Curable resin composition, elastomer and sheet

Abstract

A curable resin composition comprising a copolymer (X) and a macromonomer having a functional group polymerizable with a (meth)acryloyl group at at least one terminal, wherein the copolymer (X) comprises: a main chain comprising a structural unit derived from an alkyl (meth)acrylate monomer (A) and a structural unit derived from a hydroxyalkyl (meth)acrylate monomer (B); and a side chain bonded to the structural unit (B) and comprising a structural unit derived from an isocyanate monomer (C) having a (meth)acryloyl group.

Description

Technical Field

[0001] The present invention relates to a curable resin composition, an elastomer, a flexible sheet, a stretchable sheet, and other sheet materials. Specifically, it relates to a sheet material that can be suitably used as a protective film for flexible printed circuits such as flexible printed circuit boards, circuit boards, and wiring boards, and a curable resin composition and a (meth)acrylic elastomer used in the preparation of the sheet material. Background Art

[0002] In recent years, the demand for sheets for electronic components has increased. For example, with the lightweight, miniaturization and high density of electronic products, the attention to so-called flexible printed circuits (hereinafter sometimes referred to as "FPC"), such as flexible printed circuit boards or flexible printed wiring boards, has also increased. FPC can be formed as follows: an insulating film is used as a base film (also called a substrate), a metal foil is attached via an adhesive layer, or a pattern formed by conductive ink or a film is formed. In such an FPC, a flexible resin sheet made of various materials is used as a base film (for example, see Patent Document 1).

[0003] In addition, resin sheets can be used for various purposes such as protecting electronic component substrates, and have been developed to adapt to various uses, such as adhesive tapes, dielectric materials, etc. (for example, see Patent Documents 2 and 3). In addition, resin films for FPC are also being developed.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-145325

[0007] Patent Document 2: Japanese Patent Application Publication No. 2014-105325

[0008] Patent Document 3: Japanese Patent Application Publication No. 2017-132905 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In order to make the flexible sheet fully exert its elasticity, the raw material is required to be soft, and the development of materials showing low Young's modulus has been carried out. However, resin films with excellent softness (low Young's modulus) are usually highly viscous and often show properties such as easy adhesion to other components. As mentioned above, materials with high viscous properties have poor operability, for example, from the perspective of transportability in devices such as screen printing devices, improvements are needed.

[0011] In recent years, there has been an increasing demand for thinner flexible sheets. However, some conventional non-viscous elastomers cannot be made into films by coating. For example, it is difficult to produce an elastomer with a film thickness of less than 0.3 mm.

[0012] In order to solve the above-mentioned problems, an object of the present invention is to provide a curable resin composition which can be applied by coating and can produce an elastomer having low tackiness, and an elastomer and a sheet using the same.

[0013] Means for solving problems

[0014] <1> A curable resin composition comprising a copolymer (X) and a macromonomer having a functional group polymerizable with a (meth)acryloyl group at at least one terminal, wherein the copolymer (X) comprises:

[0015] a main chain including a structural unit derived from an alkyl (meth)acrylate monomer (A) and a structural unit derived from a hydroxyalkyl (meth)acrylate monomer (B); and

[0016] A side chain that is bonded to the structural unit (B) and includes a structural unit derived from an isocyanate-based monomer (C) having a (meth)acryloyl group.

[0017] <2> The curable resin composition according to <1> above, wherein the alkyl (meth)acrylate monomer (A) is represented by the following formula (1).

[0018] [Chemical formula 1]

[0019]

[0020] (Where R 1 Represents a hydrogen atom or a methyl group; R 2 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, which may have a halogen atom or an ether bond, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms.

[0021] <3> The curable resin composition according to <1> or <2>, wherein the hydroxyalkyl (meth)acrylate monomer (B) is represented by the following formula (2).

[0022] [Chemical formula 2]

[0023]

[0024] (Where R 1 represents a hydrogen atom or a methyl group; Z represents O, NH, or S; X 1represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms, which may have a halogen atom. a represents an integer greater than 1.)

[0025] <4> The curable resin composition according to any one of <1> to <3>, wherein the isocyanate monomer (C) is a compound represented by the following formula (3-1).

[0026] [Chemical formula 3]

[0027]

[0028] (Where R 1 represents a hydrogen atom or a methyl group; X 2 represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or a linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms which may have a hydroxyl group.

[0029] <5> The curable resin composition according to any one of <1> to <4>, wherein the macromonomer has a (meth)acryloyl group as the functional group.

[0030] <6> The curable resin composition according to any one of <1> to <5>, wherein the content of the macromonomer is 1 to 50% by mass based on the total amount of the copolymer (X) and the macromonomer.

[0031] <7> The curable resin composition according to any one of <1> to <6>, further comprising a surfactant.

[0032] <8> The curable resin composition according to any one of <1> to <7>, further comprising a polymerization initiator.

[0033] <9> The curable resin composition according to any one of <1> to <8>, further comprising a solvent.

[0034] <10> An elastomer obtained by reacting the curable resin composition according to any one of <1> to <9>.

[0035] <11> An elastomer represented by the following formula (5).

[0036] [Chemical formula 4]

[0037]

[0038] (Where R 1 Represents a hydrogen atom or a methyl group; R 2represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, which may have a halogen atom or an ether bond, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms; Z represents O, NH, or S; X 1 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms, which may have a halogen atom; X 2 represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or a linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms which may have a hydroxyl group; M 1 Indicates the structural unit derived from the macromolecular monomer; l 1 、m 1 and O 1 represents the molar ratio of each structural unit. )

[0039] <12> A sheet comprising the elastomer according to <10> or <11>.

[0040] Effects of the Invention

[0041] According to the present invention, there are provided a curable resin composition which can be applied by coating and can produce an elastomer having low tackiness, and an elastomer and a sheet using the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] [ Figure 1 ] is a graph used to illustrate hysteresis loss and residual deformation. DETAILED DESCRIPTION

[0043] 《Curable resin composition》

[0044] The curable resin composition of the present embodiment comprises a copolymer (X) and a macromonomer having a functional group polymerizable with a (meth)acryloyl group at at least one terminal (hereinafter, sometimes simply referred to as a “macromonomer”), wherein the copolymer (X) comprises a main chain comprising a structural unit derived from an alkyl (meth)acrylate monomer (A) [hereinafter, sometimes simply referred to as “monomer (A)”] and a structural unit derived from a hydroxyalkyl (meth)acrylate monomer (B) [hereinafter, sometimes simply referred to as “monomer (B)”] (hereinafter, sometimes simply referred to as “structural unit (B)”)”; and a side chain comprising a structural unit derived from an isocyanate monomer (C) [hereinafter, sometimes simply referred to as “monomer (C)”] having a (meth)acryloyl group (hereinafter, sometimes simply referred to as “structural unit (C)”)”.

[0045] It should be noted that throughout the present specification, "alkyl (meth)acrylate" means "alkyl acrylate" or "alkyl methacrylate", "hydroxyalkyl (meth)acrylate" means "hydroxyalkyl acrylate" or "hydroxyalkyl methacrylate", and "(meth)acryloyl" means "acryloyl" or "methacryloyl". In addition, unless otherwise specified, the term "alkyl" includes alkyl groups of linear, branched, and alicyclic structures.

[0046] The curable resin composition of the present embodiment is a curable resin composition comprising at least a copolymer (X) and a macromonomer, and comprises a surfactant, a polymerization initiator, a solvent, etc. as required. In addition, for the curable resin composition of the present embodiment, by reacting the copolymer (X) with the macromonomer (preferably a photocuring reaction), a cross-linked structure, etc., is given, so that a (meth) acrylic elastomer with low tackiness can be synthesized. Here, the so-called "elastomer formed by reacting the curable resin composition" refers to an elastomer obtained by the polymerization reaction of the copolymer (X) and the macromonomer. It should be noted that, below, the copolymer (X) is distinguished from the elastomer of the present embodiment for description, but these descriptions do not deny that the copolymer (X) has the property of being an elastomer (elastomer).

