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

Release film

[0001] The present invention relates to a release film that can be used for molding resin sheets, etc. In particular, the present invention relates to a release film for molding resin sheets used for electronic components.

[0002] Conventionally, release films based on polyester film have high heat resistance and mechanical properties and have been used as process films used in solution casting 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, which has led to a demand for thinner resin sheets used in electronic components. When resin sheets are made thinner, even a small force may be applied when peeling them from the process film. For this reason, release films used as process films have been required to have a small peel force so that they can be peeled without damaging the resin sheet. For this reason, a technology such as that described in Patent Document 1 has been disclosed, proposing a release sheet whose release force on the release layer surface changes little even over a long period of time since the release sheet was manufactured.

[0003] JP 2023-106150 A

[0004] However, in the technology of Patent Document 1, while a small peeling force is required so that resin sheets and the like can be peeled off without damaging them when used in electronic components, if the peeling force is too small, the resin may peel off at an unintended time, for example, during pre-drying of the resin, which could result in a decrease in yield.

[0005] To improve these problems, release films with high peeling strength have been proposed. However, although the resin sheet does not peel off from the process film in the pre-drying process, the resin sheet also does not peel off from the process film after the main drying process, which results in the problem that the original purpose cannot be achieved.

[0006] In addition to thinner resin sheets, thinner release films are also being sought from the viewpoint of improving productivity. However, if the release film is thin, it may deform or wrinkle due to heat when heat or pressure is applied, and the peel force when the resin sheet is peeled from the release film may not be able to be maintained constant, resulting in deformation or tearing of the resin sheet.

[0007] As described above, there is a problem in that existing release films are unable to fully demonstrate their performance, and improvements are required.

[0008] The present invention solves the above-mentioned problems, and aims to provide a release film in which the resin sheet does not peel off from the release film during pre-drying, the resin sheet can be peeled off from the release film after main drying without deformation or tearing, and even if the release film is thin, the release film does not deform during the thermal process, and the resin sheet does not deform or tear.

[0009] As a result of extensive research to solve the above problems, the present inventors have found that the above object can be achieved by a release film having the following configuration, and have 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, wherein the release layer contains an acrylic resin A and a crosslinking agent B, the acrylic resin A contains, as structural units, an A-1 component represented by the following general formula (1) and an A-2 component represented by the following general formula (2), the release layer is substantially free of a silicone component, and the glass transition point of the resin constituting the base film is 100°C or higher.

[0011]

[0012] (In general formula (1), R １ (C ｎ H ２ｎ＋１ ) (n = an integer of 5 or more and 10 or less), R ３ is H or CH ３ Indicates.)

[0013] (In general formula (2), R ２ (Cｍ H ２ｍ OH) (m = integer of 1 or more and 10 or less) or H, R ４ is H or CH ３ [2] The release film according to [1], wherein the molar ratio of the A-1 component to the total number of moles of the A-1 component and the A-2 component is 30 mol % or more and 90 mol % or less.

[0014] [3] The release film according to [1] or [2], wherein the tape peel strength of the release layer is 5000 mN / 50 mm or more and 15000 mN / 50 mm or less at a peeling speed of 300 mm / min. [4] The Martens hardness of the base film is 150 N / mm ２ [5] The release film according to any one 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 formula (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.

[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 after main drying, the resin sheet can be peeled off from the release film without deformation or tearing. 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. Furthermore, for example, the peel force when the resin sheet is peeled off from the release film can be kept constant, and deformation and tearing of the resin sheet can be prevented. Therefore, the resin sheet produced using the release film of the present invention can also be applied to electronic components, etc.

[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 is substantially free of silicone components. The acrylic resin A contains, as structural units, an A-1 component represented by the following general formula (1) and an A-2 component represented by the following general formula (2).

[0018]

[0019] (In general formula (1), R １ (C ｎ H ２ｎ＋１ ) (n = an integer of 5 or more and 10 or less), R ３ is H or CH ３ Indicates.)

[0020] (In general formula (2), R ２ (C ｍ H ２ｍ OH) (m = integer of 1 or more and 10 or less) or H, R ４ is H or CH ３ The glass transition point of the resin constituting the base film is 100° C. or higher.

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

[0022] In particular, in the present invention, deformation that can occur when heat and pressure are applied to the release film can be suppressed, and wrinkles can also be suppressed. Furthermore, by exhibiting such effects, the release film of the present invention can maintain a constant peel force when the resin sheet, which is the object to be released, is peeled from the release film, and deformation and tearing of the resin sheet can be suppressed.

[0023] Furthermore, by laminating the base film and the release layer in this order in the present invention, it is possible to maintain a good balance between the dimensional stability and surface smoothness of the base film when heated and the thermal shrinkage and expansion that the release layer may have when heated.

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

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

[0026] Furthermore, the resin sheet does not peel off from the release film during pre-drying, and after main drying, the resin sheet can be peeled off from the release film without deformation or tearing. Furthermore, even if the release film is thin, the release film does not deform during the heat treatment process, and a release film can be obtained that does not cause deformation or tearing in the resin sheet.

[0027] As the substrate film, any known film having a glass transition point of 100° C. or higher can be used. For example, a resin film formed from a polyester such as polyethylene naphthalate, polycarbonate, polyamideimide, polyimide, or the like can be used as the substrate film. In particular, from the viewpoint of cost and productivity, a polyester film is preferred, and a polyethylene naphthalate film or a copolymer thereof is more preferred.

[0028] In one embodiment, the substrate film contains a polyester resin having a structural unit derived from naphthalenedicarboxylic acid as a dicarboxylic acid component. While not limited to a specific theory, the substrate film containing naphthalenedicarboxylic acid as a dicarboxylic acid component can exhibit 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 peel force. Since the substrate film can maintain high surface smoothness after heating, the heat treatment temperature can be appropriately selected depending on the resin sheet to be manufactured.

