JP2012144744A - Method for producing aliphatic polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aliphatic polyester which has large reaction rate of the melt polycondensation during the production, and little undergoes decomposition of aliphatic diol, and which is transparent, and is excellent in heat resistance, and to provide a method for producing the aliphatic polyester.SOLUTION: In the aliphatic polyester, the intrinsic viscosity ([η] dL/g) is 1.3-2.5, the terminal carboxy group concentration (equivalent/ton) is 5-30, the solution haze (%) is 0.01-2.50, and the color b value is -3.0 to 3.0.

Description

  The present invention relates to a method for producing an aliphatic polyester. Specifically, the present invention relates to an efficient continuous production method of high-quality aliphatic polyester.

  In recent years, awareness of environmental issues such as depletion of fossil fuels and an increase in carbon dioxide in the atmosphere has increased, and in the plastics industry, countermeasures for environmental issues that take into consideration the life cycle from product manufacture to disposal have become urgent. ing.

  Under these circumstances, aliphatic polyesters composed of aliphatic dicarboxylic acids and aliphatic diols have attracted attention as environmentally friendly plastics. Raw material aliphatic dicarboxylic acids (eg, succinic acid and adipic acid) can be produced from plant-derived glucose using a fermentation method, and aliphatic diols (eg, ethylene glycol, propanediol, butanediol) can also be produced from plant-derived materials. Therefore, resource saving of fossil fuel can be achieved. At the same time, the growth of plants absorbs carbon dioxide in the atmosphere, which can greatly contribute to the reduction of carbon dioxide emissions. Furthermore, it is also known to exhibit excellent biodegradability, and it can be said that the aliphatic polyester is a triple-friendly plastic.

  The aliphatic polyester is usually obtained by subjecting an aliphatic dicarboxylic acid and an aliphatic diol to an esterification reaction and a melt polycondensation reaction. These reactions are usually performed by a batch method, a continuous method, or a combination of a batch method and a continuous method. Among these, when mass-producing industrially, the continuous method is advantageous in terms of productivity, quality stability, economy, etc., and those that are mass-produced such as polyethylene terephthalate and polybutylene terephthalate are based on the continuous method. There are overwhelmingly many things.

  The continuous production method of aliphatic polyester is disclosed in Patent Document 1. According to this document, it is disclosed that the reaction temperature of esterification and melt polycondensation is carried out at a prescribed temperature or less. However, the specifically disclosed technique does not necessarily increase the degree of polymerization, and is aliphatic. Since the decomposition of the diol during the reaction is also large, it was not always a satisfactory method.

  Further, Patent Document 2 discloses a step of proceeding an esterification reaction to a predetermined esterification rate at a predetermined reaction temperature to obtain a low molecular weight body having a predetermined weight average molecular weight and a predetermined acid value, and polycondensation at a predetermined reaction temperature to increase the amount. It describes a technique that uses a biaxial continuous polymerization reaction apparatus in a high molecular weight process that includes a molecular weighting process and has a viscosity that exceeds a specific value. However, in the disclosed technique, the esterification reaction time is relatively long, and it is not always an efficient method because it is pelletized before being subjected to a higher molecular weight process than a specific value, and again subjected to a polymerization reactor. It was.

JP 2006-265503 A JP 2006-274253 A

  In view of the above problems, an object of the present invention is to provide a transparent and heat-resistant aliphatic polyester having a high melt polycondensation reaction rate at the time of production, less aliphatic diol decomposition, and a method for producing the same. .

  As a result of studying the above problems, the present inventor has made the temperature and pressure of the esterification reaction, the molar ratio of the aliphatic diol to the aliphatic dicarboxylic acid, and the esterification rate within a specific range in the continuous production of aliphatic polyester. As a result, it was found that an aliphatic polyester having a high melt polycondensation reaction rate, a small decomposition of the aliphatic diol, and a good quality can be produced, and the present invention has been achieved.

  That is, the first aspect of the present invention is a continuous production method of an aliphatic polyester mainly comprising an aliphatic dicarboxylic acid and an aliphatic diol, which obtains a polyester through an esterification reaction and a melt polycondensation reaction, The esterification reaction was carried out at an esterification rate of 80% or more by setting the molar ratio of the aliphatic diol component to the aliphatic dicarboxylic acid component to 1.10 to 2.00, the reaction temperature to 215 to 235 ° C., and the reaction pressure to 50 to 200 kPa. The above-mentioned problems are solved by providing a method for producing an aliphatic polyester, wherein the esterification reaction product is subjected to a melt polycondensation reaction.

  In this embodiment, the melt polycondensation reaction is preferably performed using a titanium compound as a polycondensation reaction catalyst.

  Further, in this embodiment, the polycondensation reaction catalyst is diluted with an aliphatic diol and continuously in the liquid phase of the reaction liquid of the esterification reaction or the polycondensation reaction between the end of the esterification reaction and the end of the polycondensation reaction. It is preferable to add them.

  In this embodiment, it is preferable not to use an esterification reaction catalyst in the esterification reaction.

  In this embodiment, the esterification reaction is preferably performed when the molar ratio of the aliphatic diol component to the aliphatic dicarboxylic acid component is 1.20 to 1.60.

  In this embodiment, the esterification rate in the esterification reaction is preferably 85% or more.

  In the second aspect of the present invention, the intrinsic viscosity ([η] dL / g) is 1.3 to 2.5, the terminal carboxyl group concentration (equivalent / ton) is 5 to 30, and the solution haze (%) is 0.00. An aliphatic polyester having a color b value of -3.0 to 3.0 and a color b value of 01 to 2.50 is provided to solve the above-mentioned problems.

  ADVANTAGE OF THE INVENTION According to this invention, the melt polycondensation reaction rate can be large and the manufacturing method of aliphatic polyester with few decomposition | disassembly of aliphatic diol can be provided. According to this method, since it can be continuously produced stably, it is possible to provide an aliphatic polyester having a stable quality, a transparent and good heat resistance, and, in turn, can contribute to an expanded use of a polyester derived from biomass.

It is the schematic which shows one Embodiment of the esterification reaction process in the manufacturing method of the aliphatic polyester concerning this invention. It is the schematic which shows one Embodiment of the polycondensation process in the manufacturing method of the aliphatic polyester concerning this invention.

  The present invention relates to a method for continuously producing an aliphatic polyester, which contains an aliphatic dicarboxylic acid and an aliphatic diol as main components and obtains a polyester through an esterification reaction and a melt polycondensation reaction. Here, “having aliphatic dicarboxylic acid and aliphatic diol as main components” means that 85 mol% or more of all dicarboxylic acid components constituting the polyester of the present invention is aliphatic dicarboxylic acid, and the polyester of the present invention is It means that 85 mol% or more of the total diol component is an aliphatic diol. Hereinafter, the raw material of the aliphatic polyester and the production method of the present invention will be described in detail.

(1) Aliphatic polyester raw material Specific examples of the aliphatic dicarboxylic acid component that is a raw material for aliphatic polyester include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid. , Azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid, dimer acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid and the like. Further, an acid anhydride may be used as the derivative of the aliphatic dicarboxylic acid, and specific examples thereof include succinic anhydride. These aliphatic dicarboxylic acids and derivatives thereof may be used alone or in combination of two or more. Among these, succinic acid, succinic anhydride, adipic acid, and sebacic acid are preferable, and succinic acid is particularly preferable from the viewpoint of physical properties of the obtained polyester. Succinic acid is preferably 50 mol% or more, more preferably 70 mol% or more, based on the total aliphatic dicarboxylic acid from the viewpoint of the melting point (heat resistance), biodegradability and mechanical properties of the resulting aliphatic polyester. Most preferably, it is 90 mol% or more.