[0047] In addition, the copolymer (X) has excellent solubility in solvents. Therefore, the curable resin composition of the present embodiment can be applied by coating, and by curing the coating film formed by coating, a sheet (elastomer) having low tack and, for example, a film thickness of less than 0.3 mm can be produced.

[0048] <Copolymer (X)>

[0049] Copolymer (X) is a copolymer in which a side chain containing structural unit (C) is bonded to a main chain containing structural unit (A) and structural unit (B). The side chain containing structural unit (C) is bonded to structural unit (B). Copolymer (X) can be synthesized, for example, by the following method.

[0050] First, monomer (A) and monomer (B) are polymerized using a polymerization initiator as needed (for example, bulk polymerization by ultraviolet irradiation) to synthesize a first polymer composed of structural units (A) and (B). Next, the first polymer is dissolved in a solvent to prepare a solution, and a monomer (C) is added to the solution (using a catalyst as needed), thereby synthesizing a copolymer (X) in which the structural unit (C) is bonded to the structural unit (B) of the first polymer.

[0051] In addition, the copolymer (X) is a copolymer in which the structural unit (C) functions as a photo-crosslinking site.

[0052] <(Meth)acrylic acid alkyl ester monomer (A)>

[0053] In the present embodiment, the "alkyl (meth)acrylate monomer (A)" is a monomer having one (meth)acryloyl group, and is distinguished from the monomer (B) and the monomer (C) in the present embodiment described later.

[0054] As the monomer (A) in the present embodiment, for example, a compound represented by the following formula (1) can be used.

[0055] [Chemical formula 5]

[0056]

[0057] (Where R 1 Represents a hydrogen atom or a methyl group; R 2 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, which may have a halogen atom or an ether bond, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms.

[0058] In the (meth)acrylic acid alkyl ester monomer represented by formula (1), R 1 is a hydrogen atom or a methyl group. 1 Among them, a hydrogen atom is preferred from the viewpoint of easiness of polymerization and obtaining a (meth)acrylic elastomer having a low Young's modulus.

[0059] In the compound represented by formula (1), R 2 It is a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may have a halogen atom or an ether bond, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms which may have a hydroxyl group.

[0060] Examples of the linear, branched or cyclic alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, cyclohexyl and n-octyl groups, but the present embodiment is not limited to these examples.

[0061] As the halogen atom contained in the alkyl group, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. can be mentioned. The number of halogen atoms contained in the alkyl group varies depending on the number of carbon atoms of the alkyl group, etc., and therefore cannot be determined in general, so it is preferably appropriately adjusted within the range that does not hinder the purpose of the present embodiment.

[0062] Examples of the linear, branched or cyclic alkyl group having 1 to 10 carbon atoms and having a halogen atom include trifluoromethyl, trifluoroethyl, trifluoro-n-propyl, trifluoroisopropyl, trifluoro-n-butyl, trifluoroisobutyl and trifluoro-t-butyl, but the present embodiment is not limited to these examples.

[0063] As the linear, branched or cyclic alkyl group having 1 to 10 carbon atoms and having an ether bond, there can be mentioned, for example, linear alkyl groups such as methoxyethyl acrylate, alkyl groups having cyclic ethers such as tetrahydrofuran, dioxolane, tetrahydropyran, and dioxane, etc. As the alkyl group having a cyclic ether, there can be mentioned the following groups, but the present embodiment is not limited to these examples.

[0064] [Chemical formula 6]

[0065]

[0066] Examples of the linear, branched or cyclic alkoxyalkyl groups having 2 to 12 carbon atoms include alkoxyalkyl groups having 1 to 6 carbon atoms and alkyl groups having 1 to 6 carbon atoms, such as methoxyethyl, ethoxyethyl and methoxybutyl, but the present embodiment is not limited to these examples.

[0067] As R 2 From the viewpoint of low Young's modulus and high solubility in a solvent, a methyl group, an ethyl group, a cyclohexyl group, tetrahydrofuran or dioxolane is preferred, and a methyl group and an ethyl group are more preferred.

[0068] Examples of the (meth)acrylic acid alkyl ester monomer represented by formula (1) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, methylpentyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, and cyclohexyl (meth)acrylate. In formula (1), R 1 is a hydrogen atom or a methyl group, R 2 is an alkyl (meth)acrylate monomer having an alkyl group with 1 to 10 carbon atoms; 2,2,2-trifluoroethyl acrylate, wherein R 1 is a hydrogen atom or a methyl group, R 2 is an alkyl (meth)acrylate monomer having an alkyl group with 1 to 10 carbon atoms and a halogen atom; methyl acrylate (2-methyl-2-ethyl-1,3-dioxolan-4-yl) ester, tetrahydrofurfuryl acrylate. In formula (1), R 1 is a hydrogen atom or a methyl group, R 2is an alkyl (meth)acrylate monomer having an alkyl group with 1 to 10 carbon atoms and which may have an ether bond; methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate, phenoxyethyl acrylate. In formula (1), R 1 is a hydrogen atom or a methyl group, R 2 An alkyl (meth)acrylate monomer having an alkoxyalkyl group having 2 to 12 carbon atoms.

[0069] Among these, the (meth)acrylic acid alkyl ester monomer in the present embodiment is preferably ethyl (meth)acrylate, cyclohexyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, and tetrahydrofurfuryl acrylate, and more preferably methyl acrylate and ethyl acrylate.

[0070] These (meth)acrylate monomers (A) may be used alone or in combination of two or more.

[0071] (Hydroxyalkyl (meth)acrylate monomer (B))

[0072] In the present embodiment, the "hydroxyalkyl (meth)acrylate monomer (B)" is a monomer having one (meth)acryloyl group and at least one hydroxyl group.

[0073] As the monomer (B) in the present embodiment, for example, a compound represented by the following formula (2) can be used.

[0074] [Chemical formula 7]

[0075] (Where R 1 represents a hydrogen atom or a methyl group; Z represents O, NH, or S; X 1 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms, which may have a halogen atom. a represents an integer greater than 1.)

[0076] In the hydroxyalkyl (meth)acrylate monomer represented by formula (2), R 1 is a hydrogen atom or a methyl group. 1 Among them, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred from the viewpoint of low Young's modulus and high solubility in a solvent.

[0077] In the compound represented by formula (2), Z represents -O-, -NH-, or -S-. Among Z, -O- is preferred from the viewpoint of high solubility in a solvent.

[0078] In the compound represented by formula (2), X1 is a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms, which may have a halogen atom. 1 It has at least one hydroxyl group.

[0079] a represented by formula (2) is an integer of 1 or more and is not particularly limited, but is preferably 1 to 3, and preferably 1 or 2, from the viewpoint of low Young's modulus and high solubility in a solvent.

[0080] About X 1 In formula (1), a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms; a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms and having a halogen atom; and a linear, branched or cyclic alkoxyalkyl group having 1 to 10 carbon atoms, including the following: 2 The same groups as those exemplified in the above. Examples of the aryl group include phenyl, biphenyl, naphthyl, anthracenyl, and the like. In addition, as X having one hydroxyl group 1 , for example, the following linear alkyl groups, cyclic alkyl groups or aryl groups can be mentioned.

[0081] [Chemical formula 8]

[0082]

[0083] As the (meth) hydroxyalkyl acrylate monomer represented by formula (2), for example, there is no particular limitation, but from the viewpoint of improving the fracture stress, the following compounds can be cited. In addition to the following compounds, glycerol monomethacrylate having two or more hydroxyl groups can also be used. These (meth) hydroxyalkyl acrylate monomers (B) can be used alone or in combination of two or more.

[0084] [Chemical formula 9]

[0085]

[0086] (Isocyanate monomer (C) having a (meth)acryloyl group)

[0087] In the present embodiment, the "isocyanate-based monomer (C) having a (meth)acryloyl group" is an isocyanate-based monomer having one (meth)acryloyl group.

[0088] As the monomer (C) in the present embodiment, for example, a compound represented by the following formula (3-1) can be used.

[0089] [Chemical formula 10]

[0090]

[0091] (Where R 1 represents a hydrogen atom or a methyl group; X 2 represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or a linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms which may have a hydroxyl group.

