Laminated polyester film and method for producing the same

Abstract

To provide a laminated polyester film which is excellent in abrasion resistance and antistatic property.SOLUTION: A laminated polyester film has a resin layer (X) containing an acrylic resin (A) and a methacrylate-styrene copolymer compound (B), on at least one surface of the polyester film.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated polyester film and a method for producing the same. [Background technology]

[0002] Thermoplastic resin films, especially biaxially oriented polyester films, have excellent mechanical properties, electrical properties, dimensional stability, transparency, chemical resistance, and other properties, and are therefore widely used in many applications such as magnetic recording materials and packaging materials.

[0003] In recent years, there has been an increasing demand for films with excellent antistatic properties, blocking resistance, and abrasion resistance, which are used as protective films and carrier films in the processing of various electronic components.

[0004] However, because polyester is generally an insulating resin, biaxially oriented polyester films lack antistatic properties as they are. Antistatic properties are imparted to prevent foreign matter defects caused by dust adhesion due to static electricity. For example, antistatic properties can be imparted by neutralizing the charge imbalance by imparting conductivity to the surface or inner layer of an insulating material such as a biaxially oriented polyester film. Among these methods, the application of a conductive coating layer to the surface of a polyester film provides an easy way to maintain the various stable properties of the film, and various methods have been investigated. Furthermore, methods using a resin containing a wax component (Patent Document 1) and a film containing a long-chain alkyl resin (Patent Document 2) have been investigated to achieve excellent abrasion resistance. However, these methods did not provide sufficient slip resistance, resulting in poor abrasion resistance when used as a carrier film.

[0005] Furthermore, in order to improve the antistatic performance, a method has been proposed in which a polythiophene-based conductive agent, which is an electron-conductive antistatic agent, is used in combination with a polystyrene sulfonate-based antistatic agent (Patent Document 3). Furthermore, an inexpensive antistatic film has been investigated that uses an acrylic resin in combination with an antistatic material having a sulfonate group (Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-113528 [Patent Document 2] International Publication No. 2020 / 255755 [Patent Document 3] Japanese Patent Publication No. 2022-176956 [Patent Document 4] Japanese Patent Application Publication No. 10-119218 Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, which uses an antistatic agent and wax, and Patent Document 3, which is an improvement on the former and contains a phosphate ester, although they have abrasion resistance, the wax and phosphate ester bleed out, resulting in a problem of poor antistatic properties. Furthermore, in order to improve antistatic properties, a polythiophene-based conductive agent, which is an electron-conductive type antistatic agent, and a polystyrene sulfonic acid-based antistatic agent are used in combination (Patent Document 3), which poses a problem of high costs.

[0008] An object of the present invention is to overcome the above drawbacks and to provide a laminated polyester film having excellent abrasion resistance and antistatic properties. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention has the following configuration.

[0010] (1) A laminated polyester film having a resin layer (X) containing an acrylic resin (A) and a methacrylic acid ester-styrene copolymer compound (B) on at least one side of a polyester film.

[0011] (2) A laminated polyester film having a resin layer (X) on at least one side of a polyester film, wherein the surface of the resin layer (X) has a peak density Spd of 300 or more and 1500 or less, and a mean curvature of the protrusions Spc of -500 or more and -100 or less.

[0012] (3) The surface resistivity R1 of the resin layer (X) is 1.0 × 10 8 Ω / □ or more 1.0×10 11 The laminated polyester film according to (1) or (2), wherein the surface resistivity R2 is less than Ω / □ and the ratio (R2 / R1) to the surface resistivity R2 after an abrasion test is 2.0 or less. [Wear test conditions] The resin layer (X) surface of the laminated polyester film is subjected to a load of 20 g / cm 2 The sample is rubbed back and forth 10 times using a nonwoven fabric (Haise Gaze NT-4 manufactured by Ozu Sangyo Co., Ltd.).

[0013] (4) The laminated polyester film according to any one of (1) to (3), which has a haze of 10% or less.

[0014] (5) A laminated polyester film according to any one of (1) to (4), in which the haze change calculated by the following formula, where H1 is the haze before the abrasion test and H2 is the haze after the abrasion test, is 2% or less. Haze change (%) = |H2-H1| [Wear test conditions] The resin layer (X) surface of the laminated polyester film is subjected to a load of 20 g / cm 2 The sample is rubbed back and forth 10 times using a nonwoven fabric (Haise Gaze NT-4 manufactured by Ozu Sangyo Co., Ltd.).

[0015] (6) The laminated polyester film according to any one of (1) to (5), wherein the surface free energy of the resin layer (X) is 40 mN / m or more and 60 mN / m or less.

[0016] (7) A laminated polyester film according to any one of (1) to (6), containing inorganic or organic particles having a number average particle diameter of 0.01 μm to 5 μm in an amount of 0.01% by mass to 2.00% by mass based on the entire laminated polyester film.

[0017] (8) The laminated polyester film according to any one of (1) to (7), wherein the resin layer (X) contains substantially no inorganic particles or organic particles.

[0018] (9) The laminated polyester film according to any one of (1) to (8), characterized in that the laminated polyester film does not contain an organic fluorine compound in an amount of 50 ppm or more. (10) The laminated polyester film according to any one of (1) to (9), which is used in the production process of electronic components, battery components, or semiconductor components.

[0019] (11) The laminated polyester film according to any one of (1) to (10), which contains at least one of a biomass raw material and a recycled raw material.

[0020] (12) A method for producing a laminated polyester film according to any one of (1) to (11), comprising: a melt extrusion step of forming a polyester film containing one or more inorganic particles or organic particles; and a step of applying a coating composition containing an acrylic resin (A) and a methacrylic acid ester-styrene copolymer compound to the surface of the polyester film, followed by stretching and heat treatment in at least one direction to form a resin layer (X). [Effects of the Invention]

[0021] The laminated polyester film of the present invention is characterized by its excellent antistatic properties and its resistance to deterioration due to abrasion during transportation in the processing steps. DETAILED DESCRIPTION OF THE INVENTION

[0022] The laminated polyester film of the present invention will be described in detail below.

[0023] In one embodiment of the present invention, the laminated polyester film of the present invention has, on at least one surface thereof, a resin layer (X) containing an acrylic resin (A) and a methacrylic acid ester-styrene copolymer compound (B).

