system and the like. Among them, a belt filter type, a centrifugal filtration type, and a bag filter type filtration device are suitable for continuous operation. Further, in the case of a belt filter type filtering device, examples of the filter material include paper, metal, cloth and the like. The size of the mesh of the filter is 5 to 100 μm, preferably 10 to 70 μm in order to efficiently remove particles and efficiently introduce water.
m, and more preferably 15 to 40 μm.

In the method for producing polyester of the present invention, the total oxygen consumption (TOD) of the introduced water introduced from the outside of the system to the chipping step (c) is 100 ppm or less, preferably 50 ppm or less, more preferably 10 ppm. By maintaining the ratio below, the above-mentioned flavor problem can be further solved. Total oxygen consumption of introduced water (TO
D) mainly represents the contents of carbon, hydrogen, nitrogen, sulfur, phosphorus, etc. that constitute the organic matter contained in the introduced water, and the total oxygen consumption of the introduced water introduced into the chip forming step (c) from outside the system. By setting the (TOD) to 100 ppm or less, the organic compound is adsorbed and permeates into the polyester chip and becomes one of the causes of the off taste and the offensive odor, and the flavor of the contents of the hollow molding container using such polyester chip and It can prevent the scent from becoming very bad.

When the total oxygen consumption (TOD) of introduced water introduced from outside the system is set to less than 0.1 ppm, it is necessary to carry out a treatment such as multistage distillation. In this case, the equipment cost becomes very high, and economical production becomes difficult.

A method for suppressing the total oxygen consumption (TOD) of the introduced water introduced into the chip forming step (c) to 0.1 to 100 ppm is illustrated below, but the present invention is not limited to this.

In order to suppress the total oxygen consumption (TOD) in the introduced water introduced into the chipping step (c) to the above-mentioned concentration, at least one or more steps before the chipping step (c) are supplied. In addition, an appropriate device for reducing organic substances and the like that cause total oxygen consumption (TOD) is installed. Preferably, from the water sampling port of the natural world, including the chipping step (c), piping for returning the water discharged from the chipping step to the cooling water storage tank again, and auxiliary equipment necessary for chipping such as a fine removing device. A device for removing the causative substance of the total oxygen consumption (TOD) is installed between the chip forming device and the total oxygen consumption (TOD) in the water introduced in the chip forming step (c) to 0. It is preferable to be 0.1 to 100 ppm.

Examples of the device for removing the substance causing the total oxygen consumption (TOD) include a degassing device, an ion exchange device, an activated carbon adsorption device and a reverse osmosis membrane device. It is preferable that the cooling water for the chips be used while being repeatedly recycled in order to improve the economical efficiency and the productivity.

The discharged cooling water is chipped again (c)
When it is returned to the cooling water and reused as cooling water, the content of ethylene glycol in the cooling water and the content of the monomer composed of terephthalic acid and ethylene glycol increase with time. If the amount of these compounds increases, the content of these in the chips will increase, and thus the flavor and aroma of the contents in the hollow molding container or the like using such polyester chips will become very poor.

Therefore, in the polyester production method of the present invention, water obtained by mixing at least a part of the water discharged from the chipping step (c) with freshly introduced water from outside the system is added to the chipping step (c). When used as the cooling water for the above), the ethylene glycol content, the monohydroxyethyl terephthalate content, and the bishydroxyethyl terephthalate content in the cooling water are each maintained at 100 ppm or less. The problem can be solved even further.

The method for adjusting the content of ethylene glycol or the like in the recycled water to be reused as cooling water to 100 ppm or less is illustrated below, but the present invention is not limited to this.

Further, by using the following method, not only ethylene glycol but also acetaldehyde in the recycled water,
Trace amounts of odorous components such as formaldehyde, acetic acid and formic acid can also be removed, and the content of these in the recycled water can be kept below a certain value.

In order to suppress an increase in the content of ethylene glycol or a monomer composed of terephthalic acid and ethylene glycol in the recycled water supplied to the chip forming step (c), the chip forming step (c) is used. A device for removing ethylene glycol and the like is installed at at least one place during the process of discharging the recycled water to the chip forming step (c) again.

As a method for removing ethylene glycol and the like, known methods such as a distillation treatment by a distillation apparatus, an activated carbon adsorption treatment, a bubbling treatment of an inert gas in water, a heat degassing treatment and the like can be mentioned. Another method is to add new ion-exchanged water to the reused water.

When the content of ethylene glycol or the like in the cooling water is less than 0.1 ppm, it is necessary to carry out a treatment such as multistage distillation. In this case, the equipment cost becomes very high, and economical production becomes difficult.

Further, in the method for producing polyester of the present invention, the water temperature of the cooling water in the chipping step (c) is 7
Surface area S (cm ² ) of the melt-polycondensed polyester cooled at a temperature of -50 ° C. and a cooling water amount V (cm ³ / sec).
/ Sec) ratio (V / S) preferably satisfies the following condition (5) for chip formation. 0.1 ≦ (V / S) ≦ 2.0 (5) Here, the surface area S of the melt-polycondensed polyester to be cooled
(Cm ² / sec) is the surface area of the polyester per unit time which is cooled by contact with cooling water before being cut into chips.

The water temperature of the cooling water is preferably 10 to 10.
The temperature is 40 ° C, more preferably 13 to 30 ° C.
In order to maintain the temperature of the cooling water below 7 ° C., very expensive equipment is required, and the energy cost becomes high, so it is not practical from the economical viewpoint. If the chipping equipment is of the type that cuts polyester strands,
If the temperature of the cooling water is lower than 7 ° C, the surface layer of the strand becomes too hard and the shape of the cut surface becomes poor, so that fines are often generated during cutting. In addition, when such chips are transported to the solid-state polymerization step, the impact and shearing forces acting on the cut surface in the transportation step and the solid-state polymerization step have a crystallization accelerating action and the transparency of the molded body becomes transparent as described later. This is not preferable because the generation of fines that affects the property is increased, and a structure having the same effect also occurs on the chip cutting surface. Further, also in the case of so-called underwater cutting equipment in which a melt polycondensed polyester melt is extruded into water from a die and cooled to be made into chips, the shape of the cut surface and the shape of the chips are similarly defective. On the other hand, when the temperature of the cooling water exceeds 50 ° C., the polyester is insufficiently cooled, resulting in defective chips or lumps in which 2 to several chips are fused, which is a problem.

On the other hand, when the ratio (V / S) of the amount of cooling water to the surface area of the melt polycondensed polyester is less than the above lower limit value, the melt polycondensed polyester is insufficiently cooled and the shape A defective chip or a lump of two to several chips fused together becomes a problem. In addition, the ratio (V
When / S) exceeds the above upper limit value, energy cost becomes high and it is not practical in terms of economy.

In the water discharged from the chipping step (c), polyester fine powder (hereinafter sometimes referred to as "fine") generated during chipping and finely-shaped abnormal products are mixed. However, during long-term production, the content of these in water increases, and the pipes and the chipping device become heavily soiled, resulting in clogging of the pipes. Further, in the case of continuous production, the fine content in cooling water increases with time, and this is sent to the solid-state polymerization step in a state of being attached to the chip surface, and as described later, works to promote crystallization of polyester,
It can be a problem. Therefore, it is possible to install a fine removal device such as a filter filtration device or a centrifuge at at least one place during the process until the water discharged from the chip forming step (c) returns to the cooling water storage tank or the like. .

The intrinsic viscosity of the polyester obtained from the final polycondensation reactor of the melt polycondensation is 0.30 to 0.80.
Deciliter / gram, preferably 0.35 to 0.75
Deciliter / gram, more preferably 0.40
It is preferably in the range of 0.70 deciliters / gram. If the intrinsic viscosity is less than 0.30, the degree of crystallinity becomes too high in the pre-crystallization before the solid phase polymerization, which slows down the solid phase polymerization rate, making economical production impossible. Also, due to the brittleness of the chips, a large amount of fine polyester is generated in the pre-crystallization and solid-state polymerization steps as will be described later, and the crystallization rate is very fast, and the rate fluctuation is very large. I can't. Further, when the intrinsic viscosity exceeds 0.80, the acetaldehyde content of the solid-phase polymerized polyester obtained from such melt polycondensed polyester cannot be reduced to 10 ppm or less. Therefore, the flavor and odor of the content of the molded product obtained from such solid-phase polymerized polyester are adversely affected. In addition, the hue also becomes very yellow, which reduces the commercial value of the obtained molded product.

The shape of the polyester chip may be any of cylinder type, square type, spherical type or flat plate type,
The average particle size is usually 1.5 to 5 mm, preferably 1.
6 to 4.5 mm, more preferably 1.8 to 4.0 mm
Is the range. For example, in the case of a cylinder type, it is practical that the length is 1.5 to 4 mm and the diameter is about 1.5 to 4 mm. In the case of spherical particles, the maximum particle size is 1.1 to 2.0 times the average particle size, and the minimum particle size is 0.
It is practical that it is 7 times or more. Further, it is practical that the weight of the chip is in the range of 10 to 30 mg / piece.

The polyester melt-polycondensed as described above, after being made into chips, is transported through a transport pipe to a storage silo or a solid phase polymerization step (d). When such chips are transported by, for example, a forced low-density transportation method using air, a large impact force is applied to the surface of the molten polycondensed polyester chips due to the collision with the pipe, and as a result, fine or film is produced. A large amount of particles are generated. Such a fine or film-like substance has an effect of promoting crystallization of polyester, and when it is present in a large amount, the transparency of the obtained molded product becomes very poor. Further, such fines and film-like substances include those having a melting point higher by about 10 to 20 ° C. than the normal melting point.
Further, when a melt polycondensed polyester chip is used with a feeder that is subjected to impact force or shear force, a very large amount of fines or film-like substances having a melting point higher than the normal melting point by about 10 to 20 ° C. or more are generated. . It is presumed that this is because the chip heats up due to a large force such as an impact force applied to the chip surface, and at the same time, oriented crystallization of polyester occurs on the chip surface, resulting in a dense crystal structure.

About 10 to 20 above the normal melting point
When melt-polycondensed polyester fine or film-like material having a melting point higher than ℃ is subjected to solid-state polymerization treatment together with melt-polycondensed polyester chips, and subsequently subjected to treatment such as contact treatment with water described below, these melting points are treated. It will be even higher than before. Even fine or film-like materials having a melting point not higher than the normal melting point by about 10 ° C. or higher, the melting point of the fine or film-like material is about 1% higher than the normal melting point.
It has a high melting point of 0 to 20 ° C or more. It is presumed that this is because the crystal structure is changed to a more dense crystal structure by these treatments.

