KR101159842B1 - Polyester resin and method for producing the same - Google Patents

Abstract

More particularly, the present invention relates to a polyester resin and a process for producing the polyester resin, and more particularly, to a process for esterifying or esterifying a dicarboxylic acid and a diol component, and a process for producing a polyester resin by a polycondensation reaction and a solid phase polymerization Reacting a phosphorus compound represented by the following general formula (1) with an initial or terminal or polycondensation reaction of the esterification reaction or esterification exchange reaction step so as to have a phosphorus atom content of 0.1 to 25 ppm based on the theoretical yield of the polyester resin The present invention relates to a polyester resin to be added at an early stage and a method for producing the same.

Formula 1

In the general formula (1), R 1, R 2, and R 3 are the same or different from each other and are hydrogen or an alkyl group having 1 to 10 carbon atoms.

According to the present invention, the use of a small amount of a specific phosphorus compound improves the activity of the titanium catalyst, in particular, its activity during solid-phase condensation, thereby improving the thermal stability and reducing the content of yellowing and byproducts. It is possible to produce a polyester resin more suitable for the production of various food containers and the like.

Polyester resin, titanium catalyst, intrinsic viscosity, yellowing, thermal stability, activity

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin and a method for producing the same,

More particularly, the present invention relates to a polyester resin and a method for producing the polyester resin, and more particularly, to a polyester resin using a titanium catalyst, A polyester resin capable of economically producing a polyester resin which is sufficiently improved in polycondensation activity, is excellent in thermal stability, is free from yellowing and has a reduced content of byproducts and improved physical properties, and a method for producing the same.

In general, polyester resins are widely used for the production of various containers, films, fibers and the like because of their low cost and excellent mechanical and chemical properties and gas barrier properties. Various catalysts have been used for polymerization of such polyester resins. However, the antimony catalyst, which is a widely used catalyst, has a problem that it contains a heavy metal which is not environmentally preferable, and it is required to use a large amount of hundreds of ppm relative to the resin in order to obtain an appropriate reactivity. The cleaning cycle of the equipment is shortened due to precipitation of antimony in the molding process, and in particular, when molding into a container, antimony is extracted due to high temperature contents. Another catalyst, germanium catalyst, is environmentally friendly, but it is expensive and not commercially useful. As a catalyst capable of improving the problems of the antimony and germanium catalysts, a titanium catalyst suitable for environmentally friendly, low cost and excellent reactivity and suitable for polymerization reaction even if the content of less than several ppm is added has been attracting attention, Has a disadvantage in that the degree of sulfur change of the resin is large when added in a large amount and the activity decreases when added in small amounts. Particularly, in the case of condensation in a solid phase, there is a problem that its activity is significantly lowered in comparison with other catalysts. In addition, if the activity of titanium is not controlled by using a suitable stabilizer, by-products such as acetaldehyde and oligomers are produced in a large amount, which is not suitable for various food containers.

U.S. Patent No. 5,744,572 discloses a phosphorus (P) compound that improves the condensation activity in solid phase but has a disadvantage in that the added amount thereof is too high to several hundred ppm.

As a result, the present invention has been made to solve the above problems. As a result, it has been found that, when a polyester resin is prepared using a titanium catalyst, the activity of the titanium catalyst can be sufficiently controlled by adding a small amount of a specific phosphorus compound, It was found that polyester resin can be produced economically by reducing the amount of byproducts produced without increasing the yellowing by improving the activity of the addition, and the present invention has been completed on the basis thereof.

Accordingly, an object of the present invention is to provide an economical method for producing a polyester resin in which activity and reactivity of a titanium catalyst are improved by using a specific phosphorus compound in a small amount, and thus the thermal stability is excellent and the production of by- .

Another object of the present invention is to provide a polyester resin produced by the above method.

According to another aspect of the present invention, there is provided a method for producing a polyester resin comprising the steps of: subjecting a dicarboxylic acid and a diol component to an esterification reaction or an esterification exchange reaction; and subjecting the reaction product to a polycondensation reaction and a solid phase polymerization reaction in the presence of a titanium catalyst Wherein the phosphorus compound represented by the following general formula (1) is reacted at an initial stage of the esterification reaction or the esterification reaction stage or at the beginning of the terminal or polycondensation reaction such that the phosphorus atom is 0.1 to 25 ppm based on the theoretical amount of the polyester resin .