[0024] A suitable method for forming the resin layer (X) of the present invention is to apply a coating composition containing an acrylic resin (A) and a methacrylic acid ester-styrene copolymer compound, particularly a water-based coating composition, to a substrate.

[0025] As the resin having an acrylic resin skeleton used in the coating composition for forming the resin layer (X), for example, an acrylic resin emulsion dispersed in water can be used.

[0026] [Acrylic resin] The monomer component constituting the acrylic resin (A) used in the coating composition for forming the resin layer (X) is not particularly limited, and examples thereof include alkyl acrylates, alkyl methacrylates (the alkyl group may be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, a lauryl group, a stearyl group, a cyclohexyl group, a phenyl group, a benzyl group, a phenylethyl group, etc.), hydroxy group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylacrylamide, N-methylpropional ... Amide group-containing monomers such as N-methylolmethacrylamide, N-methylolmethacrylamide, N,N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, and N-phenylacrylamide; amino group-containing monomers such as N,N-diethylaminoethyl acrylate and N,N-diethylaminoethyl methacrylate; epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; and carboxyl group- or salt-containing monomers such as acrylic acid, methacrylic acid, and salts thereof (lithium salt, sodium salt, potassium salt, etc.). These may be copolymerized using one or more of these. Furthermore, these may also be used in combination with other types of monomers.

[0027] Examples of other monomers that can be used include epoxy group-containing monomers such as allyl glycidyl ether, carboxyl group- or salt-containing monomers such as crotonic acid, itaconic acid, maleic acid, fumaric acid, and salts thereof (lithium, sodium, potassium, ammonium, etc.), acid anhydride-containing monomers such as maleic anhydride and itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl chloride, vinyl acetate, etc. Modified acrylic copolymers, such as block copolymers and graft copolymers modified with polyester, urethane, or epoxy, can also be used.

[0028] Preferred acrylic resins for use in the resin layer (X) of the laminated polyester film of the present invention include copolymers selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide, and acrylic acid. The polymerization method for the acrylic resin emulsion of the present invention is not particularly limited, but emulsion polymerization, suspension polymerization, etc. are usually preferred.

[0029] In a more preferred embodiment of the present invention, functional groups such as carboxyl, hydroxyl, methylol, and amide groups can be introduced into the acrylic resin by copolymerization, and then a material capable of crosslinking with the functional groups can be mixed. In this case, the use of the specific acrylic resins described above increases the reaction efficiency with the crosslinking agent, thereby improving the water resistance and heat resistance of the laminated film. The type of crosslinking agent is not particularly limited as long as it crosslinks with the functional groups described above. Examples of crosslinking agents that can be used include melamine-based crosslinking agents, oxazoline-based crosslinking agents, carbodiimide-based crosslinking agents, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, methylolated or alkylolated urea-based, acrylamide-based, polyamide-based resins, amide-epoxy compounds, various silane coupling agents, and various titanate-based coupling agents. Carbodiimide-based crosslinking agents and oxazoline-based crosslinking agents are particularly preferred.

[0030] The resin layer (X) of the present invention can be endowed with excellent water absorption (hydrophilicity) by containing a methacrylate ester-styrene copolymer compound, and the resin layer (X) has excellent electrical conductivity due to its high moisture content, resulting in excellent antistatic properties. Note that "antistatic properties" includes not only preventing static electricity but also reducing static electricity.

[0031] [Methacrylate-styrene copolymer] The monomer components constituting the methacrylic acid ester-styrene copolymer compound used in the coating composition for forming the resin layer (X) are not particularly limited, and examples thereof include acrylic monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, tridecyl (meth)acrylate, lauryl ( Examples of suitable acrylic monomers include alkyl (meth)acrylates such as dodecyl (meth)acrylate and stearyl (meth)acrylate; alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and adamantanyl (meth)acrylate; nitrogen-containing (meth)acrylic monomers such as (meth)acrylonitrile, (meth)acrylamide, and diacetone (meth)acrylamide; acrylic acid; and methacrylic acid. (Meth)acrylate refers to acrylate or methacrylate. (Meth)acrylic refers to acrylic or methacrylic. The acrylic monomers may be used alone or in combination. Styrene-based monomers include styrene, α-methylstyrene, p-methylstyrene, Examples include methylstyrene, tert-butylstyrene, chlorostyrene, vinyltoluene, etc., and styrene is preferred from the viewpoint of abrasion resistance. The styrene-based monomers may be used alone or in combination of two or more.

[0032] [Resin layer (X) composition] Preferred coating compositions for forming the resin layer (X) of the laminated polyester film of the present invention will be explained in more detail below.

[0033] In one embodiment of the present invention, the coating composition for forming the resin layer (X) of the laminated polyester film of the present invention may be a coating composition containing an acrylic resin (A) and an ethyl methacrylate-styrene copolymer compound (B). This composition improves the dispersibility of the components in the coating composition, thereby improving the antistatic properties and abrasion resistance of the resulting laminated polyester film.

[0034] In the coating composition for forming the resin layer (X), the acrylic resin (A) is preferably 10% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 65% by mass or less, and even more preferably 10% by mass or more and 60% by mass or less, relative to 100% by mass of the total solids content of the coating composition. Having the acrylic resin (A) at 10% by mass or more ensures the film-forming properties of the coating film and improves the transparency of the resulting laminated polyester film. On the other hand, having the acrylic resin (A) at 70% by mass or less makes it easy to achieve sufficient antistatic properties. When multiple types of acrylic resin (A) are contained, the content is the combined value of all acrylic resin components.

[0035] The content of the methacrylate ester-styrene copolymer compound (B) in the resin layer (X) is preferably 30% by mass or more and 90% by mass or less relative to the total resin layer. A content of the methacrylate ester-styrene copolymer compound (B) of 30% by mass or more can favorably improve the antistatic properties, mechanical strength, and abrasion resistance of the resin layer (X), making this a preferred embodiment. Furthermore, a content of the methacrylate ester-styrene copolymer compound (B) of 90% by mass or less improves the wettability, resulting in a uniform resin layer (X), and favorable antistatic properties. The content of the methacrylate ester-styrene copolymer compound (B) is more preferably 35% by mass or more and 90% by mass or less, and even more preferably 40% by mass or more and 80% by mass or less. Furthermore, a surfactant may be added to the coating composition for forming the resin layer (X) to improve wettability. The surfactant used in the resin layer (X) is not particularly limited, but it is preferable that it does not contain an organic fluorine compound from the perspective of environmental friendliness.

