TWI808552B - Release film and laminated film - Google Patents

Abstract

The present invention provides a release film, which has light peeling force before and after heating, and can also have light peeling force even in the case of high-speed peeling, and does not contain polysiloxane substantially. The release film of the present invention is characterized in that: a release layer is laminated on the substrate film, and the release layer contains at least a long-chain alkyl-containing acrylic resin (A) and a crosslinking agent (B), and does not substantially contain silicone components; and the ratio a/b of the weight (a) of the long-chain alkyl-containing acrylic resin contained in the release layer to the weight (b) of the crosslinking agent (b) satisfies the formula (I): (I) 0.1≦a/b≦7.0.

Description

Release film and laminated film

The invention relates to a release film.

The release film formed by laminating a release layer on a base material such as a polyethylene film is used for various purposes such as battery structural members, adhesive layer protection (OCA (Optical Clear Adhesive; optical adhesive) protection, adhesive tape protection, etc.), percutaneous absorption type adhesive pharmaceutical separators in the medical field, processing paper used in the manufacturing steps of electronic parts such as ceramic capacitors, and image display members. If a specific example is given, the adhesive sheet is composed of a base material and an adhesive layer, and is used as a film for manufacturing steps of electronic parts and the like. The adhesive sheet is attached to the release film before being used as a process film. On the surface of the release film (the contact surface with the adhesive layer), a release agent layer is provided in order to improve the release property. Examples of the constituent material of the release agent layer include silicone-based release agents, fluorine-based release agents, and long-chain alkyl-based release agents.

Polysiloxane-based release agents have excellent release properties. However, polysiloxane components are easily transferred to the release body, and there are problems such as contamination of polysiloxane and malfunction of electronic equipment, so it is difficult to use in electronic parts. Fluorine-based release agents have excellent release properties and heat resistance. However, there are problems of being expensive and having poor wettability. Long-chain alkyl-based release agents have better wettability than polysiloxane-based release agents and fluorine-based release agents. However, it does not necessarily have sufficient release properties.

In Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2010-144046), as a release agent capable of preventing cissing when the adhesive resin is applied to the release agent and maintaining good peeling performance from the adhesive resin film, a release agent comprising the following poly(meth)acrylate as a main agent is disclosed. Alkyl (meth)acrylate units.

In Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2007-002092 ), as a release agent having lighter release properties than silicone resin release agents and without transferability, a release agent containing an active ingredient is disclosed. The active ingredient is formed by cross-linking a prepolymer formed by copolymerizing at least an alkyl (meth)acrylate and a hydroxyalkyl (meth)acrylate with an isocyanate group-containing compound.

Patent Document 3 (Japanese Patent Laid-Open No. 2014-151481 ) discloses the following laminated polyester film as a release polyester film with little deterioration in release properties due to heat during processing, which is characterized in that at least one side of the polyester film has a coating layer formed of a coating solution containing a release agent and an active methylene-blocked isocyanate compound. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2010-144046. [Patent Document 2] Japanese Patent Laid-Open No. 2007002092. [Patent Document 3] Japanese Patent Laid-Open No. 2014-151481.

[Problem to be Solved by the Invention]

However, in the technology of Patent Document 1, the peeling force is large, and a release agent with a lighter peeling force is required.

In addition, in the technique of Patent Document 2, there is a problem that the wettability of the release agent is insufficient. In the technology of Patent Document 3, there is a problem that the peeling force is heavy after heating, and the increase in peeling force by heating is insufficiently suppressed.

In addition, heat or pressure may be applied to the release film in the manufacturing process of electronic parts, etc. In this case, the long-chain alkyl-based release agent tends to increase the release force after heating. Furthermore, in the case of high-speed peeling in the manufacturing process, the peeling force tends to increase and the peeling force increases. And even if peeling is possible, cohesive failure (cohesive failure) may occur in the release layer, and the release layer components may be transferred to the release-receiving body. Thus, the long-chain alkyl-based release agent has a problem that it cannot fully exhibit the performance as a release agent, and it is desired to improve this problem.

The present invention solves the above problems. For example, it provides a release film that has light peeling force before and after heating, and can have light peeling force even when peeling at high speed, and does not contain polysiloxane substantially. [Means to solve the problem]

The inventors of the present application conducted intensive studies to solve the above-mentioned problems, and as a result, found that the above-mentioned object can be achieved by a release film having the following configuration, and completed the present invention.

