Release film

Abstract

The present invention provides a release film in which a resin sheet is not peeled off from the release film during pre-drying, and the resin sheet can be peeled off from the release film without being deformed or broken after drying. A release film according to the present invention has a base material film and a release layer. The release layer contains an acrylic resin A and a crosslinking agent B, and the acrylic resin A contains a component A-1 and a component A-2. In particular, the component A-1 has an alkyl group having 5-10 carbon atoms, the release layer is substantially free of a silicone component, and the release layer is laminated on the base material film. The glass transition point of a resin constituting the base material film is 100°C or higher.

Description

[Technical Field]

[0001] This invention relates to a release film that can be used in resin sheet molding and the like. In particular, it relates to a release film for resin sheet molding used in electronic components. [Background technology]

[0002] Conventionally, release films based on polyester film have high heat resistance and mechanical properties, and have been used as process films in solution-based film formation of resin sheets such as adhesive sheets, cover films, polymer electrolyte membranes, and dielectric resin sheets. In recent years, electronic components have become increasingly miniaturized, and therefore, the resin sheets used in electronic components are required to be thinner. When resin sheets are made thinner, there is a possibility that the resin sheet may tear even with a small force when peeling it off the process film. Therefore, release films used as process films have been required to have a small peeling force so that the resin sheet can be peeled off without damaging it. Accordingly, technologies such as those described in Patent Document 1 have been disclosed, and release sheets have been proposed that show little change in peeling force even after a long period of time has elapsed since the release sheet was manufactured on the surface of the release layer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-106150 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in the technology described in Patent Document 1, for example in electronic component applications, a small peeling force is required so that resin sheets and the like can be peeled off without damaging them. On the other hand, if the peeling force is too small, the resin may peel off at unintended times, such as during the pre-drying stage of the resin, which could lead to a decrease in yield.

[0005] In order to improve these problems, a release film with a large peeling force has been proposed. However, in the pre-drying process, although the resin sheet does not peel off from the process film, there is a problem that the resin sheet cannot be peeled off from the process film even after the main drying process, and the original purpose cannot be achieved.

[0006] Also, from the perspective of improving productivity, in addition to thinning the resin sheet, thinning of the release film is also required. However, when the release film is thin, when heat and pressure are applied, the release film is deformed by heat, wrinkles or the like occur, and the peeling force when the resin sheet is peeled off from the release film cannot be kept constant, and there is a problem that the resin sheet is deformed or broken.

[0007] Thus, there is a problem that the existing release film cannot fully exhibit its performance, and improvement thereof is required.

[0008] The present invention solves the above problems, and the resin sheet does not peel off from the release film during pre-drying, and after the main drying, the resin sheet can be peeled off from the release film without being deformed or broken, and even when the release film is thin, the release film does not deform in the heat process, and no deformation or breakage occurs in the resin sheet. The purpose is to provide a release film.

Means for Solving the Problems

[0009] As a result of intensive studies to solve the above problems, the inventors have found that the above object can be achieved by a release film having the following configuration, and completed the present invention.

[0010] That is, the present invention has the following configuration. [1] A release film having a base film and a release layer, <00001​​​​​ A release film in which the glass transition temperature of the resin constituting the base film is 100°C or higher.

[0011] [ka]

[0012] (In general formula (1), R1 is (C n H 2n+1 (n = an integer between 5 and 10, R3 represents H or CH3.) [ka]

[0013] (In general formula (2), R2 is (C m H 2m OH) (m = an integer between 1 and 10) or H, R4 represents H or CH3. [2] The release film according to [1], wherein the molar ratio of component A-1 to the total number of moles of component A-1 and component A-2 is 30 mol% or more and 90 mol% or less.

[0014] [3] The release film according to [1] or [2], wherein the tape peeling force at a release layer peeling speed of 300 mm / min is 5000 mN / 50 mm or more and 15000 mN / 50 mm or less. [4] The Martens hardness of the base film is 150 N / mm². 2 The above is a release film as described in any of [1] to [3]. [5] A release film according to any of [1] to [4], wherein the water contact angle (α) of the release layer surface after heating at 180°C for 1 hour and the water contact angle (β) of the release layer surface before heating satisfy the following equation (1).

[0015] α>β (1) [6] The release film according to any one of [1] to [5], wherein the base film contains a polyester resin having a structural unit derived from naphthalenedicarboxylic acid as a dicarboxylic acid component. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a release film in which a resin sheet does not peel off from the release film during pre-drying, and can be peeled off from the release film without deformation or breakage of the resin sheet after main drying. Further, when heat and pressure are applied to the release film, if it is the release film of the present invention, even when the release film is thin, it is possible to suppress deformation and the occurrence of wrinkles. Moreover, for example, the peeling force when peeling the resin sheet from the release film can be kept constant, and deformation and tearing of the resin sheet can be prevented. Therefore, the resin sheet produced by the release film of the present invention can also be applied to electronic components and the like.

Mode for Carrying Out the Invention

[0017] The release film of the present invention has a base film and a release layer, and the release layer contains an acrylic resin A and a crosslinking agent B, and substantially does not contain a silicone component. The acrylic resin A contains, as a constitutional unit, an A-1 component represented by the following general formula (1) and an A-2 component represented by the following general formula (2).

[0018]

Chemical formula

[0019] (In general formula (1), R1 is (C n H 2n+1 )(n is an integer of 5 or more and 10 or less), and R3 represents H or CH3.)

Chemical formula

[0020] (In general formula (2), R2 is (C m H 2m OH)(m is an integer of 1 or more and 10 or less) or H, and R4 represents H or CH3.) Further, the glass transition point of the resin constituting the base film is 100°C or higher.

[0021] (Base film) The release film in the present invention comprises a base film and a release layer disposed on the surface of the base film. When an object to be released is placed on the release layer of the release film, the object to be released can be molded into the same shape as the base film. Furthermore, since the release layer and the object to be released are easily separated, the shape of the object to be released can be deformed and maintained into a desired shape. The release layer may be disposed on one surface of the base film or on both surfaces.

[0022] In particular, the present invention can suppress deformation that may occur when heat and pressure are applied to the release film, and can also suppress the formation of wrinkles. Furthermore, by achieving these effects, the release film of the present invention can maintain a constant peeling force when the resin sheet to be released is peeled from the release film, thereby suppressing deformation and tearing of the resin sheet.

[0023] Furthermore, by laminating the base film and the release layer in this order, it is possible to maintain a good balance between the dimensional stability and surface smoothness of the base film during heating and the thermal shrinkage and expansion properties of the release layer during heating.

[0024] While interpretation should not be limited to any particular theory, if there is a large difference in the thermal shrinkage and expansion properties between the release layer and the base film, the release film tends to deform and wrinkle when heated. In contrast, with the combination of base film and release layer in the present invention, for example, even after heating at 180°C for 1 hour, the thermal shrinkage and expansion properties of the base film and release layer can be well-balanced.

[0025] As a result, the present invention can be suitably used even when the mold-release material is formed through multiple drying steps, or even when, for example, one of the drying steps includes a step of storage for a long period of time under high temperature conditions exceeding 100°C.

