Method for producing polyester resin composition

Abstract

To provide a method for producing a polyester resin composition in which a distillate during a polycondensation reaction can be recovered and reused with high efficiency and at low cost and further a foreign matter derived from a catalyst can be reduced.SOLUTION: There is provided a method for producing a polyester resin composition by conducting an esterification reaction with a dicarboxylic acid component and a diol component or an ester exchange reaction with a dicarboxylic acid ester-forming derivative component and a diol component, followed by a polycondensation reaction, wherein the distillate during the polycondensation reaction is recovered and used as a solution satisfying the following expressions (i) and (ii) in one of the above reactions. Turbidity≤100 NTU (i), Germanium element (atom) content≤600 ppm (Weight ratio to solution) (ii).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a polyester resin composition. [Background technology]

[0002] Polyesters, for example, polyethylene terephthalate, are produced by polycondensation of polyester low polymers produced by esterification reaction of terephthalic acid and ethylene glycol or transesterification reaction of dimethyl terephthalate and ethylene glycol in the presence of a polycondensation catalyst. Here, in order to improve reactivity, ethylene glycol is supplied in excess of terephthalic acid or dimethyl terephthalate, and most of the catalysts and additives added in each reaction use ethylene glycol as a solvent, so that an excess of ethylene glycol exists in the polycondensation reaction compared to the theoretical amount of ethylene glycol contained in the polyester. As a result, it is necessary to distill off the excess ethylene glycol during the polycondensation reaction, and this ethylene glycol contains water, polyester decomposition products that are accompanied by azeotropy and scattering, and low polymers. The distilled ethylene glycol thus produced is purified into high-purity ethylene glycol in a polyester production process that includes a recovery process, and the high-purity ethylene glycol purified here is generally reused as a raw material. However, the recovery rate is not 100%, and the total amount of ethylene glycol used is large, which is one of the causes of cost increase. In addition, the substances removed in the process of recovering the distilled ethylene glycol are mainly low-boiling components such as water, polyester low polymers, catalysts and additives, and disposing of these substances increases the amount of raw materials, catalysts and additives used, which is a major cause of increased costs. In particular, when germanium dioxide is used as a polycondensation catalyst, about half of the amount added is distilled off together with ethylene glycol during the polycondensation reaction, which increases the amount of germanium dioxide added, resulting in an issue of increased polyester production costs.

[0003] In response to these issues, studies have been carried out as shown in the following documents. Patent Documents 1 and 2 disclose methods for directly reusing the distilled ethylene glycol as a raw material.

[0004] Patent Document 3 discloses a method for distilling and reusing germanium dioxide distilled off during a polycondensation reaction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 53-126096 [Patent Document 2] Patent Publication No. 55-110120 [Patent Document 3] Patent Publication No. 11-147946 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Documents 1 and 2 disclose a method of directly reusing the distilled ethylene glycol as a raw material. However, although this method alone can solve the above-mentioned cost problem, there is a concern that polyester decomposition products and low polymers in the distilled ethylene glycol may become foreign matter in the esterification reaction, the ester exchange reaction, and the polycondensation reaction, leading to deterioration of the polymer quality.

[0007] Patent Document 3 discloses a method of distilling and reusing germanium dioxide distilled during a polycondensation reaction. However, distillation increases the concentration of polyester decomposition products and low polymers in the distillate, and the fluidity of the concentrated liquid decreases, making transportation and mixing difficult. In addition, the saturated catalyst components are precipitated and turned into foreign matter due to the increase in the concentration of the catalyst components, which leads to a deterioration in polymer quality. In addition, dedicated equipment is required for distillation, which is an issue in terms of production costs.

[0008] An object of the present invention is to provide a method for producing a polyester resin composition which enables highly efficient and low-cost recovery and reuse of a distillate from a polycondensation reaction and reduces the amount of foreign matter derived from the catalyst. [Means for solving the problem]

[0009] As a result of intensive research aimed at solving the above problems, the inventors have arrived at a method for producing a polyester resin composition in which a distillate from a polycondensation reaction is recovered and utilized in either an esterification reaction, an ester exchange reaction, or a polycondensation reaction.

[0010] The object of the present invention is achieved by the following means. (1) A method for producing a polyester resin composition, which comprises carrying out an esterification reaction (A) between a dicarboxylic acid component and a diol component, or an ester exchange reaction (B) between a dicarboxylic acid ester-forming derivative component and a diol component, and then carrying out a polycondensation reaction (C), and recovering a distillate from the polycondensation reaction, and using the distillate as a solution that satisfies the following formulas (i) and (ii) in any of the above reactions (A) to (C). Turbidity ≦100NTU (i) Germanium element (atomic) content ≦ 600 ppm (weight ratio to the solution) (ii) (2) The method for producing a polyester resin composition according to (1), wherein the solution is obtained by cooling and / or filtering a distillate. (3) The method for producing a polyester resin composition according to (2), wherein the cooling temperature is less than 15°C. (4) The method for producing a polyester resin composition according to (2), wherein the filtration is carried out in two or more stages. (5) The method for producing a polyester resin composition according to (1), wherein the polyester is polyethylene terephthalate. (6) An apparatus for producing a polyester resin composition, comprising: a step of carrying out an esterification reaction (A) between a dicarboxylic acid component and a diol component, or a transesterification reaction (B) between a dicarboxylic acid ester-forming derivative component and a diol component; a step of carrying out a subsequent polycondensation reaction (C); a step of recovering a distillate from the polycondensation reaction; a step of purifying the distillate to obtain a solution; and a step of sending the obtained solution that satisfies the following formulas (iii) and (iv) to any one of the above reaction steps. Turbidity≦100NTU (iii) Germanium element (atomic) content ≦ 600 ppm (weight ratio to the solution) (iv) Effect of the Invention

