JPH06145391A - Polyester film - Google Patents

Abstract

PURPOSE:To obtain a polyester film excellent in surface uniformity, quality of traveling, scuff resistance and abrasion resistance. CONSTITUTION:A polyester film has on at least one surface thereof a coating layer provided in the course of production of the polyester film. The coating layer comprises 0.1-50wt.% aluminum oxide of at most 1mum in average particle size and 0.1-20wt.% lubricant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film having excellent running properties, electromagnetic conversion characteristics and abrasion resistance as a film for a magnetic recording medium. More specifically, the present invention relates to a base film suitable for high-density magnetic recording, in which the generation of scratches and abrasion powder during tape running is extremely small and the occurrence of dropout is suppressed.

[0002]

2. Description of the Related Art Polyester films have excellent physical and chemical properties and are widely used as industrial substrates. Among them, the biaxially oriented polyethylene terephthalate film is now indispensable as a base film for a magnetic recording medium because it is particularly excellent in mechanical strength, dimensional stability and flatness. Is being carried out at a rapid pace,
Along with this, the demands on the base film are becoming more severe. For example, in a video tape that requires high density recording, the magnetic layer is thinned. In this case, the unevenness of the base film itself is reflected on the surface of the magnetic layer. This leads to deterioration of conversion characteristics and frequent dropouts. Therefore, the surface of the base film is desired to be flatter, but when the surface of the film becomes flat, not only the running property of the film deteriorates, but also the friction and wear between the film and the base material, for example, the guide pin, are reduced. The film becomes large, and scratches are generated on the film, and abrasion powder is generated.

If the abrasion resistance of the polyester film is insufficient as described above, abrasion powder is generated between the film and various rolls or guide pins after the magnetic layer manufacturing process or product, and also the electromagnetic conversion characteristics. And will be inferior in terms of dropout. If the film has insufficient scratch resistance, the film is likely to be scratched before and after coating with the magnetic layer, which is reflected on the surface of the magnetic layer, resulting in poor electromagnetic properties. Further, the presence of the scraped white powder-like substance often deteriorates the electromagnetic characteristics.

As a means for improving surface properties such as running property and abrasion resistance of a polyester film, a method in which inert fine particles are present in the film to appropriately roughen the film surface, specifically, so-called precipitated particles Method and additive particle method are known.

The deposited particle method is a method of depositing catalyst residues and the like in the polyester as fine particles in the polyester production process. The operation is simple and the polymer can be produced at low cost, and the filter life during production is also increased. Has the advantage of being long. Furthermore, it has an excellent affinity with polyester, less particles fall off from the film, and relatively excellent abrasion resistance. However, since the main component of the deposited particles is an organic component, scratch resistance is poor.

On the other hand, the additive particle method is calcium carbonate,
This is a method in which fine particles of kaolin, silica, titanium oxide, etc. are added and contained during polyester production or molding. This method generally tends to lack the affinity between particles and polyester, but is known to be effective in improving scratch resistance. Particularly, as described in JP-A-1-306220, it is known that scratch resistance and abrasion resistance can be remarkably improved by using a specific amount of particles having high hardness.

However, in the method of blending high hardness particles into a polyester film, usually expensive particles obtained by a special production method must be filled in all layers of the film, and a polyester containing such particles is required. At the time of production, a large amount of ethylene glycol slurry having a low concentration must be added in order to improve the dispersion of the particles. Further, if the high hardness particles are filled in the entire layer of the film, the abrasion of the slit blade during the slitting of the film becomes significant, which is disadvantageous in terms of the apparatus and the operation, and hence the manufacturing cost.

[0008]

Means for Solving the Problems As a result of intensive investigations in view of the above problems, the present inventor has obtained a coating solution containing aluminum oxide particles and a lubricant in the production process of a polyester film. It was found that the film had excellent properties, and the present invention was completed. That is, the gist of the present invention is to have a coating layer provided on at least one surface of a polyester film in the film forming process of the polyester film, the coating layer containing aluminum oxide particles having an average particle diameter of 1 μm or less of 0.1 μm or less. A polyester film characterized by containing -50% by weight and 0.1-20% by weight of a lubricant.

