JPH03210358A - Polyester composition and production thereof - Google Patents

Abstract

PURPOSE:To obtain a polyester compsn. causing no filter jamming during molding and giving a film excellent in the slip, transparency, and abrasion resistance by mixing a slurry of a particulate crosslinked polymer having a specified particle diameter and functional groups with a polyester by a vent type extruder. CONSTITUTION:A polyester is prepd. from a dicarboxylic acid component mainly consisting of an arom. dicarboxylic acid (e.g. terephthalic acid) and at least one glycol component (e.g. diethylene glycol). Separately, a particle crosslinked polymer having a mean particle diameter of 0.01-5mum and functional groups (e.g. styrene-divinylbenzene copolymer) is dispersed in water and(or) an org. solvent having a b.p. of 200 deg.C or lower (e.g. methanol) to give a slurry. Then, the polyester and the slurry are fed to a vent type extruder and mixed therein to give a polyester compsn. wherein the particulate crosslinked polymer is contained in a uniform monodisperse state.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a polyester composition containing crosslinked polymer particles having an average particle size of 0.01 to 5 μm and having a functional group in a uniform monodisperse state. It relates to products and their manufacturing methods.

[Prior Art] Polyester, particularly polyethylene terephthalate, has excellent physical and chemical properties and is therefore widely used as fibers, films, and other molded products. However, contrary to its excellent properties, undesirable problems occur, such as poor workability due to poor process passability in the molding process to obtain the above-mentioned molded product, or poor slipperiness during handling of the product itself, and a decrease in product value. is also known.

To address these problems, many methods have been proposed to improve the slipperiness of the surface of molded products by adding fine particles to the surface of the molded product by incorporating fine particles into the polyester, and some of these methods have not yet been put into practical use. ing. For example, inert inorganic particles such as silicon oxide, titanium dioxide, calcium carbonate, talc, and kaolinite, or organic polymers such as benzoguanamine formaldehyde resin, polytetrafluoroethylene-hexafluoropropylene copolymer, and polyphenyl ester resin. There is a method of adding molecular fine particles to a polyester synthesis reaction system (for example, JP-A-55-133431, JP-A-57-125247, etc.).

However, the method of adding inert inorganic particles generally has poor affinity with polyester, and for example, when formed into a film, voids are generated around the particles. In addition, coarse particles are often mixed in, and even if pulverization and classification operations are performed to remove them, the contamination of coarse particles cannot be avoided. When voids are generated or coarse particles are present in this way,
For example, the transparency of films that require transparency, such as those used for plate making and printing or microfilm, is significantly reduced, and the electrical properties of capacitor films are adversely affected. Furthermore, in films for magnetic tapes, they degrade electromagnetic conversion characteristics and cause dropouts, impairing film quality.

On the other hand, the method of adding organic polymer fine particles generally has good affinity with polyester, but it is difficult to obtain uniform fine particles, and even if it is obtained, the dispersibility in the polyester is poor, such as agglomeration in the polyester. Therefore, the contamination of coarse particles cannot be avoided.

In recent years, higher quality is required for films that require transparency, capacitor films, magnetic tape films, etc., and films that are easy to slip, have a uniform surface, and contain particles that have excellent affinity with polyester. Film or desired. Therefore, the present inventors aimed to improve the drawbacks of the conventional particle addition method described above, and to obtain a polyester film that is particularly excellent in slipperiness, film surface uniformity, transparency, abrasion resistance, etc. As a result of extensive studies, it has been found that the object of the present invention can be achieved by using a polyester in which crosslinked polymer particles having functional groups are uniformly and monodispersed.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve problems that could not be achieved by conventional techniques because the crosslinked polymer particles are uniformly monodispersed in polyester and the crosslinked polymer particles have functional groups. An object of the present invention is to provide a polyester composition having excellent slip properties, surface uniformity, transparency, and abrasion resistance, and a method for producing the same.

[Means to solve the problem] The above-mentioned object of the present invention is achieved by the following configuration.

