Release film

Abstract

A release film comprising a resin layer (A) on one surface of a base material film, and comprising a resin layer (B) on the other surface of the base material film, the resin layer (A) containing a silicone-resin-based release agent and having a thickness of 0.2-2.0 μm, and the resin layer (B) containing a non-silicone-resin-based release agent.　The present invention makes it possible to provide a release film and a release laminate in which the peel characteristics of release layers does not readily change due to blocking even while ultra-easy peeling is realized with respect to various adhesive agents.

Description

Technical Field

[0001] The present invention relates to a release film, an adhesive sheet, and a method of using the adhesive sheet.

Background Art

[0002] Conventionally, release films based on polyester films have excellent properties such as mechanical strength, dimensional stability, chemical resistance, and optical properties, and are used in various applications because of their excellent cost performance. For example, they are used in various applications such as for polarizing plates for liquid crystal displays (hereinafter abbreviated as LCDs), for manufacturing retardation films, for manufacturing components of plasma display panels (hereinafter abbreviated as PDPs), for manufacturing components of organic electroluminescence (hereinafter abbreviated as organic EL), and various optical applications.

[0003] In recent years, in applications using an adhesive layer, there are cases where durability is required more than ever. For example, when an adhesive layer is used for bonding components of a touch panel mounted inside an automobile, in this application, because it is used outdoors, it is necessary that the members are firmly adhered to each other even when exposed to a high-temperature atmosphere in summer or a low-temperature environment in winter. Therefore, as the durability of the adhesive layer itself has improved, the adhesive force of the adhesive layer itself has tended to be even stronger than before. Therefore, conventionally, a general-purpose light-peeling type release film may become difficult to peel off from the adhesive layer, and further light peeling is required. In addition, as a trend of recent adhesives, an adhesive layer with a low elastic modulus is preferred in terms of better step absorption. When dealing with an adhesive layer with a low elastic modulus, the surface of the adhesive layer is likely to be deformed when the release film is peeled off, and a stringing phenomenon may occur. Therefore, further light peeling, so-called ultra-light peeling, is required for the release film.

[0004] As a countermeasure for ultra-light peeling of the release film, there is a method of increasing the thickness of the release layer to achieve light peeling. However, with this method, depending on the type of release agent used, transfer components derived from the release layer may adhere to the surface of the adhesive layer, making it difficult to obtain the desired adhesive force in some cases.

[0005] On the other hand, when using a release agent with low transferability to suppress the transfer from the release layer, the adhesion of transfer components to the surface of the adhesive layer is reduced. However, when the release layer is thickly coated, the slipperiness of the surface of the release layer is poor. When the film is wound into a roll, the films may block each other, and in the underwound part of the roll where pressure is applied by the film, the peeling force of the release layer may become heavy or the appearance of the surface of the release layer may deteriorate. To solve this problem, a method of preventing blocking of the release film by incorporating fine particles into the release layer has been studied. (Patent Documents 1, 2).

[0006] As another study, a proposal has been made to provide a resin layer containing particles on the surface of the film opposite to the surface where the release layer of the film is provided (Patent Document 3).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, when fine particles are incorporated into the release layer, blocking can be prevented. On the other hand, it is difficult to stably have the fine particles present on the surface of the release layer, and the release layer itself also becomes brittle. Along with the fall of the particles, etc., the peeling characteristics of the release layer may change, and it may be difficult to obtain a stable peeling force in some cases.

[0009] In addition, when a resin layer containing particles is provided on the surface opposite to the surface on which the release layer is provided, blocking can be prevented. However, depending on the degree of unevenness formation, the unevenness of the particles contained in the resin layer may be transferred to the release layer during the formation of the film roll, the release characteristics of the release layer may change, and it may be difficult to obtain a stable release force. The present invention has been made in view of the above actual situation, and the problem to be solved is to provide a release film and a film laminate in which the release characteristics of the release layer are less likely to change due to blocking while achieving ultra-light releasability with respect to various adhesives. [Means for Solving the Problems]

[0010] In view of the above actual situation, the present inventors conducted intensive studies and as a result, found that the above problems can be solved by using a release film having a specific configuration, and thus completed the present invention. That is, the present invention provides the following [1] to

[28] . [1] A release film having a resin layer (A) on one surface of a base film and a resin layer (B) on the other surface, wherein the resin layer (A) contains a silicone resin-based release agent and has a thickness of 0.2 to 2.0 μm, and the resin layer (B) contains a non-silicone resin-based release agent. [2] A release film having a resin layer (A) on at least one side of a base film, wherein the resin layer (A) is a cured product of a resin layer composition containing a curable silicone resin and a light release agent, and the light release agent has a dimethylsiloxane skeleton (DM) represented by the following formula (I) and a methylphenylsiloxane skeleton (MP) represented by the following formula (II), and has a thickness of 0.2 to 1.5 μm. [Chemical formula] [Chemical formula] [3] The maximum cross-sectional height (Rt) of the film surface on the side opposite to the surface where the resin layer (A) is provided is 2.0 μm or less, and the release film according to [2] above. [4] The surface of the base film on the side opposite to the surface where the resin layer (A) is provided includes a polyester layer containing 0.4 to 1.0% by mass of particles having an average particle diameter of 1 to 6 μm, and the release film according to [2] or [3] above. [5] The mass average molecular weight of the light release agent is 10,000 or more and 100,000 or less, and the release film according to any one of [2] to [4] above. [6] The elastic modulus at 25°C measured using a nanoindentation device for the resin layer (A) is 500 MPa or less, and the release film according to any one of [1] to [5] above. [7] The non-silicone resin-based release agent is at least one selected from the group consisting of wax, long-chain alkyl group-containing compounds, and fluorine compounds, and the release film according to [1] or [6] above. [8] The content of the release agent in the non-volatile components of the resin layer (B) is 10 to 70% by mass, and the release film according to [1], [6], or [7] above. [9] The resin layer (B) substantially does not contain particles, and the release film according to any one of [1] and [6] to [8] above.

[10] The normal release force of the resin layer (A) measured by the following evaluation method is 5 g / 25 mm or less, and the release film according to any one of [1] to [9] above. <Evaluation method> After sticking an acrylic adhesive tape ("No. 7475" manufactured by Tesa) on the resin layer (A) surface of the release film, cut it into a size of 25 mm × 150 mm and leave it at room temperature for 1 hour. The release force is measured by peeling at 180° under the condition of a tensile speed of 0.3 m / min.

[11] A primer layer is provided between at least one of the resin layer (A) or the resin layer (B) and the base film, and the release film according to any one of [1] and [6] to

[10] above.

[12] The primer layer is an antistatic layer, and the release film according to

[11] above.

[13] The release film according to

[11] or

[12] above, wherein the undercoat layer contains the following compounds (A) to (C). (A) A polymer doped with another anion compound in a compound composed of thiophene or a thiophene derivative, or a polymer having an anion group in a compound composed of thiophene or a thiophene derivative and self-doped (B) A polyhydroxy compound (C) One or more compounds selected from the group consisting of a polyurethane resin, a polyester resin, and an acrylic resin

[14] The surface resistivity of at least one surface of the resin layer (A) or the resin layer (B) is 1×10 12 Ω / □ or less. The release film according to any one of [1] and [6] to

[13] above.

[15] The release film according to any one of [1] to

[14] above, wherein the base film is a polyester film.

[16] The release film according to

[15] above, wherein the polyester film has a three-layer structure.

[17] The release film according to any one of [1] to

[16] above, wherein the post-press re-peeling rate of the resin layer (A) evaluated by the following method is 100% or less. <Evaluation method> After sticking an acrylic adhesive tape ("No. 7475" manufactured by Tesa) on the surface of the resin layer (A), it is cut into a size of 25 mm × 150 mm and left at room temperature for 1 hour. The peeling force peeled at 180° under the condition of a tensile speed of 0.3 m / min is taken as (F1). Next, it is laminated so as to contact the surface of the resin layer (A), and a press treatment is performed at a temperature of 40°C, a humidity of 90% RH, and a load of 1 MPa for 20 hours. After sticking an acrylic adhesive tape ("No. 7475" manufactured by Tesa) on the surface of the resin layer (A) after the treatment, it is cut into a size of 25 mm × 150 mm and left at room temperature for 1 hour. The peeling force peeled at 180° under the condition of a tensile speed of 0.3 m / min is taken as (F2). The post-press re-peeling rate is obtained by the following formula. Post-press re-peeling rate (%) = (F2 - F1) / F1 × 100

[18] The mold release film according to any one of [1] to

[17] above, wherein the center line average roughness (Ra(A)) of the surface of the resin layer (A) is 30 nm or less.

[19] The mold release film according to any one of [1] or [6] to

[18] above, wherein the center line average roughness (Ra(B)) of the surface of the resin layer (B) is 60 nm or less.

[20] An adhesive sheet including another mold release film via an adhesive layer and the mold release film according to any one of [1] to

[19] above.

[21] The adhesive sheet according to

[20] above, wherein the adhesive layer is formed from an acrylic adhesive composition.

[22] The adhesive sheet according to

[20] or

[21] above, wherein the elastic modulus (25°C) of the adhesive layer is 6.0 MPa or less.

[23] The adhesive sheet according to any one of

[20] to

[22] above, wherein the adhesive layer contains 2-ethylhexyl acrylate and / or butyl acrylate.

[24] The adhesive sheet according to any one of

[20] to

[23] above, which is for an optical transparent adhesive sheet.

[25] The mold release film according to any one of [1] to

[19] above, which is for a display.

[26] The mold release film according to any one of [1] to

[19] above, which is for a foldable display.

[27] A method of using the adhesive sheet according to any one of

[20] to

[23] above, wherein after peeling off the other mold release film, the surface of the adhesive layer that is exposed is bonded to an optical member.

[28] The method of using the adhesive sheet according to

[27] above, wherein the optical member is a polarizing plate or a touch sensor. [Effect of the Invention]

[0011] According to the mold release film of the present invention, it is possible to provide a mold release film and a film laminate in which, while realizing ultra-light peelability with respect to various adhesives, the peel characteristics of the release layer are less likely to change due to blocking. [Embodiments for Carrying Out the Invention]

[0012] Hereinafter, an example of an embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiments described below, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[0013] <<<Release film>>> A release film according to an example of an embodiment of the present invention (hereinafter, may be referred to as "this release film") is a release film provided with a resin layer (A) on one surface of a base film and a resin layer (B) on the other surface. The release film is formed into a wound roll-shaped release film (release film roll), and it is preferably stored in the form of a release film roll. In that case, the release layer (A) may be disposed on either the inner or outer side of the roll.

[0014] In this release film, the resin layer (A) on one surface is characterized by containing a silicone resin-based release agent. The thickness of the resin layer (A) is 0.2 to 2.0 μm, and the elastic modulus of the resin layer (A) at 25°C measured using a nanoindenter device is preferably 500 MPa or less. Also, the resin layer (B) on the other film surface is characterized by containing a non-silicone resin-based release agent. When the release film having the above configuration is formed into a roll shape, the surface of the resin layer (A) is overlapped with the surface of the resin layer (B). At this time, the resin layer (B) reduces the damage caused by adhesion to the surface of the resin layer (A), suppresses blocking, and can prevent the delamination of the resin layer (A) and the deterioration of the surface appearance in the underwinding portion of the roll where more pressure is applied to the film. Also, while realizing ultra-light peelability, the resin layer (A) has good adhesion to the base film by substantially not containing particles, and further, since there is no particle dropout, the transferability to an adhesive tape or the like can be reduced.

[0015] <<Base film>> The base film of this release film is not particularly limited as long as it is in the form of a film. For example, it may be made of paper, resin, metal, etc. Among these, from the viewpoints of mechanical strength and flexibility, it is preferably made of resin. Examples of the resin base film include films formed by shaping polymers such as polyethylene, polypropylene, polyester, polystyrene, polycarbonate, polyethersulfone, polyamide, and polyimide into a film shape. Also, as long as it can be formed into a film, those obtained by mixing these materials (polymer blend) or those obtained by combining constitutional units (copolymer) may be used. Among the films exemplified above, a polyester film is particularly preferred because of its excellent physical properties such as heat resistance, flatness, optical properties, and strength.

[0016] <Polyester Film> The polyester film constituting the laminated film of the present invention may have a single-layer structure or a multi-layer structure. In addition to a two-layer or three-layer structure, as long as it does not exceed the gist of the present invention, it may have a multi-layer structure of four layers or more, and is not particularly limited. In the present invention, it is preferably a polyester film having at least a three-layer structure. Also, as the polyester film, a biaxially stretched polyester film is preferred from the viewpoints of thinning and dimensional stability.

[0017] The polyester used in the present invention may be a homopolyester or a copolyester. When it is composed of a homopolyester, it is preferably obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyesters include polyethylene terephthalate. On the other hand, examples of the dicarboxylic acid component of the copolyester include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (e.g., p-oxybenzoic acid), and examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexanedimethanol, and neopentyl glycol.

[0018] When it is composed of a copolyester, examples include those obtained by polycondensing a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (e.g., p-oxybenzoic acid), and examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexanedimethanol, and neopentyl glycol. The copolyester preferably contains a third component of 30 mol% or less based on the total of the dicarboxylic acid component and the glycol component. Note that the main component resin means the resin with the largest mass ratio among the resins constituting the present polyester film, and it accounts for 50% by mass or more, or 75% by mass or more, or 90% by mass or more, or 100% by mass of the resins constituting the present polyester film.

[0019] As the polymerization catalyst for the above polyester film, there are no particular restrictions, and conventionally known compounds can be used. For example, antimony compounds, titanium compounds, germanium compounds, manganese compounds, aluminum compounds, magnesium compounds, calcium compounds, etc. can be mentioned. Among these, titanium compounds and germanium compounds are preferred because they have high catalytic activity, can perform polymerization in a small amount, have a small amount of metal remaining in the film, and the brightness of the film is high. Further, since germanium compounds are expensive, titanium compounds are more preferred.

[0020] In the case of polyester using a titanium compound, the titanium element content is preferably in the range of 50 ppm or less, more preferably 1 to 20 ppm, and still more preferably 2 to 10 ppm. When the content of the titanium compound is too large, the deterioration of the polyester may be promoted in the process of melt-extruding the polyester, and a film with a strong yellow color may be obtained. On the other hand, when the content is too small, the polymerization efficiency is poor, the cost may increase, and a film with sufficient strength may not be obtained. Further, when using polyester with a titanium compound, for the purpose of suppressing deterioration in the melt-extrusion process, it is preferable to use a phosphorus compound to lower the activity of the titanium compound. Considering the productivity and thermal stability of the polyester, orthophosphoric acid is preferable as the phosphorus compound. The phosphorus element content is preferably in the range of 1 to 300 mass ppm, more preferably 3 to 200 mass ppm, and still more preferably 5 to 100 mass ppm with respect to the amount of polyester to be melt-extruded. When the content of the phosphorus compound is below the above upper limit value, it will not cause gelation or foreign matter, and when it is above the above lower limit value, the activity of the titanium compound can be sufficiently lowered, coloring can be suppressed, and a film with a yellow color will not be obtained.

[0021] In order to suppress the precipitation amount of the oligomer component, a film may be produced using polyester with a small content of the oligomer component as a raw material. As a method for producing polyester with a small content of the oligomer component, various known methods can be used, for example, a method of performing solid-phase polymerization after polyester production, etc.

[0022] In addition, the polyester film may have a three-layer or more structure, and the outermost layer of the polyester film may be a layer made of a polyester raw material with a low content of oligomer components, thereby suppressing the precipitation amount of the oligomer components. Further, the polyester may be obtained by increasing the reaction temperature and performing melt polycondensation under reduced pressure after the esterification or transesterification reaction.

[0023] It is also possible to incorporate an ultraviolet absorber into the polyester film to improve the weather resistance of the film and prevent deterioration of adherends (such as liquid crystals). The ultraviolet absorber is a compound that absorbs ultraviolet rays and is not particularly limited as long as it can withstand the heat added in the polyester film manufacturing process.

[0024] As the ultraviolet absorber, there are organic ultraviolet absorbers and inorganic ultraviolet absorbers. From the viewpoint of transparency, organic ultraviolet absorbers are preferred. The organic ultraviolet absorbers are not particularly limited, and examples include cyclic iminoester-based, benzotriazole-based, benzophenone-based, etc. From the viewpoint of durability, cyclic iminoester-based and benzotriazole-based are more preferred. It is also possible to use two or more kinds of ultraviolet absorbers in combination.

[0025] In the polyester layer of the polyester film, it is also possible to incorporate particles mainly for the purpose of imparting slipperiness and preventing the occurrence of scratches in each process. When incorporating particles, the type of particles to be incorporated is not particularly limited as long as they can impart slipperiness. Specific examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, zirconium oxide, titanium oxide, etc., and organic particles such as acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, benzoguanamine resin, etc. Further, during the polyester manufacturing process, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst can also be used. Among these, silica particles and calcium carbonate particles are preferred in terms of being particularly effective even in small amounts.

[0026] Also, the average particle size is preferably in the range of 0.01 to 5 μm, more preferably 0.03 to 4 μm, and even more preferably 0.05 to 3.0 μm. When the average particle size is below the above upper limit, the haze of the film can be kept low, and the film has slipperiness.

