Release film and laminate

Abstract

A novel release film is provided, as well as a laminate produced using such a release film. [Solution] A release film having a substrate and a release layer formed on one side of the substrate, the release layer containing a binder resin and a surface modifier having a reactive functional group, the reactive functional group being at least one selected from the group consisting of an epoxy group and a phenolic hydroxyl group, and the binder resin not having a specific functional group that forms a covalent bond with the reactive functional group.

Description

[Technical Field]

[0001] The present invention relates to a release film and a laminate. [Background technology]

[0002] Conventionally, release films having a release layer have been used. For example, Patent Document 1 describes a release film (release film) having a release layer with controlled surface roughness and used for simultaneous molding and transfer applications. When the release film of Patent Document 1 is used, when molding a resin molded product, it is possible to transfer a transfer foil onto the surface of the molded product at the same time as molding, thereby providing decoration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6205874 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors considered that if it were possible to transfer a surface modifier that improves the surface properties onto the surface of a molded article, similar to the use of a release film to decorate a molded article as described in Patent Document 1, the degree of freedom in adjusting the physical properties of the molded article would increase. Generally, when modifying the surface of a molded article, a layer of surface modifier is formed on the molded article. However, forming a layer of surface modifier on the surface of a molded article to create a multilayer structure can make production complicated.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel release film and a laminate produced using such a release film. [Means for solving the problem]

[0006] The inventors came up with the idea of ​​incorporating a surface modifier into the release layer of a release film and molding a resin molded product on the release layer, thereby transferring the surface modifier from the release layer to the resin molded product. They have confirmed that this method allows the surface modifier to be transferred to the surface of the molded product.

[0007] However, in this method, the surface modifier is only physically attached to the surface of the molded article, which tends to make the transfer unreliable, and the surface modifier may come off when the surface of the molded article is rubbed after transfer. Therefore, there is room for improvement in the above invention.

[0008] In order to solve the above problems, one aspect of the present invention includes the following aspects.

[0009] [1] A release film having a substrate and a release layer formed on one surface of the substrate, the release layer containing a binder resin and a surface modifier having a reactive functional group, the reactive functional group being at least one selected from the group consisting of an epoxy group and a phenolic hydroxyl group, and the binder resin not having a specific functional group that forms a covalent bond with the reactive functional group.

[0010] [2] The release film according to [1], wherein the binder resin comprises a curable resin of an acrylic polyol resin and a crosslinking agent.

[0011] [3] The release film according to [1] or [2], wherein the reactive functional group is an epoxy group.

[0012] [4] A release film according to any one of [1] to [3], wherein the content of the surface modifier in the release layer is lower on the substrate side than on the surface side of the release layer.

[0013] [5] A laminate comprising the release film according to any one of [1] to [4] and a molded article in contact with the release layer, wherein the molded article has the specific functional group. [Effects of the Invention]

[0014] According to the present invention, a novel release film can be provided, and a laminate produced using such a release film can also be provided. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the release film of this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a method for producing a release film. [Figure 3] FIG. 3 is a schematic diagram showing a method for producing a release film. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the laminate of this embodiment. [Figure 5] FIG. 5 is a schematic cross-sectional view showing the laminate of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] The release film and laminate according to this embodiment will be described below with reference to Figures 1 to 5. In all of the following figures, the dimensions and proportions of the components have been changed as appropriate to make the drawings easier to understand.

[0017] [Release film] 1 is a schematic cross-sectional view showing a release film 1 of this embodiment. As shown in Fig. 1, the release film 1 has a substrate 10 and a release layer 20 formed on one surface 10a of the substrate 10.

[0018] <Base material> The substrate 10 supports the release layer 20 and ensures the rigidity of the entire release film 1. The material of the substrate 10 is not particularly limited, but examples include polyester resins such as polyethylene terephthalate (PET) and polyarylate, polyamide resins such as nylon, polyolefin resins such as polyethylene, polypropylene and polymethylpentene, cyclic olefin resins, acrylic resins such as polymethyl methacrylate (PMMA), polyimide resins such as polyetherimide, resin films such as polyvinyl chloride, polystyrene, polycarbonate (PC), polyether ether ketone, polysulfone, polyethersulfone, fluorine-based resins, polyphenylene sulfide, and polyurethane.

[0019] When the substrate 10 is a resin film, it may be an unstretched film or a uniaxially or biaxially stretched film. The stretching ratio and stretching direction of the stretched film can be appropriately set. The thickness of the substrate is not particularly limited, but is preferably 10 to 100 μm, more preferably 38 to 70 μm.

[0020] <Release layer> The release layer 20 contains a binder resin 21 and a surface modifier 22. The content (concentration) of the surface modifier 22 in the release layer 20 is preferably lower on the substrate 10 side than on the surface side of the release layer 20. In the release layer 20 shown in FIG. 1, the concentration of the surface modifier 22 gradually decreases from the surface 20a of the release layer 20 toward the substrate 10.

[0021] As will be described in detail later, the release layer 20 can be produced by applying a mixed solution containing a binder resin precursor and a surface modifier to the surface of a substrate to form a coating film, and then drying the coating film. During this process, the drying removes the solvent from the coating film. This relatively increases the concentration of the curing agent in the coating film, accelerating the crosslinking or curing reaction of the precursor. As the reaction progresses, the binder resin 21 produced by the reaction of the precursor bonds with the surface 10a of the substrate 10 and becomes more likely to be present on the substrate 10 side. The surface modifier 22 is relatively pushed toward the surface 20a of the release layer 20, and separation between the binder resin 21 and the surface modifier 22 progresses. As a result, the content of the surface modifier 22 in the resulting release layer 20 gradually decreases from the surface 20a of the release layer 20 toward the substrate 10.

