JP7290122B2 - Method for producing polyester composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a particle-containing polyester composition which has a small amount of linear oligomer scattering, and has good hydrolysis resistance and particle dispersibility, and a method for producing the same.

Polyester is excellent in mechanical properties, thermal properties, chemical resistance, electrical properties and moldability, and is used in various applications. Among polyesters, polyethylene terephthalate (hereinafter referred to as PET) is particularly excellent in transparency and workability, and is widely used in applications requiring high quality such as optical films and release films.
However, linear oligomers such as PET monomer components and low-molecular-weight substances (oligomer components) are generated and increased by the decomposition reaction of polyester, which evaporates and scatters during molding and processing, which may cause surface contamination of molded products. . In addition, the scattering of the linear oligomer may cause contamination in the process, which causes the problem of deterioration of the quality of the molded product due to surface contamination and process contamination.
In addition, in order to impart antiblocking properties, slip properties, hiding properties, wear resistance, design properties, UV resistance, etc. to polyester molded articles, it is common practice to add particles to the polyester composition. there is However, the hydrolysis of the polyester due to the activity of the particles themselves or the decomposition of the polyester composition during melt-kneading at high temperatures increases the amount of COOH terminal groups, resulting in poor hydrolysis resistance.
In order to solve these problems, studies have been made as shown in the following documents.
Patent Documents 1 and 2 describe that hydrolysis resistance is improved by adding an alkali metal phosphate to the polyester resin.
Patent Document 3 discloses a technique for reducing the content of cyclic trimers by specifying the equivalent ratio of metal atoms (elements) and phosphorus atoms (elements) in PET.
Patent Document 4 discloses a technique for providing a polyester composition having excellent particle dispersibility and heat resistance by using surface-treated particles.

WO2014/021095 JP 2013-189521 A JP-A-4-183745 JP-A-8-143756

As in the prior art described above, there is a problem that the effect of suppressing scattering of linear oligomers and thermal stability are insufficient only by improving hydrolysis resistance. If only reducing cyclic trimers, which are oligomers, there is no effect on linear oligomers, which are generated and increased by different mechanisms such as thermal decomposition and hydrolysis during melting, so surface contamination of products and processing processes are not effective. Couldn't keep it from getting dirty. In addition, generation of linear oligomers could not be suppressed only by using surface-treated particles. That is, the conventional techniques for improving hydrolysis resistance, suppressing cyclic trimers, and treating the surface of particles could not achieve the effect of suppressing scattering of linear oligomers.

SUMMARY OF THE INVENTION An object of the present invention is to provide a particle-containing polyester composition which has a small amount of linear oligomer scattering, and has good hydrolysis resistance and particle dispersibility, and a method for producing the same.

The object of the present invention is achieved by the following means.

( 1 ) When producing a polyethylene terephthalate composition by subjecting a dicarboxylic acid or a dicarboxylic acid ester and a diol to an esterification reaction or a transesterification reaction, followed by a polycondensation reaction, a compound containing an Mn atom (element), sodium metal phosphate Particles that are at least one selected from the group consisting of salts or potassium phosphate metal salts, acidic compounds containing P atoms (elements), and calcium carbonate, silicon dioxide, titanium dioxide, and aluminum oxide with a volume average diameter of 3.0 μm or less . is added before the end of the polycondensation reaction, the added amount satisfies the formulas (V) and (VI), and the particles and the acidic compound are mixed and then added.
5 ppm ≤ Mn atom (element) addition amount (weight ratio to polyethylene terephthalate composition) ≤ 50 ppm (V)
5 ppm ≤ added amount of alkali metal atom (element) (weight ratio to polyethylene terephthalate composition) ≤ 100 ppm (VI)
( 2 ) The method for producing a polyethylene terephthalate composition according to ( 1 ), wherein the particles and the acidic compound are mixed for 10 seconds or longer.

The present invention provides a particle-containing polyester composition that has a small amount of linear oligomer scattering, and has good hydrolysis resistance and particle dispersibility, and a method for producing the same.

The present invention will be described in detail below.
The polyester composition of the present invention is a polyester composition characterized by satisfying formulas (I) to (III), further containing particles, and containing P atoms (elements) on the particle surfaces.
Linear oligomer scattering amount (weight ratio to polyester composition) ≤ 20 ppm (I)
5 ppm ≤ Mn atom (element) content (weight ratio to polyester composition) ≤ 50 ppm (II)
5 ppm ≤ alkali metal atom (element) content (weight ratio to polyester composition) ≤ 100 ppm (III)
The polyester composition of the present invention must have a scattering amount of linear oligomers of 20 ppm or less based on the weight of the polyester composition. The procedure for measuring the amount of linear oligomer scattering is as follows: As a pretreatment, the polyester composition is vacuum-dried at 150° C. for 3 hours and further at 180° C. for 7.5 hours, and this polyester composition is dried at 290° C. for 30 minutes under nitrogen flow. After heating and melting, it is quenched in water. The resulting composition is cut into chips and dried under vacuum for 3 hours at room temperature. Next, it is the scattering amount of the linear oligomer when the obtained composition is heat-treated in the air at 220° C. for 8 hours and the scattered linear oligomer is captured by a cooling plate.

In the present invention, the linear oligomer means a polyester monomer component or an oligomer component, and specifically, a dicarboxylic acid component constituting the polyester, or a chain-like oligomer obtained by reacting the carboxyl group of the dicarboxylic acid with the hydroxyl group of the diol. and does not include cyclic oligomers such as cyclic trimers. Specifically, they are monoesters and diesters with dicarboxylic acid monomers and glycol components. This linear oligomer easily sublimes or precipitates, and causes process contamination and surface contamination of molded products in processing steps such as melt molding.