[0027] Furthermore, the particle content in the polyester layer of the polyester film is preferably 5% by mass or less, more preferably in the range of 0.001 to 3% by mass, even more preferably 0.01 to 1% by mass, and particularly preferably 0.05 to 0.5% by mass. When there are no particles or the number of particles is small, the transparency of the film is high and it becomes a good film. However, in order to prevent a decrease in slipperiness, it may be necessary to devise ways to improve the slipperiness by adding particles to the coating layer. Also, when the particle content is below the above upper limit value, the haze will not increase, and sufficient transparency of the film can be ensured.

[0028] The shape of the particles to be used is not particularly limited either, and any of spherical, massive, rod-shaped, flat-shaped, etc. can be used, and there are no particular restrictions on their hardness, specific gravity, color, etc. These series of particles may be used in combination of two or more types as necessary.

[0029] The method of adding particles into the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of manufacturing the polyester constituting each layer, but preferably after the completion of the esterification or transesterification reaction.

[0030] The polyester film may have a multilayer structure of two or more layers, but a three-layer polyester film is preferred. When having a three-layer structure, as described later, particles can be contained in the polyester layers (surface layers) on both surfaces, and it is not necessary to contain particles in the intermediate layer. Therefore, while enhancing slipperiness, antiblocking properties, etc., the transparency of the polyester film can also be enhanced. The polyester constituting each layer is as described above.

[0031] Further, when the polyester film has a multilayer structure of two or more layers, the average particle diameter of the particles used in the polyester layer (typically the polyester layer on the side where the release layer is not provided) on the surface opposite to the surface where the release layer is provided (anti-release surface) is preferably 1 to 6 μm, more preferably 2 to 5 μm, and particularly preferably 3 to 5 μm. Also, the content of the particles in the polyester layer is, for example, 0.03 to 1.0% by mass, preferably 0.3 to 1.0% by mass, more preferably 0.4 to 1.0% by mass, and particularly preferably 0.4 to 0.8% by mass. By simultaneously satisfying the average particle diameter and the addition amount, the anti-release surface has a larger maximum cross-sectional height (Rt) and has an appropriate uneven shape, and the release film can achieve both antiblocking prevention and releasability. Also, even when the polyester film is composed of a single layer, the single-layer polyester layer preferably contains particles from the viewpoints of antiblocking prevention and releasability, and the ranges of the average particle diameter and the particle addition amount are preferably as described above.

[0032] In the case of a two-layer or multi-layer polyester film, the polyester layer (surface layer) on the surface where the release layer is provided may or may not contain particles. However, from the viewpoint of slipperiness and the like, it is preferable to contain particles. The particle content (mass%) in the polyester layer (surface layer) on the surface where the release layer is provided is preferably less than the particle content (mass%) in the polyester layer on the surface opposite to the surface where the release layer is provided (anti-release surface). Specifically, the particle content (mass%) in the polyester layer on the surface where the release layer is provided is preferably in the range of 0.001 to 0.8 mass%, more preferably 0.01 to 0.5 mass%, and still more preferably 0.02 to 0.2 mass%.

[0033] In addition, in the polyester film of the present invention, in addition to the above-mentioned particles, conventionally known ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. can be added as necessary.

[0034] The thickness of the polyester film in the present invention is not particularly limited as long as it is within the range that can be formed into a film, but is preferably 10 to 300 μm, more preferably 15 to 200 μm, still more preferably 25 to 125 μm, and most preferably 38 to 75 μm.

[0035] <Method for producing a polyester film> Next, the production examples of the polyester film will be specifically described, but the present invention is not limited to the following production examples. For example, when producing a biaxially stretched polyester film, first, the polyester raw material described above is melt-extruded from a die using an extruder, and the molten sheet is cooled and solidified by a cooling roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to enhance the adhesion between the sheet and the rotating cooling drum, and the electrostatic printing adhesion method or the liquid coating adhesion method is preferably adopted. Next, the obtained unstretched sheet is stretched in one direction by 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. Subsequently, in the direction perpendicular to the first stretching direction, it is usually stretched at 70 to 170 °C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, a method of performing heat treatment at a temperature of 180 to 270 °C under tension or under relaxation within 30% to obtain a biaxially oriented film can be mentioned. In the above stretching, a method of performing the stretching in one direction in two or more stages can also be adopted. In that case, it is preferable to perform the stretching so that the final stretching ratios in the two directions are within the above ranges respectively.

[0036] In addition, a simultaneous biaxial stretching method can also be adopted for the production of the polyester film. The simultaneous biaxial stretching method is a method of simultaneously stretching and orienting the above-mentioned unstretched sheet in the machine direction and the width direction in a state where the temperature is controlled at usually 70 to 120 °C, preferably 80 to 110 °C. 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. Then, subsequently, heat treatment is performed at a temperature of 170 to 270 °C under tension or under relaxation within 30% to obtain a stretched and oriented film. Regarding the simultaneous biaxial stretching device adopting the above stretching method, a conventionally known stretching method such as a screw method, a pantograph method, or a linear drive method can be adopted.

[0037] <<Resin layer (A)>> Next, the formation of the resin layer (A) constituting the release film in the present invention will be described.

[0038] The resin layer (A) is a layer formed by curing a resin layer (A) composition having a curable silicone resin as the main component resin, and is disposed on at least one side of the above-described base film. It can also be said that the resin layer (A) is a release layer containing a cured product formed by curing the resin layer (A) composition.

[0039] The above-mentioned "main component resin" means the resin having the largest mass ratio among the resins constituting the present resin layer (A) composition, and is assumed to occupy 50% by mass or more, or 75% by mass or more, or 90% by mass or more, or 100% by mass of the resins constituting the present resin layer (A) composition.

[0040] The resin layer (A) in the present invention preferably contains a curable silicone resin.

[0041] As the curable silicone resin, a resin having a curable silicone resin as the main component may be used, or a modified silicone obtained by graft polymerization with an organic resin such as an acrylic resin, a urethane resin, an epoxy resin, or an alkyd resin may be used. Further, when the adhesive layer is a silicone adhesive or the like, it is preferable to contain a fluorosilicone resin or the like.

[0042] As the type of the curable silicone resin, any existing curing reaction type such as a thermosetting type such as an addition type or a condensation type, or an electron beam curing type such as an ultraviolet curing type can be used, and a plurality of types of curable silicone resins may be used in combination. Further, there is no particular limitation on the coating form of the curable silicone resin when forming the resin layer (A), and it may be in a form dissolved in an organic solvent, a solvent-free form, or an aqueous emulsion form.

[0043] The solvent-free curable silicone is a silicone having a viscosity that can be coated without dilution with a solvent, is composed of short polysiloxane chains, and is a relatively low molecular weight silicone resin. On the one hand, a solvent-based curable silicone is a silicone resin with a high viscosity that cannot be applied without being diluted with a solvent, and is a silicone having a relatively high molecular weight compared to a solvent-free curable silicone. From the viewpoints of good adhesion to the base film, a uniform coating appearance without coating unevenness, and easy adjustment of the thickness of the resin layer (A), a solvent-based curable silicone is preferred.

[0044] There is no limitation on the type of silicone resin used in the present invention, but from the viewpoint of excellent release properties such as light release properties, the use of a curable silicone resin containing an alkenyl group is preferred in the present invention. Examples of the curable silicone resin containing an alkenyl group as a diorganopolysiloxane include those represented by the following general formula (1). R (3-a) X a SiO-(RXSiO) m -(R2SiO) n -SiX a R (3-a) ···(1)

[0045] In general formula (1), R is a monovalent hydrocarbon group having 1 to 10 carbon atoms, and X is an organic group containing an alkenyl group. a is an integer of 0 to 3, preferably 1, m is 0 or more, but when a = 0, m is 2 or more. m and n are numbers satisfying 100 ≤ m + n ≤ 20000, and the above formula does not mean a block copolymer. R is a monovalent hydrocarbon group having 1 to 10 carbon atoms, specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, cycloalkyl groups such as cyclohexyl group, aryl groups such as phenyl group, tolyl group, etc. can be mentioned, and particularly methyl group and phenyl group are preferred. X is an organic group containing an alkenyl group, preferably having 2 to 10 carbon atoms. Specifically, vinyl group, allyl group, hexenyl group, octenyl group, acryloylpropyl group, acryloylmethyl group, methacryloylpropyl group, cyclohexenylethyl group, vinyloxypropyl group, etc. can be mentioned, and particularly vinyl group, hexenyl group, etc. are preferred. Specifically exemplified are dimethylsiloxane·methylhexenylsiloxane copolymer blocked with trimethylsiloxy groups at both ends of the molecular chain (96 mol% of dimethylsiloxane units, 4 mol% of methylhexenylsiloxane units), dimethylsiloxane·methylhexenylsiloxane copolymer blocked with dimethylvinylsiloxy groups at both ends of the molecular chain (97 mol% of dimethylsiloxane units, 3 mol% of methylhexenylsiloxane units), dimethylsiloxane·methylhexenylsiloxane copolymer blocked with dimethylhexenylsiloxy groups at both ends of the molecular chain (95 mol% of dimethylsiloxane units, 5 mol% of methylhexenylsiloxane units).

[0046] Next, as the polyorganosiloxane containing SiH groups, which is necessary to react with a curable silicone resin containing an alkenyl group to form a stronger silicone release layer, an organohydropolysiloxane having at least 2 hydrogen atoms, preferably 3 or more hydrogen atoms, bonded to silicon atoms in one molecule can be used. Linear, branched, cyclic ones, etc. can be used, and compounds represented by the following general formula (2) can be mentioned, but are not limited to these. HbR 1 (3-b) SiO-(HR1 SiO) x -(R 1 2SiO) y -SiR 1 (3-b) H b ···(2)

[0047] In general formula (2), R 1 is a monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond having 1 to 6 carbon atoms. b is an integer from 0 to 3, and x and y are each integers. Specifically, examples include molecular chain both-end trimethylsiloxy group-blocked methylhydrogen polysiloxane, molecular chain both-end trimethylsiloxy group-blocked dimethylsiloxane·methylhydrogen siloxane copolymer, molecular chain both-end dimethylhydrogen siloxy group-blocked methylhydrogen polysiloxane, and molecular chain both-end dimethylhydrogen siloxy group-blocked dimethylsiloxane·methylhydrogen siloxane copolymer.

[0048] Next, specific examples of various commercially available types of silicone resins that can be used in the present invention are listed. As products of Shin-Etsu Chemical Co., Ltd., there are KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X-62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62-7213, X-41-3035. As products of Momentive Performance Materials, there are YSR-3022, TPR-6700, TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605. As products of Toray Dow Corning Co., Ltd., there are SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, LTC303E, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210. Among the DEHESIVE series products of Asahi Kasei Wacker Silicone Co., Ltd., DEHESIVE 636, 919, 920, 921, 924, 929, etc. are exemplified, but are not limited thereto.

[0049] It is preferable to use a platinum-based catalyst that promotes an addition reaction for the resin layer (A). Examples of this component include platinum-based compounds such as chloroplatinic acid, an alcohol solution of chloroplatinic acid, a complex of chloroplatinic acid and an olefin, a complex of chloroplatinic acid and an alkenylsiloxane, platinum black, platinum-supported silica, and platinum-supported activated carbon.

[0050] The content of the curing catalyst in the resin layer (A) is preferably 0.5 to 500 mass ppm in terms of the amount in terms of metal, more preferably 5 mass ppm or more, still more preferably 10 mass ppm or more, and more preferably 300 mass ppm or less, and even more preferably 200 mass ppm or less, based on the curable silicone resin. When the content of the platinum-based catalyst in the release layer is at least the above lower limit value, sufficient release force can be obtained, the curing reaction proceeds sufficiently, and problems such as deterioration of the coated surface do not occur. On the other hand, when the content of the platinum-based catalyst in the resin layer (A) is at most the above upper limit value, in addition to being advantageous in terms of cost, problems in the process such as increased reactivity and generation of gel foreign matter do not occur.

[0051] Also, since the addition-type reaction is very reactive, in some cases, acetylene alcohol may be added as a reaction inhibitor. The component is an organic compound having a carbon-carbon triple bond and a hydroxyl group, and is preferably a compound selected from the group consisting of 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and phenylbutynol.

[0052] The content of the reaction controller is preferably 0.001 to 5.0 parts by mass, more preferably 0.01 to 2.0 parts by mass, still more preferably 0.05 to 1.5 parts by mass, and most preferably 0.1 to 0.5 parts by mass, per 100 parts by mass of the total amount of the resin layer (A) composition (on a non-volatile component basis). By setting it within the above range, the curable silicone resin is not inhibited from curing, and the light releasability of the release film can be ensured without reducing the reaction activity.

[0053] In the resin layer (A) constituting the release film, a catalyst can be used in combination for the purpose of promoting hydrolysis and condensation reactions. Specific examples of the catalyst include organic acids such as acetic acid, butyric acid, maleic acid, and citric acid; inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid; basic compounds such as triethylamine; organometallic salts such as tetrabutyl titanate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dioleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis(triethoxysiloxy)tin, and dibutyltin benzyl maleate; and fluorine element-containing compounds such as KF and NH4F. The above catalysts may be used alone or in combination of two or more. Among them, organometallic salts are particularly preferable in terms of good coating film durability.

[0054] In order to adjust the releasability and the like of the resin layer (A), various release control agents may be used in combination. When making the peel force into a double release force, generally, an organopolysiloxane resin, silica particles, silicone species with a double release force, etc. are adjusted to an appropriate content in the resin layer (A) to obtain a desired peel force.

[0055] Specific examples of commercially available double release agents include KS-3800, X-92-183 manufactured by Shin-Etsu Chemical Co., Ltd., SD7292, BY24-843, BY24-4980 manufactured by Toray Dow Corning Co., Ltd.

[0056] When making the peel force into a light release force, various low molecular weight siloxanes are selected and adjusted to an appropriate content in the resin layer (A) so that the siloxane transfer component exhibits release performance. Examples of the low molecular weight siloxane compound include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, etc. In addition, as other compounds of these low molecular weight cyclic siloxanes, there are dimethylsiloxane oligomers blocked with trimethylsiloxy groups at both ends of the molecular chain; dimethylsiloxane oligomers blocked with dimethylhydroxysiloxy groups at both ends of the molecular chain, etc. These compounds may be mixed and used as necessary.

[0057] As described above, the resin layer (A) composition may contain a light release agent as necessary, and a silicone oil having a dimethylsiloxane skeleton (DM) represented by the following formula (3) and a methylphenylsiloxane skeleton (MP) represented by the following formula (4) is preferred. Since the light release agent has a dimethylsiloxane skeleton (DM) and a methylphenylsiloxane skeleton (MP), even if it migrates to the adhesive layer to be laminated, it can penetrate into the adhesive layer, and a decrease in adhesive strength can be reduced. The ratio (DM:MP) of the dimethylsiloxane skeleton (DM) represented by the following formula (3) and the methylphenylsiloxane skeleton (MP) represented by the following formula (4) is preferably in the range of 98:2 to 70:30 in molar ratio, more preferably in the range of 95:5 to 80:20, and particularly preferably in the range of 92:8 to 85:15. By setting DM:PM within the above range, the releasability of this release film can be ensured. Also, the mass average molecular weight of the light release agent is preferably less than 10,000. When the mass average molecular weight of the light release agent is less than 10,000, it is advantageous in terms of migration property and light releasability.

[0058]

Chemical formula

[0059]

Chemical formula

[0060] These low molecular weight siloxane compounds can achieve the desired light release by containing 0.1 to 15.0% by mass, preferably 0.5 to 10.0% by mass, and more preferably 0.5 to 5.0% by mass in the silicone resin as a migration component. When it is 0.1% by mass or more, the migration component is sufficient, so the release property is sufficiently exhibited. When the content of the low molecular weight siloxane is 15.0% by mass or less, the migration component does not precipitate excessively, and there is no concern about process contamination.

[0061] The resin layer (A) composition can contain a diluent solvent as needed. Examples of the diluent solvent include aromatic hydrocarbons such as toluene, aliphatic hydrocarbons such as hexane, heptane, and isooctane, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone (MEK) and isobutyl methyl ketone, alcohols such as ethanol and 2-propanol, and ethers such as diisopropyl ether and dibutyl ether. These are preferably used alone or in combination considering solubility, coatability, boiling point, etc.

[0062] In addition, it is preferable to use in combination an organosilicon compound represented by the following general formula (5) in the resin layer (A) to improve the coating film adhesion to the film. Si(X) d (Y) e (R 1 ) f ···(5) [In the above formula, X is an organic group having at least one selected from an epoxy group, a mercapto group, a (meth)acryloyl group, an alkenyl group, a haloalkyl group, and an amino group, R 1 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, Y is a hydrolyzable group, d is an integer of 1 or 2, e is an integer of 2 or 3, f is an integer of 0 or 1, and d + e + f = 4]

[0063] As the organosilicon compound represented by the general formula (5), those having two hydrolyzable groups Y (D unit source) or three hydrolyzable groups Y (T unit source) that can form a siloxane bond by a hydrolysis-condensation reaction can be used.

