Release film and laminated film

Abstract

To provide a release film capable of exhibiting good releasability even in a high temperature environment.SOLUTION: There is provided a release film having a resin layer A on one surface A of a base material film, wherein the resin layer A contains a non-silicone-based release agent and a cross-linking agent, and when the peeling force between the resin layer A and an acrylic adhesive tape (No. 31B produced by Nitto Denko Co., Ltd.) after the acrylic adhesive tape is pressed onto the resin layer A and heat-treated at 100°C for 1 hour is defined as F2 and the peeling force between the resin layer A and the acrylic adhesive tape (No. 31B produced by Nitto Denko Co., Ltd.) under an environment of 25°C without heat treatment after the acrylic adhesive tape is pressed onto the resin layer A is defined as F1, the value of F2 / F1 is 15 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a release film and a laminated film.

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 excellent in cost performance, so they are used in various applications. For example, they are used for polarizing plates for liquid crystal displays (LCDs), for manufacturing retardation plates, for manufacturing organic electroluminescence (organic EL) components, etc., for manufacturing various display components, and for various optical applications.

[0003] The uses of release films include those for transfer such as simultaneous transfer during molding, for manufacturing flexible printed wiring boards, and for process papers for manufacturing plastic sheets. During various manufacturing processes, release films are used. In these manufacturing processes, the release film may be exposed to a high-temperature atmosphere or a high pressing pressure may be applied to the release film. For example, when manufacturing a printed wiring board, when a release film is used for forming an insulating layer, especially when dealing with the formation of an insulating layer that requires a high level of embedability, the adhesiveness of the insulating layer itself tends to increase. In addition, since there is a lamination process under a high-temperature atmosphere, high-temperature heat and pressing pressure are applied to the release film (Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, high-temperature heat and press pressure may be applied to the release film used in various manufacturing processes. However, when a conventional release film is used, there is a problem that the releasability of the film decreases and it cannot be smoothly peeled off from the adherend. Therefore, there is a need for a release film that has excellent heat resistance and maintains good releasability even after passing through a hot press process. In addition, in the hot press process of various manufacturing processes, a hot press process under vacuum may be adopted from the viewpoint of improving productivity. In this case, the release film is also required to have a performance that contributes to quickly creating a vacuum state.

[0006] For this reason, an object of the present invention is to provide a release film that can exhibit good releasability even in a high-temperature environment. Another object of the present invention is to provide a release film that can quickly create a vacuum state even when the hot press treatment is performed under vacuum.

Means for Solving the Problems

[0007] In view of the above circumstances, the present inventors have conducted intensive studies and as a result, have found that the above problems can be easily solved by using a release film having a specific configuration, and have completed the present invention. That is, the present invention provides the following [1] to

[20] . [1] A resin layer A is provided on one surface A of a base film, The resin layer A contains a non-silicone-based release agent and a crosslinking agent, After a acrylic adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded onto the resin layer A and heat-treated at 100°C for 1 hour, the peel strength between the resin layer A and the acrylic adhesive tape is defined as F2, When a acrylic adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded onto the resin layer A and the peel strength between the resin layer A and the acrylic adhesive tape in an environment at 25°C is defined as F1, A release film with an F2 / F1 value of 15 or less. [2] The release film according to [1], wherein the peel strength (F2) is 2700 mN / cm or less. [3] The release film according to [1] or [2], wherein the peel strength (F1) is 1600 mN / cm or less. [4] In the release film, when the surface located on the side opposite to the resin layer A is defined as surface C, the release film according to any one of [1] to [3], which satisfies the following conditions (1) and (2); (1) The average surface roughness (Sa) of the resin layer A surface is 1 to 10 nm; (2) The maximum height (Sz) of surface C is 400 nm or more. [5] The release film according to any one of [1] to [4], wherein the base film is a polyester film. [6] The release film according to [5], wherein the polyester film has a three-layer structure. [7] The release film according to [6], wherein the intermediate layer of the polyester film contains 50% by mass or more of recycled polyester raw material. [8] The polyester film has a structure of a surface layer A, an intermediate layer B, and a surface layer C in this order from the side where the resin layer A is laminated, The release film according to [6] or [7], wherein the surface layer C contains first particles with a particle size of 0.1 to 0.5 μm and second particles with a particle size of 0.6 to 1.5 μm. [9] The release film according to [8], wherein the maximum value of the difference in particle size between the first particles and the second particles is 0.1 μm or more.

[10] The release film according to any one of [1] to [9], wherein the non-silicone release agent is at least one selected from long-chain alkyl compounds and waxes.

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

[10] , wherein the crosslinking agent is at least one selected from the group consisting of melamine compounds, oxazoline compounds, and isocyanate compounds.

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

[11] , wherein the non-silicone release agent is a long-chain alkyl compound and the crosslinking agent is a blocked isocyanate.

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

[12] , wherein the crosslinking agent is an active methylene block isocyanate compound.

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

[13] , further comprising a resin layer C on the side opposite to the resin layer A.

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

[14] , which is for thermocompression molding.

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

[15] , which is for printed wiring boards.

[17] A laminated film comprising a resin layer B further on the resin layer A of the release film according to any one of [1] to

[16] .

[18] The laminated film according to

[17] , further comprising a protective film on the resin layer B.

[19] The laminated film according to

[17] or

[18] , which is for thermocompression molding.

[20] The laminated film according to any one of

[17] to

[19] , which is for printed wiring boards. [Advantages of the Invention]

[0008] According to the present invention, a release film capable of exhibiting good releasability even in a high-temperature environment can be obtained. Further, according to the present invention, a release film capable of quickly creating a vacuum state even when a thermocompression treatment is performed under vacuum can be obtained. [Brief Description of the Drawings]

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0010] Next, an example of an embodiment of the present invention will be described. 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. In the present specification, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it means "X or more and Y or less", and also includes the meaning of "preferably larger than X" or "preferably smaller than Y". Further, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it also includes the intention of "preferably larger than X" or "preferably less than Y". In the following description, "film" and "sheet" are not clearly distinguished, and when referred to as "film", it includes "sheet", and when referred to as "sheet", it includes "film".

[0011] [Release Film] The present embodiment relates to a release film having a resin layer A on one surface A of a base film, and the resin layer A contains a non-silicone release agent and a cross-linking agent (hereinafter, also referred to as "the present release film"). Here, an acrylic adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded onto the resin layer A, and after heat treatment at 100° C. for 1 hour, the peel force between the resin layer A and the acrylic adhesive tape is defined as F2, and an acrylic adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded onto the resin layer A, and in an environment of 25° C., when the peel force between the resin layer A and the acrylic adhesive tape is defined as F1, the value of F2 / F1 is 15 or less. The value of F2 / F1 is preferably 14 or less, more preferably 13 or less, and even more preferably 12 or less. The lower limit value of F2 / F1 is not particularly limited, but for example, it is preferably 1 or more.

[0012] When measuring the peeling force (F1), an adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded to the surface of the resin layer A of the release film in one round trip with a 2 kg rubber roller, left standing at room temperature (25 °C) for 1 hour, and then the peeling force is measured. The peeling force (F1) is the peeling force of the release film before heat treatment. When measuring, "Ezgraph" manufactured by Shimadzu Corporation is used, and 180° peeling is performed under the condition of a tensile speed of 300 mm / min. The peeling force (F1) is preferably 1600 mN / cm or less, more preferably 1000 mN / cm or less, and even more preferably 500 mN / cm or less. Also, the peeling force (F1) is preferably 50 mN / cm or more. By setting the peeling force (F1) within the above range, the peelability of the resin layer A can be more effectively enhanced.

[0013] When measuring the peeling force (F2), an adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded to the surface of the resin layer A of the release film in one round trip with a 2 kg rubber roller, heated in an oven at 100 °C for 1 hour, then left standing at room temperature (25 °C) for 1 hour, and then the peeling force is measured. When measuring, "Ezgraph" manufactured by Shimadzu Corporation is used, and 180° peeling is performed under the condition of a tensile speed of 300 mm / min. The peeling force (F2) is preferably 2700 mN / cm or less, more preferably 2000 mN / cm or less. Also, the peeling force (F2) is preferably 100 mN / cm or more. By setting the peeling force (F2) within the above range, the peelability of the resin layer A after heat treatment can be more effectively enhanced.

[0014] In order to make the value of F2 / F1 fall within a predetermined range, for example, the type and content of the release agent and crosslinking agent contained in the resin layer A can be adjusted, or the manufacturing process can be optimized. Preferred combinations of the resin layer A include combinations of a long-chain alkyl compound, a melamine compound, and an isocyanate compound; combinations of a long-chain alkyl compound, an acrylic resin, a melamine compound, and an isocyanate compound; combinations of a long-chain alkyl compound, a polyester resin, a melamine compound, and an isocyanate compound; combinations of a long-chain alkyl compound, an acrylic resin, an antistatic agent, a melamine compound, and an isocyanate compound; and combinations of a wax, a polyester resin, and a melamine compound. It is also preferable that the blending ratio of each component be within the range described below.

[0015] By having the above configuration, this release film can exhibit excellent releasability even in a high-temperature environment. Therefore, this release film is preferably used as a process release film in various manufacturing processes. Note that this embodiment may relate to a film roll formed by winding this release film in a roll shape.

[0016] (Surface characteristics) As shown in FIG. 1, this release film 100 has a base film 10 and a resin layer A 20. In this embodiment, the surface located on the side opposite to the side where the resin layer A 20 is laminated is defined as surface C. In this case, it is preferable that this release film satisfies at least one of the following conditions (1) and (2), and it is particularly preferable that both conditions (1) and (2) are satisfied. Note that in this specification, surface C is the surface of the release film located on the side opposite to the resin layer A and is the exposed surface. In the case of FIG. 1, surface C is the exposed surface of the base film 10, but when a resin layer C 30 is provided as shown in FIG. 3, surface C becomes the exposed surface of the resin layer C 30. (1) The average surface roughness (Sa) of the resin layer A surface is 1 to 10 nm. (2) The maximum height (Sz) of surface C is 400 nm or more.

[0017] In this release film, by setting the average surface roughness (Sa) of the surface of resin layer A to 1 to 10 nm, the fine unevenness on the surface of resin layer A is controlled, and high smoothness is achieved. Therefore, this release film can exhibit excellent scratch resistance and releasability. Further, by setting the average surface roughness (Sa) of the surface of resin layer A to 1 to 10 nm, for example, it is preferably used for forming an insulating layer of a printed wiring board. In this case, a highly smooth insulating layer can be formed.

