JP2643513B2 - Polyester composition, method for producing the same, and film comprising the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyester composition containing uniform monodisperse crosslinked polymer particles having an average particle diameter of two specific components and a method for producing the same.

[Prior art] Polyester, especially polyethylene terephthalate,
Due to its excellent physical and chemical properties, it is widely used as fibers, films and other molded products. However, contrary to the excellent characteristics, undesirable troubles such as deterioration in workability due to poor processability in the molding process for obtaining the molded product or poor slipperiness in handling of the product itself and reduction in product value occur. It is also known.

In order to solve these problems, a number of methods have been proposed to improve the slipperiness of the surface of the molded article by imparting moderate irregularities to the surface of the molded article by containing fine particles in the polyester,
Some of them have been put to practical use. For example, inert inorganic particles such as silicon oxide, titanium dioxide, calcium carbonate, talc, and kaolinite; or organic high inorganic materials such as benzoguanamine / formaldehyde resin, polytetrafluoroethylene-hexafluoropropylene copolymer, and polyphenylester resin. There is a method of adding molecular fine particles to a polyester synthesis reaction system (for example, JP-A-55-133431, JP-A-55-125247, etc.).

However, the method of adding inert inorganic particles generally has poor affinity with polyester. For example, when a film is formed, voids are generated around the particles. Also, coarse particles are often mixed in, and even if crushing and classifying operations are performed to remove these, mixing of coarse particles is still unavoidable. Thus, when voids are formed or coarse particles are present, for example, transparency is significantly reduced in plate making printing and microfilms, and adversely affects electrical characteristics in capacitor films. Furthermore, in the magnetic tape film, the electromagnetic conversion characteristics are reduced,
This can cause dropouts and impair film quality.

Further, JP-A-59-217755, JP-A-61-174254, and JP-A-1-104934 disclose a method using a crosslinked polymer particle having a sharp particle size distribution, or a method of distributing the surface protrusion distribution of a film. Although a regulation method has been proposed, the use of such particles or the method inevitably generates voids in the polyester, which is insufficient for applications requiring high transparency and abrasion resistance. Was. Japanese Patent Application Laid-Open No. 1-129038 proposes a film containing spherical cross-linked polystyrene particles. However, in this case, the mere use of a cross-linked polystyrene composition results in insufficient particle dispersibility in the polymer. Was not satisfactory in terms of uniformity. Further, JP-A-48-10177
In order to achieve both transparency and slipperiness,
Calcium carbonate on at least one side of the low haze film,
A film in which a layer containing fine inert inorganic compound particles such as silicon dioxide and a metal salt of terephthalic acid is laminated has been proposed, but achieves both high slipperiness and surface uniformity aimed at by the present invention. Was not enough.

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 obtained, poor dispersibility in polyester such as aggregation in polyester. Therefore, mixing of coarse particles is inevitable.

In recent years, higher quality is required for films requiring transparency, films for capacitors, films for magnetic tape, etc., and the film surface is uniform with smoothness,
A film containing particles having excellent affinity for polyester is desired.

Therefore, the present inventors have intensively studied to improve the drawbacks of the above-mentioned conventionally used particle addition method, and to obtain a polyester film having excellent smoothness and uniformity of the film surface, especially abrasion resistance. It has been found that the object of the present invention can be achieved by using a polyester in which crosslinked polymer particles having an average particle diameter of two specific components are uniformly and monodispersed in the polyester.

[Problems to be Solved by the Invention] An object of the present invention is to provide a crosslinked polymer particle having an average particle diameter of two specific components that is uniformly and monodispersed in a polyester, so that the slipperiness which cannot be achieved by the prior art is achieved. Properties, surface uniformity,
And to provide a polyester composition having excellent abrasion resistance.

Another object of the present invention is to provide a method for easily and uniformly dispersing the above-mentioned two-component crosslinked polymer in polyester.

[Means for Solving the Problems] The object of the present invention can be achieved by the following configuration.

(1) Crosslinked polymer particles (a) having an average particle diameter of 0.01 μm or more and less than 0.1 μm (a) (hereinafter referred to as “first”) are obtained by adding a bifunctional acid component mainly composed of an aromatic dicarboxylic acid to a polyester comprising at least one glycol component. Component)) and average particle size
0.1 to 5 μm crosslinked polymer particles (b) (hereinafter also referred to as a second component) are contained in a uniform monodispersed state, and the crosslinked polymer particles (a) and the crosslinked polymer particles (b) as a whole Ratio Dw between weight average diameter Dw and number average diameter Dn in particle size distribution
The polyester composition, wherein / Dn is 1.3 to 10.