(1) Polyester consisting of a bifunctional acid component mainly consisting of an aromatic dicarboxylic acid and at least one type of glycol component is uniformly monodispersed into crosslinked polymer particles having an average particle size of 0.01 to 5 μm and having a functional group. A polyester composition comprising:

(2) In a vent-type molding machine, a slurry of water and/or an organic compound having a boiling point of 200°C or less of crosslinked polymer particles having an average particle size of 0.01 to 5 μm and having a functional group is added to the polyester. A method for producing a polyester composition.

The difunctional acid component of the polyester of the present invention is mainly an aromatic dicarboxylic acid or an ester-forming derivative thereof, and specifically, terephthalic acid, 2,6-naphthalene dicarboxylic acid 1,2-bis( chlorophenoxy)ethane-4-4-dicarboxylic acid, its ester-forming derivatives include dimethyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl 1,2-bis(chlorophenoxy)ethane-4,4-dicarboxylate, etc. Among them, terephthalic acid or dimethyl terephthalate is preferred.

In addition, examples of the glycol component include ethylene glycol, butylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, 1,4-cyclohexane dimetasil, and the like, with ethylene glycol being preferred. In addition to these dicarboxylic acids or their ester-forming derivatives and glycol components, other components may be copolymerized, such as diethylene glycol, propylene glycol, neopentyl glycol, polyalkylene glycol, p-xylylene glycol, 1.4-Cyclohexane dimetatool, 5-
Diol components such as sodium sulforesorcin, adipic acid, sebacic acid, phthalic acid isophthalic acid, 2,6-
Examples include dicarboxylic acid components such as naphthalene dicarboxylic acid and 5-sodium sulfoisophthalic acid, polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid.

When the dicarboxylic acid component is a dicarboxylic acid, it undergoes an esterification reaction with a glycol, and when it is a dicarboxylic acid ester, it undergoes a transesterification reaction with a glycol, followed by polycondensation at high temperature and reduced pressure to obtain a polyester.

Moreover, polycondensation can also be carried out using the prepolymer itself as a starting material.

The crosslinked polymer particles used in the present invention generally include a monovinyl compound (A) having only one aliphatic unsaturated bond in the molecule, and a crosslinking agent having two or more aliphatic unsaturated bonds in the molecule. Examples include copolymers with compound (B) having the following, but the present invention is not limited to these, and any crosslinked polymer particles that are insoluble and infusible may be used.

Examples of the compound (A) include aromatic monovinyl compounds such as styrene, α-methylstyrene, fluoromethinone, and vinylpyrine; vinyl cyanide compounds such as acrylonitrile and methacrylate; butyl acrylate;
Acrylic acid ester monomers such as 2-ethylhexyl acrylate 1, methyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, N,N'-dimethylaminoethyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl methacrylate, 2 -methacrylic acid ester monomers such as hydroxyethyl methacrylate-1, glycidyl methacrylate, N,N--dimethylaminoethyl methacrylate, mono- or dicarboxylic acids and dicarboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc. Amide monomers such as anhydrides, acrylamide, and methacrylamide can be used.

Among them, styrene, α-methylstyrene and p-methylstyrene are preferred. Examples of compound (B) include divinylbenzene compounds, I.limethylolpropane triacrylate, trimethylolpropane trimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, 1
．． Examples include polyhydric acrylates and methacrylates such as 3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

Among the above, it is particularly preferable to use divinylbenzene, ethylene glycol dimethacrylate, or trimethylolpropane trimethacrylate. Two or more of these compounds (A) and (B) can also be used in combination.

Preferred examples of the composition of the crosslinked polymer particles of the present invention include styrene-divinylbenzene copolymer, styrene-acrylonitrile divinylbenzene copolymer,
Examples include styrene-methyl methacrylate-divinylbenzene copolymer. Among them, styrene-divinylbenzene copolymer is particularly preferred in terms of heat resistance.

Furthermore, regarding the heat resistance of the crosslinked polymer particles of the present invention, particles having a thermal decomposition temperature (10% weight loss temperature) measured on a thermobalance of 380°C or higher are preferable, and more preferably 40°C or higher.
The temperature is 0°C or higher, particularly preferably 410°C or higher. 380
If the temperature is below 0.degree. C., particles tend to agglomerate during melt molding during production of the polyester composition or during recovery and reuse of the molded article, impairing the surface uniformity, abrasion resistance, etc. of the molded article. In order to have such heat resistance, it is necessary to highly crosslink the compound (B) with a crosslinking agent. There is no particular limitation on the type of crosslinking agent, but divinylbenzene is preferred among them, and it is necessary to use 12% by weight or more of pure divinylbenzene based on the monomer, preferably 35% by weight or more, and more preferably 5% by weight or more.
It is 5% by weight or more.