[0064] In the general formula (5), the monovalent hydrocarbon group R 1 has 1 to 10 carbon atoms, and particularly a methyl group, an ethyl group, and a propyl group are preferable.

[0065] In the general formula (5), examples of the hydrolyzable group Y include the following. That is, a methoxy group, an ethoxy group, a butoxy group, an isopropenoxy group, an acetoxy group, a butanoxime group, an amino group, and the like. These hydrolyzable groups may be used alone or in combination of two or more. When a methoxy group or an ethoxy group is applied, good storage stability can be imparted to the coating material, and since it has appropriate hydrolyzability, it is particularly preferable.

[0066] Specific examples of the organosilicon compound contained in the resin layer (A) include vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 5-hexenyltrimethoxysilane, p-styryltrimethoxysilane, trifluoropropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiisopropenoxysilane, and the like.

[0067] The resin layer (A) preferably contains substantially no particles. By substantially not containing particles in the resin layer (A), the peelability can be stabilized while reducing the transferability. Note that "substantially not containing" means that the resin layer (A) may contain particles in a small amount as long as the effects of the present invention are not inhibited. For example, particles that are unavoidably mixed in may be included. The specific content of particles in the present resin layer (A) (A layer) is, based on the non-volatile component, for example, less than 0.05% by mass, preferably less than 0.01% by mass, more preferably less than 0.0001% by mass. The range of the content of particles in the composition of the present resin layer (A) based on the non-volatile component is also the same as the above content of particles.

[0068] Furthermore, within a range not impairing the gist of the present invention, the resin layer (A) composition may contain, if necessary, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, a conductive agent, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, a pigment, and the like.

[0069] The number average molecular weight (Mn) of the curable silicone resin is preferably 9,000 or more and 350,000 or less. When the number average molecular weight (Mn) of the curable silicone resin is set to the above lower limit value or more, when an adhesive layer is laminated on the release film, the amount of the low molecular weight silicone resin eluting or migrating into the adhesive layer can be reduced, and also, by thickly coating the resin layer (A), it becomes easier to obtain a light peeling effect. On the other hand, when the number average molecular weight (Mn) of the curable silicone resin is set to the above upper limit value or less, it is possible to prevent the viscosity from increasing and the fluidity of the resin layer (A) composition from decreasing. Therefore, when the resin layer (A) composition is applied, it is possible to prevent the occurrence of streak-like coating unevenness and to easily smooth the surface of the resin layer (A). From such a viewpoint, the number average molecular weight (Mn) of the curable silicone resin is preferably 9,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, and particularly preferably 30,000 or more. On the other hand, it is preferably 350,000 or less, more preferably 50,000 or less, and even more preferably 40,000 or less.

[0070] From the same viewpoint as the number average molecular weight, the mass average molecular weight (Mw) of the curable silicone resin is preferably 10,000 to 500,000, more preferably 20,000 or more, even more preferably 50,000 or more, particularly preferably 80,000 or more, and more preferably 250,000 or less, and even more preferably 100,000 or less.

[0071] For the curable silicone resin, the ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) is preferably 1.7 to 3.5, more preferably 1.9 to 3.0, and even more preferably 2.0 to 3.0. By satisfying this range, it is expected that the crosslinking reaction can proceed efficiently. Note that the number-average molecular weight (Mn) and the weight-average molecular weight (Mw) are values determined by gel permeation chromatography (GPC) measurement based on polystyrene standards. The specific measurement method is to measure the chromatogram using a GPC measurement device and determine the number-average molecular weight (Mn) and the weight-average molecular weight (Mw) based on the calibration curve using standard polystyrene. Specifically, 4 mg of the sample for measurement was dissolved in 4 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into the GPC measurement device for measurement. Tetrahydrofuran (THF) was used as the eluent. For the analysis, "Ecosec8320" manufactured by Tosoh Corporation was used, and for the guard column, "TSKgel guardcolumn HXL-L" manufactured by Tosoh Corporation and for the column, four "TSKgel GMHXL" manufactured by Tosoh Corporation were connected in series and used. Also, the analysis was performed under the conditions of an oven temperature of 40 °C and a THF flow rate of 1.0 mL / min, and RI was used for detection.

[0072] The curable silicone resin may be composed of a combination of two or more curable silicone resins. In that case, it is preferable that the average of the number-average molecular weight (Mn) and the weight-average molecular weight (Mw) of the two or more curable silicone resins is within the above range. Here, the average referred to is the weighted average weighted by the mass of each resin. Also, when using a main agent and a silicone crosslinking agent as the curable silicone resin, it is preferable that the weight-average molecular weight (Mn), the number-average molecular weight (Mw), and Mw / Mn of the main agent are within the above range.

[0073] The viscosity of the curable silicone resin at 25 °C when adjusted to 15% by mass with n-heptane solvent dilution is preferably 1 to 400 m cps, more preferably 5 to 300 m cps, and even more preferably 10 to 200 m cps. If the viscosity of the curable silicone resin is 1 m cps or more, the appropriate viscosity of the coating liquid suppresses repellency, and a uniform coating appearance with high visibility can be obtained, which is preferable. If it is 400 m cps or less, the fluidity of the resin layer (A) composition can be maintained, and when the resin layer (A) composition is applied, the occurrence of streak-like coating unevenness can be suppressed, and the surface of the resin layer (A) can be smoothed. The viscosity was measured by diluting the curable silicone resin with n - heptane to 15% by mass as a solvent, and measuring the viscosity of this solution at 25 °C using an E - type viscometer ("TVE - 22L" manufactured by Toki Sangyo Co., Ltd.).

[0074] When the curable silicone resin has an alkenyl group in the silicone resin, the content of the alkenyl group is preferably 0.4 to 2.5 mol%, more preferably 0.5 to 2.0 mol%, still more preferably 0.5 to 1.5 mol% with respect to the total amount of siloxane components. By satisfying this range, since a certain amount or more of the alkenyl group is contained, the release layer is sufficiently cured. On the other hand, since the amount of the alkenyl group does not become excessive, it is possible to prevent the peeling force from becoming heavy after air exposure.

[0075] When the curable silicone resin has an Si - H group in the silicone resin, the content of the Si - H group is preferably 0.8 to 2.5 mol%, more preferably 0.8 to 2.0 mol%, still more preferably 1.0 to 2.0 mol% with respect to the total amount of siloxane components. By satisfying this range, since a certain amount or more of the Si - H group is contained, the release layer is sufficiently cured. On the other hand, since the amount of the Si - H group does not become excessive, it is possible to prevent reaction with the adhesive layer, and re - peeling of the release film can be suppressed.

[0076] The curable silicone resin may contain an alkenyl group and an Si - H group (also simply referred to as "H group") in the side chain and / or at the terminal of the main chain composed of siloxane bonds in the same structure. In that case, it is preferable that the contents of the alkenyl group and the Si - H group are within the above ranges.

[0077] The content of the total siloxane components in this release layer composition is, for example, 1It can be measured from the integration ratio of the dimethylsiloxane unit in the main chain and other units by 1H-NMR. Also, the content of vinyl groups and Si-H groups indicates the ratio with respect to the total amount of functional groups bonded to the siloxane chain, 1 and can be evaluated by measuring 1H-NMR. However, it is not limited to such a method.

[0078] From the viewpoints of ultra-light peeling, prevention of blocking, and suppression of the increase in migration property, the thickness of the resin layer (A) is preferably in the range of 0.2 to 2.0 μm, more preferably 0.4 to 1.5 μm, still more preferably 0.4 to 1.2 μm, and most preferably 0.4 to 1.0 μm. When the thickness of the resin layer (A) is less than 0.2 μm, as will be described later, even if the elastic modulus of the resin layer (A) is within a predetermined range, it is difficult to lightly peel the resin layer (A). Also, when the thickness is more than 2.0 μm, there may be a case where the migration property of the resin layer (A) component to a pressure-sensitive adhesive tape or the like increases, or blocking may not be sufficiently prevented.

[0079] The elastic modulus of the resin layer (A) at 25°C is preferably 500 MPa or less, more preferably 65 to 400 MPa, and still more preferably 80 to 300 MPa. By satisfying these ranges, good peelability can be exhibited with respect to the pressure-sensitive adhesive layer. Note that the elastic modulus of the resin layer (A) can be adjusted by the type of silicone resin used, the thickness of the resin layer (A), etc. For example, when the resin layer (A) becomes thinner, the elastic modulus tends to increase. Also, the elastic modulus referred to here is a value measured by a nanoindenter.

[0080] The normal peel force of the resin layer (A) is preferably 5 g / 25 mm or less, more preferably 0.1 to 4 g / 25 mm, and still more preferably 0.5 to 3 g / 25 mm. When the normal peel force is 5 g / 25 mm or less, good peelability can be exhibited even with respect to a pressure-sensitive adhesive layer with a low elastic modulus due to the increase in size and thinning of the optical member. On the other hand, when the normal peel force exceeds 5 g / 25 mm, it may be difficult to peel when peeling from the pressure-sensitive adhesive layer, and there may be a case where the pressure-sensitive adhesive layer is transferred to the release film side due to deformation or breakage of the pressure-sensitive adhesive layer.

[0081] The residual adhesion rate of the resin layer (A) serves as an indicator of the migration property of the migration components derived from the resin layer (A) migrating to an adhesive tape or the like for lamination. In the resin layer (A) with a large migration property, a large number of migration components adhere to the stacked evaluation film. Therefore, the peel strength of the adhesive tape laminated to the evaluation film becomes small, and the residual adhesion rate (%) also decreases. Therefore, it is preferable that the residual adhesion rate (%) is high, preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. If the residual adhesion rate is 80% or more, it can be considered that there are no problems in actual use.

[0082] The rate of re-peeling after pressing of the resin layer (A) is preferably 100% or less, more preferably 50% or less, and even more preferably 20% or less. If the rate of re-peeling after pressing is 100% or less, when the present release film is wound into a roll, the re-peeling of the resin layer (A) at the lower winding part of the roll where pressure is applied by the film is suppressed to a small extent, and no problem due to re-peeling occurs. The calculation method of the rate of re-peeling after pressing is as described in the examples.

[0083] Regarding the formation of the resin layer (A), it may be provided by in-line coating that treats the film surface during the film forming process of the film, or off-line coating that is applied outside the system on a once-produced film may be employed. However, it is more preferably formed by off-line coating.

[0084] As a method for providing the resin layer (A) on the film, conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, and curtain coating can be used.

[0085] The film constituting the release film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

[0086] The curing conditions for forming the resin layer (A) are not particularly limited. When the resin layer (A) is provided by offline coating, usually, the heat treatment is preferably carried out with a temperature of 80°C or higher for 10 seconds or more, more preferably at 100 - 200°C for 3 - 40 seconds, still more preferably at 120 - 190°C for 3 - 40 seconds, and even more preferably at 150 - 180°C for 3 - 40 seconds as a guide.

[0087] Also, if necessary, heat treatment and irradiation with active energy rays such as ultraviolet irradiation may be used in combination. As an energy source for curing by irradiation with active energy rays, known devices and energy sources can be used. For example, as a light source, a fusion (H) lamp, a metal halide lamp, a high-pressure mercury lamp (ozone generation type, ozone-free type), a UV-LED, etc. are exemplified.

[0088] The irradiation with active energy rays is not particularly limited, but in the case of ultraviolet irradiation, in terms of the integrated light quantity conversion, it is 10 - 3000 mJ / cm 2 , preferably 50 - 2000 mJ / cm 2 , still more preferably 100 - 1000 mJ / cm 2 is in the range. By setting the integrated light quantity conversion of ultraviolet irradiation within the above range, the curing of the resin layer (A) is promoted, and on the other hand, by not irradiating excessively, it is possible to prevent the resin layer (A) from being destroyed and the peeling force after irradiation from becoming excessive.

[0089] In the release film of the present invention, it is preferable that the surface resistivity of at least one surface of the resin layer (A) or the resin layer (B) is 1×10 12 Ω / □ or less. The lower the surface resistivity of the resin layer (A) or the resin layer (B), the better the antistatic property, and it is possible to suppress the charging of the film in the process and prevent the adhesion of foreign substances and the like.

[0090] The center line average roughness (Ra(A)) of the surface of the resin layer (A) is preferably 30 nm or less. When the center line average roughness (Ra(A)) is 30 nm or less, ultra-light peeling becomes possible, which is preferable. Regarding (Ra(A)), it is more preferably 25 nm or less, and particularly preferably 20 nm or less. On the other hand, regarding the lower limit value, from the viewpoint of film handling properties, 5 nm or more is preferable.

[0091] <<Resin layer (B)>> Regarding the resin layer (B) in the present invention, it will be described below.

[0092] The resin layer (B) constituting the release film in the present invention may be provided on the surface opposite to the surface provided with the resin layer (A) of the base film, and may be a resin layer (B) containing a non-silicone-based release agent. More preferably, it is a resin layer (B) containing a non-silicone-based release agent and having antistatic performance.

[0093] The non-silicone-based release agent used for the resin layer (B) is not particularly limited as long as it is a release agent excluding silicone compounds, and a conventionally known release agent can be used. For example, long-chain alkyl group-containing compounds, fluorine compounds, waxes, etc. can be mentioned. Among these, long-chain alkyl compounds and waxes are preferable from the viewpoints of less contamination and excellent blocking reduction. Particularly from the viewpoint of blocking reduction, long-chain alkyl compounds are more preferable. These release agents may be used alone or in combination of multiple types.

[0094] A silicone compound is a compound having a siloxane bond in the molecule, and includes those having various functional groups on the side chains and / or terminals of the main chain composed of siloxane bonds. For example, an ether group, a hydroxyl group, an amino group, an epoxy group, a carboxylic acid group, a halogen group such as fluorine, a perfluoroalkyl group, a hydrocarbon group (alkyl group, alkenyl group, aryl group, various aromatic groups, etc.) and the like can be mentioned. When the resin layer (B) contains a silicone compound, it strongly blocks with the resin layer (A), and the surface of the resin layer (A) is deformed or the like, so that the peeling property of the resin layer (A) deteriorates. Therefore, it is difficult to use in this release film.

[0095] A long-chain alkyl group-containing compound is a compound having a linear or branched alkyl group usually having 6 or more carbon atoms, preferably 8 or more carbon atoms, and more preferably 12 or more carbon atoms. Examples of the alkyl group include a hexyl group, an octyl group, a decyl group, a lauryl group, an octadecyl group, a behenyl group and the like. Examples of the compound having an alkyl group include various long-chain alkyl group-containing polymer compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing ether compounds, long-chain alkyl group-containing quaternary ammonium salts and the like. Considering heat resistance and contamination, it is preferably a polymer compound. Further, from the viewpoint of effectively obtaining releasability, it is more preferably a polymer compound having a long-chain alkyl group in the side chain.

[0096] A polymer compound having a long-chain alkyl group in the side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive group include a hydroxyl group, an amino group, a carboxyl group, an acid anhydride and the like. Examples of the compound having these reactive groups include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, a reactive group-containing polyester resin, a reactive group-containing poly(meth)acrylic resin and the like. Among these, polyvinyl alcohol is preferably used in consideration of releasability and ease of handling.

[0097] Examples of the compound having an alkyl group capable of reacting with the above reactive group include long-chain alkyl group-containing isocyanates such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, behenyl isocyanate, long-chain alkyl group-containing acid chlorides such as hexyl chloride, octyl chloride, decyl chloride, lauryl chloride, octadecyl chloride, behenyl chloride, long-chain alkyl group-containing amines, long-chain alkyl group-containing alcohols, and the like. Among these, considering releasability and ease of handling, long-chain alkyl group-containing isocyanates are preferred, and octadecyl isocyanate is particularly preferred.

[0098] In addition, a polymer compound having a long-chain alkyl group in the side chain can also be obtained by polymerization of long-chain alkyl (meth)acrylate or copolymerization of long-chain alkyl (meth)acrylate and other vinyl group-containing monomers. Examples of the long-chain alkyl (meth)acrylate include hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, behenyl (meth)acrylate, and the like.

[0099] The wax is a wax selected from natural waxes, synthetic waxes, and waxes blended therefrom. Natural waxes include plant waxes, animal waxes, mineral waxes, and petroleum waxes. Examples of plant waxes include candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, etc. Examples of animal waxes include beeswax, lanolin, whale wax, etc. Examples of mineral waxes include montan wax, ozokerite, ceresin, etc. Examples of petroleum waxes include paraffin wax, microcrystalline wax, petrolatum, etc. Examples of synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, ketones, etc. Examples of synthetic hydrocarbons include, for example, Fischer-Tropsch wax (also known as Sasol wax), polyethylene wax, and other polymers that are low molecular weight polymers (specifically, polymers with a viscosity-average molecular weight of 500 to 20,000), namely, polypropylene, ethylene-acrylic acid copolymer, polyethylene glycol, polypropylene glycol, block or graft conjugates of polyethylene glycol and polypropylene glycol, etc. Examples of modified waxes include montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives, etc. The derivatives here are compounds obtained by any one of the treatments of purification, oxidation, esterification, saponification, or a combination thereof. Examples of hydrogenated waxes include hydrogenated castor oil and hydrogenated castor oil derivatives.