The polyester used in the present invention for explaining the present invention in more detail below means an aromatic dicarboxylic acid such as terephthalic acid or 2.6-naphthalenedicarboxylic acid or an ester thereof and ethylene glycol as a main starting material. It refers to the obtained polyester, but may contain other third component. In this case, examples of the dicarboxylic acid component include isophthalic acid, terephthalic acid, and 2.
6-naphthalenedicarboxylic acid, adipic acid, sebacic acid and the like can be used. As the glycol component, diethylene glycol, propylene glycol, butanediol, 1.4-cyclohexanedimethanol, neopentyl glycol, etc. can be used. In any case, the polyester in the present invention refers to a polyester in which 80% or more of repeating structural units have ethylene terephthalate units or ethylene-2.6-naphthalate units.

The polyester film of the present invention refers to a polyester film using such polyester as a starting material, and a known method can be adopted as a manufacturing method thereof. For example, after melt-extruding into a sheet form at 270 to 320 ° C., cooling and solidifying at 40 to 80 ° C. to form an amorphous sheet, the area ratio becomes 4 to 20 times in the vertical and horizontal directions at 80 to 130 ° C. As described above, a method of performing sequential biaxial stretching or simultaneous biaxial stretching and heat treatment at 160 to 250 ° C. (for example, the method described in JP-B-30-5639) can be used. Stretching in the longitudinal and transverse directions may be carried out in one step each, and if necessary, it may be carried out in multiple steps or a heat treatment section for relaxing orientation may be provided during the multi-step drawing. Further, after biaxial stretching, it may be stretched again before being subjected to the heat treatment step of the next step. This re-stretching can be carried out in any of longitudinal and transverse directions.

The coating layer of the film of the present invention is applied to at least one side of the polyester film before the completion of stretching and heat treatment in the production process of the polyester film, followed by drying, stretching, heat setting and treatment of the polyester film. It is formed under conditions, and this method is usually called a coating and stretching method. Examples of the aluminum oxide particles used in the present invention include those produced by flame-type hydrolysis of anhydrous aluminum chloride or hydrolysis of aluminum alkoxide, and the average particle size of the primary particles thereof is preferably 1 μm or less, , And more preferably 0.2 to 0.005 μm. In the present invention, it is preferable to use the alumina particles by completely dispersing the particles up to the primary particles, but as long as it does not adversely affect the surface condition of the film, it may be agglomerated to some extent and behave as secondary particles. Also, a part of aluminum oxide,
For example, less than 30% by weight may be replaced by oxides such as Si, Ti, Fe, Na and K.

Regarding the particle size distribution of the aluminum oxide particles, a sharper one is preferable. Specifically, when integrated from the smaller particle size, the ratio of the particle size of 75% by weight to the particle size of 25% is usually 2. It is 0 or less, preferably 1.5 or less. As for the shape of these particles, those having a shape close to a lump or a sphere are preferably used. Specifically, for example, the volume shape defined in Japanese Patent Publication No. 53-14583 is 0.1 to π / 6, preferably 0.2 to π.
Particles such as / 6. The specific surface area of the particles used is, for example, an average particle diameter of 0.5 μm and a density of 2
A true spherical particle having g / cm ² has a specific surface area of about 6 m ² / g, but a porous particle having a specific surface area of about 500 m ² / g can be preferably used. The surface of these particles may be modified with various surface treatment agents for the purpose of improving the affinity with water-based paints.

In the present invention, these particles are used as one component of the coating agent, but in this case, they are dispersed in water in advance. At this time, it is desirable to use a small amount of a dispersant in order to improve the compounding stability with the aqueous resin. Further, if necessary, it is added to the coating solution through operations such as pulverization, classification and filtration. For example, aluminum oxide particles and water can be dispersed and adjusted using a high-speed stirrer having a plurality of shearing blades parallel to the rotating direction of the stirring blade, a homomixer, an ultrasonic disperser, or the like. Furthermore, the dispersed slurry is
It is desirable to filter with a cartridge type filter having 3 μm perforations for the purpose of removing coarse particles and undispersed agglomerated particles in the slurry.

