JPH08302171A - Polyester composition and polyester film - Google Patents

Abstract

PURPOSE: To improve the formability into films, slipperiness, and scraping resistance by kneading a polyester and specified fine silicon resin particles in a vented double-screw kneading extruder. CONSTITUTION: Polyester pellets and 0.005 to 10wt.% fine silicone resin particles having an average particle diameter of 0.05 to 3μm wherein 80wt.% or more of the particles are made up of bonding units represented by the formula, RSiO3/2 (wherein R stands for at least one member selected from among C1-6 alkyl and phenyl groups) are fed to supply ports 2 and 5 of a vented double- screw kneading extruder and melt kneaded with the degree of vacuum at vents 4 and 6 being set at 10mmHg or less to obtain a polyester composition. After the composition is melted at 280 to 300 deg.C, it is extruded through a slit die and is quenched to obtain an unstretched film. The film is stretched in one direction 2.5-fold or more, then is stretched in the direction normal to the first direction 2.5-fold or more, and is thermoset to obtain the intended polyester film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester composition and a polyester film, and more particularly, a polyester composition in which silicone resin fine particles are well dispersed in polyester and which is excellent in film-forming property, and a flat surface using the composition. The present invention relates to a biaxially oriented polyester film excellent in slipperiness and abrasion resistance.

[0002]

2. Description of the Related Art Biaxially oriented polyester films represented by polyethylene terephthalate films are used for various purposes, especially for magnetic recording media because of their excellent physical and chemical properties.

In the biaxially oriented polyester film, its slipperiness and abrasion resistance are major factors that affect the workability of the film manufacturing process and processing process and the product quality. If these are insufficient, for example, when a magnetic layer is applied to the surface of a biaxially oriented polyester film and used as a magnetic tape, friction and abrasion between the coating roll and the film surface are severe, and wrinkles and scratches on the film surface are likely to occur. Even when it is used for a VTR or a data cartridge, friction is generated between many guide parts, a reproducing head, etc. during pulling out from a cassette, winding, and other operations, causing scratches, distortion, and even a base film. The generation of white powder due to scraping of the surface often causes dropout.

Many investigations have been made to solve these problems. Among them, the method of adding fine silicone resin particles (for example, JP-A-62-172031) has a great improvement effect and is expected to develop as a technology in the future. It

However, in addition to the physical properties of the film, the following phenomenon has been newly pointed out as a problem in the film containing the silicone resin particles.

That is, when a film containing the silicone resin fine particles is formed into a film, when a molten polymer is extruded from a slit die onto a rotary cooling drum, an electrostatic application method is usually used to improve sticking to the drum. The film-forming method used is adopted, but at this time the electrostatic wire easily gets dirty,
As a result, a current drop or discharge spark occurs, and the sticking effect decreases, so that the electrostatic wire must be replaced in a short period of time.

Since such a phenomenon becomes remarkable with an increase in the addition amount of the silicone resin fine particles, the problem is small in a high-grade application such as a film for a metal video tape in which the addition amount is relatively small, but the film is relatively harsh. It is necessary to increase the addition amount in order to run the film, and it becomes a problem in a film for a regular video tape which is required to have higher productivity, and this problem is awaited to be solved.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a silicone resin capable of stably satisfying both slipperiness and abrasion resistance of such a film, and capable of significantly reducing electrostatic wire contamination. It is intended to provide a polyester composition containing fine particles and a biaxially oriented polyester film using the composition.

[0009]

According to the present invention, a polyester having an average particle diameter of 0.05 to 3 μm and 80% by weight or more of the particles is a fine powder of silicone resin comprising a bonding unit represented by the following formula. It is a polyester composition blended in the state and kneaded with a vent type twin-screw kneading extruder.

[0010]

Embedded image RSiO _3/2 (wherein R is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group.)