[0100] Among the above waxes, from the viewpoint of stable properties, synthetic waxes are preferred, among which polyethylene wax is more preferred, and oxidized polyethylene wax is even more preferred. The number average molecular weight (Mn) of the synthetic wax is preferably in the range of 500 to 30,000, more preferably 1000 to 15,000, and even more preferably 2000 to 8000, from the viewpoints of stability of properties such as blocking and handleability.

[0101] A fluorine compound is a compound containing fluorine atoms in the compound. From the viewpoint of the coating appearance by in-line coating, an organic fluorine compound is preferably used. For example, a perfluoroalkyl group-containing compound, a polymer of an olefin compound containing fluorine atoms, an aromatic fluorine compound such as fluorobenzene, etc. can be mentioned. From the viewpoint of releasability, it is preferably a compound having a perfluoroalkyl group. Furthermore, a compound containing a long-chain alkyl compound as described later can also be used as the fluorine compound.

[0102] A compound having a perfluoroalkyl group is, for example, a perfluoroalkyl (meth)acrylate, a perfluoroalkylmethyl (meth)acrylate, a 2-perfluoroalkylethyl (meth)acrylate, a 3-perfluoroalkylpropyl (meth)acrylate, a 3-perfluoroalkyl-1-methylpropyl (meth)acrylate, a 3-perfluoroalkyl-2-propenyl (meth)acrylate, etc. perfluoroalkyl group-containing (meth)acrylate and its polymer, a perfluoroalkylmethyl vinyl ether, a 2-perfluoroalkylethyl vinyl ether, a 3-perfluoropropyl vinyl ether, a 3-perfluoroalkyl-1-methylpropyl vinyl ether, a 3-perfluoroalkyl-2-propenyl vinyl ether, etc. perfluoroalkyl group-containing vinyl ether and its polymer, etc. can be mentioned. Considering heat resistance and contamination, it is preferably a polymer. The polymer may be a single compound or a polymer of a plurality of compounds. Also, from the viewpoint of releasability, the perfluoroalkyl group preferably has 3 to 11 carbon atoms. Furthermore, it may be a polymer with a compound containing a long-chain alkyl compound as described later. Also, from the viewpoint of adhesion to the substrate, it is also preferably a polymer with vinyl chloride.

[0103] For the formation of the resin layer (B), from the viewpoint of preventing adhesion of foreign substances and the like, it is preferably contained an antistatic agent. For example, a polymer doped with another anionic compound in a compound composed of thiophene or a thiophene derivative, or a polymer self-doped with an anionic group in a compound composed of thiophene or a thiophene derivative, or a polymer containing a monomer having an alkylsulfonic acid ion as a counter ion as a component can be used. Among them, from the viewpoint of obtaining excellent antistatic performance, it is more preferable to contain a compound composed of thiophene or a thiophene derivative.

[0104] Examples of the compound composed of thiophene or a thiophene derivative, and examples of the polymer doped with another anionic compound in a compound composed of thiophene or a thiophene derivative, or the polymer self-doped with an anionic group in a compound composed of thiophene or a thiophene derivative include those obtained by polymerizing a compound of the following formula (6) or the following formula (7) in the presence of a polyanion.

[0105]

Chemical formula

[0106] In the above formula (6), R 1 and R 2 each independently represent a hydrogen atom or an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, etc. having 1 to 20 carbon atoms.

[0107]

Chemical formula

[0108] In the above formula (7), n represents an integer of 1 to 4.

[0109] Examples of the polyanion used during coincidence include, for example, poly(meth)acrylic acid, polymaleic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, and the like. As a method for producing such a polymer, for example, a method as disclosed in JP-A-7-90060 can be adopted.

[0110] In the present invention, in the compound of the above formula (7), n is 2, and a compound using polystyrene sulfonic acid as the polyanion is preferably used.

[0111] When these polyanions are acidic, part or all of them may be neutralized. As the base used for neutralization, ammonia, organic amines, and alkali metal hydroxides are preferable.

[0112] Specific examples of the polymer containing a monomer having an alkyl sulfonate ion as a counter ion as a component include, for example, a polymer having a constituent element represented by the following formula (8) as a repeating unit. These homopolymers, copolymers, and further, a plurality of other components may be copolymerized. From the viewpoint of improving the antistatic property, a homopolymer is preferably used.

[0113]

Chemical formula

[0114] As the structure of the polymer, for example, in the above formula, the substituent R 1 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 2 is -O- or -NH-, R 3 is an alkylene group having 1 to 6 carbon atoms or another structure capable of forming the structure of formula (8), R 4 , R 5 , R 6 at least one of them is a hydrogen atom, and the other substituents are alkyl groups having 1 to 3 carbon atoms, or hydroxyalkyl groups having 2 to 3 carbon atoms in the alkyl group, X - is an alkyl sulfonate ion having an alkyl group having 1 to 4 carbon atoms.

[0115] For the formation of the resin layer (B), it is preferable to contain a polyhydroxy compound for the purpose of improving the coating appearance and antistatic performance. As the polyhydroxy compound, it is preferable to use one or more compounds selected from polyglycerin and alkylene oxide adducts to polyglycerin or derivatives thereof. Polyglycerin is a compound represented by the following general formula (9).

[0116]

Chemical formula

[0117] In the above formula (9), n is 2 or more, and in the present invention, n in the formula is usually in the range of 2 to 20, preferably 3 to 15, more preferably 3 to 12.

[0118] The alkylene oxide adduct to polyglycerin has a structure in which an alkylene oxide is addition-polymerized to the hydroxyl group of polyglycerin represented by the above general formula (9).

[0119] Here, the structure of the alkylene oxide added to each hydroxyl group of the polyglycerin skeleton may be different. Also, it is sufficient that it is added to at least one hydroxyl group in the molecule, and it is not necessary that alkylene oxide or its derivative is added to all hydroxyl groups.

[0120] Preferred alkylene oxides added to polyglycerin are ethylene oxide or propylene oxide. If the alkylene chain of the alkylene oxide becomes too long, the hydrophobicity becomes strong, the dispersibility in the coating solution deteriorates, and the antistatic property and transparency of the resin layer (B) tend to deteriorate. Particularly preferred is ethylene oxide. Also, the number of added moles is preferably in the range of 200 to 2000 in terms of the number average molecular weight (Mn) of the final compound, more preferably in the range of 300 to 1000, and even more preferably in the range of 400 to 900.

[0121] The above polyglycerin or alkylene oxide adduct to polyglycerin may be used alone or in combination of two or more kinds.

[0122] For the formation of the resin layer (B), various conventionally known polymers can be used in combination as a binder component from the viewpoints of improving coating appearance and transparency. Specific examples of the polymer include polyester resin, urethane resin, acrylic resin, polyvinyl alcohol, vinyl chloride-vinyl acetate copolymer, and the like. From the viewpoint of strengthening the resin layer (B) and reducing blocking, it is preferable to use a polyester resin or a urethane resin.

[0123] Examples of the polyester resin include those composed of the following polycarboxylic acids and polyhydroxy compounds as main components. That is, examples of the polycarboxylic acids 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, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, 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, monopotassium trimellitate, and their ester-forming derivatives. Examples of the polyhydroxy compounds include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylol ethyl sulfonate, potassium dimethylolpropionate, and the like. The polyester resin is a polycondensate of a polycarboxylic acid and a polyhydroxy compound. One or more of the polycarboxylic acids and polyhydroxy compounds may be appropriately selected from the above-mentioned compounds, and the polyester resin may be synthesized by a conventional polycondensation reaction. Further, the polyester resin may be in the form of an aqueous dispersion, and in that case, a hydrophilic functional group or the like may be appropriately introduced into the polyester resin.

[0124] A urethane resin is a polymer compound having a urethane bond in the molecule. Usually, a urethane resin is prepared by the reaction of a polyol and an isocyanate. Examples of polyols include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination of multiple types. The urethane resin may be an aqueous dispersion, and in that case, for example, a hydrophilic functional group may be appropriately introduced into the polyol.

[0125] Polycarbonate polyols are obtained by a dealcoholization reaction from polyhydric alcohols and carbonate compounds. Examples of polyhydric alcohols include ethylene glycol, 1,2 - propylene glycol, 1,3 - propylene glycol, 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, 3,3 - dimethylolheptane, etc. Examples of carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, etc. Examples of polycarbonate - based polyols obtained from these reactions include poly(1,6 - hexylene) carbonate, poly(3 - methyl - 1,5 - pentylene) carbonate, etc.

[0126] Examples of polyester polyols include those obtained from the reaction of polycarboxylic acids (such as 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 with polyhydric alcohols (such as 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 - 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, lactone diol, etc.).

[0127] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene - propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, etc.

[0128] Among the above polyols, polycarbonate polyols and polyester polyols are more preferably used to improve the adhesion to various functional layers.

[0129] Examples of the polyisocyanate compound used to obtain 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, dicyclohexylmethane diisocyanate, and isopropylidene dicyclohexyl diisocyanate. These may be used alone or in combination of two or more.

[0130] 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. Generally, a chain extender having two hydroxyl groups or amino groups can be mainly used.

[0131] Examples of the chain extender having two carboxyl groups include glycols such as aliphatic glycols like ethylene glycol, propylene glycol, and butanediol, aromatic glycols like xylylene glycol and bis(hydroxyethoxy)benzene, and ester glycols like neopentyl glycol hydroxypivalate. Examples of the chain extender having two amino groups include aromatic diamines such as tolylene diamine, xylylene diamine, and diphenylmethane diamine, aliphatic diamines such as ethylene diamine, propylene diamine, hexane diamine, 2,2-dimethyl-1,3-propane diamine, 2-methyl-1,5-pentane diamine, trimethylhexane diamine, 2-butyl-2-ethyl-1,5-pentane diamine, 1,8-octane diamine, 1,9-nonane diamine, and 1,10-decane diamine, and alicyclic diamines such as 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethane diamine, isopropylidene cyclohexyl-4,4'-diamine, 1,4-diaminocyclohexane, and 1,3-bis(aminomethyl)cyclohexane.

[0132] The urethane resin in the present invention may be in a solvent medium, preferably in an aqueous medium. To disperse or dissolve the urethane resin in water, there are a forced emulsification type using an emulsifier, a self-emulsification type or a water-soluble type in which a hydrophilic group is introduced into the urethane resin. In particular, a self-emulsification type in which an ionic group is introduced into the structure of the urethane resin to form an ionomer is preferable because of its excellent storage stability of the liquid, water resistance, transparency, and adhesion of the resulting coating layer.

[0133] Examples of the ionic group to be introduced include various ones such as carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, and quaternary ammonium salt, among which the carboxyl group is preferred. As a method for introducing a carboxyl group into a urethane resin, various methods can be adopted at each stage of the polymerization reaction. For example, there are a method of using a resin having a carboxyl group as a copolymerization component during prepolymer synthesis, and a method of using a component having a carboxyl group as one component such as a polyol, a polyisocyanate, or a chain extender. In particular, a method of introducing a desired amount of carboxyl group according to the charged amount of this component by using a carboxyl group-containing diol is preferred. For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis-(2-hydroxyethyl)propionic acid, bis-(2-hydroxyethyl)butanoic acid, etc. can be copolymerized with the diol used in the polymerization of the urethane resin. Further, it is preferable that this carboxyl group be in the form of a salt neutralized with ammonia, an amine, an alkali metal, an inorganic alkali, etc. Particularly preferred are ammonia, trimethylamine, and triethylamine. Such a polyurethane resin can use the carboxyl group from which the neutralizing agent has removed in the drying process after coating as a crosslinking reaction point by another crosslinking agent. Thereby, not only the stability in the state of the liquid before coating is excellent, but also the durability, solvent resistance, water resistance, blocking resistance, etc. of the obtained coating layer can be further improved.

[0134] An acrylic resin is a polymer composed of polymerizable monomers including acrylic and methacrylic monomers. These may be homopolymers, copolymers, or copolymers with polymerizable monomers other than acrylic and methacrylic monomers. Also included are copolymers of these polymers with other polymers (such as polyesters, polyurethanes, etc.), for example, block copolymers and graft copolymers. That is, the acrylic resin may be an acrylic-modified polyester resin or an acrylic-modified polyurethane resin. Further included are polymers (in some cases, mixtures of polymers) obtained by polymerizing polymerizable monomers in a polyester solution or a polyester dispersion. Similarly, polymers (in some cases, mixtures of polymers) obtained by polymerizing polymerizable monomers in a polyurethane solution or a polyurethane dispersion are included. Similarly, polymers (in some cases, polymer mixtures) obtained by polymerizing polymerizable monomers in other polymer solutions or dispersions are included, and these are also regarded as acrylic-modified polyester resins and acrylic-modified polyurethane resins in this specification. The above-mentioned polyesters and polyurethanes used in the acrylic resin can be appropriately selected and used from those exemplified as the above-mentioned binder components. Also, the acrylic resin may contain a hydroxyl group or an amino group in order to further improve the adhesion to the base film.

[0135] The above-mentioned polymerizable monomers are not particularly limited. Representative compounds include, for example, various carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, and their salts; various hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, monobutyl hydroxy fumarate, monobutyl hydroxy itaconate; various (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate; various nitrogen-containing compounds such as (meth)acrylamide, diacetone acrylamide, N-methylol acrylamide or (meth)acrylonitrile, etc.; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, and various vinyl esters such as vinyl propionate; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane; phosphorus-containing vinyl monomers; various vinyl halides such as vinyl chloride, vinylidene chloride; and various conjugated dienes such as butadiene.

[0136] In order to improve the strength of the resin layer (B), it is also possible to use a cross-linking agent in combination. As the cross-linking agent, conventionally known materials can be used, for example, oxazoline compounds, epoxy compounds, melamine compounds, isocyanate-based compounds, carbodiimide-based compounds, organosilicon compounds, etc. From the viewpoint of increasing the strength of the resin layer (B), melamine compounds are more preferable. Also, it is possible to use two or more cross-linking agents in combination.

[0137] The resin layer (B) in this release film can contain particles for the purpose of improving the slipperiness of the film, but a more preferable form is to substantially not contain particles. By substantially not containing particles in the resin layer (B), the release characteristics can be stabilized while reducing the migration property of the release component.

[0138] Note that "substantially free" means that the resin layer (B) may contain particles in a small amount as long as it does not inhibit the effects of the present invention. For example, particles that are inevitably mixed in may be included. The content of particles in the specific resin layer (B) is, based on the non-volatile component, less than 0.05% by mass, preferably less than 0.01% by mass, and more preferably less than 0.0001% by mass. Note that the range of the content of particles in the resin layer (B) based on the non-volatile component is the same as the above content of the particles.

[0139] Furthermore, within a range that does not impair the gist of the present invention, the resin layer (B) may contain, as necessary, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, a pigment, etc.

[0140] In the resin layer (B), the content of the release agent in the non-volatile component is preferably 10 to 70% by mass. When the content of the release agent is 10% by mass or more, good antiblocking performance can be obtained. When a long-chain alkyl group-containing compound is used as the non-silicone-based release agent in the resin layer (B), as a proportion in all the non-volatile components in the resin layer (B) composition, the long-chain alkyl group-containing compound is preferably in the range of 5 to 90% by mass, more preferably 10 to 70% by mass, still more preferably 20 to 60% by mass, and most preferably 20 to 40% by mass. When the proportion of the long-chain alkyl group-containing compound is within the above range, good antiblocking performance can be obtained, and by reducing the change in the peeling characteristics of the release layer due to blocking, the re-peeling of the release layer in the underwinding portion of the roll where pressure is applied to the film can be greatly suppressed.

[0141] In the resin layer (B), when wax is used as a non-silicone release agent, the proportion of wax in all non-volatile components in the resin layer (B) is preferably in the range of 5 to 90% by mass, more preferably 10 to 80% by mass, and even more preferably 25 to 70% by mass. When the proportion of wax is within the above range, good anti-blocking performance can be obtained, and by reducing the change in the peeling characteristics of the release layer due to blocking, the re-peeling of the release layer in the under-winding part of the roll where pressure is applied to the film can be greatly suppressed. Also, when used in combination with a melamine compound, re-peeling may progress. Therefore, when using wax, it is necessary to pay attention to the combination with a cross-linking agent or the like. On the other hand, the long-chain alkyl group-containing compound has no such problems as described below and can be said to be more preferable. As preferable combinations of compositions, combinations of a long-chain alkyl group-containing compound and a melamine compound, a long-chain alkyl group-containing compound and an oxazoline compound, a long-chain alkyl group-containing compound, a melamine compound and an oxazoline compound, and a wax, a melamine compound and an oxazoline compound are exemplified.

[0142] Regarding the factor (presumed) that the re-peeling rate increases depending on the combination with a cross-linking agent when wax is used as a non-silicone release agent rather than a long-chain alkyl group-containing compound, it is considered as follows. In addition to water repellency, wax has the characteristic of oil repellency. As a result, the compatibility with the combined melamine compound is poor, and the melamine compound is more likely to be repelled. On the other hand, in the evaluation of the re-peeling rate of the present invention, since the press treatment is performed in a state where moisture is interposed under high temperature (40°C) and high humidity (90% RH), aggregates are likely to be generated on the surface of the resin layer (B) in which wax and a melamine compound are combined. As a result of improving the adhesiveness with the silicone release layer on the opposite side, it is presumed that the re-peeling rate has increased. As described above, the present invention is characterized in that, paying attention to the oil repellent effect, which has not been focused on in conventional non-silicone release agents, a release agent is selected to constitute a release film provided with the resin layer (B).

