Release film

Abstract

Provided is 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 drying. 【Solution means】A release film having a base film and a release layer, The release layer contains an acrylic resin (A) and a crosslinking agent (B), The acrylic resin (A) contains the A-1 component and the A-2 component described in the specification, It is a release film in which the release layer substantially does not contain a silicone component and the release layer is laminated on the base film, The glass transition point of the resin constituting the base film is 100°C or higher, The pencil hardness of the base film is B or higher, The pencil hardness (H2) of the release film after heating at 180°C for 1 hour is HB or higher, A release film in which the pencil hardness (H2) of the release film after heating at 180°C for 1 hour and the pencil hardness (H1) of the release film before heating satisfy the following formula (1). H2 > H1 Formula (1)

Description

[Technical Field]

[0001] This invention relates to a release film for molding resin sheets, and more particularly to a release film for molding resin sheets 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. To improve these issues, release films with strong peeling force have been proposed. However, while the resin sheet does not peel off the process film during the pre-drying process, the resin sheet also cannot be peeled off the process film after the main drying process, resulting in a problem where the original purpose cannot be achieved.

[0005] Furthermore, from the perspective of improving productivity, there is a demand for thinning of both the resin sheet and the release film. However, when the release film is thin, when heat and pressure are applied, the release film deforms or wrinkles due to the heat, making it impossible to maintain a consistent peeling force when separating the resin sheet from the release film, which can cause deformation or tearing of the resin sheet.

[0006] Thus, existing release films have problems in that they cannot fully perform as intended, and improvements are needed.

[0007] The present invention solves the above problems by providing 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 without deformation or breakage after main drying, and prevents deformation or tearing of the release film during the heat process even when the release film is thin, and prevents deformation or tearing of the resin sheet. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventors of the present invention found that the above objective can be achieved by a release film having the following configuration, and thus completed the present invention.

[0009] In other words, the present invention consists of the following configuration. [1] A release film having a base film and a release layer, The release layer comprises an acrylic resin (A) and a crosslinking agent (B). The acrylic resin (A) contains component A-1 represented by the following chemical formula (Chemical Formula 1) and component A-2 represented by (Chemical Formula 2). The release layer substantially does not contain a silicone component, and is a release film in which the release layer is laminated on a base film, the glass transition point of the resin constituting the base film is 100°C or higher, the pencil hardness of the base film is B or higher, the pencil hardness (H2) of the release film after heating at 180°C for 1 hour is HB or higher, a release film in which the pencil hardness (H2) of the release film after heating at 180°C for 1 hour and the pencil hardness (H1) of the release film before heating satisfy the following formula (1). H2 > H1 Formula (1)

[0010]

Chemical formula

[0011]

Chemical formula

[0012] The present invention provides a release film 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 main drying. Furthermore, when heat and pressure are applied to the release film, the release film of the present invention can suppress deformation and wrinkles even if the release film is thin. Moreover, for example, the peeling force when peeling a resin sheet from the release film can be kept constant, preventing deformation and tearing of the resin sheet, so resin sheets manufactured using the release film of the present invention can be applied to electronic components and the like. [Modes for carrying out the invention]

[0013] As a result of diligent research, the inventors have concluded that the present invention is a release film comprising a base film and a release layer, The release layer comprises an acrylic resin (A) and a crosslinking agent (B). The acrylic resin (A) contains component A-1 represented by the following chemical formula (Chemical Formula 1) and component A-2 represented by (Chemical Formula 2). The aforementioned release layer substantially does not contain any silicone components, and the release layer is laminated on a base film, The glass transition temperature of the resin constituting the base film is 100°C or higher. The pencil hardness of the base film is B or higher. The pencil hardness (H2) of the release film after heating at 180°C for 1 hour is HB or higher. A release film whose pencil hardness (H2) after heating at 180°C for 1 hour and the pencil hardness (H1) of the release film before heating satisfy the following equation (1). H2 > H1 Equation (1)

[0014] [ka] In chemical formula (1), R1 represents (CnH2n+1) (n = an integer between 5 and 10), and R4 represents H or CH3.

[0015] [ka] In chemical formula (2), R2 represents (CmH2mOH) (m = an integer between 1 and 10) or H, and R4 represents H or CH3.

[0016] (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.

[0017] 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. Furthermore, by laminating the base film of the present invention 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 material during heating and the thermal shrinkage and expansion properties of the release layer during heating. 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 of 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 the release layer can be well-balanced. 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. 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.