  In addition to the aliphatic dicarboxylic acid, an aromatic dicarboxylic acid may be used in combination as the dicarboxylic acid component. Specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl. And dicarboxylic acid. Aromatic dicarboxylic acids may be used alone or in combination of two or more.

  Specific examples of the aliphatic diol component that is another raw material of the aliphatic polyester include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentane. Diol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, poly Examples include tetramethylene ether glycol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and these may be used alone or in combination of two or more. May be. Among these, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol are preferable, and 1,4-butanediol is particularly preferable from the viewpoint of the physical properties of the resulting polyester. 1,4-butanediol is preferably 50 mol% or more, more preferably 70 mol% or more based on the total aliphatic diol from the viewpoint of the melting point (heat resistance), biodegradability and mechanical properties of the aliphatic polyester obtained. Is more preferably 90 mol% or more.

  In the present invention, the aliphatic polyester may contain other components other than the dicarboxylic acid component and the aliphatic diol component. Examples of other copolymer components include lactic acid, glycolic acid, hydroxybutyric acid, hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, and 2-hydroxyisocaproic acid , Malic acid, citric acid, and oxycarboxylic acids such as esters, lactones, and oxycarboxylic acid polymers of these oxycarboxylic acids; unsaturated carboxylic acids such as maleic acid and fumaric acid; glycerin, trimethylolpropane, pentaerythritol, etc. A trifunctional or higher polyhydric alcohol; a trifunctional or higher polyhydric carboxylic acid such as propanetricarboxylic acid, pyromellitic acid, trimellitic acid, benzophenonetetracarboxylic acid and anhydrides thereof, or an anhydride thereof.

  In particular, a polyfunctional compound such as a trifunctional or higher functional oxycarboxylic acid, a trifunctional or higher polyhydric alcohol, a trifunctional or higher polyvalent carboxylic acid, and the like can be obtained by adding a small amount as a copolymerization component to obtain a highly viscous polyester. preferable. Among these, malic acid, citric acid, and fumaric acid are preferable, and malic acid is particularly preferably used. When adding these trifunctional or more polyfunctional compounds, the amount is preferably 0.001 to 5 mol%, more preferably 0.05 to 0.5 mol%, based on the total dicarboxylic acid component. is there. If the upper limit of this range is exceeded, gel (unmelted product) is likely to be generated, and if it is less than the lower limit, the effect of increasing the viscosity tends to be difficult to obtain.

  In the production method of the present invention, a reaction catalyst can be added by an esterification reaction or a polycondensation reaction in order to accelerate the reaction. However, if an esterification reaction catalyst is present during the esterification reaction, water generated by the esterification reaction may cause the catalyst to produce insoluble precipitates in the reaction product, thereby impairing the transparency of the resulting polyester (ie, increasing haze). Yes, it may become a foreign object. In the esterification reaction, it is preferable not to use a reaction catalyst during the esterification reaction because a sufficient reaction rate can be obtained without an esterification reaction catalyst. When a reaction catalyst is added, the haze may be increased if the catalyst is added to the gas phase part of the reaction tank, and the catalyst may be converted into a foreign substance. Therefore, the reaction catalyst is preferably added to the reaction solution.

  On the other hand, in the polycondensation reaction, it is difficult to proceed without a catalyst, and therefore a catalyst is preferably used. As the polycondensation reaction catalyst, a compound containing at least one of the metal elements of Groups 1 to 14 of the periodic table is generally used. Specific examples of metal elements include scandium, yttrium, samarium, titanium, zirconium, vanadium, chromium, molybdenum, tungsten, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, Examples include strontium, sodium and potassium. Among them, scandium, yttrium, titanium, zirconium, vanadium, molybdenum, tungsten, zinc, iron, and germanium are preferable, and titanium, zirconium, tungsten, iron, and germanium are particularly preferable. Furthermore, in order to reduce the polyester terminal density | concentration which affects the thermal stability of polyester, among the said metals, the periodic table 3-6 metal element which shows Lewis acidity is preferable. Specifically, scandium, titanium, zirconium, vanadium, molybdenum, and tungsten are preferable. Of these, titanium and zirconium are preferable because of easy availability, and titanium is particularly preferable from the viewpoint of reaction activity.

  In the present invention, as a catalyst, a compound containing an organic group such as a carboxylate salt, an alkoxy salt, an organic sulfonate salt, or a β-diketonate salt containing these metal elements, and further, an oxide or halide of the above-described metal, etc. Inorganic compounds and mixtures thereof are preferably used.

As the titanium compound, tetraalkyl titanate and a hydrolyzate thereof are preferable. Specifically, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, Examples include tetracyclohexyl titanate, tetrabenzyl titanate and mixed titanates thereof, and hydrolysates thereof. In addition, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium (diisoproxide) acetylacetonate, titanium bis (ammonium lactate) dihydroxide, titanium bis (ethylacetoacetate) diisopropoxide, titanium (triethanolaminate) Isopropoxide, polyhydroxy titanium stearate, titanium lactate, titanium triethanolamate, butyl titanate dimer and the like are also preferably used. Moreover, the liquid substance obtained by mixing alcohol, an alkaline-earth metal compound, a phosphate ester compound, and a titanium compound is also used. Among these, tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium bis (ammonium lactate) dihydroxide, polyhydroxytitanium stearate , Titanium lactate, butyl titanate dimer, and liquid obtained by mixing alcohol, alkaline earth metal compound, phosphate ester compound, and titanium compound are preferred, tetra-n-butyl titanate, titanium (oxy) acetyl Acetonate, titanium tetraacetylacetonate, polyhydroxy titanium stearate, titanium lactate, butyl titanate dimer, alcohol, alkaline earth metal compound, phosphoric acid ester More preferred are liquids obtained by mixing tellurium compounds and titanium compounds, especially tetra-n-butyl titanate, polyhydroxytitanium stearate, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate and alcohol. A liquid material obtained by mixing an alkaline earth metal compound, a phosphate ester compound, and a titanium compound is preferred.

  Specific examples of the zirconium compound include zirconium tetraacetate, zirconium acetate hydroxide, zirconium tris (butoxy) stearate, zirconyl diacetate, zirconium oxalate, zirconyl oxalate, zirconium ammonium oxalate, potassium potassium oxalate, poly Examples include hydroxyzirconium stearate, zirconium ethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide, zirconium tributoxyacetylacetonate and mixtures thereof. The Among these, zirconyl diacetate, zirconium tris (butoxy) stearate, zirconium tetraacetate, zirconium acetate hydroxide, zirconium ammonium oxalate, potassium zirconium oxalate, polyhydroxyzirconium stearate, zirconium tetra-n-propoxide, Zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide are preferred, zirconyl diacetate, zirconium tetraacetate, zirconium acetate hydroxide, zirconium tris (butoxy) stearate, zirconium ammonium oxalate, zirconium tetra -N-propoxide, zirconium tetra-n-butoxide are more preferred, It preferred because zirconium tris (butoxy) stearate is easily obtained polyester having a high degree of polymerization without colored.