[0143] In the resin layer (B), when a compound composed of thiophene or a thiophene derivative is used as an antistatic agent, the proportion of the compound composed of thiophene or a thiophene derivative in the total non-volatile components of the resin layer (B) is preferably in the range of 5 to 50% by mass, more preferably 5 to 40% by mass, and still more preferably 5 to 30% by mass. When it is in the above range, good antistatic properties can be obtained.

[0144] In the resin layer (B), the polyhydroxy compound is preferably in the range of 10 to 80% by mass, more preferably 20 to 70% by mass, and still more preferably 30 to 65% by mass in the proportion of the total non-volatile components of the resin layer (B). When it is in the above range, good antistatic properties can be obtained.

[0145] As the proportion in the total non-volatile components of the resin layer (B), the binder component is preferably in the range of 5 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 5 to 30% by mass. When the proportion of the binder component is in the above range, the strength of the resin layer (B) is good and blocking can be reduced.

[0146] As the proportion in the total non-volatile components of the resin layer (B), the crosslinking agent is preferably in the range of 5 to 70% by mass, preferably 10 to 60% by mass, and even more preferably 15 to 50% by mass. When the proportion of the crosslinking agent is in the above range, the strength of the resin layer (B) is good and blocking can be reduced.

[0147] <Properties of Resin Layer (B)> The resin layer (B) in the present invention can have the following properties.

[0148] In this release film, the surface roughness (Ra(B)) of the resin layer (B) is preferably 20 nm or more, more preferably in the range of 25 to 60 nm, still more preferably in the range of 30 to 55 nm, and even more preferably in the range of 38 to 50 nm. When it is 20 nm or more, blocking is less likely to occur in the state of a roll after providing the release layer. On the other hand, when the surface roughness is 60 nm or less, when this release film is wound into a roll, the unevenness of the film is not transferred to the release layer, and the release characteristics of the release layer are maintained.

[0149] The thickness of the resin layer (B) is preferably 0.005 to 0.25 μm, more preferably 0.008 to 0.15 μm, and even more preferably 0.01 to 0.10 μm. By setting the thickness of the resin layer (B) to 0.25 μm or less, the migration of the non-silicone-based release agent component in the resin layer (B) to the release layer is suppressed when this release film is wound into a roll. If the thickness of the resin layer (B) is 0.005 μm or more, good blocking prevention properties can be imparted. It is presumed that unreacted substances of various compounds, compounds after reaction, or mixtures thereof are present in the resin layer (B).

[0150] The surface resistivity of the surface of the resin layer (B) is preferably 1×10 12 Ω / square or less, more preferably 1×10 10 Ω / square or less, still more preferably 1×10 8 Ω / square or less, and most preferably 1×10 6 Ω / square or less. There is no particular lower limit for the surface resistivity, but considering the cost of the antistatic agent, it is preferably 1×10 4 Ω / square or more. The lower the surface resistivity of the resin layer (B), the better the antistatic property, and it is possible to suppress the charging of the film in the process and prevent the adhesion of foreign substances and the like.

[0151] The normal peel strength of the resin layer (B) is preferably 400 to 2000 g / 25 mm, more preferably 400 to 1500 g / 25 mm, and still more preferably 400 to 1000 g / 25 mm. By setting the normal peel strength of the resin layer (B) to 2000 g / 25 mm or less, good antiblocking property can be imparted, and when the present release film is wound into a roll, delamination of the resin layer (A) in the underwound portion of the roll where pressure is applied by the film can be suppressed.

[0152] The surface free energy of the resin layer (B) is preferably 50 mN / m or less, more preferably 40 mN / m or less, and still more preferably 30 mN / m or less. By setting the surface free energy of the resin layer to 50 mN / m or less, good antiblocking property can be imparted, and when the present release film is wound into a roll, delamination of the release layer (A) in the underwound portion of the roll where pressure is applied by the film can be suppressed. Details of the surface free energy are as described in the examples.

[0153] The elastic modulus of the resin layer (B) at 25°C is preferably 500 MPa or more. The elastic modulus referred to here is the value measured by a nanoindenter. When the elastic modulus is 500 MPa or more, delamination of the resin layer (A) does not occur even in the underwound portion of the roll where pressure is applied by the film when the present release film is wound into a roll.

[0154] <Undercoat layer> It is preferable that the present release film is provided with an undercoat layer between at least one of the resin layer (A) or the resin layer (B) and the base film. The undercoat layer may be provided either between the resin layer (A) and the base film or between the resin layer (B) and the base film, or may be provided on both.

[0155] The undercoat layer is used not only for the purpose of improving the adhesion between the film and the resin layer (A) or the resin layer (B), but also for the purpose of imparting various functions to the release film. As the undercoat layer, for example, in the process of peeling a functional layer such as an adhesive layer provided on the resin layer (A), antistatic performance for suppressing peeling charge and preventing adhesion of foreign matters, etc., and when performing heat treatment at high temperature for a long time, oligomer sealing performance for sealing the precipitation of oligomers from the polyester film can be mentioned. In this release film, it is preferable that the undercoat layer has antistatic performance. Note that the undercoat layer may be a single layer or a configuration of two or more layers.

[0156] As the antistatic agent in the undercoat layer having antistatic performance, for example, a polymer doped with another anionic compound in a compound composed of the thiophene or thiophene derivative, or a polymer self-doped with an anionic group in a compound composed of a thiophene or thiophene derivative, or a polymer containing a monomer having an alkylsulfonate ion as a counter ion as a component can be used. In addition, in this release film, from the viewpoint of having good antistatic performance, it is more preferable that the undercoat layer contains a compound composed of a thiophene or thiophene derivative.

[0157] For forming the undercoat layer having antistatic performance, for the purpose of improving the antistatic performance, it is preferable to use one or more compounds selected from the polyglycerin represented by the general formula (9) and the alkylene oxide adduct to polyglycerin or its derivative.

[0158] The undercoat layer having antistatic performance may contain a binder component. As the binder, various conventionally known polymers such as polyester resin, acrylic resin, urethane resin, polyvinyl alcohol resin, etc. can be used. From the viewpoints of transparency and improvement of antistatic property of the undercoat layer, urethane resin is preferable.

[0159] In order to improve the strength of the undercoat layer, it is also possible to use a crosslinking agent in combination. As the crosslinking agent, conventionally known materials can be used. For example, oxazoline compounds, epoxy compounds, melamine compounds, isocyanate compounds, carbodiimide compounds, organosilicon compounds, etc. can be mentioned. From the viewpoint of increasing the strength of the undercoat layer, melamine compounds are more preferable. It is also possible to use two or more kinds of crosslinking agents in combination.

[0160] When a compound composed of thiophene or a thiophene derivative is used as an antistatic agent in the undercoat layer, the proportion of the compound composed of thiophene or a thiophene derivative in the total non-volatile components of the undercoat layer is preferably in the range of 5 to 50% by mass, more preferably 5 to 40% by mass, and still more preferably 5 to 30% by mass. When it is within the above range, good antistatic properties can be obtained.

[0161] In the undercoat layer, one or more compounds selected from polyglycerin and alkylene oxide adducts to polyglycerin or derivatives thereof, as the proportion in the total non-volatile components of the undercoat layer, are preferably in the range of 10 to 80% by mass, more preferably 20 to 70% by mass, and still more preferably 30 to 65% by mass. When it is within the above range, good antistatic properties can be obtained.

[0162] As the proportion in the total non-volatile components of the undercoat layer, the binder component is preferably in the range of 5 to 50% by mass, more preferably 5 to 40% by mass, and still more preferably 5 to 30% by mass. When the proportion of the binder component is within the above range, the strength of the undercoat layer is good and the antistatic property can be made good.

[0163] As the proportion in the total non-volatile components of the undercoat layer, the crosslinking agent is preferably in the range of 5 to 70% by mass, preferably 10 to 60% by mass, and still more preferably 15 to 50% by mass. When the proportion of the crosslinking agent is within the above range, the strength of the undercoat layer is good and blocking can be reduced.

[0164] For the undercoat layer having oligomer blocking performance, an undercoat layer having oligomer blocking performance containing an organic compound containing one or more metal elements selected from aluminum, titanium, and zirconium may be provided.

[0165] The undercoat layer having oligomer blocking performance may be provided directly on the base film or on the undercoat layer having antistatic performance.

[0166] It can be presumed that unreacted substances, compounds after reaction, or mixtures thereof of various compounds of the resin composition are present in the undercoat layer.

[0167] <Properties of the undercoat layer> The thickness of the undercoat layer having antistatic performance is preferably 0.005 μm or more and 0.25 μm or less, more preferably 0.008 μm or more and 0.15 μm or less, and still more preferably 0.01 μm or more and 0.10 μm or less. If the thickness of the undercoat layer is within the above range, good antistatic performance can be imparted.

[0168] The surface resistivity of the surface of the undercoat layer having antistatic performance is preferably 1×10 12 Ω / □ or less, more preferably 1×10 10 Ω / □ or less, still more preferably 1×10 8 Ω / □ or less, and most preferably 1×10 6 Ω / □ or less. There is no particular lower limit for the surface resistivity, but considering the cost of the antistatic agent, it is preferably 1×10 4 Ω / □ or more. The lower the surface resistivity of the resin layer (B), the better the antistatic performance, and it is possible to suppress the charging of the film in the process and prevent the adhesion of foreign substances and the like.

[0169] <Method for forming the resin layer (B) and the undercoat layer> Next, the method for forming the resin layer (B) and the undercoat layer will be described.

[0170] The resin layer (B) and the undercoat layer are formed by coating a coating liquid on the film, and may be provided by in-line coating performed within the film manufacturing process, or may employ so-called off-line coating which is applied outside the system on a once-manufactured film. More preferably, it is in-line coating.

[0171] In-line coating is a method of performing coating within the process of manufacturing a polyester film. Specifically, it is a method of performing coating at any stage from when the polyester is melt-extruded until after stretching and heat setting and winding up. Usually, coating is performed on any one of the unstretched sheet obtained by melting and quenching, the uniaxially stretched film that has been stretched, the biaxially stretched film before heat setting, and the film after heat setting and before winding up. Although not limited to the following, for example, in sequential biaxial stretching, a method of coating an uniaxially stretched film stretched particularly in the longitudinal direction (vertical direction) and then stretching it in the lateral direction is excellent. According to such a method, film formation and formation of the resin layer (B) can be performed simultaneously, which has an advantage in terms of manufacturing cost. Also, since stretching is performed after coating, the thickness of the resin layer (B) can be changed according to the stretching ratio, and thin film coating can be performed more easily compared to an off-line coating film. Further, by providing the resin layer (B) on the film before stretching, the resin layer (B) can be stretched together with the polyester film, thereby firmly adhering the resin layer (B) to the polyester film. Furthermore, in the manufacture of a biaxially stretched polyester film, by stretching while gripping the film end with a clip or the like, the film can be constrained in the longitudinal and lateral directions, and in the heat setting process, a high temperature can be applied while maintaining flatness without wrinkles. Therefore, since the heat treatment performed after coating can be at a higher temperature than achieved by other methods, the curing of the resin layer (B) and the undercoat layer progresses more compared to off-line coating, and a stronger coating film can be made.

[0172] When providing the resin layer (B) by inline coating, it is preferable to produce the base film by applying a resin layer (B) composition, in which the above-described series of compounds is used as an aqueous solution or an aqueous dispersion and the solid content concentration (total nonvolatile components) is adjusted to about 0.1 to 50% by mass, onto a polyester film.

[0173] As a method for applying the resin layer (B) composition or the undercoat layer composition to the film, for example, conventionally known coating methods such as air doctor coating, blade coating, rod coating, bar coating, knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss roll coating, cast coating, spray coating, curtain coating, calendar coating, and extrusion coating can be used.

[0174] Regarding the drying and curing conditions when forming the resin layer (B) and the undercoat layer on the film, there are no particular limitations. When providing the resin layer (B) by inline coating, preferably, heat treatment is performed at 70 to 270°C for 3 to 200 seconds, more preferably at 100 to 260°C, still more preferably at 110 to 250°C, with 10 to 100 seconds as a guide.

[0175] On the other hand, for example, when providing the resin layer (B) by offline coating, preferably, heat treatment is performed at 80 to 200°C for 3 to 40 seconds, more preferably at 100 to 180°C for 3 to 40 seconds as a guide.

[0176] Regardless of offline coating or inline coating, heat treatment and irradiation with active energy rays such as ultraviolet irradiation may be used in combination as necessary. The film constituting the release film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

[0177] <<Laminated Structure of Release Film>> The release film in the present invention may be in a laminated structure. A preferred form is a form in which an adhesive layer is laminated on the surface of the release film on the resin layer (A) side. A more preferred form is to use the present release film as the first release film, an adhesive layer on the resin layer (A) side of the present release film, and on the other surface of the adhesive layer to which the resin layer (A) of the present release film is bonded, a release film having a release force different from that of the present release film is used as the second release film, and the bonded one is mentioned. A still more preferred form is one in which the adhesive layer is an optically transparent adhesive sheet (OCA), and the present release film is used and bonded as a release film on the side with a light release force. Note that the adhesive layer may be a single layer or a structure of two or more layers. Further, the "release film having a release force different from that of the present release film" means that the release force of the release film evaluated by the measurement method as described in the examples is different from the release force on the resin layer (A) side of the present release film. Also, as the release film having a release force different from that of the present release film, it is preferably greater than the release force of the resin layer (A) of the present release film. Specifically, those having a release force of 1.5 to 10 times are preferred, those having a release force of 1.5 to 8 times are more preferred, and those having a release force of about 1.5 to 6 times are still more preferred. By satisfying the release force, it is possible to reduce the problem of peeling in a situation where the resin layer (A) of the present release film does not need to peel originally.

[0178] <Adhesive layer> Regarding the adhesive layer, it will be described below. The adhesive layer is a layer made of an adhesive composition, and may be an acrylic adhesive composition having an acrylic resin as the main component resin, a rubber-based adhesive composition having rubber as the main component, a urethane-based adhesive composition having a urethane resin as the main component, or a silicone-based adhesive composition having a silicone resin as the main component. Among them, the adhesive composition is preferably an acrylic adhesive composition having an acrylic resin as the main component because it can adjust the adhesive force and the release force in a well-balanced manner and is inexpensive. The "main component resin" mentioned above means the resin with the highest mass ratio among the resins constituting the pressure-sensitive adhesive composition. For example, it means a component that occupies 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more of the total amount of the resins constituting the pressure-sensitive adhesive composition. The upper limit is 100% by mass, but it is usually 99.99% by mass.

[0179] (Acrylic resin) Examples of the acrylic resin that is the main component resin of the pressure-sensitive adhesive composition include (meth)acrylic polymers. (Meth)acrylic polymers are polymers having (meth)acrylic acid alkyl esters as main structural units. Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, isobornyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, adamantyl (meth)acrylate, and the like. These may be used alone or in combination of two or more. Among these, methyl (meth)acrylate is preferred from the viewpoints of compatibility with other (meth)acrylates constituting the (meth)acrylic polymer and heat resistance of the cured resin layer (B). The content ratio of (meth)acrylic acid alkyl ester in the monomer forming the (meth)acrylic polymer is, for example, 50% by mass or more, preferably 60 to 99.99% by mass, more preferably 75 to 98.9% by mass, and still more preferably 87 to 97.8% by mass. The (meth)acrylic polymer may have a radically polymerizable double bond.

[0180] (Meth)acrylic polymers can copolymerize (meth)acrylic esters other than (meth)acrylic acid alkyl esters, (meth)acrylic acid, and other compounds having a vinyl group for the purpose of improving glass transition temperature, mechanical properties, compatibility, etc. Examples of the (meth)acrylic esters other than the (meth)acrylic acid alkyl esters that can be used as copolymerization components include (meth)acrylic acid hydroxyalkyl, (meth)acrylic acid methoxymethyl, (meth)acrylic acid methoxyethyl, (meth)acrylic acid ethoxymethyl, (meth)acrylic acid ethoxyethyl, and other (meth)acrylic acid alkoxyalkyl esters, (meth)acrylic acid phenyl, (meth)acrylic acid benzyl, (meth)acrylic acid glycidyl, (meth)acrylic acid γ-butyrolactone, and the like, which will be described later. Examples of the compounds having a vinyl group include acrylamide compounds such as dimethylacrylamide, hydroxyethylacrylamide, and dimethylaminopropylacrylamide, styrene compounds such as styrene, α-methylstyrene, and p-methoxystyrene, and maleic anhydride. In addition, the (a1) component and (a2) component described later, which are other than these, can also be appropriately used.

[0181] In the present invention, the monomers constituting the (meth)acrylic polymer may contain acrylic monomer (a1) as a copolymerization component in addition to the (meth)acrylic acid alkyl ester, in terms of a reaction point with a crosslinking agent described later.