[0026] Furthermore, it is possible to obtain a release film in which the resin sheet does not peel off the release film during pre-drying, the resin sheet can be peeled off the release film without deformation or breakage after main drying, and even if the release film is thin, the release film does not deform during the heat treatment process, and no deformation or tearing occurs in the resin sheet.

[0027] As the base film, any known film with a glass transition temperature of 100°C or higher can be used. For example, a resin film made of polyester such as polyethylene naphthalate, polycarbonate, polyamide-imide, or polyimide can be used as the base film. Polyester films are particularly preferred from the viewpoint of cost and productivity, and polyethylene naphthalate films or copolymers thereof are even more preferred.

[0028] In one embodiment, the base film contains a polyester resin having structural units derived from naphthalenedicarboxylic acid as the dicarboxylic acid component. Although it should not be interpreted as being limited to a specific theory, the fact that the base film is a film containing naphthalenedicarboxylic acid as the dicarboxylic acid component allows for excellent dimensional stability, particularly high surface smoothness, even after heating at 180°C for 1 hour, and the release layer according to the present invention can also maintain surface smoothness. Because the release layer has high surface smoothness after heating, for example, when peeling a resin sheet or the like from the release layer after heating at 180°C for 1 hour, the resin sheet can be peeled off with a constant peeling force. In this way, since the base film can maintain high surface smoothness after heating, the heat treatment temperature can be appropriately selected according to the resin sheet to be manufactured.

[0029] In one embodiment, a composition containing a polyester resin comprises naphthalenedicarboxylic acid as the main component of the dicarboxylic acid component.

[0030] The thickness of the base film is preferably 10 μm to 188 μm, and more preferably 16 μm to 100 μm. A base film thickness of 10 μm or more suppresses deformation due to heat during base film production, processing, and molding. On the other hand, a base film thickness of 188 μm or less allows for the reduction of the amount of base film discarded after use while still meeting the required physical properties of the base film, thereby reducing the environmental burden. Furthermore, a base film thickness of 100 μm or less is preferable because it allows for the production of longer roll lengths in a single production run, improving productivity from the standpoint of base film loss and transportability.

[0031] A coating for improved adhesion may be placed between the base film and the release layer. Furthermore, a coating for properties such as slipperiness, heat resistance, and antistatic properties may be placed on the side of the base film opposite to the side where the release layer is placed.

[0032] The average surface roughness (Sa) of the surface on which the release layer of the base film used in the present invention is laminated is preferably in the range of 1 to 50 nm, and more preferably in the range of 2 to 30 nm. The maximum protrusion height (P) of the surface on which the release layer of the base film used in the present invention is laminated is preferably 2 μm or less, and more preferably 1.5 μm or less. If Sa is 50 nm or less and P is 2 μm or less, it is possible to suppress thickness unevenness of the release layer and maintain a constant smoothness of the surface of the release layer, furthermore, thickness unevenness of the object to be released can be reduced, and the possibility of the object to be released tearing starting from a thin part when peeled off from the release film can be suppressed.

[0033] The average surface roughness (Sa) of the region of the base film used in this invention opposite to the surface on which the release layer is laminated is preferably in the range of 3 to 100 nm, and more preferably 5 to 30 nm. The maximum protrusion height (P) of the base film used in this invention opposite to the surface on which the release layer is laminated is preferably 2 μm or less, and more preferably 1.5 μm or less. If Sa is 3 nm or more, the slipperiness between the release surface and the non-release surface is improved, resulting in excellent winding performance. Furthermore, if P is 2 μm or less, damage to the surface of the release layer is not caused when winding, and the possibility of the release layer partially peeling off is reduced. In addition, when the object to be released is peeled from the release film, the possibility of tearing starting from the peeled-off portion of the release layer can be suppressed.

[0034] The haze of the base film used in the present invention is preferably 0.1% to 20%, for example, 3% to 17%, and may also be 6% to 15%. Although the mechanism has not yet been analyzed, it is presumed that having the above haze value allows the base film to maintain appropriate surface irregularities when the release film is dried at high temperatures, contributing to the cooling properties of the release film, and thus tends to exhibit desirable heat resistance in the release film. Furthermore, it tends to exhibit a greater interaction with the release layer in the present invention.

[0035] The base film in this invention can be made from recycled polyester film scraps and recycled PET bottles. Because this invention can use such recycled film scraps and recycled PET bottles, the environmental impact can be greatly reduced. Furthermore, even in embodiments that include recycled film scraps and recycled PET bottles, the slipperiness of the film and the ease of air release can be maintained. The release layer in this invention allows for the proper collection, processing, and reuse of polyester film used in various applications.

[0036] When such recycled raw materials are included, the material may contain fine particles of a size such that the average surface roughness (Sa) of the surface on which the release layer of the base film is laminated is in the range of 1 to 50 nm, and may also contain fine particles of a size such that the maximum protrusion height (P) of the surface on which the release layer of the base film is laminated is 2 μm or less.

[0037] For example, the base film in the present invention may have fine particles with a size in the range of 0.001 μm to 10 μm. Fine particles having a size in this range can satisfy the above-mentioned average surface roughness (Sa) and maximum protrusion height (P) of the surface on which the release layer of the base film is laminated.

[0038] In one embodiment, the base film has a surface layer that is substantially free of inorganic particles, and a release layer may be laminated on this surface layer.

[0039] The glass transition temperature of the resin constituting the base film used in the present invention is preferably 100°C or higher, more preferably 110°C or higher, and most preferably 115°C or higher. When it is 100°C or higher, even when heat and pressure are applied when forming the resin sheet on the release film, the release film itself does not deform and its flatness is maintained, so a resin sheet of uniform thickness can be formed, which is preferable. When it is 115°C or higher, it is particularly preferable because a resin sheet of even more uniform thickness can be formed without impairing the flatness of the film. The glass transition temperature is, for example, 150°C or lower, may be 140°C or lower, or 130°C or lower. In one embodiment, the glass transition temperature of the resin constituting the base film is 110°C or higher and 150°C or lower, for example, 115°C or higher and 140°C or lower, or 115°C or higher and 135°C or lower.

[0040] Due to these characteristics, the present invention allows for the removal of resin sheets from the release layer with a constant peeling force, even when subjected to a heat treatment at 180°C for 1 hour.

[0041] Furthermore, with films having a glass transition temperature below 100°C, such as PET films, the surface smoothness of the base film tends to be impaired after heat treatment at 180°C for 1 hour. During pre-drying, the resin sheet may peel off from the release film, and after main drying, the resin sheet may deform or break due to deformation of the base film.

[0042] Another specific market demand is the reduction of costs associated with release film processing. One way to reduce the cost of release layer processing is to increase the film transport speed and process it at high speed. However, in this invention, increasing the transport speed may lead to deterioration of the winding shape, such as winding misalignment, so the tension during transport must also be increased, which may cause wrinkles in the film during transport. In addition, the shorter time the film stays in the furnace reduces the amount of heat applied to the film, which can lead to insufficient hardening of the release layer due to insufficient drying and blocking of the film roll due to insufficient hardening.