Generally, the melt polycondensation polyester is about 10 to 2 above the normal melting point, depending on the production method.
It contains about 50 to several% by weight of fines having a high melting point of 0 ° C. or more, and fines including a part of film, and such fines are present in the melt polycondensed polyester chips in a uniform mixed state. Not ubiquitous but unevenly distributed. Therefore, when such a melt polycondensed polyester is subjected to solid phase polymerization, or when subsequently subjected to a contact treatment with water described later, the crystallization rate is further increased,
Further, only polyester having a very fluctuating speed can be obtained, which is a problem.

Therefore, in the method for producing polyester of the present invention, fine and / or film-like substances are removed in the intermediate step (e) between the chipping step (c) and the solid phase polymerization step (d). It is desirable to add the step (h) of removing fines.

Further, at least one of the fine content, the film-like material content, or the total content of the fine content and the film-like material content of the melt polycondensed polyester supplied to the solid phase polymerization step (d). One content is 500 ppm or less, preferably 300 ppm or less, more preferably 100 ppm or less, further preferably 50 p
It is preferably pm or less.

As a method of removing fines, a vibrating sieving process and an air flow classification process using an air flow which are separately installed in an intermediate process (e) between the chip forming process (c) and the solid phase polymerization process (d). , A method of treating in a gravity type classification step and the like. You may add these processes further. However, when the content of fines in the melt-polycondensed polyester is low, the object may be achieved without installing a device for removing these fines.

When the polyester according to the present invention is polyethylene terephthalate (hereinafter sometimes referred to as "PET"), the solid phase polymerization step (d) is carried out via the chip forming step (c). The fine and / or film-like substance contained in the melt-polycondensed polyester supplied has a melting peak temperature of 2 on the highest side of the melting peak temperature.
When the temperature exceeds 65 ° C, the solid-state PET obtained in the solid-state polymerization step (d) also has a fine peak or film-like substance whose melting peak temperature on the highest side of the melting peak temperature exceeds 265 ° C. For the above reasons, the crystallization rate of the molded product from the solid-phase-polymerized polyester obtained becomes too fast, and its fluctuation becomes very large, and the obtained preforming product for hollow molding is obtained. Whitening occurs, which makes normal stretching impossible, uneven thickness occurs, the transparency of the obtained hollow molded article deteriorates, and the fluctuation of transparency becomes large, which may cause a serious problem.

Further, as a method for preventing the inclusion of fine and / or film-like substances whose melting peak temperature on the highest temperature side of the melting peak temperature exceeds 265 ° C., for example, the following method is used. Can be mentioned. That is, after the melt polycondensation, the polyester melted from a die is extruded into water and cut in water, or extruded into the atmosphere and immediately cut with cooling water to be cut into chips, and then formed into chips. After draining the melted polycondensed polyester chips that have been removed, chips, fines, and film-like substances of shapes other than the prescribed size are removed by a vibration sieving process and an airflow classification process using an air flow. Send to storage tank. The chips are withdrawn from the tank by a screw feeder and to the next step by a plug transportation method or a bucket conveyor method, and immediately before the solid-state polymerization step (d) by air flow. A fine air removal process is performed by providing an air flow classification process or a vibration type sieving process.
Further, the molten polycondensed polyester from which the fine or film-like matter has been removed is again subjected to a fine or film-like process by an air stream classification process using an air flow immediately before the solid-state polymerization step (d), or a vibrating sieving step. It is also possible to remove the particulate matter and directly add it to the solid phase polymerization step (d).
When transporting melt-polycondensed polyester chips to a solid-state polymerization facility, or when transporting polyester chips after solid-state polymerization to a sieving process, a contact treatment process with water, or a storage tank, most of these transportations are carried out. Adopts a plug transportation method or a bucket type conveyor transportation method, and uses a screw feeder to extract chips from the crystallization device or solid-state polymerization reactor. Use a device that can minimize the impact on piping.

The melt polycondensed polyester thus obtained is subjected to solid phase polymerization by a conventionally known method in the solid phase polymerization step (d). First, the melt polycondensed polyester to be subjected to solid-phase polymerization is heated at a temperature of 100 to 210 ° C. for 1 to 5 hours under an inert gas or under reduced pressure, or an atmosphere of steam or an inert gas containing steam. Pre-crystallized. Then, solid phase polymerization is performed at a temperature of 190 to 230 ° C. for 1 to 30 hours in an inert gas atmosphere or under reduced pressure. In the case of polyester having an intrinsic viscosity of 1.0 or more used for direct blow, the solid phase polymerization time may exceed 30 hours. After solid phase polymerization, if necessary, under reduced pressure or in an inert gas atmosphere, about 1
It is cooled to 50 to 50 ° C or lower. Here, the solid phase polymerization step (d) means from after the chip forming step (c) to immediately before the post step (f) after the solid phase polymerization.

The solid-phase-polymerized polyester is used for the contact treatment step with water, which will be described later in the transportation pipe, the thermoplastic resin compounding step, the transportation of silos for storage, flexible containers, etc.
It is transported to a storage container or a molding process.
When such chips are transported by a forced low-density transportation method using air, for example, like the above-mentioned melt polycondensation polyester chips, the surface of the solid-phase-polymerized polyester chips is collided with a pipe by collision. A large impact force is applied, and as a result, a large amount of fines and film-like substances are generated as in the case of the melt polycondensed polyester. Such a fine or film-like substance has the effect of promoting crystallization of the polyester as in the case of the polyester after the melt polycondensation, and when it is present in a large amount, the transparency of the obtained molded product is improved. Becomes very bad. In addition, such fines and film-like materials have a melting point of about 1 from the normal melting point.
Those having a melting point higher than 0 to 20 ° C. are included. Also,
Even when solid-phase polymerization is performed using a rotary solid-state polymerization device, or when a feeding device that applies impact force or shear force to the solid-state polymerization polyester chip is used, the melting point is about 10 to 20 ° C or higher than the normal melting point. An extremely large amount of fine particles and films with a high melting point are generated. The reason for the high melting point is the above-mentioned.

About 10 to 20 ° C. from such a normal melting point
When the solid-phase polymerized polyester containing the fine or film-like material having a high melting point is molded under normal molding conditions, such a high melting point crystal is not completely melted during melt molding and remains as a crystal nucleus. As a result, the crystallization rate at the time of heating becomes very fast, and the crystallization of the plug part of the hollow molding container becomes excessive, so that the shrinkage amount of the plug part does not fall within the specified value range, and The problem of capping failure and leakage of contents occurs. In addition, the preform for hollow molding is whitened, which makes normal stretching impossible,
Since the thickness unevenness occurs and the crystallization speed is high, the transparency of the obtained hollow molded article is deteriorated, and the fluctuation of the transparency becomes large, which is a problem.

Therefore, in the method for producing a polyester of the present invention, an intermediate step (g) between the solid phase polymerization step (d) and the subsequent step (f) installed after the solid phase polymerization step (d) is performed. Before the post-process (f) as described above from the polyester subjected to the solid-phase polymerization treatment in the solid-phase polymerization process (d), by adding a fine removal process (h) for removing fines and / or film-like substances. In addition, it is desirable to separate and remove fines and / or film-like substances.

Further, the fine content of the solid-phase polymerized polyester supplied in the subsequent step (f), the content of the film-like material,
Alternatively, at least one of the total content of the fine content and the film-like material content is 500 p.
pm or less, preferably 300 ppm or less, more preferably 100 ppm or less, and further preferably 50 ppm or less.

As a method for removing fines, the solid phase polymerization step (d) and the subsequent step (f) which is installed after the solid phase polymerization step (d) are separately installed in an intermediate step (g). Examples of the method include a vibrating sieving process, an airflow classification process using an air flow, and a gravity classification process. You may add these processes further. Further, when transporting the melt polycondensed polyester to the solid phase polymerization step (d), an apparatus with less generation of fines or the like is used, or an efficient apparatus for removing fines or the like is used in the intermediate step (g) after the solid phase polymerization. When installed, it is also possible to prevent the above problems from occurring without removing fines and the like from the melt polycondensed polyester supplied to the solid-state polymerization apparatus.

Further, in the method for producing polyester of the present invention, the subsequent step (f) means at least one of a contact treatment step with water and a thermoplastic resin compounding step.

In the case where the polyester according to the present invention is PET, the fine peak and / or film-like substance contained in the solid-phase-polymerized polyester has a melting peak temperature on the highest temperature side of the melting peak temperature of 265 ° C. When it exceeds, the crystallization rate of the molded body from the solid-phase polymerized polyester obtained for the above reason becomes too fast, or its fluctuation becomes very large, the preform for hollow molding obtained Whitening occurs, which makes normal stretching impossible, uneven thickness occurs, the transparency of the obtained hollow molded article deteriorates, and the fluctuation of transparency becomes large, which may cause a serious problem.

Therefore, in the case of the polyester having ethylene terephthalate as the main repeating unit obtained by the present invention, the fine, melt peak contained in the solid-state polymerized polyester supplied in the subsequent step (f) is used. The melting peak temperature on the highest temperature side is preferably 265 ° C. or lower.

As a method for preventing the solid-phase polymerized polyester from containing fines whose melting peak temperature on the highest side of the melting peak temperature exceeds 265 ° C., the same method and equipment as those for the melt polycondensed polyester are used. Can be used.

In the present invention, as described below, the melting point of fine is measured by using a differential scanning calorimeter (DSC), and the melting peak temperature of DSC is called the melting point. The melting peak representing this melting point is composed of one or more melting peaks. In the present invention, when there is one melting peak, the peak temperature and the melting peak are determined. -If there are multiple melting peaks,
Among the peaks, the melting peak temperature on the highest temperature side is referred to as "the peak temperature on the highest temperature side of the fine melting peak temperature",
In Examples and the like, it is referred to as "fine melting point".

In the polyester production process of the present invention, which includes the step (a) of removing the low polymer and the step (g) of removing fines, etc., from the low polymer production step (a) to the chip forming step (c). Solid-state polymerization step (d) to post-step (f)
Can be operated separately, and the production process including the low polymer production process (a) to the post-process (f) can be continuously operated.

The polyester obtained by the production method of the present invention is a mold stain due to oligomers such as cyclic trimers adhering to the inner surface of the mold, the gas exhaust port of the mold, the exhaust pipe, etc. during molding. In order to further prevent the above, contact treatment with water can be carried out after the solid phase polymerization.

