JP2013071445A - Antistatic polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antistatic film which is manufactured easily, shows small temperature dependence and humidity dependence of antistaticity, and shows excellent slipperiness and blocking property during processing.SOLUTION: In the antistatic polyester film having an antistatic layer formed on at least one surface of a polyester film, the antistatic layer consists mainly of a polymer having a quaternary ammonium group and a carboxyl group in the side chain, and the surface roughness Sa of the surface of the antistatic layer is in the range of 0.06 to 0.2 μm.

Description

  The present invention relates to a polyester film having an antistatic layer on at least one surface, and is an antistatic film excellent in slipperiness even when used by sticking a sheet having adhesive properties such as self-adhesiveness and slight adhesiveness on the opposite surface, More particularly, the present invention relates to a polyester film useful for printing inks, adhesives, packaging materials such as photocurable resins and binders, information storage materials, building materials, printing materials, electronic materials and the like.

  Polyester film has excellent mechanical properties, heat resistance and transparency, and is widely used for packaging food applications and as base film and process film for industrial packaging materials, information storage materials, building materials, electronic materials, printing materials, etc. Has been. However, in general, plastic films and their laminated films are prone to static electricity due to contact friction and peeling during processing and product use, so dust and small dust are likely to adhere to them, so they are used as packaging materials for foods and pharmaceuticals. In addition, there is a problem that the suitability for paper feed and the suitability for paper discharge deteriorate during printing.

  Conventionally, as an antistatic method for a plastic film substrate, a charge neutralization method using ionized air, a mixture of an antistatic agent into a film resin (Patent Document 1), or a method by coating (Patent Document 2) are representative. Known as. However, if the surface condition of the film substrate is changed by these methods, the top and bottom of the wound roll will be blocked when the opposite surface is coated or printed in the industrial field, etc., destroying the coating or printing surface. May end up.

  In order to improve the above adverse effects, a polymer antistatic agent having an ionic group in the side chain has been proposed (Patent Document 3). This antistatic agent uses a polymer having a carboxyl group and an ammonium base in the side chain. Specifically, since chlorine ions are used as a counter ion, the heat resistance is not sufficient. For example, PVC In the heating process during use on the sheet and in the heating process during production of the stretched polyester film, there is a problem that the antistatic performance decreases due to thermal deterioration, and in the production of the polyester film, high heat is applied in the process of coating and drying and then setting the stretching heat. Therefore, there is a problem that free chlorine gas is generated and the equipment in the drawing machine is corroded for a long time. In addition, an antistatic agent having higher heat resistance using an alkyl sulfate ion as a counter ion has been proposed, but this has a problem that the stability of the coating liquid and the uniformity of the coating film are lacking during production. (Patent Document 4). In order to solve the above Patent Documents 1 to 4, an invention for forming a coating layer having excellent heat resistance and water resistance on at least one surface of a polyester film has been proposed (Patent Document 5), but a sticky sheet is pasted. When used together, the slipperiness was insufficient.

Japanese Patent Laid-Open No. 06-228366 JP 2002-265860 A Japanese Patent Application Laid-Open No. 07-252456 JP 2003-226866 A JP 2006-160883 A

  In view of these problems, the present invention intends to provide an antistatic film that is easy to manufacture, has low temperature dependency and humidity dependency of antistatic performance, and is excellent in slipping and blocking properties during processing. It is.

  As a result of diligent research, the present inventor has found that the above problem can be solved by applying a specific antistatic coating liquid to at least one surface of a polyester film surface having a specific surface roughness. Reached.

That is, the gist of the present invention is as follows.
(1) An antistatic polyester film having an antistatic layer on at least one side of a polyester film, wherein the antistatic layer is mainly composed of a polymer having a quaternary ammonium group and a carboxyl group in the side chain. The antistatic polyester film whose surface roughness Sa of the surface of a prevention layer is the range of 0.06-0.2 micrometer.
(2) The antistatic polyester film according to (1), wherein the surface roughness Sz of the antistatic layer is in the range of 6.0 to 8.0 μm.
(3) The antistatic polyester film according to (1) or (2), wherein the antistatic layer has a thickness of 0.05 to 0.5 μm.
(4) The antistatic polyester according to any one of (1) to (3), wherein the surface resistivity value at 23 ° C. and a relative humidity of 30% is in the range of 10 ⁸ to 10 ¹² Ω / □. the film.

