Laminated Polyester Film

Abstract

To provide a laminated polyester film having excellent anti-static property and transparency, and especially capable of suppressing reduction of anti-static property by friction.SOLUTION: A laminated polyester film has a resin layer formed from a resin composition containing the following constituent (A), constituent (B), and constituent (C) on at least one surface of a polyester film. The constituent (A) is at least one selected from the group consisting of (a1) a polymer obtained by doping a compound composed of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound composed of thiophene or a thiophene derivative. The constituent (B) is at least one selected from the group consisting of glycerol, polyglycerol, an alkylene oxide addition product of the glycerol or the polyglycerol, and a sugar alcohol and a sugar alcohol condensation product. The constituent (C) is a fluororesin particle.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] BACKGROUND ART Thermoplastic resin films with antistatic properties are used in a variety of fields, such as for protective films and cover tapes for electronic components, displays, and peripheral components of touch panels. As the thermoplastic resin film, polyethylene terephthalate (PET) film, which is a typical polyester film, and in particular biaxially oriented PET film, is widely used because of its excellent transparency, mechanical strength, heat resistance, and the like.

[0003] However, since polyester is generally an insulating resin, polyester films do not have antistatic properties as they are, and become charged when subjected to friction or peeling of the adhesive layer, resulting in problems such as adhesion of foreign matter and dust and electrostatic discharge problems. Therefore, a method of providing a polyester film with an antistatic resin layer on its surface has been investigated as a method of imparting antistatic properties to the polyester film. This method has the advantage of easily imparting antistatic properties to the film while making use of various basic properties of the film.

[0004] For example, Patent Document 1 proposes a method of coating a polyester film with a coating agent containing a vinyl resin whose constituent component is styrene sulfonic acid or a salt thereof, which is an ion-conductive antistatic agent. However, the ion conductive type has a problem in that it has insufficient antistatic properties.

[0005] Therefore, a method of using an electronically conductive type antistatic agent, which has superior antistatic properties compared to ionic conductive types, as an antistatic agent has been investigated. Among electronically conductive types, polythiophene compounds have excellent conductivity and are said to be able to exhibit high antistatic properties and transparency when applied to a film (for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 61-204240 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-173015 [Patent Document 3] JP 2016-60850 A Summary of the Invention [Problem to be solved by the invention]

[0007] In various applications of films that have been given antistatic properties, friction is likely to occur in various situations during the manufacturing and processing steps. For example, in a roll-to-roll process, as the number of processing steps increases, the frequency of contact, i.e., the frequency of rubbing, between the exposed antistatic layer and the guide roll increases. Furthermore, when a functional layer is laminated on a layer having antistatic properties, the layer having antistatic properties may come into contact with a bar for bar coating or a gravure roll for gravure coating, causing the layer having antistatic properties to be rubbed. Furthermore, as speeds increase to improve productivity, damage caused by friction also tends to increase.

[0008] The films disclosed in Patent Documents 2 and 3 sometimes suffer from a decrease in antistatic performance due to friction, making it difficult to achieve and maintain the excellent antistatic performance that the film inherently possesses.

[0009] Therefore, an object of the present invention is to provide a laminated polyester film that has excellent antistatic properties and transparency, and in particular, is capable of suppressing deterioration of antistatic performance due to friction. [Means for solving the problem]

[0010] The present inventors have conducted extensive research in light of the above-mentioned circumstances and have found that the above-mentioned problems can be solved by using a laminated polyester film provided with a resin layer having a specific composition, thereby completing the present invention. That is, the present invention has the following aspects.

[0011] [1] A laminated polyester film having a resin layer formed on at least one surface of a polyester film from a resin composition containing the following components (A), (B), and (C): Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): At least one member selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. Component (C): Fluorine resin particles [2] The laminated polyester film according to [1] above, wherein the component (B) contains a sugar alcohol. [3] The laminated polyester film according to [1] or [2] above, wherein the fluororesin particles of component (C) are at least one selected from the group consisting of tetrafluoroethylene-hexafluoropropylene copolymer and polytetrafluoroethylene. [4] The laminated polyester film according to any one of the above [1] to [3], wherein the average particle size of the fluororesin particles of the component (C) is 10 to 1000 nm. [5] The laminated polyester film according to any one of the above [1] to [4], wherein the content of the fluororesin particles of the component (C) is 0.1 to 20 mass% as a proportion of all non-volatile components in the resin composition. [6] The laminated polyester film according to any one of the above [1] to [5], wherein the resin composition further contains a binder resin as component (D). [7] The laminated polyester film according to the above [6], wherein the binder resin of the component (D) is at least one selected from the group consisting of polyurethane resins, polyester resins, and acrylic resins. [8] The laminated polyester film according to any one of the above [1] to [7], which has a haze value of 1.0% or less. [9] The surface resistivity measured on the surface of the resin layer is 1×10 6 The laminated polyester film according to any one of the above [1] to [8], which has a modulus of elasticity of less than Ω / □.

[10] The surface resistivity (R x ) and the surface resistivity (R Y ) and the ratio (R Y / R x ) is 4.0 or less. [Effects of the Invention]

[0012] According to the present invention, a laminated polyester film is provided which has excellent antistatic properties and transparency, and in particular, is capable of suppressing deterioration of antistatic properties due to friction, and is highly useful industrially. DETAILED DESCRIPTION OF THE INVENTION

[0013] An example of an embodiment of the present invention will be described in detail below. However, the present invention is not limited to the following embodiment, and can be modified and implemented as desired without departing from the gist of the present invention.

[0014] In this specification, the term "A to B" (A and B are any numbers) used to describe numerical values ​​means "greater than or equal to A and less than or equal to B" unless otherwise specified, and also includes the meanings "preferably greater than A" or "preferably smaller than B." In this specification, when it is stated that the content is "A or more" (A is any number) or "B or less" (B is any number), it also includes the intention that "it is preferably greater than A" or "it is preferably less than B." In the present invention, a combination of preferred embodiments is a more preferred embodiment. In this specification, the term "(meth)acrylic acid" means either or both of "acrylic acid" and "methacrylic acid." Similarly, the term "(meth)acrylate" means either or both of "acrylate" and "methacrylate," and the term "(meth)acryloyl" means either or both of "acryloyl" and "methacryloyl."

[0015] <<Laminated polyester film>> The laminated polyester film of the present invention has a resin layer formed from a resin composition containing specific components on at least one surface of the polyester film.

[0016] <Polyester film> The polyester film may have a single layer structure or a multilayer structure. When the polyester film has a multilayer structure, the polyester film may have a two-layer structure, a three-layer structure, or a four-layer structure or more, without departing from the gist of the present invention, and the number of layers is not particularly limited. The polyester film may be a non-stretched film (sheet) or a stretched film (sheet). Of these, a uniaxially or biaxially stretched film is preferred, and a biaxially stretched film is more preferred from the viewpoints of balance of mechanical properties, flatness, and thinning.