That is, the present invention is constituted by the following configurations. [1] A release film, characterized in that: a release layer is laminated on the substrate film, the release layer contains at least a long-chain alkyl-containing acrylic resin (A) and a cross-linking agent (B), and does not substantially contain silicone components; and the ratio a/b of the weight (a) of the long-chain alkyl-containing acrylic resin contained in the release layer to the weight (b) of the cross-linking agent (b) satisfies the formula (I): (I) 0.1≦a/b≦7.0. [2] In one aspect, the release layer of the release film of the present invention further contains a release agent (C), and the ratio c/b of the weight (b) of the crosslinking agent contained in the release layer to the weight (c) of the release agent satisfies the formula (II): (II) 0.1≦c/b≦10.0. [3] In one aspect, the release film of the present invention has a normal peeling force (PF1) of 8000 mN/50 mm or less at a peeling speed of 0.3 m/min. [4] In one aspect, the peeling force (PF2) of the release film of the present invention after heating (90°C, 20h) at a peeling speed of 0.3m/min. is twice or less than the aforementioned normal peeling force (PF1). [5] In one aspect, the peeling force (PF3) of the release film of the present invention after heating (90°C, 20h) at a peeling speed of 30m/min. is 10 times or less than the aforementioned normal peeling force (PF1). [6] In another aspect of the present invention, there is provided a laminated film in which an adhesive layer is laminated on at least one side of the release film of the present invention. [Efficacy of the invention]

According to the present invention, it is possible to provide a release film which has light release properties both before and after heating, and which maintains light release properties even if it is peeled at high speed.

The inventors conducted intensive research and found a release film, which is characterized in that: a release layer is laminated on the substrate film, the release layer contains at least long-chain alkyl-containing acrylic resin (A) and cross-linking agent (B), and does not substantially contain silicone components, and the ratio a/b of the weight (a) of the long-chain alkyl-containing acrylic resin contained in the release layer to the weight (b) of the cross-linking agent satisfies the formula (I): (I) 0.1≦a/b≦7.0; Thereby, the peeling force is light before and after heating, and even if it peels at high speed, it can maintain light peeling. The release film of the present invention is composed of a release layer and a substrate film. The release layer contains at least an acrylic resin (A) containing a long-chain alkyl group and a crosslinking agent (B), and does not substantially contain silicone components.

[Substrate film] The release film in this invention is equipped with the release layer arrange|positioned on the surface of a base material and the said base material. If the release-receiving body is arranged on the release layer of the release film, the release-receiving body can be formed into the same shape as the substrate. In addition, the release layer and the release-receiving system are easy to peel off, so the shape of the release-receiving body can be deformed and maintained in the desired shape. The release layer can be arranged on one side of the surface of the base material, and can also be arranged on both sides.

As a base material, a well-known base material can be used. For example, a resin film formed of polyester such as polyethylene terephthalate and polyethylene naphthalate, polyolefin such as polypropylene, polyimide, or the like can be used as the base material. In particular, from the viewpoint of cost or productivity, a polyester film is preferred, and a polyethylene terephthalate film is further preferred.

The thickness of the substrate is preferably not less than 10 μm and not more than 188 μm, and more preferably not less than 25 μm and not more than 100 μm. With the thickness of the base material being 10 μm or more, deformation caused by heat can be suppressed during production, processing steps, and molding of the base material. On the other hand, if the thickness of the base material is 188 μm or less, the physical properties required for the base material can be satisfied, and the amount of the base material discarded after use can be suppressed, thereby reducing the burden on the environment.

Between the base material and the release layer, an easy-to-adhesive coating for improving adhesion can also be arranged. In addition, a coating layer for imparting slipperiness, heat resistance, antistatic property, etc. may be disposed on the surface of the substrate opposite to the surface on which the release layer is disposed.

The surface average roughness (Sa) of the substrate film used in the present invention on the surface on which the release layer is laminated is preferably in the range of 1 nm to 50 nm, more preferably in the range of 2 nm to 30 nm. The maximum protrusion height (P) of the release layer-laminated surface of the substrate film used in the present invention is preferably 2 μm or less, more preferably 1.5 μm or less. When Sa is 50nm or less and P is 2 μm or less, the uneven thickness of the release layer can be suppressed and the smoothness of the surface of the release layer can be kept constant, thereby reducing the uneven thickness of the release object and suppressing the possibility of cracking from the thin part as the starting point when the release object is peeled from the release film.