  The antistatic polyester film of the present invention is excellent in coating film uniformity and antistatic properties, and is particularly excellent in slipperiness and blocking resistance even for materials having self-adhesiveness and slight adhesiveness. It is useful for applications that come in contact with self-adhesive or slightly adhesive materials such as information storage materials, building materials, printing materials, and electronic materials.

  Examples of the polyester used as the base material of the antistatic polyester film of the present invention include polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, and polyethylene phthalate is particularly preferable. In the present invention, other components may be copolymerized as necessary. However, when polyethylene terephthalate is mainly used, the melting point is preferably 230 to 256 ° C. When the melting point is 230 ° C. or lower, the crystallinity is lowered and the heat resistance may be poor.

The copolymer component is not particularly limited, but the acid component is isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, Examples include dodecanedioic acid, dimer acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and dicarboxylic acids such as cyclohexanedicarboxylic acid, 4-hydroxybenzoic acid, ε-caprolactone, and lactic acid.
The alcohol component includes ethylene glycol, diethylene glycol, 1,3-propanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol. Examples thereof include ethylene oxide adducts of A and bisphenol S.
Further, a small amount of trifunctional compounds such as trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane, glycerin, pentaerythritol, and the like may be used. Two or more of these copolymer components may be used in combination.

These polyesters are not limited in the polymerization method, and can be polymerized by, for example, a transesterification method or a direct polymerization method. Examples of the transesterification catalyst include Mg, Mn, Zn, Ca, Li, Ti oxides, acetates, and the like. Examples of the polycondensation catalyst include compounds such as Sb, Ti, Ge oxides and acetates.
Since the polyester after polymerization contains monomers, oligomers, by-products such as acetaldehyde, tetrahydrofuran and the like, it is preferable to carry out solid phase polymerization at a temperature of 200 ° C. or higher under reduced pressure or inert gas flow.

  In the polymerization of the polyester, additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, and an antistatic agent can be added as necessary. Examples of such antioxidants include hindered phenol compounds, hindered amine compounds, etc., thermal stabilizers such as phosphorus compounds, and ultraviolet absorbers such as benzophenone compounds and benzotriazole compounds. Can be mentioned.

  The polyester film used as a substrate in the present invention preferably has fine particles present in the film so as to have a predetermined surface roughness. The fine particles are selected from Group II, Group III, Group IV, etc. of the periodic table of elements such as kaolin, calcium carbonate, barium sulfate, silicon oxide, calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, etc. Inactive external particles composed of salts or oxides containing elements, high-melting-point organic compounds that are insoluble during the melt film formation of polyester resins, cross-linked polymers, and metal compound catalysts used during polyester synthesis, such as alkali metal compounds, alkaline earths Examples thereof include internal particles formed inside the polymer during the production of polyester by a metal compound or the like.

  The particle size and the amount of the fine particles can be appropriately selected, but the average particle size is preferably in the range of 2.0 to 5.0 μm, particularly preferably 2.5 to 4.5 μm. If the average particle size is smaller than 2.0 μm, the effect of improving the slipping property is small, and if the average particle size exceeds 5.0 μm, the transparency is inferior, the foreign matter defects are increased, and the effect of improving the slipping property is saturated. End up. The particle content is preferably 0.05 to 1.00% by weight. If the particle content is less than 0.05% by weight, the slipping property may be lost, and if it exceeds 1.00% by weight, the transparency may be inferior. is there.

  In the polyester film of the present invention, the surface roughness Sa (average deviation) of the antistatic layer needs to be 0.06 to 0.2 μm. When the Sa is less than 0.06 μm, the slipperiness is inferior when in contact with a self-adhesive or slightly adhesive material. May be roughened or the coating component may be transferred to the opposite surface. When Sa exceeds 0.2 μm, the slipping property and blocking property are improved, but the film surface is rough and the transparency of the film is lowered.

  In the polyester film of the present invention, the surface roughness of the antistatic layer is preferably in the range of 6.0 to 8.0 μm in Sz (10-point average height). If the thickness is less than 6.0 μm, the slipperiness with the film having slight adhesion and self-adhesion may be insufficient and blocking may occur, and if the thickness exceeds 8.0 μm, the surface irregularities are too large, Transparency may be impaired, or coarse aggregated foreign matter may be generated.