[0036] In addition, from the viewpoint of improving abrasion resistance and haze, it is preferable that the resin layer (X) contains substantially no organic particles or inorganic particles. The measurement method will be described later.

[0037] By setting the ratio of the coating composition forming the resin layer (X) of the laminated polyester film of the present invention within the above-mentioned range, the surface free energy of the resin layer (X) can be set to 40 mN / m or more and 60 mN / m or less. Setting the surface free energy of the resin layer (X) to 40 mN / m or more improves handling properties, and is advantageous in that it suppresses the occurrence of winding slippage and winding defects during the production of the laminated polyester film. Furthermore, setting the surface free energy to 60 mN / m or less can suppress the occurrence of unwinding defects and transport defects during the production of carrier tape. A surface free energy of 40 mN / m or more and 55 mN / m or less is more preferable.

[0038] In one embodiment of the invention, from the viewpoint of abrasion resistance, the laminated polyester film of the present invention has a peak density Spd of 300 or more and 1500 or less and a mean curvature of protrusions Spc of -500 or more and -100 or less on the surface of the resin layer (X). When the peak density Spd is 300 or more and the mean curvature of protrusions Spc is -500 or more, good abrasion resistance can be achieved. It is more preferable that the peak density Spd is 350 or more and 1500 or less and the mean curvature of protrusions Spc is -500 or more and -150 or less, and it is even more preferable that the peak density Spd is 400 or more and 1500 or less and the mean curvature of protrusions is -500 or more and -200 or less.

[0039] As a method for adjusting the peak density Spd and the average curvature Spc of the protrusions on the surface of the resin layer (X) to fall within the above-mentioned ranges, an embodiment in which inorganic particles or organic particles having a suitable number average particle diameter, as described below, are contained in a suitable proportion throughout the entire laminated polyester film can be mentioned.

[0040] The laminated polyester film of the present invention preferably contains 0.01% by mass or more and 2.00% by mass or less of inorganic or organic particles having a number-average particle diameter of 0.01 μm to 5 μm, based on the entire laminated polyester film. When the number-average particle diameter is 5 μm or less, the abrasion resistance of the laminated polyester film is favorable. The lower limit of the number-average particle diameter is substantially 0.01 μm or more. Furthermore, when the content of inorganic or organic particles is 2.00% by mass or less, the haze value of the laminated polyester film is favorable, making it suitable for use as a cover tape for electronic components. The lower limit of the content of inorganic or organic particles is substantially 0.01% by mass or more. The number-average particle diameter of the inorganic or organic particles contained in the entire polyester is more preferably 0.01 μm to 3 μm, and even more preferably 0.01 μm to 2 μm. From the viewpoint of transparency when the laminated polyester film is formed, the inorganic or organic particles are preferably contained in an amount of 0.01% by mass or more and 1.5% by mass or less, and more preferably 0.01% by mass or more and 1.0% by mass or less. Note that the number average particle size in the present invention refers to the number average diameter D expressed by D=ΣDi / N (Di: equivalent circle diameter of particle, N: number of particles).

[0041] The inorganic or organic particles used are not particularly limited. For example, inorganic particles such as wet and dry silica, colloidal silica, aluminum silicate, calcium carbonate, calcium phosphate, and aluminum oxide can be used. Organic particles such as styrene, silicone, acrylic acids, methacrylic acids, polyesters, and divinyl compounds can be used. Among these, inorganic particles such as wet and dry silica, colloidal silica, and aluminum silicate, and particles such as styrene, silicone, acrylic acid, methacrylic acid, polyester, and divinylbenzene are preferred. From an economical standpoint, wet and dry silica, colloidal silica, and aluminum silicate are particularly preferred. These particles may be used in combination of two or more types.

[0042] In the present invention, the inorganic and organic particles used do not include colorants intended for coloring, such as dyes, inorganic pigments, and organic pigments. Specifically, the inorganic and organic particles used in the present invention do not include blue pigments such as red iron oxide, molybdenum red, cadmium red, red chrome yellow, chrome permilion, ultramarine, Prussian blue, cobalt blue, and cerulean blue; inorganic pigments such as chromium oxide, pyridian, emerald green, cobalt green, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, manganese violet, mineral violet, titanium dioxide, barium sulfate, zinc white, zinc sulfate, carbon black, and black iron oxide; and organic pigments such as condensed azo, phthalocyanine, quinacridone, dioxazine, isoindolinone, quinophthalone, and anthraquinone.

[0043] In the laminated polyester film of the present invention, from the viewpoint of antistatic properties, the surface resistivity R1 of the resin layer (X) is 1.0×10 8 Ω / □ or more, 1.0×10 11 It is preferable that the surface resistivity R1 of the resin layer (X) is less than 1.0×10 8 By setting the resistance to Ω / □ or more, handling and processing suitability are favorable. 11 By making the surface resistivity R1 of the resin layer (X) less than Ω / □, the antistatic property is sufficient, and the resin layer (X) can be suitably used as a cover tape for electronic components. 8 Ω / □ or more 8.0×10 10 It is preferable that the resistance is Ω / □ or less, and 1.0×10 8 Ω / □ or more 5.0×10 10It is more preferable that the surface resistivity R1 of the resin layer (X) after the abrasion test is Ω / □ or less. Furthermore, the ratio (R2 / R1) of the surface resistivity R2 after the abrasion test of the resin layer (X) is preferably 2.0 or less, more preferably 1.6 or less, and even more preferably 1.2 or less. When (R2 / R1) is 2.0 or less, sufficient antistatic properties are obtained. The surface resistivities R1 and R2 can be measured under the following conditions: 23°C, 65% relative humidity, and then an applied voltage of 100 V for 10 seconds. The surface resistivity R can be measured using a known digital ultrahigh resistance / microcurrent meter; detailed measurement methods are described later in the Examples. The surface resistivity R1 of the laminated polyester film of the present invention and the surface resistivity R2 after the abrasion test can be adjusted to the aforementioned ranges by adjusting the blending ratio of the acrylic resin (A) and the methacrylate ester-styrene copolymer compound (B) in the coating composition for forming the resin layer (X) to the aforementioned ranges.