Examples of typical polyesters such as PET include TPA (terephthalic acid), MHT (monohydroxyethyl terephthalate) and BHT (bishydroxyethyl terephthalate), which are reaction products of terephthalic acid and ethylene glycol. The total amount of these linear oligomers must be 20 ppm or less, preferably 15 ppm or less. By setting the scattering amount of the linear oligomer within the above range, it is possible to reduce process contamination and surface contamination caused by the linear oligomer, which is a problem during molding.
The polyester composition of the present invention must contain Mn atoms (elements) (manganese atoms (elements)) in an amount of 5 ppm or more and 50 ppm or less based on the weight of the polyester composition.
The lower limit is preferably 10 ppm or more. Further, the upper limit is preferably 40 ppm or less, more preferably 30 ppm or less. Thermal stability can be improved by making it equal to or higher than the above lower limit. In addition, Mn atoms (elements) contribute to thermal decomposition, oxidative decomposition, and hydrolysis of polyester because they have high catalytic activity even in heat treatment at a relatively low temperature below the melting point of polyester, such as in a film stretching process. Therefore, by satisfying the amount of Mn atoms (elements) equal to or less than the above upper limit, it becomes possible to reduce the amount of linear oligomers generated in the processing step.

Moreover, the polyester composition of the present invention must contain alkali metal atoms (elements) in an amount of 5 ppm or more and 100 ppm or less based on the weight of the polyester composition.
The lower limit is preferably 10 ppm or more. The upper limit is preferably 60 ppm or less, more preferably 30 ppm or less. Within the above range, the hydrolysis resistance is improved, and the generation of linear oligomers due to hydrolysis can be suppressed. From the viewpoint of excellent hydrolysis resistance, the alkali metal atom (element) is preferably sodium or potassium.

Moreover, the polyester composition of the present invention must contain a P atom (element) (phosphorus atom (element)). By containing P atoms (elements), it is possible to impart hydrolysis resistance to the polyester composition and further improve particle dispersibility. Furthermore, it is preferable that P atoms (elements) are also contained on the particle surface. By protecting the particle surface with P atoms (elements), the particles are less likely to agglomerate even when subjected to heat history, etc., making it possible to provide a polyester composition having good particle dispersibility. Whether P atoms (elements) are present on the particle surface is determined by the method described in Example (7) below.

Although the content of P atoms (elements) in the polyester composition is not particularly defined, the lower limit is preferably 15 ppm or more, more preferably 25 ppm or more, based on the weight of the polyester composition. Further, the upper limit is preferably 90 ppm or less. By setting it as the above range, it is possible to impart good hydrolysis resistance and particle dispersibility to the polyester composition.

Although the type of particles used in the present invention is not particularly limited, inorganic particles are preferred from the viewpoint of thermal stability, hydrolysis resistance and particle dispersibility. For example, calcium carbonate, silicon dioxide, titanium dioxide, aluminum oxide, calcium phosphate, calcium fluoride, zinc carbonate, zinc oxide, zinc sulfide, cerium oxide, magnesium oxide, barium sulfate and carbon black can be used. It may also be a mixture of particles or a compound such as a composite oxide. It is more preferable to use calcium carbonate, silicon dioxide, titanium dioxide, and aluminum oxide from the viewpoint of particle dispersibility and imparting of excellent antiblocking properties when molded.

Although the particle diameter of the particles of the present invention is not limited, when the volume average diameter of the particles in the polyester composition is 3.0 μm or less, it is possible to provide a polyester composition having good particle dispersibility. More preferably, the volume average diameter is 2.0 μm or less, and even more preferably 1.5 μm or less.
Although the content of the particles of the present invention is not particularly limited, the lower limit of the content is preferably 0.1 wt % or more. The upper limit is preferably 5.0 wt% or less, more preferably 2.0 wt% or less. Within the above range, the particle dispersibility and the anti-blocking property of the molded article are excellent.
The polyester composition of the present invention preferably has a particle variation represented by the following formula (IV) of 1.5 or less. It is more preferably 1.2 or less, still more preferably 1.0, that is, not increasing.

Particle change amount = (particle content after heat treatment (wt%)) / (particle content before heat treatment (wt%)) (IV)
(Heat treatment: under nitrogen atmosphere, 300°C, 10 hours)
Since the polyester composition of the present invention contains P atoms (elements) on the particle surfaces, it has good particle dispersibility and can prevent morphological changes of the particles due to thermal deterioration. When heat deterioration occurs, elution occurs from the particle surface, and a by-product with the polyester composition is generated. When this by-product is generated, the weight of the polyester composition increases, so the number of particles obtained by isolation increases, and the variation exceeds 1.0. A method for measuring this amount of change will be described in Example (6) below.
The polyester composition of the present invention preferably has a COOH terminal group content of 30 eq/t or less. Further, it is more preferably 20 eq/t or less, further preferably 15 eq/t or less. By setting the amount within the above range, it is possible to impart good hydrolysis resistance to the obtained polyester composition, and it is possible to suppress the generation of linear oligomers due to hydrolysis.

The hydrolysis resistance of the polyester composition of the present invention is evaluated by the value of ΔCOOH/COOH. ΔCOOH is the amount of increase in COOH terminal groups when subjected to wet heat treatment at 155° C. for 4 hours under saturated steam. becomes good. The polyester composition of the present invention preferably has a ΔCOOH/COOH value of 10.0 or less. When the value of ΔCOOH/COOH is 10.0 or less, the hydrolysis resistance is good and generation of linear oligomers due to hydrolysis can be suppressed. The value of ΔCOOH/COOH is more preferably 8.0 or less, even more preferably 7.0 or less.

The dispersibility of particles contained in the polyester composition of the present invention is evaluated by the solution haze of the polyester composition. The smaller the solution haze, the better the transparency and particle dispersibility of the polyester composition.

The solution haze of the polyester composition is preferably 50% or less. It is more preferably 40% or less, still more preferably 35% or less. By satisfying the above range, it is possible to provide a polyester composition suitable for films that require smooth surface properties.

The polyester constituting the polyester composition of the present invention is preferably PET from the viewpoint of sufficiently exhibiting the hydrolysis resistance and particle dispersibility, which are the effects of the present invention. Further, a copolymer component may be contained within a range that does not impair the effects of the present invention.

Next, a method for producing the polyester composition of the present invention will be described.
The method for producing the polyester composition of the present invention uses a dicarboxylic acid component or its ester and a diol component as main raw materials, and comprises the following two steps. That is, the first-stage process consisting of (A) an esterification reaction or (B) a transesterification reaction, and the subsequent second-stage process consisting of (C) a polycondensation reaction.

