TWI815929B - Curable resin composition, (meth)acrylic elastomer and sheet - Google Patents

Abstract

The present invention provides a curable resin composition, which includes: (meth)acrylic monomer; a cross-linking monomer having two or more functional groups that can be polymerized with (meth)acrylyl groups; and a macromonomer. A body having at least one terminal a functional group polymerizable with a (meth)acrylyl group.

Description

Curable resin composition, (meth)acrylic elastomer and sheet

The present invention relates to a curable resin composition, a (meth)acrylic elastomer, and sheets such as flexible sheets or stretchable sheets. Specifically, it relates to a sheet that can be used well as a protective film for Flexible Printed Circuits such as flexible printed circuit boards or circuit boards and wiring boards, and a curable resin composition used for producing the sheet, etc. and (meth)acrylic elastomers.

In recent years, the demand for sheets used in electronic components has increased. For example, as electronic products become lighter, smaller, and more dense, attention is also being paid to so-called Flexible Printed Circuits (hereinafter referred to as "FPC") called flexible printed circuit boards or flexible printed wiring boards. get taller. FPC is formed by using an insulating film as a base film (also called a substrate), laminating a metal foil via an adhesive layer, or forming a pattern made of conductive ink or film. A stretchable or flexible resin sheet made of various materials is used as a base film for such FPC (for example, Patent Document 1).

In addition, resin sheets can be used for various purposes such as protection of substrates for electronic components. For example, they are developed according to various uses and can be used for adhesive tapes or dielectric materials (for example, see Patent Documents 2 and 3). Furthermore, resin films for FPC are also being developed.

[Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2017-145325

[Patent Document 2] Japanese Patent Application Laid-Open No. 2014-105325

[Patent Document 3] Japanese Patent Application Publication No. 2017-132905

When resin sheets are used for FPC applications or protective applications, the material is required to be flexible in order to fully exhibit stretchability, and materials showing a low Young's modulus are being developed. However, resin films with excellent flexibility (low Young's modulus) generally have high viscosity and tend to be easily attached to other components. In this way, materials with high viscosity have poor handling properties, and improvements are required from the viewpoint of transportability in devices such as screen printing devices. On the other hand, low viscosity and low Young's modulus are opposite properties, and it is urgent to develop a material with a good balance of these properties.

In order to solve the above problems, an object of the present invention is to provide a curable resin composition capable of producing a (meth)acrylate elastomer that has both low viscosity and low Young's modulus in a well-balanced manner and a (meth)acrylate-based elastomer using the same. base) acrylic elastomers and sheets.

<1> A curable resin composition comprising: (meth)acrylic monomer; a cross-linking monomer having two or more functional groups polymerizable with (meth)acrylyl groups; and Macromonomer, which has a functional group polymerizable with (meth)acrylyl group at at least one end.

<2> The curable resin composition according to the above <1>, wherein the crosslinkable monomer is a (meth)acrylate compound having two or more (meth)acrylyl groups as the functional group.

<3> The curable resin composition according to the above <1> or <2>, wherein the macromonomer is at least one selected from the group consisting of styrene-based macromonomers and polyacrylate-based macromonomers.

<4> The curable resin composition according to any one of <1> to <3>, wherein the macromonomer has a (meth)acrylyl 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 the above <5>, wherein the acrylic monomer is at least one selected from the group consisting of 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 curable resin composition according to any one of the above <1> to <7>, which contains more than 0.25 to less than 5.0 mol% with respect to the total amount of the above (meth)acrylic monomers. The above-mentioned cross-linkable monomer.

<9> The curable resin composition according to any one of <1> to <8>, further containing a photopolymerization initiator.

<10> A (meth)acrylic elastomer obtained by polymerizing the curable resin composition according to any one of the above <1> to <9>.

<11> A sheet obtained by polymerizing the curable resin composition according to any one of the above <1> to <9>.

<12> The sheet as described in <11> above, which has been subjected to surface treatment noodle.

<13> The sheet according to the above <12>, wherein the surface treatment is blast processing.

<14> The sheet material according to any one of the above <11> to <13>, the arithmetic mean roughness Ra (nm) of at least one side is 50 to 300.

<15> The sheet according to any one of <11> to <14>, which is obtained by subjecting the curable resin composition to block polymerization.

According to the present invention, it is possible to provide a curable resin composition capable of producing a well-balanced (meth)acrylate elastomer having low viscosity and low Young’s modulus, and a (meth)acrylic resin composition using the same. Elastomers and sheets.

Figure 1 is a graph illustrating hysteresis loss and residual strain.