[0043] In this invention, since the glass transition temperature of the resin constituting the base film is 100°C or higher, it is possible to raise the temperature of the drying oven. For example, the present invention avoids the problem that could occur with conventional combinations of base film and release layer, where the increased amount of drying heat made the film prone to wrinkling during transport. Furthermore, because the glass transition temperature of the resin constituting the base film is 100°C or higher, the base film is less likely to wrinkle even when the coating tension or drying temperature is increased, allowing the release film to be processed at high speed, which contributes to cost reduction.

[0044] The water vapor permeability of the base film used in this invention is 1.0 g / m². 2 ·d or more 25.0g / m 2 It is preferable that it be d, 3.0 g / m 2 ·d or more 15.0g / m 2 It is even more preferable that it be d, 5.0 g / m 2 ·d or more 10.0g / m 2 It is most preferable that it be less than or equal to d.

[0045] By keeping the water vapor transmission rate within the above range, when a release layer is formed on the base film, a release film can be formed that is free from unevenness and stickiness and possesses the desired peeling force. 2 - A value of d or higher is preferable because, as described later, when a coating liquid containing a solvent is applied to form a release layer on the base film, the solvent dries efficiently, suppressing unevenness and stickiness on the surface of the release film due to insufficient drying. On the other hand, although the detailed mechanism is not clear, a water vapor transmission rate of 25.0 g / m² is preferable. 2 By having a value of d or less, the solvent does not evaporate rapidly during drying, but evaporates over a certain period of time, which allows the release components in the coating liquid to be efficiently oriented to the surface of the release layer, thereby forming a release film with the desired peeling force. In this invention, the water vapor permeability can be evaluated, for example, by measuring the water vapor transmission rate at a substrate film thickness of 25 μm.

[0046] The Martens hardness (HMT115) of the base film used in this invention is 150 N / mm². 2 More than 400N / mm 2 Preferably, it is 170 N / mm 2 More than 370N / mm 2 It is even more preferable that the following conditions apply: 200 N / mm 2 More than 350N / mm 2 The following is most preferable: By setting the Martens hardness of the base film within the above range, a release layer can be provided on the base film to create a release film, which can then be used as a process film such as a resin sheet. This release film can prevent deformation of the object to be released when it is peeled off.

[0047] The base film has a Martens hardness (HMT115) of 150 N / mm². 2As a result of the above, the elastic modulus of the release film is high, and when the object to be released is peeled from the release film, the release film does not deform following the object to be released. Therefore, excessive stress is not applied to any part of the object to be released, and it can be peeled with a uniform force, preventing deformation of the object to be released. On the other hand, the Martens hardness (HMT115) of the base film is 400 N / mm². 2 The following are preferable because they result in good handling and ease of use.

[0048] (Release layer) The release layer in the present invention is a release layer comprising acrylic resin A and crosslinking agent B, and substantially free of silicone components. For example, a release layer can be formed by curing a release layer forming composition comprising acrylic resin A and crosslinking agent B. In the present invention, acrylic resin A comprises, as constituent units, component A-1 represented by the following general formula (1) and component A-2 represented by the following general formula (2), and in particular, in general formula (1), R1 is (C n H 2n+1 The effects of the present invention can be achieved by setting n to an integer between 5 and 10 (inclusive).

[0049] (Acrylic resin) The release layer in the present invention contains acrylic resin A. Acrylic resin A comprises, as constituent units, component A-1 represented by the following general formula (1) and component A-2 represented by the following general formula (2). In one embodiment, acrylic resin A may be a resin obtained by crosslinking a polymer containing component A-1 and component A-2.

[0050] [ka]

[0051] In general formula (1), R1 is (C n H 2n+1 )(n=an integer between 5 and 10), R3 represents H or CH3. Preferably, n is an integer between 5 and 9, for example, an integer between 6 and 9, or an integer between 6 and 8.

[0052] [ka]

[0053] In general formula (2), R2 is (C m H 2m OH)(m=an integer between 1 and 10) or H, R4 represents H or CH3. In the above formula, for example, m=an integer between 1 and 8, m=an integer between 1 and 6, and m=an integer between 1 and 4.

[0054] When the total mass of component A-1 and component A-2 of the acrylic resin A in the release layer is 100 parts by mass, it is preferable that the mass of A-1 is 30 parts by mass or more. Preferably, the mass of A-1 is 35 parts by mass or more, and may be 40 parts by mass or more.

[0055] A mass of A-1 of 30 parts by mass or more is preferable because it tends to improve the release properties of the release layer. For example, the mass of A-1 may be 90 parts by mass or less, 70 parts by mass or less, or 50 parts by mass or less. By keeping the amount of A-1 component within the above range, the various physical properties of the release layer can be maintained before and after heating.

[0056] Furthermore, for similar reasons, the molar ratio of component A-1 to the total number of moles of component A-1 and component A-2 is preferably 30 mol% or more and 90 mol% or less, more preferably 35 mol% or more and 70 mol% or less, and even more preferably 40 mol% or more and 60 mol% or less. The ratio of copolymer components introduced into acrylic resin A is determined by nuclear magnetic resonance spectroscopy ( 1 H-NMR, 13 This can be confirmed using 1C-NMR (Varian Unity 400, manufactured by Agilent).

[0057] In this invention, although the mechanism has not been analyzed, in general formula (1), R1 is (C n H 2n+1The greater the amount of component A-1 represented by (n=an integer between 5 and 10), the greater the amount of 30 parts by mass, which tends to result in a release film that does not peel off in the pre-drying process but has slight peelability in the post-drying process.

[0058] In particular, the greater the amount of the A-1 component represented by an integer n=6 or greater and n=8 or less in general formula (1), the better the above effect can be achieved.

[0059] In the general formula (1) representing component A-1, R1 is an alkyl group with 5 to 10 carbon atoms (n). Having 5 or more carbon atoms (n) allows component A-1 to exhibit good release properties after the drying process. Furthermore, it suppresses the stickiness of the release layer that may occur with alkyl groups with fewer carbon atoms. On the other hand, when the number of carbon atoms (n) is 10 or less, sufficient wettability of the release layer's film surface can be ensured, and appropriate adhesion can be ensured in the pre-drying process. The number of carbon atoms (n) is preferably 6 to 9, and more preferably 6 to 8. Also, R1 may be linear or branched.

[0060] In the general formula (1) representing component A-1, R3 is either H or CH3, and both are preferred. As a raw material for component A-1, the monomer shown in the following general formula (7) can be used.

[0061] [ka]

[0062] In general formula (7), R1 is (C n H 2n+1 (n = an integer between 5 and 10), R3 represents H or CH3. Preferably, n = 6 or 8.

[0063] Specifically, octyl (meth)acrylate, hexyl (meth)acrylate, and the like can be used as raw materials for component A-1.

[0064] In R2 of general formula (2) representing component A-2, the number of carbon atoms m is 1 or more and 10 or less. When the number of carbon atoms m is 10 or less, it is possible to avoid the crosslinking density of the release layer in the present invention becoming sparse, to suppress the weakening of the cohesive force of the release layer itself, and further, to suppress the increase in peeling force. The number of carbon atoms m is preferably 2 or more and 8 or less, and more preferably 2 or more and 4 or less.

[0065] In the general formula (2) representing component A-2, R4 is either H or CH3, both of which are preferred. As a raw material for component A-2, the monomer represented by the following general formula (8) can be used.