The haze of the substrate film used in the present invention is preferably 10% or less, more preferably 5% or less, more preferably 3% or less. When the haze is 10% or less, it is easy to inspect the appearance when processing a release film or processing an adhesive layer on a release film.

[release layer] The release layer in the present invention contains at least long-chain alkyl-containing acrylic resin (A) and crosslinking agent (B), and does not substantially contain polysiloxane components. For example, the release layer can be formed by curing the release layer forming composition containing the long-chain alkyl group-containing acrylic resin (A) and the crosslinking agent (B). In one aspect, the release layer of the present invention further contains a release agent (C).

[adhesive] The adhesive contained in the release layer of the present invention contains an acrylic resin (A) containing a long-chain alkyl group. Moreover, various polymers can be used as a binder contained in the release layer of this invention. The release layer preferably contains polyester resins, alkyd resins, urethane resins, acrylic resins other than the long-chain alkyl group-containing acrylic resin (A), epoxy resins, and the like. Furthermore, the aforementioned resin preferably has a long-chain alkyl group. Although the theoretical analysis has not been completed, the results of repeated experiments can be considered that the long-chain alkyl group in the binder resin can efficiently align the release agent described later on the surface of the release layer. In particular, the long-chain alkyl group-containing acrylic resin (A) of the present invention, for example, can exhibit good wettability to an adhesive composition for forming an adhesive. Furthermore, the long-chain alkyl group-containing acrylic resin (A) of the present invention can provide a release film that has light release properties before and after heating, and maintains light release properties even at high-speed peeling, for the release object such as an adhesive formed on the release layer. In this way, the long-chain alkyl group-containing acrylic resin (A) can contribute to the release property in addition to its function as a binder in the release layer. For example, the molecular weight of the long-chain alkyl-containing acrylic resin (A) is preferably over 500.

In addition, the release layer of the present invention contains long-chain alkyl-containing acrylic resin (A) and does not substantially contain silicone components. Therefore, it is possible to suppress the transfer of the polysiloxane component to the release object, thereby preventing the release object from being polluted by polysiloxane, for example, avoiding malfunctions of electronic equipment caused by the release object. The term "substantially free of silicone components" in this specification means that no silicone components are intentionally added to the components forming the release layer. For example, in the manufacturing steps of the release layer, etc., there may be very little polysiloxane composition that may exist unexpectedly. In consideration of such a situation, the amount of the polysiloxane component contained in the release layer is preferably less than 0.1 parts by mass relative to 100 parts by mass of the release layer.

The long-chain alkyl-containing acrylic resin (A) may be, for example, an acrylic polymer obtained by copolymerizing long-chain alkyl acrylate, or a graft polymer grafted with a long-chain alkyl group, or a block polymer in which a long-chain alkyl group is added to the terminal. The same aspect can also be adopted regarding the polyester resin etc. which may be contained in the matrix. Hereinafter, as an example, the long-chain alkyl group-containing acrylic resin (A) will be described in detail, but the polyester resin etc. which may be contained in the matrix are similarly applicable.

The long-chain alkyl group-containing acrylic resin (A) is preferably obtained by cross-linking a polymer containing an X component represented by the following formula (1) and a Y component represented by the following formula (2).

In formula (1), R ₁ represents (CnH2n+1) (n=an integer of 8 to 20), and R ₄ represents H or CH ₃ .

In formula (2), R ₂ represents (CmH2mOH) (m=integer of 1 to 10) or H, and R ₄ represents H or CH ₃ .

In the formula (1) representing the X component, R ₁ is an alkyl group having a carbon number n of 8 to 20. When the carbon number n is 8 or more, the X component can exhibit good release properties, and it is possible to suppress the adhesiveness of the release layer that may be caused by an alkyl group with a small carbon number. On the other hand, when carbon number n is 20 or less, the flexibility of X component can be maintained, and the wettability of the film surface of a release layer can fully be ensured. The carbon number n is preferably from 10 to 18, and more preferably from 12 to 16. In addition, R ₁ may be either linear or branched. When R ₁ is a straight chain, the peelability of the release layer tends to be light, which is preferable.

In the formula (1) representing the X component, R ₄ is H or CH ₃ , whichever is suitable. As a raw material of X component, the monomer represented by following formula (7) can be used.