(2) In molding the above polyester composition, the polyester has an average particle size of 0.01 μm in a vent type molding machine.
crosslinked polymer having an average particle diameter of 0.1 to 5
A process for producing a polyester composition, comprising adding water of a μm crosslinked polymer particle and / or an organic compound slurry having a boiling point of 200 ° C. or less, followed by molding.

The bifunctional acid component of the polyester of the present invention is mainly composed of an aromatic carboxylic 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, dimethyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl 1,2-bis (chlorophenoxy) ethane-4,4-dicarboxylate as ester-forming derivatives thereof Among them, terephthalic acid or dimethyl terephthalate is preferable.

In addition, ethylene glycol as a glycol component,
Examples thereof include butylene glycol, diethylene glycol, propylene glycol, polyethylene gnochol, and 1,4-cyclohexanedimethanol. Among them, ethylene glycol is preferable.

In addition to these dicarboxylic acids or their ester-forming derivatives and glycol components, other components may be copolymerized, such as dimethylene glycol, propylene glycol, neopentyl glycol, polyalkylene glycol, p-xylylene glycol. , 1,4-
Diol components such as cyclohexane dimethanol and 5-sodium sulforesorcin, adipic acid, sebacic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid,
-A dicarboxylic acid component such as sodium sulfoisophthalic acid; a polyfunctional dicarboxylic acid component such as trimellitic acid and pyromellitic acid; and an oxycarboxylic acid component such as p-oxyethoxybenzoic acid.

When the dicarboxylic acid component is a dicarboxylic acid, it is subjected to an esterification reaction with glycol, and when the dicarboxylic acid ester is a dicarboxylic acid ester, after a transesterification reaction with glycol, polycondensation is carried out at a high temperature under reduced pressure to obtain a polyester.

In addition, polycondensation can also be performed using the odor of the prepolymer as a starting material.

As the polyester obtained from such a monomer, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferred, and polyethylene-2,6-naphthalate is particularly preferred for applications requiring high rigidity.

The crosslinked polymer particles used in the present invention generally include a monovinyl compound (A) having only one aliphatic unsaturated bond in a molecule and two or more aliphatic unsaturated bonds in a molecule as a crosslinking agent. And a copolymer with the compound (B) having the following, but is not limited thereto, and may be insoluble,
Any insoluble crosslinked polymer particles may be used.

Examples of the compound (A) include aromatic monovinyl compounds such as styrene, α-methylstyrene, fluorostyrene, ethylvinylbenzene and vinylpyrine, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, butyl acrylate, 2-ethylhexyl Acrylate, methyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, acrylate monomer such as N, N'-dimethylaminoethyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, N,
Methacrylic acid ester monomers such as N'-dimethylaminoethyl methacrylate, acrylic acid, methacrylic acid, maleic acid, anhydrides of mono- or dicarboxylic acids and carboxylic acids such as itaconic acid, acrylamide,
Amide monomers such as methacrylamide can be used. Among them, styrene, α-methylstyrene and p-methylstyrene are preferred.

Examples of the compound (B) include a divinylbenzene compound or trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, or polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, 1,3 Polyhydric acrylates and methacrylates, such as -butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate. Among them, especially divinylbenzene,
Preference is given to using ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate.

These compounds (A) and (B) may be used as a mixture of two or more kinds.

Preferred examples of the composition of the crosslinked polymer particles of the present invention include a styrene-divinylbenzene copolymer, an ethylvinylbenzene-divinylbenzene copolymer, a styrene-acrylonitrile-divinylbenzene copolymer,
Those having divinylbenzene as a constituent component, such as styrene-methyl methacrylate-divinylbenzene copolymer, may be mentioned. Among them, a styrene-divinylbenzene copolymer and an ethylvinylbenzene-divinylbenzene copolymer are particularly preferable from the viewpoint of heat resistance. Here, for example, commercially available divinylbenzene or the like has a purity of about 55% (ethylvinylbenzene is included as a main impurity). Therefore, even when particles are synthesized only from commercially available divinylbenzene, the ethylvinylbenzene contained therein corresponds to the monovinyl compound (A), and divinylbenzene corresponds to the divinyl compound (B). Is obtained. Particularly preferred is heat resistance.