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

[0030] The thickness of the base film is preferably 10 μm or more and 188 μm or less, and more preferably 16 μm or more and 100 μm or less. A base film thickness of 10 μm or more can suppress deformation due to heat during production, processing, and molding of the base film. On the other hand, a base film thickness of 188 μm or less can suppress the amount of base film discarded after use while satisfying the physical properties required of the base film, thereby reducing the burden on the environment. Furthermore, a base film thickness of 100 μm or less is preferable because a longer roll of product can be produced in a single production run, improving productivity in terms of base film loss and transportability.

[0031] An easy-adhesion coating may be disposed between the base film and the release layer to improve adhesion, and a coating may be disposed on the surface of the base film opposite to the surface on which the release layer is disposed to impart easy slippage, heat resistance, antistatic properties, etc.

[0032] The average surface roughness (Sa) of the region on which the release layer of the substrate film used in the present invention is laminated is preferably in the range of 1 to 50 nm, more preferably 2 to 30 nm. The maximum protrusion height (P) of the surface on which the release layer of the substrate film used in the present invention is laminated is preferably 2 μm or less, more preferably 1.5 μm or less. When Sa is 50 nm or less and P is 2 μm or less, it is possible to suppress unevenness in the thickness of the release layer and maintain constant smoothness of the release layer surface. Furthermore, it is possible to reduce unevenness in the thickness of the release target object, and to suppress the possibility of tearing starting from a thin portion when the release target object is peeled from the release film.

[0033] The average surface roughness (Sa) of the region opposite the surface on which the release layer of the substrate film used in the present invention is preferably in the range of 3 to 100 nm, more preferably 5 to 30 nm. The maximum protrusion height (P) of the region opposite the surface on which the release layer of the substrate film used in the present invention is preferably 2 μm or less, 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 properties. Furthermore, if P is 2 μm or less, the release layer surface is not damaged during winding, reducing the possibility of partial peeling of the release layer. Furthermore, the possibility of tearing originating from the peeled portion of the release layer can be suppressed when the release target is peeled from the release film.

[0034] The haze of the substrate film used in the present invention is preferably 0.1% or more and 20% or less, for example, 3% or more and 17% or less, and may be 6% or more and 15% or less. At present, the mechanism has not been analyzed, but it is presumed that by having the above haze value, when the release film is dried at high temperatures, the substrate film can maintain a moderate surface unevenness, which also contributes to the cooling properties of the release film, and the release film tends to exhibit desirable heat resistance. In addition, there is a tendency for the interaction with the release layer in the present invention to be more pronounced.

[0035] The base film of the present invention can be made from recycled raw materials such as polyester film scraps and PET bottles. Since the present invention can use recycled raw materials such as film scraps and PET bottles, the environmental impact can be significantly reduced. Furthermore, even in embodiments that include recycled raw materials such as film scraps and PET bottles, the film's slipperiness and ease of air escape can be maintained. The release layer of the present invention can be made from polyester films that have been used in various applications, which can be appropriately collected, processed, and reused.

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

[0037] For example, the size of the fine particles in the base film of the present invention may be in the range of 0.001 μm to 10 μm, and the 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 of the base film on which the release layer is laminated.

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

[0039] The glass transition point of the resin constituting the substrate 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 the glass transition point is 100°C or higher, even when heat or pressure is applied when molding a resin sheet on the release film, the release film itself does not deform and the flatness is maintained, so a resin sheet of uniform thickness can be formed, which is preferable. When the glass transition point is 115°C or higher, it is particularly preferable because a resin sheet of even uniform thickness can be formed without impairing the flatness of the film. The glass transition point is, for example, 150°C or lower, or may be 140°C or lower, or may be 130°C or lower. In one embodiment, the glass transition point of the resin constituting the substrate 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] By virtue of these characteristics, the present invention allows the resin sheet or the like to be peeled off from the release layer with a constant peeling force even when subjected to heat treatment at 180° C. for 1 hour.

[0041] In addition, in the case of a film having a glass transition point of less than 100°C, for example, a PET film having a glass transition point of less than 100°C, the surface smoothness of the substrate film tends to be impaired after heat treatment at 180°C for 1 hour, and there is a risk that the resin sheet will peel off from the release film during pre-drying, and that after main drying, there is a risk that the resin sheet will deform or break due to deformation of the substrate film.

[0042] Another specific market demand is the reduction in the cost of release film processing. One way to reduce the cost of release layer processing is, for example, to increase the film conveying speed to process it at high speed. However, in the present invention, increasing the conveying speed can lead to deterioration in the winding shape, such as winding slippage, so the tension during conveying must also be increased, which can make the film more susceptible to wrinkling during conveying. Furthermore, since the film's residence time in the furnace is shortened, the amount of heat applied to the film decreases, resulting in issues such as insufficient curing of the release layer due to insufficient drying and blocking of the film roll due to insufficient curing.

[0043] In the present invention, since the glass transition point of the resin constituting the base film is 100°C or higher, it is possible to increase the temperature of the drying oven. For example, the present invention can avoid the problem that can arise with conventional combinations of base film and release layer, in which the amount of drying heat increases and the film becomes more likely to wrinkle during transportation. Furthermore, since the glass transition point 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, so the release film can be processed at high speed, which can contribute to cost reduction.

[0044] The water vapor permeability of the substrate film used in the present invention is 1.0 g / m ２ ・d or more 25.0g / m ２ d, and 3.0 g / m ２ ・d or more 15.0g / m ２ d, more preferably 5.0 g / m ２ ・d or more 10.0g / m ２ It is most preferable that the thickness is d or less.