  Specific examples of the germanium compound include inorganic germanium compounds such as germanium oxide and germanium chloride, and organic germanium compounds such as tetraalkoxygermanium. In view of price and availability, germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, and the like are preferable, and germanium oxide is particularly preferable.

  Other metal-containing compounds include scandium carbonate, scandium acetate, scandium chloride, scandium compounds such as scandium acetylacetonate, yttrium carbonate, yttrium chloride, yttrium acetate, yttrium acetate such as yttrium acetylacetonate, vanadium chloride, and vanadium trichloride. Oxides, vanadium acetylacetonate, vanadium compounds such as vanadium acetylacetonate oxide, molybdenum compounds such as molybdenum chloride, molybdenum acetate, tungsten compounds such as tungsten chloride, tungsten acetate, tungstic acid, cerium chloride, samarium chloride, ytterbium chloride, etc. Examples include lanthanoid compounds.

  Further, when a known layered silicate described in “Clay Mineralogy” by Haruo Shiramizu, Asakura Shoten (1995) or the like is used alone or in combination with the above metal compound, the polycondensation rate may be improved. Therefore, such a catalyst system is also preferably used.

  Specific examples of layered silicates include kaolins such as dickite, nacrite, kaolinite, anorokite, metahalloysite, halloysite, serpentine groups such as chrysotile, lizardite, antigolite, montmorillonite, zauconite, beidellite, Smectites such as nontronite, saponite, hectorite, stevensite, vermiculites such as vermiculite, mica, illite, sericite, mica such as sea green stone, attapulgite, sepiolite, palygorskite, bentonite, pyrophyllite, talc And chlorite group.

  In the present invention, the catalyst is preferably in the form of a liquid at the time of polycondensation or a compound that dissolves in an ester low polymer or polyester because the polymerization rate is increased when it is melted or dissolved during polycondensation. The polycondensation is preferably carried out without a solvent, but separately from this, a small amount of solvent may be used to dissolve the catalyst. Examples of the solvent for dissolving the catalyst include alcohols such as methanol, ethanol, isopropanol, and butanol, diols such as ethylene glycol, butanediol, and pentanediol, ethers such as diethyl ether and tetrahydrofuran, and nitriles such as acetonitrile. , Hydrocarbon compounds such as heptane and toluene, water and mixtures thereof. Among them, it is preferable to use an aliphatic diol which is a main component of the aliphatic polyester to be produced as the solvent for dissolving the catalyst because the polycondensation reaction can be carried out substantially without a solvent. The solvent for dissolving the catalyst is used so that the catalyst concentration is usually 0.0001% by mass or more and 99% by mass or less.

  Further, the amount of catalyst added when using a metal compound as the polycondensation catalyst, the lower limit is usually 0.1 ppm or more, preferably 0.5 ppm or more, more preferably 1 ppm or more, as the amount of metal with respect to the produced polyester. The upper limit is usually 3000 ppm or less, preferably 1000 ppm or less, more preferably 250 ppm or less, and particularly preferably 130 ppm or less. Too much catalyst is not only economically disadvantageous, but the reason is not yet clear, but the carboxyl group terminal concentration in the polyester may increase, so the carboxyl group terminal amount and residual catalyst concentration The increase in the temperature may reduce the thermal stability and hydrolysis resistance of the polyester. On the other hand, if the amount is too small, the polymerization activity is lowered, and accordingly, thermal decomposition of the polyester is induced during the production of the polyester, making it difficult to obtain a polyester having practically useful physical properties.

  The position of addition of the catalyst to the reaction system is not particularly limited as long as the catalyst is present during the melt polycondensation reaction step, and may be added when the raw material is charged, but under a situation where a large amount of water is present or generated. When the catalyst coexists, the catalyst is deactivated and foreign matter may be deposited, which may impair the quality of the product. Therefore, it is preferably added after the esterification reaction step. Particularly preferably, it is continuously added to the liquid phase of the reaction liquid of the esterification reaction or the polycondensation reaction between the end of the esterification reaction and the end of the polycondensation reaction.

(2) Production method of aliphatic polyester Hereinafter, the aliphatic polyester according to the present invention using succinic acid as an aliphatic dicarboxylic acid, 1,4-butanediol as an aliphatic diol, and malic acid as a polyfunctional compound are used as raw materials. Preferred embodiments of the manufacturing method will be described with reference numerals in the accompanying drawings appended thereto, but the present invention is not limited to the illustrated embodiments.

  FIG. 1 is a schematic view showing an embodiment of an esterification reaction step in the present invention, and FIG. 2 is a schematic view showing an embodiment of a polycondensation step in the present invention.

  In FIG. 1, succinic acid and malic acid as raw materials are usually mixed with 1,4-butanediol (may be represented as BG) in a raw material mixing tank (not shown), The liquid is supplied to the esterification reaction tank A. Moreover, when adding a catalyst at the time of esterification reaction, after making it the solution of 1, 4- butanediol in a catalyst adjustment tank (not shown), it is supplied from the esterification reaction tank catalyst supply line 15.

  Here, the lower limit of the molar ratio of the aliphatic diol component to the aliphatic dicarboxylic acid component in the esterification reaction tank A is 1.10, preferably 1.12, more preferably 1.15, and particularly preferably 1. 20. The upper limit is 2.00, preferably 1.80, more preferably 1.60, particularly preferably 1.55. If the amount is less than the lower limit, the esterification reaction tends to be insufficient, and the polycondensation reaction, which is a reaction in the subsequent step, is difficult to proceed, making it difficult to obtain a polyester having a high degree of polymerization. On the other hand, if it exceeds the upper limit, the decomposition amount of the aliphatic diol and aliphatic dicarboxylic acid increases, which is not preferable.

  In the present invention, the “molar ratio of the aliphatic diol component to the aliphatic dicarboxylic acid component for performing the esterification reaction” refers to the aliphatic dicarboxylic acid and esterification present in the gas phase and reaction liquid phase of the esterification reaction tank A. Represents the molar ratio of aliphatic diol and esterified aliphatic diol to the obtained aliphatic dicarboxylic acid, and decomposes in the reaction system and does not contribute to the esterification reaction, aliphatic dicarboxylic acid, aliphatic diol and their decomposition products Is not included. The fact that it is decomposed and does not contribute to the esterification reaction does not include, for example, those in which 1,4-butanediol, which is an aliphatic diol, is decomposed into tetrahydrofuran, in this molar ratio. In order to keep this molar ratio within a preferable range, it is preferable to appropriately supplement the esterification reaction system with an aliphatic diol. FIG. 1 shows a mode in which a BG supply line 3 is connected to a BG recirculation line 2 described later, and both are mixed and then supplied to the liquid phase part of the esterification reaction tank A.