The polyester in the present invention is a polyester having an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyesters are substantially linear and have film-forming properties, especially melt-forming film-forming properties.
As the aromatic dicarboxylic acid, for example, terephthalic acid,
2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid, biphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, anthracene dicarboxylic acid and the like can be mentioned. Examples of the aliphatic glycol include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol,
Examples thereof include polymethylene glycol having 2 to 10 carbon atoms such as decamethylene glycol and the like, and alicyclic diols such as cyclohexanedimethanol and the like.

In the present invention, a polyester containing alkylene terephthalate and / or alkylene naphthalate as a main constituent is preferably used as the polyester.

Among such polyesters, especially polyethylene terephthalate and polyethylene-2,6-naphthalate, for example, 80 mol% or more of the total dicarboxylic acid component is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, A copolymer in which 80 mol% or more of all glycol components is ethylene glycol is preferable. 20 mol% or less of the total acid component can be the above aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid. A cycloaliphatic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid. Further, 20 mol% or less of the total glycol component may be the above-mentioned glycol other than ethylene glycol, and aromatic diols such as hydroquinone, resorcin, and 2,2-bis (4-hydroxyphenyl) propane, 1, An aliphatic diol having an aromatic ring such as 4-dihydroxydimethylbenzene, polyalkylene glycol (polyoxyalkylene glycol) such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like can also be used.

The polyester of the present invention includes
Aromatic oxyacids such as hydroxybenzoic acid, ω-
Those in which a component derived from an oxycarboxylic acid such as an aliphatic oxyacid such as hydroxycaproic acid is copolymerized or bonded in an amount of 20 mol% or less based on the total amount of the dicarboxylic acid component and the oxycarboxylic acid component are also included.

The silicone resin fine particles contained in the polyester in the present invention have the following formula:

[0016]

Embedded image A crosslinked silicone resin having 80% by weight or more of a bonding unit represented by RSiO _3/2 (wherein R is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group). Particles.

The above-mentioned bonding unit means the following structural formula.

[0018]

[Chemical 4]

Here, R is the same as above.

Methods for producing the silicone resin fine particles are known, and for example, a method of hydrolyzing and condensing organotrialkoxysilane (for example, Japanese Examined Patent Publication No. 40-14917 or Japanese Examined Patent Publication No. 2-22767) or methyltrichlorosilane is used. Method for producing polymethylsilsesquioxane fine particles as a raw material (for example, Belgian Patent 57241)
No. 2) and the like. However, in the present invention, the production method is not limited as long as the particles have the characteristics described below, and silicone resin fine particles produced by any method may be used.

R in the above formulas [Chemical Formulas 1 to 3] and structural formula [Chemical Formula 4] is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group, and the alkyl group is, for example, a methyl group, Examples thereof include ethyl group, propyl group, butyl group, pentyl group and hexyl group. These can be one or more. When R is a plurality of groups, for example, when it is a methyl group and an ethyl group, it can be obtained by producing a mixture of methyltrimethoxysilane and ethyltrimethoxysilane as a starting material. However, considering the manufacturing cost and the ease of the synthesis method, the silicone resin (polymethylsilsesquioxane) fine particles in which R is a methyl group are preferable.

The silicone resin fine particles preferably have a substantially spherical shape, and in this case, they are particularly effective in imparting slipperiness.

The average particle diameter of the silicone resin fine particles in the present invention is 0.05 to 3 μm, preferably 0.3 to
It is 2.0 μm. If the average particle size is less than 0.05 μm, it is difficult to obtain the effect of improving the sliding property and the abrasion resistance, while the average particle size of 3 μ
If it exceeds m, it is difficult to obtain the surface flatness of the film, which is not preferable. Further, it is particularly effective that the silicone resin fine particles have a spherical particle shape because they are effective in imparting slipperiness.

The addition amount of the silicone resin fine particles in the present invention is 0.005-1 based on the weight of the polyester.
It is 0% by weight, preferably 0.005 to 5% by weight. If this addition amount is too small, the slipperiness of the film deteriorates,
On the other hand, if the amount added is too large, problems such as insufficient dispersibility in the polymer occur.