[0044] The haze of the laminated polyester film of the present invention is preferably 10% or less, more preferably 8% or less, and even more preferably 7% or less. By keeping the haze at 10% or less, the contents can be easily confirmed when the film is used as a carrier tape for electronic components, which is preferable. Furthermore, the haze change after an abrasion test is preferably 2% or less, more preferably 1.5% or less. By keeping the haze change at 2% or less, the antistatic properties after an abrasion test and the transparency of the laminated polyester film are improved, making it suitable for use as a carrier tape for electronic components.

[0045] To make the haze of the laminated polyester film of the present invention 10% or less, it is preferable to set the number average particle size and content of inorganic or organic particles contained in the polyester film within the above-mentioned ranges. Also, to make the haze change after the abrasion test 2% or less, it is preferable to set the coating composition and compounding ratio for forming the resin layer (X) within the above-mentioned ranges.

[0046] From the viewpoint of reducing the environmental load, the laminated polyester film of the present invention preferably contains at least one of biomass raw materials and recycled raw materials. Here, biomass refers to organic compounds derived from plants that are photosynthesized from carbon dioxide and water. When biomass is burned, it usually becomes carbon dioxide and water again, so biomass can be used as so-called carbon-neutral renewable energy. Furthermore, biomass raw materials refer to polyesters containing structural units derived from biomass.

[0047] When the ratio of plant-derived carbon atoms to the total carbon atoms is taken as the biomass ratio, for example, in an ethylene terephthalate unit, if only the ethylene glycol component is entirely plant-derived, the biomass ratio is theoretically 20%. To increase the biomass ratio beyond that, the terephthalic acid must also be plant-derived, which would have a greater effect in reducing the environmental load but would increase production costs. The ethylene glycol component and the terephthalic acid component may be a combination of petroleum-derived and plant-derived components.

[0048] The lower limit of the biomass degree of the polyester constituting the film is preferably 5%, more preferably 10%, and even more preferably 13%, from the viewpoint of realizing an environmental load reduction effect. A biomass degree of 5% or more is expected to have an environmental load reduction effect. On the other hand, when only considering the reduction of the environmental load, the higher the upper limit of the biomass degree, the better, with 100% being the upper limit. However, from the viewpoint of achieving both production costs and a reduction of the environmental load, a biomass degree of 20% or less is practically preferable.

[0049] As a known method for analyzing the presence or absence of biomass raw materials, for example, the carbon isotope ( 14 C) is used.

[0050] Recycled raw materials are raw materials that are recovered and reused from polyester that has been converted into a chemical product once or multiple times. Examples of recycled raw materials for the release film of the present invention include uncoated portions at both ends in the width direction that are cut and removed during the production process of the release film of the present invention, recovered products of other polyester films, and polyester products that have been distributed in a form other than a film, such as PET bottles. When producing the release film of the present invention, it is preferable to use recycled raw materials in an amount of 90% by mass or less of 100% by mass of polyester raw materials. By limiting the use of recycled raw materials to 90% by mass or less, the amount of highly crystalline polyester that has once been converted into a chemical product is reduced, thereby reducing the decrease in transparency and coloration of the resulting laminated polyester film.

[0051] Biaxially oriented polyester films with antistatic properties are used in applications such as protective films for electronic components, and a major application of protective films is as cover tapes. Here, we will particularly focus on the issues associated with cover tapes for electronic components. When peeling the cover tape from an electronic component, the peeling charge on the cover tape can cause the electronic component to accidentally fly out and be scattered, or discharge can occur between the charged tape and the electronic component, resulting in electrical breakdown of the electronic component.

[0052] Furthermore, in the process of producing the cover tape, multiple layers such as primers and sealants are formed on the conductive polyester film base material, which can result in a problem of reduced antistatic properties due to wear of the antistatic layer.

[0053] The laminated polyester film of the present invention has high transparency, a low surface resistivity, and long-lasting antistatic properties, and is therefore suitable for use in the manufacturing process of electronic components, battery components, or semiconductor components, and is particularly suitable for use as cover tapes for electronic components.

[0054] [Method of manufacturing laminated polyester film] The method for producing the laminated polyester film of the present invention will be described below with reference to examples, but the materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown below can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0055] The laminated polyester film of the present invention is preferably obtained by applying a coating composition containing an acrylic resin (A), a methacrylic acid ester-styrene copolymer compound (B), and, if necessary, a crosslinking agent and a surfactant, onto a polyester film, and, if the coating composition contains a solvent, drying the solvent to form a resin layer (X) on the polyester film.

[0056] In the present invention, when a solvent is contained in the coating composition, it is preferable to use an aqueous solvent as the solvent (to make a water-based coating agent), because the use of an aqueous solvent not only prevents the solvent from rapidly evaporating during the drying process, allows the formation of a uniform composition layer, and is also excellent in terms of environmental impact.

[0057] Here, the aqueous solvent refers to water or a mixture of water and a water-soluble organic solvent, such as alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, ketones such as acetone and methyl ethyl ketone, and glycols such as ethylene glycol, diethylene glycol, and propylene glycol, in any ratio.

[0058] The coating composition is preferably applied to a polyester film by in-line coating. In-line coating is a method in which coating is performed within the polyester film manufacturing process. Specifically, it refers to a method in which coating is performed at any stage from melt extrusion of a polyester resin to biaxial stretching, heat treatment, and winding up. Typically, coating is performed on either an unstretched (unoriented) polyester film (A film) in a substantially amorphous state obtained by melt extrusion and quenching, a uniaxially stretched (uniaxially oriented) polyester film (B film) that has been subsequently stretched in the longitudinal direction, or a biaxially stretched (biaxially oriented) polyester film (C film) that has been further stretched in the width direction and has not yet been heat treated.

[0059] In the present invention, a preferred method is to apply a coating composition to either the polyester film A or B before the crystal orientation is complete, then stretch the polyester film uniaxially or biaxially, and heat-treat the polyester film at a temperature higher than the boiling point of the solvent to complete the crystal orientation of the polyester film and provide the resin layer (X). This method offers advantages in terms of production cost, since it allows for simultaneous polyester film formation and the application and drying of the coating composition (i.e., formation of the resin layer (X)). However, if stretching is performed after coating, the acrylic resin (A) or methacrylate-styrene copolymer compound (B) may aggregate in the resin layer (X), which may lead to cracks in the coating layer due to the aggregation, leading to a deterioration in antistatic properties. Among these, a preferred method is to apply a coating composition to a polyester film (B film) that has been uniaxially stretched in the longitudinal direction, followed by widthwise stretching and heat treatment. This is because, compared to the method of applying to an unstretched film and then biaxially stretching, the stretching step is reduced by one, making it less likely that defects or cracks will occur in the composition layer due to stretching, and making it possible to form a composition layer that has excellent transparency, smoothness, and antistatic properties.