The aluminum oxide used in the present invention is mixed in at least one resin selected from water-based urethane, water-based acrylic, water-based polyester and the like, which are usually used as a main binder, and coated on a polyester film. The amount of aluminum oxide is selected so that it falls within the range of 0.1 to 50% by weight, preferably 0.5 to 20% by weight. When the content of aluminum oxide in the coating layer is less than 0.1% by weight, the density of the aluminum oxide particles on the film surface becomes low, and the scratch resistance cannot be sufficiently improved. If the content of aluminum oxide in the coating layer exceeds 50% by weight, the mechanical strength of the coating layer will be poor.

The lubricant used in the present invention is an anionic surfactant, a cationic surfactant, an amphoteric surfactant, an amphoteric surfactant, a nonionic surfactant, a fluorine-based surfactant, an organic carboxylic acid and the like. Examples include derivatives, higher aliphatic alcohols, paraffins, waxes,
Especially preferred are polyolefin or silicone based lubricants.

As the polyolefin-based lubricant, waxes, resins and rubber-like substances which are homopolymers or copolymers of 1-olefin unsaturated hydrocarbons such as ethylene, propylene, 1-butene and 4-methyl-1-pentene , For example, polyethylene, polypropylene, poly-1-butene, poly-
An aliphatic dicarboxylic acid such as 4-methyl-1-pentene, an ethylene-propylene copolymer, azelaic acid and sebacic acid, an oxycarboxylic acid such as oxybenzoic acid and their ester-forming derivatives can be used.

As the silicone type lubricant, in addition to unmodified silicone such as dimethylpolysiloxane, fatty acid,
Any of polyether, alcohol, and silicone modified with a polar group such as an alkyl group can be used. Silicone modified with a polar group has a good affinity with the binder resin and is particularly preferable. In the present invention, the effect of easy slippage that a slight amount of the lubricating layer present in the surface layer of the coating film after stretching has the function of preventing the generation of scratches and abrasion powder when the polyester film travels in contact with a transport roll or the like. . This effect exerts a synergistic effect due to the presence of protrusions due to the aluminum oxide particles. Among the lubricants, there is a type that causes bleed-out, but this type is preferable because the compounding amount of the lubricant can be reduced.

The content of the lubricant in the coating layer is 0.1 to 2
It is 0% by weight. When the content of the lubricant is less than 0.1% by weight, the amount of the lubricant present on the surface layer of the coating film is too small to exert a sufficient lubricating effect. On the other hand, if it exceeds 20% by weight, the amount of the surface layer of the coating film is too large, which causes problems such as device contamination due to transfer of the coating layer.

The most effective anti-adhesion effect is exhibited when the lubricant present on the surface layer of the coating film is coordinated with the hydrophobic group on the outside. When the contact angle of water droplets, which is considered as a measure of the coordination state, is within the range of 70 to 85 degrees, the anti-adhesion effect is remarkably exhibited. The binder used in the coating layer of the present invention is usually a water-based resin, and the water-based resin referred to here means the manufacturing process of the magnetic recording material after being coated on the surface of the polyester film, or processing into the magnetic recording material. Mechanical strength, heat resistance, which can withstand the usage environment under high temperature and high humidity after
It is a resin that has moisture resistance and has excellent adhesiveness with an upper coating layer such as a magnetic layer or a back coat layer when this layer is used as an undercoat layer, and examples thereof include polyester, polyamide, polystyrene, and polyacryl -, Polycarbonate, polyarylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl butyral, polyvinyl alcohol, polyurethane and other resins and copolymers and mixtures of these resins, but are not limited to these It is not something that will be done. The most preferable resin among these is a polyester resin.

Examples of the component that constitutes the polyester resin include the following polyvalent carboxylic acids and polyvalent hydroxy compounds. That is, as the polycarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid,
Phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5
-Naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodiumsulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutar Acid, succinic acid, trimellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt and their ester-forming derivatives can be used. As the compound, ethylene glycol, 1,2-propylene glycol, 1,3
-Propylene glycol, 1,3-propanediol,
1,4-butanediol, 1,6-hexanediol,
2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p
-Xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, dimethylolethyl Sodium sulfonate, potassium dimethylolpropionate and the like can be used.