In the present invention, the polyester composition may contain fine particles of silicone resin alone, but may be combined with other fine particles, that is, other organic fine particles and / or inert inorganic particles depending on the use and physical properties of the film. May be included in. Other organic fine particles include crosslinked polystyrene fine particles, crosslinked acrylic resin fine particles, melamine resin fine particles and the like, and the inert inorganic fine particles include aluminum oxide, titanium oxide, silicon oxide, zirconium oxide,
Examples thereof include calcium carbonate, kaolin, clay and carbon black. The aluminum oxide may have various crystal forms,
α-type, γ-type, δ-type, θ-type, and κ-type aluminum oxide are preferable, and γ-type, δ-type, and θ-type aluminum oxide are particularly preferable.

The other fine particles used in combination with the silicone resin fine particles preferably have an average particle diameter of 0.05 to 2 μm. Also, the combined amount is based on the weight of polyester.
It is preferably 0.01 to 2% by weight.

In the present invention, the silicone resin fine particles are
It is necessary to directly mix the fine particles-free polyester (composition) in a vent type twin-screw kneading extruder and perform melt kneading while keeping the vent hole in vacuum.

At that time, it is necessary to mix the silicone resin fine particles in a powder state. When the fine particles are added as a slurry using water or an organic compound as a medium, removal of the medium supplied to the vent type twin-screw kneading extruder becomes insufficient, resulting in a significant decrease in the intrinsic viscosity of the polyester. Cheap.

The vented twin-screw kneading extruder used in the present invention preferably has a screw structure in which a kneading disk or a rotor type kneading element is arranged as shown in FIG. It is preferable to dispose reverse-threaded elements within a range that does not significantly lengthen, which is effective for ensuring the dispersibility of particles. The kneading conditions such as the cylinder temperature and the shaft rotation speed may be selected according to the dispersion state of the fine particles after the polyester type and the discharge amount are determined.

In the present invention, the silicone resin fine particle powder may be added to the bent type twin-screw kneading extruder at the same time as the pelletized polyester through the same supply port, or may be added to the molten polyester through another supply port. However, the former is preferable because the higher shear stress acts when the polyester melts and the dispersibility of the fine particles becomes higher. Further, after the fine particles are blended and kneaded by these methods, the dispersibility of the fine particles is further improved by additionally feeding and kneading pelletized polyester from a supply port provided at the downstream portion of the kneading extruder. It is also possible.

In the present invention, it is preferable that the degree of vacuum of the vent hole during kneading with the vent type twin-screw kneading extruder is kept sufficiently high. It is preferably 10 mmHg or less, more preferably 1 mmHg or less.

When producing a film using the polyester composition of the present invention, conventionally known methods can be applied. For example, a polyester composition or a mixture obtained by diluting the polyester composition with another polyester is melt-extruded and rapidly cooled to obtain an unstretched film, and then the unstretched film is stretched biaxially and heat-fixed, If necessary, it can be produced by relaxation heat treatment. At this time, the surface characteristics, density, heat shrinkage rate, and other properties of the film change depending on the stretching conditions and other manufacturing conditions, and are appropriately selected as necessary.

For example, the unstretched film is uniaxially (longitudinal or transverse) in the range of [Tg-10] to [Tg + 6].
At a temperature of 0] ° C. (however, Tg: glass transition temperature of polyester), the film is stretched at a draw ratio of 2.5 times or more, preferably 3 times or more, and then Tg to [Tg] in a direction perpendicular to the drawing direction.
It is preferable to stretch at a temperature of +70] ° C. at a draw ratio of 2.5 times or more, preferably 3 times or more. Further, if necessary, it may be re-stretched in the machine direction and / or the transverse direction. In this way, the total draw ratio is preferably 9 times or more, more preferably 12 to 35 times, and more preferably 15 to 15 times as the area draw ratio.
25 times is particularly preferable. Furthermore, the biaxially stretched film can be heat-set at a temperature of [Tg + 70] ° C. to [Tm-10] ° C. (however, Tm: melting point of polyester), for example, at 180-250 ° C. Preferably. The heat setting time is preferably 1 to 60 seconds.