  The polyester film of the present invention must have an antistatic layer mainly composed of a polymer (A) having a quaternary ammonium group and a carboxyl group in the side chain on at least one side, and has an antistatic layer on both sides. May be.

  The polymer (A) having a quaternary ammonium group and a carboxyl group in the side chain may be any polymer (ion conducting polymer) having electrostatic polarization relaxation properties, and the quaternary in the polymer (A). The ammonium group can impart rapid electrostatic polarization relaxation due to electrostatic polarizability and ionic conductivity. The polymer (A) is preferably a polyacrylic copolymer having a quaternary ammonium group in the side chain and also having a carboxyl group in the side chain. Polyacrylic copolymer significantly improves properties such as adhesion, durability, and heat resistance due to the crosslinking reaction with the crosslinking agent, and the antistatic property effective for polyester film due to the electrostatic polarization relaxation performance of the polymer. Can be granted. As a specific example of the monomer constituting the polyacrylic copolymer, a monomer having a quaternary ammonium salt includes dimethylaminoethyl (meth) acrylate quaternized product having a counter ion of methyl sulfate or ethyl sulfate. In addition, examples of the monomer having a carboxyl group include (meth) acrylic acid, and examples of the other monomer include (meth) acrylic acid ester, styrene, and other vinyl derivatives. Although the composition ratio of these monomers can be varied within a wide range, the monomer having a quaternary ammonium group is preferably 15 to 25 mol% based on the total monomers of the copolymer, It is preferable that the monomer which has a carboxyl group is 5-10 mol%, and it is preferable that another monomer is 65-80 mol%. When the copolymerization amount of the monomer having a quaternary ammonium group or the monomer having a carboxyl group exceeds this range, the coating solution using the resulting polymer (A) has an increased viscosity, and the film becomes The coatability of the coating may deteriorate.

  In the present invention, when an alkyl sulfate ion is used as a counter ion, the quaternary ammonium salt is not easily decomposed by heat, and heat resistance can be imparted. Moreover, it is decomposed like chlorine ions, and chlorine gas is generated, so that there is no adverse effect such as corrosion of the metal contacting the laminated film. Specifically, when a high-temperature thermal head comes in contact with an antistatic heat-melting transfer ink ribbon having a primer layer with chlorine ions as counter ions, the thermal head may be corroded by chlorine gas generated by decomposition. is there. For example, a trimethylaminoethyl acrylate / chloride copolymer having a chlorine ion as a counter ion decomposes in 1 to 2 minutes when heated to 150 ° C. to generate chlorine gas, and the antistatic performance deteriorates. On the other hand, when a methyl sulfate salt is used as a counter ion, the surface specific resistance value hardly increases even when heated at 200 ° C. for 1 minute, and the antistatic performance is maintained.

  In addition to the polymer (A) having a quaternary ammonium group and a carboxyl group in the side chain, a crosslinking agent (B) and a surfactant (C) can also be added to the antistatic layer of the present invention. In particular, the addition of a crosslinking agent is preferable, and the cohesiveness and adhesion of the antistatic layer can be improved.

  As the crosslinking agent (B), an epoxy compound, a melamine resin, an isocyanate compound, a silane coupling agent, polyethyleneimine, polyvinyl alcohol and the like are preferable. In the present invention, it is more preferable to use two or more kinds selected from these in combination. When the crosslinking agent is one type, the cohesiveness / adhesiveness of the coating film is insufficient, and the seal bar may be removed. In addition, it is preferable that a crosslinking agent (B) is water-soluble or water-dispersible in order to apply to a polyester film, without using an organic solvent.

  The epoxy compound is preferably a bifunctional derivative such as diethylene glycol diglycidyl ether, glycerin diglycidyl ether, or bisphenol A diglycidyl ether, or a trifunctional derivative such as trimethylolpropane triglycidyl ether. In addition, since the residual of a chlorine ion is unavoidable from the relationship which uses epichlorohydrin for a raw material, the epoxy compound from which the chlorine ion was removed as much as possible is desirable.

  The melamine resin is preferably selected from trimethylol melamine, hexamethylol melamine, trismethoxymethyl melamine, hexakismethoxymethyl melamine and the like.