  The lower limit of the esterification reaction temperature is usually 215 ° C or higher, preferably 218 ° C or higher, and the upper limit is usually 240 ° C or lower, preferably 235 ° C or lower, more preferably 233 ° C or lower. If the reaction temperature is lower than the lower limit, the esterification reaction rate becomes slow, requiring a long reaction time, and undesired reactions such as dehydration decomposition of aliphatic diols tend to occur. On the other hand, when the reaction temperature exceeds the upper limit, the aliphatic diol and the aliphatic dicarboxylic acid are decomposed more, and the amount of scattered matter increases in the reaction tank, which is likely to cause foreign matter. As a result, the reaction product becomes turbid (haze). ). The esterification reaction temperature is preferably a constant temperature in order to stabilize the esterification rate. The constant temperature refers to a range of ± 5 ° C. of the normal set temperature, and preferably within a range of ± 2 ° C.

  The reaction pressure is 50 kPa to 200 kPa, the lower limit is preferably 60 kPa, more preferably 70 kPa, and the upper limit is preferably 130 kPa, more preferably 110 kPa. When the reaction pressure is lower than the lower limit, the amount of scattered matter increases in the reaction tank and the haze of the reaction product increases, which tends to increase foreign matter. In addition, the distillation of the aliphatic diol to the outside of the reaction system increases and the polycondensation reaction rate tends to decrease. On the other hand, when the reaction pressure is higher than the upper limit, the dehydration decomposition of the aliphatic diol increases, and the polycondensation rate tends to decrease.

  The reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. Moreover, reaction time is 1 hour or more normally, and an upper limit is 10 hours or less normally, Preferably it is 4 hours or less.

  As the esterification reaction tank A used in the present invention, a known one can be used, and any of a vertical stirring complete mixing tank, a vertical heat convection mixing tank, a tower type continuous reaction tank and the like may be used. Among them, a reaction tank having a stirrer is preferable. As a stirrer, in addition to a normal type including a power unit and a bearing, a shaft, and a stirring blade, a turbine stator type high-speed rotating stirrer, a disk mill type stirrer, a rotor mill type stirrer, and the like The type that rotates at a high speed can also be used. In the illustrated embodiment, the esterification reaction is performed in one esterification reaction tank A. However, as shown in the figure, a single tank may be used, or a plurality of tanks of the same or different types may be connected in series.

  There is no limitation on the form of stirring, and in addition to the normal stirring method in which the reaction liquid in the reaction tank is directly stirred from the top, bottom, side, etc. of the reaction tank, a part of the reaction liquid is piped outside the reaction tank, etc. It is possible to take a method of circulating the reaction liquid by taking it out with a line mixer and the like. In addition, known types of stirring blades can be selected, and specific examples include propeller blades, screw blades, turbine blades, fan turbine blades, disk turbine blades, fiddler blades, full zone blades, Max blend blades, and the like.

  In the esterification reaction, the gas distilled from the esterification reaction tank A is separated into a high-boiling component and a low-boiling component in the rectifying column C via the distillation line 5. Usually, the main component of the high boiling component is 1,4-butanediol, and the main component of the low boiling component is water and tetrahydrofuran (may be referred to as THF).

  The high-boiling components separated in the rectification column C are extracted from the extraction line 6, and partly circulated from the BG recirculation line 2 to the esterification reaction tank A via the pump D, and partly circulated. It is returned to the rectifying column C from the line 7. The surplus is extracted from the extraction line 8 to the outside. On the other hand, the light boiling component separated in the rectifying column C is extracted from the gas extraction line 9, condensed in the condenser G, and temporarily stored in the tank F through the condensate line 10. A part of the light boiling components collected in the tank F is returned to the rectification column C via the extraction line 11, the pump E and the circulation line 12, and the remaining part is extracted outside via the extraction line 13. The condenser G is connected to an exhaust device (not shown) via a vent line 14. The esterification reaction product generated in the esterification reaction tank A is supplied to the first polycondensation reaction tank a through the extraction pump B and the extraction line 4 of the esterification reaction product.

  In the process shown in FIG. 1, the BG supply line 3 is connected to the BG recirculation line 2, but both may be independent. Moreover, the raw material supply line 1 may be connected to the liquid phase part of the esterification reaction tank A. In addition, when a catalyst is added to the esterification reaction product before polycondensation, it is adjusted to a predetermined concentration in a catalyst preparation tank (not shown), and then passed through a catalyst supply line L7 and a supply line L8 in FIG. To the extraction line 4 for the esterification reaction product shown in FIG.

In the present invention, the esterification reaction product obtained by making the esterification rate 80% or more in the esterification reaction step is subjected to the next polycondensation reaction. Here, the esterification rate indicates the ratio of the esterified acid component to the total acid component in the esterification reaction product sample, and is represented by the following formula.
Esterification rate (%) = (saponification value−acid value) / saponification value) × 100

  The esterification rate of the esterification reaction product is usually 80% or more, preferably 85% or more, more preferably 88% or more, and particularly preferably 90% or more. If the esterification rate is lower than the lower limit, the reactivity of the polycondensation reaction, which is a reaction in the subsequent step, becomes worse. In addition, scattered matter during the polycondensation reaction increases, adheres to the wall surface and solidifies, and further, the scattered matter falls into the reaction product, causing haze deterioration (foreign matter generation). The upper limit is preferably as high as possible for the polycondensation reaction, which is a post-process reaction, but is usually 99%.

  The terminal carboxyl group concentration of the esterification reaction product is preferably 500 to 2500 equivalent / ton. The lower limit is more preferably 600 equivalent / ton, and particularly preferably 700 equivalent / ton. The upper limit is more preferably 2000 equivalent / ton, and particularly preferably 1800 equivalent / ton. If it is lower than the lower limit, the decomposition of the aliphatic diol increases. In addition, scattered matter during the polycondensation reaction increases, adheres to the wall surface and solidifies, and further, the scattered matter falls into the reaction product, causing haze deterioration (foreign matter generation).

  The haze is reduced by conducting a continuous reaction with the molar ratio of dicarboxylic acid and diol in the esterification reaction, reaction temperature, reaction pressure and reaction rate within the above ranges and continuously subjecting the esterification reaction product to a polycondensation reaction. A high-quality aliphatic polyester with few foreign substances can be obtained efficiently.

  The esterification reaction product passed through the esterification reaction product extraction line 4 and the filter p is supplied to the first polycondensation reaction tank a shown in FIG. 2 and polycondensed under reduced pressure to become a polyester low polymer. The polyester low polymer polycondensed in the first polycondensation reaction tank a is then supplied to the second polycondensation reaction tank d via the extraction gear pump c, the extraction line L1, which is the outlet channel, and the filter q. The In the second polycondensation reaction tank d, the polycondensation reaction is usually further advanced at a lower pressure than the first polycondensation reaction tank a. The obtained polycondensate is supplied to the third polycondensation reaction tank k through the extraction gear pump e, the extraction line L3 serving as the outlet flow path, and the filter r, where the polycondensation reaction further proceeds.

  There is no restriction | limiting in particular in the type of the polycondensation reaction tank used for this invention, For example, a vertical stirring polymerization tank, a horizontal stirring polymerization tank, a thin film evaporation type polymerization tank etc. can be mentioned. The polycondensation reaction tank may be a single tank or a plurality of tanks in which a plurality of tanks of the same kind or different kinds are connected in series as shown in the figure. In the latter stage of the polycondensation in which the temperature rises, it is preferable to select a horizontal stirring polymerization machine having a thin film evaporation function excellent in interface renewability, plug flow property and self-cleaning property. For example, in the present embodiment, the third polycondensation reaction tank k is a horizontal reaction tank that includes a plurality of stirring blade blocks and includes a biaxial self-cleaning type stirring blade.