The effect of such contact treatment with water is that the polyester is treated at 290 ° C. in a nitrogen atmosphere by the following method.
Increase in cyclic trimer after melting for 60 minutes at
The amount of increase in cyclic trimer (ΔCT amount) is 0.50% by weight or less, preferably 0.30% by weight or less,
More preferably, it is 0.10% by weight or less. A method of contact-treating the above polyester chips with water, steam or a gas containing steam will be described below.

Examples of the hot water treatment method include a method of immersing in hot water and a method of applying water on the chips with a shower. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the water temperature is 20 to 180 ° C., preferably 40 to 150.
C., more preferably 50 to 120.degree.

The method of industrially performing water treatment will be illustrated below, but the method is not limited to this. The treatment method may be either a continuous method or a batch method, but the continuous method is preferable for industrial use.

When water treatment of polyester chips is carried out in a batch system, a silo type treatment tank can be used. That is, the polyester chips are received in silos in a batch system and treated with water. When the polyester chips are treated with water continuously, the polyester chips can be continuously or intermittently received from the upper portion of the tower-type treatment tank for water treatment.

Whether the water treatment method is continuous or batchwise, the number of particles having a particle size of 1 to 25 μm existing in the water introduced from outside the system is X,
The content of sodium is N, the content of magnesium is M,
When the content C of calcium is S and the content of silicon is S, it is preferable that at least one of the following (6) to (10) is satisfied and the water treatment is performed. In addition, it is preferable that the water introduced from outside the system satisfies all the upper limits of the formulas. 1 ≤ X ≤ 50,000 (pieces / 10 ml) (6) 0.001 ≤ N ≤ 1.0 (ppm) (7) 0.001 ≤ M ≤ 0.5 (ppm) (8) 0.001 ≤ C ≤ 1 0.0 (ppm) (9) 0.01 ≤ S ≤ 2.0 (ppm) (10)

By setting any of the number of particles in the water introduced into the water treatment tank and the content of sodium, magnesium, calcium or silicon within the above range, a metal such as oxide or hydroxide called a scale can be obtained. The contained substance floats or precipitates in the treated water, or even adheres to the walls of the processing tank or piping, which adheres to and permeates the polyester chips, promotes crystallization during molding, and makes bottles with poor transparency. Can be prevented.

The number of particles in water introduced into the water treatment tank is 500
At least one of the steps up to the supply of natural water such as industrial water to the treatment tank is carried out as a method of reducing the number to 100 pieces / 10 ml or less.
Install devices to remove particles at more than one place. Preferably from the natural water sampling port, to the treatment tank described above, a pipe for returning the water drained from the treatment tank to the treatment tank again, a fine removal device, and the like, to a treatment device including incidental equipment necessary for water treatment An apparatus for removing particles is installed between them, and the content of particles having a particle size of 1 to 25 μm in water supplied to the processing apparatus is set to 1 to 5
It is preferable that the number is 0000 pieces / 10 ml or less. As a device for removing particles, the same device as that used for removing particles in chip cooling water can be mentioned.

In order to reduce sodium, magnesium, calcium and silicon in the water introduced into the water treatment tank, at least one or more of sodium and magnesium are supplied in the process until natural water such as industrial water is supplied to the treatment tank.
Install a device to remove calcium and silicon. Examples of these devices include the same devices as those used for the treatment of chip cooling water.

Regardless of whether the water treatment method is continuous or batch, if all or most of the treated water discharged from the treatment tank is treated as industrial wastewater, a large amount of new water can be used. Not only that, but there is concern that the increase in the amount of wastewater will have an impact on the environment. That is, by returning at least a part of the treated water discharged from the treatment tank to the water treatment tank and reusing it, it is possible to reduce the necessary amount of water, and it is possible to reduce the effect on the environment due to the increase in the amount of drainage. If the wastewater returned to the water treatment tank maintains a certain temperature,
Since the heating amount of the treated water can be reduced, it is preferable that the treated water discharged from the treated layer be returned to the water treated layer and reused. Further, by reusing the water, the flow rate of the treated water in the treated layer can be increased, and as a result, the fines and film-like substances attached to the polyester chips can be washed off, so that an effect of removing the fines is also produced. Here, as the treated water which is discharged from the water treatment tank and then returned to the treatment tank and reused, the overflow of the water treatment tank is used.
There are water discharged from the mouth and treated water discharged from the treatment tank together with the polyester chips, and then separated from the chips.

When the treatment is carried out by contacting the polyester chips with steam or a steam-containing gas, 50 to 50
Steam or steam-containing gas or steam-containing air at a temperature of 150 ° C., preferably 50 to 110 ° C. is preferably supplied or present as steam in an amount of 0.5 g or more per 1 kg of granular polyethylene terephthalate. The granular polyethylene terephthalate is contacted with steam. The contact between the polyester chips and steam is usually 10 minutes to 2 days, preferably 20 minutes to 10 days.
Done on time.

The method for industrially carrying out the contact treatment between the granular polyethylene terephthalate and steam or a gas containing steam is shown below, but the method is not limited to this. Further, the treatment method may be either a continuous method or a batch method.

When the polyester chips are subjected to the contact treatment with steam in a batch system, a silo type treatment apparatus can be used. That is, the polyester chips are received in a silo, and steam or a steam-containing gas is supplied in a batch method to perform contact treatment.

When the polyester chips are continuously contacted with steam, granular tower terephthalate is continuously received from the upper part in a tower type processing apparatus, and steam is continuously supplied in cocurrent or countercurrent to contact with steam. Can be processed.

Also in the case of the contact treatment with water, steam or a gas containing steam, the fine content of the polyester chips before the treatment, the film-like content, or the total content of the fine content and the film-like content is It is desirable to reduce the content of either one to about 500 ppm or less.

As described above, when treated with water or steam, the granular polyethylene terephthalate is drained by a draining device such as a vibrating screener or a simon carter, and transferred to the next drying step if necessary. To do.

For drying the polyester chips which have been contact-treated with water or steam, a commonly used polyester drying process can be used. As a method for continuously drying, a hopper-type aeration dryer in which polyester chips are supplied from the upper part and a drying gas is aerated from the lower part is usually used. As a dryer for batch-type drying, drying may be carried out under atmospheric pressure while ventilating a drying gas. Although atmospheric air may be used as the dry gas, dry nitrogen and dehumidified air are preferable from the viewpoint of preventing a decrease in molecular weight due to hydrolysis or thermal oxidative decomposition of the polyester.

In the present invention, such a dried polyester is passed through a sieving step and a fine removing step by an air stream in the same manner as described above, so that the fine content of the polyester is about 5000 ppm or less, preferably 3000 ppm. It is desirable to reduce the amount to 1000 ppm or less, more preferably 1000 ppm or less, further preferably 500 ppm or less, and most preferably 100 ppm or less.

When the polyester obtained by the production method of the present invention is used for hollow molding, the mouth plug portion is subjected to heat crystallization treatment depending on the usage. In some cases, it is difficult to control crystallization due to fluctuations, and in such a case, a large amount of defective products occurs. In order to solve such problems, it is desirable to blend at least one resin selected from the group consisting of polyolefin resin, polyamide resin, and polyacetal resin with the polyester obtained by the production method of the present invention.

The blending ratio of the above-mentioned polyolefin resin and the like is 0.1 ppb to 50,000 ppm, preferably 0.1.
3 ppb-10000 ppm, more preferably 0.5 p
pb-100 ppm, more preferably 1.0 ppb-
It is 1 ppm, particularly preferably 1.0 ppb to 45 pbb. If the compounding amount is less than 0.1 ppb, the crystallization speed will be very slow and the mouthpiece of the hollow molded article will not be sufficiently crystallized. Therefore, if the cycle time is shortened, the amount of shrinkage of the mouthpiece will be regulated. Capping failure occurs because it does not fall within the value range, and the stretch heat-fixing mold for molding the heat-resistant hollow molded product is heavily contaminated, and the mold is frequently cleaned when trying to obtain a transparent hollow molded product. There must be. If it exceeds 50,000 ppm, the crystallization rate will be high and the crystallization of the plug part of the hollow molded article will be excessive, and the amount of shrinkage and shrinkage of the plug part will not fall within the specified range, resulting in poor capping. Leakage of the product occurs and the preform for the hollow molded body is whitened, which makes normal stretching impossible. In the case of a sheet-like material, 5000
If it exceeds 0 ppm, the transparency becomes extremely poor, and the stretchability becomes poor so that normal stretching is impossible and only a stretched film having large thickness unevenness and poor transparency can be obtained. Also,
When the above-mentioned polyolefin resin or the like is used alone, it has almost no effect on the prevention of stains on the heating die, but it has been found to be very effective on the stains on the die by coexistence with a specific amount of fines. In the method for producing a polyester of the present invention, the polyolefin resin blended with the polyester may be a polyethylene resin, a polypropylene resin, or an α-olefin resin. Further, these resins may be crystalline or amorphous.

In the method for producing polyester of the present invention, examples of the polyethylene resin to be blended with the polyester include homopolymers of ethylene, ethylene and propylene, butene-1,3-methylbutene-1, pentene-1, Other α having about 2 to 20 carbon atoms such as 4-methylpentene-1, hexene-1, octene-1, and decene-1
-Copolymers with olefins and vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, and styrene can be mentioned. Specifically, for example, low / medium / high density polyethylene (branched or linear) ethylene homopolymer, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-4-methyl, etc. Pentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene-vinyl acetate copolymer,
Examples thereof include ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-ethyl acrylate copolymers, and other ethylene-based resins.

In the method for producing a polyester of the present invention, examples of the polypropylene resin to be blended with the polyester include a homopolymer of propylene, propylene and ethylene, butene-1,3-methylbutene-1,
Pentene-1,4-methylpentene-1, hexene-
Other α-olefins having about 2 to 20 carbon atoms such as 1, octene-1, and decene-1, and vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, and styrene. And the like. Specific examples thereof include propylene-based resins such as propylene homopolymer, propylene-ethylene copolymer, and propylene-ethylene-butene-1 copolymer.

In the method for producing a polyester of the present invention, the α-olefin resin blended with the polyester is, for example, 4-methylpentene-1 homopolymers of α-olefins having about 2 to 8 carbon atoms, And other α-olefins having about 2 to 20 carbon atoms such as ethylene, propylene, butene-1, 3-methylbutene-1, pentene-1, hexene-1, octene-1, and decene-1. And the like. Specifically, for example, butene-1 homopolymer, 4-methylpentene-1
Homopolymer, butene-1-ethylene copolymer, butene-
Examples thereof include butene-1 type resins such as 1-propylene copolymers and copolymers of 4-methylpentene-1 and C _{2 to} C ₁₈ α-olefins.