  Examples of the isocyanate compound include aromatic polyisocyanates such as toluene diisocyanate and diphenylmethane diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, cyclohexane diisocyanate, and butane diisocyanate, and derivatives thereof. A blocked isocyanate compound is preferable in terms of enhancing the stability of the coating solution.

  Examples of the silane coupling agent include epoxy alkyl silanes and aminoalkyl silanes, and γ-glycidoxypropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, and the like are preferable.

  Examples of the polyethyleneimine include highly polar and high density polyamines having a branched structure composed of primary, secondary, and tertiary amines. In addition, examples of the water-soluble resin include a polyvinyl alcohol resin, and the polyvinyl alcohol resin preferably has a saponification degree of 89% or more and a molecular weight of 100 to 1,000.

  The mass ratio (A / B) between the polymer (A) and the crosslinking agent (B) is preferably 95/5 to 70/30, and more preferably 90/10 to 80/20. If the crosslinking agent (B) is less than 5%, the adhesion may not be good, and if it exceeds 30%, the antistatic performance may be deteriorated.

  In addition, as a catalyst for the crosslinking agent (B), an imidazole derivative such as 2-methylimidazole and 2-ethyl-4-methylimidazole, an epoxy ring-opening reaction catalyst such as a polyamine and a polyethyleneimine derivative, and a melamine such as valatoluenesulfonic acid Crosslinking catalysts, catalysts for urethane crosslinking such as imidazole and organotin compounds may be used. The amount of these catalysts is not particularly limited, but is preferably 5 to 30% by mass, particularly 5 to 15% by mass, based on the total mass of the polymer (A) and the crosslinking agent (B).

  The surfactant (C) is added in order to bring out the antistatic performance of the polymer (A) having electrostatic polarization relaxation properties to a higher degree, and in particular to stabilize the antistatic property without depending on humidity. Preferably, it is a low molecular ion conduction type surfactant. Specifically, it can be selected from general anionic surfactants, cationic surfactants, and nonionic surfactants. In particular, a compound having a quaternary ammonium salt and a compound having a sulfonate are preferable from the viewpoint of compatibility with the coating liquid, coating suitability, adhesion, and blocking resistance. The addition amount of the surfactant (C) is desirably 1 to 10 parts by mass and more preferably 1 to 5 parts by mass with respect to 100 parts by mass in total of the polymer (A) and the crosslinking agent (B). preferable. When the addition amount is less than 1 part by mass, the antistatic effect is not sufficient, and when it exceeds 10 parts by mass, the adhesion may be impaired or the surface opposite to the coated surface of the substrate film may be contaminated.

  The thickness of the antistatic layer of the polyester film of the present invention is preferably 0.05 to 0.5 μm. If the thickness of the antistatic layer is less than 0.05 μm, the antistatic performance may not be exhibited. If the thickness exceeds 0.5 μm, the antistatic performance is saturated and the coating viscosity is set high, resulting in poor appearance. It becomes easy.

The surface specific resistance value of the polyester film of the present invention is preferably 10 ⁸ to 10 ¹² Ω / □ at 23 ° C. and a relative humidity of 60%. Furthermore, it is preferably 10 ⁸ to 10 ¹² Ω / □ even at 23 ° C. and a relative humidity of 30%, which are lower humidity conditions. When the surface specific resistance value exceeds 10 ¹² Ω / □, the antistatic performance is insufficient. It is particularly preferable that the above two conditions are in the range of 10 ⁸ to 10 ¹² Ω / □ because the performance dependence due to the use environment is reduced.

  Regarding the slipperiness of the antistatic layer surface of the polyester film of the present invention, it is preferable that the friction coefficient A under the conditions described later when the counterpart material is a polyester film is less than 0.36. Furthermore, it is preferable that the friction coefficient B under the conditions described later when the counterpart material is a predetermined adhesive material is less than 2.0. When the friction coefficients A and B are each equal to or greater than the predetermined value, the films block each other, and defects are likely to occur in the unwinding and winding processes.