  The polycondensation reaction is usually performed under reduced pressure. The lower limit of the reaction pressure of the final polycondensation reaction tank is usually 0.01 kPa or more, preferably 0.03 kPa or more, and the upper limit is usually 1.4 kPa or less, preferably 0.4 kPa or less. If the pressure during the polycondensation reaction is too high, the polycondensation time will be prolonged, and accordingly, the molecular weight will be lowered or colored due to thermal decomposition of the polyester, which tends to make it difficult to produce a polyester exhibiting practically sufficient characteristics. On the other hand, the method of producing using an ultra-high vacuum polycondensation facility is a preferred embodiment from the viewpoint of improving the polycondensation reaction rate, but it is economically disadvantageous because it requires an extremely expensive equipment investment.

  The lower limit of the reaction temperature is usually 215 ° C or higher, preferably 220 ° C or higher, and the upper limit is usually 270 ° C or lower, preferably 260 ° C or lower. If this temperature is too low, the polycondensation reaction rate is slow, and not only does it take a long time to produce a polyester with a high degree of polymerization, but also a high power stirrer is required, which is economically disadvantageous. On the other hand, if the reaction temperature is too high, thermal decomposition of the polyester during production tends to be caused, and it tends to be difficult to produce polyester having a high degree of polymerization.

  The lower limit of the reaction time is usually 1 hour or longer, and the upper limit is usually 15 hours or shorter, preferably 8 hours or shorter, more preferably 6 hours or shorter. If the reaction time is too short, the reaction is insufficient and it is difficult to obtain a polyester having a high degree of polymerization, and the mechanical properties of the molded product tend to be inferior. On the other hand, if the reaction time is too long, the molecular weight drop due to the thermal decomposition of the polyester becomes remarkable, the mechanical properties of the molded product tend to be inferior, and the terminal amount of the carboxyl group that adversely affects the durability of the polyester is thermally decomposed. May increase due to

  The aliphatic polyester that has undergone the polycondensation reaction in the third polycondensation reaction tank k is extracted in the form of a melted strand from the die head g via the extraction gear pump m, the extraction line L5 that is the outlet channel, and the filter s. After being taken out and cooled with water or the like, it is cut with a rotary cutter h to form polyester pellets. L2, L4, and L6 are vent lines for the first polycondensation reaction tank a, the second polycondensation reaction tank d, and the third polycondensation reaction tank k, respectively.

  In FIG. 2, the filters p, q, r, and s installed before and after each polycondensation reaction tank are for removing foreign substances in the reaction product, and do not necessarily need to be installed at all. And can be installed as appropriate in consideration of operational stability.

(3) Aliphatic polyester The intrinsic viscosity ([η] dL / g) of the aliphatic polyester obtained by the production method of the present invention is preferably 1.3 dL / g or lower, particularly preferably 1 .6 dL / g or more. The upper limit is preferably 2.8 dL / g or less, more preferably 2.5 dL / g or less, and particularly preferably 2.3 dL / g or less. When the intrinsic viscosity is lower than the lower limit, it is difficult to obtain sufficient mechanical strength when formed into a molded product. On the other hand, if the intrinsic viscosity is higher than the upper limit, the melt viscosity is high at the time of molding and it is difficult to mold.

  The lower limit of the terminal carboxyl group concentration (equivalent / ton) of the aliphatic polyester is preferably 5 or more, more preferably 7 or more, still more preferably 10 or more, and particularly preferably 13 or more. The upper limit is preferably 30 or less, more preferably 25 or less, still more preferably 20 or less, and particularly preferably 18 or less. The lower the terminal carboxyl group concentration, the better the thermal stability and hydrolysis resistance. However, if the terminal carboxyl group concentration is too low, it is necessary to reduce the amount of catalyst or the polymerization temperature. This causes a decrease in the polycondensation reaction rate, which is practical. The molecular weight does not increase with speed. On the other hand, if it is too high, the thermal stability is poor and thermal decomposition increases during molding.

  Further, the color b value in the Hunter color coordinates of the aliphatic polyester pellets produced by the above production method preferably has a lower limit of −3.0 or more, more preferably −1.0 or more, and particularly preferably. Is 0.0 or more. The upper limit is preferably 3.0 or less, more preferably 2.5 or less, and particularly preferably 2.0 or less. If the color b value is too small, the molded product may be bluish and unfavorable, and if it is too large, the molded product may be yellowish and unfavorable.

The solution haze of the aliphatic polyester is preferably 0.01 to 2.5%. The lower the lower limit, the more transparent product may be obtained, but it is usually 0.01% or more. The upper limit is more preferably 2.0% or less, still more preferably 1.5% or less, and particularly preferably 1.0% or less. If the solution haze is too large, the molded product becomes turbid, and the amount of foreign matters increases, which is not preferable. Here, the solution haze refers to the turbidity at an optical path length of 10 mm of a solution having a sample concentration of 10% by mass using a mixed solution of phenol / tetrachloroethane = 3/2 (mass ratio) as a solvent, and is expressed in%.

  In particular, the intrinsic viscosity of the aliphatic polyester is 1.3 to 2.5 dL / g, the terminal carboxy group concentration is 5 to 30 equivalent / ton, the solution haze is 0.01 to 2.5%, and the color b value is If it is -3.0 to 3.0, it can be used as a raw material for a good polyester molded article with excellent balance of moldability, thermal stability and color tone. Further, since the polymer is highly transparent in the molten state at the time of production, it can be used for molded products such as high-quality films and sheets.

  The aliphatic polyester obtained by the production method of the present invention may be blended with an aromatic-aliphatic copolymer polyester, an aliphatic oxycarboxylic acid or the like to form an aliphatic polyester composition. In addition to carbodiimide compounds, fillers, and plasticizers used as necessary, other biodegradable resins, such as polycaprolactone, polyamide, polyvinyl alcohol, cellulose ester, etc., within a range that does not impair the effects of the present invention, An aliphatic polyester composition may be prepared by blending starch, cellulose, paper, wood powder, chitin / chitosan, animal / plant material fine powder such as coconut shell powder, walnut shell powder, or a mixture thereof. Furthermore, additives such as heat stabilizers, plasticizers, lubricants, antiblocking agents, nucleating agents, inorganic fillers, colorants, pigments, ultraviolet absorbers, light stabilizers, etc., are used for the purpose of adjusting the physical properties and processability of the molded product. Further, a modifier, a crosslinking agent, etc. may be included.

  The production method of the aliphatic polyester composition is not particularly limited, but is a method in which raw material chips of the blended aliphatic polyester are melt-mixed in the same extruder, a method in which each is melted in a separate extruder, and then mixed, a single screw extrusion Mixing by kneading using a conventional kneader such as a machine, a twin-screw extruder, a Banbury mixer, a roll mixer, a Brabender plastograph, a kneader blender, and the like. In addition, it is possible to obtain a molded body at the same time as preparing a composition by directly supplying each raw material chip to a molding machine.