[0017] The polyester used as the raw material for the polyester film is not particularly limited and may be a homopolyester or a copolymer polyester. In the case of a homopolyester, examples include polyesters obtained by polycondensation of a dicarboxylic acid and a diol, with aromatic dicarboxylic acids being preferred as the dicarboxylic acid and aliphatic glycols being preferred as the diol.

[0018] The polyester film preferably contains polyester as a main component, and when the polyester film has a multi-layer structure, the main component resin of each layer is preferably polyester. The term "main component resin" refers to the resin that has the highest content among the resins constituting each layer, for example, a resin that accounts for 50% by mass or more, particularly 70% by mass or more, and even more particularly 80% by mass or more (including 100% by mass) of the resins constituting each layer.

[0019] Examples of the aromatic dicarboxylic acid include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, and phthalic acid. Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 1,4-cyclohexanedimethanol, neopentyl glycol, etc. Representative polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalate, polybutylene terephthalate, polybutylene-2,6-naphthalate, etc., and among these, polyethylene terephthalate (PET) is preferred.

[0020] Examples of the copolymer polyester include a copolymer polyester containing a third component other than the dicarboxylic acid (preferably aromatic dicarboxylic acid) that constitutes the polyester and the diol (preferably aliphatic glycol) that constitutes the diol as a copolymer component. For example, in the case of polyethylene terephthalate, the third component is a component other than terephthalic acid and ethylene glycol. Specifically, polyethylene terephthalate may contain about 30 mol % or less of dicarboxylic acid units other than terephthalic acid out of 100 mol % of dicarboxylic acid units, and may contain about 30 mol % or less of diol units other than ethylene glycol out of 100 mol % of diol units.

[0021] The intrinsic viscosity of the polyester is not particularly limited, but from the viewpoints of film-forming properties, productivity, etc., it is preferably 0.45 to 1.0 dL / g, more preferably 0.5 to 0.9 dL / g.

[0022] 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.

[0023] In order to suppress the amount of precipitation of oligomer components, the polyester film may be produced using a polyester having a low content of oligomer components as the raw material. As a method for producing a polyester having a low content of oligomer components, various known methods can be used, such as a method in which solid-state polymerization is carried out after the polyester is produced. The amount of oligomer component precipitation may be suppressed by using a polyester film having three or more layers and using a polyester raw material with a low content of oligomer components as the outermost layer of the polyester film. The polyester may be obtained by carrying out the esterification or transesterification reaction, followed by melt polycondensation at a higher reaction temperature under reduced pressure.

[0024] The polyester film may contain an ultraviolet absorber to improve the weather resistance of the film and prevent deterioration of the adherend (for example, optical members such as members constituting a display panel), etc. The ultraviolet absorber is not particularly limited as long as it is a compound that absorbs ultraviolet light and can withstand the heat applied in the manufacturing process of the polyester film.

[0025] The ultraviolet absorber may be an organic ultraviolet absorber or an inorganic ultraviolet absorber, but from the viewpoint of transparency, an organic ultraviolet absorber is preferred. The organic ultraviolet absorber is not particularly limited, but examples thereof include cyclic imino esters, benzotriazoles, and benzophenones. From the viewpoint of durability, cyclic imino esters and benzotriazoles are more preferred. One type of ultraviolet absorber may be used alone, or two or more types may be used in combination.

[0026] Particles may be blended into the polyester film primarily for the purposes of imparting lubricity and preventing scratches during each process. The type of particles to be blended is not particularly limited as long as they are capable of imparting lubricity. 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 part of a metal compound such as a catalyst during the polyester production process can also be used.

[0027] The shape of the particles to be used is not particularly limited, and any of spherical, blocky, rod-like, flat, etc. may be used. Furthermore, there are no particular limitations on the hardness, specific gravity, color, etc. These particle series may be used alone, or two or more types may be used in combination as needed.

[0028] The average particle size of the particles used is not particularly limited, but is usually 5 μm or less, preferably in the range of 0.01 to 3 μm. When the average particle size of the particles is 5 μm or less, the transparency of the film can be ensured, and the surface roughness of the film does not become too rough, which is preferable because it does not cause problems when various surface functional layers are formed in subsequent processes. When the average particle size of the particles is 0.01 μm or more, it is possible to ensure effects such as imparting easy slippage and preventing scratches. The average particle size can be determined by observing with a transmission electron microscope (TEM) to measure the particle sizes of 10 particles and averaging the measured values.

[0029] The particle content in the particle-containing layer is not particularly limited and is usually less than 5% by mass, preferably in the range of 0.0003 to 3% by mass. When no particles are contained or when the particle content is low, the polyester film has excellent transparency. On the other hand, when particles are contained in the above range, the polyester film has sufficient slip properties. Even when particles are contained, the transparency of the polyester film can be sufficiently ensured as long as the particle content is less than 5% by mass. When particles are incorporated into a polyester film, if the polyester film has a multilayer structure, for example, if the polyester film has a surface layer and an intermediate layer, it is preferable to incorporate particles into the surface layer. In this case, it is more preferable to use a multilayer structure having a particle-containing surface layer, an intermediate layer, and a particle-containing surface layer in this order. By incorporating particles into the surface layer, it is possible to effectively impart lubricity and the like while reducing the particle content in the entire polyester film.

[0030] The method for adding particles to a polyester film is not particularly limited, and any conventionally known method can be used. For example, in the case of a multi-layer polyester film, the particles can be added at any stage in the production of the polyester constituting each layer, but it is preferable to add the particles after the completion of the esterification or transesterification reaction.

[0031] In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. may be added to the polyester film as needed.

[0032] The thickness of the polyester film is not particularly limited as long as it is within a range that allows film formation, but is preferably in the range of 5 to 350 μm, more preferably 8 to 250 μm, even more preferably 10 to 200 μm, and particularly preferably 12 to 125 μm. When the polyester film has a multilayer structure, the thickness of the polyester film as a whole is within the above range.

[0033] Next, examples of producing polyester films will be specifically described, but the production methods are not limited to the following examples. For example, when producing a biaxially stretched 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 them on a rotating cooling drum (casting drum) to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to increase the adhesion between the sheet and the rotating cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method are preferably used. In this way, an unstretched sheet is obtained. In addition, when the polyester film has a multilayer structure, for example, a plurality of extruders can be used as an extruder to extrude the molten sheet from a die, and an unstretched sheet can be obtained as described above.

[0034] Next, the obtained unstretched sheet is stretched biaxially. First, the unstretched sheet is 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 film is stretched in a direction perpendicular to the first-stage stretching direction, in which case the stretching temperature is usually 70 to 170°C and the stretch ratio is 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 stretched film. In the stretching, a method of stretching in one direction in two or more stages can also be adopted. In such a case, it is preferable to perform the stretching so that the final stretch ratios in both directions are within the above ranges.