[0182] When the acrylic monomer (a1) is copolymerized with other copolymerization components to form an acrylic resin, it serves as a reaction point for the crosslinked structure. A monomer containing a functional group capable of reacting with the functional group contained in the crosslinking agent described later may be used. Examples of such an acrylic monomer (a1) include a hydroxyl group-containing monomer, an amino group-containing monomer, an acetoacetyl group-containing monomer, an isocyanate group-containing monomer, a glycidyl group-containing monomer, and the like. Among these, a hydroxyl group-containing monomer is preferably used in terms of its ability to efficiently undergo a crosslinking reaction with the crosslinking agent. The acrylic monomer (a1) may be used alone or in combination of two or more.

[0183] Examples of the hydroxyl group-containing monomer include hydroxyalkyl acrylates such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate; caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate; oxyalkylene-modified monomers such as diethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate; primary hydroxyl group-containing monomers such as 2-acryloyloxyethyl 2-hydroxyethyl phthalate, N-methylol (meth)acrylamide; secondary hydroxyl group-containing monomers such as 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate; and tertiary hydroxyl group-containing monomers such as 2,2-dimethyl-2-hydroxyethyl (meth)acrylate.

[0184] Among the above hydroxyl group-containing monomers, a primary hydroxyl group-containing monomer is preferred in terms of its excellent reactivity with the crosslinking agent. Furthermore, the use of 2-hydroxyethyl acrylate is particularly preferred in terms of having fewer impurities such as di(meth)acrylate and being easy to manufacture.

[0185] In addition, as the hydroxyl group-containing monomer used in the present invention, it is also preferable to use one having a content ratio of di(meth)acrylate, which is an impurity, of 0.5% by mass or less, and more preferably 0.2% by mass or less, particularly preferably 0.1% by mass or less. Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, etc., which are particularly preferable because they have a low molecular weight and are easy to purify.

[0186] Examples of the amino group-containing monomer include t-butylaminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and the like.

[0187] Examples of the acetoacetyl group-containing monomer include 2-(acetoacetoxy)ethyl (meth)acrylate, allyl acetoacetate, and the like.

[0188] Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and their alkylene oxide adducts, and the like.

[0189] Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate, allyl glycidyl (meth)acrylate, and the like.

[0190] The content of the acrylic monomer (a1) in the monomers constituting the (meth)acrylic polymer is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and particularly preferably 0.2 to 3% by mass. When the acrylic monomer (a1) is at least the above lower limit value, the crosslinking points at the time of crosslinking become appropriate, so that the cohesive force after crosslinking becomes good. Further, when it is at most the above upper limit value, it is possible to prevent the adhesive force from decreasing due to the component (a1).

[0191] In addition, the monomer constituting the (meth)acrylic polymer may contain, in addition to the (meth)acrylic acid alkyl ester or the (meth)acrylic acid alkyl ester and the component (a1), a copolymerizable monomer (a2) other than (a1) as a copolymerization component, if necessary. Examples of the copolymerizable monomer (a2) include aromatic ring-containing monomers such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, ethoxylated o-phenylphenyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and styrene; amide-based monomers such as (meth)acryloylmorpholine, dimethyl (meth)acrylamide, diethyl (meth)acrylamide, and (meth)acrylamide; acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, dialkyl itaconate, dialkyl fumarate, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, and the like.

[0192] The content ratio of the copolymerizable monomer (a2) in the monomer forming the (meth)acrylic polymer is preferably 0 to 20% by mass, more preferably 1 to 15% by mass, and particularly preferably 2 to 10% by mass. When the content of the copolymerizable monomer (a2) is within the above range, it is possible to prevent the adhesion characteristics from deteriorating due to the component (a2). In the present invention, from the viewpoint of imparting flexibility to the adhesive layer in consideration of the application to a foldable display, it is preferable to contain 2-ethylhexyl acrylate and / or butyl acrylate.

[0193] In addition to the above main component resin, the pressure-sensitive adhesive composition may contain, as necessary, a crosslinking agent and resins (for example, acrylic resins, rubbers, silicone resins, urethane resins) that constitute other (excluding the main component resin and the crosslinking agent) pressure-sensitive adhesive components.

[0194] (Crosslinking agent) The pressure-sensitive adhesive composition can contain a crosslinking agent according to its curing method. Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, aldehyde-based crosslinking agents, amine-based crosslinking agents, etc. Among them, isocyanate-based crosslinking agents are preferably used in terms of improving adhesion to the substrate or reactivity with acrylic resins. The crosslinking agent may be used alone or in combination of two or more. The content of the crosslinking agent is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and particularly preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the main component resin. When the content of the crosslinking agent is within the above range, the cohesive force will not be insufficient, and the desired durability can be obtained, while the flexibility and adhesive strength can be prevented from decreasing.

[0195] Regarding the curing reaction, in the case of photocuring by irradiating active energy rays, it is preferable to blend polyfunctional (meth)acrylate as a crosslinking agent in the pressure-sensitive adhesive composition. Examples of such polyfunctional (meth)acrylate include trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerin polyglycidyl ether poly(meth)acrylate, etc.

[0196] (Resins constituting other pressure-sensitive adhesive components) In addition to the above main component resin and crosslinking agent, the pressure-sensitive adhesive composition may contain, if necessary, resins (e.g., acrylic resins, rubbers, silicone resins, urethane resins) that constitute pressure-sensitive adhesive components other than the main component resin and crosslinking agent. For example, tackifiers such as rosin, rosin ester, hydrogenated rosin ester, phenolic resin, aromatic-modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin, etc., silane coupling agents, antistatic agents, coloring agents, fillers, antioxidants, ultraviolet absorbers, conventionally known additives such as functional pigments, and additives such as compounds that cause color development or discoloration upon ultraviolet or radiation irradiation can be blended. The blending amount of these additives is preferably 10% by mass or less based on the total amount of the pressure-sensitive adhesive composition (non-volatile component basis), more preferably 5% by mass or less, and it is preferable in terms of excellent durability that low molecular components having a molecular weight lower than 10,000 are not contained as much as possible as additives.

[0197] <Method for forming the pressure-sensitive adhesive layer> The method for forming the pressure-sensitive adhesive layer is not particularly limited. After applying the above pressure-sensitive adhesive composition on the resin layer (A) of the present release film, it may be appropriately dried and cured, etc. Also, after applying the pressure-sensitive adhesive composition on a base film or a release film having a different peeling force from the present release film, appropriately drying and curing it, etc., the release layer (A layer) of the present release film may be bonded to the surface opposite to the surface provided with the release film having a different peeling force from the present release film. The pressure-sensitive adhesive composition may be cured according to the crosslinking agent and the main component resin, and may be cured by heating or by light irradiation such as ultraviolet rays. Also, the above pressure-sensitive adhesive composition may be diluted with an appropriate organic solvent, etc. and then applied on a release layer, etc.

[0198] <Properties of the pressure-sensitive adhesive layer> (Thickness of the pressure-sensitive adhesive layer) The thickness of the adhesive layer is not particularly limited. For example, from the viewpoints of imparting sufficient adhesive force and filling unevenness and steps of the base material to which the adhesive is bonded, it is preferably 0.1 μm or more, more preferably 0.5 μm or more, and still more preferably 1 μm or more. On the other hand, from the viewpoints of material use efficiency, transmittance, and outgassing, it is preferably 10000 μm or less, more preferably 3000 μm or less, and still more preferably 1000 μm or less.

[0199] (Elastic modulus of the adhesive layer) In the present invention, the elastic modulus of the adhesive layer at 25 °C is preferably 6.0 MPa or less. The elastic modulus referred to here is a value measured by a nanoindenter. By setting the elastic modulus to 6.0 MPa or less, the adhesive layer has good followability to deformation and can be applied to foldable display applications. From these viewpoints, the elastic modulus of the adhesive layer is more preferably 5.0 MPa or less, still more preferably 4.0 MPa or less, and particularly preferably 3.0 MPa or less. Further, from the viewpoint of the formability of the adhesive layer, the elastic modulus of the adhesive layer at 25 °C is preferably 0.5 MPa or more, more preferably 1.0 MPa or more, and still more preferably 1.5 MPa or more.

[0200] (Glass transition temperature (Tg) of the adhesive layer) The glass transition temperature is calculated from the following Fox's formula. TIFF0007708319000009.tif1584 Tg: Glass transition temperature of the copolymer (K) Tga: Glass transition temperature of the homopolymer of monomer A (K) Wa: Weight fraction of monomer A Tgb: Glass transition temperature of the homopolymer of monomer B (K) Wb: Weight fraction of monomer B Tgn: Glass transition temperature of the homopolymer of monomer N (K) Wn: Weight fraction of monomer N (Wa + Wb + ··· + Wn = 1)

[0201] In the present invention, considering the application to a foldable display, the Tg is preferably in the range of -55°C to -70°C, more preferably in the range of -58°C to -68°C. By satisfying the above range, an adhesive layer with good followability to deformation such as bending can be obtained.

[0202] <<Method of using the film laminate>> This film laminate can be used in various laminate configurations. For example, the release film with the adhesive layer may be a film laminate in which an optical member is bonded to the surface of the adhesive layer. Such a film laminate can be prepared by peeling off this release film and bonding the optical member to the adherend with the exposed adhesive layer. Examples of the optical member include a polarizing plate, a touch sensor, etc. It may also be an in-vehicle optical member such as a touch panel mounted on an automobile.

[0203] (Polarizing plate) The material and configuration of the polarizing plate are arbitrary. For example, a stretched polyvinyl alcohol film using iodine as an alignment dye and laminated with a TAC (triacetyl cellulose) film as a protective film is widely used as this type of polarizing plate. Also, the polarizing plate may have a layer configuration with functions such as a hard coat having substantially no retardation, antiglare, low reflection, and antistatic on its surface.

[0204] (Touch sensor) A touch sensor is a member that grasps the touch point in response to the contact when a user touches an image displayed on the screen with a finger, a touch pen, etc. Examples of methods using sensor technology include the capacitance method, the resistive film method, and the surface wave method using infrared rays or ultrasonic waves. Generally, a touch sensor is mounted on a display device such as a liquid crystal display panel or an organic EL. In recent years, as an alternative to glass substrates, attention has been paid to flexibility, and there is a tendency to use a base film, and it is preferable to use a touch sensor film. The touch sensor film generally has a patterned transparent conductive layer for performing the function of the sensing electrode.

[0205] In addition, the film laminate may include the above-described release film with an adhesive layer and another release film, and may have a layer structure in which the release film with an adhesive layer is bonded to the other release film via the adhesive layer. The film laminate having such a layer structure is composed of the present release film / adhesive layer / other release film configuration and can be used as a double-sided adhesive sheet. The other release film is one in which a release layer is formed on the surface of a base material such as a resin film, and the surface on which the release layer is formed is preferably bonded to the adhesive layer. As the release layer of the other release film, those other than the above-described present release layer may be used.

[0206] In the film laminate having the above structure, the ratio (MB / MA) of the elastic modulus (MA) of the release layer of the present release film to the elastic modulus (MB) of the release layer of the other release film is preferably in the range of 4 to 30, more preferably in the range of 4 to 25. By satisfying the above range of the elastic modulus, in the film laminate, in a situation where peeling is not originally required, the problem of peeling of the present release film can be reduced.

[0207] For the film laminate to which the above-described other release film is bonded, it is preferable to use it by peeling the present release film and bonding the exposed adhesive layer surface of the remaining release film with an adhesive layer to an optical member. Then, thereafter, the other release film may be peeled from the adhesive layer of the release film with an adhesive layer. Further, thereafter, the present release film can also be bonded again onto the adhesive layer bonded to the optical member. Since the release film of the present invention has ultra-low peelability and low transferability, so-called re-peeling use of the release film is also possible.

[0208] In addition, for other release films, the normal release force measured by 180° peeling at a peeling speed of 0.3 m / min is preferably greater than the normal release force of this release film, specifically about 2 to 10 times, more preferably 2 to 6 times the normal release force of this release film. By satisfying the peeling force ratio, it is possible to reduce the problem that this release film peels off in a scene where it should not originally peel off.

[0209] The above-mentioned release film and film laminate are preferably used for in-vehicle applications. When used for in-vehicle applications, in order to maintain high adhesiveness even when exposed to a high-temperature atmosphere in summer or a low-temperature environment in winter, it is necessary to increase the adhesiveness of the adhesive layer. Since this release film can achieve ultra-light peelability, the peelability is good even if the adhesiveness of the adhesive layer is high.

[0210] <<<Explanation of terms, etc.>>> In the present invention, when referring to "film", it includes "sheet", and when referring to "sheet", it includes "film". Also, when expressing as "panel" such as an image display panel, a protection panel, a touch panel, etc., it includes a plate body, a sheet, and a film.

[0211] In the present invention, when described as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also the meaning of "preferably greater than X" or "preferably less than Y". Also, when described as "X or more" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably greater than X", and when described as "Y or less" (Y is an arbitrary number), unless otherwise specified, it also includes the meaning of "preferably less than Y".

Examples

[0212] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The evaluation methods in the examples and comparative examples are as follows.

[0213] (1) Method for measuring the intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with the polyester were removed was precisely weighed, 100 ml of a mixed solvent of phenol / tetrachloroethane = 50 / 50 (mass ratio) was added and dissolved, and the measurement was carried out at 30°C.

[0214] (2) Method for measuring the average particle size (d50: μm) The value at 50% of the integration (mass basis) in the equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) was taken as the average particle size.

[0215] (3) Method for measuring the film thickness of the resin layer (A) In order to suppress the reflection from the back surface, black tape ("Vinyl Tape VT-50" manufactured by Nichiban Co., Ltd.) was previously attached to the measurement back surface of the sample film. For the measurement, an absolute reflectance in the wavelength range of 300 to 800 nm was measured using a spectrophotometer (Ultraviolet-Visible Spectrophotometer "V-670" manufactured by JASCO Corporation) under the conditions of synchronous mode, incident angle of 5°, N-polarization, response Fast, data acquisition interval of 1.0 nm, bandwidth of 10 nm, and scanning speed of 1000 m / min. The film thickness was determined by comparing the data obtained in this measurement with the data calculated assuming the refractive index of silicone to be 1.43.

[0216] (4) Method for measuring the film thickness of the resin layer (B) and the undercoat layer The surface of the cured resin layer (B) was stained with RuO4 and embedded in an epoxy resin. Thereafter, the section prepared by the ultra-thin section method was stained with RuO4, and the cross-section of the coating layer was measured using a TEM (H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 kV).

[0217] (5) Measurement of surface resistivity Using a low resistivity meter (manufactured by Mitsubishi Chemical Corporation, "Loresta GP MCP-T600"), after conditioning the sample for 30 minutes in a measurement atmosphere of 23°C and 50% relative humidity, the surface resistivity was measured, and the value after 1 minute was taken as the surface resistivity. If the resistance value exceeded the upper limit of the measurable range, the measurement was considered impossible.

[0218] (6) Measurement of average surface roughness Using a surface roughness meter conforming to JIS B 0601-2001 (manufactured by Kosaka Laboratory Ltd., two-dimensional roughness meter "surfcorder SE3500"), the arithmetic mean roughness (Ra) of the resin layer (B) was measured. Also, the maximum cross-sectional height (Rt) of the anti-release surface was measured. Rt can be obtained as the sum of the maximum value of the peak height Rp and the maximum value of the valley depth Rv of the roughness curve in the evaluation length.

[0219] (7) Measurement of the molecular weight of the curable silicone resin Using a GPC measuring device, a chromatogram was measured, and the number average molecular weight (Mn) and mass average molecular weight (Mw) were determined based on a calibration curve using standard polystyrene and shown in Table 2. Specifically, 4 mg of the sample for measurement was dissolved in 4 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into the GPC measuring device for measurement. Tetrahydrofuran (THF) was used as the eluent. For the analysis, "Ecosec8320" manufactured by Tosoh Corporation was used, and for the guard column, "TSKgel guardcolumn HXL-L" manufactured by Tosoh Corporation and for the column, four "TSKgel GMHXL" manufactured by Tosoh Corporation were connected in series and used. Also, the analysis was carried out under the conditions of an oven temperature of 40°C and a THF flow rate of 1.0 mL / min, and RI was used for detection.

[0220] (8) Composition analysis of the curable silicone resin The composition analysis of the curable silicone resin used in the examples and comparative examples was carried out using a 400 MHz-NMR (Bruker Avance400M). 1 For 1H-NMR measurement, CDCl3 was used as the solvent, and the measurement was carried out at 30°C with reference to the peak derived from the methyl group of dimethylsiloxane as the chemical shift.

[0221] (9) Measurement of the normal peel strength of the resin layer (A) On the resin layer (A) surface of the sample film, it was pressure-bonded (2 reciprocations) with a rubber roller (2 kg), and after sticking an adhesive tape (Tesa's "No. 7475"), it was cut into a size of 25 mm × 300 mm and left at room temperature (23 °C) for 1 hour, and then the peel strength was measured. The measurement of the peel strength was carried out using "Intesco Model 2001 type" manufactured by Intesco Co., Ltd., with the sample film peeled at 180° under the condition of a tensile speed of 0.3 m / min.