[0022] 1, the concentration distribution of the surface modifier 22 is shown by the shading of the release layer 20, with higher concentrations being darker. A method for producing the release layer 20 will be described later.

[0023] (binder resin) The binder resin 21 is a material that forms the release layer 20 and holds the surface modifier 22. The binder resin 21 does not have a specific functional group that forms a covalent bond with a reactive functional group (described later) possessed by the surface modifier 22. Note that "does not have a specific functional group" means that the binder resin 21 does not have any specific functional groups at all, or that even if it does have a specific functional group, the amount is so small that it does not actually cause any problems.

[0024] The specific functional group may be at least one selected from the group consisting of an epoxy group, a phenolic hydroxyl group, a cyanate ester group, and an active ester group.

[0025] The activated ester group refers to an ester bond having an electron-withdrawing group such as an aromatic ring on the oxygen atom derived from a hydroxyl group among the oxygen atoms in the ester bond. Specific examples include compounds having an allyloxycarbonyl allyl structure. The two allyl groups in the allyloxycarbonyl allyl may have the same structure or different structures. Furthermore, the two allyl groups may each independently have a substituent such as an alkyl group, a hydroxyl group, a carboxyl group, or an alkyl ester group.

[0026] As a result, in the release layer 20, the binder resin 21 does not react or does not substantially react with the surface modifier 22, and retains the surface modifier 22 by being mixed with the surface modifier 22.

[0027] "Substantially no reaction" means that either one or both of the following (1) and (2) is met, and as a result, no covalent bond is formed between the binder resin 21 and the surface modifier 22 to an extent that would impair the effect of the invention. (1) Under the reaction conditions (curing conditions) of the binder resin 21, the reaction between the specific functional group of the binder resin precursor and the reactive functional group of the surface modifier 22 hardly proceeds. (2) The reaction between the specific functional group of the binder resin 21 and the reactive functional group of the surface modifier 22 hardly proceeds.

[0028] As the binder resin 21, various known materials can be used, but among them, at least one selected from the group consisting of a curable resin containing an acrylic polyol resin as a main component, an amino alkyd resin, or a melamine resin is preferred.

[0029] (A curable resin with acrylic polyol resin as the main component) The curable resin containing an acrylic polyol resin as a main component is a curable resin obtained by reacting an acrylic polyol resin with a crosslinking agent.

[0030] Acrylic polyol resin is a polymer in which multiple hydroxyl groups have been introduced into an acrylic copolymer. Commercially available acrylic polyol resin products include Acrydic manufactured by DIC Corporation, Thermolac manufactured by Soken Chemical & Engineering Co., Ltd., and Acrit manufactured by Taisei Fine Chemical Co., Ltd.

[0031] (Crosslinking agent) The crosslinking agent may be a compound capable of reacting with the hydroxyl groups of the acrylic polyol resin to form a crosslinked structure, such as a melamine compound, an oxazoline compound, a carbodiimide compound, or an isocyanate compound.

[0032] (melamine compounds) The melamine compound refers to a compound having a melamine skeleton therein, and examples thereof include alkylolated melamine derivatives, compounds obtained by reacting alkylolated melamine derivatives with alcohols to partially or completely etherify them, and mixtures thereof.

[0033] As the alcohol used for etherification of the alkylolated melamine derivative, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol, etc. are preferably used.

[0034] The melamine compound may be a monomer or a dimer or higher polymer. The melamine compound may also be a mixture of these. Furthermore, the melamine compound may also be a compound obtained by co-condensing melamine with urea or the like.

[0035] When a melamine compound is used as the crosslinking agent, a catalyst may be used to increase the reactivity of the melamine compound.

[0036] (Oxazoline compounds) The oxazoline compound refers to a compound having an oxazoline group in the molecule. As the oxazoline compound, a polymer containing an oxazoline group is particularly preferred. The polymer containing an oxazoline group can be obtained by homopolymerization of an addition-polymerizable oxazoline group-containing monomer or copolymerization of an addition-polymerizable oxazoline group-containing monomer with another monomer.

[0037] Examples of the addition-polymerizable oxazoline group-containing monomer include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline, and these can be used alone or in combination. Among these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.

[0038] The other monomer is not limited as long as it is copolymerizable with the addition-polymerizable oxazoline group-containing monomer, and examples of such monomers include (meth)acrylic acid esters, unsaturated carboxylic acids, unsaturated nitriles, unsaturated amides, vinyl ethers, halogen-containing α,β-unsaturated monomers, and α,β-unsaturated aromatic monomers.

[0039] Examples of the alkyl group (the alkyl group portion of the alkoxy group) contained in the (meth)acrylic acid esters include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, and a cyclohexyl group.

[0040] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid, and salts of these compounds. Examples of unsaturated carboxylic acid salts include sodium salts, potassium salts, ammonium salts, and tertiary amine salts.

[0041] Examples of unsaturated nitriles include acrylonitrile and methacrylonitrile.

[0042] Examples of unsaturated amides include (meth)acrylamide, N-alkyl(meth)acrylamide, and N,N-dialkyl(meth)acrylamide. Examples of the alkyl group contained in N-alkyl(meth)acrylamide and N,N-dialkyl(meth)acrylamide include ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl groups.

[0043] Examples of vinyl ethers include vinyl esters such as vinyl acetate and vinyl propionate; methyl vinyl ether; and ethyl vinyl ether.

[0044] Examples of the α-olefins include ethylene and propylene.

