JP3082239B2 - Polyester composition - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a polyester composition, and more particularly, to a polyester containing divinylbenzene / ethylvinylbenzene copolymer particles and branched / linear colloidal silica particles. Composition.

[Prior Art] Generally, thermoplastic polyesters, for example, polyethylene terephthalate, have excellent mechanical properties and chemical properties, and are widely used as molded products such as films and fibers.

However, when processing polyester into molded products,
There was a problem that productivity was reduced due to lack of slipperiness. As a method of solving such a problem, a method of dispersing inert particles in polyester to impart unevenness to the surface of a molded product has been conventionally performed (for example, Japanese Patent Application Laid-Open No.
-86471, JP-A-59-171623, etc.). These methods are effective for solving the problem of slipperiness, but when formed into a molded product, the abrasion resistance and scratch resistance cannot be brought to a satisfactory level.

If the abrasion resistance of a molded product, for example, a film for a magnetic tape, is low, abrasion powder of the film is likely to be generated during a manufacturing process of the magnetic tape, and a coating omission occurs in a process of applying a magnetic layer. It causes dropouts. In addition, when using a magnetic tape, in many cases, to run while contacting recording, playback equipment, etc.,
Abrasion powder generated at the time of contact adheres to the magnetic material, causing dropout of magnetic recording during recording and reproduction.

If the molded product, for example, a film for magnetic tape has low scratch resistance, or if foreign matter is generated during the manufacturing process of the magnetic tape, a scratch is easily formed on the film surface, and as a result, the magnetic recording is lost (drop-out). ), Etc., and easily scratches the film surface when using magnetic tape at high speeds.

That is, the film for a magnetic tape needs to have slipperiness, abrasion resistance, and scratch resistance both during the magnetic tape manufacturing process and when used as a magnetic tape. As a method for improving abrasion resistance, there is a method of containing fine particles. For example, one or more kinds of inert inorganic particles such as calcium carbonate, titanium oxide, and colloidal silica (large particles and small particles) are used. Conventionally, addition of organic particles such as crosslinked polymer particles has been conventionally performed. But,
In the current situation where the required level for the film performance is increasing, the performance required for the film surface is more advanced in order to simultaneously satisfy the above contradictory characteristics,
At present, satisfactory results have not yet been obtained.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and in particular, when formed into a film, a polyester composition excellent in all of slipperiness, abrasion resistance and scratch resistance. To get things.

Means for Solving the Problems An object of the present invention is to provide a polyester comprising a difunctional acid component mainly composed of an aromatic dicarboxylic acid and at least one glycol component, and a divinylbenzene having an average particle size of 0.01 to 5 μm.・ Ethylvinylbenzene copolymer particles, and the ratio D ₁ / D _{2 of the} particle diameter (D ₁ mμ) measured by the dynamic light scattering method to the particle diameter measured by the nitrogen gas adsorption method (D ₂ mμ) is 2 or more. Te, D ₁ is 60～600Emumyu, in electron microscopy
This is achieved by a polyester composition comprising branched and linear colloidal silica particles having a thickness in the range of 41 to 100 μm.

The bifunctional acid component of the polyester of the present invention is mainly composed of an aromatic dicarboxylic acid or an ester-forming derivative thereof.Specifically, terephthalic acid, 2,6-naphthalene dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4-4'-dicarboxylic acid, its ester-forming derivatives such as dimethyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, 1,2-bis (2-chlorophenoxy) ethane-4, Examples thereof include dimethyl 4-dicarboxylate, with terephthalic acid or dimethyl terephthalate being preferred. Examples of the glycol component include ethylene glycol, butylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, and 1,4-cyclohexanedimethanol. Of these, ethylene glycol is preferable. These dicarboxylic acids or their ester-forming derivatives and glycol components can be used alone or in combination of two or more. Further, other components may be used as copolymer components. Specific examples of the copolymer component when using terephthalic acid or an ester-forming derivative thereof as the difunctional acid component and ethylene glycol as the glycol component include diethylene glycol, propylene glycol, neopentyl glycol, polyalkylene glycol, and p Diol components such as -xylylene glycol, 1,4-cyclohexanedimethanol, 5-sodium sulforesorcin, adipic acid, sebacic acid, phthalic 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 oxydicarboxylic 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 performed at high temperature and reduced pressure to obtain a polyester.