[0045] By setting the water vapor permeability within the above range, when a release layer is formed on a substrate film, a release film having a desired peel strength without unevenness or stickiness can be formed. ２ By having a water vapor permeability of d or more, as will be described later, when a coating solution containing a solvent is applied to form a release layer on the substrate film, the drying of the solvent proceeds efficiently, and unevenness and stickiness on the surface of the release film due to insufficient drying are suppressed, which is preferable. On the other hand, although the detailed mechanism is not clear, ２ It is believed that by keeping the drying time at or below d, the solvent does not volatilize suddenly during drying, but rather volatilizes over a certain period of time, which allows the release components in the coating liquid to be efficiently oriented on the surface of the release layer, thereby forming a release film having the desired peel strength. The water vapor permeability in the present invention can be evaluated, for example, by the water vapor permeability measured when the substrate film is 25 μm thick.

[0046] The Martens hardness (HMT115) of the substrate film used in the present invention is 150 N / mm ２More than 400N / mm ２ Preferably, it is 170 N / mm or less. ２ More than 370N / mm ２ More preferably, it is 200 N / mm or less. ２ 350N / mm or more ２ By setting the Martens hardness of the base film within the above range, when a release film is produced by providing a release layer on the base film and used as a processing film for a resin sheet or the like, it is possible to provide a release film that can prevent deformation of the object to be released when the object to be released is peeled off.

[0047] Martens hardness (HMT115) of the base film is 150 N / mm ２ By satisfying the above, the elastic modulus of the release film becomes large, and when the object to be released is peeled off from the release film, the release film does not deform following the object to be released, so that excessive stress is not applied to a part of the object to be released, and the object can be peeled off with a uniform force, and deformation of the object to be released can be prevented. On the other hand, when the Martens hardness (HMT115) of the base film is 400 N / mm ２ It is preferable that the thickness is not more than 100 μm, since this results in good handleability and ease of handling.

[0048] (Release Layer) The release layer in the present invention is a release layer that contains an acrylic resin A and a crosslinking agent B, and does not substantially contain a silicone component. For example, a release layer can be formed by curing a release layer-forming composition that contains an acrylic resin A and a crosslinking agent B. In the present invention, the acrylic resin A contains, as structural units, an A-1 component represented by the following general formula (1) and an A-2 component represented by the following general formula (2), and in particular, in general formula (1), R １ (C ｎ H ２ｎ＋１ ) (n=an integer of 5 or more and 10 or less), the effects of the present invention can be achieved.

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

[0050]

[0051] In general formula (1), R １ (C ｎ H ２ｎ＋１ ) (n = an integer of 5 or more and 10 or less), R ３ is H or CH ３ Preferably, n is an integer of 5 or more and 9 or less, for example, n is an integer of 6 or more and 9 or less, or n is an integer of 6 or more and 8 or less.

[0052]

[0053] In general formula (2), R ２ (C ｍ H ２ｍ OH) (m = integer of 1 or more and 10 or less) or H, R ４ is H or CH ３ In the above formula, for example, m is an integer of 1 or more and 8 or less, m is an integer of 1 or more and 6 or less, or m is an integer of 1 or more and 4 or less.

[0054] When the total mass of the A-1 component and the A-2 component of the acrylic resin A in the release layer is taken as 100 parts by mass, the mass of A-1 is preferably 30 parts by mass or more, more preferably 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 preferred because it tends to reduce the releasability of the 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. When the amount of A-1 component is within the above range, the various physical properties of the release layer can be maintained before and after heating.

[0056] For the same reason, the molar ratio of the A-1 component to the total number of moles of the A-1 component and the A-2 component 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 the copolymerization component introduced into the acrylic resin A can be determined by nuclear magnetic resonance spectroscopy ( 1 H-NMR, 13 C-NMR: Varian Unity 400, manufactured by Agilent) can be used to confirm this.

[0057] In the present invention, the mechanism has not been analyzed, but in general formula (1), R １ (C ｎ H ２ｎ＋１ ) (n = an integer of 5 or more and 10 or less) is more than 30 parts by mass, there is a tendency that a release film that does not peel off in the pre-drying step and has light releasability in the post-drying step can be provided.

[0058] In particular, the more the amount of component A-1, where n in general formula (1) is an integer of 6 or more and 8 or less, exceeds 30 parts by mass, the better the above effects can be exhibited.

[0059] In the general formula (1) representing the component A-1, R １ is an alkyl group having a carbon number n of 5 or more and 10 or less. When the carbon number n is 5 or more, the A-1 component can exhibit good releasability after the drying step. In addition, it is possible to suppress the release layer from exhibiting adhesiveness, which can be caused by an alkyl group having a small number of carbon atoms. On the other hand, when the carbon number n is 10 or less, it is possible to ensure sufficient wettability of the coating surface of the release layer, and also possible to ensure appropriate adhesion in the pre-drying step. The carbon number n is preferably 6 or more and 9 or less, and more preferably 6 or more and 8 or less. In addition, R １ may be either linear or branched.

[0060] In the general formula (1) representing the component A-1, R ３ is H or CH ３ As a raw material for the component A-1, a monomer represented by the following general formula (7) can be used.

[0061]

[0062] In general formula (7), R １ (C ｎ H ２ｎ＋１ ) (n = an integer of 5 or more and 10 or less), R ３ is H or CH ３ Preferably, n is 6 or more and 8 or less.

[0063] Specific examples of the raw material for component A-1 include octyl (meth)acrylate and hexyl (meth)acrylate.

