WO2020017545A1 - Curable resin composition, (meth)acrylic elastomer, and sheet - Google Patents

Abstract

A curable resin composition which contains: a (meth)acrylic monomer; a crosslinkable monomer which has two or more functional groups that are polymerizable with a (meth)acryloyl group; and a macromonomer which has, at least at one end, a functional group that is polymerizable with a (meth)acryloyl group.

Description

Curable resin composition, and (meth) acrylic elastomer and sheet

The present invention relates to a curable resin composition, and a sheet such as a (meth) acrylic elastomer and a flexible sheet or a stratable sheet. In detail, Flexible Printed Circuits such as a flexible printed circuit board, a sheet that can be suitably used as a protective film of a circuit board and a wiring board, and the like, and a curable resin composition used for manufacturing the sheet and the like and ( It relates to a (meth) acrylic elastomer.

需要 In recent years, the demand for sheets used for electronic components has been increasing. For example, as electronic products become lighter, smaller, and denser, attention is paid to so-called Flexible Printed Circuits (hereinafter, sometimes referred to as “FPC”) called flexible printed circuit boards or flexible printed wiring boards. Is also growing. The FPC is formed by using an insulating film as a base film (also referred to as a substrate), bonding a metal foil through an adhesive layer or the like, or forming a pattern formed of a conductive ink or a film. In such an FPC, a resin sheet having elasticity and flexibility using various materials is used as a base film (for example, Patent Document 1).

In addition, resin sheets can be applied to various uses such as protection of electronic member substrates, and, for example, have been developed according to various uses such as used for adhesive tapes and dielectric materials. (For example, see Patent Documents 2 and 3). Further, a resin film for FPC is also being developed.

JP, 2017-145325, A JP 2014-105325 A JP-A-2017-132905

(4) When a resin sheet is used for an FPC application or a protection application, the material is required to have flexibility in order to sufficiently exhibit elasticity, and a material having a low Young's modulus is being developed. However, a resin film having excellent flexibility (having a low Young's modulus) generally has high tackiness and often exhibits a property of sticking to other members. As described above, materials having high tackiness have poor handleability, and for example, improvement is required from the viewpoint of transportability in a device such as a screen printing device. On the other hand, low tackiness and low Young's modulus are contradictory properties, and development of a material having these properties in a well-balanced manner has been desired.

In order to solve the above-described problems, the present invention provides a curable resin composition capable of producing a (meth) acrylate-based elastomer in which low tackiness and a low Young's modulus are well-balanced, and a curable resin composition using the same. ) It is intended to provide an acrylic elastomer and a sheet.

<1> (meth) acrylic monomer,
A crosslinkable monomer having two or more functional groups capable of polymerizing with a (meth) acryloyl group,
A macromonomer having at least one terminal with a (meth) acryloyl group and a polymerizable functional group;
A curable resin composition comprising:
<2> The curable resin composition according to <1>, wherein the crosslinkable monomer is a (meth) acrylate compound having two or more (meth) acryloyl groups as the functional group.
<3> The curable resin composition according to <1> or <2>, wherein the macromonomer is at least one selected from a styrene macromonomer and a polyacrylate macromonomer.
<4> The curable resin composition according to any one of <1> to <3>, wherein the macromonomer has a (meth) acryloyl group as the functional group.
<5> The curable resin composition according to any one of <1> to <4>, wherein the (meth) acrylic monomer is an acrylic monomer.
<6> The curable resin composition according to <5>, wherein the acrylic monomer is at least one selected from ethyl acrylate and methoxyethyl acrylate.
<7> The curable resin composition according to any one of <1> to <6>, wherein the content of the macromonomer is 6 to 15% by mass based on the total solid content.
<8> The method according to any one of <1> to <7>, wherein the crosslinkable monomer is contained in an amount of more than 0.25 to less than 5.0 mol% based on the total amount of the (meth) acrylic monomer. Curable resin composition.
<9> The curable resin composition according to any one of <1> to <8>, further including a photopolymerization initiator.
<10> A (meth) acrylic elastomer obtained by polymerizing the curable resin composition according to any one of <1> to <9>.
<11> A sheet obtained by polymerizing the curable resin composition according to any one of <1> to <9>.
<12> The sheet according to <11>, having a processed surface subjected to a surface treatment.
<13> The sheet according to <12>, wherein the surface treatment is blasting.
<14> The sheet according to any one of <11> to <13>, wherein the arithmetic average roughness Ra (nm) of at least one surface is 50 to 300.
<15> The sheet according to any one of <11> to <14>, wherein the curable resin composition is subjected to bulk polymerization.

ADVANTAGE OF THE INVENTION According to this invention, the curable resin composition which can produce the (meth) acrylate-type elastomer which made low tackiness and low Young's modulus compatible well, and the (meth) acrylic-type elastomer and sheet using the same. Can be provided.

5 is a graph for explaining hysteresis loss and residual strain.