One or more of these compounds are appropriately selected and a polyester resin is synthesized by a conventional polycondensation reaction. In addition to the above, JP-A-1-165
The so-called acrylic grafted polyester described in Japanese Patent No. 633 and a composite polymer having a polyester component such as polyester polyurethane in which polyester polyol is chain-extended with isocyanate are also included in the polyester-based resin which can be used in the present invention.

The aqueous resin in the present invention may be a coating agent in which a liquid containing 70% by weight or more of water is used as a medium and forcedly dispersed by a surface active agent or the like, but preferably such as a polyether. It is a self-dispersion type coating agent having a hydrophilic nonionic component or a cationic group such as a quaternary ammonium salt, and more preferably a water-soluble or water-dispersible resin coating agent having an anionic group.

The resin having an anionic group is a resin having a compound having an anionic group bonded to the resin by copolymerization, grafting, or the like. Sulfonic acid, carboxylic acid, phosphoric acid and their lithium salts and sodium salts. , Potassium salt, ammonium salt and the like. The ratio of the anionic group to the coating solid content is 0.05 to 8% by weight.
Is preferred. If the amount of the anionic group is less than 0.05% by weight, the water solubility or water dispersibility of the resin tends to deteriorate, and if the amount of the anionic group exceeds 8% by weight, the water resistance and hygroscopicity of the coating layer are This can cause problems.

The coating solution for obtaining the coating layer in the present invention contains a methylol group or an alkyl group as a crosslinking agent in order to improve the adhesion (blocking property), water resistance, solvent resistance and mechanical strength of the coating layer. Rolled urea compounds, melamine compounds, guanamine compounds, acrylamide compounds, polyamide compounds, epoxy compounds, aziridine compounds, block polyisocyanates, silane coupling agents, titanium coupling agents, zirco-aluminate coupling agents, It may contain a peroxide, a heat- or photoreactive vinyl compound, a photosensitive resin, or the like. Further, if necessary, it may contain an antifoaming agent, a coating property improving agent, a thickening agent, an antistatic agent, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment, etc., and blend them. The effect of the present invention is sufficiently exerted even in such a system.

[0025]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The measuring methods and definitions of various physical properties and characteristics in the present invention are as follows. In addition, in Examples and Comparative Examples, "part"
"Parts by weight" means "parts by weight". (1) Average particle diameter The diameter (particle diameter) at an integrated volume fraction of 50% in the equivalent spherical distribution measured by the microscopic method was taken as the average particle diameter. (2) Center line average roughness (Ra) According to the method described in Japanese Industrial Standard JIS B0601, a surface roughness measuring instrument (SE- manufactured by Kosaka Laboratory Ltd.)
3F) was used to determine the centerline average roughness (Ra) and maximum height (Rt). The radius of the stylus used is 2.0μ
m, load is 30 mg, cut-off value is 0.08 m
m. (3) Slitting Polyester film with feather shaving blade (carbon steel double blade)
Using a blade holding angle of 30 degrees, fixed, slit speed 5
After slitting a total of 10,000 m under the condition of 00 m / min, the blade was observed with a microscope, and the degree of wear was judged according to the following evaluation criteria.

○: blade wear of less than 2 μm Δ: blade wear of 2 μm or more and less than 5 μm × ... blade wear of 5 μm or more

(4) Abrasion characteristics While contacting the film with the hard chrome fixing pin, 10
After running for 00 m, the abrasion white powder adhering to the fixed pin made of hard chrome was visually observed and evaluated according to the following criteria. The film speed was 13 m / min, the hearing was about 200 g, and the angle at which the film was sewn onto the pin was 135 °.

◎ ・ ・ ・ No white powder is generated ○ ・ ・ ・ White powder is generated in a very small amount △ ・ ・ ・ White powder is generated in a small amount × ・ ・ ・ White powder is generated in a large amount (5) Scratch resistance Polyester film is fixed pin made of hard chrome (Diameter 6
mm, surface roughness 3S), wrap angle 135 degrees, tension 20
They were contacted with each other at 0 g and run for 100 m at a speed of 13 m / min. Next, aluminum was vapor-deposited on the contact surface of the polyester film with the fixing pin, and the degree of scratches was visually evaluated and classified into the following ranks.