[0035] The polyester film can also be produced by a simultaneous biaxial stretching method, in which the unstretched sheet is simultaneously stretched and oriented in the longitudinal direction (machine direction) and the width direction under temperature control, typically at 70 to 120°C, preferably 80 to 110°C. The area stretching ratio is preferably 4 to 50 times, more preferably 7 to 35 times, and even more preferably 10 to 25 times. 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. The longitudinal direction (machine direction) of the film refers to the direction in which the film advances during the film production process, i.e., the winding direction of the film roll. The width direction refers to the direction parallel to the film surface and perpendicular to the longitudinal direction, i.e., the direction parallel to the central axis of the roll when the film is in a roll shape.

[0036] <Resin layer> The laminated polyester film of the present invention has a resin layer formed on at least one surface of the polyester film from a resin composition containing the following components (A), (B) and (C). Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): At least one member selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. Component (C): Fluorine resin particles

[0037] When producing a film with high transparency and low haze, the amount of particles that can be added to the polyester film substrate is limited, so particles, particularly silica particles, are often added to the resin layer in order to improve the handling and abrasion resistance of the film. On the other hand, even if the resin composition (excluding the above-mentioned component (C)) forming the resin layer of the laminated polyester film of the present invention does not contain particles or if silica particles are added for the above-mentioned purpose, the antistatic performance of the formed resin layer is reduced by friction. However, by including fluororesin particles as the above-mentioned component (C), the abrasion resistance of the formed resin layer is improved. Furthermore, by using the above-mentioned component (C) in combination with the above-mentioned components (A) and (B), the antistatic performance of the resin layer also tends to be improved. Although the details of the reason for this are not clear, the self-lubricating properties of the fluororesin particles are thought to contribute to this. In this specification, the term "abrasion resistance" refers to an evaluation based on the change in surface resistivity before and after abrasion treatment, measured by the method described in the examples below.

[0038] (Component (A)) The component (A) used in the present invention is at least one member selected from the group consisting of (a1) a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. When the resin composition of the present invention contains the component (A), it is possible to achieve both high antistatic properties and high transparency. Examples of the component (A) include those obtained by polymerizing a compound of the following formula (1) or (2) in the presence of a polyanion. The polymer (a1) and the polymer (a2) may be used in combination.

[0039] [ka]

[0040] In the above formula (1), R1 and R 2 each independently represents hydrogen or an aliphatic hydrocarbon group, alicyclic hydrocarbon group, or aromatic hydrocarbon group having 1 to 20 carbon atoms.

[0041] [ka]

[0042] In the above formula (2), n represents an integer of 1 to 4.

[0043] Examples of polyanions used in polymerization 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.

[0044] In the present invention, the compound of the above formula (2) in which n is 2 and polystyrene sulfonic acid is used as the polyanion is preferably used.

[0045] When these polyanions are acidic, they may be partially or completely neutralized. The base used for neutralization is preferably ammonia, organic amines, or alkali metal hydroxides.

[0046] The content of component (A) in the resin composition is preferably 0.1 to 30 mass%, more preferably 0.5 to 20 mass%, even more preferably 1 to 10 mass%, and particularly preferably 2 to 8 mass%, based on the total nonvolatile components in the resin composition. When the content of component (A) is equal to or less than the upper limit, the strength and transparency of the resin layer are good. On the other hand, when the content of component (A) is equal to or more than the lower limit, sufficient antistatic properties are obtained.

[0047] (Component (B)) The component (B) used in the present invention is at least one selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. When the resin composition of the present invention contains the component (B), it is possible to achieve both high antistatic properties and high transparency.

[0048] ((Glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin)) For example, at least one compound or derivative thereof selected from the group consisting of (b1) glycerin or a polyglycerin represented by the following formula (3) and (b2) an alkylene oxide adduct of the glycerin or the polyglycerin (b1) may be mentioned.

[0049] [ka] (In the formula, n represents an integer of 2 to 20.)

[0050] In the above formula (3), n is preferably 2 to 10, and more preferably in the range of 2 to 6. Within this range, the durability of the resin layer is further improved, and the antistatic properties are also good.

[0051] The alkylene oxide adduct of glycerin has a structure in which alkylene oxide is addition polymerized to the hydroxyl group of glycerin. 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).

[0052] The alkylene oxide adduct of glycerin only needs to have an alkylene oxide added to at least one of the hydroxyl groups of glycerin, and does not necessarily have to have an alkylene oxide added to all of the hydroxyl groups. When alkylene oxides are added to multiple hydroxyl groups of glycerin, the structures of the alkylene oxides may be the same or different. In the alkylene oxide adduct of polyglycerol, the structure of the alkylene oxide added to each hydroxyl group of the polyglycerol skeleton may be the same or different, and it is sufficient that an alkylene oxide is added to at least one hydroxyl group in the molecule, and it is not necessary that an alkylene oxide is added to all hydroxyl groups.

[0053] The alkylene oxide added to glycerin or polyglycerin is preferably ethylene oxide or propylene oxide. If the alkylene chain of the alkylene oxide is too long, the hydrophobicity becomes strong, dispersibility in the coating liquid deteriorates, and the antistatic property and transparency of the resin layer tend to deteriorate. From this viewpoint, ethylene oxide is more preferable. The number of alkylene oxides added is preferably in the range of 200 to 2,000, more preferably 250 to 1,000, and even more preferably 300 to 800, in terms of the number average molecular weight of the final compound.

[0054] The at least one compound or derivative thereof selected from the group consisting of glycerin, polyglycerin, and alkylene oxide adducts of the glycerin or polyglycerin may be used alone or in combination of two or more.

[0055] ((Sugar alcohol)) Sugar alcohols refer to chain polyhydric alcohols obtained by reducing the carbonyl group of aldoses, ketoses, etc., or cyclic polyhydric alcohols such as cyclitols. Specific examples include chain sugar alcohols such as erythritol, threitol, and other C4 sugar alcohols obtained by reducing monosaccharides; ribitol, arabinitol, xylitol, and other C5 sugar alcohols; and sorbitol, mannitol, iditol, talitol, and galactitol, and other C6 sugar alcohols. Other examples include cyclic sugar alcohols, such as cyclitols such as inositol. Further examples include disaccharide alcohols obtained by reducing disaccharides, such as maltitol, lactitol, and reduced isomaltulose. When the sugar alcohol has stereoisomers, all of the stereoisomers can be used as the sugar alcohol. The sugar alcohols may be used alone or in combination of two or more.

[0056] From the viewpoint of achieving both high antistatic properties and high transparency, the sugar alcohol is preferably a sugar alcohol having 4 to 12 carbon atoms, more preferably a sugar alcohol having 4 to 6 carbon atoms, and particularly preferably a sugar alcohol having 6 carbon atoms. Chain sugar alcohols are preferred. From the above viewpoint, it is preferable to use sorbitol among the sugar alcohols.