[0018] The average surface roughness (Sa) of the surface of resin layer A is preferably 1 to 10 nm, more preferably 2 to 8 nm, and even more preferably 2 to 6 nm. By setting the average surface roughness (Sa) of the surface of resin layer A to be equal to or less than the above upper limit value, the smoothness of the surface of resin layer A can be more effectively enhanced, and the releasability of this release film can be more effectively enhanced. Further, by setting the average surface roughness (Sa) of the surface of resin layer A to be equal to or greater than the above lower limit value, it is possible to suppress the extreme flattening of the surface of resin layer A, enhance the slipperiness of this release film, and as a result, it becomes difficult to get scratched, so the scratch resistance is enhanced.

[0019] The average surface roughness (Sa) is one of the surface roughness parameters (ISO 25178), which is an extension of two-dimensional Ra to three-dimensional, and is obtained by dividing the volume of the portion surrounded by the surface shape curved surface and the average plane by the measurement area, and is obtained from the following formula (1). When the surface is the XY plane and the height direction is the Z axis, assuming A: the defined area (the entire image), and Z(x, y): the height from the plane of height 0 of the image point (x, y), it is expressed as the following formula (1).

[0020]

Equation

[0021] The maximum height (Sz) of surface C is preferably 400 nm or more, more preferably 450 nm or more, and even more preferably 500 nm or more. There is no particular limitation on the upper limit of the maximum height (Sz) of surface C, but it is preferably 1000 nm or less, more preferably 900 nm or less, and even more preferably 800 nm or less. By setting the maximum height (Sz) of surface C to be equal to or greater than the above lower limit value, an appropriate uneven structure can be imparted to surface C, and this uneven structure serves as a passage for easily discharging air. As a result, it becomes possible to smoothly perform air bleeding, which contributes to quickly creating a vacuum environment, for example, in vacuum lamination processing. Further, by setting the maximum height (Sz) of surface C to be equal to or less than the above upper limit value, it becomes possible to more effectively improve the winding property of the release film.

[0022] As shown in FIG. 2, the maximum height (Sz) is one of the surface roughness parameters (ISO 25178) and is the total value of the maximum peak height (Sp) + the maximum valley depth (Sv). Note that the maximum peak height (Sp) is one of the surface roughness parameters (ISO 25178) and represents the maximum value of the height from the average surface of the surface, and is expressed as in the following formula (2).

[0023]

Equation

[0024] The maximum valley depth (Sv) is one of the surface roughness parameters (ISO 25178) and represents the absolute value of the minimum value of the depth from the average surface of the surface, and is expressed as in the following formula (3).

[0025]

Equation

[0026] The ratio Sp / Sa of the average surface roughness (Sa) to the maximum peak height (Sp) on the surface of the resin layer A of this release film is preferably 15 or less, more preferably 12 or less, and even more preferably 10 or less. By having the ratio Sp / Sa of the average surface roughness (Sa) to the maximum peak height (Sp) be 15 or less, the average surface roughness (Sa) can be adjusted to be high while keeping the maximum peak height (Sp) low, and the high smoothness of the surface of the resin layer A can be enhanced more effectively. Also, the lower limit of the ratio Sp / Sa of the average surface roughness (Sa) to the maximum peak height (Sp) is not particularly limited, but from the perspective of adjusting with a balance of high Sa and low Sp, 3 or more is preferable, and 5 or more is more preferable.

[0027] (Base film) The base film is preferably a resin film, but in this specification, the base film includes thin sheet-like materials mainly made of paper, synthetic paper, metal, etc. As the paper, for example, those with a silicone coat treatment on the surface such as high-quality paper, kraft paper, glassine paper, parchment paper, and supercalendered kraft paper can be used.

[0028] As the resin film, for example, films mainly composed of polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyimide, or polycarbonate can be used. Among the above, from the viewpoints of appearance, ease of processing, durability, heat resistance, cost, etc., the base film is preferably a polyester film (hereinafter, also referred to as "this polyester film").

[0029] The thickness of the base film is preferably 19 μm or more and 100 μm or less, more preferably 25 μm or more and 75 μm or less.

[0030] (Polyester film) This polyester film preferably serves as the base material of this release film. The polyester film may have a single-layer structure or a multilayer structure. When the polyester film has a multilayer structure, the polyester film may have a two-layer structure, a three-layer structure, etc., and may have four or more layers as long as the gist of the present invention is not deviated from, and the number of layers is not particularly limited. In addition, when the polyester film has a multilayer structure of two or more layers, a two-component three-layer or a three-component three-layer configuration is particularly preferable. In particular, the polyester film preferably has a three-layer configuration. In this case, the polyester film preferably has a layer configuration of surface layer A / intermediate layer B / surface layer C. As shown in FIG. 1, the polyester film 10 preferably has a three-layer configuration having a surface layer A12, an intermediate layer B14, and a surface layer C16 in this order. In FIG. 1, the exposed surface of the surface layer C16 is the surface C.

[0031] When the base material film has a layer configuration of surface layer A / intermediate layer B / surface layer C, the average surface roughness (Sa) of the surface of surface layer A is preferably 1 to 10 nm, more preferably 2 to 8 nm, and even more preferably 2 to 6 nm. Further, the maximum height (Sz) of the surface layer C is preferably 400 nm or more, more preferably 450 nm or more, and even more preferably 500 nm or more. There is no particular limitation on the upper limit of the maximum height (Sz) of the surface C, but it is preferably 1000 nm or less, more preferably 900 nm or less, and even more preferably 800 nm or less.

[0032] In addition, the polyester film may be an unstretched film (sheet) or a stretched film. Among them, the polyester film is preferably a stretched film stretched in a uniaxial direction or a biaxial direction. Among them, a biaxially stretched film is more preferable in terms of excellent balance of mechanical properties and flatness.

[0033] The surface roughness of the base material film can be adjusted by a combination of the thickness of the polyester layer, the average particle diameter of the particles, the addition amount, the stretching ratio, etc.

[0034] (Polyester) Examples of the polyester that is the raw material of the present polyester film include polyesters obtained by polycondensation reaction of a dicarboxylic acid component and a diol component. The polyester may be a homopolyester or a copolyester.

[0035] In this embodiment, when the dicarboxylic acid component is 100 mol%, it is preferable to use a polyester containing more than 50 mol% of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid.

[0036] Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, and 4,4'-diphenylsulfonedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid, and ester derivatives thereof.

[0037] Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-hexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxyphenyl)propane, isosorbide, and spiroglycol.

[0038] When the present polyester film is made of a homopolyester, the homopolyester 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 (PET) and polyethylene-2,6-naphthalenedicarboxylate (PEN).

[0039] On the other hand, when the above polyester is a copolyester, it is preferably a copolymer containing 30 mol% or less of a third component. The third component is a component other than the compound that is the main component of the dicarboxylic acid component constituting the polyester and the compound that is the main component of the diol component, and in polyethylene terephthalate, it is a component other than terephthalic acid and ethylene glycol. 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. Examples of the glycol component of the copolyester include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol.

[0040] Also, as the above polyester, polyethylene terephthalate in which 80 mol% or more, preferably 90 mol% or more, is an ethylene terephthalate unit, polyethylene-2,6-naphthalate in which the unit is ethylene-2,6-naphthalate, etc. are preferable.

[0041] In addition, the polyester may be a recycled polyester, a polyester using a chemical recycling raw material, a polyester using a material recycling raw material, or a polyester using a biomass-derived raw material. When using a recycled polyester, it is preferable that the intermediate layer of the polyester film contains 50% by mass or more of the recycled polyester raw material.

[0042] (Polyester polycondensation catalyst) Examples of the polycondensation catalyst for polycondensing the polyester include antimony compounds, germanium compounds, aluminum compounds, titanium compounds, and the like. Among these, at least one of the antimony compound and the titanium compound is preferable, and in particular, it is preferable to use a polyester obtained using a titanium compound. Therefore, the polyester film preferably contains at least one of the antimony compound and the titanium compound, and more preferably contains a titanium compound.

[0043] By using a titanium compound, the amount of the antimony compound used can be reduced as a result. Therefore, the risk of new protrusion formation due to the precipitation of the antimony compound on the film surface is reduced, and high surface smoothness can be maintained. In addition, by using a titanium compound, the number of metal-containing aggregates derived from the titanium compound, so-called coarse foreign matters, in the film can be reduced, and a polyester film with high surface smoothness, particularly with a small average surface roughness (Sa) on at least one side, can be obtained. Therefore, as a particularly preferable form, when the polyester film has a multilayer structure, a form in which the polyester constituting at least one surface layer uses a titanium compound can be mentioned.

[0044] The titanium element content derived from the titanium compound in the surface layer is preferably 3 ppm or more and 40 ppm or less, more preferably 4 ppm or more and 35 ppm or less. Further, when the surface layer contains at least one of an antimony compound and a titanium compound, the antimony element content in the surface layer is preferably 0 ppm or more and 100 ppm or less. Within such a range, foreign matters caused by the catalyst can be reduced without reducing the production efficiency. From the viewpoints of productivity and cost, it is preferable that the polyester constituting the layer other than the surface layer does not use a titanium compound. On the other hand, by including a titanium compound in the surface layer, a polyester film having excellent smoothness can be obtained.

[0045] (Intrinsic viscosity (IV) of polyester) The intrinsic viscosity (IV) of the polyester constituting the polyester film of the present invention is preferably 0.50 dL / g or more, more preferably 0.55 dL / g or more, and even more preferably 0.60 dL / g or more. By using a polyester having an intrinsic viscosity (IV) of 0.50 dL / g or more as the polyester, the shear stress during polyester kneading increases, the particles in the polyester resin are easily highly dispersed, and the smoothness of one surface (surface layer A) of the polyester film can be enhanced. Further, from the viewpoint of particle dispersibility, the upper limit of the intrinsic viscosity (IV) of the polyester is preferably 1.00 dL / g or less, more preferably 0.85 dL / g or less, and even more preferably 0.75 dL / g or less.

[0046] When this polyester film has a multilayer structure, it is preferable that the intrinsic viscosity (IV) of the polyester constituting the surface layer is within the above range. Note that the "intrinsic viscosity (IV) of the polyester" means the intrinsic viscosity (IV) of a mixed resin when two or more types of polyesters having different intrinsic viscosities (IV) are used.

[0047] (Particles) In this polyester film, particles may be blended mainly for the purpose of imparting slipperiness and preventing the occurrence of scratches in each process. When the polyester film has a layer structure of surface layer A / intermediate layer B / surface layer C, by containing fine particles in surface layer A, it becomes easier to control the surface characteristics of resin layer A provided on surface layer A, and scratch resistance and releasability can be enhanced more effectively.