In formula (7), R ₁ represents (CnH2n+1) (n=an integer from 8 to 20), and R ₄ represents H or CH ₃ .

As a raw material of X component, lauryl (meth)acrylate, stearyl (meth)acrylate, etc. can be used specifically,.

In R ₂ of the formula (2) representing the Y component, 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 of the present invention can be prevented from becoming sparse, the cohesion of the release layer itself can be suppressed from weakening, and the peeling force can be suppressed 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.

In the formula (2) representing the Y component, R ₄ is H or CH ₃ , whichever is suitable. As a raw material of the Y component, a monomer represented by the following formula (8) can be used.

In formula (8), R ₂ represents (CmH ₂ mOH) (m=an integer ranging from 1 to 10) or H, and R ₄ represents H or CH ₃ .

As a raw material of the Y component, specifically, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc. can be used.

[Crosslinking agent] As the crosslinking agent (B) for forming the release layer of 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, since the cured film is rigid by using melamine, and is excellent in chemical resistance and weather resistance, it is preferable. Cross-linking using aluminum chelate and titanium chelate may not contain metal components depending on the application.

In the present invention, the ratio a/b of the weight (a) of the long-chain alkyl-containing acrylic resin contained in the release layer to the weight (b) of the crosslinking agent satisfies the formula (I): (I) 0.1≦a/b≦7.0. In one aspect, the ratio a/b of the weight (a) of the long-chain alkyl-containing acrylic resin to the weight (b) of the crosslinking agent is 0.2 to 5.0, for example, 0.2 to 4.0, or 0.2 to 2.5. When the ratio a/b of the weight (a) of the long-chain alkyl group-containing acrylic resin to the weight (b) of the cross-linking agent falls within the above range, the long-chain alkyl group-containing acrylic resin (A) and, if necessary, the binder resin added are cross-linked by the cross-linking agent, and the modulus of elasticity of the release layer increases, so that the release force can be further reduced. In addition, after heating, the release component aligned on the surface of the release layer is also fixed by the crosslinking agent, so the increase in peeling force after heating is suppressed. If the ratio a/b of the weight (a) of the long-chain alkyl group-containing acrylic resin to the weight (b) of the crosslinking agent is 0.1 or less, the release component of the adhesive present on the surface of the release layer will be reduced, so for example, in the form of using an adhesive on the release type, the peeling force may increase. In addition, if the ratio a/b of the weight (a) of the long-chain alkyl group-containing acrylic resin to the weight (b) of the crosslinking agent is 7.0 or more, the crosslinking agent will be reduced, so the adhesive will not be sufficiently crosslinked, and the strength of the release layer may become insufficient, and the peeling force may increase. In addition, this problem tends to become more conspicuous when peeling at high speed.

As the melamine-based compound used for the release layer in the present invention, common compounds can be used without any particular limitation. It is preferably obtained by condensing melamine and formaldehyde, and has one or more triazine rings, and methylol and/or alkoxymethyl groups in one molecule. Specifically, compounds obtained by dehydrating and condensing methanol, ethanol, isopropanol, butanol, which are lower alcohols, and methylol melamine derivatives obtained by condensing melamine and formaldehyde to etherify them are preferred. Examples of methylolated melamine derivatives include monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, and hexamethylolmelamine. One type may be used, or two or more types may be used.

The melamine used in this invention can also use a commercial item. 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, Nikal ac MW-390, Nikalac MW-100LM, Nikalac MX-750LM, Nikalac MW-22, Nikalac MS-21, Nikalac MS-11, Nikalac MW-24X, Nikalac MS-001, Nikalac MX-002, Nikalac MX-730, Nikalac MX-750, Nikalac MX-708, Nikalac MX-706, Nikalac MX-042, Nikalac MX-035, Nikalac MX-45, Nikalac MX-43, Nikalac MX-417, Nikalac MX-410 (manufactured by Nippon Carbide Co., Ltd.), etc. Among these, the full ether type methylated melamine resin is preferable in terms of low temperature, curability in a short time, and adhesiveness to a polyester film. As a commercial item, Cymel 303LF, Nikalac MW-30, etc. are mentioned.

In the release layer of the present invention, it is preferable to add an acid catalyst to promote the cross-linking reaction of the melamine-based compound, and it is preferable to add an acid catalyst to the composition for forming the release layer, apply it, and harden it. The acid catalyst to be used is not particularly limited, and an existing acid catalyst can be used, but a sulfonic acid catalyst is preferably used.