  The aliphatic polyester obtained by the production method of the present invention and the resin composition using the aliphatic polyester have practical physical properties such as thermal stability, tensile strength, and tensile elongation. Therefore, the injection molding method, the hollow molding method, and the extrusion molding method are used. General-purpose plastic molding methods such as film, laminate film, sheet, plate, stretched sheet, monofilament, multifilament, non-woven fabric, flat yarn, staple, crimped fiber, striped tape, split yarn, composite fiber, blow bottle, It can be used for molded products such as foams.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example at all unless the summary is exceeded. In addition, the measuring method of the physical property and evaluation item which were employ | adopted in the following examples is as follows.

<Analysis of metal elements in catalyst>
A sample of 0.1 g of a sample obtained by wet decomposition with hydrogen peroxide in the presence of sulfuric acid in a Kjeldahl flask and then with a constant volume of distilled water was used. Plasma emission spectroscopic analyzer (ICP-AES ULTRACE JY-138U type manufactured by JOBIN YVON) ) And converted to the metal content (mass%) in the catalyst.

<PH analysis of catalyst solution>
Using an automatic titrator (AUT-301 type manufactured by Toa DKK), the pH electrode was immersed in a liquid catalyst and measured in the atmosphere.

<Terminal carboxyl group concentration of esterification reaction product equivalent / ton>
0.3 g of the esterification reaction product sample was put in 40 mL of benzyl alcohol, heated at 180 ° C. for 20 minutes, cooled for 10 minutes, and then titrated with a 0.1 mol·L− ¹ KOH / methanol solution. Expressed in tons.

<Esterification rate%>
It calculated from the acid value and the saponification value by the following calculation formula (1). The acid value is obtained by placing 0.3 g of the esterification reaction product sample in 40 mL of benzyl alcohol, heating at 180 ° C. for 20 minutes, cooling for 10 minutes, and titrating with a 0.1 mol·L− ¹ KOH / methanol solution. It was. The saponification value was determined by hydrolyzing the oligomer with a 0.5N KOH / ethanol solution and titrating with 0.5N hydrochloric acid.
Esterification rate = ((saponification value−acid value) / saponification value) × 100 (1)

<Intrinsic viscosity (IV) dL / g>
It calculated | required in the following way using the Ubbelohde type viscometer. That is, using a mixed solvent of phenol / tetrachloroethane (mass ratio 1/1) and measuring the number of seconds of dropping only the polymer solution having a concentration of 0.5 g / dL and the solvent at 30 ° C., the following formula (2) I asked more.
IV = ((1 + 4K _H η _SP ) ^0.5 −1) / (2K _H C) (2)
(Where η _SP = η / η ₀ −1, where η is the sample solution drop seconds, η ₀ is the solvent drop seconds, C is the sample solution concentration (g / dL), and K _H is the Huggins constant. there .K _H adopted the 0.33.)

<Polyester carboxyl group concentration (AV) equivalent / ton>
After pulverizing the pelletized polyester, it was dried with a hot air dryer and cooled to room temperature in a desiccator, 0.1 g was accurately weighed and collected in a test tube, 3 mL of benzyl alcohol was added, and dry nitrogen gas was added. Was dissolved at 195 ° C. for 3 minutes. Then, 5 cm ³ of chloroform was gradually added and cooled to room temperature. Add 1 to 2 drops of phenol red indicator to this solution and titrate with 0.1 mol·L ⁻¹ sodium benzyl alcohol solution with stirring while blowing dry nitrogen gas. Ended. Moreover, the same operation was implemented as a blank, without adding a polyester sample, and the amount of terminal carboxyl groups (acid value) was computed by the following formula | equation (3).
Terminal carboxyl content (equivalent / ton) = (ab) × 0.1 × f / W (3)

Here, a is the amount (μL) of 0.1 mol·L ⁻¹ sodium benzyl alcohol solution required for titration, and b is 0.1 mol·L ⁻¹ water required for titration with a blank. The amount (μL) of sodium oxide in benzyl alcohol, W is the amount (g) of polyester sample, and f is the titer of 0.1 mol·L ⁻¹ sodium hydroxide in benzyl alcohol.
The titer (f) of a benzyl alcohol solution of 0.1 mol·L ⁻¹ sodium hydroxide was determined by the following method. Collect 5 cm ³ of methanol in a test tube and add 1-2 drops as an indicator of phenol red in ethanol solution. Titration to a discoloration point was performed with 0.4 cm ³ of benzyl alcohol solution of ¹ mol·L ⁻¹ sodium hydroxide, and then 0.2 cm ³ of 0.1 mol·L ⁻¹ hydrochloric acid aqueous solution with known titer was taken as a standard solution. In addition, the solution was again titrated to a discoloration point with a benzyl alcohol solution of 0.1 mol·L ⁻¹ sodium hydroxide (the above operation was performed while blowing dry nitrogen gas). And titer (f) was computed by the following formula | equation (4).
The titer (f) = 0.1mol · ^L titer × amount of collected aqueous hydrochloric acid 0.1N aqueous hydrochloric acid ^-1 ([mu] L) of sodium hydroxide /0.1mol · ^{L -1} benzyl alcohol solution titration Amount (μL) (4)

<Color b value>
Reference Example 1 of JIS Z8730 using pelletized polyester filled in a cylindrical powder measurement cell having an inner diameter of 30 mm and a depth of 12 mm and using a colorimetric color difference meter Z300A (manufactured by Nippon Denshoku Industries Co., Ltd.) The b value by the color coordinate of Hunter's color difference formula in the Lab display system described in the above was obtained as a simple average value of four values measured by rotating the measurement cell by 90 degrees by the reflection method.

<Solution haze%>
2.70 g of a polyester sample was placed in 20 mL of a mixed solution of phenol / tetrachloroethane = 3/2 (mass ratio), dissolved in 110 ° C. for 30 minutes, and then cooled in a constant temperature water bath at 30 ° C. for 15 minutes. Using a turbidimeter (NDH-300A manufactured by Nippon Denshoku Co., Ltd.), the turbidity of the solution was measured with a cell having an optical path length of 10 mm to obtain a solution haze. It shows that transparency is so favorable that a value is low.

<THF conversion mol%>
The amount of 1,4-butanediol decomposed into THF during the esterification reaction was charged and expressed as mol% with respect to the amount of succinic acid. Specifically, in the case of continuous reaction (from Example 1 to Comparative Example 2), the distillate mass and the distillate from the extraction line (13) in FIG. 1 from the 16th to the 24th hour after the start of the reaction. After calculating the distilled THF mass per unit time from the THF concentration (mass%) in the liquid, it was obtained from the following formula (5).
THF conversion rate (mol%) = (mass of distilled THF per unit time / 72.11) / (mass succinic acid supplied to the esterification reactor per unit time / 118.09) × 100 (5) )
The THF concentration (mass%) in the distillate was determined by the following method. That is, about 1 g of the distillate was precisely weighed, 5 ml of a dioxane solution of n-dodecane (0.025 g of n-dodecane / 5 ml of dioxane) was added, and the amount was obtained from the following formula (6) by gas chromatography. Moreover, the correction coefficient was calculated | required from the effective carbon number on the basis of the dioxane, and THF used 1.640.
THF concentration (% by mass) in the distillate = (THF peak area × correction coefficient / n-dodecane peak area × 0.025) / distillate precise balance (6)
The apparatus is GC-14BPF (manufactured by Shimadzu Corporation) (split ratio: 1/90, RANGE: 10 ¹ ), and the column is DB-WAX (inner diameter: 0.32 mm, length: 60 m, membrane pressure) manufactured by J & W. : 0.5 μm). The temperature of the injection section and detector was 240 ° C., the column temperature was raised from 90 ° C. to 230 ° C. at 7 ° C./min, and then maintained at 230 ° C. for 20 minutes. Nitrogen (1 mL / min) was used as the carrier gas.
The THF conversion rate in the batch reaction (Comparative Example 3) is calculated after calculating the THF mass from the mass of the distillate distilled during the ester reaction in the esterification reaction tank and the THF concentration (mass%) in the distillate. It calculated | required from the following formula | equation (7).
THF conversion rate (mol%) = (mass of distilled THF during esterification reaction / 72.11) / (mass succinic acid charged into esterification reaction tank / 118.09) × 100 (7)