[0048] From the viewpoints of improving scratch resistance and releasability, the particle content in surface layer A is preferably 500 ppm or more and 3000 ppm or less, more preferably 600 ppm or more and 3000 ppm or less, still more preferably 800 ppm or more and 2800 ppm or less, and particularly preferably 800 ppm or more and 2500 ppm or less, by mass ratio.

[0049] When the polyester film has a layer structure of surface layer A / intermediate layer B / surface layer C, surface layer C is the surface layer formed on the surface opposite to surface layer A. When the polyester film has a layer structure of surface layer A / intermediate layer B / surface layer C and no other resin layer or the like is provided on surface layer C, the surface C of the release film is the surface of surface layer C. Surface layer C preferably contains particles from the viewpoint of improving the handleability and scratch resistance of this film.

[0050] Examples of the particles that the polyester film may contain include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide; crosslinked polymer particles such as crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, and crosslinked polyester particles; and organic particles such as calcium oxalate and ion exchange resin. Among these, crosslinked polymers, silica, calcium carbonate, and aluminum oxide are preferred. Examples of the composition of the crosslinked polymer of the organic particles include crosslinked polymer particles such as divinylbenzene polymers, ethylvinylbenzene-divinylbenzene copolymers, styrene-divinylbenzene copolymers, styrene-ethylvinylbenzene-divinylbenzene copolymers, ethylene glycol dimethacrylate polymers, styrene-ethylene glycol dimethacrylate copolymers, and methyl methacrylate-divinylbenzene copolymers. Note that crosslinked polymer particles composed of a system of three or more components may be used, and those that are copolymers of divinylbenzene, methylstyrene, methacrylic acid, and styrene are preferred. The surface layer A and the surface layer C preferably contain the above particles. In this case, the above particles may be single or used in combination of two or more kinds.

[0051] From the viewpoint of improving the handleability and scratch resistance of the polyester film, the average particle size (average primary particle size) of the particles is preferably 0.1 to 1.5 μm, more preferably 0.1 to 1.2 μm, and even more preferably 0.2 to 1.0 μm.

[0052] Also, the particles particularly preferably have a substantially uniform average particle size with a narrow particle size distribution (so-called monodispersity). As particles having a substantially uniform average particle size with a narrow particle size distribution, in the particle size distribution of the particles, when the particle diameter at which the cumulative number is 10% is D10, the particle diameter at which the cumulative number is 50% is D50, and the particle diameter at which the cumulative number is 90% is D90, particles with (D90 - D10) / D50 of 0.4 or less are preferred, and particles with 0.2 or less are particularly preferred. The relational expression (D90 - D10) / D50 indicates the variation in particle size based on D50. Particles with (D90 - D10) / D50 of 0.4 or less have a sharp particle size distribution with a small difference between D90 and D10. For this film, while maintaining excellent handleability, extremely high smoothness can be imparted, and it is easy to improve the anti-scratch property. The particle size distribution of the particles is measured by a laser diffraction type measuring device.

[0053] When the polyester film has a layer structure of surface layer A / intermediate layer B / surface layer C, from the viewpoint of improving the handleability and anti-scratch property of this film, surface layer C preferably contains two or more types of particles with different particle sizes. Specifically, it preferably contains first particles with a particle size of 0.1 to 0.5 μm and second particles with a particle size of 0.6 to 1.5 μm. Regarding the measurement method, when two or more different types of particles are contained in the resin layer, for example, the particle size can be measured using a scanning electron microscope.

[0054] Also, the maximum value of the difference in particle size between the first particles and the second particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more. When the difference in particle size is 0.1 μm or more, it is easy to improve the slipperiness of the surface of the polyester film, and it is easy to improve the handleability and anti-scratch property of this film. Also, from the viewpoint of suppressing damage to the surface of the resin layer due to unevenness and corresponding to the elongation of the polyester film roll, the upper limit of the maximum value of the difference in particle size is preferably 1.5 μm or less, more preferably 1.2 μm or less, and even more preferably 1.0 μm or less.

[0055] In addition, when the polyester film has a layer structure of surface layer A / intermediate layer B / surface layer C, surface layer C preferably has both an average surface roughness (Sa) and a maximum peak height (Sp) that are equal to or greater than those of surface layer A. It is preferable that the average surface roughness (Sa) of surface layer C is 10 nm or more or the maximum peak height (Sp) is 400 nm or more.

[0056] The intermediate layer B preferably functions as the thickest main layer, and in order to reduce costs, it preferably contains substantially no particles or contains particles at a lower concentration than at least the surface layer C. Examples of the particles used in the intermediate layer B are the same as those described above. Note that "substantially not contained" means not intentionally contained, and specifically refers to a particle content (particle concentration) of 200 ppm or less, more preferably 150 ppm or less.

[0057] (Others) In order to suppress the precipitation amount of the oligomer component, a polyester film may be produced using a polyester having a low content of the oligomer component as a raw material. As a method for producing a polyester having a low content of the oligomer component, various known methods can be used, such as a method of subjecting the polyester to solid-phase polymerization after production. Further, the polyester film may have a three-layer or more structure, and the surface layer of the polyester film may be a layer using a polyester raw material having a low content of the oligomer component, thereby suppressing the precipitation amount of the oligomer component. Further, the polyester may be obtained by performing an esterification or transesterification reaction and then increasing the reaction temperature and performing melt polycondensation under reduced pressure.

[0058] In addition to the above-mentioned particles, conventionally known ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. can be added to the polyester film as needed.

[0059] (Method for producing polyester film) Next, the manufacturing examples of this polyester film will be specifically described, but it is not limited to the following manufacturing examples in any way. For example, when manufacturing a biaxially stretched film, a method of extruding the dried pellets of the polyester raw material described above from a die as a molten sheet using an extruder and cooling and solidifying it with a cooling roll to obtain an unstretched sheet is preferred. In this case, it is preferable to enhance the adhesion between the sheet and the rotating cooling drum in order to improve the flatness of the sheet, and the electrostatic printing adhesion method and / or the liquid coating adhesion method are preferably adopted.

[0060] Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or tenter-type stretching machine. The stretching temperature is preferably 70 to 120 °C, more preferably 80 to 110 °C, and the stretching ratio is preferably 2.5 to 7.0 times, more preferably 3.0 to 6.0 times. Next, it is stretched in a direction perpendicular to the first-stage stretching direction. In that case, the stretching temperature is preferably 70 to 170 °C, and the stretching ratio is preferably 3.0 to 7.0 times, more preferably 3.5 to 6.0 times. Then, subsequently, heat treatment is preferably performed at a temperature of 180 to 270 °C under tension or under relaxation within 30% to obtain a biaxially stretched film. 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 it so that the biaxial stretching ratios finally fall within the above ranges respectively.

[0061] Also, the simultaneous biaxial stretching method can be adopted in the manufacture of this polyester film. The simultaneous biaxial stretching method is a method of simultaneously stretching and orienting the unstretched sheet in the machine direction and the width direction in a state where the temperature is preferably controlled at 70 to 120 °C, more preferably 80 to 110 °C. As the stretching ratio, the area ratio is preferably 4 to 50 times, more preferably 7 to 35 times, and even more preferably 10 to 25 times. Subsequently, preferably at a temperature of 170 to 250°C, heat treatment is carried out under tension or with relaxation within 30% to obtain a stretched and oriented film. Regarding the biaxial stretching device that employs the above stretching method, conventionally known stretching methods such as the screw method, the pantograph method, and the linear drive method can be adopted.

[0062] (Resin layer A (release layer)) This release film is provided with a resin layer A on one surface A of the base film. Note that surface A is one of the two surfaces of the base film. When the base film has a single-layer structure, a resin layer A is present on one surface of the base film, and the other surface of the base film where the resin layer A is not laminated becomes surface C. Also, when the base film has a multilayer structure and the base film has a layer structure of surface layer A / intermediate layer B / surface layer C, the resin layer A is laminated on the surface of surface layer A, resulting in a structure of resin layer A / surface layer A / intermediate layer B / surface layer C, and the surface of surface layer C becomes surface C.

[0063] When the base film has a layer structure of surface layer A / intermediate layer B / surface layer C, the average surface roughness (Sa) of the surface of surface layer A is preferably 1 to 10 nm, more preferably 2 to 8 nm, and even more preferably 2 to 6 nm. Thereby, it becomes easy to control the average surface roughness (Sa) of the resin layer A surface within the above range. By laminating the resin layer A on such a highly smooth surface layer A, when forming and laminating a further resin layer (for example, an insulating layer, etc.) on the resin layer A to form a laminated sheet, the surface of the resin layer (for example, an insulating layer, etc.) can be made highly smooth.

[0064] The film thickness of the resin layer A is preferably in the range of 0.003 to 1 μm, more preferably 0.005 to 0.5 μm, and even more preferably 0.01 to 0.2 μm. By setting the film thickness of the resin layer A within the above range, good appearance and transparency can be achieved while obtaining sufficient release properties.

[0065] The resin layer A is preferably directly laminated on one surface A of the base film, but it may also be laminated on one surface A of the base film through another layer. Examples of the other layer include, in addition to the easy-adhesion coating layer, an antistatic layer, an antiblocking layer, and the like.

[0066] (Non-silicone release agent) The resin layer A contains a non-silicone release agent. The non-silicone release agent is not particularly limited, and examples thereof include wax, a long-chain alkyl group-containing compound, a fluorine compound, and the like. Among them, the non-silicone release agent is preferably at least one selected from a long-chain alkyl compound and wax, and from the viewpoint of releasability, it is more preferably a long-chain alkyl group-containing compound.

[0067] Examples of waxes include natural waxes, synthetic waxes, and modified waxes. Natural waxes include vegetable waxes, animal waxes, mineral waxes, and petroleum waxes. Vegetable waxes include candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil. Animal waxes include beeswax, lanolin, and sperm whale oil. Mineral waxes include montan wax, ozokerite, and ceresin. Petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum. Synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, and ketones. Well-known synthetic hydrocarbons include Fischer-Tropsch wax (also known as Sasol wax) and polyethylene wax. In addition, the following polymers, which are low molecular weight polymers (specifically, polymers having a viscosity-average molecular weight of 500 to 20,000), are also included. Examples of such polymers include polypropylene, ethylene-acrylic acid copolymer, polyethylene glycol, polypropylene glycol, and block or graft conjugates of polyethylene glycol and polypropylene glycol. Modified waxes include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. Here, the derivative is a compound obtained by any one of purification, oxidation, esterification, saponification, or a combination thereof. Hydrogenated waxes include hydrogenated castor oil and hydrogenated castor oil derivatives. Among these waxes, synthetic hydrocarbon-based waxes are preferred from the viewpoints of stable performance and easy availability, and oxidized polyethylene wax and oxidized polypropylene wax are more preferred.