[0066] [ka]

[0067] In general formula (8), R2 is (C m H 2m OH)(m=an integer between 1 and 10) or H, R4 represents H or CH3.

[0068] Specifically, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc., can be used as raw materials for component A-2.

[0069] The acrylic resin A contained in the release layer of the present invention has long-chain alkyl groups, and therefore, the release properties can be controlled by orienting the long-chain alkyl groups contained in the acrylic resin A onto the surface of the release layer. In particular, the acrylic resin A according to the present invention can exhibit good wettability to resin compositions that form resin sheets, for example. Furthermore, the acrylic resin A according to the present invention can provide a release film that does not peel off from the object to be released, such as a resin sheet formed on the release layer, during the pre-drying process, and has slight peelability after the main drying process.

[0070] Acrylic resin A may further contain other copolymer components other than those of general formulas (1) and (2) as constituent units. The other copolymer components are preferably present in 10 mol% or less, more preferably 3 mol% or less, and most preferably 0 mol% in acrylic resin A.

[0071] Other copolymerization components include, for example, alkyl methacrylates such as methyl methacrylate (MMA), alkyl acrylates such as methyl acrylate, and non-(meth)acrylic vinyl monomers.

[0072] The acrylic resin A may be, for example, a random copolymer, a block copolymer, a graft copolymer, or the like.

[0073] The weight-average molecular weight of acrylic resin A is preferably greater than 500, more preferably 10,000 or greater, and even more preferably 20,000 or greater, from the viewpoint of suppressing thermal decomposition during heating. Furthermore, from the viewpoint of coating properties considering the viscosity of the coating solution, the weight-average molecular weight is preferably 200,000 or less, and more preferably 150,000 or less. The weight-average molecular weight can be calculated by known methods, for example, by gel permeation chromatography.

[0074] In this invention, the pre-drying step refers to the state after heating at a temperature of 100°C for 2 minutes, and the post-drying step refers to the state after heating at a temperature of 180°C for 15 minutes. Furthermore, in this invention, "after heating" may refer not only to the state immediately after heating, but also to the state after cooling to below the ambient temperature (for example, below 40°C). Moreover, this drying may be carried out in multiple stages.

[0075] Furthermore, the release layer according to the present invention contains acrylic resin A and is substantially free of silicone components. Therefore, the transfer of silicone components to the object to be released can be suppressed, for example, preventing contamination of the object to be released with silicone, and thus avoiding malfunctions of electronic devices caused by the object to be released. In this specification, "substantially free of silicone components" means that silicone components are not intentionally added to the components that form the release layer. For example, it is possible that a very small amount of silicone composition may be unexpectedly present in the manufacturing process of the release layer. Considering this reality, it is preferable that the amount of silicone components contained in the release layer is less than 0.1 parts by mass per 100 parts by mass of the release layer.

[0076] (Crosslinking agent) The crosslinking agent B used to form the release layer in the present invention can be polyisocyanate, melamine, epoxy, aluminum chelate, titanium chelate, UV-curable resin, or a mixture of two or more of these. Among these, melamine is preferred because the cured film is rigid and has excellent chemical resistance and weather resistance. Crosslinking with aluminum chelate or titanium chelate may be undesirable depending on the application due to the presence of metal components.

[0077] Furthermore, in this invention, by using melamine as a crosslinking agent, the resin sheet can be retained without peeling off the release film during pre-drying, and after drying, the resin sheet can be peeled off the release film without deformation or breakage. Although the detailed mechanism has not been analyzed, in general formula (1), R1 is (C n H 2n+1 It is hypothesized that, under heating conditions such as 180°C for 1 hour, the interaction between component A-1 (where n is an integer between 5 and 10) and the melamine-based crosslinking agent causes hardening shrinkage of the release layer, changing the surface morphology and thus increasing the water contact angle. As a result, it is hypothesized that the resin sheet can be retained without peeling off the release film during pre-drying, and after drying, the resin sheet can be peeled off the release film without deformation or breakage.

[0078] In the present invention, the ratio a / b of the mass of the acrylic resin (a) and the mass of the crosslinking agent (b) contained in the release layer satisfies formula (I).

[0079] (I) 0.001 ≤ a / b ≤ 0.2 In one embodiment, the ratio a / b of the mass of the acrylic resin (a) to the mass of the crosslinking agent (b) is 0.001 or more and 0.2 or less, for example, 0.005 or more and 0.1 or less, and may also be 0.01 or more and 0.05 or less. By setting the ratio a / b of the mass of the acrylic resin (a) to the mass of the crosslinking agent (b) within the above range, the peeling force of the release film can be controlled within the desired range.

[0080] Furthermore, because the release component of acrylic resin A, which is oriented on the surface of the release layer, is fixed by the crosslinking agent, the heavy peeling force after heating is suppressed.

[0081] Furthermore, although the detailed mechanism is not yet clear, we believe that by keeping the ratio a / b of the mass of acrylic resin (a) to the mass of the crosslinking agent (b) within the above range, the acrylic resin segregated on the outermost surface of the release layer is efficiently and sufficiently crosslinked, and for example, even when the release film is heated, the release properties of the release film do not change significantly.

[0082] If the ratio a / b of the mass of acrylic resin (a) to the mass of crosslinking agent (b) is 0.001 or less, the amount of release component of acrylic resin A present on the surface of the release layer will decrease. For example, in a configuration where a resin sheet is used as the material to be released, the peeling force will increase, which may lead to deformation or tearing of the resin sheet.

[0083] Furthermore, although a theoretical analysis has not yet been conducted, if the ratio a / b of the mass of acrylic resin (a) to the mass of the crosslinking agent (b) is 0.2 or higher, the acrylic resin segregated on the outermost surface of the release layer may not be efficiently and sufficiently crosslinked, and for example, it may not exhibit its intended release properties when heated.

[0084] The melamine-based compound used in the release layer of the present invention can be any common compound and is not particularly limited, but it is preferable that it is obtained by condensing melamine and formaldehyde and has one or more triazine rings and one or more methylol groups and / or alkoxymethyl groups in one molecule. Specifically, a compound obtained by dehydrating and condensing a methylolmelamine derivative obtained by condensing melamine and formaldehyde with a lower alcohol such as methyl alcohol, ethyl alcohol, isopropyl alcohol, or butyl alcohol to obtain an ether compound is preferred. Examples of methylolated melamine derivatives include monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, and hexamethylolmelamine. One type or two or more types may be used.

[0085] The melamine used in this invention can also be commercially available. For example, Cymel 300, Cymel 301, Cymel 303LF, Cymel 350, Cymel 370N, Cymel 771, Cymel 325, Cymel 327, Cymel 703, Cymel 712, Cymel 701, Cymel 266, Cymel 267, Cymel 285, Cymel 232, Cymel 235, Cymel 236, Cymel 238, Cymel 272, Cymel 212, Cymel 253, Cymel 254, Cymel 202, Cymel 207 (manufactured by Ornex Japan Co., Ltd.), Nikarac MW-30M, Nikarac MW-30, Nikarac MW-30HM, Nikarac MW-390, Examples include Nikarac MW-100LM, Nikarac MA-1-750LM, Nikarac MW-22, Nikarac MS-21, Nikarac MS-11, Nikarac MW-24A-1, Nikarac MS-001, Nikarac MA-1-002, Nikarac MA-1-730, Nikarac MA-1-750, Nikarac MA-1-708, Nikarac MA-1-706, Nikarac MA-1-042, Nikarac MA-1-035, Nikarac MA-1-45, Nikarac MA-1-43, Nikarac MA-1-417, and Nikarac MA-1-410 (manufactured by Nippon Carbide Co., Ltd.). Among these, full-ether type methylated melamine resin is preferred in terms of curability at low temperatures and in a short time, and adhesion to polyester film. Examples of commercially available products include the Cymel 303LF and the Nikalac MW-30.