[0045] Examples of halogen-containing α,β-unsaturated monomers include vinyl chloride and vinylidene chloride.

[0046] Examples of the α,β-unsaturated aromatic monomer include styrene and α-methylstyrene.

[0047] The above-mentioned other monomers may be used alone or in combination of two or more.

[0048] (Carbodiimide compounds) A carbodiimide compound is a compound having a carbodiimide structure, and refers to a compound having one or more carbodiimide structures in the molecule. In order to impart better adhesion to the binder resin, a polycarbodiimide compound having two or more carbodiimide structures in the molecule is preferred.

[0049] Carbodiimide compounds can be synthesized by conventionally known techniques. For example, polycarbodiimide compounds having two or more carbodiimides in a molecule can be obtained by a condensation reaction of a diisocyanate compound.

[0050] The diisocyanate compound is not particularly limited, and either an aromatic or aliphatic diisocyanate can be used. Specific examples include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate.

[0051] (Isocyanate compounds) The isocyanate compound refers to a compound (isocyanate) having an -N=C=O group in the molecule, or a compound having an isocyanate derivative structure, such as a blocked isocyanate.

[0052] Examples of the isocyanate include aromatic isocyanates, aliphatic isocyanates having an aromatic ring, and aliphatic isocyanates.

[0053] Examples of aromatic isocyanates include tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate.

[0054] Examples of the aliphatic isocyanate having an aromatic ring include α,α,α',α'-tetramethylxylylene diisocyanate.

[0055] The aliphatic hydrocarbon group contained in the aliphatic isocyanate may be linear, branched, or cyclic (alicyclic).

[0056] Examples of the aliphatic isocyanate having a linear or branched structure include methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate.

[0057] Examples of the aliphatic isocyanate having a cyclic structure include cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), and isopropylidenedicyclohexyl diisocyanate.

[0058] Further examples include biuretized products, isocyanurate products, urethodionated products and carbodiimide modified products of the above isocyanates, polyisocyanates which are polymers of isocyanates, and blocked isocyanates which are derivatives of isocyanates.

[0059] A blocked isocyanate is an isocyanate in which the isocyanate group has been blocked with a blocking agent. A blocking agent is an active hydrogen compound that can react reversibly with an isocyanate group. The blocking agent inactivates (protects) the isocyanate group by reacting with it. Furthermore, when the isocyanate group blocked with a blocking agent is heated, the blocking agent dissociates (deprotects), restoring the reactivity of the isocyanate group.

[0060] The blocking agent is not particularly limited, and for example, a phenol-based compound, a lactam-based compound, an active methylene-based compound, an alcohol-based compound, an oxime-based compound, a mercaptan-based compound, an imide-based compound, or a secondary amine-based compound can be used.

[0061] Examples of the phenolic compounds include phenol, cresol, xylenol, chlorophenol, and ethylphenol.

[0062] Examples of lactam compounds include ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam.

[0063] Examples of the active methylene compounds include ethyl acetoacetate and acetylacetone.

[0064] Examples of alcohol compounds include methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, t-butanol, amyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol mono-2-ethylhexyl ether, propylene glycol monomethyl ether, methyl glycolate, butyl glycolate, diacetone alcohol, methyl lactate, ethyl lactate, and furfuryl alcohol.

[0065] Examples of the oxime compounds include formaldoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, and cyclohexane oxime.

[0066] Examples of the mercaptan compounds include butyl mercaptan, hexyl mercaptan, t-butyl mercaptan, thiophenol, methylthiophenol, and ethylthiophenol.

[0067] Examples of imide compounds include acid amides such as acetic acid amide and benzamide, succinic acid imide, and maleic acid imide.

[0068] Examples of secondary amine compounds include imidazoles such as imidazole and 2-ethylimidazole, dimethylamine, diethylamine, and dibutylamine.

[0069] The above-mentioned isocyanate compounds may be used alone or in combination of two or more.

[0070] When an isocyanate is used as the crosslinking agent, an aliphatic isocyanate or an alicyclic isocyanate is preferred in order to prevent yellowing due to ultraviolet light.

[0071] (amino alkyd resin) Aminoalkyd resins are synthetic resins whose main components are a mixture of alkyd resins and amino resins.

[0072] Alkyd resin refers to a thermosetting resin that has a skeleton made from a condensate of a polybasic acid and a polyhydric alcohol, and is modified with oil, fatty acid, rosin acid monomer, or the like.

[0073] Examples of polybasic acids that constitute alkyd resins include phthalic anhydride, isophthalic acid, terephthalic acid, benzoic acid, rosin, 1,2,3,6-tetrahydrophthalic anhydride, maleic anhydride, adipic acid, and succinic acid.

[0074] Examples of polyhydric alcohols that constitute alkyd resins include glycerin, pentaerythritol, ethylene glycol, propylene glycol, neopentyl glycol, and trimethylolpropane.

[0075] Examples of the amino resin include alkylated melamine resin and urea resin. Examples of the alkylated melamine resin include methylated melamine resin, butylated melamine resin, and methylated butylated melamine resin.

[0076] Commercially available aminoalkyd resin products include Tesfine (Showa Denko Materials Co., Ltd.).

[0077] (melamine resin) Melamine resin is a curable resin obtained by polycondensation of melamine and formaldehyde. Methylol groups may be partially methylated or butylated.

[0078] Commercially available melamine resin products include Cymel 300, 303, 325, 350, and 370 (manufactured by Allnex).

[0079] Furthermore, various materials used in known release films can be used as the binder resin, as long as they do not react or do not substantially react with the surface modifier 22. For example, the binder resin can include resins such as polyester resin, acrylic resin, and urethane resin. The binder resin preferably contains functional groups that serve as crosslinking points for the crosslinking agent.