Further, with respect to the heat resistance of the crosslinked polymer particles of the present invention, particles having a heat resistance of 380 ° C. or higher, preferably a thermal decomposition temperature (10% weight loss temperature) by a thermobalance, more preferably 400 ° C.
° C or higher, particularly preferably 410 ° C or higher. If the temperature is lower than 380 ° C., particles tend to agglomerate during the production of the polyester composition, at the time of melt molding or at the time of collecting and reusing the molded product, and the surface uniformity and wear resistance of the molded product tend to be alienated. In order to have such heat resistance, it is necessary to highly crosslink with a crosslinking agent of the compound (B).

The type of the cross-linking agent is not particularly limited. Among them, divinylbenzene is preferable, and 12% by weight or more of pure divinylbenzene is required based on the monomer, preferably 35% by weight or more, and more preferably 55% by weight.

The crosslinked polymer particles used in the present invention preferably have a spherical particle shape and a uniform particle size distribution in terms of lubricity, surface uniformity, abrasion resistance and the like.

That is, those having a volume shape factor of 0.35 to 0.52 are preferable, and those having a volume shape factor of 0.45 or more are more preferable. [However, the volume shape factor f is represented by the following equation. f = V / D ³ , where V
Indicates the particle volume (μm ³ ), and D indicates the maximum diameter (μm) of the particle on the projection surface. As the crosslinked polymer particles of the present invention, those obtained by a known production method can be used. Known production methods include, for example, the following method by emulsion polymerization.

A soap-free polymerization method, that is, a method in which no emulsifier is used or polymerization is performed using an extremely small amount of an emulsifier.

A seed polymerization method in which polymer particles are added to a polymerization system prior to emulsion polymerization and emulsion polymerization is performed.

A core-shell polymerization method in which a part of the monomer component is emulsion-polymerized and the remaining monomer is polymerized in the polymerization system.

JP-A-54-97582 and JP-A-54-126288
Polymerization method using Yule gel stat and the like described in Japanese Patent Application Publication No.

 The polymerization method without using a swelling aid in the method of the above.

Of the above, the method and method are particularly preferred because spherical crosslinked polymer particles having a uniform particle size distribution can be obtained.

In the present invention, the crosslinked polymer particles dispersed and contained in the polyester have an average particle size of 0.01 μm or more and 0.1 μm or more, respectively.
There are two types: those having a particle diameter of less than μm, preferably 0.01 μm or more and less than 0.08 μm, more preferably 0.02 μm or more and less than 0.06 μm, and those having an average particle diameter of 0.1-5 μm, preferably 0.1-2 μm.

As the first component, the average particle size of the crosslinked polymer particles is 0.01 μm.
If it is less than m, the effect of improving the slipperiness becomes insufficient, which is not preferable. On the other hand, when the thickness is 0.1 μm or more, the surface flatness becomes insufficient, which is not preferable. On the other hand, if the average particle size of the crosslinked polymer particles as the second component exceeds 5 μm, the surface flatness and the shaving property become insufficient, which is not preferable.

When the crosslinked polymer particles composed of two components are dispersed and contained in the polyester, the ratio of the weight average diameter D _W to the number average diameter D _N , the value of D _W / D _N needs to be 1.3 or more and 10 or less. And preferably 1.3 or more and 5 or less.

When the crosslinked polymer particles composed of two components of the present invention are dispersed and contained in the polyester, the particles obtained by separately producing two kinds of crosslinked polymer particles may be mixed and dispersed and contained in the polyester. However, from the viewpoints of workability, cost, and surface flatness, it is preferable that two kinds of particles are simultaneously produced by the production of crosslinked polymer particles and dispersed and contained in the polyester.

In the present invention, the added amount of the crosslinked polymer particles as the second component is 0.0001 to 20% by weight, more preferably 0.001 to 10% by weight, and still more preferably 0.01 to 5% by weight based on the polyester. The amount of the crosslinked polymer particles as the first component is 0.01 to 5% by weight, more preferably 0.01 to 3% by weight, based on the crosslinked polymer particles of the second component.
And more preferably 0.05 to 2% by weight.

Further, in order to further improve the affinity with the polyester, the crosslinked polymer particles preferably have a functional group. In this case, the two types of particles may have a functional group on either or one of them, but among them, the particles having an average particle diameter of 0.1 to 5 μm as the second component have a functional group. This is preferable because the shaving property is improved.

The type of the functional group is not particularly limited, and examples thereof include a carboxyl group, a hydroxyl group, a sulfonic acid group, and an ester group. Above all, those metal salts are preferable because affinity with the polyester is improved, and a metal salt of a carboxyl group is particularly preferable.