[0092] In the monomer (C) represented by formula (3-1), R 1 is a hydrogen atom or a methyl group. 1 Among them, a hydrogen atom is preferred from the viewpoint of improving reactivity.

[0093] In the monomer (C) represented by formula (3-1), X 2 The group represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or a linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms which may have a hydroxyl group.

[0094] Examples of the linear, branched or cyclic alkylene group having 1 to 10 carbon atoms include methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, tert-butylene, sec-butylene, n-pentylene, isopentylene, n-hexylene, isohexylene, cyclohexylene and n-octylene, but the present embodiment is not limited to the above examples.

[0095] Examples of the linear, branched or cyclic alkylene group having 1 to 10 carbon atoms and having a hydroxyl group include hydroxymethylene, hydroxyethylene, hydroxy-n-propylene, hydroxyisopropylene, hydroxy-n-butylene, hydroxyisobutylene and hydroxy-t-butylene, but the present embodiment is not limited to the above examples.

[0096] As the halogen atom contained in the alkylene group, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. can be mentioned. The number of halogen atoms contained in the alkyl group varies depending on the number of carbon atoms of the alkyl group, etc., and therefore cannot be determined uniformly, so it is preferably appropriately adjusted within the range that does not hinder the purpose of the present embodiment.

[0097] Examples of the linear, branched or cyclic alkylene group having 1 to 10 carbon atoms and having a halogen atom include trifluoromethylene, trifluoroethylene, trifluoro-n-propylene, trifluoroisopropylene, trifluoro-n-butylene, trifluoroisobutylene and trifluoro-t-butylene, but the present embodiment is not limited to the above examples.

[0098] Examples of the linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms include alkoxyalkylene groups having 1 to 6 carbon atoms and alkylene groups having 1 to 6 carbon atoms, such as methoxyethylene, ethoxyethylene and methoxybutylene. However, the present embodiment is not limited to the above examples.

[0099] Examples of the linear, branched or cyclic alkoxyalkylene groups having 2 to 12 carbon atoms and having a hydroxy group include hydroxymethoxyethylene, hydroxyethoxyethylene, hydroxymethoxybutylene and other hydroxyalkylene groups having 1 to 6 carbon atoms and alkoxyalkylene groups having 1 to 6 carbon atoms, but the present embodiment is not limited to the above examples.

[0100] The monomer (C) represented by the formula (3-1) is not particularly limited, but from the viewpoint of ease of manufacture and availability, the following compounds (1) to (3) can be cited, and the following compound (4) can be cited as a monomer (C) not represented by the formula (3-1). The monomers (C) can be used alone or in combination of two or more.

[0101] [Chemical formula 11]

[0102]

[0103] (Other monomers)

[0104] The curable resin composition may include monomer components other than the monomer components in the present embodiment according to the desired characteristics. As other monomers, for example, monomers containing carboxyl groups, carboxylic acid alkyl ester monomers other than the (meth) alkyl acrylate monomer (A) represented by formula (1), monomers containing amide groups, monomers containing aromatic groups, styrene monomers, monomers containing nitrogen atoms, fatty acid vinyl ester monomers, betaine monomers, etc. can be cited, but the present embodiment is not limited to the above examples. These monomers can be used alone or in combination of two or more.

[0105] (Synthesis Method of Copolymer (X))

[0106] The copolymer (X) can be synthesized by, for example, a production method including the following PC steps (1) and (2). The method for synthesizing the copolymer (X) is not limited to the method using the compound represented by the chemical formula shown below.

[0107] PC step (1): a step of polymerizing monomer (A) and monomer (B) to synthesize a first polymer, and further dissolving the polymer in a solvent to obtain a resin solution.

[0108] PC step (2): a step of adding a monomer (C) and a catalyst to the obtained resin solution and heating the mixture to obtain a second polymer (copolymer (X))

[0109] The PC step (1) is a step for synthesizing a main chain by polymerizing the monomer (A) and the monomer (B). In the PC step (1), the first polymer serving as the main chain of the copolymer (X) can be obtained by polymerizing the monomer (A) and the monomer (B).

[0110] [Chemical formula 12]

[0111] PC process (1)

[0112]

[0113] The synthesis method of the first polymer is not particularly limited, and examples thereof include bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and the like. However, the present embodiment is not limited to the above examples. Among these polymerization methods, bulk polymerization and emulsion polymerization are preferred from the viewpoint of high molecular weight, and bulk polymerization is more preferred. When the (meth) acrylic elastomer of the present embodiment is obtained by polymerization using bulk polymerization, it is not necessary to use a dispersant, a solvent, etc. during synthesis, and therefore it is not necessary to remove the dispersant, the solvent, etc. from the system in which the polymer of the present embodiment is synthesized, and the productivity is excellent.

[0114] When the first polymer is obtained by polymerization using a solution polymerization method, a solvent can be used. As the solvent, a non-aqueous organic solvent is preferred. As the non-aqueous organic solvent, hydrocarbon organic solvents such as hexane, heptane, octane, isooctane, decane, toluene, and liquid paraffin can be cited; ether organic solvents such as dimethyl ether, ethyl ether, and tetrahydrofuran; ketone organic solvents such as acetone and methyl ethyl ketone; ester organic solvents such as methyl acetate, ethyl acetate, and butyl acetate; chloride organic solvents such as dichloromethane, chloroform, and carbon tetrachloride; dimethylformamide, diethylformamide, dimethyl sulfoxide, dioxane, etc. These organic solvents can be used alone or in combination of two or more. The amount of the solvent varies depending on the type of the solvent, so it cannot be generally limited, but it is generally preferred to be about 100 to 1000 parts by mass per 100 parts by mass of the monomer component.

[0115] The atmosphere during the polymerization to obtain the first polymer is not particularly limited, and may be air, or may be an inert gas such as nitrogen or argon.

[0116] The temperature for polymerizing the first polymer is not particularly limited, but is usually preferably about 5 to 100° C. The time required to polymerize the monomer components varies depending on the polymerization conditions and cannot be determined without exception. The time is arbitrary, but is usually about 10 minutes to 20 hours.

[0117] The polymerization reaction can be terminated at any time when the amount of the remaining monomer component becomes less than 20% by mass. It should be noted that the amount of the remaining monomer component can be measured, for example, using gel permeation chromatography. At this time, in addition to monomer (A) and monomer (B), the above-mentioned polymerization initiator and the like can also be used. The conditions for the bulk polymerization of the first polymer are not particularly limited, but from the viewpoint of obtaining a product within the above-mentioned preferred molecular weight range and the viewpoint of low hysteresis, the preferred ultraviolet irradiation amount is 10 mW / cm 2 Below, more preferably 1 mW / cm 2 Below, more preferably 0.6 mW / cm 2 From the viewpoint of polymerizability, it is preferably 0.01 mW / cm 2 above.

[0118] In the PC step (1), the first polymer can be dissolved in a solvent to prepare a resin solution. The purpose of preparing the first polymer into a resin solution is mainly to allow the first polymer to be added to the monomer (C) and to form a film of the obtained (meth) acrylic elastomer. There is no particular limitation on the solvent for dissolving the first polymer. For example, benzene solvents, ketone solvents, ester solvents, etc. can be used. Specifically, toluene, cyclopentanone, butyl acetate, carbitol acetate, etc. can be mentioned. The solvent used to dissolve the first polymer in the PC step (1) can be used as a solvent for dissolving the copolymer (X) in the curable resin composition described later.

[0119] Next, the PC step (2) is a step of introducing a monomer (C) into the first polymer (a polymer comprising structural units (A) and structural units (B)) to synthesize a second polymer. The second polymer corresponds to the copolymer (X). In the PC step (2), a catalyst can be used together with the monomer (C). The catalyst is mainly added to allow the first polymer synthesized in the PC step (1) to be added to the monomer (C). In the PC step (2), the monomer (C) is introduced into the first polymer through a condensation reaction between the hydroxyalkyl acryloyl group (derived from the monomer (B)) of the first polymer and the isocyanate group of the monomer (C). The catalyst is not particularly limited as long as it can be used for the condensation reaction between the first polymer and the monomer (C), and for example, a tin catalyst can be used.