[0080] (polyester resin) The polyester resin is a polymer having an ester bond in the main chain or side chain, and is obtained by polycondensation of a dicarboxylic acid and a diol.

[0081] The dicarboxylic acid may be an aromatic or aliphatic dicarboxylic acid or an ester-forming derivative thereof. The aliphatic hydrocarbon group of the aliphatic dicarboxylic acid may be linear, branched, or cyclic.

[0082] Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bisphenoxyethane-p-p'-dicarboxylic acid, and phenylindanedicarboxylic acid.

[0083] Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.

[0084] Diol components include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexamethyl Examples of suitable cyclohexanediol include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A, 4,4'-methylenediphenol, 4,4'-(2-norbornylidene)diphenol, 4,4'-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenebindiol, cyclopentane-1,2-diol, cyclohexane-1,2'-diol, cyclohexane-1,2-diol, and cyclohexane-1,4-diol.

[0085] These monomers may be used alone or in combination of two or more.

[0086] Furthermore, as the polyester resin, it is also possible to use modified polyester copolymers, for example, block copolymers and graft copolymers modified with acrylic, urethane, epoxy, or the like.

[0087] (acrylic resin) Although not particularly limited, acrylic resins are obtained by polymerizing or copolymerizing (meth)acrylic acid or alkyl (meth)acrylate. Note that "(meth)acrylic acid" refers to either or both of acrylic acid and methacrylic acid, and "alkyl (meth)acrylate" refers to either or both of alkyl acrylate and alkyl methacrylate.

[0088] Examples of (meth)acrylic acid or alkyl (meth)acrylates include methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, maleic acid, itaconic acid, acrylamide, N-methylolacrylamide, and diacetone acrylamide.

[0089] These monomers may be used alone or in combination of two or more.

[0090] (urethane resin) The urethane resin can be obtained by polymerizing a polyhydroxy compound and a polyisocyanate compound by a known method.

[0091] Examples of polyhydroxy compounds include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, polycarbonate diol, and glycerin.

[0092] Examples of polyisocyanate compounds that can be used include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, an adduct of tolylene diisocyanate and trimethylenepropane, and an adduct of hexamethylene diisocyanate and trimethylolethane.

[0093] These monomers may be used alone or in combination of two or more.

[0094] The binder resin 21 described above may be used alone or in combination of two or more kinds.

[0095] The binder resin 21 may contain a release agent used in known release films. Examples of the release agent include silicone-based release agents and non-silicone-based release agents. "Non-silicone-based" means that the molecular structure of the compound that makes up the release agent does not contain a silicone bond (Si-O-Si).

[0096] (surface modifier) Surface modifier 22 is a material that is transferred to the surface of a molded article formed using release film 1 and has the function of modifying the surface properties of the molded article. Properties that can be modified by surface modifier 22 include the contact angle (water repellency), antifouling properties, oil repellency, hydrophilicity, adhesiveness, and antistatic properties of the molded article surface.

[0097] (reactive functional group) The surface modifier 22 has a main skeleton (molecular structure) that achieves the desired surface modification and a reactive functional group bonded to the main skeleton, the reactive functional group being at least one selected from the group consisting of an epoxy group and a phenolic hydroxyl group.

[0098] Since the surface modifier 22 has a reactive functional group (e.g., an epoxy group), the reactive functional group is expected to react with the surface of the molded body, forming a strong bond between the surface modifier 22 and the molded body. This makes it easier for the surface modifier 22 to be transferred to the surface of the molded body. In addition, the surface modifier 22 transferred to the surface of the molded body is less likely to be removed by rubbing, making it easier for the surface properties of the molded body to be stabilized.

[0099] Regarding whether the surface modifier 22 contained in the release layer 20 has a reactive functional group, the release layer 20 is immersed in chloroform to elute the surface modifier 22 into the chloroform, and then the presence of the reactive functional group in the eluted surface modifier 22 is confirmed by, for example, NMR ( 1 H-NMR, 13 This can be confirmed by detecting the reactive functional groups using C-NMR. By detecting the reactive functional groups, the presence of a surface modifier having a reactive functional group can be confirmed.

[0100] The method for confirming the reactive functional group is not limited to NMR, and various methods can be used as long as they are capable of detecting the reactive functional group.

[0101] (Main skeleton) The main skeleton of the surface modifier 22 can be appropriately selected depending on the properties that the surface modifier 22 imparts (modifies) to the molded article.

[0102] For example, when modifying the water repellency of the surface of a molded article, the main skeleton of the surface modifier 22 is preferably an alkyl pendant polymer or an acrylic material (acrylic polymer).

[0103] The alkyl pendant polymer has a side chain with an alkyl group attached to the main chain. Examples of the main chain of the alkyl pendant polymer include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyethyleneimine, acrylic resin, and polyester resin. If necessary, a linking group such as an ester group (-COO-), an amide group (-CONH-), an ether group (-O-), or a urethane group (-NHCOO-) may be introduced between the main chain of the polymer and the alkyl group on the side chain.

[0104] Alkyl pendant polymers can also be obtained by reacting a main chain having a functional group such as a hydroxyl group (-OH), an amino group (-NH), or an imino group (-NH-) with a compound having an alkyl group. For example, an alkyl pendant polymer can be obtained by reacting a compound in which a functional group such as an isocyanate group or an epoxy group is bonded to an alkyl group with the functional group of the main chain. In this case, the linking group between the main chain and the alkyl group is formed by the reaction between the functional group of the main chain and the functional group of the side chain.