<< Curable resin composition >>
The curable resin composition of the present embodiment includes a (meth) acrylic monomer and a crosslinkable monomer having two or more functional groups capable of polymerizing with a (meth) acryloyl group (hereinafter, may be simply referred to as a “crosslinkable monomer”). And a macromonomer having a (meth) acryloyl group and a polymerizable functional group at at least one terminal (hereinafter, may be simply referred to as “macromonomer”). Throughout this specification, “(meth) acryl” means “acryl” or “methacryl”, and “(meth) acrylate” means “acrylate” or “methacrylate”. When simply referred to as "alkyl group", it includes an alkyl group having a linear, branched or alicyclic structure.

The curable resin composition of the present embodiment contains a (meth) acrylic monomer, a crosslinkable monomer, and a macromonomer, and has a good balance between low tackiness and low Young's modulus by polymerizing each monomer component. The achieved (meth) acrylic elastomer can be synthesized.

<(Meth) acrylic monomer>
In the present embodiment, the “(meth) acrylic monomer” is a monomer having one (meth) acryloyl group, and is distinguished from a crosslinkable monomer and a macromonomer in the present embodiment described later.
As the (meth) acrylic monomer in the present embodiment, for example, a compound represented by the following formula (I) can be used.

（式中、Ｒ¹は水素原子又はメチル基；Ｒ²は水酸基もしくはハロゲン原子を有していてもよい炭素数１～１０のアルキル基、又は、水酸基を有していてもよい炭素数２～１２のアルコキシアルキル基を示す）

(Wherein R ¹ is a hydrogen atom or a methyl group; R ² is an alkyl group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom, or 2 to 2 carbon atoms which may have a hydroxyl group) 12 represents an alkoxyalkyl group)

In the (meth) acrylic monomer represented by the formula (I), R ¹ is a hydrogen atom or a methyl group. R ¹ is preferably a hydrogen atom from the viewpoint of obtaining an elastomer having low Young's modulus and low hysteresis. That is, the (meth) acrylic monomer is preferably an acrylic monomer.

In the compound represented by the formula (I), R2 is an alkyl group having 1 to 10 carbon atoms which may have a hydroxyl group or a halogen atom or an alkoxyalkyl group having 2 to 12 carbon atoms which may have a hydroxyl group. It is.

Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, Examples include an isoamyl group, an n-hexyl group, an isohexyl group, a cyclohexyl group, an n-octyl group, and the like, but the present embodiment is not limited to such an example.

Examples of the alkyl group having 1 to 10 carbon atoms having a hydroxyl group include a hydroxymethyl group, a hydroxyethyl group, a hydroxy n-propyl group, a hydroxyisopropyl group, a hydroxy n-butyl group, a hydroxyisobutyl group, and a hydroxytert-butyl group. However, the present embodiment is not limited only to such an example.

ハ ロ ゲ ン Examples of the halogen atom contained in the alkyl group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Since the number of halogen atoms contained in the alkyl group depends on the number of carbon atoms of the alkyl group and the like and cannot be unconditionally determined, it is preferable to appropriately adjust the number within the range where the object of the present embodiment is not hindered.

Examples of the alkyl group having 1 to 10 carbon atoms having a halogen atom include a trifluoromethyl group, a trifluoroethyl group, a trifluoron-propyl group, a trifluoroisopropyl group, a trifluoron-butyl group and a trifluoroisobutyl group. , Trifluorotert-butyl group and the like, but the present embodiment is not limited only to such an example.

Examples of the C2 to C12 alkoxyalkyl group include a C1 to C6 alkoxy group such as a methoxyethyl group, an ethoxyethyl group and a methoxybutyl group, and an alkoxyalkyl group having a C1 to C6 alkyl group. However, the present embodiment is not limited only to such an example.

Examples of the alkoxyalkyl group having 2 to 12 carbon atoms having a hydroxyl group include a hydroxyalkoxy group having 1 to 6 carbon atoms such as a hydroxymethoxyethyl group, a hydroxyethoxyethyl group and a hydroxymethoxybutyl group, and an alkyl group having 1 to 6 carbon atoms. Examples thereof include an alkoxyalkyl group having a group, but the present embodiment is not limited only to such an example.

Among R ² , from the viewpoint of the solubility of the macromonomer, an alkyl group having 1 to 10 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms that does not have a hydroxyl group or a halogen atom is preferable, and has a low Young's modulus and low hysteresis. From the viewpoint of obtaining an elastomer having the following, an alkyl group having 1 to 4 carbon atoms or an alkoxyalkyl group having 1 to 4 carbon atoms is preferable, and an ethyl group and a methoxyethyl group are more preferable.