[0068] The number average molecular weight of the synthetic wax is preferably in the range of 500 to 30,000, more preferably in the range of 1,000 to 15,000, and even more preferably in the range of 2,000 to 8,000. Further, the melting point or softening point of the wax is preferably 80°C or higher, more preferably 110°C or higher. The melting point or softening point of the above wax is preferably 200°C or lower, more preferably 170°C or lower, and even more preferably 150°C or lower.

[0069] The long-chain alkyl compound is a compound containing a long-chain alkyl group. More specifically, the long-chain alkyl compound refers to a compound having a linear or branched alkyl group with 6 or more carbon atoms, preferably 8 or more carbon atoms, and even 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, etc. The long-chain alkyl compound is not particularly limited, and examples thereof include a polyvinyl compound containing a long-chain alkyl group, an acrylic compound containing a long-chain alkyl group, a polyester compound containing a long-chain alkyl group, an amine compound containing a long-chain alkyl group, an ether compound containing a long-chain alkyl group, a quaternary ammonium salt containing a long-chain alkyl group, etc. Considering heat resistance and contamination, the long-chain alkyl compound is preferably a high molecular compound. Also, considering mold release properties and ease of handling, a polyvinyl compound containing a long-chain alkyl group is preferred.

[0070] The fluorine compound is a compound containing fluorine atoms in the compound. As the fluorine compound, an organic fluorine compound is preferably used in terms of the coating appearance by in-line coating. Examples thereof include a compound containing a perfluoroalkyl group, a polymer of an olefin compound containing fluorine atoms, an aromatic fluorine compound such as fluorobenzene, etc. Considering heat resistance and contamination, it is preferably a high molecular compound.

[0071] The content of the non-silicone release agent in the resin layer A is preferably in the range of 5 to 90% by mass, more preferably 10 to 70% by mass, still more preferably 15 to 65% by mass, and particularly preferably 20 to 60% by mass with respect to the total mass of the resin layer A. By setting the content of the non-silicone release agent within the above range, the present release film can exhibit good releasability even in a high-temperature environment.

[0072] (Crosslinking agent) The coating liquid A for forming the resin layer A contains a crosslinking agent. There is no particular limitation on the crosslinking agent, and conventionally known crosslinking agents can be used. Examples thereof include melamine compounds, oxazoline compounds, epoxy compounds, carbodiimide compounds, isocyanate compounds, and silane coupling compounds. Among them, from the viewpoint of imparting durability to the resin layer A, it is preferable to contain at least one selected from the group consisting of melamine compounds, oxazoline compounds, and isocyanate compounds.

[0073] (Melamine compound) A melamine compound refers to a compound having a melamine skeleton in the compound. For example, an alkylolated melamine derivative, a compound obtained by reacting an alkylolated melamine derivative with an alcohol to be partially or completely etherified, and a mixture thereof can be used. Examples of alkylolation include methylolation, ethylolation, isopropylolation, n-butylation, and isobutylation. Among these, from the viewpoint of reactivity, methylolation is preferable. As the alcohol used for etherification, methanol, ethanol, isopropanol, n-butanol, isobutanol, etc. are preferably used, and among these, methanol is more preferable. The melamine compound may be either a monomer or a multimer of dimer or higher, or a mixture thereof may be used. Furthermore, a compound obtained by co-condensing urea or the like with a part of melamine may also be used, and in order to increase the reactivity of the melamine compound, a catalyst may be further used in the coating liquid.

[0074] (Oxazoline compound) An oxazoline compound is a compound having an oxazoline group in the molecule, and a polymer containing an oxazoline group is particularly preferred. A polymer containing an oxazoline group can be produced by polymerization of an addition-polymerizable oxazoline group-containing monomer alone or with other monomers. Examples of the addition-polymerizable oxazoline group-containing monomer include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline, etc., and a mixture of one or more of these can be used. Among these, 2-isopropenyl-2-oxazoline is industrially easily available and suitable. Other monomers are not limited as long as they are monomers copolymerizable with the addition-polymerizable oxazoline group-containing monomer. For example, (meth)acrylic acid esters such as alkyl (meth)acrylates (alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, and cyclohexyl group); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated amides such as (meth)acrylamide, N-alkyl (meth)acrylamide, and N,N-dialkyl (meth)acrylamide (alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogen-containing α,β-unsaturated monomers such as vinyl chloride and vinylidene chloride; α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, etc., and one or more of these monomers can be used. Further, the oxazoline compound may have a polyalkylene oxide chain such as a polyethylene oxide chain, and for example, a (meth)acrylate having a polyalkylene oxide chain may be used as another monomer. From the viewpoint of improving the adhesion of the resin layer A to the polyester film, the amount of oxazoline groups in the oxazoline compound is preferably in the range of 0.5 to 10 mmol / g, more preferably 1 to 9 mmol / g, and still more preferably 3 to 8 mmol / g.

[0075] (Epoxy compound) An epoxy compound is a compound having an epoxy group in the molecule, and examples thereof include condensates with hydroxyl groups or amino groups such as epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, polyepoxy compounds, diepoxy compounds, monoepoxy compounds, and glycidylamine compounds. Examples of the polyepoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. Examples of the diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polytetramethylene glycol diglycidyl ether. Examples of the monoepoxy compound include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether. Examples of the glycidylamine compound include N,N,N’,N’-tetraglycidyl-m-xylenediamine and 1,3-bis(N,N-diglycidylamino)cyclohexane. From the viewpoint of improving the adhesion of the resin layer A to the polyester film, a polyether-based epoxy compound is preferred. Also, as the amount of epoxy groups, a polyepoxy compound having three or more functional groups (more than bifunctional) is preferred.

[0076] (carbodiimide compound) A carbodiimide compound is a compound having a carbodiimide structure, that is, a compound having one or more carbodiimide structures in the molecule. For better adhesion between the resin layer A and the polyester film, a polycarbodiimide compound having two or more carbodiimide structures in the molecule is more preferred.

[0077] The carbodiimide compound can be synthesized by a conventionally known technique, and generally, a condensation reaction of a diisocyanate compound is used. The diisocyanate compound is not particularly limited, and either an aromatic type or an aliphatic type can be used. Specifically, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane 4,4’-diisocyanate can be mentioned.

[0078] The content of the carbodiimide group contained in the carbodiimide compound is preferably in the range of 100 to 1000 in terms of carbodiimide equivalent (the weight [g] of the carbodiimide compound for providing 1 mol of carbodiimide group), more preferably in the range of 250 to 800, and still more preferably in the range of 300 to 700. By using within the above range, the durability of the resin layer A is improved.

[0079] Furthermore, within the range not impairing the gist of the present invention, a surfactant may be added to improve the water solubility and water dispersibility of the polycarbodiimide compound, or a hydrophilic monomer such as a polyalkylene oxide, a quaternary ammonium salt of a dialkylamino alcohol, and a hydroxyalkyl sulfonate may be added and used.

[0080] (Isocyanate compound) The isocyanate compound refers to a compound having an isocyanate or an isocyanate derivative structure typified by a blocked isocyanate. Examples of the isocyanate compound include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; aliphatic isocyanates having an aromatic ring such as α,α,α’,α’-tetramethylxylylene diisocyanate; aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; and alicyclic isocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate), and isopropylidene dicyclohexyl diisocyanate. In addition, polymers and derivatives such as biuret compounds, isocyanurate compounds, uretdione compounds, and carbodiimide-modified products of these isocyanates can also be mentioned. These may be used alone or in combination of multiple types. Among the above isocyanate compounds, aliphatic isocyanates or alicyclic isocyanates are more preferable in order to avoid yellowing due to ultraviolet rays.

[0081] Among them, the crosslinking agent is preferably a blocked isocyanate, and particularly preferably an active methylene block isocyanate compound. The active methylene block isocyanate compound is a compound having a structure in which the isocyanate group of the precursor isocyanate compound is protected by an active methylene compound. The active methylene block polyisocyanate compound can be synthesized by reacting the isocyanate group of the polyisocyanate compound with an active methylene-based blocking agent. By using an active methylene block isocyanate compound as the crosslinking agent, the moisture and heat resistance of the resin layer A can be improved.

[0082] Examples of the isocyanate compound that is the precursor of the active methylene block isocyanate compound include aliphatic isocyanate compounds, alicyclic isocyanate compounds, aromatic isocyanate compounds, and the like. From the viewpoint that these isocyanate compounds can react more highly and improve the heat resistance of the release layer, it is more preferable to use a compound having a plurality of isocyanate groups, that is, a polyisocyanate compound, to form an active methylene block polyisocyanate compound.

[0083] Examples of the active methylene-based blocking agent include isobutanoyl acetic acid ester, n-propanoyl acetic acid ester, n-butanoyl acetic acid ester, n-pentanoyl acetic acid ester, n-hexanoyl acetic acid ester, 2-ethylheptanoyl acetic acid ester, malonic acid ester, acetoacetic acid ester, acetylacetone, and the like. Among them, isobutanoyl acetic acid ester, n-propanoyl acetic acid ester, n-butanoyl acetic acid ester, n-pentanoyl acetic acid ester, n-hexanoyl acetic acid ester, 2-ethylheptanoyl acetic acid ester are preferable in terms of excellent low-temperature curability and storage stability in the presence of water. More preferably, isobutanoyl acetic acid ester, n-propanoyl acetic acid ester, n-pentanoyl acetic acid ester are used, and still more preferably, isobutanoyl acetic acid ester is used. More specifically, examples of the isobutanoyl acetic acid ester include methyl isobutanoyl acetate, ethyl isobutanoyl acetate, n-propyl isobutanoyl acetate, isopropyl isobutanoyl acetate, n-butyl isobutanoyl acetate, isobutyl isobutanoyl acetate, t-butyl isobutanoyl acetate, n-pentyl isobutanoyl acetate, n-hexyl isobutanoyl acetate, 2-ethylhexyl isobutanoyl acetate, phenyl isobutanoyl acetate, benzyl isobutanoyl acetate, and the like. Among them, methyl isobutanoyl acetate and ethyl isobutanoyl acetate are preferable. Examples of the n-propanoyl acetic acid ester include methyl n-propanoyl acetate, ethyl n-propanoyl acetate, isopropyl n-propanoyl acetate, n-butyl n-propanoyl acetate, t-butyl n-propanoyl acetate, and the like. Among them, methyl n-propanoyl acetate and ethyl n-propanoyl acetate are preferable. Examples of the n-pentanoyl acetic acid ester include methyl n-pentanoyl acetate, ethyl n-pentanoyl acetate, isopropyl n-pentanoyl acetate, n-butyl n-pentanoyl acetate, t-butyl n-pentanoyl acetate, and the like. Among them, methyl n-pentanoyl acetate and ethyl n-pentanoyl acetate are preferable.