1 ... A large amount of scratches, often deep scratches 2 ... A relatively large amount of scratches, deep scratches in some places 3 ... A relatively small amount of scratches, few deep scratches 4 ... Slight scratches are observed, but satisfactory level 5 ... Small scratches

(6) Electromagnetic properties Magnetic fine powder 20 is applied to the non-coated surface of the polyester film.
0 parts, polyurethane resin 30 parts, nitrocellulose 10
Part, 10 parts of vinyl chloride / vinyl chloride copolymer, 5 parts of lecithin, 100 parts of cyclohexanone and 300 parts of methyl ethyl ketone are mixed and dispersed in a ball mill for 48 hours, and then 5 parts of a polyisocyanate compound is added to obtain a magnetic coating film after drying. After coating so as to have a thickness of 5 μm, the coating was magnetically oriented before being sufficiently dried and solidified, and then dried. Further, this coated film is surface-treated with a super calendar, and 1
A video tape was obtained by slitting a width of 1/2 inch. The following magnetic tape characteristics of this video tape were evaluated at a constant speed using an NV-3700 type video deck manufactured by Matsushita Electric Co., Ltd.

VTR head output (S / N ratio) The VTR head output at a measurement frequency of 4 MHz was measured by a synchroscope, the reference tape was 0.0 decibel (dB), and the relative value (dB) was the following reference. It was judged by. ○ ・ ・ ・ +2 dB or more △ ・ ・ ・ +0 dB to +2 dB × ・ ・ ・ +0 dB or less Number of dropouts (DO) 4, 4 MHz A video tape recorded with a signal is played back, and the number of dropouts is dropped by a dropout counter manufactured by Okura Industry. Was measured for about 20 minutes and converted into the number of dropouts per minute.

Comparative Example 1 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate were heated and heated, and methanol was distilled off to carry out a transesterification reaction, which required 4 hours from the start of the reaction. Then, the temperature was raised to 230 ° C. to substantially end the transesterification reaction. Then add 0.04 parts of ethyl acid phosphate,
Furthermore, 0.04 parts of antimony trioxide was added to carry out a polycondensation reaction, and after 4 hours and 30 minutes, polyethylene terephthalate having an intrinsic viscosity of 0.660 was obtained.

After drying the obtained polyester, 290 ° C.
Melt extruded to form an amorphous sheet, then 90 ° C in the machine direction
And draw it 3.5 times in the transverse direction and 3.7 times in the transverse direction at 110 ° C.
A heat treatment was performed at 0 ° C. for 3 seconds to obtain a film having a thickness of 15 μm. Comparative Example 2 Similar to Comparative Example 1 except that 0.3 part of aluminum oxide particles having an average particle diameter of 0.02 μm obtained by a thermal decomposition method was added at the time when the transesterification reaction was substantially completed. To obtain a polyethylene terephthalate film.

Example 1 After the longitudinal stretching of the polyester sheet of Comparative Example 1, the aluminum oxide particle-containing coating material shown below was applied by dry coating by a bar coating method so as to have a coating thickness of 0.05 μm, and then compared. A biaxially stretched polyethylene terephthalate film was obtained in the same manner as in Example 1.

Aluminum oxide particle-containing paint Aluminum oxide particles (pyrolysis method average particle size 0.02μ
m) 3 parts; polyethylene wax (Nopcoat PEM-17 manufactured by San Nopco) 1 part; polyester resin (Plus Coat Z-461 manufactured by Mutano Kagaku Co., Ltd.) 96 parts; water 900 parts

Example 2 A biaxially stretched polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the coating material containing aluminum oxide particles was changed to the one shown below. Oxidation
Paint containing aluminum particles Aluminum oxide particles (pyrolysis average particle size 0.02μ
m) 3 parts; polyethylene dispersion (High Tech E-4B manufactured by Toho Kagaku Co., Ltd.) 5 parts; polyester resin (Plus Coat Z-461 manufactured by Kyodo Chemical Co., Ltd.) 92 parts; water 900 parts Example 3 In Example 1, containing aluminum oxide particles. A biaxially stretched polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the paint was changed to the following. Oxidation
Paint containing aluminum particles Aluminum oxide particles (pyrolysis average particle size 0.02μ
m) 10 parts; polypropylene dispersion (Toho Kagaku Hitec E433N) 15 parts; polyester resin (Kyoso Chemical Plus Coat Z-461) 75 parts; water 900 parts