[0011] The present invention provides a method for producing a polyester resin composition which enables highly efficient and low-cost recovery and reuse of a distillate from a polycondensation reaction and reduces foreign matter derived from the catalyst. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in detail below. The polyester resin composition of the present invention refers to a polyester resin obtained by polycondensation of a dicarboxylic acid component or its ester with a diol component. The method for producing this polyester resin composition uses a dicarboxylic acid component or its ester and a diol component as main raw materials and consists of the following two-stage process. That is, the first stage is (A) an esterification reaction or (B) an ester exchange reaction, and the second stage is (C) a polycondensation reaction.

[0013] The raw materials used in the method for producing the polyester resin composition of the present invention may be a dicarboxylic acid or a dicarboxylic acid ester and a diol, and it is also possible to use two or more kinds in combination.

[0014] Examples of the dicarboxylic acid used in the present invention include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenyl-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, malonic acid, and dimer acid. The dicarboxylic acid ester is a lower alkyl ester, an acid anhydride, or an acyl chloride of the above-mentioned dicarboxylic acid, and preferably uses a methyl ester, an ethyl ester, or a hydroxyethyl ester. The more preferred embodiment of the dicarboxylic acid or dicarboxylic acid ester of the present invention is terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, or an alkyl ester thereof, in that a polyester resin composition that can be easily processed into a molded product can be obtained.

[0015] Examples of the diols used in the present invention include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, and neopentyl glycol; examples of the alicyclic diols include saturated alicyclic primary diols such as cyclohexanedimethanol, cyclohexanediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecane dimethanol, tricyclodecane diethanol, decalin dimethanol, and decalin diethanol; saturated heterocyclic primary diols containing cyclic ethers such as isosorbide; and other cyclohexyl ethers. Examples of the diol include various alicyclic diols such as Sandiol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, and adamantanediol, and aromatic diols such as paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, and 9,9'-bis(4-hydroxyphenyl)fluorene. In addition to the diols, polyfunctional alcohols such as trimethylolpropane and pentaerythritol can also be used within the scope of the present invention, so long as the effects of the present invention are not impaired. Ethylene glycol is preferred in that it can fully achieve the effects of the present invention.

[0016] In the manufacturing method of the present invention, the (A) esterification reaction step in the first step is a step in which a dicarboxylic acid and a diol are esterified at a predetermined temperature until a predetermined amount of water is distilled off to obtain a low polymer. When obtaining a low polymer by esterification, the molar ratio of dicarboxylic acid to diol (diol / dicarboxylic acid) before the start of the esterification reaction is preferably in the range of 1.05 to 1.40 in terms of esterification reactivity and heat resistance. More preferably, it is in the range of 1.05 to 1.30, and even more preferably, it is in the range of 1.05 to 1.20. By setting it in the above range, it has good reactivity and can suppress the generation of by-products such as dimers of diol, so that the heat resistance can be improved.

[0017] The (B) transesterification step is a step of transesterifying a dicarboxylic acid alkyl ester with a diol until a predetermined amount of alcohol is distilled to obtain a low polymer. When a low polymer is obtained by transesterification, the molar ratio of the dicarboxylic acid alkyl ester to the diol (diol / dicarboxylic acid alkyl ester) is preferably in the range of 1.7 to 2.3 from the viewpoints of reactivity and heat resistance. By setting the ratio in the above range, the transesterification reaction can be efficiently progressed and the by-production of a dimer of the diol can be suppressed, thereby improving the heat resistance.

[0018] Among the processes in the second stage, the (C) polycondensation reaction is a process for obtaining a polyester resin composition from a low polymer obtained by the (A) esterification reaction or the (B) transesterification reaction. The catalyst used in the polycondensation reaction can be a known polymerization catalyst or cocatalyst. For example, the polymerization catalyst can be an antimony compound, a titanium compound, a germanium compound, or an aluminum compound, but is not limited thereto. It is preferable to use a germanium compound from the viewpoint of transparency of the obtained polyester resin composition and suppression of foreign matter formation. In addition, since about half of the amount of the germanium compound added is distilled during the polycondensation reaction, it is also possible to reduce production costs by reusing the distillate.