[0105] Specifically, for example, an alkyl pendant polymer may be obtained by adding an alkyl isocyanate to the hydroxyl group of polyvinyl alcohol.

[0106] The alkyl pendant polymer can also be obtained by synthesizing a polymer using a monomer having an alkyl group and a functional group that forms a main chain, such as a vinyl group. In this case, a linking group between the main chain and the alkyl group may be introduced from the monomer stage. For example, an alkyl group-containing monomer, such as alkyl acrylate, alkyl methacrylate, alkyl vinyl ether, or alkyl allyl ether, having an alkyl group, may be copolymerized with another vinyl monomer.

[0107] In the alkyl pendant polymer, the alkyl group in the side chain may be linear or branched. The number of carbon atoms in the alkyl group may be, for example, 6 to 30, such as 10 to 24 or 12 to 18. When an alkyl group derived from a fatty acid such as fat or oil is used in the side chain, the alkyl pendant polymer may be a mixture of alkyl groups with different numbers of carbon atoms.

[0108] The alkyl pendant polymer preferably has solvent resistance corresponding to the resin layer (described later) such as a cast resin formed on the release layer. For example, in the case of a polar solvent such as ethyl acetate, the solvent resistance can be improved by using an alkyl pendant polymer having a long-chain alkyl group.

[0109] When the material used to form the resin layer (precursor of the binder resin) contains an additive having an active functional group such as an isocyanate-based crosslinking agent, it is preferable that the alkyl pendant polymer does not have a functional group such as a hydroxyl group that can react with the functional group of the precursor of the binder resin. This suppresses the formation of a bond between the precursor of the binder resin and the release agent, and allows the release agent to be transferred to the surface of the molded article.

[0110] Trade names of alkyl pendant polymers include Tesfine (registered trademark) from Resonac Co., Ltd., Ashioresin (registered trademark) from Asio Sangyo Co., Ltd., Piroil (registered trademark) from Lion Specialty Chemicals Co., Ltd., Rezem from Chukyo Yushi Co., Ltd., and Exepar (registered trademark) from Kao Corporation.

[0111] When imparting water repellency to the surface of a molded article, the acrylic polymer may be a (meth)acrylate polymer having a long-chain alkyl group. The long-chain alkyl group may be an alkyl group having 6 to 30 carbon atoms. The long-chain alkyl group may be linear or branched.

[0112] When the acrylic polymer has a reactive functional group, a copolymer of an acrylic monomer having a reactive functional group and an acrylic monomer having a long-chain alkyl group can be used as the acrylic polymer. When an epoxy group is used as the reactive functional group, glycidyl methacrylate (GMA) can be used as the acrylic monomer having the reactive functional group. When a phenolic hydroxyl group is used as the reactive functional group, 4-hydroxyphenyl methacrylate can be used as the acrylic monomer having the reactive functional group.

[0113] Examples of such acrylic polymers include a copolymer of lauryl acrylate (LA) and glycidyl (meth)acrylate, a copolymer of stearyl acrylate (SA) and glycidyl (meth)acrylate, and a copolymer of lauryl acrylate and 4-hydroxyphenyl methacrylate.

[0114] In the entire release layer 20, the ratio of the binder resin 21 to the total of the binder resin 21 and the surface modifier 22 is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 90% by mass or less, and even more preferably 30% by mass or more and 90% by mass or less.

[0115] The release layer 20 may be substantially formed from a binder resin 21 and a surface modifier 22. Furthermore, the release layer 20 may contain additives as needed. Examples of additives include stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, thickeners, lubricants, foaming agents, antifoaming agents, inorganic particles, and organic particles.

[0116] The release film 1 preferably uses PET, a polyester, as the material for the substrate 10 and a curable resin containing acrylic polyol resin as the binder resin 21 of the release layer 20. The acrylic polyol resin does not have the above-mentioned specific functional group.

[0117] Furthermore, when the hydroxyl groups contained in the acrylic polyol resin react with the crosslinking agent, it is believed that the hydroxyl groups derived from the ethylene glycol contained in the PET also react with the crosslinking agent, forming a chemical bond between the binder resin 21 and the surface of the substrate 10. This makes it easier for the release layer 20 to bond firmly to the surface 10a of the substrate 10.

[0118] When the substrate 10 and binder resin 21 are combined as described above, the surface modifier 22 that imparts water repellency to the molded article is preferably an alkyl pendant polymer containing a long-chain alkyl.

[0119] By using a resin or resin precursor with high polarity as the binder resin 21 or the binder resin precursor (described later), and using a compound or resin with lower polarity than the binder resin 21 or the binder resin precursor as the surface modifier, the surface modifier can be concentrated on the surface side of the release layer of the resulting release film.

[0120] [Release film manufacturing method] 2 and 3 are schematic diagrams showing a method for producing a release film. First, as shown in FIG. 2, a mixed liquid containing a precursor 21x of the binder resin 21 and a surface modifier 22 is applied to the surface 10a of the substrate 10 to form a coating film 29.

[0121] The binder resin 21 preferably uses an acrylic polyol resin as the precursor 21x. When an acrylic polyol resin is used as the precursor 21x, the precursor 21x and the surface modifier 22 are highly compatible with each other, so that the mixture is easily mixed homogeneously, and a homogeneous coating film is easily formed.

[0122] For example, when a curable resin containing an acrylic polyol resin as a main component is used as the binder resin 21, a mixture of a precursor 21x (acrylic polyol resin) of the binder resin 21, a crosslinking agent (e.g., melamine resin), and a surface modifier 22 is dissolved in a solvent, and then applied to the substrate 10 by a known application method. Note that the "coating film" is considered to contain a solvent.