In the present invention, the polyester film may be a single layer film, but may be a laminated film having two or more layers in some cases. In this case, the film layer using the polyester composition constitutes at least one of the outermost layers. The thickness of this film layer is preferably 0.3 μm or more.

The (total) thickness of the polyester film is preferably 4 to 25 μm, more preferably 5 to 20 μm for both the single layer film and the laminated film.

When the film containing the silicone resin fine particles using the polyester composition of the present invention is formed into a film, the electrostatic wire is less contaminated, and as a result, the ratio of troubles due to the decrease in current is significantly reduced. This is because the sublimable substance in the silicone resin, which causes electrostatic wire contamination, sublimes when the polyester composition is melt-kneaded by a vent-type twin-screw kneading extruder during the production of the polyester composition, It is thought that it is because it is removed through the vent hole of.

The polyester film of the present invention is excellent in stable slipperiness and abrasion resistance, and effective in stable productivity during film formation, and is particularly useful as a base film for magnetic recording media.

[0038]

EXAMPLES The present invention will be described in detail below with reference to examples. Also,
Various physical properties and characteristics in the present invention are measured and defined as follows.

(1) Average Particle Size of Fine Particles (d) (i) When Obtaining Average Particle Size from Granules Shimadzu SA-CP4L Centrifugal Particle Size Analyzer (Centrifugal Partic)
The particle size corresponding to 50 mass% is read from the integrated curve of the particle size calculated based on the centrifugal sedimentation curve obtained using the le Size Analyzer) and the abundance of particles having that particle size. The average particle size is used.

(Ii) In the case of fine particles in film The sample film is fixed on a sample stage for a scanning electron microscope, and a sputtering device (JFC-made by JEOL Ltd.) is used.
1100 type ion etching apparatus) is used to perform ion etching treatment on the film surface under the following conditions. The conditions were as follows: the sample was placed in a bell jar, the degree of vacuum was raised to a vacuum state of about 10 ⁻³ Torr, the voltage was 0.25 kV, and the current was 1
Perform ion etching at 2.5 mA for about 10 minutes. Further, gold sputtering is applied to the film surface with the same apparatus, and it is observed with a scanning electron microscope from 50,000 to 10,000.
Observed at double magnification, the equivalent spherical diameter distribution of at least 100 particles is obtained by Luzex 500 manufactured by Nippon Regulator Co., Ltd., and calculated from the point of 50% in weight accumulation.

(2) Running friction coefficient (μk) of film The measurement is carried out as follows using the apparatus shown in FIG.
In FIG. 2, 11 is an unwind reel, 12 is a tension controller, 13, 15, 16, 18, 18, and 19 are free rollers, 14 is a tension detector (entrance), 1
7 is a fixed rod made of stainless steel SUS304 (outer diameter 5 mm
φ, surface roughness Ra = 0.02 μm), 20 is a tension detector (outlet), 22 is a guide roller, and 23 is a take-up reel.

In an environment of temperature 20 ° C. and humidity 60%, width 1 /
The film cut into 2 inches is attached to the fixed rod 7 at an angle θ = (1
52/180) π radians (152 °) and moved (rubbed) at a speed of 200 cm per minute. The exit tension (T ₂ : g) when the tension controller 2 is adjusted so that the entrance tension T ₁ is 35 g is detected by the exit tension detector after the film has run 90 m, and the running friction coefficient μk is calculated by the following formula. calculate.