[0019] The polycondensation reaction is carried out by gradually increasing the temperature and vacuum in the range of 200-300°C and 0.05-30 kPa to synthesize a polyester polymer, and the diol component generated by this polycondensation reaction is condensed in a condenser and recovered as a distillate. In the method for producing a polyester resin composition of the present invention, the recovered distillate is used in any one of the above reactions (A) to (C) as a solution satisfying the following formulas (i) and (ii). Turbidity ≦100NTU (i) Germanium element (atomic) content ≦ 600 ppm (weight ratio to the solution) (ii) (2) The method for producing a polyester resin composition according to (1), wherein the solution is obtained by cooling and / or filtering a distillate. In other words, the solution must be used as a raw material, catalyst, or additive in either (A) esterification reaction or (B) transesterification reaction, followed by (C) polycondensation reaction. The ratio of the distillate and new raw materials and additives used in this case can be adjusted without restrictions according to the desired quality of the resulting polyester resin composition, and can also be used repeatedly. When adding to the polycondensation reaction of (C), adding before the end of the polycondensation reaction can reduce the amount of catalyst to be added, which is advantageous in terms of cost when producing polyester.

[0020] When the distillate is used, the germanium element (atom) content must be 600 ppm or less based on the weight of the solution. When a germanium compound is selected as the polycondensation catalyst, the germanium compound scattered during the polycondensation reaction is taken into the distillate. If the germanium concentration in the distillate becomes high, precipitation occurs, which causes foreign matter when reused and causes deterioration of the polymer quality. The germanium element (atom) content is preferably 500 ppm or less, more preferably 400 ppm or less.

[0021] In addition, when the distillate is used, the turbidity of the solution must be 100 NTU or less. Turbidity is specified in the Japanese Industrial Standard JIS K 0101. The turbidity of a solution containing 1 mg / L of formazin, which is a standard substance, is expressed as 1 NTU, and the turbidity of the solution in the present invention is the scattered light turbidity, and the unit is defined as "NTU". The turbidity of the solution is preferably 80 NTU or less, and more preferably 60 NTU or less. Since the turbidity of the solution is related to the remaining amount of insoluble matter, if a solution with a turbidity of more than 100 NTU is reused, the haze of the polymer increases, the heat resistance deteriorates, and foreign matter increases in the polymer, leading to deterioration of the polymer quality.

[0022] Since the distillate is generated during the polycondensation reaction, the distillate obtained may be at a high temperature. When the distillate is at a high temperature, polyester decomposition products and low polymers that have been scattered and entrained are dissolved in the distillate, which causes deterioration of the polymer quality, such as an increase in haze, deterioration of heat resistance, and further formation of foreign matter, when the distillate is reused. Therefore, it is preferable that the distillate is sufficiently cooled. There is no limitation on the cooling method, but the cooling temperature is preferably less than 15°C, and more preferably less than 10°C. By setting the temperature to less than 10°C, the residual components in the distillate are sufficiently precipitated, making it possible to increase the purity of the distillate.

[0023] As described above, polyester decomposition products and low polymers scattered and entrained in the distillate cause deterioration of polymer quality and formation of foreign matter, and therefore are preferably removed by filtration. Examples of filtration methods include, but are not limited to, gravity filtration, vacuum filtration, and pressure filtration. In addition, in order to remove insoluble matter from the distillate with high precision, it is preferable to perform filtration in two or more stages, and by gradually reducing the filter size of the filtration, it is possible to efficiently remove insoluble matter without causing problems such as clogging.

[0024] Furthermore, the distillate may be subjected to treatments such as concentration, separation, and recrystallization within the scope of the invention.

[0025] The production method of the present invention can be applied to batch polymerization, semi-continuous polymerization, and continuous polymerization. In the method for producing the polyester composition of the present invention, the catalyst used in the esterification reaction (A) may be a compound such as manganese, cobalt, zinc, titanium, or calcium. In addition, the catalyst used in the transesterification reaction (B) may be a known transesterification catalyst. Examples of the transesterification catalyst include organic manganese compounds, organic magnesium compounds, organic calcium compounds, organic cobalt compounds, and organic lithium compounds, and specific examples thereof include carbonates, acetates, benzoates, oxides, and hydroxides, but are not limited thereto.

[0026] In addition, the catalyst used in the polycondensation reaction (C) can be a known polycondensation catalyst. Examples of such catalysts include compounds of antimony, titanium, aluminum, tin, and germanium. In addition, known additives can be used to obtain a polyester resin composition with desired physical properties, and examples of such additives include, but are not limited to, manganese compounds, magnesium compounds, calcium compounds, cobalt compounds, lithium compounds, and phosphorus compounds. From the viewpoint of improving the heat resistance of the polyester resin composition, it is preferable to add compounds containing phosphoric acid, lithium, sodium, and potassium phosphates, hydroxides, acetates, carbonates, nitrates, and chlorides, and multiple phosphorus compounds may be used in combination.

[0027] In the method for producing a polyester resin composition of the present invention, when the method is carried out via an esterification reaction (A), it is preferable to add a glycol component such as ethylene glycol after the esterification reaction and before the polycondensation reaction (C). The low molecular weight polyester composition obtained by the esterification reaction has a higher degree of polymerization than the low molecular weight polyester composition obtained by the transesterification reaction, and therefore compounds such as metal phosphates are difficult to disperse, and are prone to becoming foreign matter. Therefore, by adding a glycol component such as ethylene glycol and lowering the degree of polymerization by depolymerization, it is possible to suppress the formation of foreign matter.