[0084] In the active methylene block isocyanate compound, the above-described active methylene-based blocking agent can be used alone, or two or more thereof can be used in combination. As the active methylene-based blocking agent to be used in combination, dimethyl malonate and diethyl malonate are preferable in terms of excellent low-temperature curability and excellent heat resistance of the formed release layer.

[0085] Further, the active methylene block isocyanate compound can also be used in combination with existing blocking agents, for example, oxime-based, pyrazole-based, alcohol-based, alkylphenol-based, phenol-based, mercaptan-based, acid amide-based, acid imide-based, imidazole-based, urea-based, amine-based, imine-based, bisulfite blocking agents, etc. during the blocking reaction. The existing blocking agents to be used in combination may be used alone or in two or more kinds.

[0086] Examples of oxime-based blocking agents include formaldehyde oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime, etc. Examples of pyrazole-based blocking agents include pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, etc. Examples of alcohol-based blocking agents include methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, etc. Examples of alkylphenol-based blocking agents include monoalkylphenols such as n-propylphenol, isopropylphenol, n-butylphenol, sec-butylphenol, t-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, n-nonylphenol, etc., and dialkylphenols such as di-n-propylphenol, diisopropylphenol, isopropyl cresol, di-n-butylphenol, di-t-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-nonylphenol, etc. Examples of phenol-based blocking agents include phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester, etc. Examples of mercaptan-based blocking agents include butyl mercaptan, dodecyl mercaptan, etc. Examples of acid amide-based blocking agents include acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc. Examples of acid imide-based blocking agents include succinimide, maleimide, etc. Examples of imidazole-based blocking agents include imidazole, 2-methylimidazole, etc. Examples of urea-based blocking agents include urea, thiourea, ethylene urea, etc. Examples of amine-based blocking agents include diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, etc. Examples of imine-based blocking agents include ethylene imine, polyethylene imine, etc.

[0087] In order to improve the compatibility in water-based paints, the active methylene block isocyanate compound preferably contains a hydrophilic site. As a method for adding a hydrophilic site to the blocked isocyanate compound, for example, a method of reacting an isocyanate group of an isocyanate compound as a precursor with a hydrophilic compound having active hydrogen can be mentioned.

[0088] Examples of the hydrophilic compound having active hydrogen used in the active methylene block isocyanate compound include polyethylene glycol compounds, carboxylic acid-containing compounds, sulfonic acid-containing compounds, amine-containing compounds, and the like. These hydrophilic compounds may be used alone or in combination of two or more.

[0089] Examples of the polyethylene glycol compound include monoalkoxypolyethylene glycol, polyethylene glycol, polyoxypropylene polyoxyethylene copolymer diol, polyoxypropylene polyoxyethylene block polymer diol, and the like. Among them, monoalkoxypolyethylene glycols such as monomethoxypolyethylene glycol and monoethoxypolyethylene glycol are particularly preferred.

[0090] Examples of the carboxylic acid-containing compound include monohydroxycarboxylic acid, dihydroxycarboxylic acid, or derivatives thereof. Among the carboxylic acid-containing compounds, monohydroxycarboxylic acid or dihydroxycarboxylic acid is preferred, and monohydroxycarboxylic acid is more preferred.

[0091] Specific examples of the carboxylic acid-containing compound include, for example, hydroxypivalic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, or derivatives such as polycaprolactone diol and polyether polyol using these as initiators, and salts thereof.

[0092] Examples of the sulfonic acid-containing compound include aminoethyl sulfonic acid, ethylenediamino-propyl-β-ethyl sulfonic acid, 1,3-propylenediamine-β-ethyl sulfonic acid, N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid, and salts thereof.

[0093] Examples of the amine-containing compound include amino compounds containing a hydroxyl group. Specifically, dimethylethanolamine, diethylethanolamine, etc. can be mentioned.

[0094] Note that the active methylene block isocyanate compound is used in a design to improve the performance of the resin layer by reacting it during the drying process or the film-forming process. It can be presumed that unreacted substances of these cross-linking agents, compounds after the reaction, or mixtures thereof are present in the resulting resin layer.

[0095] In the resin layer A, it is preferable to use a long-chain alkyl compound as the non-silicone release agent and a blocked isocyanate as the cross-linking agent. Further, it is particularly preferable to use a long-chain alkyl compound as the non-silicone release agent and an active methylene block isocyanate compound as the cross-linking agent.

[0096] As the ratio of the cross-linking agent content to the total non-volatile components in the coating liquid A for forming the resin layer A, it is preferably in the range of 3 to 95% by mass, more preferably 10 to 90% by mass, and still more preferably 20 to 75% by mass. By setting the cross-linking agent content within the above range, this release film can exhibit good releasability even in a high-temperature environment.

[0097] (Binder resin) The resin layer A may contain a binder resin. The binder resin can improve the coatability when the coating liquid A is used as the coating liquid.

[0098] Examples of the binder resin include polyester resins, acrylic resins, urethane resins, polyvinyls (such as polyvinyl alcohol and vinyl chloride-vinyl acetate copolymers), polyalkylene glycols, polyalkylene imines, methyl cellulose, hydroxy cellulose, starches, etc. Among these, polyester resins, acrylic resins, and urethane resins are preferred in terms of easy control of releasability, and polyester resins are more preferred.

[0099] Examples of the main constituent components of the polyester resin include those composed of the following polycarboxylic acids and polyhydroxy compounds. Examples of 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, etc. Examples of 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, etc. One or more of these compounds can be appropriately selected from among them, and the polyester resin can be synthesized by a conventional polycondensation reaction.

[0100] An acrylic resin is a polymer composed of polymerizable monomers having a carbon-carbon double bond, such as those represented by acrylic and methacrylic monomers. These may be either homopolymers or copolymers. In addition, acrylic resins include polymers (in some cases, mixtures of polymers) obtained by polymerizing polymerizable monomers containing acrylic or methacrylic monomers in a polyester solution or a polyester dispersion. Similarly, polymers (in some cases, mixtures of polymers) obtained by polymerizing the above polymerizable monomers in a polyurethane solution or a polyurethane dispersion are also included. Similarly, polymers (in some cases, polymer mixtures) obtained by polymerizing the above polymerizable monomers in other polymer solutions or dispersions are also included, and these are also referred to as (meth)acrylic-modified polyester resins and (meth)acrylic-modified polyurethane resins in this specification. The above-mentioned polyesters and polyurethanes used in (meth)acrylic resins can be appropriately selected and used from those exemplified as the polyesters and polyurethanes used in the binder resins described later. In addition, (meth)acrylic resins can also contain hydroxyl groups and amino groups in order to further improve the adhesion to polyester films.

[0101] The polymerizable monomer having the carbon-carbon double bond is not particularly limited, but as particularly representative compounds, 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, etc.; phosphorus-containing vinyl monomers; various vinyl halides such as vinyl chloride, vinylidene chloride; and various conjugated dienes such as butadiene can be mentioned.

[0102] A urethane resin is a high molecular compound having a urethane bond in the molecule. Usually, a urethane resin is produced by the reaction of a polyol and an isocyanate. Examples of the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols, and these compounds may be used alone or in combination of multiple types.

[0103] 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, and the like. Examples of carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and the like. Examples of polycarbonate polyols obtained from these reactions include poly(1,6-hexylene) carbonate, poly(3-methyl-1,5-pentylene) carbonate, and the like.

[0104] 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.).

[0105] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene - propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, etc.

[0106] 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.

[0107] 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.

[0108] 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-propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexane diamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octane diamine, 1,9-nonane diamine, 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.

[0109] The urethane resin may be based on a solvent, but is preferably based on water. 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 and transparency of the resulting coating layer. Examples of the ionic group to be introduced include various ones such as a carboxyl group, sulfonic acid, phosphoric acid, phosphonic acid, and quaternary ammonium salt, with a carboxyl group being preferable. As a method for introducing a carboxyl group into the 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 groups by using a carboxyl group-containing diol depending on the charged amount of this component is preferable. For example, dimethylolpropionic acid, dimethylolbutanoic acid, bis-(2-hydroxyethyl)propionic acid, bis-(2-hydroxyethyl)butanoic acid, etc. can be copolymerized with the diol used for the polymerization of the urethane resin. Further, this carboxyl group is preferably in the form of a salt neutralized with ammonia, an amine, an alkali metal, an inorganic alkali, etc. Particularly preferable ones are ammonia, trimethylamine, and triethylamine. Such a polyurethane resin can use the carboxyl group from which the neutralizing agent has been removed as a cross-linking reaction point by another cross-linking agent in the drying process after coating. Thereby, it is excellent in the stability in the state of the liquid before coating, and it is possible to further improve the durability, solvent resistance, water resistance, blocking resistance, etc. of the resulting coating layer.

[0110] (Other components) Also, within a range not impairing the gist of the present invention, it is also possible to use particles in combination for the purpose of improving the blocking property and slipperiness of the resin layer A.

[0111] Furthermore, within the scope not impairing the gist of the present invention, defoaming agents, coating property improvers, thickeners, organic lubricants, antistatic agents, ultraviolet absorbers, antioxidants, foaming agents, dyes, pigments, etc. can be used in combination as necessary for the formation of the resin layer A.

[0112] Analysis of the components in the resin layer A can be performed by analysis such as TOF-SIMS, ESCA, fluorescent X-ray, etc.

[0113] (Method for forming the resin layer A) As a method for forming the resin layer A, for example, conventionally known coating methods such as gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze coating, impregnation coating, kiss coating, spray coating, calendar coating, extrusion coating, etc. can be used.

[0114] For example, when providing the resin layer A by in-line coating, it is preferable to manufacture a release film by coating a coating solution in which the above-mentioned series of compounds are made into an aqueous solution or an aqueous dispersion and adjusted to a solid content concentration of about 0.1 to 50% by mass on a polyester film. Further, within the scope not impairing the gist of the present invention, a small amount of organic solvent may be contained in the coating solution for the purpose of improving the dispersibility in water, improving the film-forming property, etc. The organic solvent may be only one type, or two or more types may be used.

[0115] Regarding the drying and curing conditions when forming the resin layer A on the polyester film, it is not particularly limited. For example, when providing the resin layer by off-line coating, usually, heat treatment is preferably performed at 80 to 200°C for 3 to 40 seconds, preferably at 100 to 180°C for 3 to 40 seconds as a guide.

[0116] On the other hand, when providing a coating layer by in-line coating, usually, heat treatment is preferably performed at 70 to 270°C for 3 to 200 seconds as a guide.

[0117] Also, regardless of offline coating or inline coating, heat treatment and irradiation with active energy rays such as ultraviolet rays may be used in combination as necessary. The polyester film constituting this release film may be previously subjected to surface treatment such as corona treatment or plasma treatment.