[0120] [Chemical formula 13]

[0121] PC process (2)

[0122]

[0123] (Where R 1 Represents a hydrogen atom or a methyl group; R 2represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, which may have a halogen atom or an ether bond, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms; Z represents O, NH, or S; X 1 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms, which may have a halogen atom; X 2 represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or a linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms which may have a hydroxyl group; 1 、m 1 represents the molar ratio of each structural unit. )

[0124] As the copolymer (X), the following polymers can be exemplified.

[0125] [Chemical formula 14]

[0126]

[0127] In the PC step (2), the reaction conditions in the reaction of the first polymer and the monomer (C) are not particularly limited, but from the viewpoint of preventing the monomers (C) from reacting with each other and reacting the monomers (C) with the first polymer, the heating temperature is preferably 40 to 100° C., more preferably 60 to 80° C.; the heating time is preferably 0.5 to 12 hours, more preferably 1 to 6 hours. By setting the heating temperature to 40° C. or more and the heating time to 1 hour or more, the monomer C and the first polymer can be fully reacted. In addition, by setting the heating temperature to 100° C. or less and the heating time to 12 hours or less, the monomers (C) can be prevented from reacting with each other.

[0128] In order to polymerize the monomer components in the present embodiment to synthesize the copolymer (X), a polymerization initiator (photopolymerization initiator, thermal polymerization initiator), a chain transfer agent, etc. can be used. Regarding these, the same ones as those described below can be appropriately selected and used.

[0129] The content of the structural unit (A) in the copolymer (X) is not particularly limited, but is preferably 30 to 99% by mass, more preferably 60 to 99% by mass, and particularly preferably 80 to 99% by mass, relative to the total amount of the copolymer (X), from the viewpoint of low Young's modulus and high solubility in a solvent.

[0130] The content of the structural unit (B) in the copolymer (X) is not particularly limited, but from the viewpoint of the solvent resistance and high solubility in solvents of the obtained elastomer, it is preferably 0.05 to 10 mol %, more preferably 0.1 to 5 mol %, and particularly preferably 0.25 to 2.5 mol % relative to the total amount of the structural unit (A).

[0131] The content of the structural unit (C) in the copolymer (X) is not particularly limited, but from the viewpoint of the solvent resistance of the obtained elastomer, it is preferably 0.05 to 10 mol %, more preferably 0.1 to 5 mol %, and particularly preferably 0.25 to 2.5 mol % relative to the total amount of the structural unit (A).

[0132] The weight average molecular weight (Mw) of copolymer (X) is preferably 700,000 or more and 3,000,000 or less. Specifically, from the viewpoint of film-forming property and mechanical properties (low Young's modulus, low hysteresis), it is preferably 700,000 or more, and more preferably 1,000,000 or more. In addition, from the viewpoint of solubility in solvent, it is preferably 3,000,000 or less. The weight average molecular weight of (meth) acrylic elastomer can be measured by gel permeation chromatography [TOSOH (strain), product number: HLC-8320GPC, column: TOSOH (strain), product number: TSKgel GMHH-R, solvent: tetrahydrofuran, flow rate: 0.6mL / min], converted to polystyrene.

[0133] The glass transition temperature of the polymer of the present embodiment is not particularly limited, but is preferably 50° C. or lower, more preferably 20° C. or lower, and particularly preferably 0° C. or lower from the viewpoint of low Young's modulus.

[0134] <Macromere>

[0135] The curable resin composition of the present embodiment contains a macromonomer. The macromonomer functions as a crosslinking agent for the copolymer (X), and the elastomer of the present embodiment can be obtained by reacting the curable resin composition.

[0136] Here, the so-called "macromer" is a molecule that functions as a monomer molecule, that is, a structural unit that can serve as a basic structure of a polymer, and is a polymer having a polymerizable group. The macromonomer in this embodiment has a functional group that can polymerize with a (meth)acryloyl group at at least one terminal.

[0137] The "functional group polymerizable with a (meth)acryloyl group" possessed by the macromonomer in the present embodiment is not particularly limited, and examples thereof include a (meth)acryloyl group, a nitrogen-containing group having a carbon-carbon double bond, and an aromatic group having a carbon-carbon double bond.

[0138] Specific examples of the "functional group polymerizable with a (meth)acryloyl group" include (meth)acryloyl groups such as methylenebisacrylamide and methylenebismethacrylamide, wherein the alkylene group has 1 to 4 carbon atoms; ethylene di(meth)acrylate, ethylene glycol di(meth)acrylate ("EGDMA"), diethylene glycol di(meth)acrylate ("DEGDMA"), propylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and the like; (Meth)acryloyl groups such as acrylate, 1,9-nonanediol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and nonaethylene glycol di(meth)acrylate; nitrogen-containing groups having carbon-carbon double bonds such as diallylamine and triallylamine; aromatic groups having carbon-carbon double bonds such as divinylbenzene and diallylbenzene, etc.

[0139] The number average molecular weight of the macromonomer is not particularly limited, but from the viewpoint of low tack, it is preferably 1000 or more, more preferably 2500 or more, and particularly preferably 5000 or more. The number average molecular weight of the macromonomer can be measured in terms of polystyrene using gel permeation chromatography [manufactured by TOSOH Corporation, product number: HLC-8320GPC, column: manufactured by TOSOH Corporation, product number: SuperH2500, solvent: tetrahydrofuran, flow rate: 0.6 mL / min].

[0140] The macromonomer in this embodiment is not particularly limited, but from the viewpoint of low tack, preferably a macromonomer having a (meth)acryloyl group as a functional group, specifically, a polystyrene macromonomer having a (meth)acryloyl group at least at a terminal, preferably at a single terminal; a polyacrylate macromonomer having a (meth)acryloyl group as a crosslinking group at least at a terminal, preferably at both terminals, etc. As these macromonomers, macromonomers available as commercial products can be appropriately selected, for example, macromonomers manufactured by Toagosei Chemical Co., Ltd. (for example, product name: AS-6 (polystyrene macromonomer), product name: AA-6 (polymethacrylate macromonomer)) and the like can be mentioned.

[0141] The content of the macromonomer in the curable resin composition is not particularly limited, but from the viewpoint of achieving a balance between low tack and deformation suppression, it is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 37% by mass, relative to the total amount of the copolymer (X) and the macromonomer.

[0142] <Solvent>

[0143] The curable resin composition may include a solvent. As described above, the copolymer (X) has excellent solubility in a solvent. The solvent that can dissolve the polymer of the present embodiment is not particularly limited, and examples thereof include benzene-based solvents (e.g., toluene, xylene, etc.), ketone-based solvents (e.g., cyclopentanone, methyl ethyl ketone, acetone, cyclohexanone, etc.), ester-based solvents (e.g., ethyl acetate, hexyl acetate, butyl acetate, carbitol acetate, etc.), etc. As the solvent used in the curable resin composition, from the viewpoint of suppressing the coloring of the obtained elastomer (sheet), preferably a benzene-based solvent, for example, more preferably toluene. The copolymer (X) has excellent solubility in these solvents, and therefore, can produce a sheet (thin film (e.g., less than 0.3 mm)) having a thickness below a certain value, etc., with a high degree of freedom in terms of film thickness and excellent film formation.

[0144] The content of the solvent in the curable resin composition is not particularly limited, but is preferably 50 to 99% by mass, more preferably 80 to 95% by mass, and particularly preferably 85 to 90% by mass, relative to the total amount of the curable resin composition from the viewpoint of adjusting the film thickness.

[0145] <Surfactant>

[0146] The curable resin composition may contain a surfactant. If the curable resin composition contains a surfactant, a thin film or a membrane having less surface irregularities can be formed.

[0147] The content of the surfactant in the curable resin composition is not particularly limited, but from the viewpoint of suppressing the generation of unevenness on the coating film surface during coating, it is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass, and particularly preferably 0.1 to 0.3% by mass relative to the total amount of the curable resin composition.

[0148] As the above-mentioned surfactant, for example, dimethylsiloxane surfactants and fluorine-based surfactants can be mentioned, and dimethylsiloxane surfactants are preferred. In addition, as the surfactant, a surfactant having a crosslinkable functional group such as polyether-modified dimethylsiloxane containing an acryloyl group is preferred. As the crosslinkable functional group, (meth)acryloyl and allyl groups can be mentioned.