[0064] R of general formula (2) representing component A-2 ２ In particular, the carbon number m is 1 or more and 10 or less. When the carbon number m is 10 or less, the crosslink density of the release layer in the present invention can be prevented from becoming sparse, the cohesive force of the release layer itself can be prevented from weakening, and further, the peel force can be prevented from becoming heavy. The carbon number 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 the A-2 component, R ４ is H or CH ３ As a raw material for component A-2, a monomer represented by the following general formula (8) can be used.

[0066]

[0067] In general formula (8), R ２ (C ｍ H ２ｍ OH) (m = integer of 1 or more and 10 or less) or H, R ４ is H or CH ３ Shows.

[0068] Specific examples of the raw material for component A-2 include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

[0069] Since the acrylic resin A contained in the release layer of the present invention has a long-chain alkyl group, the releasability 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 with respect to, for example, a resin composition that forms a resin sheet. Furthermore, the acrylic resin A according to the present invention can provide a release film that does not peel off from a release target, such as a resin sheet, formed on the release layer in the pre-drying step, but has light releasability after the main drying step.

[0070] The acrylic resin A may further contain, as a structural unit, a copolymerization component other than those represented by general formulas (1) and (2). The content of the other copolymerization component in the acrylic resin A is preferably 10 mol % or less, more preferably 3 mol % or less, and most preferably 0 mol %.

[0071] Examples of other copolymerization components include alkyl methacrylates such as methyl methacrylate (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, or a graft copolymer.

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

[0074] In the present invention, the pre-drying step refers to the state after heating at a temperature of 100°C for 2 minutes, and the main drying step refers to the state after heating at a temperature of 180°C for 15 minutes. In addition, in the present invention, "after heating" does not only mean immediately after heating, but also means a state after cooling to an ambient temperature or lower (for example, 40°C or lower). Furthermore, the main drying may be performed in multiple stages.

[0075] Furthermore, the release layer according to the present invention contains acrylic resin A and is substantially free of silicone components. This prevents the silicone components from being transferred to the release target, thereby preventing, for example, the release target from being contaminated by silicone, thereby avoiding malfunctions of electronic devices caused by the release target. In this specification, "substantially free of silicone components" means that silicone components are not intentionally added to the components forming the release layer. For example, there is a possibility that a very small amount of silicone components may be present unintentionally during the manufacturing process of the release layer. Taking this into consideration, the amount of silicone components contained in the release layer is preferably less than 0.1 parts by mass per 100 parts by mass of the release layer.

[0076] (Crosslinking Agent) As the crosslinking agent B used in forming the release layer in the present invention, polyisocyanate, melamine, epoxy, aluminum chelate, titanium chelate, ultraviolet curable resin, or a mixture of two or more of these can be used. Among them, the use of melamine is preferred because the cured film is rigid and has excellent chemical resistance and weather resistance. When crosslinking with aluminum chelate or titanium chelate, the inclusion of metal components may be undesirable depending on the application.

[0077] In addition, in the present invention, by using melamine as a crosslinking agent, the resin sheet can be held without peeling off from the release film during pre-drying, and after drying, the resin sheet can be peeled off from the release film without deformation or breakage. １ (C ｎ H ２ｎ＋１It is presumed that when the A-1 component represented by the formula (n = an integer of 5 to 10) and the melamine-based crosslinking agent are heated, for example, at 180°C for 1 hour, the interaction between the two components causes the release layer to cure and shrink, changing the surface morphology and increasing the water contact angle. As a result, it is presumed that the resin sheet can be held without peeling from the release film during pre-drying, and that after drying, the resin sheet can be peeled from the release film without deformation or breakage.

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

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

[0080] Furthermore, since the release component of the acrylic resin A 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 clear, it is believed that by setting the ratio a / b of the mass (a) of the acrylic resin to the mass (b) of the crosslinking agent within the above range, the acrylic resin segregated in the outermost layer of the release layer is efficiently and sufficiently crosslinked, and that, for example, even when the release film is heated, the releasability of the release film does not change significantly.

[0082] If the ratio a / b of the mass (a) of the acrylic resin to the mass (b) of the crosslinking agent is 0.001 or less, the amount of the release component of the acrylic resin A present on the surface of the release layer will be reduced. Therefore, for example, in an embodiment in which a resin sheet is used as the object to be released, the peeling force will be strong, which may lead to deformation or tearing of the resin sheet.

[0083] Furthermore, although theoretical analysis has not been performed, if the ratio a / b of the mass (a) of the acrylic resin to the mass (b) of the crosslinking agent is 0.2 or more, the acrylic resin segregated in the outermost layer of the release layer is not crosslinked efficiently and sufficiently, and for example, when heated, the original release properties may not be exhibited.

[0084] The melamine-based compound used in the release layer of the present invention can be any common compound, but is not particularly limited thereto. It is preferably obtained by condensing melamine with formaldehyde and having one or more triazine rings and one or more methylol groups and / or alkoxymethyl groups per molecule. Specifically, a compound obtained by subjecting a methylol melamine derivative obtained by condensing melamine with formaldehyde to a dehydration condensation reaction with a lower alcohol such as methyl alcohol, ethyl alcohol, isopropyl alcohol, or butyl alcohol to etherification is preferred. Examples of methylol melamine derivatives include monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, and hexamethylol melamine. One or more compounds may be used.