Further, in the method for producing a polyester of the present invention, examples of the polyamide resin blended with the polyester include butyrolactam, δ-valerolactam,
Polymers of lactams such as ε-caprolactam, enantolactam and ω-laurolactam, 6-aminocaproic acid,
Polymers of aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, undecamethylenediamine,
Aliphatic diamines such as 2,2,4- or 2,4,4-trimethylhexamethylenediamine, 1,3- or 1,4-
Alicyclic diamines such as bis (aminomethyl) cyclohexane and bis (p-aminocyclohexylmethane), diamine units such as aromatic diamines such as m- or p-xylylenediamine, and glutaric acid, adipic acid, suberic acid, Polycondensates with aliphatic dicarboxylic acids such as sebacic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, dicarboxylic acid units such as aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and copolymers thereof Specifically, for example, nylon 4, nylon 6, nylon 7, nylon 7, nylon 8, nylon 9, nylon 11, nylon 12, nylon 66, nylon 69, nylon 610,
Nylon 611, Nylon 612, Nylon 6T, Nylon 6I, Nylon MXD6, Nylon 6 / MXD6,
Nylon MXD6 / MXDI, Nylon 6/66, Nylon 6/610, Nylon 6/12, Nylon 6/6
T, nylon 6I / 6T and the like. Further, these resins may be crystalline or amorphous.

In the method for producing a polyester of the present invention, examples of the polyacetal resin blended with the polyester include polyacetal homopolymers and copolymers. As the polyacetal homopolymer, A
The density measured by STM-D792 is 1.4.
Polyacetal having a melt flow ratio (MFR) of 0 to 1.42 g / cm ³ , measured by ASTM D-1238 at 190 ° C. and a load of 2160 g of 0.5 to 50 g / 10 minutes is preferable.

Further, as the polyacetal copolymer,
The density measured by the method of ASTM-D792 is 1.
38 to 1.43 g / cm ³ , a polyacetal copolymer having a melt flow ratio (MFR) measured at 190 ° C. and a load of 2160 g of 0.4 to 50 g / 10 min by the measuring method of ASTMD-1238 was obtained. preferable. Examples of these copolymerization components include ethylene oxide and cyclic ethers.

Further, as a method of blending the thermoplastic resin such as the above-mentioned polyolefin resin with the polyester, a method of directly adding the thermoplastic resin to the polyester so that the content thereof is within the above range and melt-kneading Or, by a conventional method such as a method of adding as a master-batch and melt-kneading, or the like, the thermoplastic resin is used in the production step of the polyester, for example, during melt polycondensation, immediately after melt polycondensation, immediately after pre-crystallization. , During solid phase polymerization, immediately after solid phase polymerization, etc., or during the period from the end of the manufacturing stage to the molding stage, etc., as a powder or granules, or polyester chips It is also possible to use a method in which the above-mentioned thermoplastic resin member is mixed under such a flow condition as described above and then mixed and then melt-kneaded.

Here, as a method of contacting the polyester chip-shaped body with the above-mentioned thermoplastic resin member under a flow condition, the polyester chip-like member is prepared in the empty space where the thermoplastic resin member exists. It is preferable to bring the members into collisional contact, and specifically, for example, during a manufacturing process such as immediately after melt polycondensation of polyester, immediately after pre-crystallization, immediately after solid-phase polymerization, or during a transportation step as a product of polyester chips. A part of the aerodynamic transport pipe, gravity transport pipe, silo, magnet part of the magnet catcher, etc. when filling and discharging the transport container of Or lining with the above-mentioned thermoplastic resin, or the above-mentioned thermoplastic resin part such as a rod-shaped or net-like body in the transfer path. The by, for example installation, and a method of transferring the polyester chips. The contact time of the polyester chip with the member is usually an extremely short time of about 0.01 second to several minutes, but a small amount of the thermoplastic resin can be mixed into the polyester.

Further, in the present invention, in order to produce a polyester having an appropriate crystallization rate and giving a small variation in the crystallization rate, before the polyester is contact-treated with a member made of the above-mentioned thermoplastic resin. In addition, by treating the polyester in a sieving process for removing fines and film-like substances and a removal process such as fines by an air stream, the fine content of polyester, the film-like substance content, or the fine content and film-like substance content. It is desirable to reduce the content of any one of the total content to 500 ppm or less.

On the other hand, when the member made of the thermoplastic resin and the polyester are contact-treated, it is preferable that the thermoplastic resin is present in a state of being attached to the surface of the polyester chip. The thermoplastic resin member may be a polyester chip depending on the magnitude of the impact force when it collides with the member, the pressure force when contacting the member, or the impact resistance and peeling resistance of the thermoplastic resin member. There is also a state in which it is mixed with the above-mentioned contact-treated polyester chip in a state where it does not adhere to, that is, in a state independent of the polyester chip. The molded product obtained from the polyester in such a mixed state has a too high crystallization rate, or has a very large fluctuation in the rate.
In the case of a preformed body for a hollow molded body, only a hollow molded body having a large transparency and whitening and transparency unevenness, normal stretching is impossible, and large thickness unevenness and poor transparency can be obtained. Usually, the above contact-treated polyester is present as fine fine particles, but sometimes in the form of granules or agglomerates having an average particle diameter of about 0.5 to several mm, independent of the polyester chips. It may be mixed in. In such a case, the thermoplastic resin becomes a foreign substance in the obtained molded body, and as a result, the resulting molded body has unevenness in thickness, pores,
There are many defects such as whitening. Therefore, it is desirable to remove the fine particles, particles or lumps of the thermoplastic resin existing independently of the polyester chips before molding.

The method for separating and removing the fine particles, particles or lumps of the thermoplastic resin from the polyester which has been contact-treated with the member made of the thermoplastic resin includes the following methods. That is, after melt-polycondensed polyester or solid-phase polymerized polyester is contact-treated with a member made of the above-mentioned thermoplastic resin, it is treated by a vibration sieving step and a stream classification step by an air flow, or a washing step with ion-exchanged water. The thermoplastic resin in the form of fine granules, granules and lumps is removed by a method such as the method described above, or a method of performing a floating selection treatment. The method of separating and removing the fine particles, particles or lumps of the thermoplastic resin as described above is also effective as a method of removing the polyester fines or film-like materials described below.

In the polyester production process, the melt polycondensation process (b) to the solid phase polymerization process (d), or the solid phase polymerization process (d) to the sieving process, airflow classification process and the like are performed. It is filled in containers such as silos, hoppers of molding machines, and containers for transportation.For the transportation and drying of polyester between these processes, air is blown into these processes and the vicinity of the equipment. Used by putting. Conventionally, such air is either left untreated or used according to JIS B 9908 (199).
It was generally used only after being treated by a cleaner equipped with a low-performance filter unit such as type 3 defined in 1). However, when the air treated in such a process is used, there is a problem that only a molded product having poor transparency can be obtained.

Therefore, in the method for producing a polyester of the present invention, the melt polycondensation step (b), the chip forming step (c), the solid phase polymerization step (d), the post step (f), and the fine removal step (h). As a gas that comes into contact with the polyester in at least one step of
Out of the system in which the number of particles of m is 1,000,000 particles / cubic feet or less, preferably 100,000 particles / cubic feet or less, more preferably 10,000 particles / cubic feet or less, most preferably 1000 particles / cubic feet or less. It is desirable to use more introduced gas.

Particles having a particle diameter of less than 0.3 μm in a gas are not particularly specified, but in order to obtain a resin which gives a transparent molded product, it is preferable that the amount is small.
The number of particles having a particle size of less than 0.3 μm is preferably 100.
00000 pieces / cubic foot or less, more preferably 50
00000 pieces / cubic foot or less, more preferably 2
It is less than or equal to 000000 pieces / cubic foot.

The method of controlling the number of particles having a particle size of 0.3 to 5 μm in the gas introduced from the outside of the system to 1,000,000 particles / cubic foot or less is illustrated below, but the present invention is not limited to this. is not.

Particle size in gas introduced from outside the system 0.3 to 5
As a method of reducing the number of particles of μm to 1,000,000 / cubic feet or less, a cleaning device for removing the particles at least at one or more places during the process until the gas introduced from the outside comes into contact with the polyester chips Set up. In the case where the gas is air in the vicinity of these processes or equipment, the JIS introduced in the process until the air introduced by the blower from the air inlet comes into contact with the polyester chips.
A gas purifier equipped with a type 1 or / and type 2 filter unit defined in B 9908 (1991) is installed, and the number of particles having a particle size of 0.3 to 5 μm in the air is 1,000,000 / cubic fission. -It is preferable that In addition, JIS B 990 is installed in the air intake port described above.
It is possible to extend the life of the filter unit by installing the gas cleaning device equipped with the filter unit of the type 3 defined in 8 (1991) and using it together with the gas cleaning device equipped with the filter unit. Is.

JIS B 99 for removing particles in gas
As a material of the ultra-high performance filter (hereinafter referred to as HEPA filter) unit of type 1 defined in 08 (1991), a filter paper made of glass fiber can be mentioned.

Also, JIS B 9908 (1991)
Examples of the material for the high-performance filter unit of the type 2 defined in 1. include a filter made of polypropylene fiber, a filter made of a laminated body of polytetrafluoroethylene film and PET fiber cloth, and the like. Generally, an electrostatic filter made of polypropylene fiber is used. Also, JIS
Examples of the material of the low-performance filter unit of type 3 defined in B 9908 (1991) include non-woven fabric made of PET or polypropylene.

The lower limit of the number of particles having a particle size of 0.3 to 5 μm is 10 particles / cubic foot. To make the number below this lower limit, enormous equipment investment is required and the operating cost is also high. It is very expensive and difficult to produce economically.

According to the method for producing a polyester of the present invention, the intrinsic viscosity is 0.60 to 2.00 deciliter / gram, the acetaldehyde content is 10 ppm or less, and the cyclic 3
A spherulite formed when the content of the monomer is 0.5% by weight or less, the haze of the molded plate obtained by injection molding is 15% or less, and the molded plate obtained by injection molding is crystallized at elevated temperature. Number is 1 ×
It is possible to obtain a polyester having ethylene terephthalate as a main repeating unit in the range of 10 ⁹ to 15 × 10 ⁹ units / m ² .