[0028] The amount of the glycol component such as ethylene glycol to be added is preferably 0.05 to 0.5 times by mol relative to the total amount of the acid components constituting the polyester resin composition. By setting the amount within the above range, it is possible to prevent the metal phosphate from becoming a foreign substance without causing a delay in polymerization time due to a drop in temperature in the polymerization system.

[0029] Specific examples of the method for producing the polyester resin composition of the present invention will be given below, but the present invention is not limited thereto.

[0030] A slurry of terephthalic acid and ethylene glycol (1.15 times the molar amount of terephthalic acid) is gradually added to an esterification reactor containing dissolved bishydroxyethyl terephthalate at 250°C to allow the esterification reaction to proceed. The temperature in the reaction system is controlled to be 245-250°C, and the esterification reaction is terminated when the reaction rate reaches 95%.

[0031] The esterification product thus obtained at 255°C is transferred to a polymerization apparatus, and a manganese compound and a germanium compound are added. Then, ethylene glycol is added, and phosphoric acid and a sodium phosphate are added. During these operations, it is preferable to keep the temperature in the system at 240 to 255°C so that the esterification product does not solidify.

[0032] Then, while gradually increasing the temperature in the polymerization apparatus to 290°C, the pressure in the polymerization apparatus is gradually reduced from normal pressure to 133 Pa or less to distill off ethylene glycol. The reaction is terminated when a predetermined stirring torque is reached, the reaction system is brought to normal pressure with nitrogen gas, and the molten polyester is discharged into cold water in the form of strands and cut to obtain a polyester resin composition. The distillate generated is collected and sufficiently cooled in a cooling tank maintained at 5°C. The distillate is then filtered using a filter with a filtration accuracy of 4 μm, and the obtained filtrate is further filtered using a filter with a filtration accuracy of 0.5 μm. The solution thus obtained is used as a part of the raw material ethylene glycol in the above-mentioned esterification reactor.

[0033] The polyester resin composition obtained by the production method of the present invention has excellent heat resistance and transparency, and generates little catalyst-derived foreign matter, and can therefore be suitably used for various applications such as films, fibers, bottles, and injection molded products, and can be particularly used for high-quality films such as optical films and release films. EXAMPLES

[0034] The present invention will be described in more detail below with reference to examples. The physical properties in the examples were measured by the following methods.

[0035] (1) Germanium element (atom) content in the solution or polyester resin composition (unit: mass ppm) The solution was weighed out, decomposed by heating with sulfuric acid, nitric acid, perchloric acid and hydrofluoric acid, and then dissolved in dilute nitric acid to a constant volume. For the polyester resin composition, a sample was weighed out, decomposed by heating with sulfuric acid and nitric acid, and then dissolved in dilute nitric acid to a constant volume. The germanium element (atom) content in the sample was determined by ICP emission spectroscopy.

[0036] The ICP optical emission spectrometer used was the "PS3520VDDII" manufactured by Hitachi High-Tech Science Corporation.

[0037] (2) Turbidity of the solution (unit: NTU) The turbidity of the solution was measured using a HACH 2100N indoor high-performance turbidimeter. 100 mL of the solution at 20°C was shaken until homogenous, and then dispensed. The average value was measured three times. The turbidimeter was calibrated using formazin standard solution, and the turbidimeter turbidity was detected from the 90° scattered light.

[0038] (3) Intrinsic Viscosity IV of Polyester Resin Composition (Unit: dl / g) 0.1 g of the polyester resin composition was weighed out to within 0.001 g accuracy and dissolved in 10 ml of o-chlorophenol (hereinafter referred to as OCP) by heating at 100° C. for 30 minutes. The solution was cooled to room temperature, and 8 ml of the solution was placed in an Ostwald viscometer placed in a water bath at 25° C. The number of seconds it took for the solution to pass the marked line was measured (A seconds).

[0039] Also, 8 ml of OCP alone was used and the number of seconds it took for the solution to pass the marked line was measured using an Ostwald viscometer placed in a water bath at 25° C. in the same manner as above (B seconds).

[0040] The intrinsic viscosity was calculated using the following formula: IV=-1+[1+4×K×{(A / B)-1}]^0.5 / (2×K×C) Here, K is 0.343 and C is the concentration of the sample solution (g / 100 ml).

[0041] (4) Solution haze (unit: %) 2 g of the sample to be measured was dissolved in 20 mL of a 3 / 2 (volume ratio) mixed solution of OCP / 1,1,2,2-tetrachloroethane, placed in a cell with an optical path length of 20 mm, and measured by integrating sphere photoelectric photometry using a haze meter (manufactured by Suga Test Instruments Co., Ltd.) HGM-2DP type.