[0149] As the surfactant, commercially available products such as BYK-UV3500, BYK-UV3505, BYK-UV3510, BYK-UV3535, BYK-UV3570, BYK-UV3575, and BYK-UV3576 manufactured by BYK Additives & Instruments can be used. Among them, BYK-UV3500 is preferred.

[0150] <Polymerization initiator>

[0151] The curable resin composition may contain a polymerization initiator for the reaction between the copolymer (X) and the macromonomer. Examples of the polymerization initiator include photopolymerization initiators and thermal polymerization initiators. Among these polymerization initiators, photopolymerization initiators are preferred from the viewpoint of not leaving any thermal history in the (meth)acrylic elastomer.

[0152] -Photopolymerization initiator-

[0153] Photopolymerization initiators are compounds that are activated by various active light rays, such as ultraviolet rays, to initiate polymerization. Examples of photopolymerization initiators include free radical photopolymerization initiators, cationic photopolymerization initiators, and anionic photopolymerization initiators. These photopolymerization initiators may be used alone or in combination of two or more. For example, two or more free radical photopolymerization initiators may be used in combination.

[0154] Examples of the radical photopolymerization initiator include the following compounds.

[0155] Acylphosphine oxide compounds: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (product name: Irgacure TPO, manufactured by BASF), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (product name: Irgacure 819, manufactured by BASF; product name: Irgacure 819DW, manufactured by BASF)

[0156] α-Hydroxyketone compounds: 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure 184, manufactured by BASF), 2-hydroxy-2-methyl-1-phenyl-propane-1-one (product name: Irgacure 1173, manufactured by BASF), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one (Irgacure 2959, manufactured by BASF), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1-one (product name: Irgacure 127, manufactured by BASF)

[0157] Intramolecular hydrogen abstraction compound: Methyl benzoylformate (product name: Irgacure MBF, manufactured by BASF)

[0158] Titanocene compound-based compounds: 1-[4-(phenylthio)-2-(o-benzoyloxime)], bis(η5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyltitanium] (product name: Irgacure 784, manufactured by BASF)

[0159] Benzil ketal compound: 2,2-dimethoxy-1,2-diphenylethane-1-one (product name: Irgacure 651, manufactured by BASF)

[0160] α-Aminoketone compounds: 2-methyl-4'-methylthio-2-morpholinopropiophenone (product name: Irgacure 907, manufactured by BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (product name: Irgacure 369, manufactured by BASF), 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone (product name: Irgacure 379EG, manufactured by BASF)

[0161] Oxime ester compounds that can be used include 1-[4-(phenylthio)-2-(O-benzoyl oxime)] (product name: Irgacure OXE-01, manufactured by BASF), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyl oxime) (for example, product name: Irgacure OXE-02, manufactured by BASF; product name: Irgacure OXE-03, manufactured by BASF; product name: Irgacure OXE-04, manufactured by BASF; product name: N-1919, manufactured by ADEKA; product name: N-1414, manufactured by ADEKA), and the like.

[0162] As other free radical photopolymerization initiators, there can be mentioned, for example, quinone compounds (for example, 2-ethylanthraquinone, 2-tert-butylanthraquinone); aromatic ketones (for example, benzophenone, benzoin); benzoin ether compounds (for example, benzoin methyl ether, benzoin ethyl ether); acridine compounds (for example, 9-phenylacridine (product name: N-1717, manufactured by ADEKA)); triazine compounds (for example, 2,4-trichloromethyl-(4″-methoxyphenyl)-6-triazine, 2,4-trichloromethyl-(4′-methoxynaphthyl)-6-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, 2,4-trichloromethyl-(4′-methoxyphenyl)-6-triazine, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one), etc.

[0163] Examples of the cationic photopolymerization initiator include the following compounds.

[0164] Ionium salt compounds: diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, 4,4'-di-tert-butyldiphenyliodonium tetrafluoroborate, (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate (product name: Irgacure 250: manufactured by BASF)

[0165] Diazonium salt compounds: 4-diethylaminophenylbenzenediazonium hexafluorophosphate

[0166] Sulfonium salt compounds: diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, triarylsulfonium tetrakis(pentafluorophenyl)borate (product name: Irgacure 290, manufactured by BASF), triarylsulfonium hexafluorophosphate (for example, product name: Irgacure 270, manufactured by BASF; product name: CPI300, manufactured by Sanyo Chemical Industries, Ltd.; product name: CPI400, manufactured by Sanyo Chemical Industries, Ltd.),

[0167] Ferrocenium salt compounds

[0168] Examples of the anionic photopolymerization initiator include 1,5,7-triazabicyclo[4.4.0]dec-5-ene-2-(9-oxoxanthene-2-yl)propanoate.

[0169] In addition, a photosensitizer may be used together with the photopolymerization initiator. As the photosensitizer, for example, 4-dimethylaminobenzoic acid ethyl ester (Darocur EDB: manufactured by BASF) and 4-dimethylaminobenzoic acid-2-ethylhexyl ester (Darocur EHA: manufactured by BASF) as amines, and benzophenones, thioxanthones, ketocoumarins, and anthraquinones (Anthracure UVS-581: manufactured by Kawasaki Chemical Industries) as ketone compounds may be used.

[0170] -Thermal polymerization initiator-

[0171] As the thermal polymerization initiator, for example, dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobisisobutyrate dimethyl, azobisdimethylvaleronitrile and other azo polymerization initiators, benzoyl peroxide, potassium persulfate, ammonium persulfate and other peroxide polymerization initiators can be cited, but the present embodiment is not limited to the above examples. These polymerization initiators can be used alone or in combination of two or more.

[0172] The amount of the polymerization initiator varies depending on the type of the polymerization initiator and the like, and therefore cannot be determined without limitation, but is usually preferably about 0.01 to 20 parts by mass per 100 parts by mass of the copolymer (X).

[0173] (Chain transfer agent)

[0174] For the curable resin composition, when the monomer components in the present embodiment are polymerized, a chain transfer agent can be used in order to adjust the molecular weight of the obtained (meth) acrylic elastomer. As the chain transfer agent, compounds having a thiol group such as lauryl mercaptan, dodecyl mercaptan, thioglycerol, etc. can be cited; inorganic salts such as sodium hypophosphite and sodium bisulfite, organic solvents such as toluene and cyclopentanone, etc., but the present embodiment is not limited to the above examples. These chain transfer agents can be used alone or in combination of two or more. The amount of the chain transfer agent varies depending on the type of the chain transfer agent, etc., and therefore cannot be determined in general, but it is generally preferred that it is about 0.01 to 100 parts by mass per 100 parts by mass of the copolymer (X).

[0175] Elastomer

[0176] As described above, for the curable resin composition of the present embodiment, the elastomer can be synthesized by reacting the copolymer (X) with the macromonomer (preferably by photocuring reaction). Specifically, the elastomer of the present embodiment can be synthesized by reacting the copolymer (X) with the macromonomer so that the macromonomer is bonded to the photocrosslinking site (i.e., structural unit (C)) of the copolymer (X).

[0177] It should be noted that the shape such as width, thickness, and length of the elastic body of the present embodiment is not particularly limited.

[0178] The method for producing the elastomer of the present embodiment is not particularly limited, and the elastomer can be synthesized, for example, by the following PC step (3).

[0179] The PC step (3) is a step of further reacting the copolymer (X) (the above-mentioned second polymer) by light irradiation to thereby prepare a (meth)acrylic elastomer. As shown below, the copolymer (X) has an acryloyl group derived from the monomer (C). In the PC step (3), for example, by irradiating light to a curable resin composition that contains a solvent, a photopolymerization initiator, a surfactant, etc. as needed in addition to the copolymer (X) and the macromonomer, the acryloyl groups of the copolymer (X) and the macromonomer can be bonded to each other, thereby obtaining the elastomer of the present embodiment. The light irradiation conditions in the PC step (3) are not particularly limited, and ultraviolet rays can be used. From the viewpoint of reliably bonding the acryloyl groups of each polymer to each other and the viewpoint of the necessary and sufficient irradiation amount, the cumulative irradiation amount of ultraviolet rays is preferably 600 to 7000 mJ / cm2 , more preferably 2800 to 5600 mJ / cm 2 The ultraviolet radiation dose is preferably 4200 mJ / cm 2 In addition, the atmosphere when the copolymer (X) and the macromonomer are reacted is not particularly limited, and can be any atmosphere of an inert gas such as air, nitrogen, argon, etc., but from the viewpoint of suppressing the reaction hindrance caused by oxygen (especially when the lamination treatment described later is not implemented), an inert gas such as nitrogen, argon, etc. is preferably used.