[0060] In the present invention, the resin layer (X) is preferably formed by an in-line coating method due to the various advantages described above. Here, the coating method for the coating composition on the polyester film can be any known coating method, such as a bar coating method, a reverse coating method, a gravure coating method, a die coating method, or a blade coating method.

[0061] The best method for forming the resin layer (X) in the present invention is to apply a coating composition using an aqueous solvent to a polyester film using an in-line coating method, followed by drying and heat treatment. A more preferred method is to in-line coat the coating composition onto the uniaxially stretched B film. In the method for producing the laminated polyester film of the present invention, drying can be carried out at a temperature range of 80 to 130°C to complete removal of the solvent from the coating composition. Heat treatment can be carried out at a temperature range of 160 to 240°C to complete the crystal orientation of the polyester film and the thermal curing of the coating composition, thereby completing the formation of the resin layer (X).

[0062] By forming the resin layer (X) using the in-line coating method, the coating composition is applied, followed by a stretching treatment, which promotes the alignment of the acrylic resin (A) and the methacrylic acid ester-styrene copolymer compound, resulting in excellent antistatic performance. At the same time, the subsequent high-temperature heat treatment improves the stability of the antistatic performance against abrasion and surface treatment.

[0063] The polyester film used in the present invention may have any structure, including, for example, a single-layer structure consisting of Layer A alone; a Layer A / Layer B laminate structure (i.e., a two-type two-layer laminate structure); a Layer A / Layer B / Layer A laminate structure (i.e., a two-type three-layer laminate structure); and a Layer A / Layer B / Layer C laminate structure (i.e., a three-type three-layer laminate structure). The lamination method for the polyester film is not limited, and examples include lamination methods using coextrusion, lamination by lamination, and combinations thereof. However, from the viewpoints of transparency and manufacturing stability, coextrusion is preferred. When forming a laminate, different resin structures may be used to impart different functions to each layer. For example, in the case of a Layer A / Layer B / Layer A laminate structure (i.e., a two-type three-layer laminate structure), Layer B may be composed of homopolyethylene terephthalate from the viewpoint of transparency, and particles may be added to Layer A to impart abrasion resistance and slipperiness. In the present invention, polyester film refers to a resin film in which polyester accounts for 50% by mass or more of the total resin composition.

[0064] The polyester used in the polyester film of the present invention will be described below. First, polyester is a general term for polymers having an ester bond in the main chain, and preferably contains at least one component selected from ethylene terephthalate, propylene terephthalate, ethylene-2,6-naphthalate, butylene terephthalate, propylene-2,6-naphthalate, ethylene-α,β-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate, etc.

[0065] The polyester film using the above polyester is preferably biaxially oriented. A biaxially oriented polyester film is generally an unstretched polyester sheet or film that has been stretched about 2.5 to 5.0 times in both the longitudinal direction and the width direction perpendicular to the longitudinal direction, and then heat-treated to complete the crystal orientation, and exhibits a biaxially oriented pattern in wide-angle X-ray diffraction. When the polyester film is biaxially oriented, it has sufficient thermal stability, particularly dimensional stability and mechanical strength, and also good flatness.

[0066] In addition, various additives such as antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, fillers, antistatic agents, and nucleating agents may be added to the polyester film to the extent that the effects of the present invention are not impaired and the properties of the film are not deteriorated.

[0067] The thickness of the polyester film is not particularly limited and is appropriately selected depending on the application and type, but is usually preferably 5 to 250 μm, more preferably 6 to 200 μm, and most preferably 7 to 150 μm in terms of mechanical strength, handleability, etc. The polyester film may be a composite film obtained by coextrusion, or may be a film obtained by laminating obtained films by various methods.

[0068] Next, the method for producing a laminated polyester film of the present invention will be described using, as an example, a polyethylene terephthalate (PET) film as the polyester film, but the present invention is not limited to this. First, PET pellets and a particle master are thoroughly vacuum-dried, then fed into an extruder, melt-extruded into a sheet at approximately 280°C, and cooled to solidify, producing an unstretched (unoriented) PET film (film A). This film is stretched 2.5 to 5.0 times in the longitudinal direction using rolls heated to 80 to 120°C to obtain a uniaxially oriented PET film (film B). A coating composition of the present invention, prepared to a predetermined concentration, is applied to one side of film B.

[0069] Before coating, the surface of the PET film to be coated may be subjected to a surface treatment such as corona discharge treatment. Surface treatment such as corona discharge treatment improves the wettability of the coating composition to the PET film, preventing repellency of the coating composition and allowing the formation of a resin layer (X) with a uniform coating thickness. After coating, the edges of the PET film are held with clips and guided to a heat treatment zone (preheating zone) at 80 to 130°C to dry the solvent in the coating composition. After drying, the film is stretched 1.1 to 5.0 times in the width direction. It is then guided to a heat treatment zone (heat setting zone) at 160 to 240°C and heat treated for 1 to 30 seconds to complete the crystal orientation.

[0070] In this heat treatment step (heat setting step), a relaxation treatment of 3 to 15% may be carried out in the width direction or the length direction, if necessary. The laminated polyester film thus obtained is a film excellent in transparency, antistatic property, and durability.

[0071] (Methods for measuring characteristics and evaluating effects) The methods for measuring the properties and evaluating the effects in the present invention are as follows.

[0072] (1) Thickness The film to be measured was embedded in epoxy resin, and the cross section of the film was cut out with a microtome. The cross section was observed at 5000x magnification with a transmission electron microscope (TEM H7100 manufactured by Hitachi, Ltd.) to determine the thickness of the polyester film substrate and the laminated polyester film.

[0073] (2) Number average particle size The polyester was removed from the polyester film using a low-temperature plasma ashing method (Yamato Scientific PR-503 model) to expose the particles. This was observed with a transmission electron microscope (Hitachi TEM H7100), and the particle images (light shading caused by the particles) were linked to an image analyzer (Cambridge Instruments QTM900). The observation points were changed and the following numerical processing was performed on more than 5,000 particles. The number-average diameter D obtained by this was taken as the average particle diameter.