[0123] If necessary, a curing agent for the precursor 21x and the crosslinking agent is also mixed into the mixed solution. The curing agent may be an acid catalyst that promotes crosslinking.

[0124] The solvent to be used may be selected so that the precursor 21x and the surface modifier 22 can be uniformly dissolved in consideration of their solubility in the solvent and the solubility in the solvent of the surface modifier 22. Examples of the solvent to be used include polar solvents such as alcohol-based solvents such as ethanol and isopropyl alcohol, ether-based solvents such as diethyl ether and tetrahydrofuran, ketone-based solvents such as acetone and methyl ethyl ketone (MEK), and ester-based solvents such as ethyl acetate, and non-polar solvents such as hydrocarbon-based solvents such as toluene, xylene, n-hexane, n-heptane, cyclohexane, and methylcyclohexane.

[0125] The coating method is not particularly limited, and examples thereof include gravure coating, Mayer bar coating, air knife coating, die coating, blade coating, etc. To form a thin coating film 29, it is preferable to dissolve the composition in a coating solvent and adjust the viscosity before coating.

[0126] Next, as shown in FIG. 3, the coating film 29 is dried to form the release layer 20.

[0127] Drying removes the solvent from the coating film 29. This relatively increases the concentration of the curing agent, accelerating the polymerization reaction of the precursor 21x. As the polymerization reaction progresses, the binder resin 21 bonds with the surface 10a of the substrate 10 and becomes more likely to be present on the substrate 10 side. The surface modifier 22 is relatively pushed toward the surface 20a of the release layer 20, and separation of the binder resin 21 and the surface modifier 22 progresses. As a result, the content of the surface modifier 22 in the resulting release layer 20 gradually decreases from the surface 20a of the release layer 20 toward the substrate 10.

[0128] Prior to the step of forming the coating film shown in FIG. 2, a test may be conducted to determine a suitable combination of the binder resin 21 and the surface modifier 22, and the binder resin 21 and the surface modifier 22 may be selected.

[0129] A simple evaluation can be performed to determine the combination of binder resin 21 and surface modifier 22 using a test piece made of the same material as the material to which the release film is laminated. Specifically, a release film is laminated onto a prepared test piece, the surface modifier is transferred from the release film, and then the test piece is peeled off, and the physical properties of the surface of the test piece to which the release film is laminated (transfer surface) are measured. From the measurement results, it can be determined whether the combination of binder resin 21 and surface modifier 22 used in the release film allows for the desired surface modification.

[0130] For example, if the release film has the function of imparting water repellency to the surface to which it is laminated, a test for measuring the contact angle of the transfer surface can be used as the test for making the above judgment. If the contact angle of the transfer surface is 90° or more, it can be determined that sufficient water repellency can be imparted.

[0131] The release film 1 can be obtained by the above-described manufacturing method.

[0132] [Laminates (laminated films)] 4 and 5 are schematic cross-sectional views showing the laminate (laminated film) of this embodiment. As shown in Fig. 4, the laminated film 100 is in contact with the release layer 20 of the release film 1 described above, and has a resin layer 50 formed on the release layer 20. The resin layer 50 is in contact with the surface 20a of the release layer 20. The laminated film 100 corresponds to the laminate of the present invention. The resin layer 50 corresponds to the molded article of the present invention.

[0133] The resin layer 50 has a specific functional group that reacts with the reactive functional group of the surface modifier 22 to form a covalent bond. Examples of such specific functional groups include at least one selected from the group consisting of an epoxy group, a phenolic hydroxyl group, a cyanate ester group, and an active ester group. The active ester group refers to the same functional group as the active ester group described above in (Binder Resin).

[0134] Specifically, when the surface modifier 22 contained in the release film 1 used has an epoxy group as a reactive functional group, the resin layer 50 has at least one specific functional group selected from the group consisting of a phenolic hydroxyl group, an epoxy group, a glycidyl group, a cyanate ester group, and an active ester group.

[0135] Furthermore, when the surface modifier 22 contained in the release film 1 used has a phenolic hydroxyl group as a reactive functional group, the resin layer 50 has at least one specific functional group selected from the group consisting of an epoxy group and a glycidyl group.

[0136] The resin layer 50 can be formed by casting on the release layer 20. The material for the resin layer 50 is not particularly limited as long as it is a resin having a specific functional group and soluble in a solvent, a liquid resin that can be fluidized without a solvent, or a resin composition containing a liquid monomer that can be cured by radical polymerization or the like after application. Examples of materials for the resin layer 50 include acrylic resin, urethane resin, epoxy resin, vinyl chloride resin, solvent-soluble polyimide resin, and polyester resin. Among these, the material for the resin layer 50 before the curing reaction corresponds to the "precursor for forming the molded body" in this invention.

[0137] The solvent for the resin to be cast is not particularly limited, but examples include alcohol-based solvents such as ethanol and isopropyl alcohol, ether-based solvents such as diethyl ether and tetrahydrofuran, ketone-based solvents such as acetone and methyl ethyl ketone (MEK), and ester-based solvents such as ethyl acetate.

[0138] The material for the resin layer 50 dissolved in the solvent (material solution) is applied to the substrate and then dried, thereby removing the solvent from the resin layer. If the material solution is adjusted to a low viscosity and the resin is cast, a thin film-like resin layer can be easily formed on the release layer. The thickness of the resin layer formed by casting is not particularly limited, but may be 1 to 50 μm.

[0139] The solvent resistance of the resin layer 50 may be improved by crosslinking the resin after the application of the material solution. To crosslink the resin layer 50, it is preferable to add a crosslinking agent to the material solution. Examples of the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, and a metal chelate-based crosslinking agent.