Further, from the viewpoint of the heat resistance of the particles, it is preferable to once produce particles that become a highly crosslinked base, and to introduce a functional group to the surface of the base particles. The amount of the monomer for introducing these functional groups is preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight, based on the base particles.

In the present invention, the crosslinked polymer particles need to be monodispersed in the polyester. The term “monodisperse” as used in the present invention refers to a state in which there are almost no secondary aggregated particles and the particles are dispersed as primary particles in a polymer. That is, when the polymer is observed with a transmission electron microscope, the number of secondary aggregated particles per visual field of 0.01 mm ² is preferably 30 or less. The number is more preferably 25 or less, and further preferably 15 or less.

The crosslinked polymer particles of the present invention can be contained in the polymer by various known methods, for example, a method of adding to a polyester synthesis reaction system, mixing, and the like. A method in which water and / or an organic compound slurry having a boiling point of 200 ° C. or less of the crosslinked polymer particles of the second component is added, and water and / or an organic compound having a boiling point of 200 ° C. are removed under heating and reduced pressure, followed by melt-kneading. Is preferred.

The vent type 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 having a boiling point of 200 ° C. or lower must be kept under reduced pressure. Further, the degree of pressure reduction of the vent hole is preferably maintained at 100 Torr or less, and 50 Torr or less.
Or less, more preferably 30 Torr or less.

On the other hand, the crosslinked polymer particles have water and / or a boiling point of 200
It is necessary to add to the polyester as a slurry of an organic compound having a temperature of not more than ° C. Examples of the organic compound having a boiling point of 200 ° C. or lower include alcohols such as methanol, ethanol, and ethylene glycol, hydrocarbon compounds such as benzene and toluene, and esters, ketones, and amines as other compounds. Not done. Among them, water is preferred from the viewpoint of handling properties, removability and the like. Of course, water and / or the organic compound may be a mixed solvent of two or more kinds, and in that case, a water-rich mixed solvent is preferable.

In addition, in the slurry of crosslinked polymer particles, anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, nonionics such as polyoxyethylene nonylphenyl ether and polyethylene glycol monostearate necessary for the particle manufacturing method are contained. It is preferable to include a protective agent such as a system interface lubricant, polyvinyl alcohol, and carboxymethyl cellulose from the viewpoint of particle dispersibility.

Further, the water and / or boiling point of the crosslinked polymer particles
The concentration of the organic compound slurry at a temperature of not more than 0 ° C. is not particularly limited, but the amount of water and / or the organic compound having a boiling point of not more than 200 ° C. to the polymer is preferably from 2% by weight to 30% by weight. More preferably, the content is 2% by weight or more and 20% by weight or less. If it is less than 2% by weight, the dispersibility in the polymer tends to deteriorate, which is not preferred. 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, the crosslinked polymer particles can be contained in the polyester at a high concentration. Therefore, to produce a polyester containing a high concentration of crosslinked polymer particles,
It can also be used after being diluted with a substantially particle-free polyester.

According to this method, it is possible to add and mix the crosslinked polymer particles to the polyester in the form of water and / or an organic compound slurry having a boiling point of 200 ° C. or lower. For example, when it is added during the polyester synthesis reaction, when the polyester synthesis reaction is remarkably alienated by moisture or an interfacial lubricant, its adverse effect can be avoided and workability is improved. Further, crosslinked polymer particles having relatively low heat resistance can be mixed with the polyester.

In the present invention, the crosslinked polymer particles in the polymer are uniformly monodispersed. Therefore, when the film is formed into a stretched film, a uniform uneven surface is obtained. A film having both slipperiness and abrasion resistance can be obtained because of the composition.

Further, the polyester of the present invention includes a metal compound catalyst such as lithium, sodium, calcium, magnesium, manganese, zinc, antimony, germanium, titanium, or the like, which is generally used in the production of the polyester, a phosphorus compound as a coloring inhibitor, Inert particles other than the polymer particles may be included.

Examples of such inert particles include conventionally known inorganic particles such as silicon oxide, titanium oxide, aluminum oxide, and calcium carbonate, and a polyester polymerization reaction system in which an alkali metal or an alkaline earth metal and phosphorus are part of the components. The so-called internal particles that precipitate inside, or the particles other than the crosslinked polymer of the present invention include particles composed of a formaldehyde resin, a phenol resin, a silicone resin, and the like.