[0222] (10) Measurement of the residual adhesion rate of the resin layer (A) (evaluation of migration) The sample film was cut into A4 size (210 mm × 297 mm), and a 75-μm biaxially stretched PET film (manufactured by Mitsubishi Chemical Corporation: Diafoil T100-75) was overlaid on the release layer (A layer) surface, and pressed for 2 hours under the conditions of a temperature of 23 °C and a pressure of 1 MPa. Then, the "75-μm biaxially stretched PET film" alone was used as the evaluation film. On the other hand, the same "75-μm biaxially stretched PET film" was overlaid on an untreated base film without the resin layer (A) and pressed under the same conditions as above, and the "75-μm biaxially stretched PET film" alone was used as the reference film. On the contact surface of the evaluation film with the sample film (resin layer (A) (A layer)) and the contact surface of the reference film with the base film, an adhesive tape (Nitto Denko Corporation's "No. 31B") was stuck by pressure-bonding (2 reciprocations) with a rubber roller (2 kg) respectively, then cut into a size of 50 mm × 300 mm, and the peel strength after leaving at room temperature for 1 hour was measured. The measurement of the peel strength was carried out using "Intesco Model 2001 type" manufactured by Intesco Co., Ltd., with the evaluation film and the reference film peeled at 180° respectively under the condition of a tensile speed of 0.3 m / min. Then, the measured peel strength of the evaluation film and the peel strength of the reference film were substituted into the following formula to obtain the residual adhesion rate (%). Here, it is the value without treatment such as heat treatment. Residual adhesion rate (%) = (Peel strength of evaluation film / Peel strength of reference film) × 100

[0223] In the case of a highly migratory film, a large amount of silicone adheres to the overlapped films, resulting in a decrease in the peel strength of the adhesive tape and a decrease in the residual adhesion rate (%). Therefore, the migration property of the resin layer (A) of the release film was evaluated as follows based on the value of the residual adhesion rate.

[0224] (11) Post-press re-peeling rate of the resin layer (A) (substitute evaluation of blocking property) After an acrylic adhesive tape ("No. 7475" manufactured by Tesa) was attached to the resin layer (A) surface of the release films of the examples and comparative examples, it was cut into a size of 25 mm × 150 mm and left at room temperature for 1 hour. The peel strength peeled at 180° under the condition of a tensile speed of 0.3 m / min is designated as (F1). Next, on the resin layer (A) surface of the release films of the examples and comparative examples, it was arranged so that the other surface (in the present invention, the resin layer (B) surface) faced each other, and press treatment was performed at a temperature of 40°C, a humidity of 90% RH, and a load of 1 MPa for 20 hours. After an acrylic adhesive tape ("No. 7475" manufactured by Tesa) was attached to the resin layer (A) surface after the treatment, it was cut into a size of 25 mm × 150 mm and left at room temperature for 1 hour. The peel strength peeled at 180° under the condition of a tensile speed of 0.3 m / min is designated as (F2). The post-press re-peeling rate was determined by the following formula, and the re-peeling rate at this time was used as an index of blocking resistance. Note that the blocking resistance is judged to be better as the re-peeling rate is smaller. Post-press re-peeling rate (%) = (F2 - F1) / F1 × 100

[0225] (12) Blocking property evaluation The release film surfaces and the anti-release film surfaces of the examples and comparative examples were arranged so as to face each other, and a pressure of 10 kg / cm was applied with a press machine. 2Under the atmosphere of 40°C and 80% RH, pressure was applied for 20 hours to obtain a measurement sample for evaluating blocking resistance. Then, using a peeling device ("AGI" manufactured by Shimadzu Corporation), the peeling force was measured under the conditions of a peeling speed of 300 mm / min and 180° peeling. The peeling force at this time was used as an index for blocking resistance. Note that the smaller the peeling force, the better the blocking resistance is judged to be. 《Evaluation Criteria》 A (good): The peeling force is 20 g / 25 mm or less, and peeling is possible without problems. B (poor): The peeling force exceeds 20 g / 25 mm, and blocking occurs.

[0226] (13) Adhesion between the base film and resin layer (A) In a thermostatic and humidistatic chamber, after leaving the sample film in an atmosphere of 60°C and 80% RH for 4 weeks, the sample film was taken out. Then, the surface of the resin layer (A) of the sample film was rubbed 5 times by hand, and the adhesion was evaluated according to the following evaluation criteria based on the degree of peeling of the release layer. 《Evaluation Criteria》 〇: The coating film did not turn white and no peeling was observed. ×: The coating film turned white or peeling was confirmed.

[0227] (14) Measurement of the normal peeling force of resin layer (B) An acrylic adhesive tape ("No. 7475" manufactured by Tesa) was attached to the resin layer (B) of the sample film by pressing with a rubber roller (2 kg) (2 round trips). After cutting it into a size of 25 mm × 150 mm and leaving it at room temperature (23°C) for 1 hour, the peeling force was measured. The measurement of the peeling force was carried out by peeling the sample film at 180° under the condition of a tensile speed of 0.3 m / min using "Intesco Model 2001 Type" manufactured by Intesco Co., Ltd.

[0228] (15) Measurement of the surface free energy of the resin layer In a measurement atmosphere of 23°C and 50% RH, using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., trade name "DMo-501"), droplets of ion-exchanged water and diiodomethane were formed on the resin layer of the sample film, and the contact angle was measured. The contact angle was measured 60 seconds after each liquid was dropped onto the laminated polyester film. Regarding the contact angle data of ion-exchanged water and diiodomethane obtained by this method, using the surface tension component values of each solvent (Table 1), the surface free energy of the antireflection layer surface was calculated by the Owens-Wendt theoretical formula.

[0229]

Table 1

[0230] (16) Measurement of the elastic modulus of resin layer (A) Using a nanoindenter (TI 950 TriboIndenter) from Hysitron, the elastic modulus of resin layer (A) was measured at a point with a penetration depth of 50 nm at room temperature (25°C).

[0231] (17) Measurement of the elastic modulus of the adhesive layer Using a nanoindenter (TI 950 TriboIndenter) from Hysitron, with a conical indenter (spherical, radius of curvature: 10 μm), the elastic modulus of the adhesive layer was measured at a point with a penetration depth of 500 nm at room temperature (25°C).

[0232] (18) Adhesive peel strength On the release layer surface of the sample film, the adhesive composition described in Table 8 was applied so that the film thickness in the wet state was 2 mil, and heat-treated at 150°C for 3 minutes to cure and form an adhesive layer (thickness (after drying): 20 μm).

[0233] Subsequently, another release film was laminated on the adhesive layer to obtain a film laminate composed of a sample film / adhesive layer / another release film. As the other release film, the release films prepared in Comparative Examples 1 to 4 described below were used. In the obtained film laminate, the peel strength when peeling the sample film from the adhesive layer was measured. The peel strength was measured at a peel angle of 180° under the condition of a tensile speed of 0.3 m / min using "Intesco Model 2001" manufactured by Intesco Co., Ltd.

[0234] The polyesters used in the examples and comparative examples were prepared as follows.

[0235] <Manufacturing method of polyester (A)> Using 100 parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol as starting materials, 0.09 part by mass of magnesium acetate tetrahydrate as a catalyst was placed in a reactor. The reaction start temperature was set at 150°C, and the reaction temperature was gradually increased as methanol was distilled off. After 3 hours, the temperature was set at 230°C. After 4 hours, the transesterification reaction was substantially completed. After adding 0.04 part by mass of ethyl acid phosphate to this reaction mixture, 0.04 part by mass of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually increased from 230°C to 280°C. On the other hand, the pressure was gradually reduced from normal pressure and finally set at 0.3 mmHg. After the start of the reaction, the reaction was stopped at the point corresponding to an intrinsic viscosity of 0.65 based on the change in the stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure to obtain polyester (A) with an intrinsic viscosity of 0.65.

[0236] <Manufacturing method of polyester (B)> In the manufacturing method of polyester (A), after adding 0.04 part by mass of ethyl acid phosphate, 0.2 part by mass of silica particles dispersed in ethylene glycol with an average particle diameter of 2.3 μm and 0.04 part by mass of antimony trioxide were added, and polyester (B) was obtained in the same manner as the manufacturing method of polyester (A) except that the polycondensation reaction was stopped at the point corresponding to an intrinsic viscosity of 0.65. The obtained polyester (B) had an intrinsic viscosity of 0.65.

[0237] Example 1-1 A mixed raw material obtained by mixing polyesters (A) and (B) at a ratio of 90% by mass and 10% by mass, respectively, was used as the raw material for the outermost layer (surface layer), and polyester (A) was used as the raw material for the intermediate layer. Each was supplied to two extruders, melted at 290 °C each, and then co-extruded and cooled and solidified on a cooling roll set at 25 °C in a layer structure of two types and three layers (surface layer / intermediate layer / surface layer = 1:18:1 discharge amount) to obtain an unstretched sheet. Next, using the roll peripheral speed difference, it was longitudinally stretched 3.4 times at a film temperature of 85 °C, and then on one side of the longitudinally stretched film, Coating solution 1 of resin layer (B) shown in Table 4 was applied, and on the other side, the following undercoat layer composition was applied respectively, guided to a tenter, stretched 4.5 times at 120 °C in the transverse direction, heat-treated at 225 °C, and then relaxed 2% in the transverse direction to obtain a biaxially stretched polyester film having a thickness of 50 μm with a resin layer (B) film thickness (after drying) of 0.05 μm and an undercoat layer film thickness (after drying) of 0.05 μm each.

[0238] Subsequently, on the undercoat layer side of the obtained polyester film, as resin layer (A), Coating solution 1 of resin layer (A) shown in Table 3 was applied by bar coating method using a No. 4 bar so that the thickness of the coating amount (after drying) became 1.0 μm, and then dried at 150 °C for 30 seconds to obtain a release film.

[0239] Examples 1-2 to 1-12: Release films were obtained in the same manner as in Example 1-1 except that Coating solutions 2 to 12 of resin layer (B) shown in Table 4 were applied on one side of the longitudinally stretched film.

[0240] As shown in Table 4, the obtained release film had a thin resin layer (A) with an elastic modulus of 500 MPa or less. On the other hand, since the resin layer (B) contained a non-silicone-based release agent, while realizing ultra-light release with a peel force (normal peel force) of 5 g / 25 mm or less, the re-peel rate after pressing was 100% or less, achieving both anti-blocking properties. Also, it had good substrate adhesion and low migration.

[0241] Examples 1-13 to 1-28 A mixed raw material in which polyesters (A) and (B) are mixed at a ratio of 97% by mass and 3% by mass respectively is used as the raw material for the outermost layer (surface layer), and polyester (A) is used as the raw material for the intermediate layer. They are supplied to two extruders respectively, melted at 290 °C each, and then co-extruded and cooled and solidified on a cooling roll set at 25 °C in a layer structure of two types and three layers (surface layer / intermediate layer / surface layer = 1:18:1 discharge amount) to obtain an unstretched sheet. Next, using the roll peripheral speed difference, it is longitudinally stretched 3.4 times at a film temperature of 85 °C, and then, on one side of the longitudinally stretched film, the coating solution of resin layer (B) shown in Table 4 and on the other side, the following undercoat layer composition are respectively coated, led to a tenter, stretched 4.5 times at 120 °C in the transverse direction, heat-treated at 225 °C, and then relaxed 2% in the transverse direction to obtain a biaxially stretched polyester film with a thickness of 50 μm having a resin layer (B) film thickness (after drying) of 0.05 μm and an undercoat layer film thickness (after drying) of 0.05 μm each.

[0242] Subsequently, on the undercoat layer surface of the obtained polyester film, as resin layer (A), coating solution 1 of resin layer (A) shown in Table 3 was applied by bar coating method using a No. 4 bar so that the thickness of the coating amount (after drying) became 1.0 μm, and then dried at 150 °C for 30 seconds to obtain a release film.

[0243] As shown in Table 5, the obtained release film has a thin resin layer (A) and an elastic modulus of 500 MPa or less. On the other hand, since the resin layer (B) contains a non-silicone-based release agent, while realizing ultra-light release with a peel force (normal peel force) of 5 g / 25 mm or less, it also achieved both a post-press re-peel rate of 100% or less and anti-blocking property. Also, it had good substrate adhesion and low migration property.

[0244] Comparative Example 1-1 A release film was obtained in the same manner as in Example 1-1 except that the resin layer (B) and the undercoat layer were not provided on the longitudinally stretched film.

[0245] Comparative Example 1-2 A release film was obtained in the same manner as in Example 1-1 except that the resin layer (B) was not provided on the longitudinally stretched film.

[0246] As shown in Table 5, the obtained release films of Comparative Examples 1-1 to 1-2 had a high re-peeling rate after pressing and were prone to blocking because the resin layer (B) containing a non-silicone release agent did not exist.

[0247] Comparative Example 1-3 In Example 1-1, except that the coating solution 13 containing no non-silicone release agent was used for the resin layer (B) composition, the release film was produced in the same manner as in Example 1 to obtain a release film. As shown in Table 5, the obtained release film had a high re-peeling rate after pressing and was prone to blocking because the resin layer (B) did not contain a non-silicone release agent.

[0248] Comparative Example 1-4 In Example 1-1, except that the coating solution 2 for the resin layer (A) was changed, the release film was produced in the same manner as in Example 1 to obtain a release film. As shown in Table 5, the obtained release film had a thin resin layer (A) and a high elastic modulus, so the release force (normal release force) was about three times higher than that of Examples 1-1 to 1-12, and ultra-light peeling could not be achieved. Also, the adhesion to the substrate was poor.

[0249] Reference Example 1 In Example 1, except that the coating solution 3 (particle content: 0.19% by mass) for the resin layer (A) was changed, the release film was produced in the same manner as in Example 1 to obtain a release film. As shown in Table 5, due to the presence of particles, the resin layer (A) became brittle, so the adhesion to the substrate was poor, and the migration property was relatively high due to the shedding of the particles. Also, the re-peeling rate after pressing was high and the occurrence of blocking was a concern.

[0250] Examples of the compound constituting the resin layer (A) are as follows. a1: A curable silicone resin (a silicone resin with vinyl groups introduced into the side chains and / or terminals of the main chain composed of siloxane bonds, number average molecular weight: 10,600, viscosity at 25 °C when adjusted to 15% by mass with n-heptane solvent dilution: 1.7 m cps) a2: A mixture containing a curable silicone resin (a silicone resin with vinyl groups introduced into the side chains and / or terminals of the main chain composed of siloxane bonds, number average molecular weight: 364,000) and a silicone crosslinking agent (a silicone resin with Si-H groups introduced into the side chains and / or terminals of the main chain composed of siloxane bonds) (viscosity at 25 °C when adjusted to 15% by mass with n-heptane solvent dilution: 410 m cps)

[0251] The content ratio (mol%) of each functional group in the curable silicone resin is as follows.

[0252]

Table 2

[0253] b1: A silicone crosslinking agent (CL750: manufactured by Momentive Performance Materials) c1: An addition-type platinum catalyst (CM678: manufactured by Momentive Performance Materials) c2: An addition-type platinum catalyst (PL-50T: manufactured by Shin-Etsu Chemical Co., Ltd.) d1: Particles (Tospearl 120: manufactured by Momentive Performance Materials)

[0254] The coating solution constituting the resin layer (A) is as follows.

[0255]

Table 3

[0256] Examples of the compounds constituting the resin layer (B) and the undercoat layer are as follows.

[0257] (Release agent) AI: Compound Containing Long-Chain Alkyl Group 200 parts of xylene and 600 parts of octadecyl isocyanate were added to a four-necked flask and heated with stirring. Starting from the time when the xylene began to reflux, 100 parts of polyvinyl alcohol with an average degree of polymerization of 500 and a saponification degree of 88 mol% were added little by little at 10-minute intervals over about 2 hours. After the addition of polyvinyl alcohol was completed, reflux was continued for another 2 hours to terminate the reaction. After the reaction mixture was cooled to about 80 °C, it was added to methanol. At this time, the reaction product precipitated as a white precipitate. Therefore, this precipitate was filtered off, 140 parts of xylene were added, and after heating and completely dissolving, methanol was added again to precipitate. This operation was repeated several times, and then the precipitate was washed with methanol, dried, and pulverized to obtain the product. AII: Wax 300 g of oxidized polyethylene wax with a melting point of 105 °C, an acid value of 16 mg KOH / g, a density of 0.93 g / mL, and an average molecular weight of 5000, 650 g of ion-exchanged water, 50 g of decaglycerin monooleate surfactant, and 10 g of 48% potassium hydroxide aqueous solution were added to an emulsifying equipment with an internal volume of 1.5 L equipped with a stirrer, a thermometer, and a temperature controller. After replacing with nitrogen, it was sealed and stirred at high speed at 150 °C for 1 hour and then cooled to 130 °C. The wax emulsion was passed through a high-pressure homogenizer at 400 atmospheres and cooled to 40 °C.

[0258] (Antistatic Agent) BI: A conductive agent composed of polyethylene dioxythiophene and polystyrene sulfonic acid (Orgacon ICP1010 manufactured by Agfa-Gevaert) neutralized with concentrated ammonia water to a pH of 9. Non-volatile component: 1.2% by mass, solvent: water

[0259] (Polyhydroxy Compound) CI: Polyglycerin with an average n = 4 in the formula (9) CII: A compound in which an average of 4 molecules of polyethylene oxide are added to the polyglycerin skeleton with an average n = 2 in the formula (9).