[0085] The melamine used in the present invention may 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 Allnex Japan Co., Ltd.), Nikalac MW-30M, Nikalac MW-30, Nikalac MW-30HM, Nikalac MW-390, Examples of such resins include Nikalac MW-100LM, Nikalac MA-1-750LM, Nikalac MW-22, Nikalac MS-21, Nikalac MS-11, Nikalac MW-24A-1, Nikalac MS-001, Nikalac MA-1-002, Nikalac MA-1-730, Nikalac MA-1-750, Nikalac MA-1-708, Nikalac MA-1-706, Nikalac MA-1-042, Nikalac MA-1-035, Nikalac MA-1-45, Nikalac MA-1-43, Nikalac MA-1-417, and Nikalac MA-1-410 (manufactured by Nippon Carbide Corporation). Among these, full-ether type methylated melamine resins are preferred in terms of low-temperature, short-time curing properties and adhesion to polyester films. Commercially available products include Cymel 303LF and Nikalac MW-30.

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

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

[0088] Sulfonic acid catalysts have higher acidity and better reactivity than other acid catalysts such as carboxylic acid catalysts, and therefore can process the release layer at lower temperatures, which is preferable because it can prevent the film from losing flatness and the rolled appearance from being deteriorated due to heat during processing.

[0089] In the present invention, the ratio b / c of ​​the mass (b) of the crosslinking agent to the mass (c) of the acid catalyst contained in the release layer 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 or more and 400 or less, for example, 10 or more and 200 or less, or may be 20 or more and 100 or less. By setting the ratio b / c of ​​the mass of the crosslinking agent (b) to the acid catalyst (c) within the above range, the peel force of the release film can be controlled within the desired range.

[0091] It is preferable that the ratio b / c of ​​the mass (b) of the crosslinking agent to the acid catalyst (c) is 400 or less, because the crosslinking reaction of the melamine compound is promoted, the curing of the release film progresses, and stickiness and blocking of the film roll are suppressed. Also, it is preferable that the ratio b / c of ​​the mass (b) of the crosslinking agent to the acid catalyst (c) is 5 or more, because the release film after curing has appropriate adhesion, and when a resin sheet is provided on the release film, peeling of the resin sheet at unintended times such as during pre-drying or the conveying process can be prevented.

[0092] The sulfonic acid catalyst used in the present invention may be commercially available. Examples of commercially available products include Dryer (registered trademark) 900 (p-toluenesulfonic acid, manufactured by Hitachi Chemical Co., Ltd.), NACURE (registered trademark) DNNDSA series (dinonylnaphthalene disulfonic acid, manufactured by Kusumoto Chemicals Co., Ltd.), NACURE (registered trademark) DNNDSA series (dinonylnaphthalene (mono)sulfonic acid, manufactured by Kusumoto Chemicals Co., Ltd.), NACURE (registered trademark) DDBSA series (dodecylbenzenesulfonic acid, manufactured by Kusumoto Chemicals Co., Ltd.), and NACURE (registered trademark) p-TSA series (p-toluenesulfonic acid, manufactured by Kusumoto Chemicals Co., Ltd.).

[0093] The release layer in the present invention may contain additives such as an adhesion improver and an antistatic agent, as long as the effects of the present invention are not impaired. In order to improve adhesion to the substrate film, it is also preferable to subject the surface of the polyester film to pretreatment such as anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment before providing the release coating layer.

[0094] The thickness of the release layer is preferably 0.01 μm or more and 10 μm or less, 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 peeling force may become unstable. On the other hand, if the thickness of the release layer exceeds 10 μm, the proportion of recycled raw materials used decreases, which is uneconomical and undesirable.

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

[0096] Furthermore, the rate of change in the regional surface average roughness (Sa) and the maximum protrusion height (P) before and after heating is preferably within 20%, more preferably within 10%, and even more preferably within 5%. If the rate of change in the regional surface average roughness (Sa) and the maximum protrusion height (P) before and after heating is within 20%, the adhesion area between the release layer and the object to be released increases after heating, and the anchor effect reduces the possibility of heavy peeling when the object to be released is peeled from the release layer, which is preferable.

[0097] In the present invention, the method for forming the release coating layer is not particularly limited, and a method is used in which a coating liquid in which a release resin is dissolved or dispersed is spread on one side of a substrate film by coating or the like, the solvent is removed by drying, and then the resulting coating is heated, heat-cured, or ultraviolet-cured. In this case, the drying temperature during solvent drying and heat-curing is preferably 180°C or less, more preferably 160°C or less, and most preferably 140°C or less. 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 less, the flatness of the film is maintained and there is little risk of uneven thickness of the release layer, which is preferable. When the temperature is 140°C or less, the film can be processed without impairing the flatness of the film, and there is a further reduction in the risk of uneven thickness of the release layer, which is particularly preferable.

[0098] In the present invention, the coating liquid used to apply the release coating layer is not particularly limited, but it is preferable to add a solvent having a boiling point of 70° C. or higher. Adding a solvent having a boiling point of 70° C. or higher can prevent bumping during drying, level the coating film, and improve 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] As a method for applying the coating liquid, any known coating method can be applied, and conventionally known methods such as roll coating methods such as 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 the present invention preferably has a tape peeling force in the range shown below.

[0101] The release film obtained by the present invention may have a tape peel strength at a peel speed of 300 mm / min of 5,000 mN / 50 mm or more and 15,000 mN / 50 mm or less, for example, 6,000 mN / 50 mm or more and 13,000 mN / 50 mm or less, 7,500 mN / 50 mm or more and 12,000 mN / 50 mm or less, or 8,000 mN / 50 mm or more and 12,000 mN / 50 mm or less. Although not intended to be limited by a particular theory, in the present invention, a tape peel strength within the above range can be achieved by setting the ratio a / b of the mass (a) of the acrylic resin to the mass (b) of the crosslinking agent within the range of 0.001 or more and 0.2 or less.

