Laminated polyester film

Abstract

To provide a laminated polyester film which suppresses generation of static electricity and can suppress defects such as breakage of a circuit by static electricity, and has good adhesion to an adhesive layer, even when the adhesive layer that contains no fluorine element and has no antistatic property is provided.SOLUTION: A laminated polyester film has a resin layer which does not substantially contain a fluorine component, on at least one surface of the polyester film, wherein surface resistivity on the resin layer side is 1×107 Ω / sq. or less, and when an adhesive layer, which has no antistatic property, is composed of an acrylic adhesive and has thickness of 10 μm, is provided on the resin layer, surface resistivity on the adhesive layer side is 1×1012 Ω / sq. or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated polyester film. [Background technology]

[0002] Polyester films have excellent properties such as mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, and optical properties, and also have excellent cost performance, so they are used in a variety of applications.

[0003] Applications of polyester films include protective films for components such as displays and touch panels, and process protective films that protect components in semiconductor processing steps, etc. When used as a process protective film, it must be peeled off from the adherend when protection is no longer necessary, so a pressure-sensitive adhesive layer that can be peeled off from the adherend is processed onto the surface of the polyester film.

[0004] Resin materials are generally used for polyester films and adhesive layers, but because resin materials have high electrical insulation properties, static electricity is easily generated when peeling them off from the adherend. The generation of static electricity can cause problems due to the adhesion or entrapment of foreign matter, and in recent years, as semiconductor circuits have become increasingly miniaturized, static electricity can destroy the circuits, causing problems such as reduced yields.

[0005] One method for suppressing static electricity generation is to incorporate an antistatic agent into the adhesive layer. Examples of antistatic agents include surfactant compounds, metal compounds, and conductive polymers, but ionic liquids are preferably used because of their excellent antistatic properties, ability to suppress bleed-out, good appearance of the adhesive layer, and low cost (Patent Document 1).

[0006] Ionic liquids used as antistatic agents may contain organic fluorine compounds (abbreviated as PFAS), such as perfluoroalkyl compounds and polyfluoroalkyl compounds (Patent Document 2).

[0007] Furthermore, when an antistatic agent is added to the adhesive layer, the adhesiveness may be affected, and the composition of the adhesive may be limited (Patent Document 3). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-026766 [Patent Document 2] Japanese Patent Publication No. 2023-001742 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-003988 Summary of the Invention [Problem to be solved by the invention]

[0009] Because the above-mentioned perfluoroalkyl compounds are persistent and some are of concern for their ecotoxicity, restrictions on their manufacture and use have been increasing worldwide in recent years, and it is predicted that their continued use will become difficult. For this reason, it is desirable to be able to suppress static electricity when peeling a protective film from an adherend (process) without using ionic liquids containing PFAS in the adhesive layer. Furthermore, if static electricity can be suppressed when peeling a (process) protective film from an adherend without using an antistatic agent in the adhesive layer, an adhesive layer of a general-purpose composition can be used for the (process) protective film, which would make it easier to adjust the adhesiveness and would also be advantageous in terms of cost.

[0010] Therefore, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a laminated polyester film that does not contain a fluorine component, and that, even when provided with an adhesive layer that does not have antistatic properties, can suppress the generation of static electricity, thereby suppressing problems such as circuit destruction due to static electricity and the adhesion or entrapment of foreign matter, and that has good adhesion to the adhesive layer provided. [Means for solving the problem]

[0011] In view of the above problems, the present inventors have conducted extensive research and have found that the above problems can be solved by using a laminated polyester film having a specific structure, thereby completing the present invention. That is, the present invention provides the following aspects [1] to

[17] .

[0012] [1] A polyester film having a resin layer substantially free of fluorine components on at least one surface thereof, and a surface resistivity of the surface side of the resin layer of 1×10 7 Ω / □ or less, and the surface resistivity when a 10 μm thick adhesive layer made of an acrylic adhesive that does not have antistatic properties is provided on the resin layer is 1×10 12 Laminated polyester film with a modulus of elasticity of Ω / □ or less.

[0013] [2] The laminated polyester film according to claim 1, wherein the peel area of ​​the film having the pressure-sensitive adhesive layer on the resin layer is 70% or less in the adhesion evaluation described below. (Adhesion evaluation) A 10 μm thick acrylic adhesive layer without antistatic properties is formed on the resin layer, and 11 vertical and 11 horizontal cuts are made in the adhesive layer at 1 mm intervals using a cross cutter. 18 mm wide cellophane tape is then attached and peeled off at a peel angle of 180 degrees, measuring the peel area.

[0014] [3] The laminated polyester film according to [1] or [2], wherein the resin layer contains (i) a polymer obtained by doping a compound consisting of thiophene or a thiophene derivative with another anionic compound.

[0015] [4] The laminated polyester film according to any one of [1] to [3], wherein the resin layer contains (ii) one or more compounds or derivatives thereof selected from polyglycerin and / or alkylene oxide adducts of polyglycerin.

[0016] [5] The laminated polyester film according to any one of [1] to [4], wherein the resin layer contains (iii) a binder resin.

[0017] [6] The laminated polyester film according to any one of [1] to [5], wherein the resin layer contains (iv) a crosslinking agent.

[0018] [7] The laminated polyester film according to any one of [4] to [6], wherein the (ii) one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin or derivatives thereof is a polyglycerin represented by the following general formula (3):

[0019] [ka] (n is an integer ranging from 2 to 20.)

[0020] [8] The laminated polyester film according to [6] or [7], wherein the (iv) crosslinking agent contains at least one compound selected from an oxazoline compound, an epoxy compound, a carbodiimide compound, and a melamine compound.

[0021] [9] The laminated polyester film according to any one of [6] to [8], wherein the (iv) crosslinking agent is a carbodiimide compound.

[0022]

[10] The laminated polyester film according to any one of [4] to [9], wherein the resin layer contains 30 to 65 mass % of one or more compounds or derivatives thereof selected from (ii) polyglycerin and / or alkylene oxide adducts of polyglycerin.

[0023]

[11] The laminated polyester film according to any one of [5] to

[10] , wherein the binder resin (iii) is contained in the resin layer in an amount of 20 to 50 mass %.

[0024]

[12] The laminated polyester film according to any one of [6] to

[11] , wherein the resin layer contains 25% by mass or less of the crosslinking agent (iv).

[0025]

[13] A protective film for an image display device, comprising the laminated polyester film according to any one of [1] to

[12] .

[0026]

[14] A protective film for use in semiconductor manufacturing processes, comprising the laminated polyester film according to any one of [1] to

[12] .

[0027]

[15] A pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive that does not have antistatic properties provided on the resin layer of the laminated polyester film according to any one of [1] to

[12] .

[0028]

[16] A method for preventing static electricity in a film, comprising providing an adhesive layer made of an adhesive that does not have antistatic properties on the resin layer of the laminated polyester film according to any one of [1] to

[12] .

[0029]

[17] Use of the laminated polyester film according to any one of [1] to

[12] as a substrate for an adhesive film having an adhesive layer that does not have antistatic properties. [Effects of the Invention]

[0030] According to the present invention, even when a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive that does not have antistatic properties is provided on a resin layer, antistatic properties are exhibited, and good adhesion is exhibited between the resin layer and the pressure-sensitive adhesive layer, so that a laminated polyester film that can be suitably used as a protective film for displays, etc. can be provided, and further, the film does not need to contain a fluorine component. DETAILED DESCRIPTION OF THE INVENTION

[0031] An example of an embodiment of the present invention will be described in detail below. However, the present invention is not limited to the embodiment described below, and can be implemented by modifying it as desired within the scope of the gist of the present invention.