[0018] As the base film, known base materials can be used. For example, resin films formed from polyester such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, and polyimides can be used as the base material. Polyester films are particularly preferred from the viewpoint of cost and productivity, and polyethylene terephthalate and polyethylene naphthalate films are even more preferred. In one embodiment, the base film is a film cured from a composition containing a polyester resin, wherein the polyester resin contains naphthalenedicarboxylic acid as a 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 a 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. In one embodiment, a composition containing a polyester resin comprises naphthalenedicarboxylic acid as the main component of the dicarboxylic acid component.

[0019] The thickness of the base material is preferably 10 μm to 188 μm, and more preferably 16 μm to 100 μm. A base material thickness of 10 μm or more suppresses deformation due to heat during base material production, processing, and molding. On the other hand, a base material thickness of 188 μm or less allows for the reduction of the amount of base material to be discarded after use while still meeting the required physical properties of the base material, thereby reducing the burden on the environment. Furthermore, if the thickness of the base material is 100 μm or less, it is preferable because it allows for the production of longer rolls in a single production run, improving productivity from the standpoint of reducing base material loss and improving transportability.

[0020] A coating for improved adhesion may be placed between the substrate and the release layer. Additionally, a coating for properties such as slipperiness, heat resistance, and antistatic properties may be applied to the surface of the substrate opposite to the surface where the release layer is placed.

[0021] 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.

[0022] 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.

[0023] 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 performance of the release film, and thus the release film tends to exhibit desirable heat resistance. Furthermore, it tends to exhibit a greater interaction with the release layer of the present invention.

[0024] The base film in this invention can be made from recycled polyester film scraps or 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 of this invention allows for the proper collection, processing, and reuse of polyester films used in various applications. 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.

[0025] For example, the substrate of 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 described average surface roughness (Sa) and maximum protrusion height (P) of the surface on which the release layer of the substrate film is laminated. In one embodiment, the substrate has a surface layer that is substantially free of inorganic particles, and a release layer may be laminated on this surface layer.

[0026] 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. 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. 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 material.

[0027] 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. 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.

[0028] In the present invention, the pencil hardness of the base film is preferably B or higher. When the pencil hardness is B 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 maintains its flatness, so a resin sheet of uniform thickness can be formed, which is preferable. 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. Furthermore, with films having a pencil hardness of B or less, such as PET films with a pencil hardness less than B, 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 material. Note that a pencil hardness less than B means that the film is soft, such as having a pencil hardness of 2B or 3B.

[0029] 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. By setting the water vapor transmission rate within the above range, when a release layer is formed on the base film, a release film having no unevenness or stickiness and having a target release force can be formed. When the water vapor transmission rate is 1.0 g / m 2 ·d or more, as described later, when forming a release layer on the base film, when applying a coating liquid containing a solvent, the drying of the solvent proceeds efficiently, and it is preferable to suppress unevenness or stickiness on the surface of the release film due to insufficient drying. On the other hand, although the detailed mechanism is not clear, when the water vapor transmission rate is 25.0 g / m 2 ·d or less, the solvent does not volatilize rapidly during drying and volatilizes over a certain period of time, so that the release components in the coating liquid can be efficiently oriented on the surface layer of the release layer, and it is considered that a release film having a target release force can be formed. The water vapor permeability in the present invention can be evaluated, for example, with respect to the water vapor transmission rate measured at a base film thickness of 25 μm.

[0030] The Martens hardness (HMT115) of the base film used in the present invention is 150 N / mm 2 or more and 400 N / mm 2 or less, preferably 170 N / mm 2 or more and 370 N / mm 2 )]]or less, more preferably 200 N / mm 2 or more and 350 N / mm 2 or less is most preferable. By setting the Martens hardness of the base film within the above range, when a release layer is provided on the base film to produce a release film and used as a process paper such as a resin sheet, it is possible to provide a release film that can prevent deformation of the release object when the release object is peeled off. When the Martens hardness (HMT115) of the base film is 150 N / mm 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.

[0031] (Release layer) The release layer in the present invention comprises an acrylic resin (A) and a crosslinking agent (B), and is substantially free of silicone components. For example, a release layer can be formed by curing a release layer forming composition comprising an acrylic resin (A) and a crosslinking agent (B). In the present invention, the acrylic resin (A) comprises component A-1 represented by the following chemical formula (Chemical Formula 1) and component A-2 represented by (Chemical Formula 2), and in particular, the effects of the present invention can be achieved by having R1 in chemical formula (1) be (CnH2n+1) (n=an integer between 5 and 10).