[0086] In the present invention, it is preferable to add an acid catalyst to the release layer to promote the crosslinking reaction of the melamine-based compound, and it is preferable to add the acid catalyst to the release layer forming composition, apply it, and cure it. The acid catalyst used is not particularly limited and existing acid catalysts can be used, but it is preferable to use a sulfonic acid-based catalyst.

[0087] As sulfonic acid catalysts, for example, p-toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and trifluoromethanesulfonic acid can be suitably used, but from the viewpoint of reactivity, p-toluenesulfonic acid can be particularly suitably used.

[0088] Sulfonic acid-based catalysts have higher acidity and superior reactivity compared to other acid catalysts such as carboxylic acid-based catalysts, allowing for the processing of the release layer at lower temperatures. This is preferable because it suppresses the decrease in film flatness and deterioration of the winding appearance caused by heat during processing.

[0089] In the present invention, the ratio b / c of ​​the mass (b) of the crosslinking agent contained in the release layer to the acid catalyst (c) satisfies formula (II).

[0090] 5 ≤ b / c ≤ 400 (II) In one embodiment, the ratio b / c of ​​the mass of the crosslinking agent (b) to the acid catalyst (c) is 5 to 400, for example, 10 to 200, or 20 to 100. By setting the ratio b / c of ​​the mass of the crosslinking agent (b) to the acid catalyst (c) within the above range, the peeling force of the release film can be controlled within the desired range.

[0091] A ratio b / c of ​​the mass of the crosslinking agent (b) to the acid catalyst (c) is preferable if it is 400 or less, as this promotes the crosslinking reaction of the melamine compound, accelerates the hardening of the release film, and suppresses stickiness and blocking of the film roll. Furthermore, a ratio b / c of ​​5 or more is preferable if the hardened release film has appropriate adhesion, and if a resin sheet is placed on the release film, this prevents the resin sheet from peeling off at unintended times such as during pre-drying or the transport process.

[0092] The sulfonic acid catalyst used in this invention can also be a commercially available one. Examples of commercially available products include Dryer® 900 (p-toluenesulfonic acid, manufactured by Hitachi Chemical Co., Ltd.), NACURE® DNNDSA series (dinonylnaphthalenedisulfonic acid, manufactured by Kusumoto Chemical Co., Ltd.), NACURE® DNNSA series (dinonylnaphthalene (mono)sulfonic acid, manufactured by Kusumoto Chemical Co., Ltd.), NACURE® DDBSA series (dodecylbenzenesulfonic acid, manufactured by Kusumoto Chemical Co., Ltd.), and NACURE® p-TSA series (p-toluenesulfonic acid, manufactured by Kusumoto Chemical Co., Ltd.).

[0093] In the release layer of the present invention, additives such as adhesion enhancers and antistatic agents may be added, as long as they do not hinder the effects of the present invention. Furthermore, in order to improve adhesion to the base film, it is also preferable to pre-treat the surface of the polyester film with an anchor coat, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc., before applying the release coating layer.

[0094] The thickness of the release layer is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.05 μm or more and 1 μm or less. If the thickness of the release layer is less than 0.01 μm, it is difficult to form the release layer uniformly, and the release force may become unstable. On the other hand, if the thickness of the release layer exceeds 10 μm, the proportion of recycled material used will be low, which is uneconomical and therefore undesirable.

[0095] The average surface roughness (Sa) of the release layer region is preferably in the range of 1 to 50 nm, and more preferably 2 to 30 nm. The maximum protrusion height (P) of the surface on which the release layer is laminated of the base film used in the present invention is preferably 2 μm or less, and more preferably 1.5 μm or less. If Sa is 50 nm or less and P is 2 μm or less, thickness unevenness of the release layer and the smoothness of the surface of the release layer can be kept constant, and the possibility of tearing starting from a thin part when the release object is peeled off from the release film can be suppressed.

[0096] Furthermore, the average surface roughness (Sa) and maximum protrusion height (P) of the region preferably change by 20% or less before and after heating, more preferably by 10% or less, and even more preferably by 5% or less. If the change rate of the average surface roughness (Sa) and maximum protrusion height (P) of the region before and after heating is 20% or less, the adhesion area between the release layer and the object to be released increases after heating, and the possibility of excessive delamination when peeling the object to be released from the release layer due to the anchoring effect is low, which is preferable.

[0097] In the present invention, the method for forming the release coating layer is not particularly limited. A coating solution containing a dissolved or dispersed release resin is applied to one side of a base film, the solvent is removed by drying, and then the film is heated, heat-cured, or ultraviolet-cured. In this case, the drying temperature during solvent drying or heat curing is preferably 180°C or lower, more preferably 160°C or lower, and most preferably 140°C or lower. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, and even more preferably 10 seconds or less. When the temperature is 180°C or lower, the flatness of the film is maintained, and there is little risk of causing unevenness in the thickness of the release layer, which is preferable. When the temperature is 140°C or lower, the film can be processed without impairing the flatness of the film, and the risk of causing unevenness in the thickness of the release layer is further reduced, which is particularly preferable.

[0098] In the present invention, the coating liquid used when applying the release coating layer is not particularly limited, but it is preferable to add a solvent with a boiling point of 70°C or higher. Adding a solvent with a boiling point of 70°C or higher prevents bumping during drying, levels the coating film, and improves the flatness of the coating film surface after drying. The amount of solvent added is preferably about 50 to 99% by mass of the total coating liquid.

[0099] Any known coating method can be applied to the above coating liquid. For example, conventional methods such as roll coating methods including gravure coating and reverse coating, bar coating methods such as wire bar coating, die coating, spray coating, and air knife coating can be used.

[0100] The release film obtained in this invention preferably has a tape peeling force within the range shown below.

[0101] The release film obtained in this invention may have a tape peeling force of 5,000 mN / 50 mm to 15,000 mN / 50 mm at a peeling speed of 300 mm / min. For example, it may be 6,000 mN / 50 mm to 13,000 mN / 50 mm, 7,500 mN / 50 mm to 12,000 mN / 50 mm, or 8,000 mN / 50 mm to 12,000 mN / 50 mm. Although it should not be interpreted as being limited to a specific theory, in this invention, the tape peeling force in the above range can be derived by setting the ratio a / b of the mass of the acrylic resin (a) to the mass of the crosslinking agent (b) to be within the range of 0.001 to 0.2.