[0043]

[Number 1] μk = (2.303 / θ) log (T 2 / T 1) = 0.868log (T 2/35)

(3) Flatness of film surface Ra (center line average roughness) is measured according to JIS B 0601. Using a stylus type surface roughness meter (SURFCOM3B) manufactured by Tokyo Seimitsu Co., Ltd., a chart (film surface roughness curve) is drawn under the conditions of a needle radius of 2 μm and a load of 0.07 g to obtain a film. A portion of the measurement length L is extracted from the surface roughness curve in the direction of the center line, the center line of the extracted portion is taken as the X axis, the longitudinal magnification direction is taken as the Y axis, and the roughness curve Y = f (x) When expressed, the value (Ra: μm) given by the following equation is defined as the flatness of the film surface.

[0045]

[Equation 2]

In the present invention, 8 pieces are measured with a reference length of 0.25 mm, and Ra (μm) is expressed as an average value of 5 pieces excluding 3 pieces having a larger value.

(4) Scraping resistance In the same device as that used in FIG. 2 used for measuring the running friction coefficient μk, the winding angle was 30 degrees, and the running tension was 600 m at a speed of 300 m / min and an inlet tension of 50 g. Let The shavings adhering to the fixed rod 17 after running and the scratches of the tape after running are evaluated. Fixed rod 1 at this time
7, a 6 mm tape guide with an inadequate surface finish obtained by bending a SUS sintered plate into a cylindrical shape (surface roughness Ra = 0.1
5 μm) is used. <Judging powder judgment> ⊚: No shavings are observed. ○: A slight amount of shavings can be seen. Δ: The presence of shavings can be seen at a glance. X: Shavings are badly attached.

[Example 1] (1) Production of silicone resin fine particles: 10 with stirring blade
A liter glass container is filled with 7000 g of an aqueous solution containing 0.2% by weight of sodium hydroxide, and 1000 is added to the upper layer.
After gently injecting g of methyltrimethoxysilane to form two layers, an interfacial reaction was carried out at 10 to 15 ° C. at a rotation speed of 20 rpm for 3 hours to generate particles. Thereafter, the temperature was set to 70 ° C., aging was carried out for 4 hours, cooling, filtration with a vacuum filter, and subsequent washing with 3000 g of water gave a cake of silicone resin fine particles having a water content of about 50%. The cake obtained was dried under reduced pressure at 90 ° C. and 15 Torr for 2 hours, and further dried under atmospheric pressure at 150 ° C. for 5 hours to obtain about 400 g of silicone resin fine particle powder.

Observation of the obtained fine particles with an electron microscope revealed that the particles had a true spherical shape, and the particle size distribution obtained by the centrifugal sedimentation method was 0.5% for 90% or more by weight.
Average particle size of 0.6 μm with uniform particle size within 0.7 μm
Of fine particles.

(2) Production of polyester containing no silicone resin fine particles: Using dimethyl terephthalate and ethylene glycol as raw materials, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, and a substant as a stabilizer are prepared by a conventional method. Intrinsic viscosity (orthochlorophenol, 35 ° C) 0.65 by polymerization reaction using phosphoric acid
Of polyester (polyethylene terephthalate) was obtained. The polyester had a Tg of 70 ° C. and a Tm of 257 ° C.

(3) Production of polyester composition containing fine particles of silicone resin: In FIG. 1, from a feed port 2 upstream of a vent type twin-screw kneading extruder 1 in which a kneading disk paddle is arranged as a kneading element, (2 ), The polyethylene terephthalate pellets having an intrinsic viscosity of 0.65 are fed at a rate of 30 kg / h using a vibrating quantitative feeder, and the silicone resin fine particles obtained in (1) are also fed from the feeding port 2 with a screw type. The polyethylene terephthalate pellets were supplied at a rate of 20 kg / h from a supply port 5 provided downstream of the extruder 1 using a vibrating metering feeder. The cylinder temperature is 260 ° C., the vacuum degree of the vent ports 4 and 6 is 1.
The polyethylene terephthalate composition containing 0.50% by weight of silicone resin fine particles was obtained by extruding at 0 mmHg and a shaft rotation speed of 100 rpm. The obtained polyester composition has an intrinsic viscosity of 0.62, Tg of 70 ° C. and Tm.
Was 257 ° C.