[0074] D=ΣDi / N Here, Di is the equivalent circle diameter of the particle, and N is the number of particles.

[0075] (3) Particle content 1 g of polymer was added to 200 ml of 1N KOH methanol solution and heated to reflux to dissolve the polymer. After dissolution, 200 ml of water was added to the solution, and the liquid was then centrifuged to settle the particles, and the supernatant was removed. The particles were washed with more water and centrifuged twice. The particles thus obtained were dried and their mass was measured to calculate the particle content.

[0076] (4) Surface resistivity Surface resistivity R X The measurement was carried out after leaving the sample at 23°C and a relative humidity of 65% for 24 hours, using a digital ultra-high resistance / micro current meter R8340A (manufactured by Advantest Corporation) under that atmosphere, with an applied voltage of 100V for 10 seconds. The unit is Ω / □. The resin laminate surface of the laminated sample was evaluated, and the average value of a total of 10 measurements was taken as the surface resistivity R of the sample. X It was decided.

[0077] (5) Surface free energy Using a DropMaster DM501Hi manufactured by Kyowa Interface Science Co., Ltd., the contact angle was measured five times for each solution of water, ethylene glycol, formamide, and diiodomethane on the surface of the resin layer (X), and the average value of the contact angle for each liquid was calculated. Using the average contact angle, the value of each component was calculated using the following formula, which is derived from the extended Fowkes equation and Young's equation. (γSd·γLd)1 / 2+(γSp·γLp)1 / 2+(γSh·γLh)1 / 2=γ(1+cosθ) Here, γLd, γLp, and γLh represent the characteristic values ​​of the dispersion force, polar force, and hydrogen bonding force components of the test liquid, respectively (according to Panzer's Method IV (described in the Journal of the Japan Adhesion Association, Vol. 15, No. 3, p. 96, 1979)), θ represents the average contact angle of the test liquid on the test surface, and γSd, γSp, and γSh represent the values ​​of the dispersion force, polar force, and hydrogen bonding force components of the film surface, respectively. The values ​​of the three components of the test surface were determined by solving the simultaneous equations obtained by substituting the characteristic values ​​and θ into the above formula. In the present invention, the sum of the values ​​of the dispersion force, polar force, and hydrogen bonding force components thus determined was used as the value of surface free energy.

[0078] (6) Abrasion resistance The laminated polyester film was left to stand for 12 hours under normal conditions (23°C, humidity 50%), and then a 10 cm x 10 cm test piece was cut out. The surface of the resin layer was rubbed using a Gakushin-type abrasion tester manufactured by Daiei Kagaku Seiki Co., Ltd. The surface was judged based on scratches and the amount of white powder generated on the surface as follows, with A and B being considered pass. The amount of white powder generated was confirmed visually. <Rubbing conditions> Manufacturer: Daiei Scientific Instruments Co., Ltd. Device name: Rubbing Tester (Gakushin type abrasion tester) Load capacity: 2kg Number of rubs: 10 times A: No white powder is produced. B: A small amount of white powder was produced. C: A large amount of white powder was produced.

[0079] (7) Hayes Haze measurements were performed after leaving the sample at normal conditions (23°C, relative humidity 50%) for 40 hours, using a turbidity meter "NDH5000" manufactured by Nippon Denshoku Industries Co., Ltd., in accordance with JIS K 7136 "Method of determining haze for transparent materials" (2000 edition). The measurement was performed by irradiating the sample with light from the side where the resin layer was laminated. Ten square samples with sides of 50 mm were prepared, and each was measured once, for a total of 10 times, and the average value was taken as the haze value H1 (%) of the sample.

[0080] Next, after rubbing treatment under the conditions described in the section (6) Abrasion resistance, the haze value H2 (%) after the abrasion test was measured in the same manner as above. The haze change (%) was calculated using the following formula, where the haze before the abrasion test was H1 and the haze after the abrasion test was H2.

[0081] Haze change (%) = |H2-H1|.

[0082] (8) Peak density Spd and mean curvature of protrusions Spc Measurements were performed using a white light interferometer, VertScan2.0 R5300GL-Lite-AC, manufactured by Ryoka Systems Co., Ltd. The attached analysis software was used to perform surface correction of the captured image using a fourth-order polynomial approximation, followed by interpolation (a process in which height data for pixels where no height data could be obtained is supplemented with height data calculated from surrounding pixels), and the cross-sectional cursor was set at any position on the measurement image to determine the cross-sectional profile and cross-sectional roughness parameters (Spd, Spc). Measurements were performed on a rubbed surface with n=10, and the average values ​​were taken as Spd and Spc. The measurement conditions were as follows:

[0083] Manufacturer: Ryoka Systems Co., Ltd. Device name: VertScan2.0 R5300GL-Lite-AC Measurement conditions: CCD camera SONY HR-57 1 / 2 inch (1.27 cm) Objective lens: 50x Intermediate lens: 0.5x Wavelength filter: 520nm white Measurement mode: Phase Measurement software: VS-Measure Version 5.5.1 Analysis software: VS-Viewer Version 5.5.1 Measurement area: 100μm x 100μm.

[0084] (9) Organic fluorine compounds The content of organic fluorine compounds was measured using the following method. For example, to identify the structure of the organic fluorine compounds, the weight peak of the C—F bond in the molecular structure was confirmed by gas chromatography mass spectrometry (GC-MS). Next, the presence or absence of infrared absorption peaks derived from the bonds between each atom in the chemical structure derived from the organic fluorine compounds was confirmed by Fourier transform infrared spectroscopy (FT-IR). Furthermore, proton nuclear magnetic resonance spectroscopy ( 1 Using H-NMR, the position of the chemical shift derived from the position of the fluorine atoms in the chemical structure derived from the organic fluorine compound and the area of ​​the proton absorption line derived from the number of fluorine atoms were confirmed. These results were combined and comprehensively confirmed. The content of the chemical structure derived from the organic fluorine compound was determined by calculating the molar ratio (mol%) of each constituent component of the laminated polyester from the proton absorption line area of ​​the proton nuclear magnetic resonance spectroscopy, and then multiplying this by the molecular weight of each constituent component to calculate the mass, thereby determining the content of the chemical structure derived from the organic fluorine compound among each constituent component of the laminated polyester film.