It is also possible to carry out polycondensation using the prepolymer itself as a starting material.

One of the particles used in the present invention is a divinylbenzene / ethylvinylbenzene copolymer particle, and the composition ratio thereof is not particularly limited, but the amount of divinylbenzene units in the particle is 50% by weight in terms of monomer. Exceeded, especially 54% by weight
Those described above are preferred. Above all, 100% of commercially available divinylbenzene (containing ethylvinylbenzene and a small amount of diethylbenzene in addition to divinylbenzene) is polymerized,
Particles are preferred. In this case, divinylbenzene has a composition of 54% by weight or more as a pure component in the particles. If divinylbenzene is less than 50% by weight, particle aggregation may occur during polyester polymerization or melt molding,
In that case, the slipperiness and wear resistance tend to deteriorate.

Further, other components may be contained in the divinylbenzene / ethylvinylbenzene copolymer particles of the present invention, and examples thereof include styrene, polystyrene, and diethylbenzene which is an impurity of commercially available divinylbenzene. Can be

Further, the divinylbenzene / ethylvinylbenzene copolymer particles used in the present invention are preferably heat-resistant particles having a thermal decomposition temperature (a 10% weight loss temperature) of 390 ° C. or more measured by a thermobalance. Preferably, the thermal decomposition temperature is 400 ° C or higher, more preferably 410 ° C or higher. If the thermal decomposition temperature is lower than 390 ° C., particles may be aggregated during polyester polymerization or melt molding, in which case the slipperiness and abrasion resistance deteriorate.

The divinylbenzene / ethylvinylbenzene copolymer particles used in the present invention preferably have a spherical shape and a uniform particle size distribution from the viewpoint of lubricity and abrasion resistance.

That is, those having a volume shape factor of 0.35 to π / 6 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 is the particle volume (μm ³ ), and D is the maximum diameter (μm) of the particle on the projection surface. For example, in the method of pulverizing into fine particles disclosed in JP-A-55-158937, the particle shape is irregular. It is difficult to obtain a uniform particle size distribution, and coarse particles are present. Especially when the film is formed, the filter is clogged at the time of film formation, and the lubricity and abrasion resistance of the product are unfavorably deteriorated.

As the divinylbenzene / ethylvinylbenzene copolymer particles of the present invention, those obtained by a known production method can be used. As a known production method, for example, there is a method by emulsion polymerization as described below.

(1) 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.

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

(3) 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.

(4) JP-A-54-97582 and JP-A-54-12628
No. 8, a polymerization method using Eugelstatt or the like.

(5) A polymerization method using no swelling aid in the method of (4).

In the present invention, in order to improve the affinity between the divinylbenzene / ethylvinylbenzene copolymer particles and the polyester, it is particularly preferable to use divinylbenzene / ethylvinylbenzene copolymer particles having an alkali metal salt of a carboxyl group as a functional group. preferable. Examples of the alkali metal salt of a carboxyl group include a Na salt, a K salt, and a Li salt. Among them, a Na salt of a carboxyl group is preferable because the affinity is further improved. The chemical species having a functional group for introducing an alkali metal salt of a carboxyl group may be a monomer or a polymer, and is not particularly limited.
Of these, methacrylic acid, acrylic acid, and polymers thereof are preferred. Further, the chemical species having a carboxyl group may be a chemical species having no functional group or a chemical species having a functional group other than the carboxyl group may be copolymerized. preferable. The method for introducing the alkali metal salt of a carboxyl group is not particularly limited, but once a highly crosslinked parent particle is produced from the viewpoint of heat resistance of the particle, the alkali metal salt of the carboxyl group is formed on the surface of the parent particle. Preferably, it is introduced. For example, in a divinylbenzene / ethylvinylbenzene copolymer as a base particle, a particle highly crosslinked with divinylbenzene is produced, and then a carboxyl group is introduced into the particle surface with methacrylic acid. By setting the inside of the particle production system to the alkali side, -CO
A functional group of ONa is introduced. The amount of the monomer or polymer for introducing the alkali metal salt of the carboxyl group is preferably 0.01 to 20% by weight based on the base particles, and 0.1 to 20% by weight.
1-10% by weight is more preferred.