Examples of the (meth) acrylic monomer represented by the formula (I) 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, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, methylpentyl (meth) acrylate In formula (I) such as n-octyl (meth) acrylate, nonanol (meth) acrylate, and cyclohexyl (meth) acrylate, R ¹ is a hydrogen atom or a methyl group, and R ² is an alkyl group having 1 to 10 carbon atoms. (Meth) acrylic Monomer: In formula (I) such as hydroxypropyl (meth) acrylate or hydroxybutyl (meth) acrylate, R ¹ is a hydrogen atom or a methyl group, and R ² is a hydroxyl group-containing alkyl group having 1 to 10 carbon atoms. (Meth) acrylic monomer; in the formula (I) such as 2,2,2-trifluoroethyl acrylate, R ¹ is a hydrogen atom or a methyl group, and R ² is a halogen-containing alkyl having 1 to 10 carbon atoms. (Meth) acrylic monomer which is a group; methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxybutyl (meth) acrylate, phenoxyethyl acrylate, (2-methyl-2-ethyl-1,3-dioxolane- In formula (I) such as 4-yl) methyl acrylate, R ¹ represents a hydrogen atom or A (meth) acrylic monomer in which R ² is an alkoxyalkyl group having 2 to 12 carbon atoms; and R ¹ is a hydrogen atom or a methyl group in formula (I) such as diethylene glycol mono (meth) acrylate. And a (meth) acrylic monomer in which R ² is an alkoxyalkyl group having 2 to 12 carbon atoms having a hydroxyl group.
Among these, as the (meth) acrylate-based elastomer in the present embodiment, ethyl (meth) acrylate and methoxyethyl (meth) acrylate are more preferred, acrylic monomers are preferred, and ethyl acrylate and methoxyethyl acrylate are even more preferred.
These (meth) acrylic monomers may be used alone or in combination of two or more.

<Crosslinkable monomer>
In the present embodiment, the “crosslinkable monomer” means a monomer having two or more functional groups capable of polymerizing with a (meth) acryloyl group (hereinafter, may be simply referred to as “functional groups”).
Examples of the crosslinkable monomer include, as functional groups, two or more (meth) acryloyl groups such as alkylenebis (meth) acrylamide having 1 to 4 carbon atoms in an alkylene group such as methylenebisacrylamide and methylenebismethacrylamide; (Meth) acrylamide compound preferably having two; as a functional group, ethylene di (meth) acrylate, ethylene glycol di (meth) acrylate (“EGDMA”), diethylene glycol di (meth) acrylate (“DEDMDMA”), propylene glycol diamine (Meth) acrylate, triethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, -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, trimethylol (Meth) acrylate compounds having two or more (meth) acryloyl groups, preferably two or three, such as propane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and nonaethylene glycol di (meth) acrylate; An amine compound having two or more, preferably two or three, carbon-carbon double bonds such as diallylamine and triallylamine as a group; and a carbon-carbon double bond such as divinylbenzene and diallylbenzene as a functional group. Or more, preferred It can be mentioned polyfunctional monomers such as aromatic compounds having two or three.
Among these, as the crosslinkable monomer in the present embodiment, the crosslinkable monomer has two or more (meth) acryloyl groups as the functional group from the viewpoint of obtaining an elastomer having low tackiness and low hysteresis (meth) ) Acrylate compounds are preferred, EGDMA, DEGDMA, tetraethylene glycol di (meth) acrylate, and nonaethylene glycol di (meth) acrylate are more preferred. From the viewpoint of a further lower Young's modulus, EGDMA and DEGDMA are more preferred, and DEGDMA is particularly preferred. .
However, the crosslinkable monomer in the present embodiment is not limited only to such an example. The crosslinkable monomers may be used alone or in combination of two or more.

<Macromonomer>
A “macromonomer” is a molecule that functions as a monomer molecule, that is, a molecule that can serve as a structural unit of the basic structure of a polymer, and is a polymer having a polymerizable group. The macromonomer in this embodiment has a functional group capable of polymerizing with a (meth) acryloyl group at at least one terminal.
Examples of the “functional group capable of polymerizing with a (meth) acryloyl group” included in the macromonomer according to the present embodiment include the functional group included in the crosslinkable monomer described above.

数 The number average molecular weight of the macromonomer is not particularly limited, but is preferably 1,000 or more, more preferably 2,500 or more, and particularly preferably 5,000 or more from the viewpoint of low tackiness. The number average molecular weight of the macromonomer is determined by gel permeation chromatography [manufactured by Tosoh Corporation, product number: HLC-8320GPC, column: manufactured by Tosoh Corporation, product number: Super @ H2500, solvent: tetrahydrofuran, flow rate: 0.6 mL / min] in terms of polystyrene.

The macromonomer in the present embodiment is not particularly limited, but from the viewpoint of low tackiness, a polystyrene-based macromonomer having an acryloyl group as a functional group at least at one end, preferably at one end; an acryloyl group as a crosslinkable group A polyacrylate-based macromonomer having at least a terminal, and preferably both terminals, is exemplified. As these macromonomers, those commercially available can be appropriately selected. For example, macromonomers manufactured by Toagosei Chemical Co., Ltd. (eg, product name: AS-6 (polystyrene-based macromonomer), product name AA-6 (polyacrylate-based macromonomer)) and the like.