[0140] Next, the resin layer 50 is reacted with the reactive functional group of the surface modifier 22 in the release layer 20. For example, when the reactive functional group is an epoxy group, the epoxy group can be reacted with the resin layer 50 by heating the laminate of the release film 1 and the resin layer 50 at 160°C to 190°C for 15 to 90 minutes.

[0141] 5, the resin layer 50 can be separated from the laminated film 100 to form a resin film. At this time, the surface modifier 22 is transferred from the release layer 20 to the surface 50a of the resin film that was in contact with the release layer 20. This results in a resin film with a modified surface 50a.

[0142] The surface modifier 22 transferred to the resin layer 50 in this manner forms a bond with the surface of the resin layer 50 via the reactive functional group. Therefore, compared to a case where the surface modifier 22 does not have a reactive functional group, it is more easily transferred to the resin layer 50. In addition, the transferred surface modifier 22 is less likely to be removed by rubbing, and the surface modification of the resin layer 50 by the surface modifier 22 is more likely to be stable.

[0143] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0144] For example, in the above embodiment, the resin layer 50 is formed on the release layer 20 of the release film 1, and the formed resin layer 50 is peeled off to transfer the surface modifier 22 to the surface 50a of the resin layer 50, but this is not limited to this. A molded body may be prepared in advance using a resin having a specific functional group, and the release film 1 may be attached to the surface of the molded body to form a laminate. This allows the reactive functional group of the surface modifier 22 to react with the specific functional group on the surface of the molded body, and then the film is peeled off to transfer the surface modifier 22 to the surface of the molded body.

[0145] At this time, heating may be performed as appropriate to promote the reaction between the reactive functional groups of the surface modifier 22 and the specific functional groups on the surface of the molded article.

[0146] 2 and 3, the release layer 20 is formed by the manufacturing method described with reference to Figures 2 and 3, so that the content of the surface modifier 22 gradually decreases from the surface 20a of the release layer 20 toward the substrate 10, but this is not the only possible configuration. Even if the content of the surface modifier 22 in the release layer 20 of the release film is uniform in the thickness direction of the release layer 20, the effects of the present invention can be achieved as long as no covalent bond that impairs the effects of the present invention is formed between the surface modifier 22 present on the surface of the release layer 20 and the binder resin 21. [Example]

[0147] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0148] [Examples 1 to 7, Comparative Examples 1 to 3] (1) Preparation of release film A polyethylene terephthalate (PET) film was used as the substrate. A mixed liquid prepared by mixing the binder resin solution and the surface modifier described below was applied onto a PET film and dried to form a release layer on the surface of the PET film, thereby producing a release film.

[0149] The materials used to prepare the release film are as follows:

[0150] (surface modifier) Surface modifier 1: a copolymer of lauryl acrylate:glycidyl methacrylate = 100:20 (mass ratio). Surface modifier 2: A copolymer of stearyl acrylate:glycidyl methacrylate = 100:20 (mass ratio). Surface modifier 3: a copolymer of lauryl acrylate and 4-hydroxyphenyl methacrylate in a mass ratio of 100:20. Surface modifier 4: Polylauryl acrylate (100% polymer of lauryl acrylate). Surface modifier 5: a copolymer of lauryl acrylate and 4-hydroxybutyl acrylate in a mass ratio of 100:20.

[0151] Surface modifiers 1 to 5 were all initially in the form of butyl acetate solutions with a solid content of 35% by mass, which were diluted with MEK to give solutions with a solid content of 2.5% by mass.

[0152] It was confirmed that the weight-average molecular weight of all of surface modifiers 1 to 5 was approximately 60,000. The glycidyl group (epoxy group) possessed by surface modifiers 1 and 2 and the phenolic hydroxyl group possessed by surface modifier 3 correspond to the reactive functional group in the present invention.

[0153] (binder resin solution) Binder resin precursor: Acrylic polyol (SU-100ADT, Soken Chemical) Crosslinking agent: melamine compound, Cymel 303LF (manufactured by Allnex)

[0154] The binder resin precursor and crosslinker were mixed and diluted with MEK to prepare a binder resin solution with a solid content of 25% by mass. In the binder resin solution, the ratio of binder resin precursor to crosslinker was 7:3 (mass ratio of solids). The binder resin precursor and crosslinker polymerized to produce a binder resin. The resulting binder resin did not have any specific functional groups.

[0155] (mixed liquid) One of the above-mentioned surface modifier solutions was mixed with a binder resin solution and an acid catalyst (a 10% methanol solution of paratoluenesulfonic acid) as a curing agent, and the mixture was diluted with MEK to prepare a mixture used in producing each of the release films of Examples 1 to 7 and Comparative Examples 1 to 3. The solid content of the mixture was 3.0% by mass (Example 1, Comparative Example 3) and 3.1% by mass (Examples 2 to 7, Comparative Examples 1 and 2), respectively.

[0156] The release films of Examples 1 to 7 and Comparative Examples 1 to 3 were produced by changing the type and amount of the surface modifier used.