Formula 1

In the general formula (1), R 1, R 2, and R 3 are the same or different from each other and are hydrogen or an alkyl group having 1 to 10 carbon atoms.

The resin of the polyester for achieving another object of the present invention can be obtained by the above-mentioned method.

Hereinafter, the present invention will be described in more detail.

As described above, when the dicarboxylic acid and the diol are subjected to the esterification reaction or the transesterification reaction, and then the polymerization is carried out using the titanium catalyst to produce the polyester resin, the activity of the titanium catalyst, in particular, The present invention provides a method for producing a polyester resin having excellent thermal stability, reduced production of by-products, and is free from yellowing and having excellent color, by adding a small amount of a specific phosphorus compound.

Hereinafter, a method for producing the polyester resin of the present invention will be described in more detail.

First, a step of producing a low-condensation product by performing an esterification reaction or an ester exchange reaction with a dicarboxylic acid and a diol is carried out. This step can be carried out by an esterification reaction or an ester exchange reaction for producing a conventional polyester resin.

Examples of the dicarboxylic acid component include terephthalic acid and its ester-forming derivative, phthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, phenylene dioxydicarboxylic acid, 4,4- Diphenyl dicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4-diphenyl ketone dicarboxylic acid, 4,4-diphenyl sulfone dicarboxylic acid, 2,6-naphthalene dicarboxylic acid Alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid, aromatic dicarboxylic acids such as dodecanedicarboxylic acid, dodecanedicarboxylic acid, anddicarboxylic acid, Aliphatic dicarboxylic acids and ester-forming derivatives thereof may be used, and one or more copolymerized compounds of the above compounds may be used.                     

Examples of the diol component include aliphatic diols such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentyl glycol, diethylene glycol, and polyethylene glycol, Alicyclic diols such as 2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexane dimethylol and 1,4-cyclohexanedimethanol, xylene glycol 4,4-dihydroxy biphenyl, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis And aromatic diols such as 2,2-bis (4-hydroxyphenyl) sulfone may be used. The aromatic diols may be used alone or in combination with two or more kinds of these diols. May be used.

The content ratio of the dicarboxylic acid and the diol, which are reactants in the esterification reaction or the transesterification reaction, is preferably 1.05 to 2 moles, more preferably 1.05 to 1.4 moles, of the diol component per mole of the dicarboxylic acid component, It is mall. If the content of the diol component is too large, side reactions may be promoted and undesirable side products such as diethylene glycol may be formed. When the content of the diol component is too small, the esterification reaction may be insufficient or the reaction time may be delayed There is a problem.

The ester reaction or transesterification reaction can be carried out under the process conditions of a conventional ester reaction or transesterification reaction, and can be carried out, for example, at a temperature of 230 ° C to 260 ° C and a pressure of 0.5 to 2 kgf / cm 2 .

In the process for producing a polyester resin according to the present invention, a phosphorus (P) compound can be preferably introduced at the beginning or end of an esterification reaction or an ester exchange reaction, or at the beginning of a polycondensation reaction. ) Compound is a compound represented by the following formula (1) mentioned in the above-mentioned U.S. Patent No. 5,744,572, and may be used by mixing a small amount of other phosphorus (P) compounds as usual, It is advantageous not to. Typical phosphorus (P) compounds include phophorous acid, phophoric acid, triphenyl phosphate, trimethyl phosphate (TMP), triethyl phophate (TMP), tributyl But are not limited to, tributyl phsphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate, trinonylphenyl phosphate, benzylphosphoric acid, methylphosphoric acid methyl ester, Esters, and mixtures thereof.