The intrinsic viscosity of the polyester obtained by the production method of the present invention is 0.60 to 2.00 deciliter /
Grams, preferably 0.65 to 1.80 deciliters /
Gram, more preferably 0.70 to 1.50 deciliters / gram. When the intrinsic viscosity is less than 0.60 deciliter / gram, the mechanical properties of the obtained molded product are poor. On the other hand, if it exceeds 2.00 deciliters / gram, the resin temperature becomes high when melted by a molding machine or the like, and thermal decomposition becomes severe, and free low-molecular-weight compounds that affect aroma retention are increased, or a molded product is obtained. Will be colored yellow.

The content of diethylene glycol copolymerized in the polyester obtained by the production method of the present invention is 0.5 to 5.0 mol% of the glycol component constituting the polyester, preferably 1 It is from 0.0 to 4.5 mol%, more preferably from 1.5 to 4.0 mol%. In order to produce a polyester in which the content of diethylene glycol does not exceed 0.5 mol%, a large amount of a basic compound must be added, in which case the thermal stability of the polyester will be poor, and the polyester will not be colored. May become awful. Further, when the content of diethylene glycol exceeds 5.0 mol%, the content of acetaldehyde increases to 10 ppm or more, which causes a problem in flavor property.

The acetaldehyde content of the polyester obtained by the production method of the present invention is 10 ppm or less, preferably 8 ppm or less, more preferably 5 ppm.
The following is desirable. If it exceeds 10 ppm, the flavor property becomes a problem. Further, if it is 1 ppm or less, solid phase polymerization takes a long time, and it is not practical from the viewpoint of economy.

The content of the cyclic trimer of polyester obtained by the production method of the present invention is 0.50% by weight or less, preferably 0.45% by weight or less, more preferably 0.40% by weight or less. Is desirable. When the content of the cyclic trimer exceeds 0.50% by weight, oligomers such as the later-described cyclic trimer may form on the inner surface of the mold, the gas exhaust port of the mold, the exhaust pipe, etc. during molding. Staining of the mold due to the adhesion is a serious problem. Further, in order to reduce the content of the cyclic trimer to 0.20% by weight or less, solid phase polymerization takes a long time, which is not practical in terms of economy.

The polyester obtained by the production method of the present invention has a haze of 15% or less, preferably 13% or less, and more preferably a haze of a molded product having a thickness of 5 mm obtained by melt-molding the above polyester. It is 10% or less. When the haze is more than 15%, the transparency of the obtained molded product is deteriorated, which is a problem particularly in the case of stretched molded products.

Furthermore, the polyester obtained by the production method of the present invention is melt-injection-molded to have a thickness of 3 mm.
The number of spherulites generated when the test piece from the molded body of No. 1 is crystallized at elevated temperature is in the range of 1 × 10 ⁹ to 15 × 10 ⁹ pieces / m ² , preferably 2 × 10 ^{9 to} 12 × 10 ^9. range of pieces / m ^2, and more preferably 3 × 10 ⁹ ~10 × 10 ⁹ pieces / m ²
It is preferably in the range of.

There are many problems such as a high equipment cost and a very poor productivity in producing a polyester in which the number of spherulites does not reach 1 × 10 ⁹ pieces / m ² . The spherulite number is 15
When it exceeds × 10 ⁹ pieces / m ² , the transparency of the heat-resistant hollow molded article decreases, and the transparency becomes a problem especially in a large hollow molded article of 1.5 liters or more.

Here, the number of spherulites at the time of temperature crystallization of the molded body for specifying the polyester of the present invention is the thermomechanical analysis (TMA), type TM manufactured by Mac Science Co., Ltd.
The molded plate was heat-treated using A4000S and measured by the method described below.

The fine content of the solid-phase-polymerized polyester obtained by the method for producing a polyester of the present invention is 5
000 ppm or less, preferably 3000 ppm or less, more preferably 1000 ppm or less, further preferably 5
It is desirable to reduce it to 00 ppm or less, most preferably 100 ppm or less. When the application is a hollow molded article, the fine content is preferably 500 ppm or less.

Preferred examples of the polyester according to the present invention include ethylene terephthalate units of 99.5-9.
It is a polyethylene terephthalate (PET) containing 5.0 mol% and having a copolymerized diethylene glycol content of 0.5 to 5.0 mol%. As another example of polystel, ethylene terephthalate unit is 99.0-8.
5.0 mol%, the content of copolymerized diethylene glycol in the glycol component was 0.5 to 5.0 mol, and the content of copolymerized isophthalic acid in the dicarboxylic acid component was 0. 5 to 10 mol% of polyethylene terephthalate-isophthalate copolymer, 99.0 to 85.0 mol% of ethylene terephthalate units, and the content of copolymerized diethylene glycol in the glycol component is 0.5 to
5.0 mol, and the content of copolymerized ethylene-2,6-naphthalate units in the dicarboxylic acid component was 0.5.
10 mol% polyethylene terephthalate-naphthalate copolymer, ethylene terephthalate unit 99.0
To 85.0 mol%, the content of copolymerized diethylene glycol in the glycol component is 0.5 to 5.0 mol, and the copolymerized cyclohexane dimethanol in the glycol component is contained. A polyethylene terephthalate-cyclohexylene terephthalate copolymer having a content of 0.5 to 10 mol% and an ethylene terephthalate unit of 99.0 to 8
5.0 mol%, the content of copolymerized diethylene glycol in the glycol component is 0.5 to 5.0 mol, and the copolymerized neopentyl glycol is contained in the glycol component. An example is a polyethylene terephthalate copolymer having an amount of 0.5 to 10 mol%.

The polyester obtained by the production method of the present invention is a PET obtained by using a raw material such as dimethyl terephthalate or terephthalic acid recovered by purifying a used PET bottle by a chemical recycling method as at least a part of the starting raw material, Flake PE that is used PET bottle purified by mechanical recycling method and collected
It can be used as a mixture with T or PET in the form of chips.

It is also possible to simultaneously use a saturated fatty acid monoamide, an unsaturated fatty acid monoamide, a saturated fatty acid bisamide, an unsaturated fatty acid bisamide and the like in the polyester obtained by the production method of the present invention. Examples of the saturated fatty acid monoamide include lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide. Examples of unsaturated fatty acid monoamides include oleic acid amide, erucic acid amide ricino-acid amide, and the like. Examples of the saturated fatty acid bisamide include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, and hexamethylenebisbehenic acid. Examples include amides. Examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide and hexamethylenebisoleic acid amide. Preferable amide compounds are saturated fatty acid bisamide, unsaturated fatty acid bisamide and the like. The compounding amount of such an amide compound is in the range of 10 ppb to 1 × 10 ⁵ ppm.

Further, the polyester obtained by the production method of the present invention comprises a metal salt compound of an aliphatic monocarboxylic acid having 8 to 33 carbon atoms, such as naphthenic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearin. Acids, behenic acid, montanic acid, melissic acid, oleic acid, lithium salts of saturated and unsaturated fatty acids such as linoleic acid, sodium salts, potassium salts, magnesium salts,
It is also possible to use a calcium salt, a cobalt salt, etc. together. The compounding amount of these compounds is 10 ppb
Is in the range of up to 300 ppm.

The polyester obtained by the production method of the present invention can be preferably used as a hollow molding, a packaging material such as a tray or a biaxially stretched film, a film for coating a metal can, and the like. Further, the polyester obtained by the production method of the present invention can be used as a constituent layer of a multilayer molded body, a multilayer film or the like.

The polyester obtained by the production method of the present invention can be used for forming films, sheets, containers, and other packaging materials by using a commonly used melt molding method. Further, it is possible to improve the mechanical strength by stretching such a polyester in at least a uniaxial direction. Below, as a typical example, PET
Will be described.

PET obtained by the production method of the present invention
The stretched film consisting of a sheet-like material obtained by injection molding or extrusion molding is prepared by using any stretching method of uniaxial stretching, sequential biaxial stretching and simultaneous biaxial stretching which are usually used for stretching PET. Molded. It is also possible to form into a recup shape or a tray shape by pressure forming or vacuum forming.
In producing a stretched film, the stretching temperature is usually 80 to 130 ° C. The stretching may be uniaxial or biaxial, but biaxial stretching is preferable from the viewpoint of practical physical properties of the film. If the stretching ratio is uniaxial, it is usually 1.1 to 10.
Double, preferably 1.5 to 8 times, and if biaxially stretched, it is usually 1.1 to 8 in both the machine direction and the transverse direction.
Double, preferably 1.5 to 5 times. The longitudinal magnification / lateral magnification is usually 0.5 to 2, preferably 0.7 to 1.3. The obtained stretched film is
Further, heat fixing can be performed to improve heat resistance and mechanical strength. The heat setting is usually carried out under tension at 120 to 240 ° C., preferably 150 to 230 ° C. for usually several seconds to several hours, preferably several tens of seconds to several minutes.

In producing a hollow molded article, a briform formed from PET obtained by the production method of the present invention is stretch blow-molded.
The apparatus used in the blow molding can be used. Specifically, for example, a preform is once molded by injection molding or extrusion molding, and as it is or after processing the plug portion and the bottom portion, it is reheated, and biaxial stretch blow molding such as hot parison method or cold parison method. The law applies. The molding temperature in this case, specifically, the temperature of each part of the cylinder and nozzle of the molding machine is usually 260 to 290 ° C.
Is the range. The stretching temperature is usually 70 to 120 ° C., preferably 90 to 110 ° C., and the stretching ratio is usually 1.5 in the machine direction.
˜3.5 times, and 2 to 5 times in the circumferential direction.
The obtained hollow molded article can be used as it is, but in the case of beverages such as fruit juice and oolong tea which require heat filling, generally, heat-setting treatment is further performed in a blow mold to obtain heat resistance. It is used by imparting sex. The heat setting is usually carried out under tension such as compressed air at 100 to 200 ° C., preferably 120 to 180 ° C. for several seconds to several hours, preferably several seconds to several minutes.

In order to impart heat resistance to the spout,
The plug part of the preform obtained by injection molding or extrusion molding is crystallized in an oven equipped with a far infrared or near infrared heater, or the plug part is molded with the above heater after bottle molding. Crystallize.

The polyester obtained by the production method of the present invention may optionally contain other additives such as known ultraviolet absorbers, antioxidants, oxygen absorbers, oxygen scavengers,
A lubricant added from the outside or a lubricant that is internally precipitated during the reaction,
You may mix | blend various additives, such as a mold release agent, a nucleating agent, a stabilizer, an antistatic agent, and a dye and a pigment.