[0042] (5) Molecular chain scission rate before and after heat treatment (%BB) The polyester resin composition was vacuum dried at 150°C for 3 hours and then at 180°C for 7.5 hours, heat-melted in a nitrogen atmosphere at 290°C for 6 hours, and then quenched in water. The intrinsic viscosity (IV) was measured before and after this heat-melting treatment, and the molecular chain scission rate (%BB) was calculated by the following formula. %BB=0.27×((1 / T(after processing)^1.33)-1 / T(before processing)^1.33) T(before processing) = -0.703 + 3.21 x IV(before processing) - 2.13 x IV(before processing) ^ 2 + 0.527 x IV(before processing) ^ 3 T(after processing) = -0.703 + 3.21 x IV(after processing) - 2.13 x IV(after processing) ^ 2 + 0.527 x IV(after processing) ^ 3

[0043] (6) Evaluation of foreign matter in polyester resin composition 0.1 mg of the polyester resin composition was sandwiched between two cover glasses on a hot plate heated to 290° C. and melted to prepare a preparation on which a polymer thin film was formed. This preparation was observed under an optical microscope (Olympus Corporation: BX50, 400x, dark field) and all observable light spots were counted, and the number was used to make a judgment, with C being a failure. A: 0~5 pieces / 0.1mg B: 6~9 pieces / 0.1mg C: 10 or more / 0.1mg.

[0044] (Reference Example 1) Preparation of polyester resin composition A A slurry consisting of 86 parts by weight of terephthalic acid and 37 parts by weight of ethylene glycol (1.15 times the molar amount relative to terephthalic acid) was gradually added to an esterification reactor containing 105 parts by weight of bishydroxyethyl terephthalate (hereinafter referred to as BHT) melted at 250°C, and the esterification reaction was allowed to proceed. The temperature in the reaction system was controlled to be 245 to 250°C, and the esterification reaction was terminated when the reaction rate reached 95%.

[0045] 105 parts by weight (corresponding to 100 parts by weight of PET) of BHT was charged in a molten state from the esterification reactor into the polymerization apparatus, and the temperature was set to 255°C. An ethylene glycol solution of manganese acetate tetrahydrate (23 ppm as manganese element relative to the weight of the polyester resin composition) and a germanium dioxide solution (45 ppm as germanium element relative to the weight of the polyester resin composition) were added. Then, 5 parts by weight of ethylene glycol (0.15 times the molar ratio of the terephthalic component) were added to proceed with depolymerization, and then an ethylene glycol solution of phosphoric acid (19 ppm as phosphorus element relative to the weight of the polyester resin composition) and sodium dihydrogen phosphate dihydrate (14 ppm as sodium element, 19 ppm as phosphorus element relative to the weight of the polyester resin composition) was added. The germanium dioxide solution was an ethylene glycol solution obtained by dissolving germanium in a 20% aqueous solution of tetraethylammonium hydroxide and then adding ethylene glycol.

[0046] Thereafter, the temperature in the polymerization apparatus was gradually raised to 290°C, and the pressure was reduced from normal pressure to 133 Pa or less, and the polymerization reaction was carried out until a predetermined stirring torque was observed at 290°C. The entire amount of the distillate generated during this process was collected, and after the polymerization reaction was completed, the reaction system was returned to normal pressure with nitrogen gas, and the molten polyester in the polymerization apparatus was discharged in the form of strands into a water tank, cooled, and then cut to obtain a polyester resin composition in the form of pellets. The properties of the distillate and polyester resin composition obtained are shown in Table 1.

[0047] [Table 1]

[0048] Example 1 The distillate obtained in Reference Example 1 was transferred to a cooling tank and left to stand at a cooling temperature of 5°C for 2 hours, and the temperature of the distillate was set to 5°C. The distillate was then transferred from the bottom of the tank, filtered through a filter with a filtration accuracy of 4 μm, and then filtered through a filter with a filtration accuracy of 0.5 μm. The obtained solution was used in the same manner as in Reference Example 1 in an amount equivalent to 0.15 times the molar amount of the raw material ethylene glycol for the esterification reaction, and the esterification reaction was allowed to proceed. Thereafter, a polyester resin composition was obtained in the same manner as in Reference Example 1, except that the germanium dioxide solution added was 30 ppm in terms of germanium element relative to the weight of the polyester resin composition. The physical properties of the obtained polyester resin composition are shown in Table 2.

[0049] The polyester resin composition obtained in Example 1 was free of foreign matter and had good quality with no problem in terms of polymer properties.

[0050] [Table 2]

[0051] (Examples 2 to 5) A polyester resin composition was obtained in the same manner as in Example 1, except that the cooling temperature was changed as shown in Table 2, or cooling was not performed. The physical properties of the obtained polyester resin composition are shown in Table 2. The temperature of the distillate in Example 5, in which cooling was not performed, was 35°C, and was added while maintaining the temperature at 35°C when used as ethylene glycol, a raw material for the esterification reaction.

[0052] The polyester resin compositions obtained in Examples 2 and 3 were free of foreign matter and had satisfactory polymer properties.

[0053] The polyester resin compositions obtained in Examples 4 and 5 had slightly high turbidity in the solutions and foreign matter was found, but the quality was not problematic.

[0054] (Examples 6 and 7, Comparative Example 1) A polyester resin composition was obtained in the same manner as in Example 1, except that the distillate treatment conditions were changed as shown in Table 2, or cooling and filtration were not performed. The physical properties of the obtained polyester resin composition are shown in Table 2. The temperature of the distillate in Comparative Example 1, in which cooling was not performed, was 35°C, and was added while maintaining the temperature at 35°C when used as ethylene glycol, a raw material for the esterification reaction.