[0102] A tape peeling strength within the above range is preferable, for example, because the resin sheet can be peeled off without deformation or tearing when formed. A tape peeling strength of 5000 mN / 50 mm or more is preferable, because the possibility of peeling off at an unintended timing, such as during a pre-drying process of the resin sheet, is low. Furthermore, a tape peeling strength of 15000 mN / 50 mm or less is preferable, because the possibility of the release object being deformed when peeled off is low.

[0103] The tape peeling force means the tape peeling force at a peeling speed of 300 mm / min., and can be used to evaluate the peeling force when peeling off an object to be released, such as a pressure-sensitive adhesive (e.g., acrylic pressure-sensitive adhesive tape (No. 31B, manufactured by Nitto Denko Corporation)) placed on the release layer according to the present invention. The tape peeling force can be measured at room temperature (25°C).

[0104] The release film obtained in the present invention preferably has a water contact angle in the range shown below.

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

[0106] A water contact angle within the above range is preferable because, for example, when a resin sheet is formed, it can be peeled off without deformation or tearing. A water contact angle of 80° or less is preferable because there is little possibility of peeling off at an unintended timing, for example, during a pre-drying process of the resin sheet. Furthermore, a water contact angle of 50° or more is preferable because there is little possibility of the release object being deformed when it is peeled off.

[0107] The 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, which will be described later.

[0108] It is preferable that 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).

[0109] α>β (1)

[0110] In the present invention, the water contact angle (α) of the surface of the release layer after heating means 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 a release layer on a substrate film under the conditions described in this specification, it is possible to satisfy the formula (1) regarding the water contact angle. Furthermore, the release layer in the present invention can be used as a release film in a state in which the release layer is formed on a substrate film, but the present inventors have found that, as a feature of the present invention, for example, when the release film in the present invention is used as a process film, in the process of performing heat treatment when forming a resin sheet, the curing of the release film can be promoted and the surface morphology of the release layer can be controlled.

[0112] The present inventors have found that the releasability of the release layer can be changed after production of the release film and during the resin sheet formation process, and have found the relationship of formula (1) relating to the water contact angle as an index for this.

[0113] Furthermore, by satisfying the relationship of the above formula (1), at room temperature, the resin sheet-forming composition or the film-like resin sheet precursor can be adhered to the release layer on the release film, and the adhesion of the resin sheet during production can be maintained when heated, and the object to be released can be successfully peeled off while suppressing deformation of the object to be released.

[0114] In this way, hardening in the release film progresses further during the heat treatment, causing the release layer to shrink during hardening and changing the surface morphology, which increases the water contact angle. As a result, a small gap is formed between the release film and the resin sheet, reducing the possibility of deformation of the object to be released when it is peeled off.

[0115] Furthermore, heating does not simply increase the water contact angle, but rather the formula (1) regarding the water contact angle must be satisfied, 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 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 more, for example, 1.35 or more. 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, by satisfying these conditions, curing in the release film further progresses during the heat treatment, causing cure shrinkage of the release layer, and changing the surface morphology, thereby increasing the water contact angle. As a result, a small gap is formed between the release film and the resin sheet, reducing the possibility of deformation of the release object when peeled off. It is also assumed that the surface morphology does not change significantly on the nanoscale. The effects of the present invention can be particularly demonstrated 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. Furthermore, peeling is possible without damaging the release object.

[0118] The release film obtained in the present invention has a release layer with a Martens hardness (HMT115) of 200 N / mm ２ More than 1500N / mm ２ Preferably, it is 300 N / mm or less. ２ More than 1250N / mm ２ More preferably, it is 350 N / mm or less. ２ More than 1000N / mm２ Most preferably, the following:

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

[0120] Martens hardness (HMT115) of the release layer is 200 N / mm ２ As a result of the above, when the object to be released is peeled off from the release film, the release layer does not deform to follow the object to be released, so excessive stress is not applied to any part of the object to be released, and the object can be peeled off with a uniform force, preventing deformation of the object to be released.

[0121] In the release film obtained by the present invention, by combining the base film and the release layer so that the Martens hardness of each falls within the above-mentioned range, the resin sheet does not peel off from the release film during pre-drying, and the resin sheet can be peeled off from the release film without deformation or breakage after main drying. 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 step, and the resin sheet does not deform or break.

[0122] It is preferable that the release film obtained in the present invention is such that the resin sheet does not peel off from the release film when the resin sheet peel force is measured under the pre-drying process conditions. If the resin sheet does not peel off from the release film, for example, when the resin sheet is formed, there is a low possibility that the resin sheet will peel off at an unintended timing such as the pre-drying process, which is preferable.

[0123] When the release film obtained in the present invention is subjected to a resin sheet peel force measurement under the post-drying process conditions, the peel force is preferably 1000 mN / 50 mm or less, more preferably 500 mN / 50 mm or less, and most preferably 300 mN / 50 mm or less. Alternatively, the peel force may be 5 mN / 50 mm or more, or 10 mN / 50 mm or more.

[0124] If the thickness is within the above range, the release object is less likely to be deformed when it is peeled off after heating in the post-drying step or the like, which is preferable.

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

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

[0127] In the present invention, a laminate film can be obtained by providing a resin layer on at least one side of a release film. The laminate 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, a resin layer can be provided on the side of the release layer opposite the substrate film.

[0128] The present invention can also be applied to other uses, such as battery components, pressure-sensitive adhesive layer protection (protection for OCA (Optical Clear Adhesive), protection for pressure-sensitive adhesive tape, etc.), separators for transdermal drug patches in the medical field, process films used in the manufacturing process of semiconductor-related parts such as circuit boards, process films used in the manufacturing process of electronic parts such as ceramic capacitors, and protection of image display members, and similar effects are expected.