As the sulfonic acid-based catalyst, for example, p-toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, trifluoromethanesulfonic acid, etc. can be suitably used. From the viewpoint of reactivity, p-toluenesulfonic acid is particularly suitably used.

The reason is that compared with other acid catalysts such as carboxylic acid, the sulfonic acid catalyst has higher acidity and excellent reactivity, so the release layer can be processed at a lower temperature. Therefore, since the fall of the planarity of a film by the heat at the time of processing, and the deterioration of a winding appearance can be suppressed, it is preferable.

As the sulfonic acid-based catalyst used in the present invention, commercially available ones can also be used. 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 Chemical Co., Ltd.), the same DNNSA series (dinonylnaphthalene (mono)sulfonic acid, manufactured by Kusumoto Chemical Co., Ltd.), the same DDBSA series (dodecylbenzenesulfonic acid, manufactured by Kusumoto Chemical Co., Ltd.), the same p-TSA series (p-toluenesulfonic acid, manufactured by Kusumoto Chemical Co., Ltd. Chemical Industry Co., Ltd.), etc.

[Release agent] In one aspect, the release layer further contains a release agent (C). The release agent used in the present invention preferably contains long-chain alkyl groups that do not contain polysiloxane, preferably low-molecular-weight polyolefin waxes, long-chain alkyl-based additives, higher alcohols, and the like. These structures may be linear or branched. Among these, two or more kinds of materials may be mixed and used.

In one aspect, the ratio c/b of the weight (b) of the crosslinking agent contained in the release layer to the weight (c) of the release agent satisfies the formula (II): (II) 0.1≦c/b≦10.0. For example, as the addition amount of the release agent in the present invention, the ratio c/b of the weight (b) of the crosslinking agent to the weight (c) of the release agent is preferably 7.0 or less, for example, 5.0 or less. In addition, the ratio c/b may be 0.15 or more. By adjusting the release agent/crosslinking agent ratio (c/b) within this range, the release agent components segregate toward the surface of the release layer, thereby reducing the normal peeling force. Furthermore, since the release component aligned on the surface of the release layer after heating is also fixed by the crosslinking agent, the increase in peeling force after heating is suppressed. On the other hand, if the ratio of release agent/crosslinking agent is 10.0 or more, there will be less crosslinking agent, so the release component may not be able to stay on the surface of the release layer during heating, and the release force may become heavier after heating.

The release agent used in the present invention is preferably low molecular weight, and the molecular weight is preferably more than 100 and less than 500. By making the molecular weight of a release agent into the said range, it becomes easy to align to the surface of a release layer, and a peeling force can be made small. On the other hand, when a molecular weight is 100 or more, the release property of a release agent can be exhibited, and the possibility of showing stickiness can be suppressed. In addition, when the molecular weight is 500 or less, the decrease in the solubility of the release agent can be suppressed, the decrease in the planarity of the surface of the release film can be suppressed, and the possibility of damage to the appearance of the obtained release object can be reduced. In addition, in this specification, such a release agent may be called a low molecular weight release agent, for example.

[Low molecular weight polyolefin wax] As the low-molecular-weight polyolefin wax, low-molecular-weight polyolefin waxes such as polyethylene wax and polypropylene wax can be used, for example.

[Long chain alkyl series additives] As the long-chain alkyl-based additive, additives other than the long-chain alkyl group-containing acrylic resin (A) may be added. For example, low-molecular-weight additives having an alkyl chain such as Peel oil 1010 or Peel oil 1010S (all of which are manufactured by Ichisha Oil Industry Co., Ltd.) can be used as appropriate. The above-mentioned release additives are timely added in an amount capable of expressing a predetermined release property.

[higher alcohol] Examples of the higher alcohol include octanol, nonanol, decyl alcohol, undecanol, dodecanol, tridecanol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecanol, stearyl alcohol, eicosanol, behenyl alcohol, etc., which are linear higher alcohols.

The release agent used in the present invention preferably contains reactive functional groups. Since it contains a functional group, the release agent can be fixed to the release layer by reacting with the adhesive component or the cross-linking agent, so the movement of the release layer before and after heating can be suppressed, and good peelability can be exhibited.

Additives such as adhesion improving agents and antistatic agents may be added to the release layer of the present invention as long as the effects of the present invention are not impaired. In addition, in order to improve the adhesion to the substrate, it is also preferable to perform pretreatments such as anchor coat, corona treatment, plasma treatment, and atmospheric pressure plasma treatment on the surface of the polyester film before the release coating layer is provided.