<Curable resin composition>
The (meth) acrylic elastomer obtained by polymerizing the curable resin composition of the present embodiment can achieve both tacklessness (low tackiness) and low Young's modulus.

The content of the (meth) acryloyl-based monomer in the curable resin composition is not particularly limited, but is preferably from 75 to 92% by mass, and preferably from 80 to 90% by mass based on the total solid content from the viewpoint of low hysteresis. Is more preferable, and 85 to 88% by mass is particularly preferable.

The content of the crosslinkable monomer in the curable resin composition is not particularly limited, but is preferably more than 0.25 to 5.0 with respect to the total amount of the acrylic monomer from the viewpoint of low Young's modulus and low hysteresis. Less than mol% is more preferable, 0.5 to 4.0 mol% is further preferable, and 0.75 to 1.5 mol% is particularly preferable.

The content of the macromonomer in the curable resin composition is not particularly limited, but is preferably 6 to 15% by mass, more preferably 7 to 12% by mass, based on the total solid content, from the viewpoint of low tackiness. And 10 to 15% by mass are particularly preferred.

The curable resin composition of the present embodiment may contain the above-mentioned (meth) acrylic monomer, crosslinkable monomer, and macromonomer (hereinafter, these may be collectively referred to as “monomer components in the present embodiment”). However, other components may be contained as desired.

(Polymerization initiator)
The curable resin composition can use a polymerization initiator to polymerize the monomer component in the present embodiment. Examples of the polymerization initiator include a photopolymerization initiator and a thermal polymerization initiator. Among these polymerization initiators, a photopolymerization initiator is preferable from the viewpoint of keeping no thermal history in the (meth) acrylic elastomer.

Examples of the photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,1 '-Biimidazole, 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenylvinyl) -1,3,5 -Triazine, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, 4,4'-ditert-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, benzoin, 2-hydroxy-2-methyl- 1-phenylpropane-2- Benzophenone, thioxanthone, 2,4,6-trimethylbenzoyldiphenylacylphosphine oxide, triphenylbutyl borate tetraethylammonium, diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, 2,2-dimethoxy-1,2-diphenylethane -1-one, phenylglyoxylic acid methyl ester, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, bis (2,4,6-trimethylbenzoyl)- Phenylphosphine oxide, 1,2-octanedione, 1- [4- (phenylthio) -2- (o-benzoyloxime)], bis (η5-2,4-cyclopentadien-1-yl) bis [2 6-difluoro-3- (1H -Pyrrole-1-yl) phenyltitanium], 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (P-methoxyphenylvinyl) -1,3,5-triazine, diphenyliodonium tetrafluoroborate, 4,4′-ditert-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, diphenyl-4 Examples include photocationic ring-opening polymerization initiators such as -phenylthiophenylsulfonium hexafluorophosphate, but the present embodiment is not limited to such examples. These photopolymerization initiators may be used alone or in combination of two or more.

Examples of the thermal polymerization initiator include dimethyl-2,2′-azobis (2-methylpropionate), 2,2′-azobisisobutyronitrile (AIBN), dimethyl 2,2′-azobisisobutyrate, Examples include azo-based polymerization initiators such as azobisdimethyl valeronitrile, and peroxide-based polymerization initiators such as benzoyl peroxide, potassium persulfate, and ammonium persulfate, but the present embodiment is limited to only such examples. Not something. These polymerization initiators may be used alone or in combination of two or more.

(4) The amount of the polymerization initiator varies depending on the type of the polymerization initiator and the like, and cannot be unconditionally determined. However, it is usually preferably about 0.01 to 20 parts by mass per 100 parts by mass of the monomer component.

(Chain transfer agent)
In the curable resin composition, when polymerizing the monomer component in the present embodiment, a chain transfer agent can be used to adjust the molecular weight of the obtained (meth) acrylic elastomer. Examples of the chain transfer agent include compounds having a thiol group such as lauryl mercaptan, dodecyl mercaptan, and thioglycerol; and inorganic salts such as sodium hypophosphite and sodium bisulfite. It is not limited to only. These chain transfer agents may be used alone or in combination of two or more. Since the amount of the chain transfer agent varies depending on the type of the chain transfer agent and the like, it cannot be determined unconditionally. However, it is usually preferably about 0.01 to 10 parts by mass per 100 parts by mass of the monomer component.

(Other monomers)
The curable resin composition may contain a monomer component other than the monomer component in the present embodiment, depending on desired characteristics. Examples of the other monomer include a carboxyl group-containing monomer, a carboxylic acid alkyl ester monomer other than the (meth) acrylic monomer represented by the formula (I), an amide group-containing monomer, an aryl group-containing monomer, a styrene-based monomer, and nitrogen. Examples thereof include an atom-containing monomer, a fatty acid vinyl ester-based monomer, and a betaine monomer, but the present embodiment is not limited to only such examples. These monomers may be used alone or in combination of two or more.