[0057] ((Sugar alcohol condensate)) The sugar alcohol condensate formally refers to a compound in which the hydroxyl groups of sugar alcohols are dehydrated and condensed within and / or between molecules, and examples thereof include sorbitan and isosorbide.

[0058] Component (B) preferably contains a sugar alcohol, and among sugar alcohols, it is more preferable to contain sorbitol, from the viewpoint of achieving excellent dispersibility and abrasion resistance, particularly abrasion resistance, in addition to antistatic properties and transparency.

[0059] The content of component (B) in the resin composition, as a proportion of all nonvolatile components in the resin composition, is preferably 10 to 99 mass%, more preferably 20 to 95 mass%, even more preferably 30 to 90 mass%, particularly preferably 50 to 90 mass%, and especially preferably 70 to 90 mass%. When the content of component (B) is equal to or less than the upper limit, dispersibility in the resin layer and transparency of the resin layer are sufficient. On the other hand, when the content of component (B) is equal to or greater than the lower limit, a uniform resin layer having sufficient antistatic properties, transparency, and film-forming properties can be obtained.

[0060] (Component (C)) Component (C) used in the present invention is fluororesin particles. In this specification, the term "fluororesin particles" refers to a fluororesin that has a particulate form in a dispersion medium such as water or alcohol at 25°C. In the present invention, the resin composition forming the resin layer contains fluororesin particles, which makes it possible to suppress the deterioration of antistatic performance due to friction, in particular, without impairing the excellent antistatic properties and transparency. Since the fluororesin particles are also particles, they can be provided with lubricity in the same manner as conventionally used silica particles.

[0061] Examples of fluororesin particles include polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Among these, from the viewpoint of versatility, at least one selected from the group consisting of FEP and PTFE is preferred, and FEP is more preferred.

[0062] The average particle size of the fluororesin particles in the dispersion solvent, as measured by dynamic light scattering, is preferably 10 to 1000 nm, more preferably 20 to 500 nm, even more preferably 50 to 300 nm, and particularly preferably 100 to 200 nm. If the average particle size is within this range, good coating appearance and improved strength of the resin layer can be expected. Commercially available fluororesin particles are available, such as "Neoflon FEP ND-110," "Polyflon PTFE D-210C," and "Neoflon PFA AD-2CRER," manufactured by Daikin Industries, Ltd.

[0063] The average particle size of the fluororesin particles is preferably 0.1 to 20 times the thickness of the resin layer, more preferably 0.3 to 10 times, and even more preferably 0.5 to 5 times. By having the particle size in this range, the handleability of the laminated polyester film is improved and the strength of the resin layer is improved.

[0064] The content of component (C) in the resin composition is preferably 0.1 to 20 mass%, more preferably 0.3 to 10 mass%, even more preferably 0.5 to 5 mass%, and particularly preferably 1 to 3 mass%, based on the total non-volatile components in the resin composition. When the content of component (C) is equal to or less than the upper limit, a good coating appearance and improved strength of the resin layer are achieved, whereas when the content of component (C) is equal to or greater than the lower limit, the handling of the film is improved, the strength of the resin layer is improved, and sufficient antistatic properties and abrasion resistance are obtained.

[0065] (Component (D)) In the present invention, the resin composition forming the resin layer preferably further contains a binder resin as component (D), and the binder resin is more preferably at least one selected from the group consisting of polyurethane resins, polyester resins, and acrylic resins. When the resin layer contains at least one resin selected from the group consisting of polyurethane resin, polyester resin, and acrylic resin, the film-forming property and transparency of the resin layer are improved.

[0066] ((Polyurethane resin)) The polyurethane resin is a polymer compound having a urethane bond in the molecule, and is preferably water-dispersible or water-soluble. In the present invention, a single type of polyurethane resin may be used, or two or more types of polyurethane resins may be used in combination.

[0067] To impart water dispersibility or water solubility, it is common and preferable to introduce hydrophilic groups such as hydroxyl groups, carboxyl groups, sulfonic acid groups, sulfonyl groups, phosphate groups, ether groups, etc. Among these hydrophilic groups, carboxyl groups and sulfonic acid groups are particularly preferred in terms of the physical properties of the resin layer and the adhesion between the resin layer and the polyester film.

[0068] One method for producing a urethane resin is by reacting a hydroxyl group-containing compound with an isocyanate group-containing compound. The hydroxyl group-containing compound used as a raw material is preferably a polyol, such as polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

[0069] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymer, polytetramethylene ether glycol, and polyhexamethylene ether glycol.

[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, 1,2-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 ... 2-methyl-2,4-pentanediol, 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, benzenedimethanol, bishydroxyethoxybenzene, alkyldialkanolamine, lactonediol, etc.

[0071] Examples of polycarbonate polyols include polycarbonate diols obtained by dealcoholization reaction of polyhydric alcohols with dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, etc., such as poly(1,6-hexylene) carbonate and poly(3-methyl-1,5-pentylene) carbonate.

[0072] Of these, polyester polyols are preferred.

[0073] Examples of polyisocyanate compounds used to obtain urethane resins 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, dicyclohexylmethane diisocyanate, and isopropylidenedicyclohexyl diisocyanate. These may be used alone or in combination.

[0074] A chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with isocyanate groups. Generally, chain extenders having two hydroxyl groups or two amino groups can be mainly used.

[0075] Examples of chain extenders having two hydroxyl groups include glycols such as aliphatic glycols such as ethylene glycol, propylene glycol, and butanediol; aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene; and ester glycols such as neopentyl glycol monohydroxypivalate.

[0076] Examples of chain extenders having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine; aliphatic diamines such as ethylenediamine, propanediamine, 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, 1,4-diaminocyclohexane, and 1,3-bisaminomethylcyclohexane.

[0077] ((Polyester resin)) The polyester resin may be composed of, as main components, for example, the following polycarboxylic acids and polyhydroxy compounds. Examples of polycarboxylic acids that can be used include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, potassium 2-sulfoterephthalate, sodium 5-sulfoisophthalate, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt, and ester-forming derivatives thereof. Polycarboxylic acids can be used alone or in combination of two or more. Examples of polyhydroxy compounds that can be used include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene ether glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, and potassium dimethylolpropionate. Polyhydroxy compounds can be used alone or in combination of two or more. One or more of these polycarboxylic acids and polyhydroxy compounds may be appropriately selected, and the polyester resin may be synthesized by a conventional polycondensation reaction.

[0078] By using a sulfonic acid group-containing polycarboxylic acid as part of the polycarboxylic acid, a product in which sulfonic acid groups are introduced into the polyester skeleton and neutralized to make it hydrophilic can be preferably used. For example, the above-mentioned sodium 5-sulfoisophthalate can be used as such a compound. The amount of the sulfonic acid group-containing polycarboxylic acid is usually 1 to 10 mol %, preferably 2 to 9 mol %, based on the total amount of polycarboxylic acid. By introducing an appropriate amount of sulfonic acid groups, the aqueous dispersion stability can be further improved.