[0118] (Resin layer C) This release film may further include a resin layer C on the side opposite to the resin layer A. FIG. 3 is a cross-sectional view for explaining the configuration of the release film 100 including the resin layer C30. As shown in FIG. 3, when the release film 100 includes the resin layer C30, the exposed surface of the resin layer C30 becomes the surface C of the release film 100.

[0119] The resin layer C preferably contains the above-described binder resin and crosslinking agent. The content of the binder resin in the resin layer C is preferably in the range of 0 to 60% by mass, more preferably 10 to 50% by mass, and still more preferably 15 to 50% by mass with respect to the total mass of the resin layer C. Also, the content of the crosslinking agent in the resin layer C is preferably in the range of 0 to 80% by mass, more preferably 10 to 70% by mass, and still more preferably 20 to 60% by mass with respect to the total mass of the resin layer C.

[0120] (Antistatic agent) The resin layer C may contain an antistatic agent. As an example of the antistatic agent, an ion conductive polymer compound can be mentioned. An ion conductive polymer compound is a polymer compound containing an ion conductive functional group, and examples thereof include polymer compounds such as ammonium group-containing compounds, polyether compounds, sulfonic acid compounds, and betaine compounds. Among these, ammonium group-containing compounds are particularly preferable from the viewpoint of high polarity and prevention of peeling charge.

[0121] An ammonium group-containing compound refers to a compound having an ammonium group in the molecule, and is preferably a polymer compound having an ammonium group. For example, a polymer using a monomer having an ammonium group and an unsaturated double bond as a component can be used.

[0122] Specific examples of such polymers include, for example, polymers having repeating units represented by the following formula (1). The ammonium group-containing polymer compound may be a homopolymer or copolymer of these, or may further copolymerize a plurality of other components.

[0123]

Chemical formula

[0124] In the above formula (1), R 1 , R 2 are each independently a hydrogen atom, an alkyl group, a phenyl group, etc., and these alkyl groups and phenyl groups may be substituted with the groups shown below. Substitutable groups are, for example, a hydroxyl group, an amide group, an ester group, an alkoxy group, a phenoxy group, a naphthoxy group, a thioalkoxy group, a thiophenoxy group, a cycloalkyl group, a trialkylammonium alkyl group, a cyano group, a halogen, etc. Also, R 1 and R 2 may be chemically bonded, and the linked R 1 and R 2 are, for example, -(CH2) m -(where m is an integer from 2 to 5), -CH(CH3)CH(CH3)-, -CH=CH-CH=CH-, -CH=CH-CH=N-, -CH=CH-N=C-, -CH2OCH2-, -(CH2)2O(CH2)2-, etc.

[0125] X - in the above formula (1) can be appropriately selected within a range not impairing the gist of the present invention. For example, examples of X - include halogen ions, sulfonates, phosphates, nitrates, alkyl sulfonates, carboxylates, etc.

[0126] Among polymers containing a monomer having an ammonium group and an unsaturated double bond, from the viewpoint of enhancing film-forming properties and obtaining a stable film, the polymer may have other monomers as copolymer components. Examples of other monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate; and acrylamides such as n-methylolacrylamide.

[0127] However, from the viewpoint of further enhancing polarity and preventing peeling electrification, the above polymer is preferably a homopolymer having the repeating unit represented by the above formula (1).

[0128] Also, the number average molecular weight of the ammonium group-containing polymer compound is preferably from 1,000 to 500,000, more preferably from 2,000 to 350,000, and still more preferably from 5,000 to 200,000 or less. By setting the number average molecular weight of the ammonium group-containing polymer compound to 1,000 or more, the strength of the coating film can be enhanced and the heat resistance stability can be enhanced. Also, by setting the number average molecular weight of the ammonium group-containing polymer compound to 500,000 or less, the viscosity of the coating liquid can be controlled within an appropriate range, and the handleability and coatability can be enhanced.

[0129] Also, the antistatic agent (C) is preferably at least one selected from (a1) a polymer in which a compound composed of thiophene or a thiophene derivative is doped with another anionic compound, and (a2) a polymer in which a compound composed of thiophene or a thiophene derivative has an anionic group and is self-doped. Examples of such an antistatic agent include those obtained by polymerizing a compound represented by the following formula (2) or the following formula (3) in the presence of a polyanion.

[0130]

Chemical formula

[0131] In the above formula (2), 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.

[0132]

Chemical formula

[0133] In the above formula (3), n represents an integer from 1 to 4.

[0134] Specific examples of the above polymer include, for example, a polymer having a repeating unit represented by formula (4). The above polymer may be a homopolymer or a copolymer of these, and may further copolymerize with other plural components. However, from the viewpoint of improving the antistatic property, the above polymer is preferably a homopolymer.

[0135]

Chemical formula

[0136] In the above formula (4), the substituent R 1 is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 2 is preferably -O- or -NH-, R 3 is preferably an alkylene group having 1 to 6 carbon atoms or another linking group capable of forming the structure of formula (4), and at least one of R 4 , R 5 and R 6 is a hydrogen atom, and the other substituents are preferably an alkyl group having 1 to 3 carbon atoms or a hydroxyalkyl group having 2 to 3 carbon atoms in the alkyl group, and X - is preferably an alkylsulfonate ion having an alkyl group having 1 to 4 carbon atoms.

[0137] Examples of the polyanion used at the time of coincidence include 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.

[0138] The content of the antistatic agent in the resin layer C is preferably in the range of 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 15 to 65% by mass with respect to the total mass of the resin layer C. By setting the content of the antistatic agent within the above range, the release film can exhibit an excellent antistatic effect.

[0139] (Other components) In the resin layer C, additives such as an antifoaming agent, a coating property improver, a surfactant, a thickener, an organic lubricant, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, and a pigment may be further appropriately blended within a range not impairing the gist of the present invention in addition to the above components.

[0140] (Use) This release film can be suitably used for various release applications (release films for various processes) that require heat resistance. For example, it can be used for various release and process applications such as for dry film resist (DFR), for multilayer circuit boards, and for manufacturing ceramic green sheets of multilayer ceramic capacitors. In release applications and process applications, this release film is used, for example, as a support, and for example, a resin composition of various materials containing a binder resin, a filler, etc. may be applied and laminated on the support.

[0141] In particular, as described above, while the present release film is excellent in smoothness, it has the advantage of maintaining good releasability even after being exposed to a high-temperature atmosphere such as a hot press process and undergoing a manufacturing process of press treatment. Therefore, the present release film is suitable for hot press molding. For example, the present release film is preferably used for printed wiring boards. If the present release film is used as a support for forming an insulating layer when used for printed wiring boards, a uniform insulating layer can be formed. In particular, it is suitable as a support for forming an insulating layer of a printed wiring board mounted on various semiconductor devices used in electric products (such as computers, mobile phones, digital cameras, and televisions) and vehicles (such as motorcycles, automobiles, trains, ships, and airplanes).

[0142] [Laminated Film] The present embodiment relates to a laminated film (hereinafter, also referred to as "the present laminated film") including a resin layer B further on the resin layer A of the above-described release film. FIG. 4 is a cross-sectional view for explaining the configuration of the present laminated film 200. As shown in FIG. 4, the present laminated film 200 includes a resin layer B50 further on the resin layer A20. Although not shown, a resin layer C may be provided on the side opposite to the side where the resin layer A20 is laminated.

[0143] Further, the present embodiment may relate to a laminated film (hereinafter, also referred to as "the present laminated film") including a protective film further on the resin layer B. FIG. 5 is a cross-sectional view for explaining another configuration of the present laminated film 200. As shown in FIG. 5, the present laminated film 200 includes a resin layer B50 further on the resin layer A20, and a protective film 60 further on the resin layer B50. Although not shown, a resin layer C may be provided on the side opposite to the side where the resin layer A20 is laminated.

[0144] (Resin Layer B) As an example of the resin layer B laminated on the resin layer A, an insulating layer is exemplified. In this case, the resin layer B may appropriately contain an epoxy resin, an inorganic filler, a curing agent, and other additives.

[0145] The thickness of the resin layer B (after curing) is preferably 1 to 30 μm, more preferably 1 to 25 μm, still more preferably 2 to 20 μm, and even more preferably 2 to 15 μm.

[0146] (Epoxy resin) Examples of the epoxy resin include alcohol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol C-type epoxy resins, bisphenol S-type epoxy resins, naphthalene-type epoxy resins, phenol novolak-type epoxy resins, cresol novolak-type epoxy resins, bisphenol A novolak-type epoxy resins, biphenyl-type epoxy resins, triphenylmethane-type epoxy resins, dicyclopentadiene-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol-type epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, and epoxy resins obtained by arbitrarily combining these structures. The epoxy resin may be used alone one of the epoxy resins exemplified above, or two or more thereof may be used in combination in any combination and ratio.

[0147] Among them, as the epoxy resin, it is preferable to use an epoxy resin having at least one skeleton selected from a phenyl skeleton (phenol skeleton), naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, and dicyclopentadiene skeleton. From the viewpoint of heat resistance, it is more preferable to use an epoxy resin having at least one selected from a phenyl skeleton, fluorene skeleton, and biphenyl skeleton. From the viewpoints of ease of production and heat resistance, it is even more preferable to use an epoxy resin having at least one skeleton selected from a bisphenol A skeleton, bisphenol F skeleton, and biphenyl skeleton.

[0148] The type and skeleton of the epoxy resin can be confirmed by NMR (nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), SEM (scanning electron microscope) analysis, IPC (inductively coupled plasma) optical emission spectrometry, TGA (thermogravimetric analysis), DSC (differential scanning calorimetry), and various chromatographies, etc.

[0149] (Inorganic filler) Resin layer B preferably contains an inorganic compound as an inorganic filler. The inorganic compound is not particularly limited, and examples thereof include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate, etc. Among these, silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, etc. Also, spherical silica is preferred as the silica. The inorganic filler may be used alone or in combination of two or more.

[0150] (Hardener) Examples of the hardener include isocyanate compounds, polyfunctional phenols, amine compounds, acid anhydride compounds, imidazole compounds, amide compounds, cationic polymerization initiators, organic phosphines, etc.

[0151] (Other additives) The resin layer B may contain components other than the above epoxy resin, inorganic filler, and curing agent. Examples of other components include leveling agents, solvents, curing accelerators (excluding those corresponding to the above crosslinking agents), coupling agents, flame retardants, antioxidants, light stabilizers, plasticizers, reactive diluents, filler pigments, organic fillers, and the like. These other components can be appropriately combined and used according to the desired physical properties of the insulating layer composition.