Example 1
[Preparation of catalyst for polycondensation]
Into a glass eggplant-shaped flask equipped with a stirrer, 100 parts by mass of magnesium acetate tetrahydrate was added, and 1500 parts by mass of absolute ethanol (purity 99% by mass or more) was further added. Further, 130.8 parts by mass of ethyl acid phosphate (mixing mass ratio of monoester and diester was 45:55) was added, and the mixture was stirred at 23 ° C. After confirming that magnesium acetate was completely dissolved after 15 minutes, 529.5 parts by mass of tetra-n-butyl titanate was added. Stirring was further continued for 10 minutes to obtain a uniform mixed solution. This mixed solution was transferred to an eggplant-shaped flask and concentrated under reduced pressure by an evaporator in an oil bath at 60 ° C. After 1 hour, most of ethanol was distilled off to obtain a translucent viscous liquid. The temperature of the oil bath was further raised to 80 ° C., and further concentrated under a reduced pressure of 5 Torr to obtain a viscous liquid. This liquid catalyst was dissolved in 1,4-butanediol to prepare a titanium atom content of 3.36% by mass. The storage stability of this catalyst solution in 1,4-butanediol was good, and no precipitate was observed in the catalyst solution stored at 40 ° C. in a nitrogen atmosphere for at least 40 days. The catalyst solution had a pH of 6.3.

[Production of aliphatic polyester]
By the esterification process shown in FIG. 1 and the polycondensation process shown in FIGS. 2 and 3, an aliphatic polyester resin was produced in the following manner. First, with respect to 1.00 mol of succinic acid containing 0.18% by mass of malic acid, 1.30 mol of 1,4-butanediol and malic acid were mixed at a total amount of 0.0033 mol. A 50 ° C. slurry was charged in advance from a slurry preparation tank (not shown) through a raw material supply line (1) with an aliphatic polyester low molecular weight substance (esterification reaction product) having an esterification rate of 99 mass% in a nitrogen atmosphere. It supplied continuously to the esterification reaction tank (A) which has a stirrer so that it might become 45.5 kg / h.

  The internal temperature of the esterification reaction tank (A) is 230 ° C., the pressure is 101 kPa, and the produced water, tetrahydrofuran and excess 1,4-butanediol are distilled from the distillation line (5), and a rectifying column ( In C), a high boiling component and a low boiling component were separated. A part of the high-boiling component at the bottom of the column after the system was stabilized was extracted to the outside through an extraction line (8) so that the liquid level of the rectification column (C) was constant. On the other hand, a low boiling component mainly composed of water and THF is extracted in the form of gas from the top of the column, condensed by a condenser (G), and an extraction line (13) so that the liquid level of the tank (F) becomes constant. More extracted outside. At the same time, the total amount of the bottom component (98% by mass or more of 1,4-butanediol) of the rectification column (C) at 100 ° C. from the BG recirculation line (2) and the ester from the BG supply line (3) Tetrahydrofuran generated in the oxidization reaction tank and equimolar 1,4-butanediol are supplied together, and the molar ratio of 1,4-butanediol to succinic acid in the esterification reaction tank is adjusted to 1.30. did. The supply amount of the recirculation line (2) and the BG supply line (3) was 3.8 kg / h. The amount of 1,4-butanediol converted to tetrahydrofuran was 0.042 mol (THF conversion rate: 4.2 mol% to succinic acid) with respect to 1.00 mol of succinic acid.

  The esterification reaction product produced in the esterification reaction tank (A) is continuously extracted from the extraction line (4) of the esterification reaction product using the extraction pump (B), and the esterification reaction tank (A). The liquid level was controlled such that the average residence time of the internal liquid in terms of succinic acid unit was 3 hours. The esterification reaction product extracted from the extraction line (4) was continuously supplied to the first polycondensation reaction tank (a). After the system was stabilized, the esterification rate of the esterification reaction product collected at the outlet of the esterification reaction tank (A) was 92.4%, and the terminal carboxyl concentration was 884 equivalent / ton.

  After preparing a catalyst solution prepared in advance by the above-described method with a catalyst preparation tank diluted with 1,4-butanediol so that the concentration as titanium atoms is 0.12% by mass in a catalyst preparation tank, a catalyst supply line ( L7) and the supply line (L8) were continuously supplied to the esterification reaction product extraction line (4) at 1.4 kg / h (the catalyst was added to the liquid phase of the reaction solution). The supply was stable during the operation period.

  The liquid level was controlled so that the internal temperature of the first polycondensation reaction tank (a) was 240 ° C., the pressure was 2.67 kPa, and the residence time was 120 minutes. An initial polycondensation reaction was performed while extracting water, tetrahydrofuran, and 1,4-butanediol from a vent line (L2) connected to a decompressor (not shown). The extracted reaction liquid was continuously supplied to the second polycondensation reactor (d).

  Vent connected to a decompressor (not shown) with the internal temperature of the second polycondensation reaction tank (d) being 240 ° C., the pressure being 0.67 kPa, the liquid level being controlled so that the residence time is 90 minutes. The polycondensation reaction was further advanced while extracting water, tetrahydrofuran and 1,4-butanediol from the line (L4). The obtained polyester was continuously supplied to the third polycondensation reactor (k) via the extraction line (L3) by the extraction gear pump (e). The internal temperature of the third polycondensation reactor (k) was 240 ° C., the pressure was 130 Pa, the residence time was 60 minutes, and the polycondensation reaction was further advanced. The obtained polyester was continuously extracted in the form of a strand from the die head (g) and cut with a rotary cutter (h) to obtain pellets. The esterification reaction and polycondensation reaction were carried out for 7 consecutive days, and the physical properties of the aliphatic polyester obtained by sampling every 8 hours after the lapse of 16 hours from the start of the reaction were measured. As a result obtained in Table 1, the average value and the touch width of each sample are shown.

(Example 2)
A polyester was obtained in the same manner as in Example 1 except that the internal temperature of the esterification reaction tank (A) was 220 ° C. Table 1 shows the measurement results of the sample 24 hours after the start of the reaction.

(Example 3)
The pressure of the esterification reactor (A) is 66.7 kPa, and the BG supply line (3) and the recirculation line (so that the molar ratio of 1,4-butanediol to succinic acid in the esterification reactor is 1.50) A polyester was obtained in the same manner as in Example 1 except that the flow rate of 2) was adjusted. Table 1 shows the measurement results of the sample 24 hours after the start of the reaction.