[0085] (10) Presence or absence of particles on the surface of the resin layer (X) The resin layer side of the laminated polyester film is observed with a scanning electron microscope (SEM), and the foreign matter image is processed with an image analyzer. The SEM magnification is set to 5000 times. 2 The presence or absence of particles was determined by observing 10 randomly selected locations within the range of 0.02 μm or more in equivalent circle diameter. If no particles based on the above definition were observed in this measurement, it was determined that the sample was substantially free of organic and inorganic particles.

[0086] (11) Confirm the structure of the resin that forms the resin layer X The method for confirming the structure of the resin that forms the resin layer X is pyrolysis gas chromatography mass spectrometry (GCMS). C-MS), Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy ( 1 H- Three types of spectroscopy (NMR) are performed, and a comprehensive judgment can be made from all the results. Using pyrolysis GC-MS and FT-IR, the presence or absence and intensity of peaks resulting from the structure of the resin that forms resin layer X can be compared, and the content can be evaluated. The equipment and measurement conditions used for the measurements are shown below.

[0087] <Pyrolysis GC-MS> Pyrolysis furnace: PY-3030D (manufactured by Frontier Lab) Heating temperature: 600℃ GC-MS (Agilent) conditions Column: "UltraALLOY" (registered trademark)-5 5% diphenyl + 95% dimethylpolysiloxane Column temperature: 40°C (3 minutes) - 320°C (18 minutes) at a rate of 20°C / min Injection temperature: 300℃ <ft-ir> IR: Nicolet iS5 (Thermo Fisher Scientific) Sample preparation method: KBr Measurement mode: Transmitted light Resolution: 8cm-1 Accumulation count: 64 times < 1 H-NMR NMR: ECA-400 (JOEL) Resonance wavelength: 399.78MHz Number of scans: 32 [Example]

[0088] The laminated polyester film of the present invention will be described in detail below based on specific examples, but the present invention is not limited to these examples. The types of materials used in the coating compositions are shown below. The blending ratios of each coating composition are shown in Table 1. The blending ratios of the polyester film are shown in Table 2. The properties of the obtained laminated polyester film are shown in Table 3. Acrylic resin (A-1): An emulsion solution (solid concentration 25% by mass) of acrylic resin (emulsion diameter 50 nm) with a glass transition temperature (Tg) of 46°C, consisting of methyl methacrylate (47 mol%), ethyl acrylate (45 mol%), acrylic acid (2 mol%), N-methylol acrylamide (1 mol%), polyethylene glycol monomethacrylate with 16 ethylene oxide repeating units (3 mol%), and 2-sulfoethyl acrylate (2 mol%). Acrylic resin (A-2): An emulsion solution (solid concentration 25%) of acrylic resin (emulsion diameter 50 nm) with a glass transition temperature (Tg) of 67°C, consisting of methyl methacrylate (66 mol%), ethyl acrylate (30 mol%), acrylic acid (3 mol%), and N-methylol acrylamide (1 mol%). Aqueous solutions of the other components were prepared as follows. Methacrylate ester-styrene copolymer (B-1): A reaction vessel was charged with 700 ml of water, 5 parts by mass of sodium polyoxyethylene lauryl ether phosphate (ELEMINOL (registered trademark) CLS-20, manufactured by Sanyo Chemical Industries, Ltd.) as an emulsifier, 20 parts by mass of styrene, 40 parts by mass of methacrylic acid, and 4 parts by mass of methoxybutyl-β-mercaptopropionate as a chain transfer agent, and the mixture was stirred to prepare an emulsified mixture.

[0089] After replacing the air in the reactor with nitrogen gas, 3 parts by mass of dimethyl 2,2'-azobis(isobutyrate) was added as a polymerization catalyst while stirring the emulsion mixture in the reactor, and the temperature of the emulsion mixture was heated to 90°C to initiate radical polymerization. One hour after the start of radical polymerization, 0.2 parts by mass of dimethyl 2,2'-azobis(isobutyrate) was added to the reactor. After 1 hour and 30 minutes, the temperature of the emulsion mixture was cooled to 30°C, yielding a methacrylate ester-styrene copolymer compound. This was diluted with water to a solids concentration of 15% by mass. Antistatic agent (B-2): An aqueous solution of lithium polystyrene sulfonate (weight average molecular weight of 70,000, solid content concentration of 15% by mass) was used. Antistatic agent (B-3): To an aqueous solution containing 20.8 parts by mass of polystyrene sulfonic acid and 1,887 parts by mass of water, 49 parts by mass of a 1% by mass aqueous solution of iron (III) sulfate, 8.8 parts by mass of 3,4-ethylenedioxythiophene, and 117 parts by mass of a 10.9% by mass aqueous solution of peroxodisulfuric acid were added. This mixture was stirred at 18°C ​​for 23 hours. Next, 154 parts by mass of a cation exchange resin and 232 parts by mass of anion exchange resin were added to this mixture and stirred for 2 hours. After that, the ion exchange resin was filtered off to obtain an aqueous dispersion (solids concentration: 1.3% by mass) of a mixture consisting of poly(3,4-ethylenedioxythiophene) (PEDT) (0.5% by mass) and polystyrene sulfonic acid (0.8% by mass).

[0090] Crosslinker (C): Nisshinbo Chemical Inc., "Carbodilite" (registered trademark) V-02 (solid content concentration 40% by mass, solvent: water) Particle (D): Silica particle water dispersion (particle diameter 0.05 μm, solid content 10% by mass) Surfactant (E): GOO Chemical Co., Ltd. "PLASCOAT" (registered trademark) RY-2 (fluorine-based surfactant, solid content concentration 50% by mass, solvent: water) <Material types used for polyester film> The types of materials used for polyester film are listed below.

[0091] Polyester resin (PET-1): Terephthalic acid was used as the acid component and ethylene glycol as the glycol component. Antimony trioxide (polymerization catalyst) was added to the resulting polyester pellets so that the amount was 300 ppm in terms of antimony atoms, and a polycondensation reaction was carried out to obtain polyethylene terephthalate pellets (PET).

[0092] Polyester resin (PET-2): PET with a biomass content of 20% was used.

[0093] Polyester resin (PET-3): Made from recycled PET.