[0260] (Binder) DI: A water dispersion of a polyester resin copolymerized 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%) DII: A urethane resin water dispersion polymerized with the following composition When the polyester polyol composed of 282 parts by mass of terephthalic acid, 282 parts by mass of isophthalic acid, 62 parts by mass of ethylene glycol, and 250 parts by mass of neopentyl glycol was used as (C1a), (C1a) 876 parts by mass, 244 parts by mass of tolylene diisocyanate, 81 parts by mass of ethylene glycol, and 67 parts by mass of dimethylolpropionic acid were neutralized with ammonia and dispersed in water (concentration 20%, viscosity at 25 °C: 50 mPa·s)

[0261] (Crosslinking agent) EI: Hexamethoxymethylmelamine EII: An acrylic polymer having an oxazoline group and a polyalkylene oxide chain Epocros (amount of oxazoline group = 4.5 mmol / g, manufactured by Nippon Shokubai Co., Ltd.)

[0262] (Surfactant) FI: A nonionic surfactant having a structure with polyethylene oxide in the side chain represented by the following formula

[0263] [Chemical formula] In the above formula, m and n are integers representing the number of moles of ethylene oxide added, and here, those with an average of m + n = 10 were used.

[0264] The coating liquid constituting the resin layer (B) is as follows. Table 3 shows the amounts based on the non-volatile components.

[0265] [Table 4]

[0266] <Undercoating layer composition> The coating solution constituting the undercoating layer is as follows. (BI) / (CII) / (DII) / (FI)=10 mass% / 35 mass% / 50 mass% / 5 mass%

[0267]

Table 5

[0268] <Production method of polyester (1)> Using 100 parts by mass of dimethyl terephthalate and 55 parts by mass of ethylene glycol as starting materials, 0.04 part by mass of magnesium acetate tetrahydrate was placed in the reactor as a catalyst, the reaction start temperature was set at 150 °C, and the reaction temperature was gradually increased as methanol was distilled off, reaching 230 °C after 3 hours. After 4 hours, the transesterification reaction was substantially completed. After adding 0.02 part by mass of ethyl acid phosphate to this reaction mixture, 0.04 part by mass of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually increased from 230 °C to 280 °C. On the other hand, the pressure was gradually reduced from atmospheric pressure and finally set at 0.3 mmHg. After the start of the reaction, the reaction was stopped at the point corresponding to an intrinsic viscosity of 0.59 dl / g based on the change in the stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure to obtain polyester (1) with an intrinsic viscosity of 0.59 dl / g.

[0269] <Production method of polyester (2)> Using 100 parts by mass of dimethyl terephthalate and 45 parts by mass of ethylene glycol as starting materials, 0.06 part by mass of magnesium acetate tetrahydrate as a catalyst was placed in a reactor. The reaction start temperature was set at 150 °C, and the reaction temperature was gradually increased as methanol was distilled off, reaching 230 °C after 3 hours. After 4 hours, the transesterification reaction was substantially completed. After adding 0.03 part by mass of ethyl acid phosphate to this reaction mixture, 0.3 part by mass of silica particles with an average particle size of 2.7 μm dispersed in ethylene glycol and 0.03 part by mass of antimony trioxide were added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually increased from 230 °C to 280 °C. On the other hand, the pressure was gradually reduced from normal pressure and finally set at 0.3 mmHg. After the start of the reaction, when the intrinsic viscosity reached 0.59 dl / g according to the change in the stirring power of the reaction tank, the reaction was stopped, and the polymer was discharged under nitrogen pressure to obtain a polyester (2) with an intrinsic viscosity of 0.59 dl / g.

[0270] <Method for producing polyester (3)> In polyester (2), except that 10 parts by mass of organic particles (styrene-divinylbenzene: styrene-based resin) with an average particle size of 4.5 μm were added instead of the silica particles, it was produced in the same manner as polyester (2) to obtain a polyester (3) with an intrinsic viscosity of 0.60 dl / g.

[0271] <Method for producing polyester film> [PET-A] A layer is made by blending polyester (1) and polyester (2) at a mass ratio of 80 / 20, and B layer uses only polyester (1) as the raw material. Polyester (1) and polyester (3) blended at a mass ratio of 95.5 / 4.5 are respectively supplied to a C layer extruder, heated and melted at 285 °C, and co-extruded with a three-layer structure of three layers (A (A layer) / B (B layer) / C (C layer)) with A layer and C layer as the outermost layer (surface layer) and B layer as the intermediate layer, and the thickness composition ratio is A / B / C = 5 / 90 / 5 under the extrusion conditions. While closely adhering to a mirror cooling drum with a surface temperature of 40 - 50 °C, it is cooled and solidified to produce an unstretched polyethylene terephthalate film. This film is stretched 3.0 times in the longitudinal direction while passing through a heating roll group at 85 °C to obtain a uniaxially oriented film. For this uniaxially stretched film, the following cured resin layer composition is applied to both sides, then the film is guided to a tenter stretching machine, stretched 4.1 times in the width direction at 100 °C, further heat-treated at 235 °C, and then a relaxation treatment of 2% in the width direction is performed to obtain a biaxially oriented polyester film with a thickness of 50 μm and a cured resin layer with a film thickness (after drying) of 0.05 μm on both sides.

[0272] (Cured resin layer composition) (A): Thiophene-based antistatic agent A conductive agent composed of polyethylene dioxythiophene and polystyrene sulfonic acid, "Orgacon ICP1010" manufactured by Agfa-Gevaert, neutralized with concentrated ammonia water to pH = 9. (B) Polyhydroxy compound Polyglycerin with an average degree of polymerization of 4 (C) An aqueous dispersion of a polyester resin having a condensed polycyclic structure copolymerized 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%) A / B / C = 7 / 10 / 83 (mass%)

[0273] <Release layer composition> a1: A curable silicone resin (a silicone resin with vinyl groups introduced to the side chains and / or terminals of the main chain composed of siloxane bonds, number average molecular weight: 10,600, viscosity at 25 °C when adjusted to 15% by mass with n-heptane solvent dilution: 1.7 m cps)

[0274] (Composition analysis of curable silicone resin) The composition analysis of the curable silicone resins used in the examples and comparative examples was carried out using 400 MHz-NMR (Bruker Avance400M), and the results are shown in Table 1. 1 For 1H-NMR measurement, CDCl3 was used as the solvent, and the measurement was carried out at a temperature of 30 °C with the peak derived from the methyl group of dimethylsiloxane as the chemical shift reference. Table 1 below shows the content ratios (mol%) of each functional group in the curable silicone resin.

[0275]

Table 6

[0276] b1: Crosslinking agent (CL750: manufactured by Momentive Performance Materials) c1: Addition-type platinum catalyst (CM678: manufactured by Momentive Performance Materials) e1: Light release agent (methylphenyl silicone oil, Mw: less than 10,000, phenyl group content ratio; DM:MP = 91:9 (mol%)) e2: Light release agent (methylphenyl silicone oil, Mw: 21,000, phenyl group content ratio; DM:MP = 91:9 (mol%)) e3: Light release agent (methylphenyl silicone oil, Mw: 71,000, phenyl group content ratio; DM:MP = 90:10 (mol%)) e4: Light release agent BY24-850 (manufactured by Toray Dow) (polydimethylsiloxane, Mw: 100,000 or more, phenyl group content ratio; DM:MP = 100:0 (mol%))

[0277] [Example 2-1] On the flat surface of the A layer side of PET-A, the following release layer composition was applied so that the thickness after drying was 1 g / m 2 and then dried at 150°C for 30 seconds to obtain a release film (sample film).

[0278] (Release layer composition) Main agent: a1; 100 parts by mass Crosslinking agent: b1; 3 parts by mass Catalyst: c1; 3 parts by mass Light release agent: e1; 1 part by mass Solvent: Toluene; 1000 parts by mass MEK; 9000 parts by mass

[0279] [Example 2-2 to 2-5] Regarding the release layer composition, except that the type and addition amount of the light release agent were changed as shown in Table 7 below, it was produced in the same manner as in Example 2-1 to obtain a film laminate.

[0280] [Comparative Example 2-1] In the release layer composition, except that no light release agent was added, it was produced in the same manner as in Example 1 to obtain a film laminate.

[0281] [Comparative Example 2-2] In Example 1, except that the composition of the release layer was changed to the following release layer composition, it was produced in the same manner as in Example 1 to obtain a release film (sample film).

[0282] (Release layer composition) Main agent: a1; 100 parts by mass Crosslinking agent: b1; 3 parts by mass Catalyst: c1; 3 parts by mass Light release agent: e4; 1 part by mass Solvent: Toluene; 1000 parts by mass MEK; 9000 parts by mass

[0283]

Table 7

[0284] From the results of this example, by making the release layer containing a curable silicone resin relatively thick, using a specific-configuration light release agent in combination, and setting the elastic modulus to 500 MPa or less, while making the maximum cross-sectional height (Rt) of the anti-release surface within a predetermined range, it was confirmed that a release film with not only a low release force, low migration property, and low blocking property, but also good adhesion to the substrate could be obtained. In addition, when comparing Comparative Example 1 with each example in terms of the release force (normal release force) using an adhesive tape, in the lightest type, it was possible to achieve light release to about 60% of Comparative Example 1, realizing ultra-light release. On the other hand, Comparative Example 1 was at the conventional product level (light release type), and it was found that the release force with respect to the adhesive layer was large. In Comparative Example 2, since a light release agent with a large molecular weight was contained in the release layer, the result was poor in the light release effect.

[0285] Example 3-1 Regarding the release layer used in Example 1-1, the releasability was evaluated using the adhesives described below. The results are shown in Table 8. Adhesive A: 2EHA / BA / HEA = 36 / 59 / 5 mass% (elastic modulus: 2.9 MPa, Tg: -59.0 °C) Adhesive B: 2EHA / HEA / AAc = 92.8 / 7 / 0.2 mass% (elastic modulus: 2.7 MPa, Tg: -66.7 °C) 2EHA; 2-ethylhexyl acrylate BA; butyl acrylate HEA; hydroxyethyl acrylate AAc; acrylic acid

[0286] Example 3-2 In Example 3-1, the evaluation was carried out in the same manner as in Example 3-1, except that the release layer used in Example 2-1 was used as the release layer. The results are shown in Table 8.

[0287]

Table 8

[0288] It was found that all the resin layers used in the examples were more easily peelable than those in the reference examples (conventional technology).

Industrial Applicability

[0289] According to the release film of the present invention, it is possible to provide a release film that realizes ultra-light peelability and is less likely to change the peeling characteristics of the release layer due to blocking, and its industrial value is high. Further, the release film of the present invention and the film laminate including the release film have the characteristics of achieving both ultra-light peelability and blocking resistance, and thus are suitable for applications that dislike changes in the peeling characteristics of the release layer and deterioration of the appearance of the surface of the resin layer (A). For example, for the production of capacitive touch panels, various applications for bonding via an adhesive layer, optical members (polarizing plates, retardation plates, prism sheets, conductive films, resin films, glass substrates, etc.) used in liquid crystal displays, for the production of organic electroluminescence components, etc., in addition to the production of various display components, it is suitably used for various adhesive layer protection applications. Among them, in particular, it can also be applied to foldable display applications with a soft adhesive layer that easily follows deformation due to folding.

Claims

1. A release film having a resin layer (A) on one surface of a base film and a resin layer (B) on the other surface, wherein the resin layer (A) contains a silicone resin-based release agent and has a thickness of 0.2 to 2.0 μm, and the resin layer (B) contains a non-silicone resin-based release agent.

2. A release film having a resin layer (A) provided on at least one side of a base film, wherein the resin layer (A) is a cured product of a resin composition containing a curable silicone resin and a light release agent, the light release agent having a dimethylsiloxane skeleton (DM) represented by the following formula (I) and a methylphenylsiloxane skeleton (MP) represented by the following formula (II), and having a thickness of 0.2 to 1.5 μm. 【Chemical 1】 【Chemical 2】

3. The release film according to claim 2, wherein the maximum cross-sectional height (Rt) of the film surface on the side opposite to the surface on which the resin layer (A) is provided is 2.0 μm or less.

4. The release film according to claim 2 or 3, wherein the surface on the side opposite to the surface on which the resin layer (A) of the base film is provided is provided with a polyester layer containing 0.4 to 1.0% by mass of particles having an average particle diameter of 1 to 6 μm.

5. The release film according to any one of claims 2 to 4, wherein the mass average molecular weight of the light release agent is 10,000 or more and 100,000 or less.

6. The release film according to any one of claims 1 to 5, wherein the elastic modulus at 25°C measured using a nanoindenter device for the resin layer (A) is 500 MPa or less.

7. The release film according to claim 1 or 6, wherein the non-silicone resin-based release agent is at least one selected from the group consisting of wax, a long-chain alkyl group-containing compound, and a fluorine compound.

8. The release film according to claim 1, 6 or 7, wherein the content of the release agent in the non-volatile components of the resin layer (B) is 10 to 70% by mass.

9. The release film according to any one of claims 1 and 6 to 8, wherein the resin layer (B) substantially does not contain particles.

10. The release film according to any one of claims 1 to 9, wherein the normal release force of the resin layer (A) measured by the following evaluation method is 5 g / 25 mm or less. <Evaluation Method> After sticking an acrylic adhesive tape (“No. 7475” manufactured by Tesa) on the resin layer (A) surface of the release film, it is cut into a size of 25 mm × 150 mm and left at room temperature for 1 hour. The release force is measured by peeling at 180° under the condition of a tensile speed of 0.3 m / min.

11. The release film according to any one of Claims 1 and 6 to 10, comprising an undercoat layer between at least one of the resin layer (A) or the resin layer (B) and the base film.

12. The release film according to Claim 11, wherein the undercoat layer is an antistatic layer.

13. The release film according to Claim 11 or 12, wherein the undercoat layer contains the following compounds (A) to (C). (A) A polymer doped with another anionic compound in a compound composed of thiophene or a thiophene derivative, or a polymer having an anionic group in a compound composed of thiophene or a thiophene derivative and self-doped (B) A polyhydroxy compound (C) One or more compounds selected from the group consisting of a polyurethane resin, a polyester resin, and an acrylic resin

14. The surface resistivity of at least one surface of the resin layer (A) or the resin layer (B) is 1 × 10 １２ Ω / sq or less. The release film according to any one of claims 1 and 6 to 13.

15. The release film according to any one of Claims 1 to 14, wherein the base film is a polyester film.

16. The release film according to Claim 15, wherein the polyester film has a three-layer structure.

17. The release film according to any one of Claims 1 to 16, wherein the post-press re-peeling rate of the resin layer (A) evaluated by the following method is 100% or less. <Evaluation method> After sticking an acrylic adhesive tape ("No. 7475" manufactured by Tesa) on the surface of the resin layer (A), cut it into a size of 25 mm × 150 mm and leave it at room temperature for 1 hour. The peeling force peeled at 180° under the condition of a tensile speed of 0.3 m / min is defined as (F1). Next, laminate it so as to contact the surface of the resin layer (A), and perform a press treatment at a temperature of 40°C, a humidity of 90% RH, and a load of 1 MPa for 20 hours. After sticking an acrylic adhesive tape ("No. 7475" manufactured by Tesa) on the surface of the resin layer (A) after the treatment, cut it into a size of 25 mm × 150 mm and leave it at room temperature for 1 hour. The peeling force peeled at 180° under the condition of a tensile speed of 0.3 m / min is defined as (F2). The post-press re-peeling rate is obtained by the following formula. Post-press re-peeling rate (%) = (F2 - F1) / F1 × 100

18. The release film according to any one of Claims 1 to 17, wherein the center line average roughness (Ra(A)) of the surface of the resin layer (A) is 30 nm or less.

19. The release film according to Claim 1 or any one of Claims 6 to 18, wherein the center line average roughness (Ra(B)) of the surface of the resin layer (B) is 60 nm or less.

20. A pressure-sensitive adhesive sheet comprising the release film according to any one of claims 1 to 19 and another release film via a pressure-sensitive adhesive layer.

21. The pressure-sensitive adhesive sheet according to claim 20, wherein the pressure-sensitive adhesive layer is formed from an acrylic pressure-sensitive adhesive composition.

22. The pressure-sensitive adhesive sheet according to claim 20 or 21, wherein the elastic modulus (25 ° C) of the pressure-sensitive adhesive layer is 6.0 MPa or less.

23. The pressure-sensitive adhesive sheet according to any one of claims 20 to 22, wherein the pressure-sensitive adhesive layer contains 2-ethylhexyl acrylate and / or butyl acrylate.

24. The pressure-sensitive adhesive sheet according to any one of claims 20 to 23, which is for an optical transparent pressure-sensitive adhesive sheet.

25. The release film according to any one of claims 1 to 19, which is for a display.

26. The release film according to any one of claims 1 to 19, which is for a foldable display.

27. A method of using a pressure-sensitive adhesive sheet according to any one of claims 20 to 23, wherein after peeling off the other release film, the surface of the pressure-sensitive adhesive layer that is exposed is bonded to an optical member.

28. The method of using a pressure-sensitive adhesive sheet according to claim 27, wherein the optical member is a polarizing plate or a touch sensor.

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