The crosslinked polymer particles used in the present invention have easy sliding properties, surface uniformity,
From the viewpoint of transparency, particles with a spherical shape and a uniform particle size distribution are preferable.

That is, it is preferable that the volume shape factor is 0.35 to 0.52, and more preferably 0.45 or more. [
However, the volumetric shape factor f is expressed by the following equation. f=V/
D3, where ■ is the particle volume (μm3), and D is the maximum diameter of the particle in the projected plane (μm)] As the crosslinked polymer particles of the present invention, those obtained by known manufacturing methods can be used. Known manufacturing methods include the following methods, for example, by emulsion polymerization.

(1) Soap-free polymerization method, that is, a method in which polymerization is performed without using an emulsifier or with a very small amount of emulsifier.

(2) A seed polymerization method in which polymer particles are added to the polymerization system prior to emulsion polymerization and emulsion polymerization is carried out.

(3) A core-shell polymerization method in which a part of the monomer components is emulsion polymerized and the remaining monomers are polymerized within the polymerization system.

(4) Polymerization methods using Nigelstad et al., as disclosed in JP-A-54-97582 and JP-A-54-126288.

(5) A polymerization method that does not use a swelling aid in the method of (4).

Among the above methods, methods (3) and (4) are particularly preferred because they can yield spherical crosslinked polymer particles having a uniform particle size distribution.

In the present invention, it is necessary that the crosslinked polymer particles have a functional group. That is, a functional group that improves affinity with polyester is required.

There are no particular limitations on the type of such functional groups, but examples include carboxyl groups, hydroxyl groups, sulfonic acid groups, and ester groups. Among these, metal salts thereof are preferred because they improve affinity with polyester, and metal salts of carboxyl groups are particularly preferred. Furthermore, there is no particular limitation on the method of introducing the functional group, but from the viewpoint of the heat resistance of the particles, it is preferable to produce particles that will become a base for -degree hypercrosslinking and introduce the functional group onto the surface of the base particle. For example, when introducing a sodium salt of a carboxyl group, a styrene-divinylbenzene copolymer is used as the base particle to produce particles that are highly crosslinked with divinylbenzene, and then a carboxyl group is introduced onto the particle surface using methacrylic acid.

By setting the inside of the particle production system to the alkaline side, the -COONa functional group is introduced onto the particle surface.

The amount of monomer for introducing these functional groups is preferably 0.01 to 20% by weight, and 0.1 to 10% by weight based on the base particle.
% by weight is more preferred.

In the present invention, the average particle diameter of the crosslinked polymer particles dispersed in the polyester must be 0.01 to 5 μm, more preferably 0.05 to 2 μm. If the average particle size is less than 0.01 μm, the slipperiness will be reduced when formed into a film.

Furthermore, if the average particle size exceeds 5 μm, the transparency will deteriorate due to increased scattering on the film surface due to coarse protrusions, or the abrasion resistance will become poor.

Further, the amount of crosslinked polymer particles added to the polyester is preferably 0.0001 to 20% by weight, more preferably 0.001 to 10% by weight, and even more preferably 0.
．． 01 to 5% by weight.

In the present invention, it is necessary to uniformly and monodisperse crosslinked polymer particles in polyester. In the present invention, "uniform monodisperse" refers to a state in which there are almost no secondary agglomerated particles and they are dispersed as missing particles in the polymer. That is, when observing the polymer using a transmission electron microscope, it is preferable that the number of secondary agglomerated particles per 0.01 mm2 field of view is 20 or less. More preferably, the number is 15 or less, and still more preferably 10 or less.