"Cure resin composition"

The curable resin composition of this embodiment contains: (meth)acrylic monomer; a crosslinkable monomer (hereinafter sometimes referred to as "Crosslinking monomer"); a macromonomer having a functional group polymerizable with a (meth)acrylyl group at at least one terminal (hereinafter, sometimes referred to as "macromonomer"). Furthermore, throughout this specification, "(meth)acrylic acid" means "acrylic acid" or "methacrylic acid", and "(meth)acrylate" means "acrylate" or "methacrylate". Also, in the case of abbreviated as "alkyl" When, it includes alkyl groups with straight chain, branched chain and alicyclic structures.

The curable resin composition of this embodiment includes a (meth)acrylic monomer, a crosslinkable monomer, and a macromonomer. By polymerizing each monomer component, it is possible to synthesize a well-balanced low viscosity and low Young's modulus of (meth)acrylic elastomer.

<(meth)acrylic monomer>

In this embodiment, the "(meth)acrylic monomer" is a monomer having one (meth)acrylyl group, and is distinguished from the crosslinkable monomer and macromonomer in this embodiment described later.

As the (meth)acrylic monomer in this embodiment, for example, a compound represented by the following formula (I) can be used.

(In the formula, R ¹ is a hydrogen atom or a methyl group; R ² represents an alkyl group with 1 to 10 carbon atoms that may have a hydroxyl group or a halogen atom, or an alkoxyalkyl group with 2 to 12 carbon atoms that may have a hydroxyl group)

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

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

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, iso-butyl, etc. Pentyl group, n-hexyl group, isohexyl group, cyclohexyl group, n-octyl group, etc. This embodiment is not limited only to these examples.

Examples of the alkyl group having 1 to 10 carbon atoms having a hydroxyl group include hydroxymethyl, hydroxyethyl, hydroxyn-propyl, hydroxyisopropyl, hydroxyn-butyl, hydroxyisobutyl, hydroxytert-butyl, etc. , this embodiment is not limited only to these examples.

Examples of the halogen atom contained in the alkyl group include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. 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. Therefore, it is preferably appropriately adjusted within a range that does not hinder the purpose of this embodiment.

Examples of the alkyl group having 1 to 10 carbon atoms having a halogen atom include trifluoromethyl, trifluoroethyl, trifluoro-n-propyl, trifluoroisopropyl, trifluoro-n-butyl, and trifluoroisobutyl. , trifluoro-tert-butyl, etc., this embodiment is not limited only to these examples.

Examples of the alkoxyalkyl group having 2 to 12 carbon atoms include alkoxy groups having 1 to 6 carbon atoms, such as methoxyethyl, ethoxyethyl, and methoxybutyl, and alkoxy groups having 1 to 6 carbon atoms. alkyl groups, alkoxyalkyl groups, etc., this embodiment is not limited only to these examples.

Examples of the alkoxyalkyl group having hydroxyl groups having 2 to 12 carbon atoms include hydroxymethoxyethyl. This embodiment is not limited to an alkoxyalkyl group having a hydroxyalkoxy group with 1 to 6 carbon atoms and an alkyl group with 1 to 6 carbon atoms, etc. in these examples.

From the viewpoint of the solubility of the macromonomer, R ² is preferably an alkyl group with 1 to 10 carbon atoms or an alkoxyalkyl group with 2 to 12 carbon atoms that does not have a hydroxyl or halogen atom. From the viewpoint of an elastomer with low Young's modulus and low hysteresis, an alkyl group having 1 to 4 carbon atoms or an alkoxyalkyl group having 1 to 4 carbon atoms is preferred, and an ethyl group and a methoxy group are more preferred. Ethyl.

Examples of the (meth)acrylic monomer represented by the formula (I) include: (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid n-propyl ester, (meth)acrylic acid Isopropyl ester, 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, n-octyl (meth)acrylate, nonyl (meth)acrylate, (meth)acrylic acid Cyclohexyl ester is equal to the (meth)acrylic monomer in formula (I) in which R ¹ is a hydrogen atom or a methyl group, and R ² is an alkyl group with 1 to 10 carbon atoms; (meth)hydroxypropyl acrylate, (meth)acrylic acid hydroxypropyl ester, Hydroxybutyl methacrylate is equal to the (meth)acrylic monomer in formula (I) in which R ¹ is a hydrogen atom or a methyl group, and R ² is an alkyl group with a carbon number of 1 to 10 having a hydroxyl group; acrylic acid 2, 2,2-Trifluoroethyl ester is equal to the (meth)acrylic monomer in formula (I) in which R ¹ is a hydrogen atom or a methyl group, and R ² is an alkyl group having 1 to 10 carbon atoms having a halogen atom; ( Methoxyethyl acrylate, ethoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate, phenoxyethyl acrylate, (2-methyl-2-ethyl acrylate) -1,3-Dioxolane-4-yl)methyl ester is equal to (methyl) in formula (I) in which R ¹ is a hydrogen atom or a methyl group, and R ² is an alkoxyalkyl group having 2 to 12 carbon atoms. ) Acrylic monomer; and diethylene glycol mono(meth)acrylate are equal to formula (I) in which R ¹ is a hydrogen atom or a methyl group, and R ² is an alkoxyalkyl with a hydroxyl group having 2 to 12 carbon atoms. based (meth)acrylic monomer.