(4) Film formation of polyester composition:
Pellets of the polyester composition obtained in (3),
Polyester pellets having an intrinsic viscosity of 0.62 obtained by the same production method as in (2) are mixed so that the silicone resin fine particles account for 0.10% by weight based on the total weight of the polyester, and the mixture is mixed at 170 ° C. for 3 hours. After drying, it is fed to an extruder hopper and melted at a melting temperature of 280 to 300 ° C., and the molten polymer is passed through a slit die of 1 mm to have a surface temperature of 3
It was extruded on a rotary cooling drum at 0 ° C. and rapidly cooled to obtain an unstretched film.

The unstretched film thus obtained is preheated at 75 ° C., and further 15 m between low speed and high speed rolls.
m from above, heated by one IR heater having a surface temperature of 900 ° C., stretched to 3.6 times, rapidly cooled, then fed to a stenter, and stretched 3.7 times in the transverse direction at 105 ° C. .
The obtained biaxially oriented film was heat-set at a temperature of 205 ° C. for 5 seconds to obtain a heat-set biaxially oriented polyester film having a thickness of 15 μm.

In the production of the above unstretched film, a film-like molten polymer extruded from a die is
Static electricity was applied by an electrostatic application method in which a voltage of 6 KV was applied to the electrostatic wire to bring it into close contact with the drum. Immediately after the start of the film production (time 0) and after 1 hour, the current flowing through the electrostatic wire was measured, and the rate of decrease in current during this time was determined by the following formula to perform relative evaluation of electrostatic wire contamination.

[0055]

(Equation 3)

Table 1 shows the characteristics and the current reduction rate of the obtained film.

Comparative Example 1 (1) Production of Polyester Composition Containing Silicone Resin Fine Particles: Using dimethyl terephthalate and ethylene glycol as raw materials, manganese acetate as a transesterification catalyst and antimony trioxide as a polymerization catalyst were prepared by a conventional method. Was added with phosphorous acid as a stabilizer, and at the end of the transesterification reaction, the silicone resin fine particles obtained in (1) of Example 1 were sufficiently dispersed by a conventional method to prepare a 20% by weight ethylene glycol slurry. 0.10% by weight of fine particles corresponding to terephthalate was added, followed by a polymerization reaction to obtain an intrinsic viscosity (orthochlorophenol, 3
A polyester (polyethylene terephthalate) composition of 0.62 at 5 ° C. was obtained. The polyester has Tg70
C. and Tm 257.degree.

(2) Film formation of polyester composition:
17 pellets of the polyester composition obtained in (1)
After drying at 0 ° C. for 3 hours, it is fed to an extruder hopper and melted at a melting temperature of 280 to 300 ° C.
It was extruded onto a rotary cooling drum having a surface temperature of 30 ° C. through a slit die of m and rapidly cooled to obtain an unstretched film.

The unstretched film thus obtained was subjected to the same procedure as in Example 1 to obtain a biaxially oriented polyester film, and the electrostatic wire stain was evaluated.
Table 1 shows the results.

In Example 1, the film characteristics were satisfied, and the current reduction rate due to electrostatic wire contamination was as low as 1.8%, which was excellent, whereas in Comparative Example 1, the current reduction rate was 7.5%. The result was inferior.

[Examples 2 to 5, Comparative Examples 2 and 3] The same procedure as in Example 1 was carried out except that the average particle size of the silicone resin fine particles and the content in the film were changed. Table 1 shows the results.

In each of Examples 2 to 5, the film characteristics were satisfied, and the current reduction rate of the electrostatic wire was as low as 4% or less, which was good. Since either the particle size or the content is out of the range of the present invention, the film characteristics and / or the reduction rate of the electrostatic wire are inferior.