The average particle size of the divinylbenzene / ethylvinylbenzene copolymer particles used in the present invention must be 0.01 to 5 μm, and more preferably 0.05 to 2 μm. If the average particle size is less than 0.01 μm, when the film is formed, the slipperiness decreases. On the other hand, if the average particle size exceeds 5 μm, abrasion resistance and scratch resistance deteriorate due to generation of voids and coarse projections.

When divinylbenzene / ethylvinylbenzene copolymer particles having an average particle size of 0.01 to 5 μm are used, the average particle size as the first component is 0.01 μm or more and less than 0.1 μm, preferably 0.01 μm or more and less than 0.08 μm, and more preferably. Is 0.02
It is easy to use divinylbenzene / ethylvinylbenzene copolymer particles composed of a two-component system having an average particle diameter of 0.1 to 5 μm, preferably 0.1 to 2 μm as a second component, which is not less than μm and less than 0.06 μm. It is preferable because lubricity is improved. Further, when divinylbenzene / ethylvinylbenzene copolymer particles composed of two components are dispersed and contained in polyester, the weight average diameter D _W and the number average diameter of the entire two components are obtained.
The value of the ratio D _W / D _N and D _N is preferably 1.2 to 10, still more preferably 1.2 to 5.

When divinylbenzene / ethylvinylbenzene copolymer particles composed of two components are dispersed and contained in polyester, two types of divinylbenzene / ethylvinylbenzene copolymer particles are separately produced, and the particles obtained are mixed. Although it may be dispersed and contained in the polyester, from the viewpoint of workability, cost and surface flatness, two kinds of particles are simultaneously produced in the production stage of the divinylbenzene / ethylvinylbenzene copolymer particles and dispersed in the polyester. It is preferable to make it contained.

When the two-component divinylbenzene / ethylvinylbenzene copolymer particles are used as described above, the amount of the divinylbenzene / ethylvinylbenzene copolymer particles added as the second component is usually 0.0001 to 10 wt. %, More preferably 0.001 to 15% by weight, even more preferably 0.01 to 5% by weight. The amount of the divinylbenzene / ethylvinylbenzene copolymer particles as the first component is usually 0.01 to 5% by weight, more preferably 0.01 to 5% by weight, based on the divinylbenzene / ethylvinylbenzene copolymer particles of the second component. ~ 3% by weight, more preferably 0.05 ~
2% by weight.

Further, the divinylbenzene / ethylvinylbenzene copolymer particles of the first component and the second component may both have an alkali metal salt of a carboxyl group as a functional group. It is preferable that the benzene copolymer particles have an alkali metal salt of a carboxyl group as a functional group.

In order to improve the heat resistance or control the refractive index of the divinylbenzene / ethylvinylbenzene copolymer particles, the divinylbenzene / ethylvinylbenzene copolymer particles are coated with an inorganic substance such as SiO ₂ or TiO ₂ around the particles. Is also good.