[0102] Within the above range, it is preferable that the tape peeling force can be removed without deformation or tearing when forming a resin sheet, for example. A tape peeling force of 5000 mN / 50 mm or more is preferable because it reduces the possibility of peeling at unintended times, such as during the pre-drying process of the resin sheet. Furthermore, a tape peeling force of 15000 mN / 50 mm or less is preferable because it reduces the possibility of deformation of the molded object when it is peeled off.

[0103] The tape peeling force refers to the tape peeling force at a peeling speed of 300 mm / min., and can be used to evaluate the peeling force when peeling off a release object, such as an adhesive (for example, an acrylic adhesive tape (manufactured by Nitto Denko, No. 31B)), placed on the release layer according to the present invention. Furthermore, the tape peeling force can be measured under room temperature (25°C) conditions.

[0104] The release film obtained in this invention preferably has a water contact angle within the following range.

[0105] The release film obtained in the present invention preferably has a water contact angle of 50° to 80° on the surface of the release layer, and more preferably 60° to 75°.

[0106] Within the above range, it is preferable that the resin sheet can be peeled off without deformation or tearing, for example. A water contact angle of 80° or less is preferable because there is a low possibility of peeling off at unintended timings, such as during the pre-drying process of the resin sheet. Furthermore, a water contact angle of 50° or more is preferable because there is a low possibility of deformation of the molded object when it is peeled off.

[0107] The above water contact angle is a numerical range measured at room temperature and corresponds to the water contact angle (β) of the release layer surface before heating, as described later.

[0108] In the present invention, it is preferable that the water contact angle (α) of the surface of the release layer after heating at 180°C for 1 hour and the water contact angle (β) of the surface of the release layer before heating satisfy the following formula (1).

[0109] α>β (1)

[0110] In this invention, the water contact angle (α) of the release layer surface after heating refers to the water contact angle measured after heating the release film at 180°C for 1 hour.

[0111] In the present invention, by performing the drying temperature when forming the release layer on the base film under the conditions described herein, equation (1) relating to the water contact angle can be satisfied. Furthermore, the release layer in the present invention can be used as a release film when the release layer is formed on the base film. However, as a feature of the present invention, the inventors have found that, for example, when using the release film in the present invention as a process film and applying heat treatment during the process of forming a resin sheet, the hardening of the release film can be accelerated and the surface morphology of the release layer can be controlled.

[0112] The inventors have found that the peelability of the release layer can be changed after the production of the release film and during the resin sheet formation process, and that the relationship with the water contact angle, expressed in equation (1), can be used as an indicator.

[0113] Furthermore, due to the relationship shown in formula (1) above, at room temperature, the resin sheet forming composition or the film-like resin sheet precursor can adhere closely to the release layer on the release film, and as heating occurs, the adhesion of the resin sheet during manufacturing is maintained, and the molded object can be peeled off smoothly while suppressing deformation of the molded object.

[0114] Thus, during heat treatment, the hardening of the release film progresses further, causing hardening shrinkage of the release layer and a change in surface morphology, which increases the water contact angle. As a result, a small gap is created between the release film and the resin sheet, reducing the likelihood of deformation of the object to be released when it is peeled off.

[0115] Furthermore, heating does not simply increase the water contact angle; it is necessary to satisfy equation (1) relating to the water contact angle, and the present invention can have such a relationship. The heat treatment temperature of the resin sheet may be, for example, 180°C for 1 hour.

[0116] In one embodiment, the difference |(α)-(β)| between the water contact angle (α) of the surface of the release layer after heating at 180°C for 1 hour and the water contact angle (β) of the release film before heating is 1.3 or greater, for example, 1.35 or greater. The upper limit may be, for example, 6.0 or less, or 5.0 or less.

[0117] Although the detailed mechanism has not been explored, under these conditions, hardening in the release film progresses further during heat treatment, causing hardening shrinkage of the release layer and a change in surface morphology, which increases the water contact angle. As a result, a small gap is created between the release film and the resin sheet, reducing the possibility of deformation of the object to be released when it is peeled off. Furthermore, it is presumed that the surface morphology at the nanoscale does not change significantly, and the effects of the present invention can be more effectively demonstrated in release films for the manufacture of electronic components such as ceramic capacitors, release films for resin sheet molding containing epoxy resins, release films for forming all-solid-state batteries, and release films for resin sheet molding having a urethane structure. Moreover, it becomes possible to peel off the object to be released without damaging it.

[0118] The release film obtained in this invention has a Martens hardness (HMT115) of 200 N / mm² in the release layer. 2 More than 1500N / mm 2 Preferably, the following: 300 N / mm 2 More than 1250N / mm 2 It is even more preferable that the following conditions are met: 350 N / mm 2 More than 1000N / mm 2 The following is most preferable:

[0119] By setting the Martens hardness (HMT115) of the release layer within the above range, it is possible to provide a release film that prevents deformation of the object to be released when it is peeled off, when the release film is used as a process film such as a resin sheet.

[0120] The Martens hardness (HMT115) of the release layer is 200 N / mm². 2 As a result of the above, when the object to be released is peeled off the release film, the release layer does not deform in accordance with the object to be released. Therefore, excessive stress is not applied to any part of the object to be released, allowing for peeling with uniform force and preventing deformation of the object to be released.

[0121] The release film obtained in this invention, by setting the Martens hardness of the base film and the release layer within the aforementioned range and combining them, allows the resin sheet to remain attached to the release film during pre-drying and to be removed from the release film after main drying without deformation or breakage of the resin sheet. Furthermore, because of this relationship, even if the release film is thin, it is possible to obtain a release film that does not deform during the heat treatment process, and does not cause deformation or tearing of the resin sheet.

[0122] In the present invention, it is preferable that the release film obtained does not cause the resin sheet to peel off the release film when the resin sheet peeling force is measured under pre-drying conditions. When the resin sheet does not peel off the release film, for example, when the resin sheet is formed, there is a low possibility of it peeling off at an unintended timing such as during the pre-drying process, which is preferable.

[0123] The release film obtained in this invention preferably has a peeling force of 1000 mN / 50 mm or less, more preferably 500 mN / 50 mm or less, and most preferably 300 mN / 50 mm or less, when measured under the post-drying process conditions. It may also have a peeling force of 5 mN / 50 mm or more, or 10 mN / 50 mm or more.

[0124] Within the above range, it is preferable that the molded object is less likely to deform when peeled off after heating in the post-drying process, etc.

[0125] In this invention, the pre-drying step refers to the state after heating at a temperature of 100°C for 2 minutes, and the post-drying step refers to the state after heating at a temperature of 180°C for 15 minutes. Furthermore, in this invention, "after heating" may refer not only to the state immediately after heating, but also to the state after cooling to below the ambient temperature (for example, below 40°C).

[0126] The resin sheet peeling force refers to the peeling force of the resin sheet at a peeling speed of 300 mm / min., and can be used to evaluate the peeling force when peeling off a mold-release object, such as a resin sheet (for example, a resin sheet formed by curing epoxy resin, etc.), placed on the release layer according to the present invention. Furthermore, the tape peeling force can be measured under room temperature (25°C) conditions.

[0127] In the present invention, a laminated film can be obtained by providing a resin layer on at least one side of a release film. The laminated film can be obtained, for example, by applying a resin composition to at least one surface of the release film of the present invention, drying it as necessary, and forming a resin layer on at least one side of the substrate. For example, the resin layer can also be provided on the side of the release layer opposite to the substrate film.