Example 4
In the esterification reactor (A), the flow rates of the BG supply line (3) and the recirculation line (2) are adjusted so that the molar ratio of 1,4-butanediol to succinic acid in the esterification reactor is 1.50. A polyester was obtained in the same manner as in Example 1 except for the adjustment. Table 1 shows the measurement results of the sample 24 hours after the start of the reaction.

(Example 5)
50 ° C. in which 1,4-butanediol was mixed to 1.10 mol and malic acid was mixed to a total amount of 0.0033 mol with respect to 1.00 mol of succinic acid containing 0.13% by mass of malic acid. Was continuously fed to the esterification reaction tank (A) so as to be 42.0 kg / h. In the esterification reactor (A), the flow rates of the BG supply line (3) and the recirculation line (2) are adjusted so that the molar ratio of 1,4-butanediol to succinic acid in the esterification reactor is 1.10. A polyester was obtained in the same manner as in Example 1 except for the adjustment. Table 1 shows the measurement results of the sample 24 hours after the start of the reaction.

(Example 6)
The BG supply line (3) and the recirculation line (in order that the internal temperature of the esterification reactor (A) is 220 ° C. and the molar ratio of 1,4-butanediol to succinic acid in the esterification reactor is 1.80. A polyester was obtained in the same manner as in Example 1 except that the flow rate of 2) was adjusted. Table 1 shows the measurement results of the sample 24 hours after the start of the reaction.

(Example 7)
The catalyst solution prepared in advance by the “preparation of polycondensation catalyst” method of Example 1 was added with 1,4-butanediol in a catalyst preparation tank so that the concentration as titanium atoms was 0.12% by mass. After the diluted catalyst solution was prepared, it was continuously supplied to the esterification reaction tank (A) at 0.56 kg / h through the catalyst supply line (15). A catalyst solution having a concentration of 0.12% by mass was supplied through the catalyst supply line (L7) and the supply line (L8) to the extraction line (4) for the esterification reaction product at 0.83 kg / h. The polymer was obtained in the same manner as in Example 1. The results are shown in Table 1. The measurement results of the sample 24 hours after the start of the reaction are shown in Table 1.

(Example 8)
In the gas phase part of the first polycondensation reaction tank (a), the catalyst solution prepared in advance by the “preparation of catalyst for polycondensation” method of Example 1 has a concentration as titanium atoms of 0.12% by mass. Thus, polyester was obtained in the same manner as in Example 1 except that the catalyst solution diluted with 1,4-butanediol was continuously supplied at 1.4 kg / h through the supply line (16). Table 1 shows the measurement results of the sample 24 hours after the start.

(Comparative Example 1)
A 60 ° C. slurry in which 1,4-butanediol was mixed at a ratio of 1.16 mol with respect to 1.00 mol of succinic acid was converted into an esterification reaction vessel (A ) Continuously. The BG supply line (in which the internal temperature of the esterification reactor (A) is 210 ° C., the average residence time is 1 hour, and the 1,4-butanediol molar ratio to succinic acid in the esterification reactor is 1.16. A polyester was obtained in the same manner as in Example 1 except that the flow rates of 3) and the recirculation line (2) were adjusted. Table 1 shows the measurement results of the sample 24 hours after the start of the reaction.

(Comparative Example 2)
A 60 ° C. slurry in which 1,4-butanediol was mixed at a ratio of 1.16 mol with respect to 1.00 mol of succinic acid was converted into an esterification reaction vessel (A ) Continuously. In addition, as a catalyst, a 90% aqueous lactic acid solution adjusted to a germanium dioxide concentration of 1% by mass was supplied to the esterification reaction tank (A) to a supply line (15) so as to be 1.2 kg / h. Through the continuous supply. Furthermore, as an adjustment of the 1,4-butanediol molar ratio to succinic acid in the esterification reaction tank, a polyester was obtained in the same manner as in Example 1 except that 1,4-butanediol was not supplied. The molar ratio of 1,4-butanediol to succinic acid in the esterification reactor was 1.09. Table 1 shows the measurement results of the sample 24 hours after the start of the reaction.

(Comparative Example 3)
100 parts by mass of succinic acid containing 0.14% by mass of malic acid in succinic acid as a raw material in a reaction vessel equipped with a stirrer, a nitrogen inlet, a heating device, a thermometer and a vacuum outlet, 1,4- 99.2 parts by mass of butanediol and 0.24 parts by mass of malic acid (total malic acid amount 0.33 mol% with respect to succinic acid) were charged, and the system was placed in a nitrogen atmosphere by nitrogen-reduced pressure substitution.

Next, the temperature was raised while stirring the system, and the esterification was completed when the internal temperature reached 230 ° C. (130 minutes). Thereafter, a catalyst solution prepared by diluting the catalyst solution prepared by the “preparation of polycondensation catalyst” method of Example 1 with 1,4-butanediol so that the concentration as a titanium atom becomes 1.0 mass% is prepared. The amount added was 50 ppm as titanium atoms per polyester obtained, the temperature was raised to 240 ° C. over 30 minutes, and the pressure was reduced to 0.06 × 10 ³ Pa over 1 hour 30 minutes. The polyester was further reacted for 8.1 hours under a reduced pressure of 0.06 × 10 ³ Pa. The results are shown in Table 1.

  From Table 1, the polyester (Example 1-Example 8) manufactured with the manufacturing method of this invention had the result of all the quality tests favorable. However, in Example 7 where the reaction was performed by adding a catalyst during the esterification reaction and in Example 8 where the catalyst was added to the gas phase during the polycondensation, a slight increase in solution haze was observed. Moreover, since the fluctuation width of the polyester physical property value measured at regular intervals in Example 1 is small, it can be seen that the polyester obtained by the production method of the present invention has a stable quality.

  On the other hand, the polyester obtained in Comparative Example 1 in which the reaction temperature of the esterification reaction is low and the esterification rate is low, and in Comparative Example 2 in which the molar ratio of the aliphatic diol component to the aliphatic dicarboxylic acid component is small, particularly the terminal carboxyl group concentration And in terms of solution haze. Further, the polyester of Comparative Example 3 produced by the batch method had a high terminal carboxyl group concentration and a high quality touch range.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. The present invention can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and a manufacturing method involving such a change is also understood to be included in the technical scope of the present invention. It must be.

1: Raw material supply line 2: BG recirculation line 3: BG supply line 4: Extraction line for esterification reaction product 5: Distillation line 6: Extraction line 7: Circulation line 8: Extraction line 9: Gas extraction Line 10: Condensate line 11: Extraction line 12: Circulation line 13: Extraction line 14: Vent line 15, 16: Catalyst supply line A: Esterification reaction tank B: Extraction pump C: Rectification tower D, E : Pump F: tank G: condensers L1, L3, L5: polycondensation reaction product extraction lines L2, L4, L6: vent line L7: catalyst supply line L8: supply line a: first polycondensation reaction tank d: second Polycondensation reaction tank k: Third polycondensation reaction tank c, e, m: Extraction gear pump g: Die head h: Rotary cutter p, q, r, s: Filter

Claims (1)

Intrinsic viscosity ([η] dL / g) is 1.3 to 2.5, terminal carboxyl group concentration (equivalent / ton) is 5 to 30, solution haze (%) is 0.01 to 2.50, color b value Is an aliphatic polyester having a viscosity of -3.0 to 3.0.

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