The thickness of the release layer is preferably not less than 0.01 μm and not more than 10 μm, and more preferably not less than 0.05 μm and not more than 1 μm. When 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, when the thickness of the release layer exceeds 10 μm, the usage ratio of the recycled raw material is lowered, which is uneconomical, which is not preferable.

In the present invention, the method of forming the release coating layer is not particularly limited, and the following method can be used: the coating liquid in which the release resin is dissolved or dispersed is spread on one side of the polyester film of the base material by coating, etc., and the solvent etc. are removed by drying, followed by heat drying, thermosetting or ultraviolet curing. At this time, the drying temperature during solvent drying and thermosetting is preferably below 180°C, more preferably below 160°C, most preferably below 140°C. The heating time for solvent drying and thermosetting is preferably 30 seconds or less, more preferably 20 seconds or less, and still more preferably 10 seconds or less. When the temperature is below 180°C, the planarity of the film is maintained, and the risk of uneven thickness of the release layer is small, which is better. If it is 140 degrees C or less, since it can process without impairing the planarity of a film, and the possibility of causing the thickness unevenness of a release layer will be further reduced, it is especially preferable.

In the present invention, although not particularly limited, it is preferable to add a solvent having a boiling point of 70° C. or higher to the coating liquid at the time of coating the release coating layer. By adding a solvent with a boiling point of 70°C or higher, bumping during drying can be prevented, the coating can be leveled, and the flatness of the surface of the coating after drying can be improved. As the addition amount of this solvent, it is preferable to add about 50 mass % to 99 mass % with respect to the whole coating liquid.

As the coating method of the above-mentioned coating solution, any known coating method can be applied, for example, conventionally known methods such as roll coating such as gravure coating or reverse coating, bar coating such as wire bar, die coating, spray coating, and air knife coating can be used.

The release film obtained in the present invention preferably has a normal peeling force, peeling force after heating, and peeling force at high-speed peeling after heating within the ranges shown below.

In one aspect, the normal peeling force (PF1) of the release film obtained in the present invention is 8000mN/50mm or less at a peeling speed of 0.3m/min., for example, the normal peeling force is from 6000mN/50mm to 8000mN/50mm, for example, from 6000mN/50mm to 7500mN/50mm, or from 6000mN/50mm to 70 00mN/50mm or less. If it is in the said range, it is preferable since normal peeling force is light. If the normal peeling force is 6000mN/50mm or more, the possibility of peeling off the release object during the conveying step is low, which is preferable. If the peeling force before heating is 8000mN/50mm or less, the possibility of deformation of the release body is low when the release body is peeled off, which is preferable. The normal peeling force means the normal peeling force at a peeling speed of 0.3 m/min., and can be evaluated for the peeling force when peeling off a release object disposed on the release layer of the present invention, such as an adhesive (as an example, an acrylic adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 31B), etc.). In addition, the measurement of the normal peel force can be carried out at normal temperature (25°C). The same release type can be applied to the following peeling force after heating.

In one aspect, the peeling force (PF2) after heating (90°C, 20h) at a peeling speed of 0.3m/min. is less than twice the normal peeling force (PF1). If the post-heating peeling force (PF2) is twice or less than the normal peeling force, the post-heating peeling force is low, which is preferable. The peeling force after heating (PF2) is more preferably 1.7 times or less of the normal peeling force (PF1), most preferably 1.5 times or less. If the peeling force after heating is less than twice the normal peeling force, it is preferable that the release body does not deform when the release body is peeled off after heating. In addition, in the present invention, the post-heating peeling force (PF2) may be 6000 mN/50 mm or more, and the possibility of peeling off the release object during the conveying step is low, which is preferable.

In one aspect, the peeling force (PF3) after heating (90°C, 20h) at a peeling speed of 30m/min. is less than 10 times the normal peeling force (PF1). By having such a relationship, it is preferable that the high-speed peeling force after heating is low. The peel force (PF3) is further preferably 7 times or less, more preferably 5 times or less, the normal peel force (PF1). If the peeling force (PF3) is less than 10 times of the normal peeling force (PF1), then when the release body is peeled off at high speed after heating, the possibility of deformation of the release body is low, which is preferable.