[0032] (Acrylic resin) The release layer of the present invention contains acrylic resin (A). Furthermore, it is preferable that the acrylic resin (A) contained in the release layer of the present invention has a long-chain alkyl group. The release properties can be controlled by orienting the long-chain alkyl group contained in the acrylic resin (A) on the surface of the release layer. In particular, the acrylic resin (A) according to the present invention can exhibit good wettability to, for example, a resin composition that forms a resin sheet. Moreover, the acrylic resin (A) according to the present invention can provide a release layer 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, but has slight peelability after the main drying process. The acrylic resin of the present invention may further include a methacrylic resin, for example, a polymer of methyl methacrylate (MMA), or a copolymer with an acrylic acid ester (acrylate). Furthermore, for example, the molecular weight of the acrylic resin (A) is preferably greater than 500. 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.

[0033] Furthermore, the release layer according to the present invention contains an 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 the object to be released from being contaminated 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.

[0034] The acrylic resin (A) may be, for example, an acrylic polymer copolymerized with long-chain alkyl acrylates, a graft polymer with long-chain alkyl grafts, or a block polymer with long-chain alkyl grafts at its ends.

[0035] The acrylic resin (A) comprises component A-1 represented by the following formula (1) and component A-2 represented by the following formula (2). In one embodiment, the acrylic resin (A) may be a resin obtained by crosslinking a polymer containing component A-1 and component A-2.

[0036] [ka]

[0037] In chemical formula (1), R1 represents (CnH2n+1) (n = an integer between 5 and 10), and R4 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.

[0038] [ka]

[0039] In chemical formula (2), R2 represents (CmH2mOH) (m = an integer between 1 and 10) or H, and 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.

[0040] 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 exceeds 30 parts by mass. Preferably, the mass of A-1 is 30 parts by mass or more, and may be 40 parts by mass or more. It is preferable that the mass of A-1 exceeds 30 parts by mass, as this tends to improve the release properties of the mold release layer. For example, the mass of A-1 is 90 parts by mass or less, may be 70 parts by mass or less, or may be 50 parts by mass or less. By keeping the amount of component A-1 within the above range, the various physical properties of the release layer can be maintained before and after heating. In this invention, although the mechanism has not been analyzed, the more than 30 parts by mass of component A-1, represented by chemical formula (1) where R1 is (CnH2n+1) (n=an integer between 5 and 10), the more likely it is to provide a release layer film that does not peel off in the pre-drying process but has slight peelability in the post-drying process. In particular, the greater the amount of component A-1 represented by an integer n=6 or greater and n=8 or less in chemical formula (1), the better the above effect can be achieved.

[0041] In chemical formula (1) representing component A-1, R1 is an alkyl group with 5 to 10 carbon atoms. Having 5 or more carbon atoms 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 due to 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. A carbon number n of 6 to 9 is preferred, and 6 to 8 is more preferred. Furthermore, R1 can be either linear or branched.

[0042] In formula (1) representing component A-1, R4 is either H or CH3, both of which are preferred. As a raw material for component A-1, the monomer shown in formula (7) below can be used.

[0043] [ka]

[0044] In equation (7), R1 represents (CnH2n+1) (n = an integer between 5 and 10), and R4 represents H or CH3. Preferably, n = 6 or 8.

[0045] Specifically, octyl (meth)acrylate, hexyl (meth)acrylate, and the like can be used as raw materials for component A-1.

[0046] In R2 of formula (2) representing component A-2, the number of carbon atoms m is between 1 and 10. When the number of carbon atoms m is 10 or less, it is possible to avoid the crosslinking density of the release layer of the present invention becoming sparse, to suppress the weakening of the cohesive force of the release layer itself, and further, to suppress an increase in the peeling force. The number of carbon atoms m is preferably between 2 and 8, and more preferably between 2 and 4.

[0047] In 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 shown in formula (8) below can be used.

[0048] [ka]

[0049] In equation (8), R2 represents (CmH2mOH) (m = an integer between 1 and 10) or H, and R4 represents H or CH3.

[0050] Specifically, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc., can be used as raw materials for component A-2.