[0032] <<<Laminated polyester film>>> The laminated polyester film of the present invention has a resin layer substantially free of fluorine components on at least one surface thereof, and the surface resistivity of the resin layer side is 1×10 7 Ω / □ or less, and when a 10 μm thick adhesive layer made of an acrylic adhesive that does not have antistatic properties is provided on the resin layer, the surface resistivity of the adhesive layer side is 1×10 12 It is characterized by being Ω / □ or less.

[0033] The laminated polyester film of the present invention may have a two-layer structure in which a resin layer is formed on one side of a polyester film and the surface of the polyester film is left as is on the other side, or may have a three-layer or more structure in which other layers are formed on the other side. The other layers may be functional layers having various functions, such as a hard coat layer, an adhesive layer, a decorative layer, a light-shielding layer, a polarizing layer, or an ultraviolet-shielding layer. In addition, resin layers may be formed on both sides of the polyester film. When resin layers are provided on both sides, as described above, the surface resistivity of one of the resin layers is 1×10 7 Although it is preferably Ω / □ or less, there are no particular limitations on the surface resistivity of the other resin layer or the composition of the resin layer. Furthermore, the resin layer may be formed directly on the polyester film, or another layer may be provided between the polyester film and the resin layer. The haze of the laminated polyester film of the present invention is not particularly limited, but is preferably 8% or less, more preferably 5% or less, even more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1.5% or less. The lower limit is not particularly limited, but may be, for example, 0.01%, or may be 0.1%.

[0034] <<Polyester film>> The polyester film (hereinafter referred to as the base polyester film) serving as the base material constituting the laminated polyester film of the present invention may have a single layer structure or a multilayer structure. In the case of a multilayer structure, it may have a two-layer structure, a three-layer structure, or may have four or more layers without departing from the gist of the present invention, and the number of layers is not particularly limited. The base polyester film may be unstretched, uniaxially stretched, or biaxially stretched, but a biaxially stretched polyester film is preferred from the viewpoints of thinning and dimensional stability.

[0035] The polyester used in the base polyester film may be a homopolyester or a copolymer polyester. In the case of homopolyesters, those obtained by polycondensation of aromatic dicarboxylic acids and aliphatic glycols are preferred. Examples of aromatic dicarboxylic acids include terephthalic acid and naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, and examples of aliphatic glycols include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. A typical example of a polyester is polyethylene terephthalate. On the other hand, examples of the dicarboxylic acid component of the copolymer polyester include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid. Examples of the glycol component include one or more of propylene glycols such as ethylene glycol, diethylene glycol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-isopropyl-1,3-propanediol, and 2,2-di-n-1,3-propanediol, butanediol, 1,4-cyclohexanedimethanol, hexanediol, and neopentyl glycol. The intrinsic viscosity of the polyester is not particularly limited, but is preferably 0.5 to 1 dL / g, more preferably 0.53 to 0.9 dL / g, even more preferably 0.56 to 0.80 dL / g, and even more preferably 0.6 to 0.75 dL / g.

[0036] The polyester polymerization catalyst is not particularly limited, and any conventionally known compound can be used, such as a titanium compound, a germanium compound, an antimony compound, a manganese compound, an aluminum compound, a magnesium compound, and a calcium compound.

[0037] As described below, the laminated polyester film of the present invention is suitable, for example, as a protective film for use in the semiconductor processing step in semiconductor manufacturing. Depending on the processing conditions in the semiconductor manufacturing step, oligomer components may precipitate from the substrate polyester film upon heating, causing contamination of the semiconductor. To suppress the amount of oligomer component precipitation, the film may be produced using a polyester with a low oligomer component content as the raw material. Various known methods can be used to produce polyesters with a low oligomer component content, such as a method of solid-state polymerization after polyester production. Alternatively, the amount of oligomer component precipitation may be suppressed by using a substrate polyester film with a three-layer or more structure, with the outermost layer (surface layer) of the substrate polyester film being a layer made from a polyester raw material with a low oligomer component content. Furthermore, the polyester may be obtained by esterification or transesterification, followed by melt polycondensation under reduced pressure at an elevated reaction temperature.

[0038] The polyester film substrate may contain an ultraviolet absorber to improve the weather resistance of the film and prevent deterioration of the adherend (e.g., an image display device using an organic light-emitting diode (OLED) or quantum dots (QD)). The ultraviolet absorber is a compound that absorbs ultraviolet light and is not particularly limited as long as it can withstand the heat applied during the polyester film manufacturing process.

[0039] The ultraviolet absorber includes organic ultraviolet absorbers and inorganic ultraviolet absorbers, and organic ultraviolet absorbers are preferred from the viewpoint of transparency.The organic ultraviolet absorbers are not particularly limited, but examples thereof include cyclic iminoesters, benzotriazoles, and benzophenones.From the viewpoint of durability, cyclic iminoesters and benzotriazoles are more preferred.In addition, two or more types of ultraviolet absorbers can be used in combination.

[0040] The base polyester film may be designed without incorporating particles in order to improve transparency, or may be designed to incorporate particles primarily for the purposes of imparting lubricity and preventing scratches during each process. When particles are incorporated, the type of particles is not particularly limited as long as they are capable of imparting lubricity. Specific examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenolic resin, epoxy resin, and benzoguanamine resin. Furthermore, precipitated particles obtained by precipitating and finely dispersing a portion of a metal compound such as a catalyst during the polyester production process can also be used.

[0041] When particles are blended, there is no particular limitation on their shape, and any of spherical, blocky, rod-like, flat, etc. may be used. There are also no particular limitations on their hardness, specific gravity, color, etc. Two or more types of these particles may be used in combination as needed.

[0042] When particles are incorporated, the average particle size is usually 5 μm or less, preferably 0.01 to 4 μm, preferably 0.1 to 3.5 μm, and more preferably 0.5 to 3 μm. A particle size of 5 μm or less is preferred because it prevents the film surface from becoming too rough, making it less likely to cause problems when various surface functional layers are formed in subsequent processes. Furthermore, a particle size of 0.01 μm or more is preferred because it provides a sufficient effect. The average particle size can be measured, for example, by observing the polyester film using a TEM and averaging the particle sizes of 10 particles. A specific example of a TEM is the Hitachi H-7650 (accelerating voltage 100 V).

[0043] Furthermore, the particle content in the base polyester film is usually less than 5% by mass, preferably less than 3% by mass. When the particle content is less than 5% by mass, the transparency of the film is easily ensured. The lower limit of the particle content is usually 0.01% by mass, preferably 0.1% by mass. When particles are contained, it is preferable to provide a surface layer and an intermediate layer and contain particles in the surface layer, for example. In this case, it is more preferable to have a multilayer structure having a particle-containing surface layer, an intermediate layer, and another particle-containing surface layer in this order.

[0044] The method for incorporating particles into the base polyester film is not particularly limited, and any conventionally known method can be adopted. For example, in the case of a multi-layer base polyester film, the particles can be incorporated at any stage in the production of the polyester constituting each layer, but it is preferable to incorporate the particles after the completion of the esterification or transesterification reaction.

[0045] In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. may be blended into the base polyester film as needed. These preferably do not contain fluorine components.

[0046] The thickness of the base polyester film is not particularly limited as long as it can be formed into a film, but is usually in the range of 10 to 350 μm, preferably 25 to 250 μm, more preferably 38 to 125 μm, and even more preferably 40 to 100 μm.