[0180] [Chemical formula 15]

[0181] PC process (3)

[0182]

[0183] (In formula (5), R 1 , R 2 , Z, X 1 and X 2 Each independently is the same as the above formula (1), (2) and (3-1); M 1 Indicates the structural unit derived from the macromolecular monomer; l 1 、m 1 and O 1 represents the molar ratio of each structural unit. )

[0184] As described above, the copolymer (X) has excellent solubility in a solvent. Therefore, a curable resin composition obtained by dissolving the copolymer (X) and a macromonomer in a solvent can be used, and the composition can be formed into a coating film by coating, etc., and the coating film can be dried and subjected to the above-mentioned photocuring to obtain a sheet-like (or film-like) elastomer.

[0185] When a film is formed by coating, it is possible to achieve a thin film (for example, less than 0.3 mm (300 μm)) while maintaining desired mechanical properties (especially low tack).

[0186] Sheet

[0187] The sheet using the elastic body of the present embodiment is excellent in flexibility, elongation, and stretchability, and therefore can be suitably used as a flexible sheet or a stretchable sheet.

[0188] The thickness of the sheet of the present embodiment is not particularly limited, but from the viewpoint of obtaining a sheet that achieves both low tack and thin film, it is more preferably less than 300 μm, and particularly preferably less than 100 μm. In addition, the sheet of the present embodiment not only achieves a thinness below a specified value, but also has excellent mechanical properties, for example, it can achieve a thinness of about 100 μm while exhibiting low tack.

[0189] The sheet of the present embodiment may contain an appropriate amount of other polymers in order to adjust the viscosity thereof.

[0190] Examples of other polymers include acrylic resins, polyacrylonitrile, poly(meth)acrylamide, polyamide, polyvinyl chloride, polyurethane, polyester, and carboxymethyl cellulose, but the present embodiment is not limited to the above examples. These other polymers may be used alone or in combination of two or more.

[0191] The sheet of this embodiment may contain a neutralizer as needed. As the neutralizer, inorganic alkaline compounds such as sodium hydroxide and potassium hydroxide; organic alkaline compounds such as monoethanolamine, dimethylethanolamine, diethylethanolamine, triethanolamine, morpholine, aminomethylpropanol, aminomethylpropanediol, octylamine, tributylamine, and aniline may be cited, but this embodiment is not limited to the above examples. These neutralizers may be used alone or in combination of two or more.

[0192] In addition, from the viewpoint of low tack, the sheet of the present embodiment preferably has a processed surface to which a surface treatment has been applied. The surface treatment is not particularly limited, and examples thereof include sandblasting (concave-convex processing). Here, the concept of "sandblasting" in the present embodiment includes: using a mold to which a sandblasting process has been applied to mold the film; using the film made using the mold as a release film, and transferring the pattern formed on the release film to the surface of the sheet (so-called lamination). For example, fine particles of sand can be blown into the mold cavity of the mold using air, etc., to make extremely small traces, and the mold is used to transfer to the surface of the sheet. It should be noted that the pattern transferred to the surface of the sheet is affected by surface tension and curing shrinkage, and the surface roughness of the release film is not necessarily transferred as it is.

[0193] From the viewpoint of low tack, the arithmetic mean roughness (Ra) of at least one surface of the sheet of the present embodiment is preferably 50 to 1000, more preferably 50 to 500, and particularly preferably 50 to 300. The arithmetic mean roughness can be measured by the method described in Examples below.

[0194] For example, as an example of lamination processing, the following method can be cited: a release film (for example, "SP-PET 100-O1-BU" manufactured by Mitsui Chemicals Tohcello, Inc.) and a sandblasting film (a film obtained by sand-grinding the above-mentioned release film) are attached to the upper surface of the dried coating film (curable resin composition), and the film is passed through a heated laminating device. Through this operation, the upper surface of the coating film of the curable resin composition is isolated from the oxygen in the air, and can be photocured without nitrogen treatment. For example, when a sandblasting film is used, the concave and convex surface of the sandblasting film is transferred to the coating film, which can improve the non-stickiness of the coating film. It should be noted that in the lamination process, the release film or the sandblasting film can be attached to both sides of the coating film, or only to one side, depending on the desired use.

[0195] Furthermore, by laminating the coating film of the curable resin composition, the influence of reaction inhibition due to oxygen in the atmosphere can be reduced, so that even when curing is performed in the air, for example, the curing efficiency of the coating film of the curable resin composition can be improved.

[0196] The sheet of the present embodiment may contain additives within the range that does not hinder the purpose of the present embodiment. As additives, for example, colorants, antioxidants, ultraviolet absorbers, anti-aging agents, thermal conductive fillers, conductive fillers, etc. can be cited, but the present embodiment is not limited to the above examples.

[0197] The Young's modulus, breaking stress, and strain of the sheet of the present embodiment can be measured, for example, using a tensile tester according to the method described in the examples described later.

[0198] The Young's modulus of the sheet of the present embodiment is preferably about 5.00 MPa or less, more preferably 1.0 MPa or less, and particularly preferably 0.7 MPa or less.

[0199] From the viewpoint of expansion and contraction and elongation, the strain of the sheet of the present embodiment is preferably 200% or more.

[0200] The hysteresis and 100 modulus of the sheet of the present embodiment can be measured by the method described in the examples described below. Specifically, regarding the hysteresis, the "residual strain" and "hysteresis loss" of the sheet can be measured and evaluated as an index.

[0201] From the viewpoint of smoothly following the bending and elongation of the object to be protected, the sheet of this embodiment preferably has a residual strain of 1.3% or less, more preferably 1.15% or less, further preferably 1.05% or less, and particularly preferably 1% or less.

[0202] The sheet material of this embodiment can exhibit low stickiness and thin film with good balance, and therefore can be suitably used for base films of FPCs, protective films of substrates for electronic components, auxiliary materials for assisting the movement of movable parts, telescopic materials that expand and contract following the movement of telescopic components, medical materials, fiber products, health materials, life science materials, or robotic materials, etc.

[0203] Example

[0204] Next, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to the following examples.

[0205] [Example 1]

[0206] <Synthesis of EA-HEA-AOI-AS6>

[0207] (Synthesis of Copolymer (X))

[0208] 340 g of ethyl acrylate (monomer (A)), 3.94 g of 2-hydroxyethyl acrylate (monomer (B)), and 0.42 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, trade name: Irgacure TPO) as a polymerization initiator were mixed to obtain a monomer component containing a polymerization initiator.

[0209] The obtained monomer components were filled into a SUS molding container (length: 43 cm, width: 43 cm, depth: 2 mm), and covered from above with a transparent glass (length: 43 cm, width: 43 cm, thickness: 2 mm). The irradiation dose was 0.58 mw / cm 2 The monomer components were irradiated with ultraviolet rays from above in a manner to carry out bulk polymerization of the monomer components for 2 hours, thereby obtaining a first polymer (polymer of monomers (A) to (B)).

[0210] Next, 8.05 g of the obtained first polymer was dissolved in 72.45 g of toluene to obtain a resin solution. 0.1016 g of the following monomer (C-1) and 0.0149 g of a tin catalyst [Nitto Chemical Industry Co., Ltd., product name: Neostann U-100] were added to the obtained resin solution, and the mixture was stirred at 70° C. for 2 hours to obtain a resin solution containing a copolymer (X).