[0079] ((acrylic resin)) The acrylic resin is a polymer made of polymerizable monomers including acrylic or methacrylic monomers, and may be a homopolymer, a copolymer, or a copolymer with a polymerizable monomer other than acrylic or methacrylic monomers. Also included are copolymers of the above (meth)acrylic (co)polymers with other polymers (such as polyesters and polyurethanes). Examples include block copolymers and graft copolymers. That is, the acrylic resin may be an acrylic-modified polyester resin or an acrylic-modified polyurethane resin. Polymers other than the above-mentioned (meth)acrylic (co)polymers also include polymers (and in some cases polymer mixtures) obtained by polymerizing polymerizable monomers having carbon-carbon double bonds in a polyester solution or polyester dispersion. Similarly, polymers (and in some cases polymer mixtures) obtained by polymerizing polymerizable monomers having carbon-carbon double bonds in a polyurethane solution or polyurethane dispersion are also included. Similarly, polymers (and in some cases polymer mixtures) obtained by polymerizing polymerizable monomers having carbon-carbon double bonds in other polymer solutions or dispersions are also included. In order to further improve the adhesion of the resin layer to the polyester film, the resin layer may contain a hydroxy group or an amino group.

[0080] The polymerizable monomer having a carbon-carbon double bond is not particularly limited, but typical compounds include, for example, various carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid, and salts thereof; various hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, monobutylhydroxyfumarate, and monobutylhydroxyitaconate; methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, and the like. various nitrogen-containing compounds such as (meth)acrylamide, diacetone acrylamide, or (meth)acrylonitrile; hydroxyl group-containing nitrogen-containing compounds such as N-methylol (meth)acrylamide; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, and vinyltoluene; various vinyl esters such as vinyl propionate; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; phosphorus-containing vinyl monomers; various vinyl halides such as vinyl chloride and vinylidene chloride; and various conjugated dienes such as butadiene.

[0081] Among the above acrylic resins, polymers obtained by polymerizing polymerizable monomers including acrylic and methacrylic monomers are preferred, and it is more preferred that the polymerizable monomers include alkyl(meth)acrylates. The resin composition is preferably diluted with a solvent to form a coating solution, as described below, and the solvent preferably contains water as the main solvent (50% by mass or more). That is, when the coating solution is made aqueous, the polymerizable monomer preferably has a hydrophilic group such as a hydroxyl group or a carboxyl group, from the viewpoint of facilitating dissolution or dispersion of component (D). Therefore, the acrylic resin is also preferably a polymer obtained by polymerizing polymerizable monomers including alkyl (meth)acrylate esters and hydrophilic group-containing monomers such as hydroxyl group-containing monomers and carboxyl group-containing monomers. The acrylic resin may be, for example, an emulsion polymer obtained by polymerizing a polymerizable monomer in the presence of a surfactant.

[0082] Component (D) preferably contains at least one of a polyurethane resin and a polyester resin, more preferably a polyester resin, and further preferably a polyester resin having a naphthalene skeleton from the viewpoint of the strength of the resin layer.

[0083] When the resin composition further contains component (D), its content is preferably 1 to 60 mass%, more preferably 2 to 30 mass%, and even more preferably 2 to 15 mass%, based on the total nonvolatile components in the resin composition. When the content of component (D) is equal to or less than the upper limit, sufficient antistatic properties are obtained. On the other hand, when the content of component (D) is equal to or greater than the lower limit, sufficient strength of the resin layer is obtained.

[0084] (Component (E)) In the present invention, the resin composition forming the resin layer may contain a crosslinking agent as component (E) for the purpose of improving the durability of the resin layer. As the crosslinking agent, various known crosslinking agents can be used, including, for example, melamine compounds, epoxy compounds, carbodiimide compounds, oxazoline compounds, isocyanate compounds, silane coupling compounds, etc. Among these, melamine compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds are preferred from the viewpoint of suppressing a decrease in antistatic properties after exposure to air, and melamine compounds and epoxy compounds are more preferred from the viewpoint of the strength of the resin layer. These may be used alone or in combination of two or more.

[0085] ((Melamine compounds)) The melamine compound is a compound having a melamine skeleton. For example, alkylolated melamine derivatives, compounds obtained by reacting alkylolated melamine derivatives with alcohol to partially or completely etherify them, and mixtures thereof can be used. Suitable alcohols for etherification include methanol, ethanol, isopropanol, 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.

[0086] ((Epoxy compound)) Epoxy compounds are compounds having an epoxy group in the molecule, such as condensates of epichlorohydrin with ethylene glycol, polyethylene glycol, glycerin, polyglycerin, bisphenol A, and other hydroxyl- or amino-group-containing compounds, polyepoxy compounds, diepoxy compounds, monoepoxy compounds, and glycidylamine compounds. Examples of polyepoxy compounds include sorbitol polyglycidyl ether, polyglycerin 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, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polytetramethylene glycol diglycidyl ether. Examples of monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether, and 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 the adhesion of the resin layer to the polyester film, polyether-based epoxy compounds are preferred. In terms of the amount of epoxy groups, polyepoxy compounds having three or more functional groups are preferred over difunctional ones.

[0087] ((Carbodiimide compound)) The 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 of the resin layer to the polyester film, a polycarbodiimide compound having two or more carbodiimide structures in the molecule is more preferred.

[0088] 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 both aromatic and aliphatic diisocyanates can be used. Specific examples include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate.

[0089] 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 within the above range improves the durability of the resin layer.

[0090] 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.

[0091] ((Oxazoline compound)) The oxazoline compound is a compound having an oxazoline group in the molecule, and a polymer containing an oxazoline group is particularly preferred. The oxazoline compound can be synthesized by homopolymerization of an addition-polymerizable oxazoline group-containing monomer or polymerization 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, and these can be used alone or in combination. Among these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially. The other monomers are not limited as long as they are copolymerizable with the addition-polymerizable oxazoline group-containing monomer. Examples include (meth)acrylic acid esters such as alkyl(meth)acrylates (the alkyl groups include 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)acrylamide, and N,N-dialkyl(meth)acrylamide. ) acrylamide (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 cyclohexyl group, or 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 may be used. The oxazoline compound may have a polyalkylene oxide chain such as a polyethylene oxide chain, and for example, a (meth)acrylate having a polyalkylene oxide chain may be used as another monomer. From the viewpoint of improving the adhesion of the resin layer to the polyester film, 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, even more preferably 3 to 8 mmol / g, and particularly preferably 4 to 6 mmol / g.

[0092] ((Isocyanate compounds)) The isocyanate compound is a compound having an isocyanate or an isocyanate derivative structure, such as a blocked isocyanate. Examples of isocyanates 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 such as biuretized products, isocyanurated products, uretdione products, and carbodiimide-modified products of these isocyanates. These may be used alone or in combination of two or more. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferred than aromatic isocyanates in order to prevent yellowing due to ultraviolet light.