Comparative Example 3 A biaxially stretched polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the coating material containing aluminum oxide particles was changed to the one shown below. Oxidation
Paint containing aluminum particles Aluminum oxide particles (pyrolysis average particle size 0.02μ
m) 60 parts; Polyethylene wax (Nopcoat PEM-17 manufactured by San Nopco) 3 parts; Polyester resin (Plus Coat Z-461 manufactured by Kyodo Chemical Co., Ltd.) 37 parts; Water 900
Part Comparative Example 4 A biaxially stretched polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the aluminum oxide particle-containing coating material was changed to the one shown below. particle
Containing paint organic particles (polyacrylate average particle size 0.02μm)
3 parts; polyethylene wax (Nopcoat PEM-17 manufactured by San Nopco) 3 parts; polyester resin (Plus Coat Z-461 manufactured by Kyodo Chemical) 94 parts; water 900 parts

Comparative Example 5 A biaxially stretched polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the coating material containing aluminum oxide particles was changed to the one shown below. Oxidation
Paint containing aluminum particles Aluminum oxide particles (pyrolysis average particle size 0.02μ
m) 3 parts; polyester resin (Plus Coat Z-461 manufactured by Kyosho Chemical Co., Ltd.) 97 parts; water 900 parts Comparative Example 6 Similar to Example 1 except that the aluminum oxide particle-containing coating material is changed to the following one. To obtain a biaxially stretched polyethylene terephthalate film. Poly
Paint containing ethylene wax Polyethylene wax (Nopcoat PE manufactured by San Nopco
M-17) 3 parts; polyester resin (manufactured by Mutual Chemical Co., Ltd. Pluscoat Z-461) 97 parts; water 900 parts or more. The obtained results are summarized in Table 1 below.

[0039]

[Table 1]

The films of Examples 1 to 3 satisfying the requirements of the present invention are very excellent in running property and abrasion resistance, and particularly excellent in scratch resistance, and therefore have a highly satisfactory level in electromagnetic characteristics. On the other hand, Comparative Example 1 does not have the aluminum oxide particle-containing coating layer, and therefore has poor scratch resistance and inferior electromagnetic characteristics when used as a magnetic tape.
Comparative Example 2 is an example in which aluminum oxide particles are used as the internal particles of the polyethylene terephthalate film, but the slitability is poor and the workability is defective. Further, this method cannot be said to be a cost-effective method as described above. Comparative Example 3 is an example in which the content of aluminum oxide particles exceeds the requirements of the present invention, but the abrasion resistance is lowered due to the deterioration of the mechanical strength of the coating layer. Comparative Example 4 is an example in which organic particles are blended in place of aluminum oxide particles, and it can be seen that this particle does not have the effect of improving scratch resistance as much as aluminum oxide particles. Comparative Examples 5 and 6
Is an example in which aluminum oxide particles or a lubricant is used alone. Both of them show the effect of improving scratch resistance and abrasion resistance, but they do not show the high-level improvement effect of the examples.

[0041]

The film of the present invention has excellent abrasion resistance and scratch resistance, and its industrial value is high.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08L 67/02 LPL 8933-4J C09D 133/00 PFX 7921-4J 167/02 PKW 8933-4J 175 / 04 PHW 8620-4J G11B 5/704 7215-5D // B29K 67:00 B29L 7:00 4F 9:00 4F C08L 67:00 8933-4J

Claims (1)

[Claims] 1. A polyester film having a coating layer provided on at least one surface thereof during the step of forming the polyester film, the coating layer containing 0.1 to 50 parts by weight of aluminum oxide particles having an average particle size of 1 μm or less. % And a lubricant of 0.1 to 20% by weight, a polyester film.