The branched / linear colloidal silica particles of the present invention have a particle diameter D ₁ measured by a dynamic light scattering method in a slurry state.
Has a size of 60 to 600 mμ, and has a shape extending in a uniform thickness in the range of 41 to 100 mμ when observed with an electron microscope. Measurement of particle diameter by the dynamic light scattering method, Journa 1 of Chemical Physics are described in Vol. 57, No. 11 (December 1972) pp. 4814, for example, a commercially available US Coulter, Inc. N ₄ The particle size can be easily measured by a measuring device called "A". D ₁ is undesirable poor dispersibility in the polyester is less than 60Emumyu.
Further, when D ₁ exceeds 600Emumyu, for example, since worsens the flatness of the film is not preferred. Then, a nitrogen gas adsorption method (hereinafter, referred to as a BET method) is used as an approximate degree of elongation of the particles.
From the value of the specific surface area Sm ² / g of this particle measured by D
The ratio D ₁ / D ₂ between the converted particle diameter D ₂ mμ and the above-mentioned D ₁ mμ given by the equation ₂ = 2720 / S is 2 or more.
Here, the value of D ₁ / D ₂ is 2 or more and less than 10, more preferably 2 or more and less than 7, and particularly preferably 2 or more and less than 5, the dispersibility of particles in polyester, the slipperiness of polyester,
Good abrasion resistance and scratch resistance.

The shape of the branched / straight colloidal silica particles in the present invention may be linear or may be bent, and may have a branch point and elongation. It is difficult to distinguish the shape from the secondary aggregates and the overlap of particles,
In the case of a stable sol, it is fixed to a collodion film by appropriate dispersion treatment, and when observed by dispersing with a transmission electron microscope, it has a linear or branched shape with almost uniform thickness and the same brightness Particles can be observed. The determination that this is not a secondary aggregate is because the secondary aggregate is not observed as having a substantially uniform thickness. The judgment that the particles do not overlap is because there is basically no portion having different intensities.

The colloidal silica having a linear or branched shape in the present invention may be either crystalline or amorphous, but amorphous is preferred. The particles are usually stored in a stable slurry.

The branched / straight colloidal silica of the present invention is produced, for example, as follows. First, an appropriate amount of an aqueous solution containing a water-soluble calcium salt or magnesium salt is added to a colloidal aqueous solution of active silicic acid having a pH of 6 or less and mixed. Next, an appropriate amount of an alkali metal hydroxide, a water-soluble organic base or a water-soluble silicate thereof is added and mixed, and the mixture is heated at 60 ° C. or higher for an appropriate time. At this time, a water slurry of activated silicic acid
It is preferable to add a trivalent metal salt. The colloidal silica produced in this manner has a linear or branched shape, and contains an initial amount of an aqueous solution containing a PH, calcium salt or magnesium salt, an alkali metal hydroxide, a water-soluble organic base or a mixture thereof. The shape can be controlled by the amount of water-soluble silicate added, the manner of mixing, the heating temperature and the time. The added calcium salt or magnesium salt is preferably in a weight ratio of 300 ppm to 1500 ppm with respect to SiO ₂ in the aqueous colloid solution, and is preferably 500 ppm to 1200 p.
pm is more preferred.

The method for adding the fine branched / linear colloidal silica particles in the present invention is not particularly limited, but it is generally preferable to add a slurry in a stable sol state.

Weight ratio 50p converted to SO ₃ with respect to SiO ₂ which sulfur atom compound in the slurry constituting the colloidal silica particles in order to improve the dispersibility of the particles in the polyester in the present invention
It is preferably present in the range from pm to 3000 ppm. Another 100
The content is preferably not less than ppm and not more than 2500 ppm. If the content exceeds 3000 ppm, secondary aggregation of particles in the polyester occurs,
It is not preferable because foreign substances are generated due to the sulfur atom-containing compound. If the content is less than 50 ppm, secondary aggregation of particles in the polyester occurs, which is not preferable. S atoms are added at the time of particle production, for example, as sulfates.