[0047] Next, specific examples of manufacturing a base polyester film will be described, but the invention is not limited to these examples. For example, when manufacturing a biaxially stretched polyester film, a preferred method is to extrude dried pellets of the polyester raw material described above from a die using an extruder as a molten sheet, and then cool and solidify the molten sheet on a cooling roll such as a rotating cooling drum to obtain an unstretched sheet. In this case, it is preferable to increase the adhesion between the sheet and the rotating cooling drum to improve the flatness of the sheet, and an electrostatic adhesion method and / or a liquid application adhesion method are preferably used. The unstretched sheet is then biaxially stretched. In this case, the unstretched sheet is first stretched in one direction using a roll or tenter-type stretching machine. The stretching temperature is usually 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the sheet is stretched in a direction perpendicular to the first-stage stretching direction, at a stretching temperature of usually 70 to 170°C, and a stretching ratio of usually 3.0 to 7 times, preferably 3.5 to 6 times. Subsequently, the film is heat-treated under tension or relaxation of 30% or less at a temperature of 180 to 270°C to obtain a biaxially oriented film. The stretching may be performed in one direction in two or more stages. In this case, it is preferable to perform the stretching so that the final stretch ratios in both directions are within the above ranges.

[0048] A simultaneous biaxial stretching method can also be used to produce the base polyester film. In the simultaneous biaxial stretching method, the unstretched sheet is simultaneously stretched and oriented in the machine direction (longitudinal direction) and width direction (transverse direction) under temperature control, usually at 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is usually 4 to 50 times, preferably 7 to 35 times, more preferably 10 to 25 times in terms of area ratio. Subsequently, the film is subjected to a heat treatment under tension or relaxation of 30% or less at a temperature of typically 170 to 250°C to obtain a stretched and oriented film. Regarding the simultaneous biaxial stretching device employing the above-mentioned stretching method, any conventionally known stretching method such as a screw method, a pantograph method, or a linear drive method can be employed.

[0049] <<Resin layer>> The laminated polyester film of the present invention has a resin layer formed from a resin composition on at least one surface of a base polyester film. The resin layer of the laminated polyester film of the present invention is substantially free of fluorine components. "Substantially free of fluorine components" means that fluorine compounds are not intentionally contained, and for example, fluorine components may be unavoidably contained. Specifically, this means that the resin layer contains fluorine components in an amount of 1% by mass or less, preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and particularly preferably 0.1% by mass or less.

[0050] The resin composition used in the resin layer according to the present invention is not limited, and the resin layer may be formed by incorporating, for example, an antistatic agent, polyglycerin or the like, a binder resin, a crosslinking agent, etc. Among these, it is preferable to incorporate any one of an antistatic agent, a binder resin such as polyglycerin, and a crosslinking agent, more preferably an antistatic agent, polyglycerin, and a binder resin, and even more preferably an antistatic agent, polyglycerin or the like, a binder resin, and a crosslinking agent. It can be assumed that the resin layer contains unreacted compounds of the various compounds in the resin composition, reacted compounds, or a mixture thereof.

[0051] ((Antistatic agent)) The resin layer according to the present invention may contain an antistatic agent. This antistatic agent does not contain a fluorine compound. Examples of the antistatic agent include surfactant compounds, metal compounds, conductive polymers, and ionic liquids. Conductive polymers are preferred from the viewpoints of excellent antistatic properties, low humidity dependency of surface resistivity, cost, and the ability to form a composition that does not contain a fluorine component.

[0052] Examples of conductive polymers include (i) polymers obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound. For example, a polymer obtained by polymerizing a compound of the following formula (1) or (2) in the presence of a polyanion can be used. Note that different polymers may also be used in combination.

[0053] [ka]

[0054] In the above formula (1), R 1 and R 2 each independently represents hydrogen or an aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group, or the like having 1 to 20 carbon atoms.

[0055] [ka]

[0056] In the above formula (2), n represents an integer of 1 to 4.

[0057] Examples of polyanions used in polymerizing the polymer include poly(meth)acrylic acid, polymaleic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, etc. As a method for producing such a polymer, for example, a method such as that disclosed in JP-A-7-90060 can be used.

[0058] The laminated polyester film of the present invention is preferably a compound of the above formula (2) in which n is 2 and polystyrene sulfonic acid is used as the polyanion.

[0059] When these polyanions are acidic, they may be partially or completely neutralized. Preferred bases for neutralization include ammonia, organic amines, and alkali metal hydroxides.

[0060] ((Polyglycerin, etc.)) In order to improve film-forming properties and antistatic properties when a pressure-sensitive adhesive layer is provided on the resin layer, the resin layer of the laminated polyester film of the present invention preferably contains (ii) one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin or derivatives thereof. Polyglycerin is a compound represented by the following general formula (3):

[0061] [ka]

[0062] In the above formula (3), n is usually in the range of 2 to 20, preferably 2 to 15, more preferably 2 to 10, and even more preferably 2 to 7. By using a compound in this range, it becomes easier to obtain good coating appearance, antistatic properties, durability of the resin layer, etc.

[0063] The alkylene oxide adduct of polyglycerin has a structure in which alkylene oxide is addition polymerized to the hydroxyl group of polyglycerin represented by the general formula (3).

[0064] Here, the structure of the alkylene oxide added to each hydroxyl group in the polyglycerol skeleton may be different, and it is sufficient that the alkylene oxide is added to at least one hydroxyl group in the molecule, and it is not necessary that the alkylene oxide or its derivative is added to all hydroxyl groups.

[0065] The alkylene oxide added to polyglycerol is preferably ethylene oxide or propylene oxide. Of these, ethylene oxide is preferred. The number of added alkylene oxides is preferably such that the number average molecular weight of the final compound is in the range of 200 to 5,000. If the alkylene chain of the alkylene oxide is too long, the hydrophobicity becomes strong, dispersibility in the coating liquid deteriorates, and the antistatic properties and transparency of the resin layer tend to deteriorate, so the chain length is adjusted taking this into consideration.

[0066] The polyglycerin or the alkylene oxide adduct of polyglycerin may be used alone or in combination of two or more kinds.

[0067] (binder resin) The resin layer may contain (iii) a binder resin to improve the coating appearance and transparency, etc. As the (iii) binder resin, various conventionally known polymers, such as polyester resins, acrylic resins, and urethane resins, may also be used in combination. Furthermore, particles may also be used in combination to improve blocking properties and slip properties, etc., within the scope of the present invention. Among these binder resins, it is preferable to use a urethane resin from the viewpoint of improving the coating appearance and adhesion to the pressure-sensitive adhesive layer, and urethane acrylate resins are particularly preferred.

[0068] The urethane resin contained in the resin layer is a polymer compound having a urethane bond in the molecule, and is usually prepared by reacting a polyol with an isocyanate. Examples of the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

[0069] Polycarbonate polyols are obtained by dealcoholization reaction of polyhydric alcohols and carbonate compounds. Examples of polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, trimethylolpropane, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 3,3-dimethylolheptane. Examples of carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate, and examples of polycarbonate polyols obtained by the reaction of these compounds include poly(1,6-hexylene) carbonate and poly(3-methyl-1,5-pentylene) carbonate.

[0070] Examples of polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides and polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2 2-methyl-2-propyl-1,3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamine, lactonediol, etc.), and those having derivative units of lactone compounds such as polycaprolactone.

[0071] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol.

[0072] Examples of polyisocyanates that constitute the urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate; aliphatic diisocyanates having an aromatic ring such as α,α,α',α'-tetramethylxylylene diisocyanate; aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; and alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), dicyclohexylmethane diisocyanate, and isopropylidenedicyclohexyl diisocyanate. These may be used alone or in combination, and these polyisocyanate compounds may be dimers, trimers such as those with an isocyanuric ring, or polymers of higher order. Furthermore, among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferred than aromatic isocyanates in terms of improving adhesion to active energy ray-curable coating materials and preventing yellowing due to ultraviolet rays.

[0073] A chain extender may be used when synthesizing the urethane resin. The chain extender is not particularly limited as long as it has two or more active groups that react with isocyanate groups, and generally, chain extenders having two hydroxyl groups or two amino groups can be mainly used.