When the polyester obtained by the production method of the present invention is used in a film, the polyester composition contains calcium carbonate in order to improve handling properties such as slipperiness, winding property and blocking resistance. Inorganic particles such as magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, and magnesium phosphate; organic salt particles such as terephthalate salts such as calcium and calcium oxalate, barium, zinc, manganese, and magnesium; Inert particles such as crosslinked polymer particles such as homopolymers or copolymers of vinyl monomers of divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid or methacrylic acid can be contained. In addition, the measuring method of the main characteristic value in this invention is demonstrated below.

[0160]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples.
In addition, the measuring method of the main characteristic value in this invention is demonstrated below. (1) Intrinsic viscosity (IV) of polyester It was determined from the solution viscosity at 30 ° C. in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent.

(2) Diethylene glycol content (hereinafter referred to as [DEG content]) Decomposition with methanol, the DEG content was quantified by gas chromatography, and the ratio (mol%) to all glycol components was calculated. expressed.

(3) Acetaldehyde content (hereinafter referred to as "A
"A content") Sample / distilled water = 1 g / 2 ml is put in a glass ampoule that has been purged with nitrogen, the upper part is sealed and extracted at 160 ° C for 2 hours, and after cooling, acetaldehyde in the extract is a highly sensitive gas. It was measured by chromatography and the concentration was expressed in ppm.

(4) Content of cyclic trimer of polyester (CT content) A sample is dissolved in a hexafluoroisopropanol / chloroform mixture solution, and chloroform is further added to dilute it. Methanol is added to this to precipitate the polymer, which is then filtered. The filtrate was evaporated to dryness, the volume was made constant with dimethylformamide, and the cyclic trimer composed of ethylene terephthalate units was quantified by liquid chromatography.

(5) Measurement of fine content and film-like material content About 0.5 kg of resin was used as a sieve (A) with a wire mesh having a nominal size of 5.6 mm according to JIS-Z8801 and a nominal size of 1.7.
A sieve (diameter 20 cm) (B) having a metal mesh of mm was placed on the sieve in which the two stages were combined, and sieved with a rocking type sieving tow machine SNF-7 manufactured by Terraoka at 1800 rpm for 1 minute. This operation was repeated, and a total of 20 kg of the resin was sieved. If, in addition to the film-like material, two or more chips fused to each other or a chip-like material cut into a size larger than the normal shape are captured on the sieve (A), The remaining film-like material from which the syrup was removed and the fines sieved off under the sieve (B) were separately washed with ion-exchanged water, filtered with a G1 glass filter manufactured by Iwaki Glass Co., Ltd., and collected. These are put together with the glass filter in a dryer at 100 ° C.
After drying for 2 hours, it was cooled and weighed. The same operation of washing with ion-exchanged water and drying was repeated again to confirm that the weight became constant, and the weight of the glass filter was subtracted from this weight to obtain the fine weight and the weight of the film-like material.
Fine content or film content is fine weight or film weight / total screened resin weight. The total content is calculated from these values.

(6) Measurement of fine peak temperature of fine powder Differential scanning calorimeter (DS) manufactured by Seiko Denshi Kogyo KK
C), measured using RDC-220. In (5),
Fines collected from 20 kg of polyester were dried under reduced pressure at 25 ° C for 3 days, and a sample of 4 m was used for each measurement.
DSC measurement at a temperature rising rate of 20 ° C./min using g,
The melting peak temperature on the highest side of the melting peak temperature is determined. The measurement is performed on a maximum of 10 samples, and the average value of the melting peak temperatures on the highest temperature side is obtained.

(7) Number of spherulites at the time of temperature-induced crystallization of the molded body A test piece having a size of 8 mm × 10 mm was cut out from a plate portion having a thickness of 3 mm from the stepped molded plate of the following (10) to obtain a measurement sample. . The molded plate has a molecular orientation derived from the flow at the time of molding, but the orientation state varies depending on the site of the molded plate. Therefore, by sandwiching the molding plate between two polarizing plates whose polarization planes are orthogonal to each other, and observing the intensity distribution of the light passing through the molding plate when irradiating visible light from the direction perpendicular to the polarizing plate surface, the alignment is performed. I confirmed the condition. A test piece was cut out from a site that did not include nonuniform molecular orientation (orientation degree, orientation fluctuation, etc.) within the above dimensions.
At that time, the direction of the optical anisotropy is confirmed in advance, and the relationship with the direction of the test piece to be cut out is as follows. The orientation of the optical anisotropy was determined by a method described in New Polymer Experiment 6 Polymer Structure (2) (Kyoritsu Shuppan Co., Ltd.) using a polarizing microscope and a sensitive color inspection plate. The test piece was cut out so that the direction of the axis of small refractive index (axis of high light velocity) and the long axis of the test piece were parallel to each other. The disordered orientation and the unevenness of the cut surface introduced when cutting out the test piece significantly affect the measurement result. Therefore, the unevenness of the cut surface and the part in which the orientation was disturbed were removed by using a cutter to obtain a flat surface. In addition, the density of the test piece and the degree of molecular orientation also affect the results. The density and birefringence values are 1.3345 to 1.3355 g / cm ³ , respectively.
And 1.30 × 10 ^{−4 to} 1.50 × 10 ⁻⁴ .

The density was measured using a water-based density gradient tube using a resin sampled from the vicinity of the test piece collection site as a sample. Birefringence is determined by a polarizing microscope (ECLIPSE manufactured by Nikon
E600 POL) was used to measure by the Bereck compensator method. As the measured value, the value obtained at the center of the test piece was adopted. The test piece prepared as described above was used for thermomechanical analysis (TMA), type TM manufactured by Mac Science Co., Ltd.
Heat treatment was performed at A 4000S. 27g / mi from room temperature to 210 ℃ under a constant compressive load of 0.2g and Ar atmosphere
The temperature is raised at a rate of n., the temperature is kept at 210 ° C. for 180 seconds, then the temperature is lowered to a room temperature at a rate of 47 ° C./min., and the number of spherulites is measured by the following method. Using a Leica microtome RM2065, a 2 μm-thick section is prepared from the end of the test piece. This section is observed using a Nikon polarization microscope ECLIPSE E600POL. For observation, halogen lamp light was used as a light source, and monochromaticization was not performed by an interference filter or the like. The optical system is adjusted to a so-called crossed nicols state in which the optical axes of the polarizer and the analyzer are orthogonal to each other, and a sensitive color inspection plate of 530 nm is inserted in the optical path. The image is observed with a color CCD camera (HITACHI HV-C205) connected to a polarization microscope and stored as a still image in a Macintosh computer via an image capture board.

When observing the section with the above optical system,
Many spherulites are observed. When a 530 nm sensitive color inspection plate is inserted into the optical path for observation, the spherulites show symmetry reflecting the orientation of the optical anisotropy inside them. Specifically, spherulites are observed as if they were divided into four with their centers being symmetrical. Then, different colors are exhibited in the parallel direction and the vertical direction with respect to the axis having a low refractive index of the sensitive color inspection plate (parallel to the insertion direction). This color is an interference color when the retardation generated by the inspection plate increases with the sample and an interference color corresponding to the case where it decreases, and the azimuth of the optical axis of the inserted inspection plate and the optical inside the spherulites. Determined by the relationship of anisotropic orientation.

105 μm × 79 on the sample using a CCD camera
Take a picture of the μm area and save it in a computer recording device (such as a hard disk or magneto-optical disk).
From this image, the number of spherulites is measured using the image processing software Ultimage / Pro (Image and Measurement Co., Ltd.) on a Macintosh computer according to the following procedure. As described above, spherulites have two kinds of colors. Threshold level is set so that only one of the colors remains, and binarization is performed. By this operation, only the portion having one color is the measurement target. In addition, Primary Morp
Erosion in the hology menu is Number of integrations = 1
Run with. By this operation, the portions which are originally belonging to different spherulites but are connected are separated. After executing this operation, execute the Particle menu and read the value of Detected particles. At this time,
Particles with an area of 4 pixels or less are not measured. Since two particles are measured per spherulite, the value obtained by dividing the value of Detected particles read earlier by 2 is taken as the number of spherulites.

(8) Haze (% haze) and haze unevenness Samples were cut from the body of the following (10) (wall thickness: 5 mm) and the hollow molded body of (11) (wall thickness: about 0.45 mm). Measured with a haze meter manufactured by Nippon Denshoku Co., Ltd. Also,
The haze of the hollow molded article which was continuously molded 10 times was measured,
The haze spots were obtained by the following. Haze spot = maximum haze value / minimum haze value

(9) Foreign matter of hollow molded body Three hollow molded bodies of the following (11) were visually observed to obtain an average value, and evaluated as follows. ◎: There is no foreign matter ○: Very small amount of foreign matter (3 or less foreign matter having a size of 0.5 mm or less per hollow molded body) △: 0.5 mm or more per hollow molded body 5 to 10 foreign matter x: Very large number (more than 10 foreign matter having a size of 0.5 mm or more per hollow molding)

(10) Molding of Stepped Molded Plate A dried polyester was manufactured by Meiki Seisakusho M-150C (D
M) Molded by an injection molding machine at a cylinder temperature of 290 ° C. using a stepped flat plate mold cooled to 10 ° C. The obtained stepped molded plate was 2, 3, 4, 5, 6, 7, 8,
It is equipped with 9,3,11 mm thick plates of about 3 cm x about 5 cm square in a stepwise manner, and the weight of one piece is about 146.
It is g. A plate with a thickness of 3 mm is used for measuring the number of spherulites at the time of heating, and a plate with a thickness of 5 mm is used for measuring haze (% haze).

(11) Molding of Hollow Molded Body The polyester was dried by a dryer using nitrogen, and the resin temperature was 2 by an M-150C (DM) injection molding machine manufactured by Meiki Seisakusho.
The preform was molded at 95 ° C. The plug part of this preform is heated and crystallized by a homemade plug part crystallization device, and then biaxially stretch blow molded using a LB-01 stretch blow molding machine manufactured by Co-Poplast Co., Ltd., and subsequently at about 145 ° C. It was heat-fixed in the mold set as above to obtain a 2000 cc hollow molded body.

(12) Density increase due to heating of preform mouthpiece The preform mouthpiece was heat treated for 60 seconds with a home-made infrared heater, and a sample was taken from the top surface to measure the density.