In order to obtain the stability of the slurry, it is preferable that the amount of Na in the slurry is not less than 1000 ppm and not more than 20,000 ppm by weight in terms of Na ₂ O with respect to SiO ₂ constituting the colloidal silica particles. Preferably, the concentration is 2000 ppm or more and 7000 ppm or less. If the content exceeds 20,000 ppm, particles tend to agglomerate during storage of the slurry, which is not preferable. Further, it is not preferable in terms of the production method to make the content less than 1000 ppm. Na is added at the time of particle production, for example, as an alkali metal hydroxide.

Further, the particle slurry used in the present invention may contain other components, and may contain trace amounts of cations and anions.

Further, when the film is formed, the average particle size of the divinylbenzene / ethylvinylbenzene copolymer particles (A) and the dynamics of the branched / linear colloidal silica (B) are considered from the viewpoints of lubricity, abrasion resistance and scratch resistance. Particle size measured by dynamic light scattering method
D ₁ is more preferably a condition satisfying the following expression.

0.3 .mu.m.ltoreq. (A) .ltoreq.2.0 .mu.m 60 .mu.m.ltoreq. (B) .ltoreq.200 m. Further, the addition amount of divinylbenzene / ethylvinylbenzene copolymer particles and branched / linear colloidal silica particles to the polyester is preferably 0.001 to 10 respectively.
% By weight, more preferably 0.005 to 5% by weight, and still more preferably 0.01 to 2% by weight, respectively.

The divinylbenzene / ethylvinylbenzene copolymer particles and the branched / linear colloidal silica particles of the present invention can be added to and mixed with polyester by various known methods. May be added to the polyester production stage,
It may be added to and mixed with the polymer in a molten state by using a single-screw or twin-screw extruder or an extruder having a vent mechanism. When it is added during the polyester production stage, it is particularly preferred from the viewpoint of particle dispersibility that it is added before the start of polyester polymerization and during the polymerization reaction. The addition of the particles in the precursor stage or the polycondensation stage before the production of the polyester composition is preferably performed as a slurry of ethylene glycol. An appropriate slurry concentration is about 0.5 to 20% by weight.

As a method of dispersing in a dispersion medium such as ethylene glycol, for example, a high-speed disperser, a sand mill, a roll mill, or the like may be used.

When the divinylbenzene / ethylvinylbenzene copolymer particles and the branched / linear colloidal silica particles of the present invention are used, the divinylbenzene / ethylvinylbenzene copolymer particles have good affinity, and the branched / linear colloidal silica particles have good affinity. Since the particles have a special shape, they do not easily fall off the polyester. As a result, when the film is formed, the film can have both slipperiness, abrasion resistance, and scratch resistance.

Incidentally, the composition of the present invention further includes lithium, sodium, calcium, which are generally used in the production of polyester.
Inorganic substances other than metal chemical catalysts of compounds such as magnesium, manganese, zinc, antimony, germanium, and titanium, phosphorus compounds as coloring inhibitors, divinylbenzene / ethylvinylbenzene copolymer particles, and branched / linear colloidal silica particles Particles, organic polymer fine particles, and the like can be appropriately added as necessary.

[Examples] Hereinafter, the present invention will be described in detail with reference to examples. In addition, each characteristic value measurement of the obtained polyester composition was performed according to the following method. The colloidal silica particles and divinylbenzene / ethylvinylbenzene copolymer particles used were produced according to the method described in the detailed description of the invention.

(A) Particle characteristics a. Divinylbenzene / ethylvinylbenzene copolymer particles (1) Particle size The average particle size was measured by an electron micrograph of the particles.
It was determined by the particle equivalent sphere diameter corresponding to the volume% point. The equivalent sphere diameter is the diameter of a sphere having the same volume as a particle.

The weight average diameter (D _W ) and the number average diameter (D _N ) were individually obtained by numerical processing using an image analyzer (for example, QTM-900: manufactured by Cambridge Instrument), and ratios were obtained.