[0074] Examples of chain extenders having two hydroxyl groups include glycols such as aliphatic glycols such as ethylene glycol, propylene glycol, butanediol, and pentanediol; aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene; and ester glycols such as neopentyl glycol and neopentyl glycol hydroxypivalate. Examples of chain extenders having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine; aliphatic diamines such as ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3-propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine; and alicyclic diamines such as 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isopropyltrimoniumcyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane, 1,3-bisaminomethylcyclohexane, and isophoronediamine.

[0075] The urethane resin contained in the resin layer may be one that uses a solvent as a medium, but is preferably one that uses water as a medium. To disperse or dissolve the urethane resin in water, there are a forced emulsification type that uses an emulsifier, a self-emulsification type in which a hydrophilic group is introduced into the urethane resin, and a water-soluble type. In particular, a self-emulsification type in which an ionic group is introduced into the skeleton of the urethane resin to form an ionomer is preferred, as it has excellent storage stability of the liquid and excellent water resistance, transparency, and adhesion of the resulting coating layer. The ionic group to be introduced may be a carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, quaternary ammonium salt, or the like, but a carboxyl group is preferred. Various methods can be used to introduce a carboxyl group into a urethane resin at each stage of the polymerization reaction. For example, a resin containing a carboxyl group may be used as a copolymerization component during prepolymer synthesis, or a component containing a carboxyl group may be used as a component of a polyol, polyisocyanate, chain extender, or the like. A preferred method involves using a carboxyl group-containing diol and introducing the desired amount of carboxyl groups by adjusting the amount of this component charged. For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis-(2-hydroxyethyl)propionic acid, bis-(2-hydroxyethyl)butanoic acid, or the like can be copolymerized with the diol used in the polymerization of the urethane resin. Furthermore, the carboxyl group is preferably neutralized with ammonia, amines, alkali metals, inorganic alkalis, or the like to form a salt. Ammonia, trimethylamine, and triethylamine are particularly preferred. In the drying process of the coating solution, the carboxyl groups of such urethane resins, from which the neutralizing agent is removed, can be used as crosslinking reaction sites for other crosslinking agents, which not only provides excellent stability in the liquid state before coating, but also makes it possible to further improve the durability, water resistance, blocking resistance, etc. of the resulting coating layer.

[0076] From the viewpoint of improving adhesion, the urethane resin of the resin layer is preferably a urethane resin containing a carbon-carbon double bond, more preferably a urethane resin composed of polycarbonate polyols or polyester polyols and containing a carbon-carbon double bond, and particularly preferably a urethane resin composed of polyester polyols and containing a carbon-carbon double bond.

[0077] The carbon-carbon double bond-containing urethane resin is a urethane resin having a carbon-carbon double bond therein, and conventionally known materials can be used. For example, the carbon-carbon double bond may be introduced into the urethane resin in the form of an acrylate group, a methacrylate group, a vinyl group, an allyl group, or the like.

[0078] Various substituents can be introduced into the carbon-carbon double bond, and may include, for example, alkyl groups such as methyl and ethyl groups, phenyl groups, halogen groups, ester groups, amide groups, or structures such as conjugated double bonds. The number of substituents is not particularly limited, and mono-, di-, tri-, or tetra-substituted compounds can be used, with mono- or di-substituted compounds being preferred in terms of reactivity, and mono-substituted compounds being even more preferred.

[0079] From the viewpoint of ease of introduction into the urethane resin and adhesion to the pressure-sensitive adhesive layer, an acrylate group or a methacrylate group is preferred, an acrylate group or a methacrylate group without a substituent is more preferred, and an acrylate group without a substituent is particularly preferred.

[0080] ((Crosslinking agent)) The resin layer may contain (iv) a crosslinking agent for the purpose of improving durability, particularly the durability of antistatic performance. Various known crosslinking agents can be used as the crosslinking agent, including, for example, carbodiimide compounds, oxazoline compounds, epoxy compounds, isocyanate compounds, melamine compounds, and silane coupling compounds. Among these, in order to achieve good antistatic properties and improve adhesion to the adhesive layer, it is preferable to contain one or more compounds selected from carbodiimide compounds, oxazoline compounds, epoxy compounds, and melamine compounds, and particularly it is preferable to contain a carbodiimide compound.

[0081] (Carbodiimide compounds) A carbodiimide compound is a compound having a carbodiimide structure, and is a compound having one or more carbodiimide structures in the molecule. For better adhesion, etc., a polycarbodiimide compound having two or more carbodiimide structures in the molecule is more preferred.

[0082] Carbodiimide compounds can be synthesized by conventionally known techniques, and generally involve the condensation reaction of a diisocyanate compound. The diisocyanate compound is not particularly limited, and either an aromatic or aliphatic diisocyanate can be used. Specific examples include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate.

[0083] The content of carbodiimide groups contained in the carbodiimide compound, in terms of carbodiimide equivalent (weight [g] of the carbodiimide compound required to provide 1 mol of carbodiimide groups), is usually in the range of 100 to 1000, preferably 250 to 800, and more preferably 300 to 700. Use in the above range improves the durability of the coating film.

[0084] Furthermore, within the scope of the present invention, in order to improve the water solubility or water dispersibility of the polycarbodiimide compound, a surfactant may be added, or a hydrophilic monomer such as a polyalkylene oxide, a quaternary ammonium salt of a dialkylamino alcohol, or a hydroxyalkyl sulfonate may be added.

[0085] (Oxazoline compounds) An oxazoline compound is a compound having an oxazoline group in the molecule. A polymer containing an oxazoline group is particularly preferred. The compound can be prepared by polymerizing an addition-polymerizable oxazoline group-containing monomer alone or with other monomers. Examples of the addition-polymerizable oxazoline group-containing monomer include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These monomers can be used alone or in combination. Among these, 2-isopropenyl-2-oxazoline is preferred because it is readily available industrially. The other monomer is not limited as long as it is copolymerizable with the addition-polymerizable oxazoline group-containing monomer, and examples thereof include (meth)acrylic acid esters such as alkyl(meth)acrylate (the alkyl group can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid, and salts thereof (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth)acrylamide, N-alkyl(meth)acrylate, N-methyl-N ... Examples of suitable monomers include unsaturated amides such as t)acrylamide and N,N-dialkyl(meth)acrylamide (the alkyl group can 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 cyclohexyl group, and the like); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogen-containing α,β-unsaturated monomers such as vinyl chloride and vinylidene chloride; and α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and one or more of these monomers can be used. From the viewpoint of improving adhesion, the amount of oxazoline groups in the oxazoline compound is preferably in the range of 0.5 to 10 mmol / g, more preferably 1 to 9 mmol / g, still more preferably 3 to 8 mmol / g, and particularly preferably 4 to 6 mmol / g.

[0086] (epoxy compounds) Epoxy compounds are compounds having an epoxy group in the molecule, and examples thereof include condensation products of epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin, bisphenol A, etc. with a hydroxyl group or an amino group, polyepoxy compounds, diepoxy compounds, monoepoxy compounds, and glycidylamine compounds. Examples of polyepoxy compounds include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl)isocyanate, glycerol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. Examples of diepoxy compounds include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, ethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether. Examples of monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether. Examples of glycidylamine compounds include N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N-diglycidylamino)cyclohexane. From the viewpoint of improving adhesion, polyether-based epoxy compounds are preferred. As for the number of epoxy groups, bifunctional polyepoxy compounds are preferred, and trifunctional or higher polyepoxy compounds are more preferred.