  A known method may be adopted as a method for producing the film of the present invention. For example, a polyester resin is melt-extruded into a sheet form at 250 to 320 ° C., then cooled and solidified at 10 to 80 ° C. to form an amorphous sheet, and then biaxially or simultaneously stretched in the longitudinal and transverse directions, 160 A method such as heat treatment at ˜250 ° C. can be used. When stretching in the longitudinal and transverse directions, each may be stretched in one step, and if necessary, stretching may be performed in multiple steps, or a heat treatment section for orientation relaxation may be provided between the multiple steps. Further, after biaxial stretching, the film may be stretched again before being subjected to the heat treatment step of the next step. This re-stretching can be performed in either the vertical or horizontal direction, or in both directions.

In the present invention, the coating liquid for forming the antistatic layer can of course be applied to the base film after stretching, but can also be applied in the manufacturing process of the base film, In the latter method, the drying and curing reactions can proceed simultaneously with the stretching and heat setting treatments. As the stretching method, both simultaneous biaxial stretching and sequential biaxial stretching are possible, and it is preferable to apply before stretching in simultaneous biaxial stretching and after longitudinal stretching in sequential biaxial stretching, and if necessary before stretching after coating. It is preferable to provide a preliminary drying step. The method of applying the coating liquid to the film can be a general coating method, such as Mayer bar coat, air knife coat, reverse roll coat, reverse gravure roll coat, gravure roll coat, lip coat, die coat, etc. The method is mentioned. The coating liquid application amount is preferably 1 to 10 g / m ² . The drying conditions after coating are preferably 50 to 90 ° C. and 10 to 60 seconds. When the film is stretched after coating and drying, the stretching temperature is preferably 110 to 130 ° C. and the stretching ratio is preferably 3 to 10 times. Further, when heat treatment is performed after stretching, the heat treatment temperature is preferably 220 to 240 ° C. and the time is preferably 5 to 15 seconds.

  The antistatic polyester film of the present invention can also be made into a laminated film by laminating adhesive sheets. In this case, when the roll is wound or stacked, the antistatic layer and the pressure-sensitive adhesive sheet layer have an appropriate slipperiness, so that the workability is excellent.

  EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to only these examples. Evaluation methods used in Examples and Comparative Examples are shown below.

Three-dimensional roughness measurement:
The surface average deviation Sa and the 10-point average height Sz were measured with a precision non-contact three-dimensional roughness measuring instrument manufactured by Taylor Hobson.

Friction coefficient A:
Partner material PET film (Embret made by Unitika, thickness 16 μm, Sa = 0.06 μm, Sz = 5.3 μm)
Using a Friction Tester manufactured by Toyo Seiki Co., Ltd., the sample polyester film was allowed to stand for 3 hours at a temperature of 23 ° C. and a relative humidity of 60% according to the friction test of JIS K7125, and the friction coefficient of the antistatic layer surface was measured. .

Friction coefficient B:
Opposite material Sanei Kaken Co., Ltd. multilayer film PAC-3-60 (multilayer film having polyethylene layer as base layer and ethylene vinyl alcohol layer as adhesive layer)
According to the friction test of JIS K7125 except that the weight of the test piece was measured at 400 g using a Friction Tester manufactured by Toyo Seiki Co., Ltd. The sample polyester film was allowed to stand for 3 hours at a temperature of 23 ° C and a relative humidity of 60%. Thereafter, the coefficient of friction between the adhesive layer surface of the counterpart material and the antistatic layer surface of the sample film was measured.

Haze (Hz):
According to JIS-K-7105-1981, the turbidity of the film was measured with a Nippon Denshoku Industries turbidimeter. Practically, it is preferably 10% or less.

Coating uniformity:
White light was applied from an angle of 5 ° to 45 ° with respect to the surface of the antistatic layer of the antistatic polyester film, and the presence or absence of coating omission or coating unevenness was examined.
○: No coat omission or spots Δ: Fine coat omission or spots ×: Frequent coat omission or spots

Surface resistivity:
After the polyester film is left and conditioned for 3 hours at a temperature of 23 ° C. and a relative humidity of 60%, the surface after an applied voltage of 500 V-10 seconds is measured at the same temperature and humidity using a high resistance meter HT-260 measuring instrument manufactured by Dia Instruments. The specific resistance value (Ω / □) was measured.