[0128] The present invention can be applied to other uses such as battery components, adhesive layer protection (protection for OCA (Optical Clear Adhesive), protection for adhesive tapes, etc.), separators for transdermal patch medications in the medical field, process films used in the manufacturing process of semiconductor-related components such as circuit boards, process films used in the manufacturing process of electronic components such as ceramic capacitors, and protection of image display components. Similar effects can be expected.

[0129] In one embodiment, the release film of the present invention can exhibit the effects of the present invention more effectively in release films for manufacturing electronic components such as ceramic capacitors, release films for molding resin sheets containing epoxy resins, release films for forming all-solid-state batteries, and release films for molding resin sheets having a urethane structure, depending on the properties of the components contained in the release layer. [Examples]

[0130] The present invention will be described in more detail below using examples, but the present invention is not limited in any way by these examples. The characteristic values ​​used in the present invention were evaluated using the following method.

[0131] <Rating> (Tape peeling strength) Adhesive tape ("31B" manufactured by Nitto Denko Corporation) was attached to the surface of the release film, and after being pressed with a pressure roller with a linear pressure of 5 kgf / mm, it was left for 20 hours under conditions of 22°C and 60% humidity. The release film with the adhesive tape attached was cut into strips 25 mm wide and 150 mm long. One end of the adhesive tape was fixed, and one end of the release film was supported, and the release film side was pulled at a speed of 300 mm / min. The T-shaped peel strength was measured. A tensile testing machine ("AUTOGRAPHAG-A-1" manufactured by Shimadzu Corporation) was used for the measurement.

[0132] (Water contact angle before heating) Using a contact angle meter (a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Science Co., Ltd.), the contact angle of water in contact with the surface of the release layer was measured under conditions of 22°C and 60% RH.

[0133] (Water contact angle after heating) Using a contact angle meter (Kyowa Interface Science Co., Ltd.'s "Fully Automatic Contact Angle Meter DM-701"), the release film was placed in an oven set to 180°C, and after 1 hour, it was removed from the oven and allowed to stand until it reached room temperature. The contact angle of water in contact with the surface of the release layer was then measured under conditions of 22°C and 60% RH.

[0134] (Martens hardness of the base film) The base film was cut to a size of 0.5 mm x 0.5 mm, fixed onto glass using adhesive tape, and a load-unload test was performed using a dynamic ultramicrohardness tester (DUH-211S, Shimadzu Corporation). From this measurement, the Martens hardness (HMT115) was determined using the following formula (average value for n=10). HMT115 = F / (26.43 × h 2 )(N / mm 2 ) (F: Load (N), h: Indentation depth (mm)) (Measurement conditions) Indenter used: Diamond triangular pyramidal indenter (angle between edges: 115°) Measurement mode: Load-unload test Test force: 500mN Minimum test force: 1.96 mN Load speed: 7.0mN / sec Load holding time: 5sec Unloading holding time: 5sec Measurement environment: 25±1℃, 65±5%RH Number of measurements: 10

[0135] (Martens hardness of the release layer) A mixed composition of resin and crosslinking agent was prepared in a mixed solvent of 50% by mass of toluene and 50% by mass of MEK (at 25°C) to a solid content concentration of 20% by mass. A glass slide sample was prepared by applying the coating solution to the surface of a glass slide using a wire bar, resulting in a coating layer thickness of 3.0 μm. The glass slide sample was heat-treated by standing it in a hot air circulating oven set at 130°C for 5 minutes and then removing it.

[0136] The surface of the obtained samples was subjected to a load-unload test using a dynamic ultramicrohardness tester (DUH-211S, Shimadzu Corporation). From this measurement, the Martens hardness (HMT115) was determined using the following formula (average value for n=10). HMT115 = F / (26.43 × h 2 )(N / mm 2 ) (F: Load (N), h: Indentation depth (mm)) (Measurement conditions) Indenter used: Diamond triangular pyramidal indenter (angle between edges: 115°) Measurement mode: Indentation depth setting load-unload test Minimum test force: 0.002 mN Load speed: 0.0150mN / sec Load holding time: 3sec Unloading holding time: 3sec Indentation depth: 0.1 μm Measurement environment: 25±1℃, 65±5%RH Number of measurements: 10

[0137] (Resin sheet peeling force under pre-drying conditions: PF1) An epoxy resin (Mitsubishi Chemical Corporation, jER828) was used as the resin, and a phenol resin (DIC Corporation, phenol novolac, TD-2090-60M, 60% solids MEK solution) was used as a crosslinking agent. These were mixed in a 1:2 ratio, and MEK was added to adjust the solids concentration to 60.0% by mass to obtain a resin coating solution. The obtained resin coating solution was applied to the surface of the release film using an applicator, and then dried at 100°C for 2 minutes to form a release film with a resin layer with a thickness of 50.0 μm.

[0138] Adhesive tape ("31B" manufactured by Nitto Denko Corporation) was attached to the resin surface of the obtained resin-coated release film, and the resin-coated release film with the adhesive tape attached was cut into strips 25 mm wide and 150 mm long. One end of the adhesive tape was fixed, and one end of the resin-coated release film was supported on it. The resin-coated release film side was pulled at a speed of 300 mm / min., and the T-shaped peel strength was measured. A tensile testing machine ("AUTOGRAPHAG-A-1" manufactured by Shimadzu Corporation) was used for the measurement.

[0139] (Resin sheet peeling force under post-drying process conditions: PF2) Except for changing the drying conditions to heating at 180°C for 15 minutes, the measurement was performed in the same manner as (resin release force in the previous drying process).

[0140] (Film flatness) A 1m wide x 10m long film sample, cut from the center of the release film's width, was placed under a three-wavelength fluorescent lamp so that the width of the film sample was parallel to the axis of the elongated three-wavelength fluorescent lamp. The reflection of the three-wavelength fluorescent lamp on the film sample was then visually inspected. If the film sample had heat wrinkles after being heated at 180°C for 15 minutes, the image of the three-wavelength fluorescent lamp reflected on the film sample would be distorted or intermittent. A nearly straight image of the three-wavelength fluorescent lamp was judged as ○. A slightly distorted and / or intermittent image was judged as △.

[0141] (Glass transition temperature) The glass transition temperature (extracorporeal start temperature) of the polymer was measured using a DSC (EXSTAR6000, Seiko Instruments Corporation) with a sample volume of 10 mg and a heating rate of 20 °C / min.

[0142] (Example 1) (Preparation of acrylic resin (A1) and release layer coating liquid) Hexyl acrylate (CH2=C(H)COOC6H 13), hydroxyethyl acrylate (CH2=C(H)COOC2H4OH) was mixed in a molar ratio of 50:50, toluene was added to bring the solid content concentration to 40% by mass, and under a nitrogen atmosphere, 0.5 mol% of azobisisobutyronitrile (AIBN) was added to copolymerize and obtain acrylic resin (A1).