[0087] (melamine compounds) The melamine compound refers to a compound having a melamine skeleton within the compound. Examples of such compounds include alkylolated melamine derivatives, compounds obtained by reacting alkylolated melamine derivatives with alcohols to partially or completely etherify them, and mixtures thereof. Suitable alcohols for etherification include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, and isobutanol. The melamine compound may be a monomer or a dimer or higher polymer, or a mixture thereof. Furthermore, melamine may be partially co-condensed with urea or the like, and a catalyst may be used to increase the reactivity of the melamine compound.

[0088] (Isocyanate compounds) The isocyanate compound refers to a compound having an isocyanate or an isocyanate derivative structure, such as a blocked isocyanate. Examples of the isocyanate include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate, aliphatic isocyanates having an aromatic ring such as α,α,α',α'-tetramethylxylylene diisocyanate, aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate, and alicyclic isocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), and isopropylidenedicyclohexyl diisocyanate. Further examples include polymers and derivatives of these isocyanates, such as biuretized products, isocyanurated products, urethodionated products, and carbodiimide-modified products. These may be used alone or in combination. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferred than aromatic isocyanates in order to prevent yellowing due to ultraviolet rays.

[0089] When used in the form of a blocked isocyanate, examples of the blocking agent include bisulfites, phenolic compounds such as phenol, cresol, and ethylphenol, alcohol compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol, active methylene compounds such as methyl isobutanoylacetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, and acetylacetone, mercaptan compounds such as butyl mercaptan and dodecyl mercaptan, lactam compounds such as ε-caprolactam and δ-valerolactam, amine compounds such as diphenylaniline, aniline, and ethyleneimine, acetanilide, acid amide compounds of acetic acid amide, and oxime compounds such as formaldehyde, acetaldoxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime, and these may be used alone or in combination of two or more.

[0090] The isocyanate compound may be used alone or as a mixture or bond with various polymers. In order to improve the dispersibility and crosslinkability of the isocyanate compound, it is preferable to use a mixture or bond with a polyester resin or a urethane resin.

[0091] <Composition ratio of resin layer> The content of the antistatic agent in the resin layer is preferably 2 to 30 mass %, more preferably 3 to 20 mass %, even more preferably 5 to 15 mass %, and even more preferably 8 to 12 mass %, as a proportion of all nonvolatile components in the resin composition forming the resin layer. When the content is equal to or less than the upper limit, the strength and transparency of the resin layer tend to be maintained at a good level. On the other hand, when the content is equal to or more than the lower limit, the antistatic performance tends to be good.

[0092] The content of one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin or derivatives thereof in the resin layer is preferably 30 to 70% by mass, more preferably 33 to 60% by mass, even more preferably 35 to 55% by mass, even more preferably 38 to 52% by mass, even more preferably 40 to 50% by mass, or 42 to 48% by mass, based on the total non-volatile components in the resin composition forming the resin layer. If the content is below the upper limit, the proportion of other components increases, which tends to improve the antistatic properties and film-forming properties of the resin layer. On the other hand, if the content is above the lower limit, the transparency of the resin layer tends to be good.

[0093] The content of the binder resin in the resin layer, as a proportion of all nonvolatile components in the resin composition forming the resin layer, is preferably 20 to 55% by mass, more preferably 25 to 50% by mass, even more preferably 30 to 45% by mass, and even more preferably 35 to 43% by mass. When the content is equal to or less than the upper limit, the antistatic properties and transparency of the resin layer tend to be good. On the other hand, when the content of the binder resin is equal to or more than the lower limit, the adhesion to the pressure-sensitive adhesive layer tends to be good.

[0094] The content of the crosslinking agent in the resin layer, as a proportion of all nonvolatile components in the resin composition forming the resin layer, is typically 40% by mass or less, preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, even more preferably 23% by mass or less, and more preferably 15% by mass or less. When the content is below the upper limit, the antistatic properties and transparency of the resin layer tend to be good. On the other hand, the lower limit is not particularly limited, but is preferably above 0% by mass, more preferably 3% by mass or more, even more preferably 5% by mass or more, even more preferably 7% by mass or more, and even more preferably 9% by mass or more. When the content of the crosslinking agent is above the lower limit, adhesion to the pressure-sensitive adhesive layer is improved, and solvent resistance is improved, which tends to result in good resistance when the pressure-sensitive adhesive is coated.

[0095] As a proportion of all non-volatile components in the resin composition that forms the resin layer, the ratio of the content of the antistatic agent in the resin layer to the content of one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin in the resin layer (antistatic agent content / content of one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin) is preferably 2.6 to 7, more preferably 3 to 6.6, even more preferably 3.2 to 6, still more preferably 3.8 to 5.6, even more preferably 4 to 5.2, and still more preferably 4.2 to 4.8.

[0096] As a proportion of all non-volatile components in the resin composition that forms the resin layer, the ratio of the content of the antistatic agent in the resin layer to the content of the binder resin in the resin layer (antistatic agent content / binder resin content) is preferably 2 to 6, more preferably 2.3 to 5.5, even more preferably 2.7 to 5.2, even more preferably 3 to 5, even more preferably 3.3 to 4.6, and even more preferably 3.5 to 4.3.

[0097] As a proportion of all non-volatile components in the resin composition that forms the resin layer, the ratio of the content of the antistatic agent in the resin layer to the content of the crosslinking agent in the resin layer (antistatic agent content / crosslinking agent content) is preferably 0.5 to 4, more preferably 0.8 to 3.5, even more preferably 1 to 3, even more preferably 1.2 to 2.7, even more preferably 1.6 to 2.3, and even more preferably 1.8 to 2.1.

[0098] As a proportion of all non-volatile components in the resin composition that forms the resin layer, the ratio of the content of the binder resin in the resin layer to the content of one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin in the resin layer (content of binder resin / content of one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin) is preferably 0.1 to 2.5, more preferably 0.3 to 2.2, even more preferably 0.5 to 2, even more preferably 0.7 to 1.7, even more preferably 0.9 to 1.5, and even more preferably 1 to 1.3.

[0099] The various components in the resin layer can be analyzed by, for example, TOF-SIMS, ESCA, fluorescent X-ray analysis, or the like.

[0100] <Thickness of resin layer> The thickness of the resin layer is preferably 0.002 μm to 1 μm, more preferably 0.005 μm to 0.5 μm, even more preferably 0.01 μm to 0.25 μm, even more preferably 0.02 μm to 0.15 μm, and even more preferably 0.03 μm to 0.1 μm. A thinner resin layer improves transparency and coating appearance, but tends to degrade antistatic properties. A thicker resin layer reduces resistance and improves antistatic properties, but at a certain thickness, resistance saturates, tending to degrade transparency and coating appearance, as well as increasing paint costs for antistatic properties. Therefore, if the resin layer thickness is within the above range, transparency, coating appearance, antistatic properties, paint costs, and the like are likely to be improved.

[0101] <Method for forming resin layer> Next, a method for forming the resin layer constituting the laminated polyester film of the present invention will be described. The method for forming the resin layer is not particularly limited, and any conventionally known coating method can be used, such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, etc. The resin layer can be formed by in-line coating or off-line coating. The drying and curing conditions are not particularly limited. For example, when the resin layer is formed by off-line coating, the heat treatment is typically carried out at 80 to 200°C for 3 to 40 seconds, preferably at 100 to 180°C for 3 to 40 seconds. On the other hand, when the resin layer is formed by in-line coating, the heat treatment is typically carried out at 70 to 280°C for 3 to 200 seconds.