Example 1
(Coating solution preparation)
As a polymer (A), (methyl methacrylate / ethyl acrylate / acrylic acid / dimethylaminoethyl methacrylate methyl sulfate quaternized product copolymerized at a mass ratio of 45/5/5/45, solid content concentration 30 mass %) 28.3 kg (solid content 8.5 kg) was used, and polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., P-1000, solid content concentration 30 mass%) 1.7 kg (solid content 0) was used as the crosslinking agent (B). 0.5 kg) was added and stirred thoroughly with a propeller stirrer. Next, 1 kg of epoxy compound (Nagase Kasei Kogyo Co., Ltd., Denacol EX1610, solid content concentration 100% by mass) as a second type of cross-linking agent (B) (solid content 1 kg) is added. 1.0 kg (solid content 1 kg) of Olphine E-1004 (solid content concentration 100% by mass) manufactured by Shin Kagaku Corporation was added and stirred for 60 minutes. Subsequently, it was diluted with pure water to adjust the total solid content concentration to 15% by mass, and after stirring for 30 minutes, it was stopped and degassed to obtain a coating solution.

(Production of film and formation of antistatic layer)
Polyethylene terephthalate containing 0.3% by mass of amorphous silica particles having an average particle diameter of 4.0 μm (relative viscosity 1.38 (temperature: 20 ° C., solvent: phenol / tetrachloroethane = 50/50, concentration: 0.5 g / dl) is melt-extruded at 280 ° C., and is tightly cooled to the casting drum by T-die method-electrostatic pinning method to form an unstretched film having a thickness of 260 μm. The film was stretched 3.5 times with a stretching roll, and the longitudinally stretched film was coated on the one side of the film using a reverse clavia coater so that the coating amount was 5 g / m ^2. The film was stretched 4.5 times at 120 ° C., heat-treated at 230 ° C. for 10 seconds, cooled and wound up, and the resulting antistatic polyester film had a thickness of 18 μm. Stop layer was about 0.15 [mu] m. The surface roughness of the stretched film Sa is 0.13 [mu] m, Sz was 6.8 [mu] m. The performance evaluation of this film, the results are shown in Table 1.

Examples 2 and 5 and Comparative Examples 2 and 3
In Example 1, the content of amorphous silica particles having an average particle size of 4.0 μm was 0.15 mass% (Example 2), 0.38 mass% (Example 5), 0.11 mass% (Comparative Example) An antistatic polyester film was obtained by coating and coating in the same manner as in Example 1 except that polyethylene terephthalate at 2) or 0.45% by mass (Comparative Example 3) was used.

Examples 3 and 4 and Comparative Example 1
In Example 1, in place of the amorphous silica particles having an average particle diameter of 4.0 μm, 2.0 μm of amorphous silica particles were 0.30 mass% (Example 3) and 0.38 mass% (Example 4). Alternatively, an antistatic polyester film was prepared in the same manner as in Example 1 except that polyethylene terephthalate containing 0.15% by mass (Comparative Example 1) was used.

  The films obtained in Examples 1 to 5 are excellent in three-dimensional surface roughness, friction coefficient, Hz, coating film uniformity, surface resistivity, and no reduction in antistatic performance due to humidity change. It was.

In Comparative Example 1, since the amorphous silica particles had a small particle size and a small addition amount, the friction coefficient was higher than that of the antistatic polyester film of the example, and the slipperiness was poor.
In Comparative Example 2, the size of the amorphous silica particles was suitable, but the amount added was small and the slipperiness was poor.
Although Comparative Example 3 was excellent in slipperiness, the surface roughness was too large and the Hz value was poor.

Claims (4)

An antistatic polyester film having an antistatic layer on at least one side of the polyester film, wherein the antistatic layer is mainly composed of a polymer having a quaternary ammonium group and a carboxyl group in the side chain, and the surface of the antistatic layer An antistatic polyester film having a surface roughness Sa of 0.06 to 0.2 μm. The antistatic polyester film according to claim 1, wherein the surface roughness Sz of the antistatic layer is in the range of 6.0 to 8.0 µm. The antistatic polyester film according to claim 1 or 2, wherein the antistatic layer has a thickness of 0.05 to 0.5 µm. The antistatic polyester film according to any one of claims 1 to 3, wherein a surface specific resistance value at 23 ° C and a relative humidity of 30% is in a range of 10 ⁸ to 10 ¹² Ω / □.