<< (meth) acrylic elastomer >>
As described above, the (meth) acrylic elastomer obtained by polymerizing the curable resin composition of the present embodiment can achieve both tacklessness (low tackiness) and low Young's modulus.

The glass transition temperature of the (meth) acryloyl-based elastomer is not particularly limited, but is preferably −50 ° C. or higher, and more preferably −20 ° C. or higher, from the viewpoint of low tackiness and low Young's modulus. The glass transition temperature of the (meth) acryloyl-based elastomer can be determined by the method described in Examples described later.

As a method of polymerizing the curable resin composition, for example, a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and the like, but the present embodiment is not limited to only such examples. Absent. Among these polymerization methods, from the viewpoint of low tackiness, low Young's modulus, and low hysteresis, a bulk polymerization method and a solution polymerization method are preferable, and further, from the viewpoint of low tackiness and low hysteresis, a bulk polymerization method is preferable. More preferred. The (meth) acrylic elastomer of the present embodiment has a low extensibility and low elongation when the monomer component of the raw material is not polymerized by the suspension polymerization method like the conventional acrylic rubber but by the bulk polymerization method. A (meth) acrylic elastomer excellent in tackiness and low hysteresis can be easily prepared.

溶媒 A solvent is used when polymerizing the curable resin composition by a solution polymerization method. Among the solvents, non-aqueous organic solvents are preferred. Examples of the non-aqueous organic solvent include hydrocarbon organic solvents such as hexane, heptane, octane, isooctane, decane, and liquid paraffin; ether organic solvents such as dimethyl ether, diethyl ether, and tetrahydrofuran; ketone organic solvents such as acetone and methyl ethyl ketone. Solvents; ester organic solvents such as methyl acetate, ethyl acetate and butyl acetate; chloride organic solvents such as methylene chloride, chloroform and carbon tetrachloride; dimethylformamide, diethylformamide, dimethylsulfoxide, dioxane and the like. Embodiments are not limited to only such examples. These organic solvents may be used alone or in combination of two or more. Since the amount of the solvent varies depending on the type of the solvent, it cannot be unconditionally limited, but is usually preferably about 100 to 1,000 parts by mass per 100 parts by mass of the monomer component.

The atmosphere for polymerizing the curable resin composition is not particularly limited, and may be air or an inert gas such as nitrogen gas or argon gas.

温度 The temperature at which the curable resin composition is polymerized is not particularly limited, and is usually preferably about 5 to 100 ° C. The time required for polymerizing the monomer component is arbitrary because it cannot be unconditionally determined because it varies depending on the polymerization conditions, but is usually about 0.25 to 20 hours.

The polymerization reaction can be arbitrarily terminated when the amount of the remaining monomer component becomes 20% by mass or less. The amount of the remaining monomer component can be measured by using, for example, gel permeation chromatography.

形状 The shape such as width, thickness, and length of the (meth) acrylic elastomer obtained by polymerizing the curable resin composition of the present embodiment is not particularly limited.

《Sheet》
The sheet of the present embodiment can be obtained by polymerizing a curable resin composition. More specifically, a sheet can be manufactured using the (meth) acrylic elastomer described above. In this case, for example, a film-like sheet made of a (meth) acrylic elastomer is cast by casting the monomer component on a substrate and polymerizing the monomer component by irradiating ultraviolet rays to the formed film of the monomer component. Obtainable.
In other words, the (meth) acrylic elastomer obtained by polymerizing the curable resin composition of the present embodiment can be said to be a wide sheet having a certain thickness or less as the sheet of the present embodiment. Since the sheet of the present embodiment is excellent in flexibility, stretchability and elasticity, it can be suitably used as a flexible sheet or a stretchable sheet.

The thickness of the sheet is not particularly limited, but is preferably about 10 μm to 5 mm from the viewpoint of obtaining a sheet having both low tackiness and low Young's modulus.

The sheet can be used as it is depending on the application, but from the viewpoint of imparting toughness, it is preferably uniaxially or biaxially stretched, and more preferably biaxially stretched. From the viewpoint of imparting toughness, the stretching ratio of the film is preferably 1.2 times or more, more preferably 1.5 times or more, and still more preferably 2 times or more, although it depends on the thickness of the sheet. From the viewpoint of preventing breakage during stretching, it is preferably 8 times or less, more preferably 6 times or less, and still more preferably 5 times or less. When the sheet is stretched, it may be heated if necessary.

シ ー ト The sheet of the present embodiment may contain an appropriate amount of another polymer in order to adjust the viscosity.

Other polymers include, for example, acrylic resin, polyacrylonitrile, poly (meth) acrylamide, polyamide, polyvinyl chloride, polyurethane, polyester, carboxymethyl cellulose, and the like, but the present embodiment is limited to only such examples. Not something. These other polymers may be used alone or in combination of two or more.