A dicarboxylic acid or a dicarboxylic acid ester and a diol can be used as raw materials for producing the polyester composition of the present invention, and it is also possible to use a combination of two or more kinds.

The dicarboxylic acids of the present invention include terephthalic acid, 2,6-naphthalene dicarboxylic acid, isophthalic acid, diphenyl 4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, malonic acid. acid, dimer acid and the like. Further, dicarboxylic acid esters are lower alkyl esters, acid anhydrides, acyl chlorides and the like of the aforementioned dicarboxylic acids, and methyl esters, ethyl esters, hydroxyethyl esters and the like are preferably used. A more preferable embodiment of the dicarboxylic acid or dicarboxylic acid ester of the present invention is terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, in that a polyester composition having a high melting point and being easily processed into films, fibers, etc. can be obtained. acids, or alkyl esters thereof.

Diols of 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 alicyclic diols include saturated alicyclic primary diols such as cyclohexanedimethanol, cyclohexanediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecanediethanol, decalindimethanol and decalindiethanol, and isosorbide. Saturated heterocyclic primary diols including cyclic ethers, other cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxy ethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentanediol, 4-cyclopentene-1,3-diol, adamantanediol and other alicyclic diols, paraxylene glycol, bisphenol A, Bisphenol S, styrene glycol, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9'-bis(4-hydroxyphenyl)fluorene and other aromatic ring diols can be exemplified. In addition to diols, polyfunctional alcohols such as trimethylolpropane and pentaerythritol can also be used as long as they do not impair the effects of the present invention. Ethylene glycol is preferred in that the effects of the present invention can be sufficiently achieved and in that a polyester composition that can be easily processed into films, fibers, and the like can be obtained.

In the production method of the present invention, among the steps of the first step, (A) the step of esterification reaction is to esterify a dicarboxylic acid and a diol at a predetermined temperature, and the reaction is continued until a predetermined amount of water is distilled. to obtain a low polymer. When obtaining a low polymer by an esterification reaction, from the viewpoint of esterification reactivity and heat resistance, the molar ratio of dicarboxylic acid and diol (diol/dicarboxylic acid) before the start of the esterification reaction is 1.05 or more and 1.40. The following ranges are preferred. It is more preferably 1.05 or more and 1.30 or less, still more preferably 1.05 or more and 1.20 or less. When the amount is within the above range, good reactivity can be obtained, and the formation of by-products such as dimers of diols can be suppressed, so that heat resistance can be improved.

In the step (B) of transesterification, a dicarboxylic acid alkyl ester and a diol are transesterified, and the reaction is continued until a predetermined amount of alcohol is distilled to obtain a low polymer. When obtaining a low polymer by transesterification, the molar ratio of dicarboxylic acid alkyl ester and diol (diol/dicarboxylic acid alkyl ester) is in the range of 1.7 to 2.3 from the viewpoint of reactivity and heat resistance. Preferably. By setting the amount within the above range, the transesterification reaction can be efficiently progressed, and the by-production of diol dimer can be suppressed, so that the heat resistance can be improved.

Among the steps of the second step, (C) polycondensation reaction is a step of obtaining a polyester composition from the low polymer obtained by (A) esterification reaction or (B) transesterification reaction.

Moreover, batch polymerization, semi-continuous polymerization, and continuous polymerization can be applied to the production method of the present invention.

In the method for producing the polyester composition of the present invention, (A) the catalyst used in the esterification reaction may be a compound such as manganese, cobalt, zinc, titanium, calcium, etc., but the heat in the polycondensation reaction stage may be used. From the viewpoint of decomposition and generation of foreign matter, it is preferable to carry out the esterification reaction without a catalyst. Here, (A) the esterification reaction proceeds sufficiently even in the absence of a catalyst due to the self-catalytic action of the carboxylic acid. Moreover, a well-known transesterification catalyst can be used as a catalyst used for (B) transesterification reaction. Examples of transesterification catalysts include organic manganese compounds, organic magnesium compounds, organic calcium compounds, organic cobalt compounds, and organic lithium compounds. There are things, but it is not limited to these.

Moreover, the catalyst used for (C) polycondensation reaction can use a well-known polycondensation catalyst. Examples include compounds such as antimony, titanium, aluminum, tin and germanium.

Antimony compounds include antimony oxides, antimony carboxylates, antimony alkoxides, and the like.
Titanium compounds include titanium chelate complexes, titanium alkoxides, and titanium oxides obtained by hydrolysis of titanium alkoxides.

Aluminum compounds include aluminum carboxylates, aluminum alkoxides, aluminum chelate compounds, basic aluminum compounds, and the like.

Examples of tin compounds include tin compounds having an alkyl group and tin compounds having a hydroxyl group.

Germanium compounds include germanium oxides and germanium alkoxides.

The above metal compounds may be hydrates.
Among these, it is preferable to use an antimony compound as a polycondensation reaction catalyst from the viewpoint of polymerization time and economy.

In the method for producing a polyester composition of the present invention, a compound containing a Mn atom (element), a compound containing an alkali metal atom (element), an acidic compound and particles are added before the end of the polycondensation reaction, and the amount added is the formula It is necessary to satisfy (V) and (VI), mix the particles and the acidic compound, and then add them.
5 ppm ≤ Mn atom (element) addition amount (weight ratio to polyester composition) ≤ 50 ppm (V)
5 ppm ≤ alkali metal atom (element) addition amount (weight ratio to polyester composition) ≤ 100 ppm (VI)
In the method for producing the polyester composition of the present invention, the compound containing an Mn atom (element), the compound containing an alkali metal atom (element), the acidic compound and the particles are the (A) esterification reaction or (B) transesterification step , It may be added at any stage of the subsequent (C) polycondensation reaction step, but by adding it before the end of the polycondensation reaction and after mixing the acidic compound and the particles, the amount of COOH terminal groups is reduced and the resistance is reduced. It is possible to improve the hydrolyzability, suppress the generation of linear oligomers due to hydrolysis, and obtain a polyester composition having good particle dispersibility.