The polyester composition of the present invention can be applied to any of single-layer and multi-layer films.However, from the viewpoint of the smoothness of the film and the uniformity of the surface, a film composed of the polyester composition of the present invention is used. It can be a laminated film having at least one layer, particularly the outermost layer. Such a film can be manufactured by a conventionally known method.

[Example] Hereinafter, the present invention will be described in detail with reference to examples. In addition, each characteristic value measurement of the obtained polyester was performed according to the following method.

(A) Particle diameter and weight average diameter / number average diameter (D _W /
D _N ) ratio Average particle size was measured by electron micrograph of the particles
It was determined by the particle equivalent sphere diameter at the point of 50% by volume. The equivalent sphere diameter is the diameter of a sphere having the same volume as a particle.

The weight average diameter (D _W ) and number average diameter (D _N ) are individually obtained by numerical processing using an image analyzer (for example, QTM-900; manufactured by Cambridge Instrument).
The ratio was taken.

(B) Intrinsic viscosity of polymer Measured at 250 ° C. using o-chlorophenol as a solvent.

(C) Pyrolysis temperature of particles Temperature rise rate 20 ° C / m under nitrogen atmosphere with Rigaku Denki TAS-100
The thermobalance weight loss curve in was measured. The 10% weight loss temperature was taken as the pyrolysis temperature.

After the ultra-thin sections of the front and rear 0.3μ by ultrathin film producing apparatus particle dispersion state polymer in (D) a polymer, with a transmission electron microscope to observe the state of dispersion of the particles in the polymer, of 0.01 mm ² per field The number of secondary aggregated particles was counted.

(E) Film properties (1) Surface roughness Ra (μm) Measured using a stylus type surface roughness meter according to JIS-B-0601 (cutoff value 0.08 mm, measurement length 4 mm).

(2) Slipperiness (μk and μs, μd) (a) Slit μk film to 1/2 inch and use tape running tester TBT-300 type (Yokohama System Laboratory Co., Ltd.) to obtain 20 The vehicle was run in an atmosphere of 60 ° C. and 60% RH, and the initial μk was determined by the following equation.

μk = 0.733 log (T ₁ / T ₂ ) where T ₂ is the entrance tension and T ₁ is the exit tension. The guide diameter is 6mmφ, and the guide material is SUS27 (surface roughness 0.2
S), each winding is 180 ゜, running speed is 3.3cm / sec.

Those having the above μk of 0.35 or less have good slipperiness.
Here, μk is 0.35, which is a critical value as to whether or not the slipperiness when processing a film or as a product is extremely deteriorated.

(3) Abrasion resistance After using the tape running tester RBT-300 (manufactured by Yokohama System Research Institute Co., Ltd.) for 1,500 times in an atmosphere of 25 ° C. and 50 RH, the white color adhered to the guide part The shaved powder (white powder) is visually determined.

Here, the guide diameter is 8mmφ, and the guide material is SUS27
(Surface roughness 0.2S), winding angle 180 °, tape running speed 3.3cm / sec. The evaluation criteria are as follows.

A: The amount of white powder generated is very small, and the object is achieved.

；: The amount of white powder generated is small, and the object is achieved.

Δ: The amount of white powder generated was rather large, and the object was not achieved.

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

Example 1 An undried polyethylene terephthalate chip having an intrinsic viscosity of 0.650 containing 0.4% by weight of water was made into a molten state using a vent type twin screw extruder, and the content in the final polymer was changed to 2% by weight. %, A water slurry of two types of styrene-divinylbenzene copolymer particles having an average particle diameter of 0.3 μm and an average particle diameter of 0.05 μm (11.0% by weight based on polymer) was added. 10 Torr vent
The resin was melt-extruded at a resin temperature of 280 ° C. to obtain polyethylene terephthalate containing styrene-divinylbenzene copolymer particles. The intrinsic viscosity of the obtained polymer was 0.605, and a polymer with extremely small decrease in the intrinsic viscosity was obtained. As a result of observing the polymer with a transmission electron microscope, the number of secondary agglomerations per field of view of 0.01 mm ² was 12,
It was present in a nearly monodispersed state.

The obtained polymer was prepared using a polymer containing no styrene-divinylbenzene copolymer particles so as to contain 0.5% by weight of the styrene-divinylbenzene copolymer particles.
, And the mixture was wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method to be cooled and solidified to obtain an unstretched film having a thickness of about 150 μm. This unstretched film is 3.4 times longer at 90 ° C in the longitudinal direction and 3.times.
Stretched 6 times. Then, it heat-set at 210 degreeC, and obtained the biaxially stretched film of 15 micrometers in thickness. As a result of evaluating the film properties, the flatness, slipperiness, and abrasion resistance were all good (Table 1).