[0055] The polyester resin compositions obtained in Examples 6 and 7 had slightly high turbidity in the resulting solutions depending on the filtration accuracy, but the polymer properties were of a quality that did not pose any problems.

[0056] The polyester resin composition obtained in Comparative Example 1 was not cooled or filtered, and therefore the solution had high turbidity, and the amount of foreign matter in the polymer was large, resulting in poor polymer quality.

[0057] Example 8 The distillate obtained in Reference Example 1 was transferred to a cooling tank and left to stand at a cooling temperature of 5°C for 2 hours, and the temperature of the distillate was set to 5°C. The distillate was then transferred from the bottom of the tank, filtered through a filter with a filtration accuracy of 4 μm, and then filtered through a filter with a filtration accuracy of 0.5 μm. The obtained solution was transferred to a distillation apparatus capable of heating and stirring, and distilled and concentrated at a pressure of 15 kPa and a temperature of 150°C until the concentration ratio was about twice. The obtained residual liquid was used as 0.15 times the molar equivalent of the raw material ethylene glycol for the esterification reaction in the same manner as in Reference Example 1 to proceed with the esterification reaction. Thereafter, a polyester resin composition was obtained in the same manner as in Reference Example 1, except that the germanium dioxide solution added in the polymerization apparatus was 15 ppm as germanium element relative to the weight of the polyester resin composition. The physical properties of the obtained polyester resin composition are shown in Table 3.

[0058] The polyester resin composition obtained in Example 8 was free of foreign matter and had good quality with no problems in terms of polymer properties.

[0059] [Table 3]

[0060] (Examples 9 and 10, Comparative Example 2) A polyester resin composition was obtained in the same manner as in Example 6, except that the concentration ratio of the distillate was changed so that the Ge content of the treated solution was as shown in Table 3, and germanium dioxide was not added to the polymerization apparatus. The physical properties of the obtained polyester resin composition are shown in Table 3.

[0061] The polyester resin compositions obtained in Examples 9 and 10 were free of foreign matter and had satisfactory polymer properties.

[0062] The polyester resin composition obtained in Comparative Example 2 had high turbidity in the solution due to the concentration of the distillate, and the amount of foreign matter in the polymer was increased, resulting in poor polymer quality.

[0063] Example 11 The distillate obtained in Reference Example 1 was transferred to a cooling tank and left to stand at a cooling temperature of 5°C for 2 hours, and the temperature of the distillate was set to 5°C. The distillate was then transferred from the bottom of the tank, filtered through a filter with a filtration accuracy of 4 μm, and then filtered through a filter with a filtration accuracy of 0.5 μm to obtain a solution. The esterification reaction was carried out in the same manner as in Reference Example 1, and 10 ppm of germanium element out of the germanium dioxide added during the polycondensation reaction was added as a solution obtained by the above filtration, and the remaining 35 ppm was added as a germanium dioxide solution, and the rest was the same as in Reference Example 1 to obtain a polyester resin composition. The physical properties of the obtained polyester resin composition are shown in Table 3.

[0064] The polyester resin composition obtained in Example 11 was free of foreign matter and had good quality with no problems in terms of polymer properties.

[0065] Example 12 The distillate obtained in Reference Example 1 was transferred to a cooling tank and left to stand at a cooling temperature of 5°C for 2 hours, and the temperature of the distillate was set to 5°C. The distillate was then transferred from the bottom of the tank, filtered through a filter with a filtration accuracy of 4 μm, and then filtered through a filter with a filtration accuracy of 0.5 μm. Then, 101.0 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, and 4.6 parts by weight of the solution obtained by the above filtration were weighed and charged into an ester exchange reaction apparatus. The contents were dissolved at 150°C, and then an ethylene glycol solution of manganese acetate tetrahydrate (40 ppm as manganese element relative to the weight of the polyester resin composition) was added and stirred. Methanol was distilled off while increasing the temperature to 240°C, and the ester exchange reaction was terminated when a predetermined amount of methanol was distilled off. Thereafter, the reactants were transferred to a polymerization apparatus, and a germanium dioxide solution (30 ppm as germanium element relative to the weight of the polyester resin composition), phosphoric acid (19 ppm as phosphorus element relative to the weight of the polyester resin composition), and an ethylene glycol solution of sodium dihydrogen phosphate dihydrate (14 ppm as sodium element and 19 ppm as phosphorus element relative to the weight of the polyester resin composition) were added. The germanium dioxide solution was dissolved in a 20% aqueous solution of tetraethylammonium hydroxide, and then an ethylene glycol solution was added thereto. After the addition, the temperature inside the polymerization apparatus was gradually raised to 290°C, and the pressure was reduced from normal pressure to 133 Pa or less, and the polymerization reaction was carried out until a predetermined stirring torque was observed at 290°C. After the polymerization reaction was completed, the reaction system was returned to normal pressure with nitrogen gas, and the molten polyester in the polymerization apparatus was discharged in the form of a strand into a water tank, cooled, and then cut to obtain a pellet-shaped polyester resin composition. The properties of the obtained polyester resin composition are shown in Table 3.

[0066] The polyester resin composition obtained in Example 12 was free of foreign matter and had good quality with no problem in terms of polymer properties.