Among them, as the (meth)acrylate elastomer in this embodiment, ethyl (meth)acrylate and methoxyethyl (meth)acrylate are more preferred, and an acrylic monomer is more preferred. More preferred are ethyl acrylate and methoxyethyl acrylate.

These (meth)acrylic monomers may be used individually, or two or more types may be used in combination.

<Cross-linkable monomer>

In this embodiment, the "crosslinkable monomer" means a monomer having two or more functional groups (hereinafter, sometimes simply referred to as "functional groups") that can be polymerized with (meth)acrylyl groups.

Examples of crosslinkable monomers include, for example, alkylene bis(meth)propylene having an alkylene group having 1 to 4 carbon atoms, such as methylene bisacrylamide and methylene bismethacrylamide. Amides and other (meth)acrylamide compounds having two or more, preferably two (meth)acrylamide groups as functional groups; ethylene glycol di(meth)acrylate, ethylene glycol di(methane) 1, 4-Butanediol di(meth)acrylate, 1,6-hexanediol di(meth)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, nonaethylene glycol di(meth)acrylate, etc. have 2 or more, preferably 2 or 3 ( (Meth)acrylate compounds with meth)acrylyl groups as functional groups; amines such as diallylamine and triallylamine having 2 or more, preferably 2 or 3 carbon-carbon double bonds as functional groups Compounds; polyfunctional monomers such as divinylbenzene, diallylbenzene and other aromatic compounds having two or more, preferably two or three carbon-carbon double bonds as functional groups.

Among them, as the cross-linkable monomer in this embodiment, from the viewpoint of obtaining an elastomer having low viscosity and low hysteresis, the cross-linkable monomer is preferably one having two or more (meth)acrylates. The acyl group is a (meth)acrylate compound of the above-mentioned functional group, and more preferably EGDMA, DEGDMA, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and even lower From the perspective of Young's modulus, EGDMA and DEGDMA are more preferred, and DEGDMA is particularly preferred.

However, the crosslinkable monomer in this embodiment is not limited to these examples. The cross-linkable monomers may be used individually, or two or more types may be used in combination.

<Giant unit>

"Macromonomer" is a molecule that functions as a monomer molecule and becomes a structural unit of the basic structure of a polymer. It is a polymer with a polymerizable group. The macromonomer in this embodiment has a functional group polymerizable with a (meth)acrylyl group at at least one terminal.

Examples of the "functional group polymerizable with a (meth)acrylyl group" possessed by the macromonomer in this embodiment include the functional groups possessed by the above-mentioned crosslinkable monomer.

The number average molecular weight of the macromonomer is not particularly limited, but from the viewpoint of low viscosity, it is preferably 1,000 or more, more preferably 2,500 or more, and particularly preferably 5,000 or more. The number average molecular weight of the macromonomer can be determined by gel permeation chromatography [manufactured by Tosoh Co., Ltd., product number: HLC-8320GPC, column: manufactured by Tosoh Co., Ltd., product number: Super H2500, solvent: tetrahydrofuran, Flow rate: 0.6 mL/min] Measured in polystyrene conversion.

The macromonomer in this embodiment is not particularly limited. From the viewpoint of low viscosity, examples include polystyrene-based macromonomers having an acryl group as a functional group at least at one terminal, preferably at one terminal. Monomer; polyacrylate-based macromonomer having at least one terminal, preferably both terminals, an acryl group as a cross-linkable group. As these macromonomers, those available as commercial products can be appropriately selected. For example, macromonomers manufactured by Toa Synthetic Chemical Co., Ltd. (for example, product name: AS-6 (polystyrene-based macromonomer) ), product name: AA-6 (polyacrylate macromonomer)), etc.

<Cureable resin composition>

The (meth)acrylic elastomer obtained by polymerizing the curable resin composition of this embodiment can have both low viscosity (low viscosity) and low Young's modulus.