シ ー ト The sheet of the present embodiment may contain a neutralizing agent, if necessary. Examples of the neutralizing agent include inorganic basic compounds such as sodium hydroxide and potassium hydroxide; monoethanolamine, dimethylethanolamine, diethylethanolamine, triethanolamine, morpholine, aminomethylpropanol, aminomethylpropanediol, octyl Examples include organic basic compounds such as amine, tributylamine, and aniline. However, the present embodiment is not limited to these examples. These neutralizing agents may be used alone or in combination of two or more.

シ ー ト The sheet of the present embodiment may contain additives within a range that does not impair the purpose of the present embodiment. Examples of the additive include a colorant, an antioxidant, an ultraviolet absorber, an antioxidant, a thermally conductive filler, a conductive filler, and the like.However, the present embodiment is not limited to only such an example. Absent.

か ら From the viewpoint of low tackiness, the sheet of the present embodiment preferably has a processed surface subjected to a surface treatment. The surface treatment is not particularly limited, and includes, for example, blast processing (irregular processing). Here, “blasting” in the present embodiment refers to forming a film using a blasted mold, or using a film produced using the mold as a release film, This is a concept including a mode of transferring a pattern formed on a film to a sheet surface. For example, sand of fine particles can be blown into a mold cavity by using air or the like to make a very small flaw, and can be transferred to the sheet surface using the mold. The pattern transferred to the sheet surface is affected by surface tension and curing shrinkage, and the surface roughness of the release film is not always transferred as it is.

In addition, the arithmetic average roughness (Ra) of at least one surface of the sheet of the present embodiment is preferably from 50 to 1,000, more preferably from 50 to 500, and particularly preferably from 50 to 300, from the viewpoint of low tackiness. preferable. As a method for measuring the arithmetic average roughness, for example, a method described in Examples described later can be used.

The Young's modulus, the maximum point stress, and the elongation (Strain) of the sheet of the present embodiment can be measured, for example, using a tensile measurement device according to JIS K6251.
The Young's modulus of the sheet of this embodiment is preferably about 6.00 MPa or less, and more preferably 4.50 MPa or less.
The Strain of the sheet of the present embodiment is preferably from 50 to 2000%, more preferably from 100 to 1000%, and particularly preferably from 500 to 700%, from the viewpoint of high elongation.

The hysteresis of the sheet of the present embodiment can be measured by a method described in Examples described later. Specifically, the hysteresis can be evaluated by measuring “residual strain” and “hysteresis loss” of the sheet and using these as one index.
The low compression set of the sheet of the present embodiment is preferably 10.0 MPa ·% or less, more preferably 5.0 MPa ·% or less, and particularly preferably 3.0 MPa ·% or less.
The residual strain of the sheet of the present embodiment is preferably 10.0% or less, more preferably 5.0% or less, and particularly preferably 3.0% or less.

Since the sheet of the present embodiment can exhibit low tackiness and low Young's modulus in a well-balanced manner, the base film of FPC, the protective film of the substrate for electronic members, the medical material, the health care material, the life science material, or the robot material And the like.

Next, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to only these examples.

[Example 1]
50.02 g of ethyl acrylate, 1.22 g of diethylene glycol dimethacrylate (DEDMMA) (1 mol% based on ethyl acrylate), 5.69 g of polystyrene-based macromonomer (manufactured by Toagosei Chemical Co., Ltd., trade name: AS-6) (composition) (10% by mass based on the total solid content in the product) and 0.0314 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name: IrgacureTPO, manufactured by BASF) as a polymerization initiator. A curable resin composition containing an initiator was obtained.

The obtained curable resin composition was molded into a transparent glass mold (0.3 mm thick silicon spacer, to which a blasted release film (arithmetic mean roughness (JIS B 0601): 430 nm)) was attached. Length: 100 mm, width: 100 mm, thickness: 0.3 mm). Next, the curable resin composition was irradiated with ultraviolet rays for 2 hours so that the irradiation dose of the curable resin composition was 0.20 mW / cm ² on the mold set in a water bath, and the monomer components were mass-polymerized. Thereafter, the mold was taken out of the water bath, and a sheet made of the (meth) acrylic elastomer was taken out of the mold. Thereafter, the sheet was dried under the conditions of 0.01 MPa or less and 80 ° C. for 3 hours, and parameters described later were measured.

[Example 2]
A sheet was obtained in the same manner as in Example 1 except that a release film not subjected to blasting was used instead of the release film subjected to blasting.

[Comparative Examples 1-2]
A sheet was obtained in the same manner as in Examples 1 and 2, except that the crosslinking monomer (diethylene glycol dimethacrylate) was not used.

[Comparative Examples 3 and 4]
A sheet was obtained in the same manner as in Examples 1 and 2, except that no macromonomer was used.

[Comparative Examples 5 and 6]
A sheet was obtained in the same manner as in Examples 1 and 2, except that the crosslinking monomer and the macromonomer were not used.

《Evaluation》
The physical properties of the sheets of the examples and comparative examples were measured according to the methods described below. Table 1 shows the results.