[0067] Example 13 The distillate obtained in Reference Example 1 was transferred to a cooling tank and left to stand at a cooling temperature of 5°C for 2 hours, and the temperature of the distillate was set to 5°C. The distillate was then transferred from the bottom of the tank, filtered through a filter with a filtration accuracy of 4 μm, and then filtered through a filter with a filtration accuracy of 0.5 μm to obtain a solution. The esterification reaction was carried out in the same manner as in Reference Example 1, and 105 parts by weight (corresponding to 100 parts by weight of PET) of BHT was charged in a molten state from the esterification reactor to the polymerization apparatus, and the temperature was set to 255°C. An ethylene glycol solution of manganese acetate tetrahydrate (23 ppm as manganese element relative to the weight of the polyester resin composition) and a germanium dioxide solution (39 ppm as germanium element relative to the weight of the polyester resin composition) were added. Thereafter, 5 parts by weight (0.15 times the molar amount relative to the terephthalic component) of the cooled and filtered distillate was added, followed by the addition of an ethylene glycol solution of phosphoric acid (19 ppm as phosphorus element relative to the weight of the polyester resin composition) and sodium dihydrogen phosphate dihydrate (14 ppm as sodium element and 19 ppm as phosphorus element relative to the weight of the polyester resin composition).The germanium dioxide solution was prepared by dissolving germanium dioxide in a 20% aqueous solution of tetraethylammonium hydroxide and then adding ethylene glycol to the solution.

[0068] Thereafter, the polymerization reaction was continued in the same manner as in Reference Example 1 to obtain a polyester resin composition. The properties of the obtained polyester resin composition are shown in Table 4.

[0069] The polyester resin composition obtained in Example 13 was free of foreign matter and had good quality with no problems in terms of polymer properties.

[0070] [Table 4]

[0071] (Examples 14 to 19, Comparative Example 3) A polyester resin composition was obtained in the same manner as in Example 13, except that the distillate treatment conditions were changed as shown in Table 4, or cooling and filtration were not performed. The physical properties of the obtained polyester resin composition are shown in Table 4. Note that the temperature of the distillate in Comparative Example 3, in which cooling was not performed, was 35°C, and was added to the polymerization reaction while maintaining the temperature at 35°C.

[0072] The polyester resin compositions obtained in Examples 14 and 15 were free of foreign matter and had satisfactory polymer properties.

[0073] The polyester resin compositions obtained in Examples 16 and 17 had slightly high turbidity in the solutions and foreign matter was found, but the quality was not problematic.

[0074] The polyester resin compositions obtained in Examples 18 and 19 had slightly high turbidity in the resulting solutions depending on the filtration accuracy, but the polymer properties were of a quality that did not pose any problems.

[0075] The polyester resin composition obtained in Comparative Example 3 was not cooled or filtered, and therefore the solution had high turbidity, and the amount of foreign matter in the polymer was large, resulting in poor polymer quality.

[0076] (Example 20) The distillate obtained in Reference Example 1 was transferred to a cooling tank and left to stand at a cooling temperature of 5°C for 2 hours, and the temperature of the distillate was set to 5°C. The distillate was then transferred from the bottom of the tank, filtered through a filter with a filtration accuracy of 4 μm, and then filtered through a filter with a filtration accuracy of 0.5 μm. The obtained solution was transferred to a distillation apparatus capable of heating and stirring, and distilled and concentrated at a pressure of 15 kPa and a temperature of 150°C until the concentration ratio became about twice, to obtain a solution. The esterification reaction was carried out in the same manner as in Reference Example 1, and 105 parts by weight (corresponding to 100 parts by weight of PET) of BHT was charged in a molten state from the esterification reactor to the polymerization apparatus, and the temperature was set to 255°C. An ethylene glycol solution of manganese acetate tetrahydrate (23 ppm as manganese element relative to the weight of the polyester resin composition) and a germanium dioxide solution (32 ppm as germanium element relative to the weight of the polyester resin composition) were added. Thereafter, 5 parts by weight (0.15 times the molar amount relative to the terephthalic component) of the cooled and filtered distillate was added, followed by the addition of an ethylene glycol solution of phosphoric acid (19 ppm as phosphorus element relative to the weight of the polyester resin composition) and sodium dihydrogen phosphate dihydrate (14 ppm as sodium element and 19 ppm as phosphorus element relative to the weight of the polyester resin composition).The germanium dioxide solution was prepared by dissolving germanium dioxide in a 20% aqueous solution of tetraethylammonium hydroxide and then adding ethylene glycol to the solution.

[0077] Thereafter, the polymerization reaction was continued in the same manner as in Reference Example 1 to obtain a polyester resin composition. The properties of the obtained polyester resin composition are shown in Table 5.

[0078] The polyester resin composition obtained in Example 20 was free of foreign matter and had good quality with no problem in terms of polymer properties.

[0079] [Table 5]

[0080] Example 21 A polyester resin composition was obtained in the same manner as in Example 20, except that the concentration ratio of the distillate was changed so that the Ge content of the treated solution would be as shown in Table 5, and 27 ppm of germanium element was added to the germanium dioxide solution in the polymerization apparatus relative to the weight of the polyester resin composition. The physical properties of the obtained polyester resin composition are shown in Table 5.