The crosslinked polymer particles of the present invention can be incorporated into the polymer by various known methods, such as adding to and mixing with a polyester synthesis reaction system. A method in which a slurry of an organic compound with a boiling point of 200°C or less is added, water and/or an organic compound with a boiling point of 200°C or less are removed under heating and reduced pressure, and melt-kneaded is more uniform and monodispersed. preferable. The vent molding machine is a melt molding machine provided with at least one vent hole, and may be, for example, an extrusion molding machine or an injection molding machine. At least one of the vent holes for removing water and/or organic compounds with a boiling point of 200° C. or less must be maintained under reduced pressure. Further, the degree of pressure reduction in the vent hole is preferably maintained at 100 Torr or less, more preferably 50 Torr or less, and even more preferably 30 Torr or less.

On the other hand, the crosslinked polymer particles must be added to the polyester as a slurry of water and/or an organic compound having a boiling point of 200° C. or less. Examples of organic compounds with a boiling point of 200°C or lower include alcohols such as alcohol, ethanol, and ethylene glycol, hydrocarbon compounds such as benzene and toluene, and others such as esters, ketones, and amines, but are not particularly limited. . Among these, water is preferred from the viewpoint of handling properties, removability, etc. Of course, a mixed solvent of two or more types of water and/or organic compounds may be used, and in that case, a water-rich mixed solvent is preferred.

In addition, in the slurry of the crosslinked polymer particles, anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, which are necessary for the particle manufacturing method, and nonionic surfactants such as polyoxyethylene nonylphenyl ether and polyethylene glycol monostearate are added. surfactant,
It is preferable to include a protective agent such as polyvinyl alcohol or carboxymethylcellulose from the viewpoint of particle dispersibility.

Furthermore, the water and/or boiling point of the crosslinked polymer particles is 200°C.
The following organic compound slurry concentrations are not particularly limited, but
The amount of water and/or organic compound having a boiling point of 200° C. or lower relative to the polymer is preferably 2% by weight or more and 30% by weight or less. More preferably, it is 2% by weight or more and 20% by weight or less. If the amount is less than 2% by weight, the dispersibility in the polymer tends to deteriorate, which is not preferable. If it exceeds 30% by weight, the intrinsic viscosity of the polymer tends to decrease, which is not preferable.

By using the method of the present invention, polyester can be made to contain crosslinked polymer particles at a high concentration.

Therefore, it is also possible to produce a polyester containing a high concentration of crosslinked polymer particles, dilute it with a polyester substantially free of particles, and use it.

According to this method, it is possible to add and mix crosslinked polymer particles to polyester in the form of a slurry of water and/or an organic compound having a boiling point of 200° C. or less. For example, when added at the time of polyester synthesis reaction, it is possible to avoid adverse effects such as significant delay of polyester synthesis reaction due to moisture or surfactant, and improve workability.

Furthermore, even crosslinked polymer particles with relatively poor heat resistance can be mixed with polyester.

In the present invention, the crosslinked polymer particles in the polymer are uniformly monodispersed, so when a stretched film is made, a uniform uneven surface can be obtained. Since the compatibility is good, a film having good lubricity, transparency, and abrasion resistance can be obtained.

Furthermore, the polyester of the present invention contains a metal compound catalyst such as lithium, sodium, calcium, magnesium, manganese, zinc, antimony, germanium, titanium, etc., which are commonly used in the production of polyester, a phosphorus compound as a coloring inhibitor, and a crosslinking agent. It may also contain inert particles other than polymer particles.

[Example] The present invention will be described in detail by giving examples below. In addition,
Each characteristic value of the obtained polyester was measured according to the following method.

(A) Particle size The average particle size was determined by electron micrographs of the particles.
It was determined by the particle equivalent spherical diameter corresponding to the volume % point. The equivalent spherical diameter is the diameter of a sphere with the same volume as the particle.

(B) Intrinsic viscosity of polymer Measured at 25°C using 0-chlorophenol as a solvent.

(C) Particle thermal decomposition temperature Rigaku Denki TAS-100 under nitrogen atmosphere, heating rate 2
A thermobalance weight loss curve at 0° C./min was measured. 10% was taken as the thermal decomposition temperature.

(D) State of dispersion of particles in polymer After cutting the polymer into ultra-thin sections of around 0°3 μm using an ultra-thin film production device, the state of dispersion of particles in the polymer was observed using a transmission electron microscope. The number of secondary agglomerated particles was counted.

(E) Film properties (1) Surface roughness Ra (μm) Measured using a stylus type surface roughness meter in accordance with J T5-B-0601 (cutoff value 0.08 mm, measurement length 4
mm).