[0211] [Chemical formula 16]

[0212]

[0213] (Preparation of curable resin composition)

[0214] To 11.40 g of the obtained resin solution (10% by mass solution) (content of copolymer (X): 1.14 g) were added 0.01 g of 2-hydroxy-2-methyl-1-phenyl-propane-1-one [manufactured by Tokyo Chemical Industry Co., Ltd.] as a polymerization initiator, 0.12 g of a polystyrene-based macromonomer (manufactured by Toagosei Chemical Co., Ltd., trade name: AS-6), and 0.01 g of a surfactant (manufactured by BYK Additives & Instruments, trade name: BYK-UV3500) and stirred to prepare a curable resin composition.

[0215] (Formation of sheet-like elastic body)

[0216] Two films were prepared by subjecting sandblasted films (films manufactured by PANAC Co., Ltd. (trade name: SP-PET 100-O1-BU)) subjected to D-type sand grinding by Kaisei Kogyo Co., Ltd. The arithmetic mean roughness (JIS B 0601) of the surface of each sandblasted film was 430 nm.

[0217] The curable resin composition obtained in the above manner is applied onto a sandblasted film (hereinafter, this film is referred to as “back side film”) to form a coating film.

[0218] Thereafter, the coating film was heated at 60°C for 1 hour to remove the solvent, thereby obtaining a film-like coating film. Another sandblasting film (hereinafter referred to as the "surface-side film") was attached to the obtained coating film, and a press treatment was performed using a heated laminator (manufactured by FUJIPLA, used at 135°C). The obtained film-like coating film was irradiated with ultraviolet light at an amount of 67 mW / cm in an air atmosphere. 2 × 7 seconds × 10 passes (cumulative irradiation: 4690 mJ / cm 2 ) under the conditions of curing to obtain an elastic body (sheet) 1 sandwiched by the front side film and the back side film. Hereinafter, in the elastic body (sheet) 1, the surface on the front side film side is referred to as the front surface, and the surface on the back side film side is referred to as the back surface.

[0219] [Example 2]

[0220] <Synthesis of EA-HEA-AOI-AS6>

[0221] In Example 1, an elastomer (sheet) 2 was obtained in the same manner as in Example 1 except that the surfactant (BYK-UV3500) was not used and the amount of polystyrene-based macromonomer (manufactured by Toagosei Chemical Co., Ltd., trade name: AS-6) added was changed to 0.67 g.

[0222] [Example 3]

[0223] <Synthesis of EA-HEA-AOI-AS6>

[0224] An elastomer (sheet) 3 was obtained in the same manner as in Example 1 except that the amount of the polystyrene-based macromonomer (manufactured by Toagosei Chemical Co., Ltd., trade name: AS-6) added was changed to 0.28 g.

[0225] [Example 4]

[0226] <Synthesis of EA-4HBA-MOIEG-AS6>

[0227] (Synthesis of copolymer (X))

[0228] 1200 g of ethyl acrylate (monomer (A)), 8.64 g of 4-hydroxybutyl acrylate (monomer (B)) represented by the following formula B-2, and 1.49 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, trade name: Irgacure TPO) as a polymerization initiator were mixed to obtain a monomer component containing a polymerization initiator.

[0229] [Chemical formula 17]

[0230]

[0231] The obtained monomer component was irradiated with a radiation dose of 0.62 mw / cm 2 The monomer components were bulk polymerized for 2 hours in the same manner as in Example 1, thereby obtaining a first polymer (polymer of monomers (A) to (B)).

[0232] Next, 493 g of the obtained first polymer was dissolved in 2791 g of toluene to obtain a resin solution. 9.71 g of the following monomer (C-2) and 0.99 g of a tin catalyst [Nitto Chemical Industry Co., Ltd., product name: Neostann U-100] were added to the obtained resin solution, and the mixture was stirred at 70° C. for 2 hours to obtain a resin solution containing a copolymer (X).

[0233] [Chemical formula 18]

[0234]

[0235] (Preparation of curable resin composition)

[0236] To 63.28 g of the obtained resin solution (15% by mass solution) (content of copolymer (X): 9.492 g) were added 0.09 g of 2-hydroxy-2-methyl-1-phenyl-propane-1-one [manufactured by Tokyo Chemical Industry] as a polymerization initiator and 1.05 g of a polystyrene-based macromonomer (manufactured by Toagosei Chemical Co., Ltd., trade name: AS-6), and the mixture was stirred to prepare a curable resin composition.

[0237] (Formation of sheet-like elastic body)

[0238] In the same manner as in Example 1, an elastic body (sheet) 4 sandwiched between the front-side film and the back-side film was obtained.

[0239] [Example 5]

[0240] <Synthesis of EA-4HBA-MOIEG-AS6>

[0241] An elastomer (sheet) 5 was obtained in the same manner as in Example 4 except that 0.04 g of a surfactant (manufactured by BYK Additives & Instruments, trade name: BYK-UV3500) was added to 46.62 g of the curable resin composition obtained in Example 4.

[0242] [Comparative Example 1]

[0243] <Synthesis of EA-HEA-AOI>

[0244] In Example 1, an elastic body (sheet) 6 was obtained in the same manner as in Example 1 except that no macromonomer was added, no sandblasting film was attached, and no pressing treatment was performed using a laminator.

[0245] [Comparative Example 2]

[0246] 50.02 g of ethyl acrylate, 1.22 g of diethylene glycol dimethacrylate (DEGDMA) (1 mol % relative to ethyl acrylate), 5.69 g of a polystyrene macromonomer (manufactured by Toagosei Chemical Co., Ltd., trade name: AS-6) (10 mass % relative to the total solid content in the composition)) and 0.0314 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, trade name: Irgacure TPO) as a polymerization initiator were mixed to obtain a curable resin composition containing a polymerization initiator.

[0247] The obtained curable resin composition was injected into a transparent glass molding mold (a 0.3 mm thick silicon spacer, which can form a film with a length of 100 mm, a width of 100 mm, and a thickness of 0.3 mm). Next, the molding mold was placed in a water bath and irradiated with a radiation dose of 0.20 mW / cm 2 The curable resin composition was irradiated with ultraviolet rays for 2 hours to polymerize the monomer components. Thereafter, the molding die was taken out from the water bath, and a film (elastic body 7) formed of the (meth) acrylic elastomer was taken out from the molding die.

[0248] The obtained elastic body 7 was excellent in tackiness, but was not soluble in a solvent and could not be formed into a sheet by coating. Therefore, a sheet having a thickness of less than 0.3 mm could not be formed.

[0249] "evaluate"

[0250] The physical properties of the sheets of Examples and Comparative Examples were measured by the following methods.

[0251] [film thickness]

[0252] The obtained elastomer was subjected to sandblasting by peeling off the front and back films, and the thickness of the sheet was measured using a thickness meter (product name: PG-20, manufactured by Teclock Corporation). The measurement was performed 5 times at any location, and the average value was taken as the thickness of the sheet.

[0253] [Solubility in solvents]

[0254] A solvent was added to the polymers obtained in each example and comparative example (copolymer (X) in the example and comparative example 1, and elastomer 7 in comparative example 2) so that the resin concentration became 10%, and the mixture was placed in a 55°C constant temperature bath overnight and stirred using a rotation and revolution stirrer. Thereafter, whether or not the mixture was uniformly dissolved was visually confirmed, and the solubility of the polymer (including the elastomer of the comparative example) was evaluated according to the following criteria. It should be noted that this evaluation was performed on both cyclopentanone and toluene.

[0255] 〔Benchmark〕

[0256] A: No precipitate or the like was observed in either cyclopentanone or toluene, and the polymer was uniformly dissolved.

[0257] B: Slight precipitation was observed, but within a non-problematic range.

[0258] C: Precipitates and the like were observed in either or both of the cyclopentanone and toluene solvents.

[0259] [tack]

[0260] The tack test was conducted by stacking a glass plate, a sheet (elastic body), and a screen printing plate in sequence, and pressing the surface of the screen printing plate against the sheet with a scraper. The test was conducted on both the front and back sides of the sheet. Comparative Example 2 was formed into a sheet by bulk polymerization, and therefore, the test was conducted on both sides separately without distinguishing between the front and back sides as described above.