[0051] (Crosslinking agent) The crosslinking agent (B) used to form the release layer of 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. Furthermore, in this invention, by using melamine as a crosslinking agent, the resin sheet can be retained from the release film without peeling off 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, it is presumed that, under heating conditions such as 180°C for 1 hour, the interaction between component A-1, where R1 is (CnH2n+1) (n=an integer between 5 and 10) in chemical formula (1), and the melamine-based crosslinking agent causes hardening shrinkage of the release layer, changing the surface morphology and increasing the water contact angle. As a result, it is presumed that the resin sheet can be retained from the release film without peeling off during pre-drying, and after drying, the resin sheet can be peeled off the release film without deformation or breakage.

[0052] 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). (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. Furthermore, because the release components of the acrylic resin (A) oriented on the surface of the release layer are fixed by the crosslinking agent, the heavy peeling force after heating is suppressed. 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 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.

[0053] 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 the 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.

[0054] 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 outer 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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). (I) 5 ≤ b / c ≤ 400 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. 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.

[0061] 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.).

[0062] The release layer of the present invention may contain additives such as adhesion enhancers and antistatic agents, as long as they do not hinder the effects of the present invention. Furthermore, to improve adhesion to the substrate, it is preferable to pre-treat the polyester film surface with an anchor coat, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc., before applying the release coating layer.

[0063] 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.

[0064] 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. Furthermore, the average surface roughness (Sa) and maximum protrusion height (P) of this 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 in the average surface roughness (Sa) and maximum protrusion height (P) of this 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.

[0065] 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 polyester film substrate, and after removing the solvent by drying, the coating 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.

[0066] 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.

[0067] 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.

[0068] The release film obtained in this invention preferably has a tape peeling force within the range shown below.

[0069] 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. 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. 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.

[0070] The release film obtained in this invention preferably has a water contact angle within the following range.

[0071] 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°. 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. 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.

[0072] 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 (2). α > β Equation (2)

[0073] 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. In the present invention, by performing the drying temperature when forming the release layer on the base film under the conditions described herein, equation (2) relating to the water contact angle can be satisfied. Furthermore, the release layer of the present invention can be used as a release film when the release layer is formed on the base film. A feature of the present invention is that, for example, when using the release film of the present invention as process paper 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, as discovered by the inventors of this application. 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 (2), can be used as an indicator. Furthermore, due to the relationship shown in formula (2) 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 object to be released can be peeled off smoothly while suppressing deformation of the object to be released. 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. Furthermore, heating does not simply increase the water contact angle; it is necessary to satisfy equation (2) relating to the water contact angle, and the present invention can have such a relationship. The heat treatment temperature for the resin sheet may be, for example, 180°C for 1 hour.

[0074] In one embodiment, the difference |(α)-(β)| between 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 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. Although the detailed mechanism has not been explored, under these conditions, hardening of 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 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. Furthermore, it becomes possible to remove the molded object without damaging it.

[0075] 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 2More than 1000N / mm 2 The following is most preferable: 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 paper such as a resin sheet. 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.

[0076] 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.

[0077] The release film obtained in this invention preferably has a pencil hardness within the following range.

[0078] The release film obtained in the present invention preferably has a pencil hardness of B or higher on its surface. When the pencil hardness is B or higher, the release film itself does not deform and maintains its flatness even when heat or pressure is applied when forming a resin sheet on the release film, which is preferable because it allows for the formation of a resin sheet of uniform thickness. The pencil hardness values ​​mentioned above are the numerical ranges obtained when measured at room temperature and correspond to the pencil hardness (H1) of the release layer surface before heating, as described later.

[0079] The release film obtained in this invention preferably has a pencil hardness of HB or higher, and more preferably F or higher, on its surface after heating at 180°C for 1 hour. When the hardness is HB or higher, the release film itself does not deform and maintains its flatness even when heat and pressure are applied when forming a resin sheet on the release film, which is preferable because it allows for the formation of a resin sheet of uniform thickness. The pencil hardness values ​​mentioned above are the numerical ranges obtained after heating at 180°C for 1 hour, and correspond to the pencil hardness (H2) of the release layer surface after heating, as described later.