[0102] In the present invention, it is preferable to form the protective layer by in-line coating, in which the surface of the base polyester film is treated during the film-forming process. Inline coating is a method of coating within the manufacturing process of a polyester base film. Specifically, it is a method of coating at any stage between melt extrusion of polyester, stretching, heat setting, and winding up. Typically, coating is performed on an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, or a film after heat setting and before winding up. While not limited to the following, for example, in sequential biaxial stretching, a method in which coating is performed on a uniaxially stretched film stretched in the longitudinal direction (machine direction) and then stretched in the transverse direction is particularly advantageous. This method offers advantages in terms of production cost, since film formation and resin layer formation can be performed simultaneously. Furthermore, since stretching is performed after coating, the thickness of the resin layer can be changed by adjusting the stretch ratio, making thin-film coating easier than offline-coated films. Furthermore, by providing a resin layer on the film before stretching, the resin layer can be stretched together with the polyester base film, thereby firmly adhering the resin layer to the polyester base film. Furthermore, in the production of biaxially stretched polyester films, by stretching the film while holding its edges with clips or the like, the film can be constrained in both the longitudinal and transverse directions, and in the heat setting step, high temperatures can be applied while maintaining flatness and without wrinkles, etc. Therefore, the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, improving the film-forming properties of the resin layer and enabling stronger adhesion between the resin layer and the base polyester film, and further enabling the formation of a strong resin layer, which can improve performance such as adhesion to various functional layers that can be formed on the resin layer and moist heat resistance.

[0103] When the resin layer is formed by inline coating, it is preferable to produce a laminated polyester film by coating the resin composition prepared as an aqueous solution or aqueous dispersion onto a base polyester film, with the solid content (total non-volatile components) adjusted to approximately 0.1 to 50 mass %.

[0104] In addition, regardless of whether off-line coating or in-line coating is used, heat treatment and irradiation with active energy rays such as ultraviolet radiation may be used in combination as necessary. The base polyester film constituting the laminated polyester film of the present invention may be previously subjected to a surface treatment such as a corona treatment or a plasma treatment.

[0105] (Surface resistivity of the resin layer side) The antistatic property of the resin layer of the laminated polyester film of the present invention can be evaluated by measuring the surface resistivity of the resin layer surface. The lower the surface resistivity of the resin layer side, the better the antistatic property. The surface resistivity of the resin layer surface is 1×10 7 Ω / □ or less is preferable, and 5×10 6 Ω / □ or less, more preferably 1×10 6 Ω / □ or less, and even more preferably 5×10 5 Ω / □ or less, and even more preferably 1×10 5 Ω / □ or less. This range can be said to provide good antistatic properties. There is no particular lower limit for the surface resistivity, but considering the cost of the conductive agent, it is recommended to use a surface resistivity of 1×10 3 It is preferable to set it to Ω / □ or more, and 5×10 3 It may be Ω / □ or more. The surface resistivity of the resin layer side can be measured as shown in the following examples.

[0106] (Surface resistivity of adhesive layer side when adhesive layer is provided) In order to suppress static electricity when peeled from an adherend, the laminated polyester film of the present invention has a surface resistivity of 1×10 when a 10 μm thick adhesive layer made of an acrylic adhesive that does not have antistatic properties is provided on the resin layer. 12 It is preferably Ω / □ or less, and more preferably 6×10 11 Ω / □ or less, more preferably 3×10 11 Ω / □ or less, and even more preferably 1×10 11 Ω / □ or less. If the resistance is in this range, it can be said that the antistatic property is good. The acrylic adhesive used in this case may be, for example, an adhesive having a composition of an acrylic adhesive as the base agent, a polyisocyanate-based crosslinking agent, and an alkylphenone-based curing agent, with the blending ratio of base agent / crosslinking agent / curing agent being 100 / 0.5-2 / 1-2. More specifically, the adhesives shown in the following examples may be used. In the present invention, "not having antistatic properties" means not only the case where an antistatic agent is not contained, but also the case where the content of the antistatic agent is so small that antistatic performance cannot be exhibited. Specifically, "not having antistatic properties" means, for example, a case where the surface resistivity is 1×10 14 This means that it is Ω / □ or more. The surface resistivity of the pressure-sensitive adhesive layer side can be measured as shown in the following examples.

[0107] <<Application>> The laminated polyester film of the present invention can be used, for example, as a substrate for providing a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive that does not have antistatic properties on a resin layer.The laminated polyester film of the present invention can be provided with a pressure-sensitive adhesive layer and attached to an adherend, and can be used to protect the surface of an adherend such as an image display device or to fix a semiconductor in a semiconductor manufacturing process. More specifically, it can be used as a protective film for image display devices to prevent scratches during the manufacturing or transportation process of touch panels, LEDs, and OLEDs (organic light-emitting diodes), and is particularly suitable as a protective film for OLEDs to protect OLEDs. It can also be used as a protective film for use in semiconductor manufacturing processes, such as a dicing tape used to fix a substrate during semiconductor processing, or a backgrind tape applied to a substrate to protect the surface of the substrate during semiconductor manufacturing processes.

[0108] ((Adhesive layer)) The laminated polyester film of the present invention can be made into a pressure-sensitive adhesive film, for example, by providing a pressure-sensitive adhesive layer on the resin layer of the laminated polyester film of the present invention as a substrate. In this case, there are no limitations on the pressure-sensitive adhesive layer provided on the resin layer, but it is preferably formed from a pressure-sensitive adhesive that does not contain a fluorine component and can be peeled off after being applied to an adherend. A general-purpose pressure-sensitive adhesive that does not contain an antistatic agent can be used. For example, an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, etc., as described below, can be used. In this way, even if a pressure-sensitive adhesive layer is formed on the resin layer of the laminated polyester film of the present invention using a pressure-sensitive adhesive that does not have antistatic properties, the pressure-sensitive adhesive film can still have antistatic properties. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably in the range of 5 to 50 μm, more preferably 10 to 40 μm, in order to develop adhesive strength with the adherend. The adhesion between the resin layer and the pressure-sensitive adhesive layer is evaluated such that the peeled area is preferably 70% or less, more preferably 50% or less, even more preferably 20% or less, and most preferably 5% or less. The adhesiveness between the resin layer and the pressure-sensitive adhesive layer can be evaluated by measuring the adhesiveness as shown in the following examples.

[0109] (acrylic adhesive) The acrylic adhesive can be formed from a conventionally known adhesive composition, containing a (meth)acrylic acid ester (co)polymer and, if necessary, a photopolymerization initiator, a crosslinking agent, a silane coupling agent, and other materials. For example, the adhesive composition described in JP 2019-210446 A can be used.

[0110] (urethane adhesive) The urethane-based adhesive can be formed from an adhesive composition containing, as the urethane-based base polymer, a reaction product of a polyol and a polyisocyanate compound, or the like. Examples of the polyol component include polymer-type polyols such as polyester polyols, polyether polyols, polycarbonate polyols, caprolactone polyols, etc. These polyol components may be used alone or in combination of two or more. Examples of polyisocyanate compounds include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. These polyisocyanate compounds may be used alone or in combination of two or more.

[0111] (Silicone adhesive) The silicone-based pressure-sensitive adhesive can be formed from a pressure-sensitive adhesive composition containing silicone as a main resin component. The term "main component resin" refers to the resin that has the largest content (mass) among the resins that make up the adhesive. Examples of adhesive compositions containing silicone as a main resin include addition reaction type, peroxide curing type, and condensation reaction type silicone adhesives. Among these, addition reaction type silicone adhesives are preferably used because they can be cured at low temperatures in a short time. These addition reaction type silicone adhesives form an adhesive layer on the support by curing. When an addition reaction type silicone adhesive is used as the silicone adhesive, the silicone adhesive may contain a catalyst such as a platinum catalyst.

[0112] For example, an addition reaction type silicone pressure-sensitive adhesive can be prepared by adding a catalyst such as a platinum catalyst to a silicone resin solution diluted with a solvent such as toluene, stirring the solution to homogeneity, and then coating the solution on a substrate and curing the solution at 100 to 130° C. for 1 to 5 minutes. If necessary, a crosslinking agent or an additive for controlling adhesive strength may be added to the addition reaction type silicone pressure-sensitive adhesive, or the substrate film may be subjected to a primer treatment before forming the adhesive layer.