The amount of Mn atoms (elements) added to the polyester composition of the present invention must be 5 ppm or more and 50 ppm or less based on the weight of the polyester composition.

The lower limit of the amount of Mn atoms (elements) to be added is preferably 10 ppm or more. Further, the upper limit is preferably 40 ppm or less, more preferably 30 ppm or less. Thermal stability can be improved by making it equal to or higher than the above lower limit. In addition, Mn atoms (elements) contribute to thermal decomposition, oxidative decomposition, and hydrolysis of polyester because they have high catalytic activity even in heat treatment at a relatively low temperature below the melting point of polyester, such as in a film stretching process. Therefore, by satisfying the amount of Mn atoms (elements) equal to or less than the above upper limit, it becomes possible to reduce the amount of linear oligomer scattering in the processing step.

The compound containing a Mn atom (element) is not particularly limited, but examples include manganese acetate, manganese nitrate, manganese chloride, manganese sulfate, etc. Manganese acetate is preferred from the viewpoint of solubility and catalytic activity.

Moreover, the form of addition may be powder, slurry, or solution, and from the viewpoint of dispersibility, it is preferable to add as a solution. The solvent at this time is preferably the same as the diol component of the polyester composition. For example, it is particularly preferable to use ethylene glycol in the case of PET.

The amount of alkali metal atoms (elements) added to the polyester composition of the present invention must be 5 ppm or more and 100 ppm or less based on the weight of the polyester composition. The lower limit is preferably 10 ppm or more. Further, the upper limit is preferably 60 ppm or less, more preferably 30 ppm or less. Within the above range, the hydrolysis resistance is improved, and the scattering of linear oligomers caused by hydrolysis can be suppressed.

A compound containing an alkali metal atom (element) is not particularly limited. Examples include phosphates, hydroxides, acetates, carbonates, nitrates and chlorides of lithium, sodium and potassium. From the viewpoint of hydrolysis resistance, it is preferably a compound containing sodium or potassium, more preferably sodium metal phosphate or potassium metal phosphate. Sodium phosphate metal salts or potassium phosphate metal salts include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, and tripotassium phosphate. . Sodium dihydrogen phosphate or potassium dihydrogen phosphate is particularly preferred from the viewpoint of hydrolysis resistance. Also, a plurality of alkali metal phosphates may be used in combination.

Further, the above alkali metal phosphate may be used in combination with an alkali metal compound other than the alkali metal phosphate. For example, by using potassium hydroxide together, it is possible to reduce the melting specific resistance of the polyester required for electrostatic film formation, and improve moldability.

The compound containing an alkali metal atom (element) may be added in any form of powder, slurry, or solution, and is preferably added as a solution from the viewpoint of dispersibility. The solvent at this time is preferably the same as the diol component of the polyester composition, and in the case of PET, it is particularly preferable to use ethylene glycol.

The acidic compound in the present invention refers to a compound having pH<7 in an aqueous solution, and is not particularly limited. From the viewpoint of hydrolysis resistance and heat resistance, it is preferable to add a phosphorus compound as an acidic compound. Phosphoric acid, trimethylphosphoric acid, ethyldiethylphosphonoacetate, phosphorous acid, and the like can be used as the phosphorus compound, and it is also possible to use a plurality of phosphorus compounds in combination. It is particularly preferred that the phosphorus compound is phosphoric acid or trimethylphosphoric acid. By mixing and adding the phosphorus compound and the particles, the phosphorus compound adheres to the surface of the particles and protects the particles, making it difficult for the particles to agglomerate even when subjected to heat history, etc., and improving the dispersibility of the particles. .

The amount of the acidic compound added is not particularly specified, but when a phosphorus compound is used as the acidic compound, the content of P atoms (elements) in the polyester composition is 30 ppm or more and 80 ppm or less with respect to the weight of the polyester composition. addition is preferred. By setting it as the above range, it is possible to impart good hydrolysis resistance and particle dispersibility to the polyester composition.

In the method for producing a polyester composition of the present invention, (A) when carried out via an esterification reaction, after the esterification reaction, a compound containing an alkali metal atom (element), an acidic compound and particles are added. Additional addition of a glycol component such as ethylene glycol is preferably carried out. More preferably, after adding the manganese compound, before adding the compound containing an alkali metal atom (element), the acidic compound, and the particles. Since the low-molecular weight product of the polyester composition obtained by the esterification reaction has a higher degree of polymerization than the low-molecular weight product obtained by the transesterification reaction, it is difficult for the alkali metal phosphate to disperse, and contaminants easily occur. Therefore, by additionally adding a glycol component such as ethylene glycol and lowering the degree of polymerization by depolymerization, foreign substances can be suppressed. At this time, the presence of a manganese compound enables more efficient depolymerization.

The additionally added glycol component such as ethylene glycol is preferably 0.05- to 0.5-fold mol with respect to the total acid component. It is more preferably 0.1-fold mol or more and 0.3-fold mol or less. Within the above range, it is possible to prevent the alkali metal phosphate from becoming a foreign matter without delaying the polymerization time due to the temperature drop in the polymerization system.

In the method for producing the polyester composition of the present invention, the type of particles to be added is not particularly specified, but inorganic particles are preferred from the viewpoint of thermal stability, hydrolysis resistance and particle dispersibility. For example, calcium carbonate, silicon dioxide, titanium dioxide, aluminum oxide, calcium phosphate, calcium fluoride, zinc carbonate, zinc oxide, zinc sulfide, cerium oxide, magnesium oxide, barium sulfate and carbon black can be used. It may also be a mixture of particles or a compound such as a composite oxide. Calcium carbonate, silicon dioxide, titanium dioxide, and aluminum oxide are more preferably used in terms of particle dispersibility and excellent anti-blocking properties when molded.

The form of addition of the acidic compound and particles may be either powder or slurry, and from the standpoint of particle dispersibility, it is preferable to add as slurry. When added as a slurry, it is preferable that the particles and the dispersing solvent are sufficiently mixed, so mixing is preferably performed for at least 10 seconds. Mixing may be performed using a stirring device such as a stirrer or a magnetic stirrer. Moreover, the particle dispersion solvent is preferably the same as the diol component of the polyester composition, and in the case of PET, it is particularly preferable to use ethylene glycol.