[0129] In one embodiment, the release film of the present invention, due to the properties of the components contained in the release layer, can better exhibit the effects of the present invention in a release film for producing electronic components such as ceramic capacitors, a release film for molding a resin sheet containing an epoxy resin, a release film for forming an all-solid-state battery, and a release film for molding a resin sheet having a urethane structure.

[0130] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The property values ​​used in the present invention were evaluated using the following methods.

[0131] <Evaluation> (Tape Peeling Strength) An adhesive tape ("31B" manufactured by Nitto Denko Corporation) was attached to the surface of a release film, and after pressing with a pressure roller at a linear pressure of 5 kgf / mm, the tape was left for 20 hours under conditions of a temperature of 22°C and a humidity of 60%. The release film to which the adhesive tape was attached was cut into a strip of 25 mm wide and 150 mm long. One end of the adhesive tape was fixed, one end of the release film was supported, and the release film side was pulled at a speed of 300 mm / min to measure the T-peel strength. A tensile tester ("AUTOGRAPHAG-A-1" manufactured by Shimadzu Corporation) was used for the measurement.

[0132] (Water Contact Angle Before Heating) The contact angle of water in contact with the surface of the release layer was measured under conditions of 22° C. and 60% RH using a contact angle meter ("Fully Automatic Contact Angle Meter DM-701" manufactured by Kyowa Interface Science Co., Ltd.).

[0133] (Water contact angle after heating) Using a contact angle meter ("Fully automatic contact angle meter DM-701" manufactured by Kyowa Interface Science Co., Ltd.), the release film was placed in an oven set at 180°C, and after 1 hour, it was removed from the oven and left to cool to room temperature. The contact angle of water in contact with the surface of the release layer was measured under conditions of 22°C and 60% RH.

[0134] (Martens Hardness of Substrate Film) The substrate film was cut into a size of 0.5 mm x 0.5 mm, fixed on a glass plate using adhesive tape, and subjected to a load-unload test using a dynamic ultra-microhardness tester (DUH-211S, manufactured by Shimadzu Corporation). From this measurement, the Martens hardness (HMT115) was calculated using the following formula (average value of n = 10): HMT115 = F / (26.43 × h ２ ) (N / mm ２ ) (F: load (N), h: indentation depth (mm)) (Measurement conditions) Indenter used: diamond regular triangular pyramidal indenter (edge ​​angle: 115°) Measurement mode: load-unload test Test force: 500 mN Minimum test force: 1.96 mN Load rate: 7.0 mN / sec Load holding time: 5 sec Unload holding time: 5 sec Measurement atmosphere: 25±1°C, 65±5% RH Measurement number: 10

[0135] (Martens hardness of release layer) A sample resin and crosslinking agent mixed composition was prepared in a mixed solvent (25°C) of 50% by mass of toluene and 50% by mass of MEK so that the solid content concentration was 20% by mass. The coating liquid 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 left to stand in a hot air circulating oven set at a temperature of 130°C for 5 minutes, and then removed for heat treatment.

[0136] A load-unload test was performed on the surface of the obtained sample using a dynamic ultra-microhardness tester (DUH-211S, manufactured by Shimadzu Corporation). From this measurement, the Martens hardness (HMT115) was calculated using the following formula (average value of n=10): HMT115=F / (26.43×h ２ ) (N / mm ２ ) (F: load (N), h: indentation depth (mm)) (Measurement conditions) Indenter used: diamond regular triangular pyramidal indenter (edge ​​angle: 115°) Measurement mode: indentation depth setting load-unload test Minimum test force: 0.002 mN Load speed: 0.0150 mN / sec Load holding time: 3 sec Unload holding time: 3 sec Indentation depth: 0.1 μm Measurement atmosphere: 25±1°C, 65±5% RH Measurement number: 10

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

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

[0139] (Resin sheet peeling force under post-drying process conditions: PF2) Measurement was carried out in the same manner as (Resin peeling force in pre-drying process), except that the drying conditions were changed to heating at a temperature of 180° C. for 15 minutes.

[0140] (Film Flatness) A film sample 1 m wide x 10 m long cut from the center of the width direction of the release film was placed under a three-wavelength fluorescent lamp so that the width direction of the film sample was parallel to the axial direction of the elongated three-wavelength fluorescent lamp, and the reflection of the three-wavelength fluorescent lamp on the film sample was visually inspected. The image of the three-wavelength fluorescent lamp reflected on the film sample was evaluated as O if there were heat wrinkles after heating the film sample at 180°C for 15 minutes, or if the image of the three-wavelength fluorescent lamp was distorted or intermittent. If the image of the three-wavelength fluorescent lamp was almost linear, it was evaluated as O. If the image was slightly distorted and / or intermittent, it was evaluated as Δ.

[0141] (Glass Transition Point) The glass transition point (extrapolated onset temperature) of a polymer was measured using a DSC (EXSTAR6000 manufactured by Seiko Instruments Inc.) with a sample amount of 10 mg at a temperature rise rate of 20° C. / min.

[0142] (Example 1) (Acrylic resin (A １ ) and preparation of release layer coating solution) Hexyl acrylate (CH ２ =C(H)COOC ６ H １３ ), hydroxyethyl acrylate (CH ２ =C(H)COOC ２ H ４ OH) were mixed in a molar ratio of 50:50, toluene was added so that the solid content concentration became 40% by mass, and 0.5 mol % of azobisisobutyronitrile (AIBN) was added under a nitrogen gas flow to copolymerize, and an acrylic resin (A １ ) was obtained.

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

[0144] The substrate film used was a polyethylene naphthalate film (manufactured by Toyobo Co., Ltd., Q5100, thickness: 25 μm, area surface average roughness (Sa): 0.006 μm, haze: 12.6%).