In the present invention, a laminated film can be obtained by providing an adhesive layer on at least one surface of a release film. The laminated film can be obtained, for example, by coating an adhesive composition on at least one side of the release film of the present invention, drying as necessary, and forming an adhesive layer on at least one side of the substrate. For example, an adhesive layer may be provided on the surface opposite to the substrate in the release layer.

The present invention is not limited to adhesive sheets, but can also be applied to structural members for batteries, protection of adhesive layers (protection for OCA, protection for adhesive tapes, etc.), percutaneous absorption type adhesive pharmaceutical separators in the medical field, process paper used in the manufacturing steps of electronic parts such as ceramic capacitors, protection of members for image display, and other uses. Regarding the effect, the same effect can also be expected. [Example]

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited by these examples. The characteristic values used in the present invention were evaluated using the following methods.

[evaluate] [Normal Peel Force (PF1)] Attach an adhesive tape ("31B" manufactured by Nitto Denko Co., Ltd.) to the surface of the release film, press it with a pressure roller with a linear pressure of 5kgf/mm, and place it at a temperature of 22°C and a humidity of 60% for 20 hours. Cut the release film attached with the adhesive tape into short strips with a width of 25mm and a length of 150mm. Fix one end of the adhesive tape, hold one end of the release film, stretch the side of the release film at a speed of 300mm/min., and measure the T-peel strength. A tensile tester ("AUTOGRAPHAG-X" manufactured by Shimadzu Corporation) was used for the measurement. The results are shown in Table 1.

[Peel force after heating (PF2)] Adhesive tape (manufactured by Nitto Denko Co., Ltd., trade name "31B") was attached to the surface of the release film. After crimping with a pressure roller with a linear pressure of 5kgf/mm, the release film with the adhesive tape attached was cut into short strips with a width of 25mm and a length of 150mm, and heated in an oven at a temperature of 90°C for 20 hours. Then, fix one end of the adhesive tape, hold one end of the release film, stretch the side of the release film at a speed of 300mm/min. to peel off, and measure the T-peel strength. For the measurement of the T-peel strength, a tensile tester ("AUTOGRAPHAG-X" manufactured by Shimadzu Corporation) was used. The results are shown in Table 1.

[High speed peel force after heating (PF3)] Adhesive tape (manufactured by Nitto Denko Co., Ltd., trade name "31B") was attached to the surface of the release film. After crimping with a pressure roller with a linear pressure of 5kgf/mm, the release film with the adhesive tape attached was cut into short strips with a width of 25mm and a length of 150mm, and heated in an oven at a temperature of 90°C for 20 hours. Then, fix the release film side to the metal plate with double-sided tape, hold one end of the adhesive tape, stretch the adhesive tape side at a speed of 30m/min. to peel off, and measure the 180°peel strength. In the measurement of the 180° peel strength, a tensile tester ("High Speed Peel Tester TE-701" of Tester Sangyo Co., Ltd.) was used. The results are shown in Table 1.

[Preparation of adhesive and release layer coating solution] Mix lauryl methacrylate (CH ₂ =C(CH ₃ )COOC ₁₂ H ₂₅ ), hydroxyethyl methacrylate (CH ₂ =C(CH ₃ )COOC ₂ H ₄ OH), and methyl methacrylate (CH ₂ =C(CH ₃ )COOCH ₃ ) at a ratio of 50:30:20, and add so that the solid content becomes 40% by weight Add 0.5 mol% of azobisisobutyronitrile (AIBN) to toluene under a nitrogen stream for copolymerization to obtain an acrylic resin containing long-chain alkyl groups.

[Example 1] Add an acrylic resin containing a long-chain alkyl group, a melamine resin as a cross-linking agent (manufactured by Nippon Denshi Co., Ltd., Nikalac MW-30), a high-molecular-weight release agent (manufactured by Tokyo Chemical Industry Co., Ltd., pentadecyl alcohol), and p-toluenesulfonic acid as a hardening catalyst (manufactured by Hitachi Chemical Polymer Co., Ltd., Dryer#900) in the amount described in Table 1, and then add a solvent (toluene/MEK (methyl ethyl ketone; methyl ethyl ketone) =50/50: mass ratio), the solid content concentration was 6.0 mass %, and the release layer coating liquid was obtained.