The content rate of the (meth)acrylic monomer in the curable resin composition is not particularly limited. From the viewpoint of low hysteresis, it is preferably 75 to 92% by mass based on the total solid content, and more preferably It is 80~90% by mass, and the best one is 85~88% by mass.

The content rate of the crosslinkable monomer in the curable resin composition is not particularly limited. From the viewpoint of low Young's modulus and low hysteresis, it is preferably between 0.25 and less than the total amount of acrylic monomers. It is suitable to reach 5.0 mol%, more preferably 0.5~4.0 mol%, and particularly preferably 0.75~1.5 mol%.

The content rate of the macromonomer in the curable resin composition is not particularly limited, but from the viewpoint of low viscosity, it is preferably 6 to 15% by mass, and more preferably 7 to 12% by mass based on the total solid content. Mass%, particularly preferably 10~15 mass%.

The curable resin composition of this embodiment contains the above-mentioned (meth)acrylic monomer, crosslinkable monomer and macromonomer (hereinafter, these may be collectively referred to as "monomer components in this embodiment") That's it, but other ingredients can be included as needed.

(polymerization initiator)

In order to polymerize the monomer component in this embodiment, a curable resin composition can use a polymerization initiator. Examples of the polymerization initiator include photopolymerization initiators, thermal polymerization initiators, and the like. Among these polymerization initiators, a photopolymerization initiator is preferred from the viewpoint of not leaving a thermal history of the (meth)acrylic elastomer.

、2,4-雙(三氯甲基)-6-(對甲氧基苯基乙烯基)-1,3,5-三

、四氟硼酸二苯基錪、六氟磷酸二苯基錪、四氟硼酸4,4'-二第三丁基二苯基錪、六氟磷酸4-二乙基胺基苯基苯重氮鎓、安息香、2-羥基-2-甲基-1-苯基丙烷-2-酮、二苯甲酮、9-氧硫

、2,4,6-三甲基苯甲醯基二苯基醯基膦氧化物、三苯基丁基硼酸四乙基銨、二苯基-4-苯硫基苯基鋶六氟磷酸鹽、2,2-二甲氧基-1,2-二苯基乙烷-1-酮、苯基乙醛酸甲酯、2-甲基-1-[4-(甲硫基)苯基]-2-嗎啉基丙烷-1-酮、雙(2,4,6-三甲基苯甲醯基)-苯基膦氧化物、1-[4-(苯硫基)1,2-辛二酮-2-(鄰苯甲醯基肟)]、雙(η5-2,4-環戊二烯-1-基)雙[2,6-二氟-3-(1H-吡咯-1-基)苯基鈦]等光自由基聚合起始劑；2,4,6-三(三 氯甲基)-1,3,5-三

、2,4-雙(三氯甲基)-6-(對甲氧基苯基乙烯基)-1,3,5-三

、四氟硼酸二苯基錪、四氟硼酸4,4'-二第三丁基二苯基錪、六氟磷酸4-二乙基胺基苯基苯重氮鎓、二苯基-4-苯硫基苯基鋶六氟磷酸鹽等光陽離子開環聚合起始劑等；本實施形態並不僅限定於該等例示。該等光聚合起始劑可分別單獨使用，亦可併用2種以上。 Examples of the photopolymerization initiator include 2,4,6-trimethylbenzyldiphenylphosphine oxide and 2,2'-bis(o-chlorophenyl)-4,4',5, 5'-tetraphenyl-1,1'-biimidazole, 2,4,6-tris(trichloromethyl)-1,3,5-tris

, 2,4-bis(trichloromethyl)-6-(p-methoxyphenylvinyl)-1,3,5-tri

, diphenyl iodide tetrafluoroborate, diphenyl iodide hexafluorophosphate, 4,4'-di-tert-butyl diphenyl iodide tetrafluoroborate, 4-diethylamino phenyl benzene diazodiazide hexafluorophosphate Onium, benzoin, 2-hydroxy-2-methyl-1-phenylpropan-2-one, benzophenone, 9-oxosulfide

, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, triphenylbutylborate tetraethylammonium, diphenyl-4-phenylthiophenylsonium hexafluorophosphate , 2,2-dimethoxy-1,2-diphenylethan-1-one, methyl phenylglyoxylate, 2-methyl-1-[4-(methylthio)phenyl] -2-morpholinylpropan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 1-[4-(phenylthio)1,2-octyl dione-2-(o-benzoyl oxime)], bis(eta5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrole-1- base) phenyltitanium] and other photoradical polymerization initiators; 2,4,6-tris(trichloromethyl)-1,3,5-tris

, 2,4-bis(trichloromethyl)-6-(p-methoxyphenylvinyl)-1,3,5-tri

, diphenylphosphonium tetrafluoroborate, 4,4'-di-tert-butyldiphenylphosphonium tetrafluoroborate, 4-diethylaminophenylphenyldiazonium hexafluorophosphate, diphenyl-4- Photocationic ring-opening polymerization initiators such as phenylthiophenylsonium hexafluorophosphate, etc.; this embodiment is not limited only to these examples. These photopolymerization initiators may be used individually, or two or more types may be used in combination.