[0080] In the present invention, it is preferable that the pencil hardness (H2) of the surface of the release film after heating at 180°C for 1 hour and the pencil hardness (H1) of the surface of the release film before heating satisfy the following formula (1). H2>H1 formula (1)

[0081] In this invention, the pencil hardness (H2) of the surface of the release film after heating refers to the pencil hardness of the surface of the release film measured after heating the release film at 180°C for 1 hour. In the present invention, the drying temperature when forming the release layer on the base film is carried out under the conditions described herein, thereby satisfying formula (1) relating to pencil hardness. Furthermore, the release layer of the present invention can be used as a release film when the release layer is formed on the base film. A feature of the present invention is that, for example, when using the release film of the present invention as process paper 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, as discovered by the inventors of this application. The inventors of this invention 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 pencil hardness expressed in equation (1) serves as an indicator of this change. 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. In this way, the hardening of the release film progresses further during heat treatment, increasing the pencil hardness of the release film surface. Therefore, 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, so 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. Furthermore, heating does not simply increase pencil hardness; it is necessary to satisfy equation (1) relating to pencil hardness, and the present invention can have such a relationship. The heat treatment temperature for the resin sheet may be, for example, 180°C for 1 hour.

[0082] The release film obtained in this invention, by setting the pencil hardness of the base film and the release film 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 in which the release film does not deform during the heat treatment process, and the resin sheet does not deform or tear. Thus, in addition to the release layer containing the acrylic resin (A) and crosslinking agent (B) according to the present invention, the glass transition point of the resin constituting the base film is 100°C or higher. For example, the surface hardness of the release film after heating at 180°C for 1 hour can be increased to F or higher. Furthermore, the release layer can exhibit peelability and adhesion to the object to be released. For this reason, the release film can perform its function stably even in manufacturing processes that involve multiple heating steps or manufacturing processes that heat the object to be released at high temperatures. Furthermore, the present invention can suppress twisting and delamination of the film between the substrate and the release layer, even under high temperature conditions of 180°C, due to differences in thermal shrinkage. Although it should not be interpreted as being limited to a specific theory, because the release layer contains the acrylic resin (A) and crosslinking agent (B) according to the present invention, and the glass transition point of the resin constituting the substrate film is 100°C or higher, the substrate and the release layer can maintain similar thermal shrinkage, and the release film can exhibit high dimensional stability even under high temperature conditions of 180°C. As a result, it is believed that the release layer can stably maintain its surface shape, such as surface roughness, even under heating conditions of 100°C or higher. In this invention, the resin sheet peel strength (PF1), measured under conditions where the release layer is dried at 100°C for 2 minutes, indicates the adhesion of the release film to the object to be peeled. On the other hand, the resin sheet peel strength (PF2), measured after heating the release layer at 180°C for 15 minutes, indicates the peelability to the object to be peeled. In other words, the present invention provides a release layer whose function differs after heating at 100°C and after heating at 180°C, and the release film can exhibit both adhesion to the object to be released and release properties. Thus, the present invention can provide a release layer that exhibits temperature dependence, and furthermore, the release layer of the present invention can maintain high adhesion to the substrate while controlling the adhesion to the object to be released and release properties.

[0083] 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.

[0084] 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. 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.

[0085] 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). 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.

[0086] In the present invention, a laminated film can be obtained by providing a resin layer on at least one side of the release film. The laminated film can be obtained, for example, by coating a resin product onto 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.

[0087] This 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 paper used in the manufacturing process of semiconductor-related components such as circuit boards, process paper used in the manufacturing process of electronic components such as ceramic capacitors, and protection of image display components. Similar effects can be expected.

[0088] 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]

[0089] 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.

[0090] <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.

[0091] (water contact angle) 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.

[0092] (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.

[0093] (Martens hardness of the substrate) 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: 500 mN 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

[0094] (Martens hardness of the release layer) The resin and crosslinking agent mixture used as the sample 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 coating solution was applied to the surface of a glass slide using a wire bar to prepare a glass slide sample with 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. 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

[0095] (Resin sheet peeling force under pre-drying conditions: PF1) An epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828) was used as the resin, and a phenol resin (manufactured by 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, thereby obtaining 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 thickness of 50.0 μm. 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.

[0096] (Resin sheet peeling force under post-drying process conditions: PF2) Except for changing the drying conditions to heating at a temperature of 180°C for 15 minutes, the measurement was performed in the same manner as (resin release force in the previous drying process).

[0097] (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 △.

[0098] (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 amount of 10 mg and a heating rate of 20 °C / min.