[Arithmetic average roughness (Ra)]
The arithmetic average roughness of the sheet surface was determined for Examples 1 and 2 and Comparative Examples 3 and 4 by analyzing image data obtained by the following scanning probe microscope. Specifically, the obtained image is subjected to tilt correction (average value in the X direction and average value in the Y direction), and after removing noise lines, arithmetically averaging the entire measurement range (20 μm square). Roughness analysis was performed. In the measurement, the arithmetic average roughness within the measurement range is indicated as a value exceeding the value indicated as the minimum value and less than the value indicated as the maximum value. For each sheet, three places were measured by the above-mentioned measuring method, and the lowest value and the highest value were the lowest (highest) values of the three places as the lowest value and the highest value of the sheet. Table 1 shows the results.

〔Used equipment〕
Scanning probe microscope: (SPM-9700HT, manufactured by Shimadzu Corporation)
Cantilever: (NanoWorld, NHCR-10)
Software used: Software originally included in SPM-9700HT Measurement mode: Dynamic mode Scanning range: 20 μm Square scanning speed: 0.1 Hz
Number of pixels: 256 × 256
P gain: 0.001
I gain: 1500
Z range: × 1

[tack]
The sheet was placed on a glass plate, and static electricity was removed with a shunt. Next, a screen printing plate (made by SERIA, product name: 120424_ for manual printing, mesh specification: SUS500 (calendered thickness: 23 μm)) from which static electricity was removed with a gradual reducer was covered from above. Further, the screen printing plate was pressed against the sheet with a squeegee. When the screen printing plate was removed, even a part thereof adhered to the screen printing plate, and when the sheet moved from the original position, it was determined that the sheet was stuck to the screen printing plate. This judgment was performed 10 times for the same sample, and the number of times of sticking was recorded. The smaller the number of sticks, the lower the tackiness and the better.

[Measurement of maximum point stress, elongation (Strain), Young's modulus]
A test piece was obtained by punching the sheet into a dumbbell-shaped No. 7 shape specified in JIS K6251. The obtained test piece was attached to a tensile tester (manufactured by A & D Co., Ltd., product number: Tensilon RTG-1310) so that the distance between the chucks was 17 mm, and the test piece was broken at a pulling speed of 50 mm / min. An operation of applying a tensile load was performed until the maximum stress, elongation (Strain) and Young's modulus were measured.

[Measurement of hysteresis]
With respect to hysteresis, hysteresis loss and residual strain, which are evaluation indices, were derived. In detail, the following measurement was performed using the above-mentioned test piece and the tensile tester, and the hysteresis loss and the residual strain were calculated using the obtained graph.
The measurement was performed by applying a tensile load to the test specimen to 100% elongation (operation to reduce the distance between chucks to 34 mm) and returning the test specimen that reached 100% to 0% (operating to reduce the distance between chucks of 34 mm to 17 mm). Returning operation) (each cycle of 50 mm / min) was defined as one cycle, and two cycles were performed. The hysteresis loss and the residual strain were calculated from the graph of the measurement result of the second cycle.

The method of calculating the hysteresis loss and the residual strain will be described in detail with reference to FIG. FIG. 1 is a graph for explaining hysteresis loss and residual strain.
The area of the hysteresis loss was calculated for a region surrounded by a dotted line (outgoing path) and a solid line (returning path) in FIG. The smaller the hysteresis loss, the better the followability.
As shown in FIG. 1, the residual strain shows a line segment A from the rising point (the point of the strain value at the time of 0 MPa load on the forward path) to the maximum load and the return point (the same stress value as at the time of 0 MPa load on the return path). The strain (residual strain) = (1−B / A) × 100 was calculated using the difference from the line segment B from the point of the strain value at the time) to the maximum load.

As can be seen from Table 1, the sheet of Example 1 has a low Young's modulus and low tackiness. The sheet of Example 2 also had a tackiness measurement result of “5 times”, indicating an acceptable degree of tackiness.
On the other hand, the sheets of the comparative examples exhibited tackiness that was more than allowable.

[Example 3]
A sheet was prepared in the same manner as in Example 1 except that the same amount of a polyacrylate-based macromonomer (manufactured by Toagosei Chemical Co., Ltd., trade name: AA-6) was used instead of the polystyrene-based macromonomer. The same evaluation was performed.

As can be seen from the table, the sheet using the polyacrylate-based macromonomer (polymethylmethacrylate-based macromonomer) has slightly higher Young's modulus and hysteresis loss than Example 1 using the polystyrene-based macromonomer. became.

[Examples 4 to 6]
A sheet was prepared and evaluated in the same manner as in Example 1 except that the amount of the macromonomer (total solid content in the composition) was changed as shown in the following table.

わ か る As can be seen from the table, the tack improved as the amount of macromonomer added increased, and Examples 1 and 5 were superior in terms of Young's modulus, hysteresis loss and residual strain.