(2) Slip property (μ and μs1μd) (a) μ Slit the film into 1/2 inch pieces Tape runability tester TBT-30 Type 0 (manufactured by Yokohama System Research Institute Co., Ltd.) 20℃, 60%RH atmosphere The initial μk is calculated using the following formula. I asked for it.

μ=0.7331og (TI/T2) where T2
is the inlet tension, and T1 is the outlet tension. The guide diameter is 6mmφ, the guide material is 5US27 (surface roughness 0°2S), and the winding angle is 18mm.
00, the running speed is 3.3 cm/sec.

The above μk is 0.35 or less has good slipperiness. Here, μk 0.35 is during film processing or manufacturing. The slipperiness when used as a product is extremely poor. This is the critical value for determining whether the

(b) μS1μd ASTM-D-1894B-63 Therefore, use a slip tester to Friction coefficient (μS) and dynamic friction coefficient (μd) was measured.

(3) Film haze According to ASTM-D1003-52 It was measured.

Note that slipperiness (μs): 0.7 or less and film haze: 0.55% or less are values that achieve the object of the present invention.

(4) Using a wear-resistant tape running tester TBT-300 (manufactured by Yokohama System Research Institute Co., Ltd.), at 25°C,
After repeatedly traveling 2000 times in an atmosphere of 0RH, white scraping powder (white powder) adhering to the guide portion was visually determined.

Here, the guide diameter is 8 mmφ, and the guide material is 5U.
S27 (Surface roughness 0.2S), wrapping angle is 180°
, the tape running speed is 3.3 cm/sec. The evaluation criteria are as follows.

◎: The amount of white powder generated is very small and the purpose is achieved.

○: The amount of white powder generated is small and the purpose is achieved.

△: The amount of white powder generated is slightly large, and the purpose is not met. not achieved.

×: The amount of white powder generated is very large, and the purpose not achieved.

Example 1 One-note chips of undried polyethylene terephthalate with an intrinsic viscosity of 0.615 containing 0.4% by weight of water were melted using a vented twin-screw extruder, and the polymer chips were melted into the final polymer. content 0. The average particle size is 0.5% by weight. An aqueous slurry of styrene-divinylbenzene copolymer particles (volume shape factor: 0.51) having a diameter of 3 .mu.m and having a sodium salt of a carboxyl group as a functional group (2% by weight relative to the polyfluoride) was added. Ventro I
The resin was melt-extruded at a resin temperature of 280° C. while maintaining the vacuum degree of QTorr to obtain polyethylene terephthalate containing styrene-divinylbenzene copolymer particles.

The intrinsic viscosity of the obtained polymer was 0.602, and a polymer was obtained in which the decrease in intrinsic viscosity was extremely small.

As a result of observing the polymer with a transmission electron microscope, it was found that 0
．． The number of secondary agglomerates per 01 mm2 field of view was 6 and existed in a substantially uniform monodisperse state.

The polymer was melt-extruded at 290° C., wound around a casting drum with a surface temperature of 30° C. using an electrostatic casting method, and cooled and solidified to obtain an unstretched film with a thickness of about 150 μm. This unstretched film was stretched 3.4 times in the longitudinal direction at 90°C and 3.6 times in the transverse direction at 100°C. Thereafter, it was heat-set at 210°C to obtain a biaxially stretched film with a thickness of 15 μm. As a result of evaluating the film properties, flatness,
Both slipperiness and abrasion resistance were good (Table 1).

Examples 2 to 5, Comparative Example 1.2 Containing crosslinked polymer particles (all with a volume shape factor of 0.
Polyethylene terephthalate was obtained using a vented extruder in the same manner as in Example 1, except that the particle composition, type of functional group, and average particle size of 51) were changed. The particles were dispersed in the polymer in a monodisperse state with little secondary aggregation. The polymer was made into a biaxially oriented film in the same manner as in Example 1. Containing crosslinked polymer particles whose particle composition, type of functional group, and average particle size were within the range of the present invention were excellent in flatness, slipperiness, and abrasion resistance when made into a film (Example) 2~
5).