It is preferable to stir the inside of the reaction system during and after the addition of the compound containing an Mn atom (element), the compound containing an alkali metal atom (element), the acidic compound, and the particles. Additives can be dispersed more uniformly by stirring.

In addition, in the method for producing the polyester composition of the present invention, solid-phase polymerization may be carried out in order to obtain a high-molecular-weight polyester composition. The solid phase polymerization is carried out by heat-treating the polyester composition in an inert gas atmosphere or under reduced pressure, although the apparatus and method are not particularly limited. The inert gas may be any gas as long as it is inert to the polyester composition, and examples thereof include nitrogen, helium, carbon dioxide gas, etc. Nitrogen is preferably used from the economical point of view. Further, in the reduced pressure condition, it is advantageous to use a higher vacuum because the time required for the solid-phase polymerization reaction can be shortened, and specifically, it is preferable to keep the pressure at 110 Pa or less.

Specific examples of the method for producing the polyester composition of the present invention are given below, but the present invention is not limited thereto.

A slurry of terephthalic acid and ethylene glycol (1.15 times the moles of terephthalic acid) was gradually added to an esterification reactor charged with dissolved bishydroxyethyl terephthalate (BHT) at 250°C, and an esterification reaction was started. proceed. The temperature in the reaction system is controlled to 245-250° C., and the esterification reaction is terminated when the reaction rate reaches 95%.

The esterification reaction product thus obtained at 255° C. is transferred to a polymerization apparatus, and a compound containing an Mn atom (element), a compound containing an alkali metal atom (element), a mixture of particles and an acidic compound, a polycondensation catalyst, etc. are added. do. During these operations, it is preferable to keep the temperature in the system at 240 to 255° C. so that the esterified product does not solidify.

After that, 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 250 Pa or less to distill ethylene glycol. The reaction is terminated when a predetermined stirring torque is reached, the inside of the reaction system is brought to normal pressure with nitrogen gas, and the molten polyester is extruded into cold water into strands and cut to obtain a polyester composition.

The polyester composition obtained in the present invention can be molded by a known molding method, and can be processed into various products such as films, fibers, bottles and injection molded products.

When processing the polyester composition of the present invention into each product, various additives such as coloring agents including pigments and dyes, lubricants, antistatic agents, flame retardants, and ultraviolet absorbers within a range that does not impair the effects of the present invention. , an antibacterial agent, a nucleating agent, a plasticizer, and a release agent.

The polyester composition of the present invention is excellent in hydrolysis resistance, thermal stability and particle dispersibility, and has a small amount of gel composition and linear oligomer scattering generated during melt molding and processing steps. Therefore, it can be used as various products such as films, fibers, bottles, and injection-molded products, and in particular, it can be used for high-quality films such as optical films and release films.

The film may be a monolayer film composed of the polyester composition of the present invention or a laminated film having at least one layer of the polyester composition of the present invention. Particularly in the case of laminated films, preferred are laminated films having a layer comprising the polyester composition of the present invention on at least one surface thereof. When the layer composed of the polyester composition of the present invention is present on the film surface, volatilization of linear oligomers from the film surface is suppressed, so that the generation of linear oligomer defects can be effectively suppressed.

Molded articles produced from the polyester composition of the present invention are excellent in heat stability and color tone, and therefore are used as agricultural materials, gardening materials, fishery materials, civil engineering and construction materials, stationery, medical supplies, automobile parts, It is useful for electric/electronic parts or other uses, and in particular, biaxially stretched film is suitable for release process film and optical film.

The present invention will be described in more detail with reference to the following examples. In addition, physical property values in the examples were measured by the following methods. The method described below describes the measurement method in the case of a single component of the polyester composition of the present invention, but in the case of a molded product composed of a plurality of resins such as a laminated film, the resin of each layer is scraped out. Isolate and analyze.
Also, Examples 13 to 15 and Example 21 should be read as Reference Examples.

(1) Intrinsic viscosity of polyester composition (unit: dl/g)
0.1 g of the polyester resin composition was weighed with an accuracy of within 0.001 g, 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, 8 ml of the solution was charged into an Ostwald viscometer placed in a water bath at 25° C., and the number of seconds passed through the marked line was measured (A seconds).
In addition, using 8 ml of OCP alone, the number of seconds for passing through the marked line was measured with an Ostwald viscometer placed in a water bath at 25° C. in the same manner as described above (B seconds).

The intrinsic viscosity was calculated by 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 (g/100 ml) of the sample solution.

(2) COOH terminal group amount of polyester composition (unit: eq/t)
It was measured by the method of Maurice (reference MJ Maurice, F. Huizinga, Anal. Chem. Acta, 22, 363 (1960)).
That is, 0.5 g of the polyester resin composition is weighed with an accuracy within 0.001 g. 50 ml of a solvent obtained by mixing o-cresol/chloroform at a mass ratio of 7/3 is added to the sample, heated to an internal temperature of 90° C., and then heated and stirred for 20 minutes to dissolve the sample. Also, the mixed solvent alone is similarly heated separately as a blank solution. The solution is cooled to room temperature and titrated with a 1/50N potassium hydroxide methanol solution using a potentiometric titrator. Titration is also carried out in the same manner for a blank solution containing only the mixed solvent.
The amount of COOH terminal groups in the polyester resin composition was calculated by the following formula.
COOH end group amount (eq/t) = {(V1-V0) x N x f} x 1000/S
Here, V1 is the titrant volume (mL) in the sample solution, V0 is the titrant volume (mL) in the blank solution, N is the titrant normality (N), f is the titrant factor, and S is the polyester resin. It is the mass (g) of the composition.

(3) Quantitative determination of alkali metal atoms (elements) in the polyester composition (unit: ppm)
Quantification was carried out by an atomic absorption method (manufactured by Hitachi Ltd.: polarized Zeeman atomic absorption spectrophotometer 180-80, frame: acetylene-air).

(4) Quantitative determination of Mn atoms (elements) and P atoms (elements) in the polyester composition (unit: ppm)
Quantification was performed using a fluorescent X-ray spectrometer (model number: 3270) manufactured by Rigaku Denki Co., Ltd.