[Example 6] Of the polyester raw materials used in Example 1, 2,6 were used instead of zirtyl terephthalate.
—A polyester composition containing fine particles of silicone resin and a polyester not containing silicone particles were obtained in the same manner as in Example 1 except that dimethyl naphthalene dicarboxylic acid was used. Both of these polyesters have a Tg of 120 ° C and a Tm of
It was 267 ° C.

Subsequently, pellets of these polyesters (compositions) were mixed so that the silicone resin fine particles would be 0.10% by weight based on the total weight of the polyester, and the mixture was mixed at 170 ° C.
After drying for an hour, it is fed to the extruder hopper and melted at 2
It was melted at 90 to 310 ° C., and the molten polymer was extruded through a 1 mm slit die onto a rotary cooling drum having a surface temperature of 60 ° C. and rapidly cooled to obtain an unstretched film.

The unstretched film thus obtained is preheated at 130 ° C., and the roll is rolled at a low speed and a high speed for 15 minutes.
mm from above, heated by one IR heater having a surface temperature of 900 ° C., stretched 3.6 times, rapidly cooled, then supplied to a stenter, and stretched laterally 3.7 times at 135 ° C. . The obtained biaxially oriented film was heat set with hot air at 230 ° C. for 5 seconds to obtain a heat set biaxially oriented polyester film having a thickness of 15 μm.

The relative evaluation of the dirt on the electrostatic wires was carried out in the same manner as in Example 1.

[Comparative Example 4] Of the polyester raw materials in Comparative Example 1, 2,6 were used instead of dimethyl terephthalate.
-A polyester composition was obtained in the same manner as in Comparative Example 1 except that naphthalenedicarboxylic acid dimethyl ester was used. The polyester had a Tg of 120 ° C. and a Tm of 267 ° C.

Subsequently, the pellets of the polyester composition were dried at 170 ° C. for 3 hours, and then the same operation as in Comparative Example 1 was performed.

The results of Example 6 and Comparative Example 4 are shown in Table 1. Similar to Example 1 and Comparative Example 1, Example 6 satisfies the film characteristics and the electrostatic wire has a current reduction rate of 2%. .1
%, Which was low, and Comparative Example 4 had a poor current reduction rate of 8.5%.

[0070]

[Table 1]

[0071]

According to the present invention, it is possible to provide a polyester composition and a polyester film, which contain little electrostatic wire stain when formed into a film, and which are excellent in both slipperiness and abrasion resistance, containing a silicone resin fine particle.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a vent type twin-screw kneading extruder.

FIG. 2 is a schematic view of an apparatus for measuring a running friction coefficient (μk).

[Explanation of symbols]

 1 Cylinder and Screw 2 Supply Port 3 Supply Port 4 Vent Port 5 Supply Port 6 Vent Port 7 Constant Feeder 11 Unwinding Reel 12 Tension Controller 14 Tension Detector (Inlet) 17 Fixed Rod 20 Tension Detector (Outlet) 23 Take-up Reel

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08G 63/185 NNA C08G 63/185 NNA C08J 3/20 CFD C08J 3/20 CFDZ // (C08L 67 / 02 83:04) B29L 7:00

Claims (5)

[Claims] 1. A polyester having an average particle size of 0.05 to 3
A polyester composition in which 80% by weight or more of the particles are blended in a powder state with silicone resin fine particles having 80% by weight or more of the particles and having a bonding unit represented by the following formula, and kneaded with a vent-type twin-screw kneading extruder. Embedded image RSiO _3/2 (wherein R is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group.) 2. The polyester composition according to claim 1, wherein the amount of the silicone resin fine particles is 0.005 to 10% by weight based on the weight of the polyester. 3. The polyester composition according to claim 1, wherein the silicone resin fine particles are fine particles of substantially spherical polymethylsilsesquioxane. 4. The polyester composition according to claim 1, wherein the polyester is polyalkylene terephthalate or polyalkylene naphthalate. 5. A biaxially oriented polyester film using the polyester composition according to claim 1.