(2) Thermal decomposition temperature of particles Temperature rise rate 20 ° C / m in a 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.

b. was measured using a particle diameter measured (D ₁ m.mu.) commercial US Coulter, Inc. N ₄ by the branch-linear colloidal silica particles (1) a dynamic light scattering method.

(2) Particle size measured by nitrogen gas adsorption method (D ₂ mμ) The converted particle size given by the formula of D ₂ = 2720 / S was measured from the value of specific surface area Sm ² / g measured by a normal BET method. .

(3) Thickness of particles (D ₃ mμ) to be observed by electron microscope Observation of primary particles using a transmission electron microscope after the particle-containing polyester composition is cut into an ultrathin section of about 0.3 μm using an ultrathin film forming apparatus. Then, the thickness of the particles was measured.
Here, the primary particles in the polyester, the slurry is diluted with a mixed solvent of methanol and water, the particles are dispersed, the primary particles are observed using a transmission electron microscope, and the particles in the polyester similar to the particles are observed. Say that.

(4) Sulfur atom-containing compound content The slurry was measured by an ion chromatography method.

(5) Na Content The slurry was measured by an ion chromatography method.

(B) Polymer properties (1) Fixed viscosity This is a value measured at a concentration of 0.1 g / cc in orthochlorophenol at 25 ° C.

(C) Film characteristics (1) Surface roughness Ra (μm) Using a surfcom surface roughness meter according to JIS-B-0601
Needle diameter 2μm, load 70mg, measurement standard length 0.25mm, cut off
The center line average roughness measured under the condition of 0.08 mm was employed.

(2) a slipping property (mu _K) film was slit to 1/2 inch, using a tape running tester TBT-300 type (KK Yokohama System Laboratory), 20 ° C., in 60% RH atmosphere It is run, and the initial of μ _K obtained from the following formula. The guide diameter is 6mmφ, the guide material is SUS27 (surface roughness 0.2S), the winding angle is 180 °,
The running speed is 3.3 cm / sec.

_{μ K = 0.733log (T 1 /} T 2) T 1: exit side tension T _2: the inlet side as tension the mu _K is 0.35 or less is a sliding property good.
Here, when the mu _K becomes larger than 0.35, the slipping property becomes extremely poor when formed into a film during processing or product.

(3) Wear resistance Using a tape running tester TBT-300 (manufactured by Yokohama System Laboratory Co., Ltd.), after running 100 times repeatedly in an atmosphere of 35 ° C and 60RH, white shavings adhered to the guide part. The 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 ゜, running speed 3.3cm
Per second. The evaluation criteria are as follows.

Grade 1: No adhesion Grade 2: Slightly adhered Grade 3: A large amount of adhesion Grade 4: Adhered to the entire surface (4) Scratch resistance The tape was run by slitting the film into a 1/2 inch wide tape. Run on a guide pin (surface roughness: 0.1 μm in Ra) using a tester. (Running speed 1,000m
/ Min, 200 passes, winding angle 60 °, running tension 65
g) At this time, observe the scratches in the film with a microscope,
Less than 2 scratches of 2.5μm or more per tape width are first class, 2
Two or more and less than three were classified as second grade, three or more and less than ten were classified as third grade, and ten or more were classified as fourth grade.

Example 1 First, measure the particle diameter D ₁ is 165mμ by a dynamic light scattering method, BE
T method by measuring the particle diameter D ₂ is 45Emumyu, transmissive-type amorphous colloidal silica particles 5 parts by weight thickness of 45μm of electron microscopy by the particles, 95 parts by weight of ethylene glycol, converted to SO ₃ with respect to SiO ₂ 1700 ppm For sulfur atom compounds, SiO ₂
930 ppm in terms of CaO with respect to 6500 ppm of Na and SiO _{2 in} terms of Na ₂ O
A slurry of 100 parts by weight of Ca was prepared.