(13) Average density of polyester chips,
Preform mouth plug density Measured at 30 ° C with a density gradient tube of a calcium nitrate / water mixed solution. The plug density was determined as an average value of 10 samples crystallized by the method (12).

(14) Thickness variation of hollow molded article Samples (3 cm x 3 cm) at four locations were randomly cut from the center of the body of the hollow molded article of (11) above, and the thickness was measured with a digital thickness meter (same). The inside of the sample was measured at 5 points, and the average was taken as the sample thickness). Thickness unevenness was determined by the following. Thickness unevenness = maximum thickness / minimum thickness

(15) Evaluation of Leakage of Contents from Hollow Molded Body The hollow molded body molded in (11) above was filled with hot water at 85 ° C., capped by a capping machine, and then the container was laid down and left to stand. I investigated the leak. In addition, the state of deformation of the spout after capping was also examined.

(16) Sensory test The biaxially stretched blow hollow molded article molded in the above (11) was
Distilled water at 70 ° C., which had been boiled and cooled, was placed therein, sealed and held for 30 minutes, cooled to room temperature, and allowed to stand at room temperature for 1 month. After opening, the flavor, smell and the like were tested. As a blank for comparison,
Uses distilled water. The sensory test was carried out by 10 panelists according to the following criteria, and the average values were compared. (Evaluation criteria) 0: No off-taste or odor 1: Slight difference from blank 2: Slight difference from blank 3: Sensible difference from blank 4: Very large difference from blank feel

(17) Sodium content, calcium content, magnesium content, and silicon content in the introduced water introduced into the chip forming step, the introduced water was collected, and the 1G1 glass filter manufactured by Iwaki Glass Co., Ltd.
After filtering with, the filtrate was measured with an inductively coupled plasma emission spectrometer manufactured by Shimadzu Corporation.

(18) Total oxygen demand (TOD) (ppm) of the introduced water introduced into the chip forming step The introduced water filtered by the glass filter used in the above (17) is in accordance with the method of JIS-K0101. To measure.

(19) Particle Size and Number of Particles in Introduced Water Introduced to Chiping Process Light-shielding particle measuring instrument HIAC / ROYCO. Manufactured by Pacific Scientific Company. Counter 4
The measurement was performed using a 100 type and a sampler 3000 type.

(20) Ethylene glycol content in cooling water (hereinafter referred to as "EG content in water") Ethylene glycol content in cooling water supplied to the chip forming step.
Of high concentration gas chromatograph method
Displayed in m. For example, in the case of a strand cutter, it is supplied as cooling water supplied to cool the strands, and in the case of an underwater cutter, it is supplied as cooling water which comes into contact when the melt is extruded from a die into water and cut. Water is the target.

(21) Content of monohydroxyethyl terephthalate in cooling water (hereinafter, "MHET content in water")
And bishydroxyethyl terephthalate content (hereinafter referred to as "BHET content in water") The cooling water supplied to the chip formation step was measured by a high performance liquid chromatography method, and the concentration was expressed in ppm.

(22) Measurement of the Number of Particles in Gas Contacting Polyester The gas sent by a blower for forcibly sending the gas and passing through the gas cleaning device is branched from the main gas stream before contacting with the polyester. It is introduced into a particle measuring instrument and measured.
The measurement is repeated 5 times, the average value is obtained, and the number per 1 cubic foot of gas is calculated. As the particle measuring instrument, a light scattering type particle measuring instrument KC-01B manufactured by Rion Co., Ltd. was used.

(Example 1) A slurry of high-purity terephthalic acid and ethylene glycol was continuously fed to a continuous first esterification reactor containing a reactant in advance, and the mixture was stirred under a pressure of about 1%. The reaction was performed at 250 ° C. and 0.5 kg / cm ² G for an average residence time of 3 hours. This reaction product was sent to the second esterification reactor and stirred at about 260 ° C. at 0.05 kg / cm 2.
^The reaction was performed with ² G to a predetermined degree of reactivity. Further, crystalline germanium dioxide was heated and dissolved in water, ethylene glycol was added thereto, and a heat-treated catalyst solution and ethylene glycol solution of phosphoric acid were separately fed continuously to the second esterification reactor. . This esterification reaction product is continuously fed to the first polycondensation reactor and stirred at about 265 ° C.
Polycondensation is performed at 25 torr for 1 hour, then at the second polycondensation reactor under stirring at about 265 ° C. for 3 hours at 3 torr, and further at the final polycondensation reactor at about 275 ° C. for 0.5 to 1 torr for 1 hour. It was

Filter industrial water (derived from underground river water)
Approximately 480 particles / 10 m of particles having a particle size of 1 to 25 μm that have been treated with a filtration device, an activated carbon adsorption device and an ion exchange device
1, sodium content is 0.05 ppm, magnesium content is 0.03 ppm, calcium content is 0.03
ppm, silicon content 0.09 ppm, TOD 0.3
~ 1 ppm of introduced water is introduced into the cooling water storage tank of the chipping process. Molten polycondensed PET extruded continuously in the form of strands is chipped while being cooled with cooling water of 20 ° C. from the above tank, and the discharged water from the chipping step is a continuous filter having a filter medium made of paper and having a thickness of 30 μm. After the treatment with the fine removal device and the activated carbon adsorption tower for adsorbing ethylene glycol and the like, almost the entire amount is returned to the cooling water storage tank and mixed with the introduced water. This cooling water is continuously circulated and the shortage is replenished from outside the system to be used as cooling water. EG content in cooling water is 3.2 pp
m, BHET content in water is 1.0 ppm, and MH in water
The ET content was 2.1 ppm. The amount V of cooling water is about 2800 cm ³ / sec, and the surface area S of the molten polycondensed polyester to be cooled is about 3300 cm ² / sec.
And the ratio (V / S) was about 0.85. The melt polycondensation PET having an intrinsic viscosity of 0.55 was transported to a vibrating sieving step and an air stream classifying step to remove fines and film-like substances, thereby reducing the fines content to about 30 ppm or less.

This resin was overheated and charged into a cleaned continuous solid phase polymerization apparatus. About 155 in a nitrogen atmosphere
Crystallization at ℃, preheat to about 200 ℃ under nitrogen atmosphere, then send to continuous solid-state polymerization reactor about 205 under nitrogen atmosphere.
Solid state polymerization was carried out at ° C. After the solid phase polymerization, the sieving process and the fines removing process were continuously performed to remove the fines and fill the container for storage. In addition, a plug-type transportation method was used for all transportation of the melt polycondensation PET chips in the manufacturing process.
In addition, as air for sending the melt polycondensation PET chip to the solid-state polymerization step, and air for contacting the solid-state polymerization PET chip with the chip before filling the storage container, JIS B 9908 is used.
(1991) Type 3 PET non-woven filter unit equipped with an air purifier and JIS B 9908 (1)
991) Type 1 particle collection rate 99% or more of the HEPA filter unit equipped with an air purifier is used to filter the air (particle size 0.3 ~ 5μm about 550 particles / cubic feet) did. Air filtered in the same manner as in Examples 2 to 3 was used.

PE obtained 3 months after the start of continuous production
The T was evaluated. The obtained PET had an intrinsic viscosity of 0.75 deciliter / gram, a DEG content of 2.6 mol%, an acetaldehyde content of 3.0 ppm, a cyclic trimer content of 0.37% by weight, and a density of 1 .4018 g / cm
3, the content of fine was about 39 ppm, and the peak temperature of the highest melting peak temperature of fine was 245 ° C. The Ge residual amount of the catalytic metal measured by atomic absorption spectrometry was 43 ppm, and the P residual amount was 30 ppm.
The PET was evaluated using a molded plate and a biaxially stretched molded bottle. The haze of the formed plate was 4.6%, and the spherulite number of the formed plate was 3.6 × 10 ⁹ pieces / m ² . The density of the bottle cap portion was 1.378 g / cm ^3, which was a value with no problem, and the foreign matter of the hollow molded article was “◎ (no foreign matter)”.
And there was no problem. Also, in the leak test of the contents,
There was no problem and there was no deformation of the mouth plug. The body haze of the obtained bottle was 1.0%, and the haze unevenness was 1.1. The AA content of the bottle was 21.0 ppm, and the sensory test result was 0.8, which was a value with no problem.

Example 2 Melt polycondensation and solid phase polymerization were continuously carried out under the same conditions as in Example 1 to obtain solid phase polymerized PET at 6 months of continuous production. The PET obtained has an intrinsic viscosity of 0.7.
5 deciliter / gram, DEG content 2.7 mol%, acetaldehyde content 3.2 ppm, cyclic trimer content 0.38% by weight, density 1.4018 g /
cm ³ , fine content is about 50 ppm, and the peak temperature of the highest melting peak temperature of fine is 247.
It was ℃. Ge of catalytic metal measured by atomic absorption spectrometry
The residual amount was 45 ppm, and the residual P amount was 30 ppm. The intrinsic viscosity of the melt polycondensed PET was 0.55. The PET was evaluated using a molded plate and a biaxially stretched molded bottle. The haze of the formed plate was 5.3%, and the spherulite number of the formed plate was 5.5 × 10 ⁹ pieces / m ² . The density of the bottle cap portion was 1.380 g / cm ^3, which was a value with no problem, and the foreign matter of the hollow molded body from PET at each time point described above was “○ (very small amount of foreign matter)”. And there was no problem. In addition, in the leak test of the contents, there was no problem and the mouth plug was not deformed. The body haze of the obtained bottle was 1.2%, and the haze unevenness was 1.1. The AA content of the bottle was 20.5 ppm, and the result of the sensory test was 0.9, which was a problem-free value.

Example 3 The esterification conditions were slightly changed,
Further, a melt polycondensation PET extruded in a strand shape having an intrinsic viscosity of 0.69 was obtained in the same manner as in Example 1 except that the final melt polycondensation time was extended. The chips were cut under the conditions and methods described in 1. The melt polycondensed PET was transported to a vibrating sieving step and an air stream classifying step to remove fines and film-like substances, whereby the fine content was reduced to about 50 ppm or less. In addition, industrial water (derived from river underflow water) was treated with a filter-filtration device, an activated carbon adsorption device and an ion exchange device,
Approximately 400 particles / 10 ml having a particle size of 1 to 25 μm, sodium content of 0.04 ppm, magnesium content of 0.02 ppm, calcium content of 0.03 ppm,
Silicon content is 0.09ppm, TOD is 0.3-1pp
m of introduced water was introduced into the cooling water storage tank in the chip forming process.