Formula 1

In the general formula (1), R 1, R 2, and R 3 are the same or different from each other and are hydrogen or an alkyl group having 1 to 10 carbon atoms. Preferably, the phosphorus compound used in the present invention is Carboxyethylene Phosphonic acid (hereinafter referred to as CEPA) in which R 1, R 2 and R 3 in the general formula (1) are all hydrogen. The content of the phosphorus compound represented by the formula (1) is preferably 0.1 ppm to 25 ppm of phosphorus (P) atoms, more preferably 0.1 to 20 ppm, based on the theoretical resin content. If the content of the phosphorus compound is less than 0.1 ppm, the effect of improving the titanium catalyst activity is insignificant.

Next, a polycondensation reaction step of a low-condensation product, which is the product of the esterification reaction, is carried out in the presence of a titanium catalyst. Examples of the titanium catalyst include tetra-n-propyl titanate, tetra-I-propyl titanate, tetra-n-butyl titanium titanate, tetra-t-butyl titanate, titanium acetate, titanium hydroxide, bicarbonate titanium catalyst or a mixture thereof may be used. As the coloring agent, a cobalt compound, an organic toner, Or a mixture thereof may be added. If necessary, a hindered phenol-based compound may be added as an antioxidant.

The polycondensation reaction can also be carried out under the polycondensation reaction conditions of a conventional polyester resin production method, and can be carried out at a temperature of, for example, 250 to 300 ° C, preferably 260 to 300 ° C and a reduced pressure of 0.5 torr Preferably, after the catalyst and the additive are added, the reaction may be carried out at a reduced pressure sequentially at a temperature of 250 to 300 ° C.

The polycondensation reaction is carried out for a period of time during which the intrinsic viscosity of the polyester polycondensation reaction product reaches a desired level, preferably from 0.3 to 1.0 dl / g, more preferably from 0.4 to 0.8 dl / g, / g < / RTI > is reached. If the intrinsic viscosity exceeds 1.0 dl / g, the by-products such as acetaldehyde and cyclic trimer are increased. If the intrinsic viscosity is less than 0.3 dl / g, the mechanical strength of the polyester resin is poor, When the intrinsic viscosity is further increased by carrying out the solid phase polymerization reaction, the solid phase polymerization time is prolonged, which is economically disadvantageous.

In the present invention, in order to increase the intrinsic viscosity of the polyester polycondensate, which is a product of the polycondensation reaction, the polyester polycondensate may further be subjected to a solid phase polymerization reaction.

As described above, the polyester resin produced by the method according to the present invention can be molded into a final product such as a container, a film, or a fiber by a conventional method such as injection blow molding, spinning, casting, Trimer and the like, and thus is particularly suitable for the production of various food containers such as bottles.

The following examples and comparative examples are intended to illustrate the present invention further but are not to be construed as limiting the scope of the present invention.

Hereinafter, the method for measuring the physical properties and the post-processing method of the polyester prepared in Examples and Comparative Examples are as follows.

1) Condensation in solid phase: 100 g of the polyester resin on the chip was weighed and filled in a tube tube. The tube was covered with a stopper, and the tube was immersed in an oil bath. While flowing nitrogen gas at a flow rate of 2 liters / minute, And allowed to stand for 16 hours. The tube was taken out from the oil bath and cooled to room temperature under a nitrogen stream. 10 g of the upper and lower portions were carefully removed by opening the tube stopper, and 80 g of the middle portion was separately sampled to measure the intrinsic viscosity of the resin.

2) Intrinsic viscosity (hereinafter referred to as IV): A resin sample was subjected to freeze-grinding using liquid nitrogen, and 0.36 g of a sample was added to o-chlorophenol solvent at 150 ° C. , The relative viscosity (? Rel) between the solution and the undiluted solution was measured at 35 占 폚 using a Ube load viscometer, and the specific viscosity? Sp (=? Rel-1) The intrinsic viscosity value (IV) of the resin was converted using the Huggins equation.

3) Content of metal atoms: After dissolving 2 g of the sample in mixed acid, the metal atom content was determined by inductively coupled plasma emission spectroscopy.

4) Resin color tone: After a predetermined amount of resin sample was filled in a colorimetric cell in the circumference, the saturation color coordinate b of the hunter in the Lab colorimetric system was measured three times by reflection method to obtain an average value.