[0152] (Method for forming the resin layer B) This laminated film is obtained by applying a coating liquid B for forming the above resin layer B onto the surface of the resin layer A of the release film and curing it.

[0153] The method of applying the coating liquid B onto the release film may be a known method. Examples of such coating methods include comma coating method, gravure coating method, reverse coating method, knife coating method, dip coating method, spray coating method, air knife coating method, spin coating method, roll coating method, printing method, slide coating method, curtain coating method, die coating method, casting method, bar coating method, extrusion coating method, and the like.

[0154] The curing conditions of the resin layer B may be appropriately adjusted according to the components and compounding amounts in the composition, but heating conditions of 80 to 200 °C for 1 to 180 minutes are preferred. This heating is preferably carried out in a two-stage treatment of primary heating at 80 to 160 °C for 1 to 30 minutes and secondary heating at 120 to 200 °C, which is 40 to 120 °C higher than the primary heating temperature, for 1 to 150 minutes, in terms of reducing curing defects.

[0155] (Properties of the resin layer B) The glass transition temperature (Tg) of the resin layer B is preferably 200 °C or lower, more preferably 180 °C or lower. Regarding the lower limit value, considering the handleability of the resin layer and the like, 160 °C or higher is preferred. By setting the glass transition temperature (Tg) of the resin layer B within the above range, the adhesiveness with the protective film as described later can be effectively enhanced.

[0156] (Protective film) This embodiment may also relate to a laminated film further provided with a protective film on the resin layer B. The configuration of the protective film is not particularly limited as long as it can suppress damage or deformation of the resin layer B. The protective film may be composed of a single layer of a base material (protective film base material), or may have a structure further including an adhesive layer as the outermost surface layer on the side in contact with the resin layer B in addition to the protective film base material.

[0157] As the base material constituting the protective film, a resin film is preferable. More specifically, a film mainly composed of polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate and polyethylene naphthalate, polyimide or polycarbonate is preferable. The specific configuration of the resin film may be the same as that described for the release film above.

[0158] (Use) This laminated film is used, for example, as a dry film resist (DFR), a multilayer circuit board, or a multilayer ceramic capacitor by being laminated as needed. In these manufacturing processes, it may be exposed to a high-temperature atmosphere such as a pressing process, but this laminated film is also excellent in heat resistance and is thus suitable for hot press molding.

[0159] In particular, this laminated film is preferably used for printed wiring boards. And printed wiring boards are mounted on various semiconductor devices used in electrical products (for example, computers, mobile phones, digital cameras, televisions, etc.) and vehicles (for example, motorcycles, automobiles, trains, ships, airplanes, etc.).

Example

[0160] Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0161] <Production of Polyester> (1) Production of Polyester A 100 parts by mass of dimethyl terephthalate and 65 parts by mass of ethylene glycol were charged into a transesterification reaction tank equipped with a stirrer, a temperature raising device, and a distillate separation column, and heated to 150 °C to melt the dimethyl terephthalate.

[0162] Next, an ethylene glycol solution of magnesium acetate tetrahydrate was added so that the addition amount of magnesium acetate to the obtained polyester was 0.09% by mass. Thereafter, the temperature was raised to 225 °C over 3 hours under normal pressure, and further stirred and held at 225 °C for 1 hour and 15 minutes while distilling off methanol to carry out a transesterification reaction, and the transesterification reaction was substantially completed to obtain a polyester low polymer (oligomer).

[0163] Next, the oligomer was transferred to a polycondensation reaction tank equipped with a stirrer and a distillation tube. An ethylene glycol solution of magnesium acetate tetrahydrate was added to the oligomer after transfer so that the addition amount of magnesium acetate to the obtained polyester resin was 0.09% by mass. Thereafter, an ethylene glycol solution of phosphoric acid was added as a heat stabilizer so that the addition amount of phosphoric acid to the obtained polyester was 0.017% by mass.

[0164] Next, an ethylene glycol solution of tetrabutyl titanate was added to the oligomer as a polycondensation catalyst so that the titanium atom content in the obtained polyester was 4.5 ppm by mass. Thereafter, the pressure was reduced from 101.3 kPa to 0.4 kPa over 85 minutes and held at 0.4 kPa, and the temperature was raised from 225 °C to 280 °C over 2 hours and held at 280 °C for 1.5 hours to carry out a melt polycondensation reaction, obtaining polyester A having an intrinsic viscosity (IV) of 0.63 dL / g.

[0165] (2) Production of Polyester B 0.75% by mass of alumina particles having an average primary particle size of 0.05 μm was added to the above polyester A, and kneaded using a vented twin-screw kneader to obtain polyester B.

[0166] (3) Production of Polyester C 1.0% by mass of silica particles with an average primary particle size of 0.1 μm was added to the above polyester A, and the mixture was kneaded using a vented twin-screw kneader to obtain polyester C.

[0167] (4) Production of Polyester D 0.4% by mass of organic particles with an average primary particle size of 0.34 μm was added to the above polyester A, and the mixture was kneaded using a vented twin-screw kneader to obtain polyester D.

[0168] (5) Production of Polyester E 2.0% by mass of calcium carbonate particles with an average primary particle size of 0.7 μm was added to the above polyester A, and the mixture was kneaded using a vented twin-screw kneader to obtain polyester E.

[0169] The resin compositions obtained by stirring and mixing with the compositions shown in Table 1 below were diluted with water to prepare coating liquids 1 to 9. The compounds used are as follows.

[0170]

Table 1

[0171] (A1): Long-chain alkyl group-containing compound A long-chain alkyl group-containing compound obtained by adding octadecyl isocyanate to polyvinyl alcohol with an average degree of polymerization of 500 and a saponification degree of 88 mol%

[0172] (A2): Wax A wax emulsion obtained by the following method. In an emulsification equipment with a capacity of 1.5 L equipped with a stirrer, a thermometer, and a temperature controller, 300 g of oxidized polyethylene wax with a melting point of 105°C, an acid value of 16 mgKOH / g, a density of 0.93 g / mL, and a number average molecular weight of 5000, 650 g of ion-exchanged water, 50 g of a decaglycerin monooleate surfactant, and 10 g of a 48% aqueous potassium hydroxide solution were added. After replacement with nitrogen and sealing, it was rapidly stirred at 150°C for 1 hour, then cooled to 130°C, passed through a high-pressure homogenizer at 400 atmospheres, and cooled to 40°C to obtain a wax emulsion.

[0173] (B1): Binder resin An aqueous dispersion of a polyester resin copolymerized with the following composition Monomer composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid / / (diol component) ethylene glycol / 1,4-butanediol / diethylene glycol = 56 / 40 / 4 / / 70 / 20 / 10 (mol%)

[0174] (B2): Binder resin An aqueous dispersion of a mixture of an acrylic resin and an oxazoline compound polymerized with the following composition An aqueous dispersion of a mixture in which 90 parts by mass of an acrylic resin formed from methyl methacrylate / ethyl acrylate = 64 / 36 (mass%) and 10 parts by mass of an oxazoline compound are mixed

[0175] (B3): Binder resin Polyvinyl alcohol with a saponification degree of 88 mol% and a polymerization degree of 500

[0176] (C1): Antistatic agent A high molecular compound with a number average molecular weight of 30,000, in which the structural unit of the following formula X-1 and the structural unit of the following formula X-2 are copolymerized at a weight ratio of 95 / 5

Chemical formula

Chemical formula

[0177] (C2): Antistatic agent A polymer compound with a number average molecular weight of 51,000, having a methanesulfonate of 2-(dimethylammonium)ethyl methacrylate as a structural unit

[0178] (C3): Antistatic agent An ammonium group-containing polymer compound with a number average molecular weight of 30,000, obtained by polymerizing the structural units of the following formula

Chemical formula

[0179] (D1): Crosslinking agent Melamine compound: Hexamethoxymethylol melamine

[0180] (D2): Crosslinking agent Block polyisocyanate obtained by the following method. 1000 parts by mass of hexamethylene diisocyanate was stirred at 60 °C, and 0.1 part by mass of tetramethylammonium caprylate was added as a catalyst. After 4 hours, 0.2 part by mass of phosphoric acid was added to stop the reaction, and an isocyanurate-type polyisocyanate composition was obtained. 100 parts by mass of the obtained isocyanurate-type polyisocyanate composition, 42.3 parts by mass of methoxypolyethylene glycol with a number average molecular weight of 400, and 29.5 parts by mass of propylene glycol monomethyl ether acetate were charged and held at 80 °C for 7 hours. Then, the reaction solution temperature was maintained at 60 °C, 35.8 parts by mass of methyl isobutyryl acetate, 32.2 parts by mass of diethyl malonate, and 0.88 part by mass of a 28% methanol solution of sodium methoxide were added and held for 4 hours. 58.9 parts by mass of n-butanol was added, and the reaction solution temperature was held at 80 °C for 2 hours. Then, 0.86 part by mass of 2-ethylhexyl acid phosphate was added to obtain a block polyisocyanate.

[0181] (E1): Particles Silica particles with an average primary particle size of 0.04 μm

[0182] (F1): Additive Amino-2-methylpropanol hydrochloride

[0183] (F2): Additive Zirconium oxychloride

[0184] [Example 1] A raw material obtained by blending 87% of polyester A and 13% of polyester B by mass was used as the raw material for surface layer A, a raw material with 100% polyester A was used as the raw material for intermediate layer B, and a raw material obtained by blending 28% of polyester A, 30% of polyester D, and 22% of polyester E by mass was used as the raw material for surface layer C. They were respectively supplied to an extruder with a vent and melt-extruded at 290°C. Then, with a three-layer (A / B / C) layer structure having surface layers A and C as the outermost layer (surface layer) and intermediate layer B as the intermediate layer, co-extrusion was performed so that the thickness composition ratio was A / B / C = 4 / 33 / 1. Cooling and solidification were carried out on a cooling roll with the surface temperature set at 40°C using the electrostatic printing adhesion method to obtain an amorphous film. At this time, the side where surface layer C was in contact with the cooling roll was used.

[0185] Next, using the roll peripheral speed difference, it was stretched 3.1 times in the longitudinal direction, that is, the MD direction, at a film temperature of 92°C. Then, the coating liquid shown in Table 1 was applied onto surface layer A, and then it was guided to a tenter and stretched 4.4 times in the transverse direction, that is, the TD direction, at 120°C. After heat treatment (fixing) in the tenter was carried out at 226°C, the film was wound onto a 6-inch plastic core in a roll shape to obtain a release film with a thickness of 38 μm.

[0186] [Examples 2 and 3] A release film was obtained in the same manner as in Example 1 except that the coating liquid described in Table 3 was changed.