(5) Measurement of particle content in polyester composition (unit: wt%)
30 g of the polyester composition was added to 300 mL of OCP, dissolved at 150° C. for 1 hour, and centrifuged at 18000 rpm and 20° C. for 1 hour. 300 mL of dichloromethane was added to the obtained solid content, and the mixture was centrifuged at 18000 rpm and 20° C. for 1 hour to obtain a solid content. 300 mL of dichloromethane was added again to the obtained solid content, and centrifugation was performed under the same conditions. This centrifugation with dichloromethane was performed a total of 3 times to remove the OCP. The obtained solid content was vacuum-dried (25° C., 1 hour), weighed, and the content was calculated from the weight value.
As a centrifuge, a himac CR20G (rotor: R19A) manufactured by HITACHI was used.
(6) Particle content (unit: wt%) measurement and amount of change in the polyester composition after heating and melting The polyester composition is pretreated at 150 ° C. for 3 hours and further vacuum dried at 180 ° C. for 7.5 hours, After heating and melting at 300° C. for 10 hours under nitrogen flow, it is quenched in water. The particle content of the resulting composition was calculated by the method (5) above.
Also, the amount of change is the ratio of the particle content after heating and melting obtained above to the particle content obtained in (5).

(7) Detection of P atoms (elements) on particle surfaces The polyester composition was dissolved in OCP by the method of (5) above and centrifuged. After drying the solid content, the content of P atoms (elements) was evaluated using SEM-EDX.

(8) Particle volume average diameter measurement in polyester composition (unit: μm)
The polyester composition was plasma-treated, and the volume-average diameter of the particles was measured using a Hitachi field emission scanning electron microscope (model number S-4000) and a Nideco SEM-IMAGEANALYZER (model number Ludex AP). In addition, when analyzing the particle size, measure at least 20 fields of view at a magnification of 5000 times, measure the circle equivalent diameter from at least 200 particles, consider it as a pseudo three-dimensional sphere, and calculate the volume average particle size. bottom.

(9) Evaluation of hydrolysis resistance of polyester composition (ΔCOOH/COOH) [hydrolysis resistance]
The polyester composition was subjected to wet heat treatment at 155° C. for 4 hours under saturated steam, and the amount of COOH terminal groups before and after the treatment was measured to calculate the increase in COOH terminal groups (ΔCOOH=COOH after treatment−COOH before treatment). Hydrolysis resistance was evaluated by dividing this value of ΔCOOH by the amount of COOH terminal groups before treatment.
The processor used was PRESSER COOKER 306SIII (manufactured by HIRAYAMA Seisakusho Co., Ltd.).

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

(11) Scattering amount of linear oligomer of polyester composition (unit: ppm)
The measurement sample was dried in a vacuum dryer at 150° C. for 3 hours and further at 180° C. for 7.5 hours, melted at 290° C. for 30 minutes under nitrogen flow, and then quenched in water to form chips. Further, the chip-shaped polymer was vacuum-dried at room temperature for 3 hours, 3 g of the chip-shaped polymer was placed in a crucible, an oligomer collection plate (petri dish) was placed on the crucible, and heat-treated in the air at 220°C for 8 hours. bottom. After adding 5 mL of DMF (N,N-dimethylformamide) to the petri dish to which the linear oligomer was attached and dissolving it, the absorbance was measured with a spectrophotometer (model number: U-3010, manufactured by HITACHI), and prepared from a standard solution. The linear oligomer scattering amount (ppm) with respect to the weight of the polyester composition was obtained from the calibration curve obtained.

(Example 1)
A slurry consisting of 86 parts by weight of terephthalic acid and 37 parts by weight of ethylene glycol (1.15 times the moles of terephthalic acid) was gradually added to an esterification reactor charged with 105 parts by weight of BHT melted at 250°C, Let the esterification reaction 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% to obtain BHT.
105 parts by weight (equivalent to 100 parts by weight of PET) of BHT was charged from the esterification reactor in a molten state to the polymerization apparatus, and the temperature was adjusted to 255°C. Ethylene glycol solution of manganese acetate tetrahydrate (23.5 ppm as Mn atom (element) relative to the weight of the polyester composition), ethylene glycol slurry of diantimony trioxide (Sb atom (element) relative to the weight of the polyester composition 255 ppm) was added. After that, 5 parts by weight of ethylene glycol (0.15 times the molar amount of the terephthalic component) was additionally added to proceed with depolymerization, and then phosphoric acid (18.8 ppm as P atom (element) with respect to the weight of the polyester composition) and phosphorus Ethylene glycol solution of sodium dihydrogen acid dihydrate (14 ppm as Na atom (element) and 18.9 ppm as P atom (element) with respect to the weight of the polyester composition) and ethylene glycol with a concentration of calcium carbonate particles of 20 wt% All slurries were mixed and stirred for 60 seconds to obtain a homogenous slurry and then added. (1 part by weight as calcium carbonate).
After that, the inside of the polymerization apparatus was gradually heated to 290° C., the pressure was reduced from normal pressure to 250 Pa or less, and the polymerization reaction was carried out at 290° C. until a predetermined stirring torque was exhibited. After completion of the polymerization reaction, the inside of the reaction system was brought to normal pressure with nitrogen gas, and the melted polyester in the polymerization apparatus was discharged into a water tank in the form of strands, cooled, and then cut to obtain a polyester composition in the form of pellets. Table 1 shows the properties of the resulting polyester composition.
The polyester composition obtained in Example 1 has good hydrolysis resistance and particle dispersibility, and has a small amount of linear oligomer scattering, so it has physical properties suitable for optical films and release films. .