5) Preparation of preform and bottle The resin was vacuum dried at 170 ° C for 12 hours and charged into an injection molding machine (ASB150, Nissei Machine) to prepare preforms of 145 mm in height, 28 mm in outer diameter, 4 mm in thickness and 48 g in weight 275 DEG C, molding cycle 23 seconds).

6) Acetaldehyde (AA) content: After the preform was frozen and pulverized, about 1 g of the pulverized product was placed in a 20 ml container, and the amount of acetaldehyde obtained by heating at 150 캜 for 40 minutes was measured by gas chromatography. And the absolute value thereof was obtained by comparing with the diluent value of aldehyde.

Example 1                     

Preparation of polyethylene terephthalate resin

A slurry reaction solution of 9960 parts by weight (about 60 moles) of terephthalic acid and 4650 parts by weight (about 75 moles) of ethylene glycol was placed in an esterification reactor and the temperature of the reactor was set to 250 ° C. kgf / cm < 2 >. During the reaction, a mixture of water and a small amount of ethylene glycol in the esterification reaction was distilled out of the reactor through a distillation column, After completion of the esterification reaction, CEPA (Carboxyethylene Phosphonic Acid) was added in an amount of 10 ppm of phosphorus (P) based on the theoretical amount of polyester resin, and as a polycondensation catalyst, titanium alkoxide After the addition of tetra-n-butyl-titanate so that the titanium atom is at 10 ppm based on theoretical resin amount, the product of the esterification reaction The condensation product was transferred to a polycondensation reactor. Next, the polycondensation reaction was carried out at 280 ° C. under 0.5 torr until the intrinsic viscosity (IV) reached 61, and the polycondensation reaction product was allowed to stand at 160 ° C. for 2 hours to crystallize, The reaction product was transferred to a solid-state polymerization reactor. The reaction product was allowed to flow at a flow rate of 2 liters / minute while maintaining nitrogen at 210 캜 for 16 hours, and the physical properties thereof were measured.

Example 2 and Comparative Examples 1, 2, 3, and 4

Preparation of polyethylene terephthalate resin

The procedure of Example 1 was repeated, except that the kind and amount of the phosphorus compound were changed as shown in Table 1 below.                     

The physical properties of the resins prepared from the examples and comparative examples are shown in Table 1 below.

Item Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Stabilizer type CEPA CEPA Phosphoric acid TEP TMP ㅡ Metal atom Ti
(ppm) 10 10 10 10 10 10 P
(ppm) 10 20 10 10 10 0 Melting
Polycondensation IV 0.61 0.60 0.62 0.59 0.60 0.62 elegance
Polycondensation IV 0.81 0.79 0.80 0.80 0.81 0.83 Solid-state time (hr) 15 17 33 24 26 14 Col-b 5.6 5.2 5.2 5.3 5.5 8.5 Preform
Properties AA (ppm) 16 14 12 12 13 21

As shown in the above examples and comparative examples, even when a small amount of phosphorus compound is added according to the production method of the polyester resin of the present invention, the activity of the titanium catalyst, particularly, the activity at the time of solid phase condensation is sufficiently improved, , Acetaldehyde and the like, and is free from yellowing. Thus, it is expected that a polyester resin suitable for a variety of products, especially food container raw materials, can be economically produced.

Claims (4)

A process for producing a polyester resin comprising the step of subjecting a dicarboxylic acid and a diol component to an esterification reaction or an esterification exchange reaction and a polycondensation reaction and a solid phase polymerization reaction of the reaction product in the presence of a titanium catalyst, (CEPA) is added at the initial or terminal stage of the esterification reaction or the esterification exchange step, or at the beginning of the polycondensation reaction so that the phosphorus atom is 0.1 to 25 ppm based on the theoretical amount of the polyester resin ≪ tb > < / TABLE > Formula 1

R1, R2, and R3 in the above formula (1) are each hydrogen. delete A polyester resin produced according to the method of claim 1. A molded article molded from a polyester resin according to claim 3, wherein the molded article is a food container, film, or fiber.