[0261] Specifically, the obtained sheet (elastic body) was cut into 100 mm in length and 100 mm in width, and the sandblasting film was peeled off from the surface (measurement surface) on the side where the stickiness was measured as needed, and the sheet was placed on a glass plate (300 mm in length and 300 mm in width) so that the measurement surface was on the upper side. At this time, the sheet was placed so that the surface on the opposite side of the measurement surface was in contact with the glass plate and the center of the sheet surface overlapped with the center of the glass plate. Thereafter, static electricity of the sheet was removed by a static eliminator.

[0262] Next, a screen printing plate (manufactured by SERIA, product name: 120424_for manual printing, screen specification: SUS500 (calendered yarn thickness 23 μm)) from which static electricity was removed by a static eliminator was placed on the measuring surface side of the sheet. The screen printing plate was placed on a member disposed at both ends of the glass plate at a distance of about 10 mm from the measuring surface of the sheet.

[0263] After the printing plate is set, the screen printing plate is pressed from the upper surface of the printing plate with a scraper and moved from left to right once, and the printing plate is pushed against the measuring surface of the sheet. Thereafter, the state of the measuring surface of the sheet is visually observed, and the tackiness of the sheet is evaluated according to the following criteria.

[0264] <Standards>

[0265] A: The sheet was not attached to the screen printing plate.

[0266] B: The sheet was attached to the screen printing plate, but deformation of the sheet was not observed when the sheet was peeled off from the screen printing plate with fingers.

[0267] C: The sheet adhered to the screen printing plate and could not be peeled off, or even if it could be peeled off, deformation and breakage were observed in the peeled sheet.

[0268] [Measurement of Young's modulus, strain, and hysteresis]

[0269] The test piece was punched into a dumbbell No. 7 shape specified in 6.1 of JIS K6251. The obtained test piece was mounted in a tensile testing machine [manufactured by A&D Co., Ltd., product number: Tensilon RTG-1310] so that the distance between the chucks was 17 mm, and a tensile load was applied at a tensile speed of 50 mm / min until the test piece broke, and the Young's modulus and the strain (elongation) at the time of the test piece breaking were measured.

[0270] In addition, the elongation of the film obtained above was calculated|required based on the following formula.

[0271] Formula: [Film elongation (%)] = [Length of test piece at break (mm) - original length of test piece (mm)] ÷ [Original length of test piece (mm)] × 100

[0272] [Determination of hysteresis]

[0273] Regarding hysteresis, hysteresis loss and residual strain, which are evaluation indices, were derived. Specifically, the following measurements were performed using the above-mentioned test piece and tensile testing machine, and the hysteresis loss and residual strain were calculated using the obtained graph.

[0274] In the measurement, for the test piece, the operation of applying a tensile load until the elongation is 100% (the operation of making the distance between the chucks 34 mm) and the operation of restoring the test piece that has reached 100% to 0% (the operation of restoring the distance between the chucks of 34 mm to 17 mm) (both at 50 mm / min) are regarded as one cycle, and two cycles are performed. The hysteresis loss and residual strain are calculated from the curve graph of the measurement results of the second cycle.

[0275] use Figure 1 , the calculation method of hysteresis loss and residual deformation is explained in detail. Figure 1 It is a graph for explaining hysteresis loss and residual deformation.

[0276] For hysteresis loss, Figure 1 The area enclosed by the dotted line (outbound) and the solid line (return) is calculated. The smaller the hysteresis loss, the better the tracking performance.

[0277] For residual deformation, Figure 1 As described in, the difference between the line segment A from the rising point (the point with the strain value when 0 MPa is added during the outward journey) to the maximum load and the line segment B from the recovery point (the point with the strain value when the same stress value as when 0 MPa is added during the return journey) to the maximum load is calculated from the deformation (residual deformation) = (AB).

[0278] [Table 1]

[0279]

[0280] In the table, the so-called "macromonomer ratio in the curable resin composition" refers to the amount of the macromonomer (mass %) relative to the total amount of the copolymer (X) and the macromonomer in the curable resin composition in the Examples and Comparative Example 1, and in Comparative Example 2, the amount in the curable resin composition refers to the amount of the macromonomer (mass %) relative to the total amount of all monomers.

[0281] As can be seen from Table 1, the copolymers (X) obtained in Examples and Comparative Example 1 were both excellent in solubility in solvents.

[0282] Furthermore, the sheet (elastic body) of the example can be made into a thin film of less than 0.3 mm while maintaining low tackiness, and can be suitably used as a non-sticky sheet.

[0283] On the other hand, the sheet (elastomer) of Comparative Example 1 in which no macromonomer was used had a high degree of stickiness when formed into a film, and was therefore not suitable for use as a non-sticky sheet.

[0284] In addition, the sheet (elastomer) of Comparative Example 2 which did not have the monomer (C) as a side chain could not be dissolved in a solvent for coating, and could not be formed into a thin film of less than 0.3 mm.

[0285] The entire disclosure of Japanese Patent Application No. 2019-140535 filed on July 31, 2019 is incorporated into this specification by reference.

[0286] In addition, all documents, patent applications, and technical standards described in the specification are incorporated into this specification by reference to the same extent as if each document, patent application, and technical standard was specifically and individually described.

[0287] Industrial Applicability

[0288] The (meth)acrylic elastomer of the present invention can be suitably used for a base film of FPC, a protective film of a substrate for electronic components, a medical material, a health material, a life science material, a robot material, and the like.

Claims

1. A curable resin composition comprising a copolymer (X) and a macromonomer having a functional group polymerizable with a (meth)acryloyl group at a single terminal, wherein the copolymer (X) comprises: a main chain including a structural unit derived from an alkyl (meth)acrylate monomer (A) and a structural unit derived from a hydroxyalkyl (meth)acrylate monomer (B); and A side chain that is bonded to the structural unit (B) and includes a structural unit derived from an isocyanate-based monomer (C) having a (meth)acryloyl group.

2. The curable resin composition according to claim 1, wherein The (meth)acrylic acid alkyl ester monomer (A) is represented by the following formula (1): [Chemical formula 1] In formula (1), R 1 Represents a hydrogen atom or a methyl group; R 2 The group represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, which may have a halogen atom or an ether bond, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms.

3. The curable resin composition according to claim 1 or 2, wherein The (meth)acrylate hydroxyalkyl ester monomer (B) is represented by the following formula (2): [Chemical formula 2] In formula (2), R 1 represents a hydrogen atom or a methyl group; Z represents O, NH, or S; X 1 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms or an aryl group, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms, which may have a halogen atom; and a represents an integer greater than 1.

4. The curable resin composition according to claim 1 or 2, wherein The isocyanate monomer (C) is a compound represented by the following formula (3-1): [Chemical formula 3] In formula (3-1), R 1 represents a hydrogen atom or a methyl group; X 2 It represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or a linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms which may have a hydroxyl group.

5. The curable resin composition according to claim 1 or 2, wherein The macromonomer has a (meth)acryloyl group as the functional group.

6. The curable resin composition according to claim 1 or 2, wherein The content of the macromonomer is 1 to 50% by mass based on the total amount of the copolymer (X) and the macromonomer.

7. The curable resin composition according to claim 1 or 2, further comprising a surfactant.

8. The curable resin composition according to claim 1 or 2, further comprising a polymerization initiator. 9 . The curable resin composition according to claim 1 , further comprising a solvent. 10 . An elastomer obtained by reacting the curable resin composition according to claim 1 .

11. An elastomer represented by the following formula (5), [Chemical formula 4] In formula (5), R 1 Represents a hydrogen atom or a methyl group; R 2 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, which may have a halogen atom or an ether bond, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms; Z represents O, NH, or S; X 1 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group, or a linear, branched or cyclic alkoxyalkyl group having 2 to 12 carbon atoms, which may have a halogen atom; X 2 represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or a linear, branched or cyclic alkoxyalkylene group having 2 to 12 carbon atoms which may have a hydroxyl group; M 1 It represents a structural unit derived from a macromonomer having a functional group capable of polymerizing with a (meth)acryloyl group at a single terminal; 1 、m 1 and O 1 It represents the molar ratio of each structural unit.

12. A sheet comprising the elastomer according to claim 10 or 11.

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