[0093] When used in the form of a blocked isocyanate, examples of the blocking agent include bisulfites; phenolic compounds such as phenol, cresol, and ethylphenol; alcoholic compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol; active methylene compounds such as methyl isobutyrylacetate, 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; acid amide compounds such as acetanilide and acetic acid amide; and oxime compounds such as formaldehyde oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime. These may be used alone or in combination of two or more.

[0094] The isocyanate compound may be used alone or as a mixture or bond with various polymers. In terms of improving 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.

[0095] ((Silane coupling compound)) A silane coupling compound is an organosilicon compound that has an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. For example, epoxy group-containing compounds such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; (meth)acrylic group-containing compounds such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-2-(aminoethyl)- Examples of suitable compounds include amino group-containing compounds such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane; isocyanurate group-containing compounds such as tris(trimethoxysilylpropyl)isocyanurate and tris(triethoxysilylpropyl)isocyanurate; and mercapto group-containing compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane.

[0096] When the resin composition further contains component (E), its content is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, as a proportion of all nonvolatile components in the resin composition. By keeping component (E) within the above range, the durability of the resin layer is improved.

[0097] (Component (F)) In the present invention, the resin composition forming the resin layer preferably contains a surfactant as component (F) in order to improve the coatability onto the polyester film. As the surfactant, from the viewpoint of low foaming and not inhibiting the antistatic properties of the resulting resin layer, nonionic surfactants having one selected from polyalkylene oxide, polyglycerin, and derivatives thereof in their structure are more preferred, nonionic surfactants having polyalkylene oxide are even more preferred, and nonionic surfactants having polyethylene oxide are particularly preferred.

[0098] Furthermore, surfactants having a branched alkyl group-substituted acetylene structure, a fluoroalkyl group, or a fluoroalkenyl group in the hydrophobic portion are more preferred. Examples of surfactants having a branched alkyl group-substituted acetylene structure in the hydrophobic portion include nonionic surfactants having a structure having polyethylene oxide in the side chain, as shown in the following formula (4).

[0099] [ka]

[0100] In the above formula (4), m and n are positive numbers indicating the number of moles of ethylene oxide added. In the above formula (4), the average of m+n is preferably 1.3 or more and 30 or less, more preferably 2 or more and 20 or less, and even more preferably 4 or more and 13 or less.

[0101] The surfactants may be used alone or in combination of two or more kinds.

[0102] When the resin composition further contains component (F), the content thereof is preferably 0.1 to 20 mass%, more preferably 0.5 to 15 mass%, and even more preferably 2 to 10 mass%, as a proportion of all nonvolatile components in the resin composition. By keeping component (F) within the above range, good coatability is obtained, the transparency of the resin layer is maintained, and the durability of the resin layer is improved.

[0103] (Other ingredients) In addition to the above components, additives such as a reaction adjuster and an adhesion promoter may be further blended as appropriate within the scope of the present invention.

[0104] (solvent) The resin composition of the present invention preferably contains the above-mentioned components (A) to (C), as well as optionally added components (D) to (F), and other components, and is prepared as a coating solution by diluting the composition with a solvent. That is, the resin composition is applied to a polyester film as a liquid coating solution, and then dried and cured as necessary to form a resin layer. The above-mentioned components (A) to (C), as well as optionally added components (D) to (F), and other components constituting the resin composition, may be dissolved or dispersed in a solvent. When a coating liquid is prepared, the concentration of all nonvolatile components of the resin composition in the coating liquid is preferably 0.1 to 50% by mass. If the concentration is 0.1% by mass or more, a resin layer of the desired thickness can be efficiently formed. On the other hand, if the concentration is 50% by mass or less, the resin composition can be easily dissolved or dispersed in a solvent and can be easily applied. From the above viewpoints, the concentration of all nonvolatile components of the resin composition in the coating liquid is more preferably 0.5 to 30% by mass, and even more preferably 1 to 15% by mass.

[0105] The solvent is not particularly limited, and either water or an organic solvent can be used. From the viewpoint of environmental protection, it is preferable to use water as the main solvent (50% by mass or more). That is, the resin composition of the present invention is preferably used as an aqueous coating liquid to form a resin layer. The water content is preferably 60% by mass or more, more preferably 70% by mass or more. The aqueous coating liquid may contain a small amount of organic solvent. The specific amount of organic solvent should be less than that of water on a mass basis, for example, less than 30% by mass, preferably less than 20% by mass, more preferably less than 10% by mass of the solvent. Examples of organic solvents that can be used in combination with water include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether, and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; and amines such as dimethylethanolamine. These can be used alone or in combination. By appropriately selecting and adding these organic solvents to the aqueous coating liquid as needed, the stability and coatability of the coating liquid may be improved in some cases.

[0106] When only an organic solvent is used as the solvent, examples of such an organic solvent include aromatic hydrocarbons such as toluene; aliphatic hydrocarbons such as hexane, heptane, isooctane, etc.; esters such as ethyl acetate and butyl acetate; ketones such as ethyl methyl ketone and isobutyl methyl ketone; alcohols such as ethanol and 2-propanol; ethers such as diisopropyl ether and dibutyl ether, etc. These may be used alone or in combination, taking into consideration solubility, coatability, boiling point, etc.

[0107] It is presumed that the resin layer contains unreacted components (A) to (C) and other components, reacted compounds, or mixtures thereof.

[0108] <Method for producing laminated polyester film (method for forming resin layer)> The method for forming the resin layer in the present invention will be described below. 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, either of which can be used. 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 140 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.

[0109] In the present invention, the resin layer is preferably formed by in-line coating, which treats the surface of a polyester film during the film-forming process. In-line coating is a method of coating within the polyester film manufacturing process. Specifically, it is a method of coating at any stage from melt extrusion of polyester to stretching, heat setting, and winding up. Typically, coating is performed on any of the following: 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. For example, in sequential biaxial stretching, a method in which a uniaxially stretched film stretched in the longitudinal direction (machine direction) is coated and then stretched in the width direction is particularly advantageous. This method has the advantage of reducing production costs because film formation and resin layer formation can be carried out simultaneously. Furthermore, because stretching is carried out after coating, the thickness of the resin layer can be changed by adjusting the stretch ratio, making thin-film coating easier than with offline coating films. Furthermore, by providing a resin layer on the film before stretching, the resin layer can be firmly adhered to the polyester film by stretching the resin layer together with the polyester film. Furthermore, in the production of biaxially stretched polyester films, by stretching the film while gripping its edges with clips or the like, the film can be constrained in both the longitudinal and transverse directions, and high temperatures can be applied in the heat setting process while maintaining flatness and preventing wrinkles. 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 achieving stronger adhesion between the resin layer and the polyester film. Furthermore, a strong resin layer can be formed, improving performance such as migration resistance and moist heat resistance of various functional layers that can be formed on the resin layer.