Examples 2 to 7, Comparative Examples 1 and 2 A vented extruder as in Example 1 except that the particle composition of the crosslinked polymer particles contained (including those having a functional group introduced into the particles) and the average particle diameter were changed. Was used to obtain polyethylene terephthalate. The particle dispersion state in the polymer was almost monodisperse with little secondary aggregation. The polymer was made into a biaxially oriented film in the same manner as in Example 1. When the film composition and average particle diameter of the crosslinked polymer contained were within the range of the present invention, when formed into a film, both flatness, slipperiness, and abrasion resistance were excellent (Examples 2 to 7).

However, when the average particle size of the crosslinked polymer particles is outside the scope of the present invention and when a single component crosslinked polymer is used, when formed into a film, both flatness, slipperiness, and abrasion resistance can be satisfied. No (Comparative Examples 1 and 2).

Comparative Examples 3 and 4 Polyethylene terephthalate having an intrinsic viscosity of 0.620 was dried at a concentration of 180 ° C. under reduced pressure. The chip and average particle size 0.3μm
And styrene-acrylonitrile-divinylbenzene copolymer powder / styrene-divinylbenzene copolymer powder of 0.05 μm and wet silica powder having an average particle diameter of 1.1 μm were compounded by 2% by weight using an extruder, and polyethylene terephthalate containing each particle was mixed. Obtained. The dispersion state in the polymer was very poor, and most of the particles were aggregated. The obtained polymer was made into a biaxially oriented film in the same manner as in Example 1. The surface of the obtained film had many coarse particles and could not satisfy both the slipperiness and the abrasion resistance.

[Effects of the Invention] The polyester composition of the present invention is monodispersed in a polymer and has a specific range of a ratio Dw / Dn. Excellent effect is exhibited.

In the present invention, since the crosslinked polymer particles are uniformly monodispersed in the polyester, for example, in the case of forming a film, there is no clogging of the filter in the melt molding process, and there is no breakage of the film due to the coarse particles.

In the present invention, since the crosslinked polymer particles are uniformly monodispersed in the polyester, a uniform uneven surface can be obtained when the stretched film is formed. Further, the crosslinked polymer particles have a good affinity for the polyester and are composed of two specific components, so that the slipperiness and abrasion resistance are further improved as compared with a single component. Such a film is suitable for magnetic tape applications, photography, plate making applications, condenser applications, and the like.

Claims (8)

(57) [Claims] 1. A polyester comprising a bifunctional acid component mainly composed of an aromatic dicarboxylic acid and at least one glycol component, a crosslinked polymer particle (a) having an average particle size of 0.01 μm or more and less than 0.1 μm and an average particle size. The crosslinked polymer particles (b) having a diameter of 0.1 to 5 μm are contained in a uniform monodispersed state, and the weight average diameter Dw in the particle size distribution of the crosslinked polymer particles (a) and the crosslinked polymer particles (b) as a whole is Ratio of number average diameter Dn
Dw / Dn is 1.3-10, The polyester composition characterized by the above-mentioned. 2. The polyester composition according to claim 1, wherein the thermal decomposition temperature of at least one of the crosslinked polymer particles is 380 ° C. or higher. 3. The polyester composition according to claim 1, wherein the content of the crosslinked polymer particles (a) relative to the crosslinked polymer particles (b) is 0.01 to 5% by weight. 4. The polyester composition according to claim 1, wherein at least one of the crosslinked polymer particles has a functional group. 5. The polyester composition according to claim 1, wherein the number of secondary aggregated particles is 30 or less per 0.01 mm ² . 6. The polyester composition according to claim 1, wherein the polyester is a polyester containing a 2,6-naphthalenedicarboxylic acid unit as a main acid component. 7. A film comprising the polyester composition according to claim 1. 8. When forming the polyester composition according to any one of claims 1 to 6, a crosslinked polymer particle having an average particle diameter of 0.01 μm or more and less than 0.1 μm is added to the polyester by a vent-type molding machine. A method for producing a polyester composition, comprising adding water of a crosslinked polymer particle having a particle size of 0.1 to 5 μm and / or a slurry of an organic compound having a boiling point of 200 ° C. or less, followed by molding.