[0157] (2) Formation of laminated film As an epoxy resin solution, a mixed liquid having the composition shown in Table 1 below was prepared. Difunctional epoxy resin: YL9133 (Mitsubishi Chemical Corporation, molecular weight approximately 400) High molecular weight epoxy resin: YX7891T30 (manufactured by Mitsubishi Chemical Corporation, molecular weight approximately 30,000) Crosslinking agent: Polyarylate with phenolic hydroxyl groups at the terminals and active ester groups in the main chain, Unifiner V-575 (Unitika Ltd.) Curing accelerator: DMAP (4-Dimethylaminopyridine)

[0158] The molecular weights of the bifunctional epoxy resin and the high molecular weight epoxy resin were determined from the graphs in the manufacturer's catalog. https: / / www.m-chemical.co.jp / products / departments / mcc / cmd / expo / mcc_sasma2022.pdf

[0159] [Table 1]

[0160] For each release film of the Examples and Comparative Examples, the above epoxy resin solution was applied to the release layer using an applicator, and then dried at 90°C for 5 minutes to obtain a coating film. The thickness of the obtained coating film was 15 µm.

[0161] The resulting coating film was overlaid with the corona-treated surface of a PET film (E5100, manufactured by Toyobo Co., Ltd.), and roll-laminated at 70° C. In the following description, the PET film used here will be referred to as the "second film" to distinguish it from the PET film contained in the release film.

[0162] After aging overnight, the epoxy resin layer was cured by heating at 130°C for 30 minutes and then at 180°C for 30 minutes to obtain a laminate.

[0163] The laminated portion of the epoxy resin layer and the second film corresponds to the molded article of the present invention. The epoxy resin layer contains an epoxy group, which is a specific functional group. That is, the molded article (epoxy resin layer + second film) used in this example has a specific functional group on its surface.

[0164] In the obtained laminate, the epoxy resin layer of the molded article was in contact with the release layer of each release film.

[0165] (Evaluation 1: Peel force measurement) The laminated film was cut into a 25 mm wide test piece. The second film of the test piece was fixed, and the release film was gripped and peeled off to measure the peel force (gf / 25 mm). The peel speed was 300 mm / min, and the peel angle was 180°. 1000 gf = 1 kgf = 9.80665 N.

[0166] (Evaluation 2: Contact angle measurement) (1) The water contact angle was measured for the release layer of each release film of the Examples and Comparative Examples, and (2) the surface of the epoxy resin film (resin film) from which the release film was peeled after measuring the release force.

[0167] The test was performed using a fully automatic contact angle meter (DMo-701, manufactured by Kyowa Interface Science Co., Ltd.). 3 μl of pure water was dropped onto the surface 50a, and the contact angle was measured after 5 seconds. The test was performed three times, and the arithmetic average of the measured values ​​was used as the contact angle.

[0168] For (2), the epoxy resin solution was applied to a PET film, dried at 90°C for 5 minutes, and the resulting coating was heated at 130°C for 30 minutes and then at 180°C for 30 minutes to obtain an epoxy resin layer. The water contact angle of the resulting epoxy resin layer was 70°.

[0169] (Evaluation 3: Detection of reactive functional groups) Twenty sheets of 210 mm x 297 mm (A4 size according to A-size standards) were made from the prepared release film.

[0170] 20 mL of chloroform was placed in a stainless steel square tray having a larger planar area than the prepared sheet, and the sheet was immersed in the chloroform with the release layer facing upward.

[0171] The tray was tilted left or right 20 times, and the sheet was then removed from the chloroform. The sheet was held on the tray and the chloroform was collected for 10 seconds. The chloroform in the tray was then collected.

[0172] After the same procedure was performed on 20 sheets, the entire amount of recovered chloroform was removed under reduced pressure using an evaporator, and the sheet was further dried in a vacuum to obtain a solid content (extract). 1 Measurement was carried out by 1 H-NMR (solvent: deuterated chloroform) to detect reactive functional groups.

[0173] The evaluation results are shown in Table 2. In the "Surface Modifier" column of Table 2, the numerical values ​​listed in the "Type" column correspond to the numbers of the above-mentioned surface modifiers 1 to 5. Furthermore, the "Amount" refers to the amount of surface modifier per 100 parts by mass of binder resin.

[0174] [Table 2]

[0175] As a result of the evaluation, each of the release films of Examples 1 to 7 could be peeled from the laminate film. Furthermore, the water contact angle of the surface of the epoxy film obtained by peeling the release film was larger than the reference value (70°), confirming that water repellency was imparted. In the release layer of these release films, the presence of reactive functional groups was confirmed under the conditions of Evaluation 3.

[0176] In contrast, the release films of Comparative Examples 1 and 3 were damaged in Evaluation 1, and could not be peeled off from the laminated film.

[0177] Furthermore, in the release film of Comparative Example 2, the release film was able to be peeled off in Evaluation 1, but the water contact angle on the surface of the obtained epoxy film was no different from the reference value, and water repellency was not imparted.

[0178] The above results confirmed the usefulness of the present invention. [Explanation of symbols]

[0179] 1...Release film, 10...Substrate, 20...Release layer, 21...Binder resin, 22...Surface modifier, 29...Coating film, 50...Resin layer (molded body), 100...Laminated film (laminate)

Claims

1. A substrate; a release layer formed on one surface of the substrate, the release layer includes a binder resin and a surface modifier having a reactive functional group, the reactive functional group is at least one selected from the group consisting of an epoxy group and a phenolic hydroxyl group, The binder resin does not have a specific functional group that forms a covalent bond with the reactive functional group.

2. The release film according to claim 1 , wherein the binder resin comprises a curable resin of an acrylic polyol resin and a crosslinking agent.

3. 3. The release film according to claim 1, wherein the reactive functional group is an epoxy group.

4. 3. The release film according to claim 1, wherein the content of the surface modifier in the release layer is lower on the substrate side than on the surface side of the release layer.

5. The release film according to claim 1 or 2; a molded body in contact with the release layer, The molded body or a precursor for forming the molded body is a laminate having the specific functional group.

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