However, if the crosslinked polymer particles have no functional groups or have an average particle size outside the scope of the present invention, when made into a film, flatness,
It was not possible to satisfy both slipperiness and abrasion resistance (Comparative Example 1.2).

Comparative Example 3 Polyethylene terephthalate was obtained using a vented extruder in the same manner as in Example 1, using wet silica powder as the particles contained. The polymer was made into a biaxially stretched film in the same manner as in Example 1. Since the contained particle species were other than those of the present invention, when made into a film, it was not possible to satisfy all flatness, slipperiness, and abrasion resistance.

Example 6 Using the same method as in Example 1 using a vented extruder, the average particle size was 0. Polyethylene terephthalate having a diameter of 6 μm and containing 2% by weight of styrene-divinylbenzene copolymer particles having a sodium salt of a carboxyl group as a functional group was obtained. As a result of observing the polymer using a transmission electron microscope, the number of secondary agglomerates per 0.01 mm2 field of view was 14, which was found to exist in a substantially uniform monodisperse state. The obtained polymer was adjusted to contain 0.05% by weight of styrene-divinylbenzene copolymer particles using a polymer containing no particles, and a biaxially oriented film was prepared from the polymer in the same manner as in Example 1. I got it. As a result of evaluating the film properties, it was found to be excellent in both transparency and slipperiness.

Example 7.8 Comparative Example 4 Containing crosslinked polymer particles (all with a volume shape factor of 0.
Polyethylene terephthalate containing 2% by weight was obtained in the same manner as in Example 5 by changing the particle composition, type of functional group, and average particle size of 51). The particles were dispersed in the polymer in a nearly uniform monodisperse state with little secondary aggregation. A biaxially oriented film was obtained from the polymer in the same manner as in Example 5. If the particle composition, type of functional group, and average particle size of the crosslinked polymer particles contained are within the range of the present invention, when made into a film,
Both transparency and slipperiness were excellent (Example 7.8).

However, when crosslinked polymer particles do not have functional groups, it was not possible to satisfy both transparency and slipperiness when made into a film (Comparative Example 4) Comparative Example 5 Polyethylene terephthalate with an intrinsic viscosity of 0.620 It was dried under reduced pressure at a temperature of 180°C. The chips and 2% by weight of styrene-acrylonitrile-divinylbenzene copolymer particles having an average particle size of 0.6 μm and having a sodium salt of a carboxyl group as a functional group were blended using an extruder, and the styrene-acrylonitrile-divinylbenzene copolymer powder was mixed with the powder using an extruder. Polyethylene terephthalate containing polymer particles was obtained. The state of particle dispersion in the polymer was very poor, and most of the particles were agglomerated. The obtained polymer was made into a biaxially oriented film in the same manner as in Example 5. The surface of the obtained film contained many coarse particles, and both transparency and slipperiness could not be satisfied.

(Left below) [Effects of the Invention] The polyester composition of the present invention is uniformly monodispersed in the polymer and contains crosslinked polymer particles having functional groups, so it exhibits the following excellent effects. .

(1) In the present invention, crosslinked polymer particles having functional groups are uniformly and monodispersed in polyester, so when making a film, for example, there is no clogging of the filter during the melt molding process, and the film is formed by coarse particles. There are no tears etc.

(2) In the present invention, since the crosslinked polymer particles are uniformly monodispersed in the polyester, a uniform uneven surface can be obtained when the film is made into a stretched film. In addition, crosslinked polymer particles have good affinity with polyester, but in the present invention, since the crosslinked polymer particles have functional groups, the affinity is further improved, resulting in significantly improved slipperiness, transparency, and abrasion resistance. Becomes good. Such films are suitable for magnetic tape applications, photography, plate-making applications, capacitor applications, and the like.

Claims (2)

[Claims] (1) Polyester consisting of a bifunctional acid component mainly consisting of an aromatic dicarboxylic acid and at least one type of glycol component is uniformly monodispersed into crosslinked polymer particles having an average particle size of 0.01 to 5 μm and having a functional group. A polyester composition comprising: (2) In a vent-type molding machine, a slurry of water and/or an organic compound having a boiling point of 200°C or less of crosslinked polymer particles having an average particle size of 0.01 to 5 μm and having a functional group is added to the polyester. A method for producing a polyester composition.