[0081] The polyester resin composition obtained in Example 21 was free of foreign matter and had good quality with no problem in terms of polymer properties.

[0082] Example 22 A polyester resin composition was obtained in the same manner as in Example 20, except that the concentration ratio of the distillate was changed so that the Ge content of the treated solution would be as shown in Table 5, and 19 ppm of germanium element was added to the germanium dioxide solution in the polymerization apparatus relative to the weight of the polyester resin composition. The physical properties of the obtained polyester resin composition are shown in Table 5.

[0083] The polyester resin composition obtained in Example 22 contained some foreign matter, but had no problem with its quality.

[0084] Comparative Example 4 A polyester resin composition was obtained in the same manner as in Example 20, except that the concentration ratio of the distillate was changed so that the Ge content of the treated solution would be as shown in Table 5, and 13 ppm of germanium element was added to the germanium dioxide solution in the polymerization apparatus relative to the weight of the polyester resin composition. The physical properties of the obtained polyester resin composition are shown in Table 5.

[0085] The polyester resin composition obtained in Comparative Example 4 had high turbidity in the solution due to the concentration of the distillate, and the amount of foreign matter in the polymer was increased, resulting in poor polymer quality.

[0086] (Example 23) The distillate obtained during the polymerization reaction in Example 1 was used in an amount equivalent to 0.15 times the molar amount of ethylene glycol, the raw material for the esterification reaction, in the same manner as in Example 1 to obtain a polyester resin composition. The physical properties of the obtained polyester resin composition are shown in Table 5.

[0087] The polyester resin composition obtained in Example 23 was free of foreign matter and had good quality with no problems in terms of polymer properties.

[0088] (Example 24) The distillate obtained during the polymerization reaction in Example 1 was added again during the polycondensation reaction in the same manner as in Example 13 to advance the polymerization reaction, thereby obtaining a polyester resin composition. The properties of the obtained polyester resin composition are shown in Table 5.

[0089] The polyester resin composition obtained in Example 24 was free of foreign matter and had satisfactory polymer properties.

[0090] (Example 25) The distillate obtained in Reference Example 1 was treated in the same manner as in Example 13 to obtain a solution. The esterification reaction was carried out in the same manner as in Reference Example 1, and 105 parts by weight (corresponding to 100 parts by weight of PET) of BHT was charged in a molten state from the esterification reactor to the polymerization apparatus, and the temperature was set to 255°C. An ethylene glycol solution of manganese acetate tetrahydrate (23 ppm as manganese element relative to the weight of the polyester resin composition) and a germanium dioxide solution (39 ppm as germanium element relative to the weight of the polyester resin composition) were added. Then, an ethylene glycol solution of phosphoric acid (19 ppm as phosphorus element relative to the weight of the polyester resin composition) and sodium dihydrogen phosphate dihydrate (14 ppm as sodium element, 19 ppm as phosphorus element relative to the weight of the polyester resin composition) was added, and then 5 parts by weight of the distillate that had been cooled and filtered was added (0.15 times the molar amount relative to the terephthalic component). The germanium dioxide solution was prepared by dissolving germanium dioxide in a 20% aqueous solution of tetraethylammonium hydroxide, and then adding ethylene glycol to the solution to obtain an ethylene glycol solution.

[0091] Thereafter, the polymerization reaction was continued in the same manner as in Reference Example 1 to obtain a polyester resin composition. The properties of the obtained polyester resin composition are shown in Table 5.

[0092] The polyester resin composition obtained in Example 25 contained some foreign matter, but had an acceptable quality.

Claims

1. The method for producing a polyester resin composition comprises carrying out an esterification reaction (A) between a dicarboxylic acid component and a diol component, or an ester exchange reaction (B) between a dicarboxylic acid ester-forming derivative component and a diol component, and then carrying out a polycondensation reaction (C) to produce a polyester resin composition, in which a distillate from the polycondensation reaction is recovered and the distillate is used in any one of the above reactions (A) to (C) as a solution that satisfies the following formulas (i) and (ii): Turbidity ≦ 100 NTU (i) Germanium element (atomic) content ≦600 ppm (weight ratio to the solution) (ii)

2. The method for producing a polyester resin composition according to claim 1, wherein the solution is obtained by cooling and / or filtering a distillate.

3. The method for producing a polyester resin composition according to claim 2, wherein the cooling temperature is less than 15°C.

4. The method for producing a polyester resin composition according to claim 2, wherein the filtration is carried out in two or more stages.

5. 2. The method for producing a polyester resin composition according to claim 1, wherein the polyester is polyethylene terephthalate.

6. An apparatus for producing a polyester resin composition, comprising: a step of performing an esterification reaction (A) between a dicarboxylic acid component and a diol component, or a transesterification reaction (B) between a dicarboxylic acid ester-forming derivative component and a diol component; a step of performing a subsequent polycondensation reaction (C); a step of recovering a distillate from the polycondensation reaction; a step of purifying the distillate to obtain a solution; and a step of sending the obtained solution that satisfies the following formulas (iii) and (iv) to any one of the above reaction steps. Turbidity≦100NTU (iii) Germanium element (atomic) content ≦600 ppm (weight ratio to the solution) (iv)

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