[Formation of release layer] The obtained release layer coating solution was coated on the corona-treated surface of polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., E5100, thickness: 38 μm, surface roughness (Sa): 0.0365 nm (corona-treated surface), maximum surface section height (St): 3.72, haze: 3.7%), and dried at 130° C. for 30 seconds to form a release layer with a thickness of 0.2 μm. . For the obtained release film, the normal peeling force, the peeling force after heating, and the high-speed peeling force after heating were evaluated.

[Example 2 to Example 5, Comparative Example 1, Comparative Example 2] Except having changed the composition into the composition of Table 1, the release layer was formed in the same procedure as Example 1. For the obtained release film, the normal peeling force, the peeling force after heating, and the high-speed peeling force after heating were evaluated.

[Table 1] weight ratio(%) Relative to the ratio of crosslinking agent Peel force (mN/50mm) Ratio relative to PF1 Adhesive (a) Crosslinking agent (b) Release agent (c) catalyst a/b c/b Normal (PF1) After heating (PF2) High speed after heating (PF3) PF2/PF1 PF3/PF1 Example 1 37.4 45.6 15.0 1.9 0.8 0.3 6579 9741 31126 1.5 4.7 Example 2 37.4 25.6 35.1 1.9 1.5 1.4 6312 7639 20035 1.2 3.2 Example 3 37.4 15.6 45.1 1.9 2.4 2.9 6602 7310 14999 1.1 2.3 Example 4 37.4 10.6 50.1 1.9 3.5 4.7 7018 8378 20183 1.2 2.9 Example 5 76.9 21.2 0.0 1.9 3.6 0.0 6453 8765 26453 1.4 4.1 Comparative example 1 37.4 5.0 55.6 1.9 7.5 11.1 9561 21554 Can't peel off 2.3 Can't peel off Comparative example 2 37.4 0.0 60.6 1.9 0.0 0.0 Can't peel off Can't peel off Can't peel off Can't peel off Can't peel off

[Evaluation results] According to the present invention, it is possible to provide a release film which has light release properties both before and after heating, and which maintains light release properties even if it is peeled at high speed. On the other hand, in Comparative Example 1, the ratio a/b of the weight (a) of the long-chain alkyl group-containing acrylic resin to the weight (b) of the crosslinking agent is outside the scope of the present invention, so the high-speed peeling force (PF3) after heating cannot be measured. Furthermore, the peeling force increased after heating, and the release layer and the adhesive tape could not be peeled off. In addition, since Comparative Example 2 does not contain a crosslinking agent (B), the adhesive tape cannot be peeled from the release layer even at normal temperature.

It should be considered that the embodiments and examples disclosed this time are illustrative in all points and not restrictive. The scope of the present invention is shown by the claims rather than the above-mentioned embodiments, and it is intended that all modifications within the meaning and range equivalent to the claims are included. [Industrial availability]

The release film of the present invention can be more suitably used in the manufacturing steps of electronic parts where it is difficult to use a polysiloxane release film.

Claims (7)

A release film, which is laminated with a release layer on a substrate film, the release layer at least contains an acrylic resin (A) containing a long-chain alkyl group with a carbon number of 8 to 20, a crosslinking agent (B) and a release agent (C), and does not substantially contain silicone components; the aforementioned crosslinking agent (B) is melamine; the molecular weight of the aforementioned release agent (C) is 100 to 500; The ratio a/b of the weight (a) of the acrylic resin of the alkyl group to the weight (b) of the crosslinking agent satisfies the formula (I): (I) 0.1≦a/b≦7.0. The release film as described in Claim 1, wherein the ratio c/b of the weight (b) of the crosslinking agent contained in the release layer to the weight (c) of the release agent satisfies the formula (II): (II) 0.1≦c/b≦10.0. The release film as described in claim 1 or 2, wherein the normal peeling force (PF1) at a peeling speed of 0.3m/min. is 8000mN/50mm or less. The release film as described in claim 3, wherein the peeling force (PF2) after heating (90°C, 20h) at a peeling speed of 0.3m/min. is less than twice the normal peeling force (PF1). The release film as described in claim 3, wherein the peeling force (PF3) after heating (90°C, 20h) at a peeling speed of 30m/min. is less than 10 times the normal peeling force (PF1). The release film as described in claim 4, wherein the peeling force (PF3) after heating (90°C, 20h) at a peeling speed of 30m/min. is less than 10 times the normal peeling force (PF1). A laminated film comprising an adhesive layer laminated on at least one side of the release film as described in any one of claims 1 to 6 above.