Next, 100 parts by weight of dimethyl terephthalate, 62 parts by weight of ethylene glycol, and 0.06 parts by weight of magnesium acetate were added to carry out a transesterification reaction, and a thermal decomposition temperature of 405 was obtained by dispersing 6 parts by weight of the previously prepared slurry as an ethylene glycol slurry. Divinylbenzene / ethylvinylbenzene copolymer particles having an average particle size of 0.6 μm at 100 ° C. [commercially available divinylbenzene 100% (divinylbenzene 55%, ethylvinylbenzene 40%, diethylvinylbenzene 5%)
Polymerized. [Volume shape coefficient 0.51] 0.05 parts by weight and 0.03 parts by weight of antimony oxide are added to carry out a polycondensation reaction, and [η] 0.60
Thus, a polyethylene terephthalate composition of No. 0 was obtained. The polyethylene terephthalate composition obtained here was melt-extruded at 290 ° C. to obtain an unextended film. And this
Stretch 3 times in each of longitudinal and transverse directions at 90 ° C and 10 at 220 ° C
Heat treatment was performed for a second to obtain a film having a thickness of 15 μm. As a result of evaluating the film characteristics, it was found that all of the sliding properties, abrasion resistance and scratch resistance were good. (Table 1) Examples 2 to 8 and Comparative Examples 1 to 4 Colloidal silica particles have a particle diameter D ₁ measured by a dynamic light scattering method, a particle diameter D ₂ measured by a BET method, thickness, and divinylbenzene / ethylvinyl. A polyester composition and a biaxially stretched film were obtained in the same manner as in Example 1 except that the average particle size of the benzene copolymer particles was changed.

The colloidal silica particles containing D ₁ · D ₁ / D ₂ , the thickness and the average particle size of the divinylbenzene-ethylvinylbenzene copolymer particles are within the range of the present invention, when formed into a film, slippery , Abrasion resistance and scratch resistance were both excellent (Examples 2 to 8).

However, when the average particle diameter of _{D 1, D 1 / D 2} , the thickness and divinylbenzene ethylvinylbenzene copolymers of the colloidal silica particles is outside the present invention, sliding property, wear resistance,
Both of the scratch resistances could not be satisfied (Comparative Examples 1 to 4).

Comparative Examples 5 to 8 When colloidal silica particles and divinylbenzene / ethylvinylbenzene copolymer particles are used alone as particles to be contained, spherical colloidal silica particles and styrene-acryl copolymer particles are used in combination. ,
In the same manner as in Example 1, a biaxially oriented film of polyethylene terephthalate was obtained. None of them could satisfy both the slip property, abrasion resistance and scratch resistance.

[Effects of the Invention] The polyester of the present invention contains divinylbenzene / ethylvinylbenzene copolymer particles and branched / linear colloidal silica particles. The branched and linear colloidal silica particles have a special shape, so they do not easily fall off the polyester and have good affinity. , The scratch resistance can be more highly satisfied. Such a film is suitable for magnetic tape applications.

Further, the two particles of the present invention are excellent in affinity and excellent in transparency and electrical properties. Such a film is suitable for use in photography, plate making, condenser use and the like.

────────────────────────────────────────────────── (5) References JP-A-2-245056 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 67/00-67/02

Claims (1)

(57) [Claims] 1. A polyester comprising a difunctional acid component mainly composed of an aromatic dicarboxylic acid and a glycol component, divinylbenzene / ethylvinylbenzene copolymer particles having an average particle size of 0.01 to 5 μm, and a dynamic light scattering method. a is granulometry (D ₁ mμ) and measured particle size by nitrogen gas adsorption method (D ₂ m.mu.) the ratio D ₁ / D ₂ is 2 or more by, D ₁ is 60～600Emumyu, in electron microscopy A polyester composition comprising branched and linear colloidal silica particles having a thickness in the range of 41 to 100 mμ.