[0110] Regardless of whether the coating is off-line or in-line, heat treatment and irradiation with active energy rays such as ultraviolet rays may be used in combination, if necessary. The 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.

[0111] The coating amount of the non-volatile component of the resin layer (after drying and stretching) is preferably 1 to 300 mg / m 2 , more preferably 5 to 150 mg / m 2 , and more preferably 10 to 75 mg / m 2 , particularly preferably 20 to 50 mg / m 2 The range is. If the coating amount of the resin layer is within the above range, sufficient antistatic properties can be obtained.

[0112] From the viewpoint of handleability, the total thickness of the laminated polyester film of the present invention is preferably 350 μm or less, more preferably 5 μm or more and 350 μm or less, even more preferably 8 μm or more and 250 μm or less, particularly preferably 10 μm or more and 200 μm or less, and especially preferably 12 μm or more and 125 μm or less.

[0113] <Physical properties of laminated polyester film> The haze of the laminated polyester film of the present invention is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 2.0% or less, and particularly preferably 1.0% or less. When the thickness is within the above range, the laminated polyester film of the present invention can be suitably used in applications requiring transparency.

[0114] The antistatic property of the laminated polyester film of the present invention can be evaluated by the surface resistivity measured on the surface of the resin layer provided on the polyester film surface. The lower the surface resistivity of the laminated polyester film surface (resin layer surface), the better the antistatic properties. The surface resistivity can be measured by the method described in the examples below. Surface resistivity is 1×10 12 If the resistance is less than 1×10 Ω / □, it can be said to have antistatic properties. 10 Ω / □ or less is considered to be good antistatic properties, and 1×10 8 If the resistance is less than Ω / □, it can be said that the antistatic performance is very good and is therefore preferable. 6 If it is less than Ω / □, it can be said that the antistatic performance is particularly good. There is no particular lower limit for the surface resistivity, but considering the cost required for manufacturing this film, a lower limit of 1 × 10 4 It is preferable to set it to Ω / □ or more.

[0115] In the laminated polyester film of the present invention, the surface resistivity of the resin layer is R x The surface of the resin layer was rubbed five times with a nonwoven fabric made of cupra at a load of 680 g, and the surface resistivity of the resin layer was measured as R Y The ratio of surface resistivity (R Y / R x The ratio of surface resistivities (R Y / R x The lower limit of ) is not particularly limited, but is, for example, 0.1 or more. The friction of the resin layer surface of the laminated polyester film can be measured using a rubbing tester according to the method described in the examples below. The ratio of the surface resistivities (R Y / R x ) within this range, deterioration of antistatic performance due to friction or the like can be suppressed, and the antistatic agent can be used without any practical problems.

[0116] The above-mentioned compounds and components in the resin layer can be analyzed by, for example, TOF-SIMS, ESCA, fluorescent X-ray analysis, or the like.

[0117] <<Applications>> The laminated polyester film of the present invention has excellent antistatic properties and transparency, and therefore can be suitably used for applications such as protective films and cover tapes for electronic components, displays, and peripheral members of touch panels, although the present invention is not limited to such applications. [Example]

[0118] 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.

[0119] <Evaluation method> (1) Intrinsic viscosity (IV) of polyester One gram of polyester, from which components incompatible with the polyester had been removed, was precisely weighed and dissolved in 100 mL of a 50 / 50 (mass ratio) phenol / tetrachloroethane mixed solvent. The intrinsic viscosity (IV) was measured at 30°C using a viscosity measuring device (Rigo Co., Ltd., model VMS-022UPC·F10).

[0120] (2) Average particle size of particles in polyester film The polyester films of the examples and comparative examples were observed using a transmission electron microscope (TEM) (Hitachi High-Technologies Corporation, model H-7650, accelerating voltage 100 kV), and the average particle size of 10 particles was taken as the average particle size.

[0121] (3) Non-volatile component concentration of coating solution Measurements were carried out using a halogen moisture meter ("HR73" manufactured by Mettler-Toledo K.K.) at 105°C for 60 minutes.

[0122] (4) Coating amount of resin layer (after drying and stretching) It was calculated from the concentration of nonvolatile components in the coating solution, the coating amount before drying derived from the amount of coating solution consumed, the transverse (width direction) stretching ratio, etc.

[0123] (5) Film haze Measurement was carried out in accordance with JIS K 7136:2000 using a haze meter ("HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0124] (6) Surface resistivity of the resin layer The laminated polyester films obtained in the Examples and Comparative Examples were conditioned for 30 minutes in a measurement atmosphere of 23°C and 50% RH, and then the surface resistivity of the resin layer surface was measured using a four-point ESP probe in a low resistivity meter (Loresta GP MCP-T600 manufactured by Nitto Seiko Analytech Co., Ltd.). The resistivity correction factor (RCF value) was set to a constant value of 4.235.

[0125] (7) Friction treatment of the resin layer Using a rubbing tester (manufactured by Ohira Rika Kogyo Co., Ltd.), four layers of 5 cm x 10 cm cupra nonwoven fabric ("Bencott M-3II" manufactured by Ozu Sangyo Co., Ltd.) were wrapped around a 5 cm x 7 cm flat friction element without slack, and the resin layer surface of the laminated polyester film obtained in the examples and comparative examples was rubbed five times back and forth (within a 15 cm length range) with a load of 680 g, and then the surface resistivity was measured. The method for measuring the surface resistivity is as described in (6). The surface resistivity of the resin layer obtained in (6) is R x The surface resistivity of the resin layer after friction treatment is R Y The ratio of surface resistivity (R Y / R x ) was calculated and used as the abrasion resistance.

[0126] (8) Average particle size of fluororesin particles or silica particles The average particle size was measured using a particle size distribution analyzer ("ELSZ-2000ZS" manufactured by Otsuka Electronics Co., Ltd.) based on the dynamic light scattering method, with the concentration of the sample adjusted with pure water to obtain the optimum light intensity. The particle size in the present invention is the particle size at 50% of the cumulative volume (D50) measured in this manner.

[0127] <Materials used> The polyester raw materials for the polyester films used in the examples and comparative examples are as follows:

[0128] [Polyester (1)] Substantially particle-free polyethylene terephthalate with an intrinsic viscosity of 0.64 dL / g

[0129] [Polyester (2)] Polyethylene terephthalate with an intrinsic viscosity of 0.65 dL / g containing 0.2% by mass of amorphous silica with an average particle size of 2.4 μm

[0130] The following components were used as the resin composition for forming the resin layer. (Component (A)) A1: Conductive agent "AS-G1" (manufactured by Shin-Etsu Polymer Co., Ltd., mainly composed of polyethylenedioxythiophene and polystyrene sulfonic acid) was neutralized with concentrated ammonia water to a pH of 9.