This resin was overheated and charged into a cleaned continuous solid phase polymerization apparatus. About 155 in a nitrogen atmosphere
Crystallization at ℃, preheat to about 200 ℃ under nitrogen atmosphere, then send to continuous solid-state polymerization reactor about 207 under nitrogen atmosphere.
Solid state polymerization was carried out at ° C. After solid phase polymerization, fine particles were removed by continuous treatment in a sieving step and a fine particle removing step. The PET obtained 3 months after the start of continuous production was evaluated. The obtained PET had an intrinsic viscosity of 1.18 deciliter / gram, a DEG content of 3.2 mol%, an acetaldehyde content of 3.4 pm, and a cyclic trimer content of 0.0.27.
The weight%, the density was 1.4028 g / cm ³ , the fine content was about 41 ppm, and the peak temperature of the highest melting peak temperature of fine was 247 ° C. The residual amount of Ge of the catalytic metal measured by atomic absorption spectrometry is 57 ppm,
The residual P amount was 35 ppm. In addition, a plug-type transportation method was used for all transportation of the melt polycondensation PET chips in the manufacturing process. The PET was evaluated using a molded plate and a direct blow bottle. The haze of the formed plate is 3.3%, and the spherulite number of the formed plate is 2.1 × 10 ⁹ pieces / m ^2.
Met. A 300 ml container was molded by a direct blow molding machine, and foreign matter was inspected according to the evaluation criteria of (9). The foreign matter was "○ (the amount of foreign matter is very small)", the transparency judged by the naked eye was good, and the product value was good, and there was no problem.

(Example 4) The content of fines in the melt polycondensation PET (6th month of continuous production) charged to the solid phase polymerization step was about 330ppm, and the fine content of solid phase polymerization PET added to the sheet molding step was included. Solid phase polymerization was carried out in the same manner as in Example 1 except that the process conditions were changed so that the amount was about 3500 ppm, and the intrinsic viscosity was 0.73 deciliter / gram.
PET having an acetaldehyde content of about 10 ppm and a cyclic trimer content of 0.55% by weight was obtained. A sheet having a thickness of 0.5 mm was obtained using a homemade sheet film-forming machine using this PET. A film was formed while filtering with a filter in which three 500-mesh stainless wire meshes were stacked, but the pressure gauge installed in front of the wire mesh filter showed a slight rise, and almost no foreign matter was found in the obtained sheet. . The foreign matter inspection was performed by visually observing a sheet (width of about 1 m × 10 m) to measure the number of foreign matter having a size of 0.5 mm or more.

(Comparative Example 1) Industrial water was used as it is as cooling water for chip formation without using the ion exchange device used in Example 1, and the water used for cooling was not subjected to any treatment. A melt polycondensed PET having an intrinsic viscosity of 0.55 was obtained in the same manner as in Example 1 except that the PET was recycled. This melt polycondensed PET was put into an overhole and a cleaned continuous solid phase polymerization apparatus without being subjected to a treatment for removing fines and the like, and solid phase polymerization was carried out in the same manner as in Example 1 to obtain. PET
Was subjected to molding without removing treatment such as fines. In addition,
The low-density transportation method was used to transport the melt-polymerized PET and the solid-state polymerized PET in the manufacturing process.

Particles having a particle size of 1 to 25 μm contained in the industrial water introduced as cooling water at the time of chip formation are about 49230.
0-654000 pieces / 10 ml, sodium content 4.3-7.5 ppm, magnesium content 1.0-
2.0 ppm, calcium content 6.2-7.1 pp
m, the silicon content was 10.1 to 15.5 ppm, and the TOD was 180 ppm. EG content of circulated cooling water in water is 145 ppm, BHET content in water is 1
The MHET content in water was 30 ppm and 150 ppm in water. Further, the temperature of the cooling water is 5 ° C., and the water amount V is about 88.
The surface area S of the melt-polycondensed polyester cooled at 00 cm ³ / sec was about 3300 cm ² / sec, and the ratio (V / S) was about 2.7.

PE obtained 3 months after the start of continuous production
The T was evaluated. The obtained PET had an intrinsic viscosity of 0.75 deciliter / gram and an acetaldehyde content of 2.8.
ppm, content of cyclic trimer is 0.37% by weight, density is 1.4019 g / cm ³ , fine content is about 280
It was 0 ppm. The peak temperature on the highest temperature side of the fine peak temperature was 277 ° C. In addition, a considerable amount of brown, grayish, and other foreign substances were present in the fine particles, and metals such as calcium, magnesium, and silicon were detected by X-ray microanalyzer analysis. These PETs were evaluated using a molded plate and a biaxially stretched molded bottle. The haze of the molded plate is 37.6.
%, And the spherulite number of the formed plate was 48.9 × 10 ⁹ pieces / m ² . The density of the mouth of the bottle is 1.398 g / cm ^3.
The foreign matter of the hollow molded article was “× (existing in large numbers)” and had no commercial value. Also,
In the leak test of the contents, leakage of the contents was found. The body haze of the obtained bottle was very bad at 18.3%,
In addition, the thickness of the portion where the foreign matter exists is abnormally thick due to the foreign matter serving as a core, which is a problem. AA content of bottle is 2
Although it was a normal value of 1.0 ppm, the sensory test result was 3.8, which was a very bad problem.

(Comparative Example 2) Sheet molding evaluation was performed on PET after 6 months of continuous production manufactured in the same manner as in Comparative Example 1. In addition, melt polycondensation PE to be added to the solid phase polymerization step
The content of fines etc. of T (6th month of continuous production) is about 23
00 ppm, solid-state polymerization P to be added to the sheet forming process
The fine content of ET was about 7,000 ppm and the intrinsic viscosity was 0.74 deciliter / gram. A sheet was produced in the same manner as in Example 4, but the back pressure suddenly increased in one day's production, the wire net was broken, and normal production was impossible. In addition, the obtained sheets of foreign matter were innumerable and had no commercial value.

[0197]

[Table 1]

[0198]

EFFECTS OF THE INVENTION According to the present invention, a hollow molded article containing almost no foreign matter and excellent in transparency and flavor is provided.
Further, it is possible to advantageously obtain a polyester which is less likely to be soiled with a mold during the molding of a molded body, or a polyester which is less likely to be clogged with a filter during film formation and spinning and has improved operability.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuki Yamauchi             1-1, Nada-cho, Iwakuni-shi, Yamaguchi Toyobo Co., Ltd.             Company Iwakuni Factory (72) Inventor Yoshitaka Eto             20 No. 248 Takashiro, Shiga Town, Shiga District, Shiga Prefecture F term (reference) 4J029 AA03 AC01 AC02 AD01 AE01                       AE02 AE03 BA03 CB06A                       KD03 KD17 KE05 KE12 KE15                       KH05 KH08

Claims (10)

[Claims] 1. A low-polymer production step (a) for esterifying or transesterifying a dicarboxylic acid containing terephthalic acid or an ester-forming derivative thereof with a glycol containing ethylene glycol or an ester-forming derivative thereof.
The melt polycondensation step (b) of melt polycondensing the low polymer obtained in the low polymer production step, the melt polycondensed polyester obtained in the melt polycondensation step, the sodium content (N), The content (M) of magnesium, the content (S) of silicon and the content (C) of calcium are the following (1).
To (4) Chiping step of chipping while cooling with cooling water satisfying at least one of (4) N ≤ 1.0 (ppm) (1) M ≤ 0.5 (ppm) (2) S ≤ 2.0 (ppm) (3) C ≤ 1.0 (ppm) (4) and melt polycondensation obtained in the chipping step and having an intrinsic viscosity of 0.30 to 0.80 deciliter / gram. A solid-state polymerization step (d) of solid-state polymerizing polyester, the method for producing polyester. 2. The method for producing polyester according to claim 1, wherein the total oxygen consumption (TOD) of the introduced water introduced into the chipping step (c) from outside the system is 100 ppm or less. 3. When the water obtained by mixing at least a part of the water discharged from the chipping step (c) with fresh introduced water from outside the system as cooling water in the chipping step (c) is cooled. The ethylene glycol content, the monohydroxyethyl terephthalate content, and the bishydroxyethyl terephthalate content in the water are each maintained at 100 ppm or less, according to any one of claims 1 and 2. A method for producing the described polyester. 4. The method for producing a polyester according to claim 1, wherein at least water treated with an ion exchange device is used as the cooling water in the chipping step (c). 5. The water temperature of the cooling water in the chipping step (c) is 7 to 50 ° C., and the water amount V (cm ³ / se) of the cooling water.
Surface area S of melt polycondensed polyester cooled with c)
A chip is formed under the condition that the ratio (V / S) of (cm ² / sec) satisfies the following (5).
5. The method for producing a polyester according to any one of 4 to 4. 0.1 ≦ (V / S) ≦ 2.0 (5) 6. An intermediate step (e) between the chip forming step (c) and the solid phase polymerization step (d), or between the solid phase polymerization step (d) and the solid phase polymerization step (d). A feature is that a fine etc. removing step (h) for removing fines and / or film-like substances is added to at least one intermediate step of the intermediate step (g) with the subsequent step (f) installed later. The method for producing a polyester according to any one of claims 1 to 5. 7. A fine content, a film-like material content, or a total content of a fine content and a film-like material content of the melt polycondensed polyester supplied to the solid phase polymerization step (d). One content, or at least one of the fine content of the solid-phase polymerized polyester supplied in the subsequent step (f), the film-like material content, or the total content of the fine content and the film-like material content. One content is 500 ppm or less, The manufacturing method of the polyester in any one of Claims 1-6 characterized by the above-mentioned. 8. The method according to claim 1, wherein the subsequent step (f) is at least one of a contact treatment step with water and a thermoplastic resin compounding step.
The method for producing a polyester according to any one of 1. 9. A polyester is used in at least one of the melt polycondensation step (b), the chip forming step (c), the solid phase polymerization step (d), the post step (f), and the fines removing step (h). The gas to be contacted has a particle size of 0.3-5 μ
The method for producing a polyester according to any one of claims 1 to 8, wherein a gas introduced from outside the system, in which m particles are 1,000,000 particles / cubic foot or less, is used. 10. The polyester has an intrinsic viscosity of 0.60.
~ 2.00 deciliters / gram, acetaldehyde content of 10 ppm or less, cyclic trimer content of 0.5% by weight or less, and spherulites formed when a molded plate obtained by injection molding is crystallized by heating. The number is 1 × 10 ⁹ to 15 × 10 ⁹ pieces / m
The polyester according to claim 1, wherein the polyester is in the range of ² .