[0113] Commercially available silicone resins used in addition reaction type silicone pressure sensitive adhesives include, for example, SD4580PSA, SD4584PSA, SD4585PSA, SD4587LPSA, SD4560PSA, SD4570PSA, SD4600FCPSA, SD4593PSA, DC7651ADHESIVE, DC7652ADHESIVE, LTC-755, LTC-310 (all manufactured by Dow Corning Toray Co., Ltd.), KR-3700, KR-3701, KR-3704, X-40-3237-1, X-40-3240, Examples of suitable anti-inflammatory agents include X-40-3291-1, X-40-3229, X-40-3323, X-40-3306, and X-40-3270-1 (all manufactured by Shin-Etsu Chemical Co., Ltd.), AS-PSA001, AS-PSA002, AS-PSA003, AS-PSA004, AS-PSA005, AS-PSA012, AS-PSA014, and PSA-7465 (all manufactured by Arakawa Chemical Industries, Ltd.), and TSR1512, TSR1516, and TSR1521 (all manufactured by Momentive Performance Materials, Inc.).

[0114] <<<Term Explanation>>> In the present invention, the term "film" includes the term "sheet," and the term "sheet" includes the term "film." In the present invention, when "X to Y" (X and Y are any numbers) is stated, unless otherwise specified, it means "X or more and Y or less," and also includes the meanings "preferably greater than X" or "preferably smaller than Y." Furthermore, when "X or more" (X is any number), it includes the meaning "preferably greater than X" unless otherwise specified, and when "Y or less" (Y is any number), it also includes the meaning "preferably smaller than Y" unless otherwise specified. [Example]

[0115] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples within the scope of the present invention. The measurement and evaluation methods used in the present invention are as follows.

[0116] (1) Intrinsic viscosity of polyester 1 g of polyester from which components incompatible with the polyester had been removed was precisely weighed, dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50 / 50 (mass ratio), and measured at 30°C.

[0117] (2) Resin layer thickness The surface of the resin layer was stained with RuO4 and embedded in epoxy resin. Then, ultrathin sections were prepared and stained with RuO4, and the cross-sections of the resin layer were analyzed using a transmission electron microscope (TEM) (Hitachi High-Technologies Corporation, H-7650, accelerating voltage 100 kV).

[0118] (3) Haze measurement method Measurements were made in accordance with JIS K 7136:2000 using a haze meter "HM-150" manufactured by Murakami Color Research Laboratory.

[0119] (4) Method for measuring the surface resistivity of the resin layer side Using a low resistivity meter, Loresta GP MCP-T600, manufactured by Mitsubishi Chemical Analytech Co., Ltd., the surface resistivity was measured after 30 minutes of conditioning the sample in a measurement atmosphere of 23°C and 50% RH. If the surface resistivity was higher than the upper limit of the measurable range, it was deemed unmeasurable.

[0120] (5) Method for measuring the surface resistivity of the adhesive layer The adhesive below was mixed in a ratio of base agent / crosslinking agent / curing agent = 100 / 1 / 1.4, diluted with ethyl acetate, and coated onto a release coated film MRF38 manufactured by Mitsubishi Chemical Corporation. Main ingredient: Mitsubishi Chemical Corp. Coponyl N-4790 (acrylic) Crosslinking agent: Mitsui Chemicals Takenate D-101E (polyisocyanate) Hardener: IGM Resins Omnirad 184 (alkylphenone type) The adhesive was applied and dried at 100°C for 3 minutes to obtain a film with an adhesive layer having a dry thickness of 10 μm on the release coat. The laminated polyester film of the present invention was laminated with a 2 kg roller so that the adhesive layer and the resin layer of the laminated polyester film were in contact with each other, and then aged at 40°C for 3 days. Next, using an ultraviolet irradiation device, a high-pressure mercury lamp of 160 W was used with an integrated light intensity of 500 mJ / cm 2 The release coated film was then peeled off from the adhesive layer to obtain a film for evaluation in which the adhesive layer was provided on the resin layer. For the pressure-sensitive adhesive layer of the evaluation film, a high resistivity meter, Hiresta UX MCP-HT800, manufactured by Nitto Seiko Analytech Co., Ltd., was used to measure the surface resistivity after 1 minute at an applied voltage of 500 V after 30 minutes of humidity conditioning of the sample in a measurement atmosphere of 23°C and 50% RH. If the surface resistivity was higher than the upper limit of the measurable range, it was deemed unmeasurable.

[0121] (6) Method for evaluating the adhesion between the resin layer and the adhesive layer A cross cutter was used to make 11 vertical and 11 horizontal cuts at 1 mm intervals in the adhesive layer of the evaluation film (5) above, and an 18 mm wide tape (Cellotape LP-18 manufactured by Nichiban Co., Ltd.) was attached and rapidly peeled off at a peeling angle of 180 degrees. After that, the peeled surface was observed and rated as ○ if the peeled area was 5% or less, ○△ if it was more than 5% but not more than 20%, △ if it was more than 20% but not more than 50%, △ if it was more than 50% but not more than 70%, and × if it was more than 70%.

[0122] The polyester raw materials used in the examples and comparative examples are as follows:

[0123] <Method for producing polyester (1)> Starting materials were 100 parts by mass of dimethyl terephthalate and 55 parts by mass of ethylene glycol. 0.04 parts by mass of magnesium acetate tetrahydrate was added to the reactor as a catalyst. The reaction was initiated at 150°C. As methanol was distilled off, the reaction temperature was gradually increased to 230°C after 3 hours. After 4 hours, the transesterification reaction was essentially complete. 0.02 parts by mass of ethyl acid phosphate was added to the reaction mixture, followed by 0.04 parts by mass of antimony trioxide. The polycondensation reaction was carried out for 4 hours. The temperature was gradually increased from 230°C to 280°C. Meanwhile, the pressure was gradually reduced from atmospheric pressure to a final value of 0.3 mmHg. After the start of the reaction, the reaction was terminated at a point corresponding to an intrinsic viscosity of 0.65 dL / g due to changes in the stirring power of the reactor. The polymer was discharged under nitrogen pressure, yielding polyester (1) with an intrinsic viscosity of 0.65 dL / g.

[0124] <Method for producing polyester (2)> The starting materials were 100 parts by mass of dimethyl terephthalate and 45 parts by mass of ethylene glycol. 0.06 parts by mass of magnesium acetate tetrahydrate was added to the reactor as a catalyst. The reaction was initiated at 150°C and gradually increased to 230°C after 3 hours as methanol was distilled off. After 4 hours, the transesterification reaction was essentially complete. 0.03 parts by mass of ethyl acid phosphate was added to the reaction mixture, followed by 0.3 parts by mass of silica particles with an average particle size of 2.7 μm dispersed in ethylene glycol and 0.03 parts by mass of antimony trioxide. The polycondensation reaction was carried out for 4 hours. The temperature was gradually increased from 230°C to 280°C. Meanwhile, the pressure was gradually reduced from atmospheric pressure to a final value of 0.3 mmHg. Due to changes in the stirring power of the reactor, the reaction was terminated at a point corresponding to an intrinsic viscosity of 0.65 dL / g. The polymer was discharged under nitrogen pressure, yielding polyester (2) with an intrinsic viscosity of 0.65 dL / g.

[0125] The following resin composition was used to form the resin layer.

[0126] antistatic agent (A1): A conductive agent (Orgacon ICP1010 manufactured by Agfa-Gevaert) consisting of polyethylenedioxythiophene and polystyrene sulfonic acid, neutralized with concentrated aqueous ammonia to a pH of 9.