[0131] (Component (B)) B1: Polyglycerol in which the average n is 4 in formula (3) B2: A compound in which an average of four polyethylene oxide molecules are added to a polyglycerin skeleton in which the average n is 2 in formula (3). [ka] B3: Sorbitol

[0132] (Component (C)) C1: Water dispersion of FEP particles with an average particle size of 119 nm ("Neoflon FEP ND-110" manufactured by Daikin Industries, Ltd.) C2: PTFE particle water dispersion with an average particle size of 168 nm ("Polyflon PTFE D-210C" manufactured by Daikin Industries, Ltd.) The average particle diameters are all values ​​measured by the method (8) above.

[0133] (Component (D)) D1: Aqueous dispersion of polyester resin copolymerized with the following composition Monomer composition: (Acid component) 2,6-naphthalenedicarboxylic acid / sodium 5-sulfoisophthalate = 92 / 8 (molar ratio) (Diol component) Ethylene glycol / diethylene glycol = 80 / 20 (molar ratio)

[0134] (Component (E)) E1: Polymethylolated melamine E2: Polyglycerin polyglycidyl ether

[0135] (Component (F)) F1: A nonionic surfactant having a structure having polyethylene oxide in the side chain, in which the average of m+n in formula (4) is 10 [ka] F2: A fluorine-based nonionic surfactant with a structure having a branched perfluoroalkenyl group in the hydrophobic group and a polyethylene oxide chain (average chain length 8 units) in the hydrophilic group.

[0136] (Comparison component (G)) G1: Spherical silica particles with an average particle size of 67 nm The average particle size is a value measured by the method (8) above.

[0137] Example 1 A 92 / 8 weight 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, and the resulting extrusion was performed in such a way that the thickness ratio was A / B / A = 5 / 90 / 5. The film was then cooled and solidified while in close contact with a mirror-finished cooling drum with a surface temperature of 40-50°C, producing an unstretched film. This film was stretched 3.7 times in the longitudinal direction while passing through a group of heated rolls at 85°C, producing a uniaxially stretched film. Resin composition 1 (coating solution, non-volatile component concentration 4.4% by mass) having the composition shown in Table 1 below was applied to one side of this uniaxially stretched film, and then this film was introduced into a tenter stretching machine and stretched 4.3 times in the width direction at 100°C, and further subjected to heat treatment at 230°C, followed by a 2% relaxation treatment in the width direction, resulting in a coating weight of 46 mg / m after drying. 2 A biaxially stretched film having the above resin layer and a thickness of 50 μm was obtained, thereby obtaining a laminated polyester film of Example 1. The evaluation results of this laminated polyester film are shown in Table 2 below.

[0138] (Examples 2 to 6, Comparative Examples 1 and 2) The laminated polyester films of Examples 2 to 6 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the resin composition for forming the resin layer was changed to the composition shown in Table 1. The evaluation results are shown in Table 2.

[0139] [Table 1]

[0140] [Table 2]

[0141] The laminated polyester films obtained in Examples 1 to 6 of the present invention had excellent antistatic properties and transparency (low haze value), and in particular, were able to suppress the deterioration of antistatic performance due to friction.Comparative Example 1, which did not contain fluororesin particles as component (C), and Comparative Example 2, which added silica particles instead of fluororesin particles, were inferior in terms of friction resistance compared to Examples 1 to 6. Therefore, the laminated polyester film of the present invention has excellent antistatic properties and transparency, as well as excellent abrasion resistance, and is able to exhibit and maintain the excellent antistatic properties inherent to the film, making it highly valuable in industrial applications.

Claims

1. A laminated polyester film having a resin layer formed on at least one surface of a polyester film from a resin composition containing the following components (A), (B), and (C): Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): Sugar alcohol Component (C): Fluorine resin particles

2. A laminated polyester film having a resin layer formed on at least one surface of the polyester film from a resin composition containing the following components (A), (B) and (C): Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): At least one selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. Component (C): Fluorine resin particles, which are at least one selected from the group consisting of tetrafluoroethylene-hexafluoropropylene copolymer and polytetrafluoroethylene.

3. A laminated polyester film having a resin layer formed on at least one surface of the polyester film from a resin composition containing the following components (A), (B) and (C): Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): At least one selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. Component (C): Fluorine resin particles having an average particle size of 10 to 1000 nm

4. A laminated polyester film having a resin layer formed on at least one surface of the polyester film from a resin composition containing the following components (A), (B), (C) and (D): Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): At least one selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. Component (C): Fluorine resin particles Component (D): Binder resin

5. A laminated polyester film having a resin layer formed from a resin composition containing the following components (A), (B) and (C) on at least one surface of the polyester film, wherein the surface resistivity measured on the surface of the resin layer is less than 1 x 10 6 Ω / □. Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): At least one selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. Component (C): Fluorine resin particles

6. A laminated polyester film having, on at least one surface of the polyester film, a resin layer formed from a resin composition containing the following components (A), (B), and (C), wherein the ratio (R Y / R X ) of the surface resistivity (R X ) of the resin layer to the surface resistivity (R Y ) of the resin layer after the surface of the resin layer is rubbed five times with a cupra nonwoven fabric at a load of 680 g is 4.0 or less. Component (A): (a1) at least one selected from the group consisting of a polymer obtained by doping a compound made of thiophene or a thiophene derivative with another anionic compound, and (a2) a self-doped polymer having an anionic group in a compound made of thiophene or a thiophene derivative. Component (B): At least one selected from the group consisting of glycerin, polyglycerin, alkylene oxide adducts of the glycerin or polyglycerin, sugar alcohols, and sugar alcohol condensates. Component (C): Fluorine resin particles

7. The laminated polyester film according to any one of claims 2 to 6, wherein the component (B) comprises a sugar alcohol.

8. The laminated polyester film according to any one of claims 1 and 3 to 7, wherein the fluororesin particles of the component (C) are at least one selected from the group consisting of tetrafluoroethylene-hexafluoropropylene copolymer and polytetrafluoroethylene.

9. 9. The laminated polyester film according to claim 1, wherein the average particle size of the fluororesin particles of the component (C) is 10 to 1,000 nm.

10. 10. The laminated polyester film according to claim 1, wherein the content of the fluororesin particles of component (C) is 0.1 to 20 mass% as a ratio of all non-volatile components in the resin composition.

11. The laminated polyester film according to any one of claims 1 to 3 and 5 to 10, wherein the resin composition further contains a binder resin as component (D).

12. 12. The laminated polyester film according to claim 4, wherein the binder resin of the component (D) is at least one resin selected from the group consisting of polyurethane resins, polyester resins, and acrylic resins.

13. The laminated polyester film according to any one of claims 1 to 12, which has a haze value of 1.0% or less.

14. The surface resistivity measured on the surface of the resin layer is 1×10 ６ The laminated polyester film according to any one of claims 1 to 4 and 6 to 13, having a modulus of elasticity of less than Ω / □.

15. The surface resistivity (R Ｘ ) and the surface resistivity (R Ｙ ) and the ratio (R Ｙ / R Ｘ 15. The laminated polyester film according to claim 1, wherein the value of (a) is 4.0 or less.

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