[0187] [Examples 4 and 5] A release film was obtained in the same manner as in Example 1 except that the raw material formulation of each layer of the polyester film was adjusted as described in Table 2 to control the average particle size and addition amount of the particles.

[0188] [Examples 6 - 8] A polyester film with a thickness composition ratio of A / B / C = 4 / 33 / 1 was obtained in the same manner as in Example 1, except that the raw material formulation of each layer of the polyester film was adjusted as shown in Table 2. Next, using the roll peripheral speed difference, the film was stretched 3.1 times in the longitudinal direction, i.e., the MD direction, at a film temperature of 92°C, and then the coating liquids shown in Table 3 were applied to both sides of the film, respectively. Thereafter, it was guided into a tenter and stretched 4.4 times at 120°C in the transverse direction, i.e., the TD direction, and after heat treatment (fixing) in the tenter was performed at 226°C, the film was wound up in a roll shape on a 6-inch plastic core to obtain a release film with a thickness of 38 μm.

[0189] [Example 9] A release film was obtained in the same manner as in Example 1, except that the coating liquid was changed to that described in Table 3.

[0190] [Comparative Example 1] A polyester film was obtained in the same manner as in Example 1, except that the resin layer A was not provided in Example 1.

[0191] [Comparative Examples 2 and 3] A release film was obtained in the same manner as in Example 1, except that the coating liquid was changed as shown in Table 1 and the thickness of the resin layer A was as shown in Table 3.

[0192] [Measurement and Evaluation Methods] The measurement methods and evaluation methods used in the examples and comparative examples are as follows. The measurement and evaluation results are summarized in Table 3.

[0193] (1) Intrinsic viscosity (IV) 1 g of polyester was precisely weighed, 100 mL of a mixed solvent of phenol / tetrachloroethane = 50 / 50 (mass ratio) was added and dissolved, and the viscosity (IV) was measured at 30°C using a viscosity (IV) measuring device (「VMS - 022UPC·F10」manufactured by Separate Company).

[0194] (2) Particle size (primary particle size) and particle size distribution Using a scanning electron microscope (manufactured by HITACHI, "S3400N"), the powder was observed from the surface of the surface layer A side of the polyester films of the examples and comparative examples. The size of one particle was measured from the obtained image data. Regarding the particle size distribution, a dispersion with a solid content of 0.03 g / mL was prepared by adding a mixed solvent of phenol / tetrachloroethane = 2 / 3 to the particles. For this dispersion, using "MT3300EXII" manufactured by MicrotracBEL, the particle diameter D10 at which the cumulative number becomes 10%, the particle diameter D50 at which the cumulative number becomes 50%, and the particle diameter D90 at which the cumulative number becomes 90% were measured by the laser diffraction scattering method, and (D90 - D10) / D50 was calculated.

[0195] (3) Average surface roughness (Sa), maximum peak height (Sp) Using a surface roughness measuring instrument (manufactured by Ametek, Inc., "NewView" (registered trademark)), the resin layer A and the surface C (resin layer C) of the release film were measured, and the average surface roughness (Sa) and the maximum peak height (Sp) were determined from the obtained surface profile curve.

[0196] (4) Method for measuring the film thickness of the resin layer The surface of the resin layer was stained with RuO4 and embedded in an epoxy resin. Then, the section prepared by the ultra-thin section method was stained with RuO4, and the thickness of the cross-section of the resin layer was measured using a TEM (H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100V).

[0197] (5) Evaluation of the peel strength of resin layer A (before heat treatment) An adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) was pressure-bonded once back and forth on the surface of the resin layer A of the release film with a 2 kg rubber roller, and the peel strength after leaving it at room temperature (25°C) for 1 hour was measured. The peel strength was measured using "Ezgraph" manufactured by Shimadzu Corporation under the condition of a tensile speed of 300 mm / min with 180° peeling.

[0198] (6) Evaluation of the peel strength of resin layer A (after heat treatment) An adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) was pressure-bonded once back and forth on the surface of the resin layer A of the release film using a 2 kg rubber roller, and then heated in an oven at 100 °C for 1 hour. After that, the peel strength was measured after leaving it at room temperature (25 °C) for 1 hour. The peel strength was measured using "Ezgraph" manufactured by Shimadzu Corporation under the condition of a tensile speed of 300 mm / min and 180° peeling.

[0199] (7) Surface specific resistance The release film was conditioned for 30 minutes in an environment of 23 °C and 50% relative humidity. Then, using a high-resistance resistivity meter: High Resista UX MCP-HT800 and a measuring electrode: UR-100 manufactured by Mitsubishi Chemical Analytech Co., Ltd., a measurement was carried out by applying a voltage of 500 V to the surface of the resin layer C of the release film, and the value after 1 minute was taken as the surface resistivity. If the resistance value exceeded the upper limit of the measurable range, it was considered unmeasurable.

[0200] (8) Air leakage index Using a digital Bekk smoothness tester (manufactured by Toyo Seiki Seisaku-sho, Ltd., "DB-2"), in accordance with JIS P8119, the air leakage index was measured in an atmosphere of 23 °C and 50% relative humidity. The pressure of the pressurizing device was 100 kPa, and a container with a volume of 38 ml was used for the vacuum container. The time for 1 mL of air to flow, that is, the time (seconds) until the pressure in the container changed from 50.7 kPa to 48.0 kPa, was measured, and 10 times the obtained number of seconds was taken as the air leakage index. The sample size of the release film was 70 mm square, and 20 sheets were laminated so that the front and back of the test film overlapped to form a test laminated film. Then, a hole with a diameter of 5 mm was made in the center of this test laminated film, and the air leakage index was measured as described above. The larger the value of this air leakage index, the more time it takes for air to leak from the gaps between the films, indicating that the films are in closer contact with each other, and it shows that there is a high risk of wrinkle generation when made into a roll-shaped film.

[0201] (9) Water droplet contact angle The contact angle of the surface of resin layer A of the film sample conditioned for 24 hours or more in an environment of 23°C and 50% relative humidity was measured using an automatic contact angle meter (manufactured by DataPhysics, model "OCA20"). After contacting 2 μL of water droplets with the resin layer surface, the contact angle of the water droplets 30 seconds later was measured.

[0202]

Table 2

[0203]

Table 3

[0204] For the release films of Examples 1 to 9, since the ratio of the release force (F2 / F1) is 15 or less, good releasability can be maintained even after being exposed to a high-temperature atmosphere such as a hot press process. Furthermore, since the surface of resin layer A (release surface) has high smoothness, it is suitable for use in molding resin layers that require high smoothness. Also, by appropriately roughening the surface located on the side opposite to resin layer A, air can be quickly released, enabling the rapid creation of a vacuum state, and it is also preferably used in manufacturing processes that require a vacuum process.

[0205] In Comparative Example 1, since no resin layer was laminated, it was difficult to apply it to hot press molding processing. Also, in Comparative Examples 2 and 3, since the ratio of the release force (F2 / F1) exceeds 15, it was found that there is a high risk that the releasability between the mating adherend and the release layer becomes insufficient after being exposed to a high-temperature atmosphere such as a hot press process and then molded.

Industrial Applicability

[0206] The release film of the present invention can maintain good releasability even after being exposed to a high-temperature atmosphere such as a hot pressing process. Further, preferably, by moderately roughening the anti-release surface side, it can also be applied to a manufacturing process that requires a vacuum process. For example, when used as a support for forming an insulating layer for a printed wiring board, a uniform insulating layer can be formed. In particular, it is suitable as a support for forming an insulating layer of a printed wiring board mounted on various semiconductor devices used in electrical products (such as computers, mobile phones, digital cameras, and televisions, etc.) and vehicles (such as motorcycles, automobiles, trains, ships, and airplanes, etc.).

Explanation of Reference Signs

[0207] 10 Base film (polyester film) 12 Surface layer A 14 Intermediate layer B 16 Surface layer C 20 Resin layer A 30 Resin layer C 50 Resin layer B 60 Protective film 100 Release film 200 Laminated film

Claims

1. A resin layer A is provided on one surface A of a base film, wherein the resin layer A contains a non-silicone release agent and a crosslinking agent, an acrylic adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded onto the resin layer A, and after heat treatment at 100 °C for 1 hour, the peeling force between the resin layer A and the acrylic adhesive tape is defined as F2, when an acrylic adhesive tape (manufactured by Nitto Denko Corporation: No. 31B) is pressure-bonded onto the resin layer A and the peeling force between the resin layer A and the acrylic adhesive tape under an environment of 25 °C is defined as F1, a release film in which the value of F2 / F1 is 15 or less.

2. The release film according to claim 1, wherein the peeling force (F2) is 2700 mN / cm or less.

3. The release film according to claim 1, wherein the peeling force (F1) is 1600 mN / cm or less.

4. In the release film, when the surface located on the side opposite to the resin layer A is defined as surface C, the release film according to claim 1, which satisfies the following conditions (1) and (2); (1) The average surface roughness (Sa) of the surface of the resin layer A is 1 to 10 nm; (2) The maximum height (Sz) of the surface C is 400 nm or more.

5. The release film according to claim 1, wherein the base film is a polyester film.

6. The release film according to claim 5, wherein the polyester film has a three-layer structure.

7. The release film according to claim 6, wherein the intermediate layer of the polyester film contains 50% by mass or more of a recycled polyester raw material.

8. The polyester film has a structure of a surface layer A, an intermediate layer B, and a surface layer C in this order from the side where the resin layer A is laminated, and the surface layer C contains a first particle having a particle size of 0.1 to 0.5 μm and a second particle having a particle size of 0.6 to 1.5 μm. The release film according to claim 6.

9. The release film according to claim 8, wherein the maximum value of the difference in particle size between the first particle and the second particle is 0.1 μm or more.

10. The release film according to claim 1, wherein the non-silicone release agent is at least one selected from a long-chain alkyl compound and wax.

11. The release film according to claim 1, wherein the crosslinking agent is at least one selected from the group consisting of a melamine compound, an oxazoline compound, and an isocyanate compound.

12. The release film according to claim 1, wherein the non-silicone release agent is a long-chain alkyl compound and the crosslinking agent is a blocked isocyanate.

13. The release film according to claim 12, wherein the crosslinking agent is an active methylene blocked isocyanate compound.

14. The release film according to claim 1, further comprising a resin layer C on the side opposite to the resin layer A.

15. The release film according to claim 1, which is for thermocompression molding.

16. The release film according to claim 1, which is for printed wiring boards.

17. A laminated film comprising a resin layer B further on the resin layer A of the release film according to any one of claims 1 to 16.

18. The laminated film according to claim 17, further comprising a protective film on the resin layer B.

19. The laminated film according to claim 17, which is for thermocompression molding.

20. The laminated film according to claim 17, which is for printed wiring boards.

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