[0099] (Pencil hardness) Pencil hardness was measured and determined using the following procedure. (1) Prepare a sample by cutting the film to a size of 100mm x 75mm. (2) In accordance with JIS K 5600-5-4:1999, apply a load to the sample at a rate of 750g and 30.0mm / min. (3) Repeat steps (1) and (2) above five times, and the pencil hardness one level below the pencil hardness at which scratches occurred two or more times out of the five times will be used as the pencil hardness of the sample to be evaluated.

[0100] (Example 1) (Preparation of acrylic resin (A1) and release layer coating liquid) Hexyl acrylate (CH2=C(H)COOC6H 13 Mixing hydroxyethyl acrylate (CH2=C(H)COOC2H4OH) in a 50:50 ratio, adding toluene to achieve a solid content concentration of 40% by mass, and copolymerizing under a nitrogen atmosphere by adding 0.5 mol% azobisisobutyronitrile (AIBN) to obtain acrylic resin (A1). Acrylic resin (A1), melamine resin (Nikarac MW-30, manufactured by Nippon Carbide Co., Ltd.) as a 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. A polyethylene naphthalate film (manufactured by Toyobo Co., Ltd., Q5100, thickness: 25 μm, surface roughness (Sa): 0.006 μm, haze: 12.6%) was used as the base film.

[0101] (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.

[0102] (Example 2) (Preparation of acrylic resin (A2) and release layer coating liquid) Octyl acrylate (CH2=C(H)COOC8H) 17 Mixing hydroxyethyl acrylate (CH2=C(H)COOC2H4OH) in a ratio of 30:70, add toluene to achieve a solid content concentration of 40% by mass, and copolymerize under a nitrogen atmosphere by adding 0.5 mol% azobisisobutyronitrile (AIBN) to obtain acrylic resin (A2). 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.

[0103] (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.

[0104] (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). 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.

[0105] (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). 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.

[0106] (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). 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.

[0107] (Reference example 1) A polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., E5100, thickness: 38 μm, surface roughness (Sa): 0.0365 μm (corona-treated surface), maximum surface 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.

[0108] <Evaluation Results> Table 2 shows the evaluation results regarding the physical properties of the examples. The present invention provides a release film 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 and wrinkles, even if the release film is thin. On the other hand, in Comparative Example 1, since n=4 in R1 of component A-1 of acrylic resin (A), the tape peeling force increased significantly, and although it could not be peeled off the resin sheet under pre-drying conditions, it could not be peeled off even under post-drying conditions. In Comparative Example 2, since n=12 in R1 of 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 in R1 of component A-1 of acrylic resin (A), the tape peeling force was greatly reduced, and the resin sheet peeled off under pre-drying conditions. Furthermore, in Reference Example 6, since the base film uses PET with a pencil hardness of 2B, it was confirmed that the flatness of the film is slightly impaired compared to the present invention.

[0109] 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 by 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.

[0110] [Table 1]

[0111] [Table 2] [Industrial applicability]

[0112] 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 release layer comprises an acrylic resin (A) and a crosslinking agent (B). The acrylic resin (A) comprises component A-1 represented by the following chemical formula (Chemical Formula 1) and component A-2 represented by (Chemical Formula 2). The aforementioned release layer substantially does not contain any silicone components, and the release layer is laminated on a base film, The glass transition temperature of the resin constituting the base film is 100°C or higher. The pencil hardness of the base film is B or higher. The pencil hardness (H2) of the release film after heating at 180°C for 1 hour is HB or higher. A release film whose pencil hardness (H2) after heating at 180°C for 1 hour and the pencil hardness (H1) of the release film before heating satisfy the following formula (1). H2 > H1 Formula (1) 【Chemistry 1】 In chemical formula (1), R １ is (CnH2n+1) (n = an integer between 5 and 10), R ４ is H or CH ３ This indicates. 【Chemistry 2】 In chemical formula (2), R ２ (CmH2mOH) (m = an integer between 1 and 10) or H, R ４ is H or CH ３ This indicates.

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

3. The Martens hardness of the base film used in the aforementioned release film is 170 N / mm². ２ The release film according to claim 1 or 2.

4. The release film according to claim 1, 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 (2). α > β Equation (2)

5. The aforementioned base film is a film cured from a composition containing polyester resin, The release film according to claim 1, wherein the polyester resin contains naphthalenedicarboxylic acid as a dicarboxylic acid component.

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