[0145] (Formation of Release Layer) The obtained release layer coating liquid was applied to a substrate film using a gravure coater, and then dried at 130° C. for 30 seconds to form a release layer having a thickness of 0.3 μm. The obtained release film was subjected to the above-mentioned evaluations.

[0146] (Example 2) (Acrylic resin (A ２ ) and preparation of release layer coating solution) Octyl acrylate (CH ２ =C(H)COOC ８ H １７), hydroxyethyl acrylate (CH ２ =C(H)COOC ２ H ４ OH) were mixed in a molar ratio of 30:70, toluene was added so that the solid content concentration became 40% by mass, and 0.5 mol % of azobisisobutyronitrile (AIBN) was added under a nitrogen gas flow to copolymerize the mixture, and an acrylic resin (A ２ ) was obtained.

[0147] Acrylic resin A ２ A release layer was formed in the same manner as in Example 1, except that the above-mentioned procedure was changed. The obtained release film was subjected to the above-mentioned evaluations.

[0148] Examples 3 to 10 Release layers were formed in the same manner as in Example 1, except that the compositions were changed to those shown in Table 1. The obtained release films were subjected to the above-mentioned evaluations.

[0149] (Comparative Example 1) (Acrylic Resin (A ３ ) and preparation of release layer coating solution) Butyl acrylate (CH ２ =C(H)COOC ４ H ９ Toluene was added to the mixture so that the solid content concentration became 40% by mass, and 0.5 mol % of azobisisobutyronitrile (AIBN) was added under a nitrogen stream to copolymerize the mixture, and an acrylic resin (A ３ ) was obtained.

[0150] Acrylic resin A ３ A release layer was formed in the same manner as in Example 1, except that the above-mentioned procedure was changed. The obtained release film was subjected to the above-mentioned evaluations.

[0151] (Comparative Example 2) (Acrylic Resin (A ４ ) and preparation of release layer coating solution) Stearyl acrylate (CH ２ =C(H)COOC １２ H ２５ Toluene was added to the mixture so that the solid content concentration became 40% by mass, and 0.5 mol % of azobisisobutyronitrile (AIBN) was added under a nitrogen stream to copolymerize the mixture, and an acrylic resin (A ４ ) was obtained.

[0152] Acrylic resin A ４A release layer was formed in the same manner as in Example 1, except that the above-mentioned procedure was changed. The obtained release film was subjected to the above-mentioned evaluations.

[0153] (Comparative Example 3) (Acrylic Resin (A ５ ) and preparation of release layer coating solution) Stearyl acrylate (CH ２ =C(H)COOC １８ H ３７ Toluene was added to the mixture so that the solid content concentration became 40% by mass, and 0.5 mol % of azobisisobutyronitrile (AIBN) was added under a nitrogen stream to copolymerize the mixture, and an acrylic resin (A ５ ) was obtained.

[0154] Acrylic resin A ５ A release layer was formed in the same manner as in Example 1, except that the above-mentioned procedure was changed. The obtained release film was subjected to the above-mentioned evaluations.

[0155] Comparative Example 4 A polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., E5100, thickness: 38 μm, area surface average 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 manner as in Example 1, except that the release layer coating liquid was applied to the corona-treated surface. The obtained release film was subjected to the above-mentioned evaluations.

[0156] The film-forming conditions and evaluation results for the examples and comparative examples are shown in Tables 1 and 2.

[0157]

[0158]

[0159] <Evaluation Results> According to the examples of the present invention, it is possible to provide a release film in which the resin sheet does not peel off from the release film during pre-drying, and the resin sheet can be peeled off from the release film after drying without deformation or breakage. 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.

[0160] On the other hand, in Comparative Example 1, R in A-1 component of acrylic resin A １ In Comparative Example 2, since n=4, 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 after drying. １ In Comparative Example 3, since n=12, the tape peeling force decreased, and the resin sheet was partially peeled off under the pre-drying conditions. １ In Comparative Example 4, since n = 18, the tape peeling force was significantly reduced and the resin sheet peeled off under the pre-drying conditions. In Comparative Example 4, PET (glass transition point: 80°C) containing no naphthalenedicarboxylic acid was used as the base film, and it was confirmed that the flatness of the film was slightly impaired compared to the present invention.

[0161] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0162] To provide a release film in which a resin sheet does not peel off from the release film during pre-drying, and the resin sheet can be peeled off from the release film after drying without deformation or breakage, and even if the release film is thin, the release film does not deform in a heat step, and the resin sheet does not deform or break.

Claims

1. A release film having a base film and a release layer, wherein the release layer contains an acrylic resin A and a crosslinking agent B, the acrylic resin A contains, as structural units, an A-1 component represented by the following general formula (1) and an A-2 component represented by the following general formula (2), the release layer does not substantially contain a silicone component, and the glass transition point of the resin constituting the base film is 100°C or higher. (In general formula (1), R １ (C ｎ H ２ｎ＋１ ) (n = an integer of 5 or more and 10 or less), R ３ is H or CH ３ Indicates.) (In general formula (2), R ２ (C ｍ H ２ｍ OH) (m = an integer of 1 or more and 10 or less) or H, R ４ is H or CH ３ Indicates.) 2. The release film according to claim 1, wherein the molar ratio of the A-1 component to the total number of moles of the A-1 component and the A-2 component is 30 mol % or more and 90 mol % or less.

3. The release film according to claim 1 or 2, wherein the tape peel strength of the release layer is 5,000 mN / 50 mm or more and 15,000 mN / 50 mm or less at a peel speed of 300 mm / min.

4. The Martens hardness of the base film is 150 N / mm 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 a structural unit derived from naphthalenedicarboxylic acid as a dicarboxylic acid component.

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