(Examples 2-4, Comparative Examples 1-3)
A polyester composition was obtained in the same manner as in Example 1, except that the amount of the manganese compound added was changed as shown in Table 1. Table 1 shows the properties of the resulting polyester composition.
The polyester compositions obtained in Examples 2 to 4 have good hydrolysis resistance and particle dispersibility, and have a small amount of linear oligomer scattering, so they have physical properties suitable for optical films and release films. Was.
Since the polyester composition obtained in Comparative Example 1 did not contain a manganese compound, ΔCOOH/COOH was increased and was unsatisfactory.
The polyester composition obtained in Comparative Example 2 had an increased ΔCOOH/COOH ratio due to the small amount of manganese compound added, and was unacceptable.
Since the polyester composition obtained in Comparative Example 3 contained a large amount of the manganese compound, the scattering amount of the linear oligomer increased and was unacceptable.

(Examples 5 to 8, Comparative Examples 4 and 5)
A polyester composition was obtained in the same manner as in Example 1, except that the amount of the alkali metal phosphate, which is an alkali metal compound, was changed as shown in Table 2. Table 2 shows the properties of the resulting polyester composition.
The polyester compositions obtained in Examples 5 to 8 had good hydrolysis resistance and particle dispersibility, and the amount of linear oligomer scattering was at an acceptable level.
Since the polyester composition obtained in Comparative Example 4 did not contain an alkali metal, ΔCOOH/COOH and the amount of scattered linear oligomer increased.
Since the polyester composition obtained in Comparative Example 5 contained a large amount of alkali metal, ΔCOOH/COOH increased.

(Examples 9-11, 14-21)
A polyester composition was obtained in the same manner as in Example 1 except that the compound containing an Mn atom (element), the compound containing an alkali metal atom (element), the type of particles or the amount added were changed as shown in Table 3. . Table 3 shows the properties of the resulting polyester composition.
The polyester compositions obtained in Examples 9 to 11 and 18 to 23 had good hydrolysis resistance and particle dispersibility, and the scattering amount of linear oligomers was small.

(Example 12)
In the same manner as in Example 1, 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT was charged from the esterification reactor in a molten state to the polymerization apparatus, and the temperature was adjusted to 255°C. Ethylene glycol solution of manganese acetate tetrahydrate (23.5 ppm as Mn atom (element) relative to the weight of the polyester composition), ethylene glycol slurry of diantimony trioxide (255 ppm as Sb atom (element)), potassium hydroxide of ethylene glycol solution (14.0 ppm as K atom (element) relative to the weight of the polyester composition) was added. After that, 5 parts by weight of ethylene glycol (0.15 times the molar amount of the terephthalic component) was additionally added to proceed with depolymerization, and then phosphoric acid (18.8 ppm as P atom (element) with respect to the weight of the polyester composition) and phosphorus Ethylene glycol solution of sodium dihydrogen acid dihydrate (14 ppm as Na atom (element) and 18.9 ppm as P atom (element) with respect to the weight of the polyester composition) and ethylene glycol with a concentration of calcium carbonate particles of 20 wt% All slurries were mixed and stirred for 60 seconds to obtain a homogenous slurry and then added. (1 part by weight as calcium carbonate).
After that, the inside of the polymerization apparatus was gradually heated to 290° C., the pressure was reduced from normal pressure to 250 Pa or less, and the polymerization reaction was carried out at 290° C. until a predetermined stirring torque was exhibited. After completion of the polymerization reaction, the inside of the reaction system was brought to normal pressure with nitrogen gas, and the melted polyester in the polymerization apparatus was discharged into a water tank in the form of strands, cooled, and then cut to obtain a polyester composition in the form of pellets. Table 3 shows the properties of the resulting polyester composition.
The polyester composition obtained in Example 12 had good hydrolysis resistance and particle dispersibility, and the amount of linear oligomer scattering was small.

(Example 13)
In the same manner as in Example 1, 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT was charged from the esterification reactor in a molten state to the polymerization apparatus, and the temperature was adjusted to 255°C. Ethylene glycol solution of manganese acetate tetrahydrate (23.5 ppm as Mn atom (element) relative to the weight of the polyester composition), ethylene glycol slurry of diantimony trioxide (Sb atom (element) relative to the weight of the polyester composition 255 ppm as K), and an ethylene glycol solution of potassium hydroxide (14.0 ppm as K atom (element) with respect to the weight of the polyester composition). After that, 5 parts by weight of ethylene glycol (0.15 times the molar amount of the terephthalic component) was additionally added to proceed with depolymerization, and then phosphoric acid (18.8 ppm as P atom (element) with respect to the weight of the polyester composition) and phosphorus Ethylene glycol solution of sodium dihydrogen acid dihydrate (14 ppm as Na atom (element) and 18.9 ppm as P atom (element) with respect to the weight of the polyester composition) and ethylene glycol with a concentration of calcium carbonate particles of 20 wt% All slurries were mixed and stirred for 60 seconds to obtain a homogenous slurry and then added. (1 part by weight as calcium carbonate).
After that, the inside of the polymerization apparatus was gradually heated to 290° C., the pressure was reduced from normal pressure to 250 Pa or less, and the polymerization reaction was carried out at 290° C. until a predetermined stirring torque was exhibited. After completion of the polymerization reaction, the inside of the reaction system was brought to normal pressure with nitrogen gas, and the melted polyester in the polymerization apparatus was discharged into a water tank in the form of strands, cooled, and then cut to obtain a polyester composition in the form of pellets. Table 3 shows the properties of the resulting polyester composition.
The polyester composition obtained in Example 13 had good hydrolysis resistance and particle dispersibility, and the amount of linear oligomer scattering was small.

(Examples 22 to 29, Comparative Example 6)
A polyester composition was obtained in the same manner as in Example 1, except that the type or amount of the acidic compound was changed as shown in Table 4. Table 4 shows the properties of the resulting polyester composition.
The polyester compositions obtained in Examples 22 to 29 had good hydrolysis resistance and particle dispersibility, and the amount of linear oligomer scattering was small.
Since the polyester composition obtained in Comparative Example 6 did not contain an acidic compound, ΔCOOH/COOH increased and the amount of scattered linear oligomers increased, so it was disqualified.