[0143] Acrylic resin (A1), melamine resin (Nikarac MW-30, manufactured by Nippon Carbide Co., Ltd.) as crosslinking agent B, and p-toluenesulfonic acid (Dryer #900, manufactured by Hitachi Chemical Polymer Co., Ltd.) as a curing catalyst were added in the proportions shown in Table 1. A solvent (toluene / MEK = 50 / 50: mass ratio) was then added to adjust the solid content concentration to 12.0% by mass, thereby obtaining a release layer coating liquid.

[0144] A polyethylene naphthalate film (manufactured by Toyobo Co., Ltd., Q5100, thickness: 25 μm, average surface roughness (Sa): 0.006 μm, haze: 12.6%) was used as the base film.

[0145] (Formation of release layer) The obtained release layer coating solution was applied to the substrate film using a gravure coater, and then dried at 130°C for 30 seconds to form a release layer with a thickness of 0.3 μm. The obtained release film was then evaluated according to the above criteria.

[0146] (Example 2) (Preparation of acrylic resin (A2) and release layer coating liquid) Octyl acrylate (CH2=C(H)COOC8H) 17 ) and hydroxyethyl acrylate (CH2=C(H)COOC2H4OH) were mixed in a molar ratio of 30:70, toluene was added to bring the solid content concentration to 40% by mass, and under a nitrogen atmosphere, 0.5 mol% azobisisobutyronitrile (AIBN) was added to copolymerize and obtain acrylic resin (A2).

[0147] The release layer was formed using the same procedure as in Example 1, except that the acrylic resin was changed to A2. The obtained release film was then evaluated according to the above criteria.

[0148] (Examples 3-10) The release layer was formed using the same procedure as in Example 1, except that the composition was changed to that shown in Table 1. The obtained release film was then evaluated according to the above criteria.

[0149] (Comparative Example 1) (Preparation of acrylic resin (A3) and release layer coating liquid) Butyl acrylate (CH2=C(H)COOC4H9) was copolymerized with toluene to a solid content concentration of 40% by mass, and 0.5 mol% azobisisobutyronitrile (AIBN) was added under a nitrogen atmosphere to obtain acrylic resin (A3).

[0150] The release layer was formed using the same procedure as in Example 1, except that the acrylic resin was changed to A3. The obtained release film was then evaluated according to the above criteria.

[0151] (Comparative Example 2) (Preparation of acrylic resin (A4) and release layer coating liquid) Stearyl acrylate (CH2=C(H)COOC 12 H 25 Toluene was added to the mixture to a solid content concentration of 40% by mass, and under a nitrogen atmosphere, 0.5 mol% azobisisobutyronitrile (AIBN) was added and copolymerized to obtain acrylic resin (A4).

[0152] The release layer was formed using the same procedure as in Example 1, except that the acrylic resin was changed to A4. The obtained release film was then evaluated according to the above criteria.

[0153] (Comparative Example 3) (Preparation of acrylic resin (A5) and release layer coating liquid) Stearyl acrylate (CH2=C(H)COOC 18 H 37 Toluene was added to the mixture to a solid content concentration of 40% by mass, and under a nitrogen atmosphere, 0.5 mol% azobisisobutyronitrile (AIBN) was added and copolymerized to obtain acrylic resin (A5).

[0154] The release layer was formed using the same procedure as in Example 1, except that the acrylic resin was changed to A5. The obtained release film was then evaluated according to the above criteria.

[0155] (Comparative Example 4) A polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., E5100, thickness: 38 μm, average surface roughness (Sa): 0.0365 μm (corona-treated surface), maximum cross-sectional height (St): 3.72, haze: 3.7%) was used as the base film, and a release layer was formed in the same procedure as in Example 1, except that a release layer coating liquid was applied to the corona-treated surface. The obtained release film was evaluated according to the above criteria.

[0156] Tables 1 and 2 describe the various film formation conditions and evaluation results for the examples and comparative examples.

[0157] [Table 1]

[0158] [Table 2]

[0159] <Evaluation Results> According to embodiments of the present invention, a release film can be provided that prevents the resin sheet from peeling off the release film during pre-drying, and allows the resin sheet to be peeled off the release film without deformation or breakage after drying. Furthermore, when heat or pressure is applied to the release film, the release film of the present invention can suppress deformation, wrinkles, etc., even if the release film is thin.

[0160] On the other hand, in Comparative Example 1, since n=4 for R1 in component A-1 of acrylic resin A, the tape peeling force increased significantly, and although the resin sheet could not be peeled off under pre-drying conditions, it could not be peeled off even under post-drying conditions. In Comparative Example 2, since n=12 for R1 in component A-1 of acrylic resin A, the tape peeling force decreased, and the resin sheet partially peeled off under pre-drying conditions. In Comparative Example 3, since n=18 for R1 in component A-1 of acrylic resin A, the tape peeling force decreased significantly, and the resin sheet peeled off under pre-drying conditions. In Comparative Example 4, since the base film used was PET (glass transition temperature: 80°C) that does not contain naphthalenedicarboxylic acid, it was confirmed that the flatness of the film was slightly impaired compared to the present invention.

[0161] The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments described above, and all modifications within the scope of the claims are intended to be included in the meaning of equivalents and within the scope. [Industrial applicability]

[0162] The present invention provides a release film that prevents the resin sheet from peeling off the release film during pre-drying, allows the resin sheet to be peeled off the release film after drying without deformation or tearing, and prevents deformation or tearing of the release film during the heat process even when the release film is thin, and also prevents deformation or tearing of the resin sheet.

Claims

1. A release film having a base film and a release layer, The aforementioned release layer contains acrylic resin A and a melamine-based crosslinking agent B. The ratio a / b of the mass of acrylic resin A (a) to the mass of melamine-based crosslinking agent (b) satisfies formula (I): 0.001 ≤ a / b ≤ 0.

05. The acrylic resin A comprises, as constituent units, component A-1 represented by the following general formula (1) and component A-2 represented by the following general formula (2). The amount of silicone component contained in the release layer is less than 0.1 parts by mass per 100 parts by mass of the release layer. A release film in which the glass transition temperature of the resin constituting the base film is 100°C or higher. 【Chemistry 1】 (In general formula (1), R １ is (C ｎ H ２ｎ＋１ ) (n = an integer between 5 and 10), R ３ is H or CH ３ (This indicates...) 【Chemistry 2】 (In the general formula (2), R ２ is (C ｍ H ２ｍ OH) (an integer where m = 1 or more and 10 or less) or H, R ４ is H or CH ３ .)

2. The release film according to claim 1, wherein the molar ratio of component A-1 to the total number of moles of component A-1 and component A-2 is 30 mol% or more and 90 mol% or less.

3. The release film according to claim 1 or 2, wherein the tape peeling force at a release layer peeling speed of 300 mm / min is 5000 mN / 50 mm or more and 15000 mN / 50 mm or less.

4. The Martens hardness of the aforementioned base film is 150 N / mm². ２ The release film according to claim 1 or 2.

5. The release film according to claim 1 or 2, wherein the water contact angle (α) of the release layer surface after heating at 180°C for 1 hour and the water contact angle (β) of the release layer surface before heating satisfy the following formula (1). α＞β （１）

6. The release film according to claim 1 or 2, wherein the base film contains a polyester resin having structural units derived from naphthalenedicarboxylic acid as a dicarboxylic acid component.

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