[0094] Particle (M-1): When producing the above polyethylene terephthalate, an ethylene glycol slurry of agglomerated silica particles with an average particle size of 3.0 μm was added after the transesterification reaction, and then a polycondensation reaction was carried out to produce a particle master with a particle concentration of 2 mass% in the polymer.

[0095] Particle (M-2): When producing the above polyethylene terephthalate, an ethylene glycol slurry of agglomerated silica particles with an average particle size of 1.2 μm was added after the transesterification reaction, and then a polycondensation reaction was carried out to produce a particle master with a particle concentration of 2 mass% in the polymer.

[0096] Particle (M-3): When producing the above polyethylene terephthalate, an ethylene glycol slurry of agglomerated silica particles with an average particle size of 0.05 μm was added after the transesterification reaction, and then a polycondensation reaction was carried out to produce a particle master with a particle concentration of 2 mass% in the polymer.

[0097] Example 1 <Paint composition> As a coating composition 1 for forming the resin layer (X), an aqueous dispersion composed of A-1 / B-1=40 / 60 (mass ratio of solid contents) was prepared.

[0098] <Laminated polyester film> PET-1 and particles M-2 were mixed at an 85 / 15 (parts by mass) ratio and thoroughly dried under vacuum. The mixture was then fed into an extruder, melted at 285°C, extruded into a sheet from a T-shaped nozzle, and cooled and solidified by wrapping it around a mirror-finished casting drum at a surface temperature of 25°C using an electrostatic casting method. This unstretched film was heated to 90°C and stretched 3.4 times in the longitudinal direction to produce a uniaxially stretched film (film B).

[0099] Next, coating composition 1 was applied to the corona discharge-treated surface of the uniaxially stretched film using a bar coat. The uniaxially stretched film coated with the coating composition was held at both widthwise ends with clips and guided into a preheating zone. The ambient temperature was then raised to 75°C, followed by a radiation heater to raise the ambient temperature to 110°C, then to 90°C, where the coating composition was dried to form a resin layer (X). The film was then continuously stretched 3.5 times in the widthwise direction in a heating zone (stretching zone) at 120°C, and subsequently heat-treated for 20 seconds in a heat treatment zone (heat setting zone) at 230°C, yielding a laminated polyester film with complete crystal orientation. The thickness of the resulting laminated polyester film, measured by observing the cross section using a transmission electron microscope (TEM), was 20 μm.

[0100] (Examples 2 to 13, Comparative Examples 1 to 3) A laminated polyester film was obtained in the same manner as in Example 1, except that the coating compositions and polyester films shown in Tables 1 and 2 were used.

[0101] [Table 1]

[0102] [Table 2]

[0103] [Table 3] [Industrial Applicability]

[0104] The present invention relates to a laminated polyester film having excellent antistatic properties, abrasion resistance, and transparency. It can be used for a variety of tapes, including those for optical applications such as magnetic recording materials, electrical insulating materials, insulating tapes, electrical materials, and protective films, as well as for graphics, cards, transfer foils, ribbons, vapor deposition, packaging, capacitors, and cover tapes. The film is particularly suitable for carrier tapes because it overcomes the problems inherent in carrier tapes, such as dust adhesion due to peeling electrification, electrical breakdown of electronic components, and a decrease in antistatic properties and transparency under harsh environments. Furthermore, the film is also suitable for cover tape applications because it overcomes the problems inherent in protective films, such as dust adhesion due to peeling electrification, breakdown of electronic elements in displays due to peeling electrification, and a decrease in antistatic properties under harsher environments.

Claims

1. A laminated polyester film having a resin layer (X) containing an acrylic resin (A) and a methacrylic acid ester-styrene copolymer compound (B) on at least one side of a polyester film.

2. A laminated polyester film having a resin layer (X) on at least one side of a polyester film, wherein the surface of the resin layer (X) has a peak density Spd of 300 or more and 1500 or less, and a mean curvature of protrusions Spc of -500 or more and -100 or less.

3. The surface resistivity R1 of the resin layer (X) is 1.0×10 ８ Ω / □ or more 1.0×10 １１ 3. The laminated polyester film according to claim 1, wherein the surface resistivity R2 after an abrasion test is less than Ω / □ and the ratio (R2 / R1) of the surface resistivity R2 after an abrasion test is 2.0 or less. [Wear test conditions] The surface of the resin layer (X) of the laminated polyester film was pressed against a load of 20 g / cm ２ The sample is rubbed back and forth 10 times with a nonwoven fabric (Haise Gaze NT-4 manufactured by Ozu Sangyo Co., Ltd.).

4. 3. The laminated polyester film according to claim 1, which has a haze of 10% or less.

5. 3. The laminated polyester film according to claim 1, wherein the haze change calculated by the following formula, where H1 is the haze before the abrasion test and H2 is the haze after the abrasion test, is 2% or less. Haze change (%) = |H2 - H1| [Wear test conditions] The surface of the resin layer (X) of the laminated polyester film was pressed against a load of 20 g / cm ２ The sample is rubbed back and forth 10 times with a nonwoven fabric (Haise Gaze NT-4 manufactured by Ozu Sangyo Co., Ltd.).

6. 3. The laminated polyester film according to claim 1, wherein the surface free energy of the resin layer (X) is 40 mN / m or more and 60 mN / m or less.

7. 3. The laminated polyester film according to claim 1, comprising inorganic particles or organic particles having a number average particle diameter of 0.01 μm to 5 μm in an amount of 0.01% by mass to 2.00% by mass based on the total mass of the laminated polyester film.

8. 3. The laminated polyester film according to claim 1, wherein the resin layer (X) contains substantially no inorganic particles or organic particles.

9. 3. The laminated polyester film according to claim 1, wherein the laminated polyester film does not contain an organic fluorine compound in an amount of 50 ppm or more.

10. The laminated polyester film according to claim 1 or 2, which is used in the production process of electronic components, battery components, or semiconductor components.

11. The laminated polyester film according to claim 1 or 2, which contains at least one of a biomass raw material and a recycled raw material.

12. 3. A method for producing a laminated polyester film according to claim 1 or 2, comprising: a melt extrusion step of forming a polyester film containing one or more inorganic particles or organic particles; and a step of applying a coating composition containing an acrylic resin (A) and a methacrylic acid ester-styrene copolymer compound to a surface of the polyester film, followed by stretching and heat treatment in at least one direction to form a resin layer (X).

Images