(Example 30)
101.0 parts by weight of dimethyl terephthalate and 64.6 parts by weight of ethylene glycol (twice the molar amount of the dicarboxylic acid component) were weighed out and charged into a transesterification reactor. After dissolving the contents at 150 ° C., ethylene glycol solution of manganese acetate tetrahydrate (23.5 ppm as Mn atom (element) relative to the weight of the polyester composition), ethylene glycol slurry of diantimony trioxide (polyester composition 255 ppm as Sb atom (element) relative to the weight of the product) was added and stirred. Methanol was distilled off while the temperature was raised to 240° C., and the transesterification reaction was terminated when a predetermined amount of methanol was distilled off. Thereafter, the reactants were transferred to a polymerization apparatus, phosphoric acid (18.8 ppm as P atom (element) relative to the weight of the polyester composition) and sodium dihydrogen phosphate dihydrate (Na An ethylene glycol solution containing 14 ppm as an atom (element) and 18.9 ppm as a P atom (element)) and an ethylene glycol slurry having a concentration of calcium carbonate particles of 20 wt% are all mixed and stirred for 60 seconds to obtain a homogeneous slurry. was added. (1 part by weight as calcium carbonate). After the addition, the inside of the polymerization apparatus was gradually heated to 290° C., the pressure was reduced from normal pressure to 250 Pa or less, and the polymerization reaction was carried out at 290° C. until a predetermined stirring torque was exhibited. After completion of the polymerization reaction, the inside of the reaction system was brought to normal pressure with nitrogen gas, and the melted polyester in the polymerization apparatus was discharged into a water tank in the form of strands, cooled, and then cut to obtain a polyester composition in the form of pellets. Table 5 shows the properties of the resulting polyester composition.
The polyester composition obtained in Example 31 had good hydrolysis resistance and particle dispersibility, and the amount of linear oligomer scattering was small.

(Comparative Example 7)
In the same manner as in Example 1, 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT was charged from the esterification reactor in a molten state to the polymerization apparatus, and the temperature was adjusted to 255°C. Ethylene glycol solution of manganese acetate tetrahydrate (23.5 ppm as Mn atom (element) relative to the weight of the polyester composition), ethylene glycol slurry of diantimony trioxide (Sb atom (element) relative to the weight of the polyester composition 255 ppm) was added. Thereafter, 5 parts by weight of ethylene glycol (0.15 times the molar amount of the terephthalic component) was added to proceed with depolymerization, and then phosphoric acid (18.8 ppm as P atom (element) relative to the weight of the polyester composition) and phosphorus A mixed ethylene glycol solution of sodium dihydrogen acid dihydrate (14 ppm as Na atom (element) and 18.9 ppm as P atom (element) relative to the weight of the polyester composition) was added.
After that, the inside of the polymerization apparatus was gradually heated to 290° C., the pressure was reduced from normal pressure to 250 Pa or less, and the polymerization reaction was carried out at 290° C. until a predetermined stirring torque was exhibited. After completion of the polymerization reaction, the inside of the reaction system was brought to normal pressure with nitrogen gas, and the melted polyester in the polymerization apparatus was discharged into a water tank in the form of strands, cooled, and then cut to obtain a polyester composition in the form of pellets.
The obtained polyester composition was dissolved using a vented extruder, and an aqueous slurry containing calcium carbonate particles at a concentration of 20 wt % (1 part by weight as calcium carbonate) was added to the polyester composition and kneaded. After the kneading, the mixture was extruded into cold water through an extruder nozzle and cut into pellets to obtain a polyester composition. The resulting polyester composition had an increased amount of COOH terminal groups, an increased ΔCOOH/COOH ratio, and a large amount of scattered linear oligomers, and was unacceptable.

(Comparative Example 8)
In the same manner as in Example 1, 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT was charged from the esterification reactor in a molten state to the polymerization apparatus, and the temperature was adjusted to 255°C. Ethylene glycol solution of manganese acetate tetrahydrate (23.5 ppm as Mn atom (element) relative to the weight of the polyester composition), ethylene glycol slurry of diantimony trioxide (Sb atom (element) relative to the weight of the polyester composition 255 ppm) was added. Thereafter, 5 parts by weight of ethylene glycol (0.15 times the molar amount of the terephthalic component) was added to proceed with depolymerization, and then phosphoric acid (18.8 ppm as P atom (element) relative to the weight of the polyester composition) and phosphorus A mixed ethylene glycol solution of sodium dihydrogen acid dihydrate (14 ppm as Na atom (element) and 18.9 ppm as P atom (element) relative to the weight of the polyester composition) was added. After adding the phosphorus compound, an ethylene glycol slurry having a calcium carbonate particle concentration of 20 wt % was added (1 part by weight as calcium carbonate).
After that, the inside of the polymerization apparatus was gradually heated to 290° C., the pressure was reduced from normal pressure to 250 Pa or less, and the polymerization reaction was carried out at 290° C. until a predetermined stirring torque was exhibited. After completion of the polymerization reaction, the inside of the reaction system was brought to normal pressure with nitrogen gas, and the melted polyester in the polymerization apparatus was discharged into a water tank in the form of strands, cooled, and then cut to obtain a polyester composition in the form of pellets. The resulting polyester composition had a large amount of scattered linear oligomers and a large amount of particles in the polyester composition after being heated and melted.

Claims (2)

When producing a polyethylene terephthalate composition by subjecting a dicarboxylic acid or a dicarboxylic acid ester and a diol to an esterification reaction or a transesterification reaction, followed by a polycondensation reaction, a compound containing an Mn atom (element), a sodium phosphate metal salt or a phosphorus a potassium acid metal salt , an acidic compound containing P atoms (elements), and particles of at least one selected from the group consisting of calcium carbonate, silicon dioxide, titanium dioxide, and aluminum oxide having a volume average diameter of 3.0 μm or less, are polycondensed. A method for producing a polyethylene terephthalate composition, which is added before the end of the reaction, the added amount satisfies the formulas (V) and (VI), and the particles and the acidic compound are mixed and then added.
5 ppm ≤ Mn atom (element) addition amount (weight ratio to polyethylene terephthalate composition) ≤ 50 ppm (V)
5 ppm ≤ added amount of alkali metal atom (element) (weight ratio to polyethylene terephthalate composition) ≤ 100 ppm (VI) 2. The method for producing a polyethylene terephthalate composition according to claim 1 , wherein the particles and the acidic compound are mixed for 10 seconds or longer.