[Examples 7 to 9]
A sheet was prepared and evaluated in the same manner as in Example 1 except that the same amount of the crosslinking monomer shown in the following table was used instead of DEGDMA.

　表に記載の各架橋性モノマーは以下のものを示す（いずれも新中村化学工業（株）製）。
・ＮＫエステル１Ｇ：エチレングリコールジ（メタ）アクリレート
・ＮＫエステル２Ｇ：ジエチレングリコールジ（メタ）アクリレート
・ＮＫエステル４Ｇ：テトラエチレングリコールジ（メタ）アクリレート
・ＮＫエステル９Ｇ：ノナエチレングリコールジ（メタ）アクリレート

Each crosslinkable monomer shown in the table is as follows (all are manufactured by Shin-Nakamura Chemical Co., Ltd.).
・ NK ester 1G: Ethylene glycol di (meth) acrylate ・ NK ester 2G: Diethylene glycol di (meth) acrylate ・ NK ester 4G: Tetraethylene glycol di (meth) acrylate ・ NK ester 9G: Nonaethylene glycol di (meth) acrylate

わ か る As can be seen from the table, all sheets are excellent in tackiness, but from the viewpoint of Young's modulus, the sheets of Example 1 and Example 7 are excellent.

[Examples 10 and 11]
A sheet was prepared and evaluated in the same manner as in Example 1, except that the amount of the crosslinkable monomer (based on the amount of ethyl acrylate) was changed as shown in the following table.

わ か る As can be seen from the table, all sheets have excellent tackiness, but from the viewpoint of Young's modulus, the sheets of Example 1 and Example 10 are excellent.

[Examples 12 and 13]
A sheet was prepared and evaluated in the same manner as in Example 1 except that the (meth) acrylate-based monomer was replaced with ethylene acrylate and the same amount of the (meth) acrylate monomer described in the following table was used.

　表に記載の各（メタ）アクリレート系モノマーは以下のものを示す
・２－ＭＴＡ　　　：メトキシエチルアクリレート
・ＥＡ　　　　　　：エチルアクリレート
・ＭＥＤＯＬ－１０：（２－メチル－２－エチル－１，３－ジオキソラン－４－イル）メチルアクリレート

Each of the (meth) acrylate monomers shown in the table is as follows: 2-MTA: methoxyethyl acrylate; EA: ethyl acrylate; MEDOL-10: (2-methyl-2-ethyl-1,3-dioxolane) 4-yl) methyl acrylate

As can be seen from the table, the sheets of Example 1 (using ethylene acrylate) and Example 12 (using methoxyethyl acrylate) are superior in tackiness to the sheet of Example 13 using MEDOL-10. You can see that there is.

The disclosure of Japanese Patent Application No. 2018-135076 filed on July 18, 2018 is incorporated herein by reference in its entirety.
In addition, all documents, patent applications, and technical standards described in the specification should be translated to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference. , Incorporated herein by reference.

The (meth) acrylic elastomer of the present invention can be suitably used as a base film of FPC, a protective film of a substrate for an electronic member, a medical material, a health care material, a life science material, a robot material, or the like.

Claims (15)

(Meth) acrylic monomers,
A crosslinkable monomer having two or more functional groups capable of polymerizing with a (meth) acryloyl group,
A macromonomer having at least one terminal with a (meth) acryloyl group and a polymerizable functional group;
A curable resin composition comprising: The curable resin composition according to claim 1, wherein the crosslinkable monomer is a (meth) acrylate compound having two or more (meth) acryloyl groups as the functional group. The curable resin composition according to claim 1 or 2, wherein the macromonomer is at least one selected from a styrene macromonomer and a polyacrylate macromonomer. 4. The curable resin composition according to claim 1, wherein the macromonomer has a (meth) acryloyl group as the functional group. (5) The curable resin composition according to any one of (1) to (4), wherein the (meth) acrylic monomer is an acrylic monomer. The curable resin composition according to claim 5, wherein the acrylic monomer is at least one selected from ethyl acrylate and methoxyethyl acrylate. The curable resin composition according to any one of claims 1 to 6, wherein the content of the macromonomer is 6 to 15% by mass based on the total solid content. The curable resin composition according to any one of claims 1 to 7, wherein the crosslinkable monomer is contained in an amount of more than 0.25 to less than 5.0 mol% based on the total amount of the (meth) acrylic monomer. . 硬化 The curable resin composition according to any one of claims 1 to 8, further comprising a photopolymerization initiator. A (meth) acrylic elastomer obtained by polymerizing the curable resin composition according to any one of claims 1 to 9. A sheet obtained by polymerizing the curable resin composition according to any one of claims 1 to 9. The sheet according to claim 11, which has a processed surface subjected to a surface treatment. The sheet according to claim 12, wherein the surface treatment is blasting. The sheet according to any one of claims 11 to 13, wherein the arithmetic average roughness Ra (nm) of at least one surface is 50 to 300. The sheet according to any one of claims 11 to 14, wherein the curable resin composition is subjected to bulk polymerization.

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