[0127] Polyglycerin and / or alkylene oxide adducts of polyglycerin (B1): Polyglycerol in which the average n is 2 in the formula (3). (B2): Polyglycerol in which the average n is 7 in the formula (3). (B3): Polyglycerol in which the average n is 10 in the formula (3). (B4): A compound in which an average of four molecules of ethylene oxide are added to diglycerin. (B5): Glycerin monomer

[0128] Crosslinking agent (C1): Carbodiimide compound Carbodilite SV-02 (carbodiimide equivalent: 430) (Nisshinbo Co., Ltd.) (C2): Oxazoline compound Acrylic polymer EPOCROS with oxazoline groups and polyalkylene oxide chains (oxazoline group content = 4.5 mmol / g, manufactured by Nippon Shokubai Co., Ltd.) (C3): Epoxy compound Water-soluble polyglycerol polyglycidyl ether (C4): Melamine compounds Hexamethoxymethylolmelamine

[0129] binder (D1): Aqueous dispersion of urethane acrylate resin polymerized with the following composition Urethane acrylate consisting of hydrogenated xylylene diisocyanate, (di)pentaerythritol acrylate, hexanediol carbonate, and dimethylolpropanoic acid (D2): Aqueous dispersion of polyester resin polymerized with the following composition Monomer composition: (acid component) 2,6-naphthalenedicarboxylic acid / 5-sodium sulfoisophthalic acid / / (diol component) ethylene glycol / diethylene glycol = 92 / 8 / / 80 / 20 (mol%) (D3): Aqueous dispersion of acrylic resin polymerized with the following composition Emulsion polymer of ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylolacrylamide / acrylic acid = 65 / 21 / 10 / 2 / 2 (weight%) (emulsifier: anionic surfactant) (D4): Aqueous dispersion of urethane resin polymerized with the following composition A water dispersion of polyester-based urethane resin formed from isophorone diisocyanate units: terephthalic acid units: isophthalic acid units: ethylene glycol units: diethylene glycol units: dimethylolpropanoic acid units=12:19:18:21:25:5 (mol%)

[0130] Example 1 An 82 / 18 mass blend of polyester (1) and polyester (2) was used as the raw material for Layer A, and polyester (1) alone was used as the raw material for Layer B. These were fed into an extruder, heated and melted at 285°C, and co-extruded to a thickness ratio of A / B / A = 5 / 90 / 5, with Layer A split into two and Layer B as the outermost layer (surface layer) and Layer B as the middle layer. The resulting extrusion was then cooled and solidified while in close contact with a mirror-finished cooling drum at a surface temperature of 40-50°C to produce an unstretched polyethylene terephthalate film. This film was stretched 3.7 times in the longitudinal direction while passing through a group of heated rolls at 85°C to produce a uniaxially oriented film. Resin composition 1 shown in Table 1 below was applied to one side of this uniaxially stretched film, and then the film was introduced into a tenter stretching machine and stretched 4.3 times in the width direction at 100°C. After further heat treatment at 230°C, it was subjected to a 2% relaxation treatment in the width direction to obtain a 50 μm thick biaxially stretched polyester film having a resin layer with a film thickness (after drying) of 0.04 μm. The haze of the obtained laminated polyester film was 0.6%, and the surface resistivity of the resin layer side was 7 × 10 4 (Ω / □), the surface resistivity after processing the adhesive layer side is 4×1011 (Ω / □) The properties of this film are shown in Table 2 below.

[0131] Examples 2 to 15 A laminated polyester film was obtained in the same manner as in Example 1, except that the resin composition was changed to the composition shown in Table 1. The results are shown in Table 2.

[0132] Comparative Examples 1 to 6 A laminated polyester film was obtained in the same manner as in Example 1, except that the resin composition was changed to the composition shown in Table 1. The results are shown in Table 2.

[0133] [Table 1]

[0134] [Table 2]

[0135] From the results shown in Table 2, the surface resistivity of the resin layer side of the laminated polyester film in each example was 1 × 10 7 (Ω / □) or less, and the surface resistivity of the adhesive layer side after forming an adhesive layer on the resin layer is 1×10 12 (Ω / □) or less, and it was found that the antistatic performance was excellent even when an adhesive layer was provided using an adhesive that did not have antistatic properties. On the other hand, in each of the comparative examples, both surface resistivities exceeded the above range. Furthermore, in each example, the peeled area in the evaluation of adhesion was 70% or less, and it was found that the adhesion between the resin layer and the pressure-sensitive adhesive layer was excellent and could withstand practical use.

Claims

1. A polyester film having a resin layer substantially free of fluorine components on at least one surface thereof, and a surface resistivity of the resin layer side of the polyester film being 1×10 ７ Ω / □ or less, and when a 10 μm thick adhesive layer made of an acrylic adhesive that does not have antistatic properties is provided on the resin layer, the surface resistivity of the adhesive layer side is 1×10 １２ A laminated polyester film having a modulus of elasticity of Ω / □ or less.

2. The laminated polyester film according to claim 1, wherein the film having the pressure-sensitive adhesive layer provided on the resin layer has a peel area of ​​70% or less in the adhesion evaluation described below. (Adhesion evaluation) An acrylic adhesive layer having no antistatic properties and a thickness of 10 μm was formed on the resin layer, and 11 vertical and 11 horizontal cuts were made in the adhesive layer at 1 mm intervals using a cross cutter. Cellophane tape having a width of 18 mm was then attached, and the peel area was measured when peeled at a peel angle of 180 degrees.

3. 2. The laminated polyester film according to claim 1, wherein the resin layer contains (i) a polymer obtained by doping a compound consisting of thiophene or a thiophene derivative with another anionic compound.

4. 4. The laminated polyester film according to claim 3, wherein the resin layer contains (ii) one or more compounds or derivatives thereof selected from polyglycerin and / or alkylene oxide adducts of polyglycerin.

5. The laminated polyester film according to claim 4 , wherein the resin layer contains (iii) a binder resin.

6. The laminated polyester film according to claim 5 , wherein the resin layer contains (iv) a crosslinking agent.

7. 5. The laminated polyester film according to claim 4, wherein the (ii) one or more compounds or derivatives thereof selected from polyglycerin and / or alkylene oxide adducts of polyglycerin are polyglycerin represented by the following general formula (3): (n is an integer ranging from 2 to 20.)

8. 7. The laminated polyester film according to claim 6, wherein the crosslinking agent (iv) contains at least one compound selected from the group consisting of an oxazoline compound, an epoxy compound, a carbodiimide compound, and a melamine compound.

9. The laminated polyester film according to claim 6 , wherein the crosslinking agent (iv) is a carbodiimide compound.

10. The laminated polyester film according to claim 4, wherein the resin layer contains 30 to 65 mass % of the (ii) one or more compounds selected from polyglycerin and / or alkylene oxide adducts of polyglycerin or derivatives thereof.

11. The laminated polyester film according to claim 5, wherein the resin layer contains the binder resin (iii) in an amount of 20 to 50% by mass.

12. The laminated polyester film according to claim 6 , wherein the resin layer contains the crosslinking agent (iv) in an amount of 25% by mass or less.

13. A protective film for an image display device, comprising the laminated polyester film according to any one of claims 1 to 12.

14. A protective film for use in semiconductor manufacturing processes, comprising the laminated polyester film according to any one of claims 1 to 12.

15. An adhesive film comprising an adhesive layer made of an adhesive agent that does not have antistatic properties and provided on the resin layer of the laminated polyester film according to any one of claims 1 to 12.

16. A method for antistatic treatment of a film, comprising providing a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive that does not have antistatic properties on the resin layer of the laminated polyester film according to any one of claims 1 to 12.

17. Use of the laminated polyester film according to any one of claims 1 to 12 as a substrate for an adhesive film having an adhesive layer that does not have antistatic properties.

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