Examples of the thermal polymerization initiator include 2,2'-azobis(2-methylpropionate)dimethyl ester, 2,2'-azobisisobutyronitrile (AIBN), 2,2'- Azo polymerization initiators such as dimethyl azobisisobutyrate and azobisdimethylvaleronitrile, peroxide polymerization initiators such as benzoyl peroxide, potassium persulfate, and ammonium persulfate, etc. , this embodiment is not limited only to these examples. These polymerization initiators may be used individually, or two or more types may be used in combination.

The amount of the polymerization initiator cannot be determined uniformly depending on the type of the polymerization initiator. Generally, it is 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 this embodiment, a chain transfer agent may be used in order to adjust the molecular weight of the (meth)acrylic elastomer obtained. Examples of the chain transfer agent include compounds having a thiol group such as lauryl mercaptan, dodecyl mercaptan, and thioglycerol; inorganic salts such as sodium hypophosphite and sodium bisulfite; and the present embodiment is not limited thereto. Such examples. These chain transfer agents may be used individually, or two or more types may be used in combination. The amount of chain transfer agent varies depending on the type of chain transfer agent, so it cannot be determined uniformly. Generally, a similar amount is preferred. For every 100 parts by mass of monomer components, it is about 0.01 to 10 parts by mass.

(Other monomers)

The curable resin composition may contain monomer components other than the monomer components in this embodiment depending on required characteristics. Examples of other monomers include carboxyl group-containing monomers, carboxylic acid alkyl ester monomers other than the (meth)acrylic monomer represented by formula (I), amide group-containing monomers, This embodiment is not limited only to the examples of aryl group monomers, styrene-based monomers, nitrogen atom-containing monomers, fatty acid vinyl ester-based monomers, betaine monomers, etc. These monomers may be used individually, or two or more types may be used in combination.

"(meth)acrylic elastomer"

As described above, the (meth)acrylic elastomer obtained by polymerizing the curable resin composition of this embodiment can have both low viscosity (low viscosity) and low Young's modulus.

The glass transition temperature of the (meth)acryl elastomer is not particularly limited, but from the viewpoint of low viscosity and low Young's modulus, it is preferably -50°C or higher, and more preferably -20°C As mentioned above, the glass transition temperature of the (meth)acryl elastomer can be measured by the method described in the Examples described below.

Examples of methods for polymerizing the curable resin composition include block polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc., but this embodiment is not limited only to these examples. Among these polymerization methods, from the viewpoint of low viscosity, low Young's modulus, and low hysteresis, block polymerization and solution polymerization are preferred, and furthermore, from the viewpoint of low viscosity and low hysteresis, the block polymerization method and the solution polymerization method are preferred. words, more The best method is block polymerization. The (meth)acrylic elastomer of this embodiment can be easily produced when the monomer component of the raw material is polymerized not by the suspension polymerization method but by the block polymerization method like the conventional acrylic rubber. (Meth)acrylic elastomer with excellent elongation, low viscosity, and low hysteresis.

烷等。本實施形態並不僅限定於該等例示。該等有機溶劑可分別單獨使用，亦可併用2種以上。溶劑之量由於根據該溶劑之種類而不同，故而無法一概而定，通常，較佳為相對於單體成分每100質量份為100~1000質量份左右。 When polymerizing the curable resin composition by the solution polymerization method, a solvent is used. Among the solvents, non-aqueous organic solvents are preferred. Examples of non-aqueous organic solvents include hydrocarbon-based organic solvents such as hexane, heptane, octane, isooctane, decane, and liquid paraffin; ether-based organic solvents such as dimethyl ether, diethyl ether, and tetrahydrofuran; acetone, Ketones such as methyl ethyl ketone are organic solvents; esters such as methyl acetate, ethyl acetate, butyl acetate are organic solvents; chlorides such as dichloromethane, chloroform, carbon tetrachloride and other organic solvents; dimethylformyl Amine, diethyl formamide, dimethyl sulfoxide, dimethyl

Alkane etc. This embodiment is not limited only to these examples. These organic solvents may be used individually, or two or more types may be used in combination. Since the amount of the solvent varies depending on the type of the solvent, it cannot be determined uniformly. Generally, it is preferably about 100 to 1000 parts by mass per 100 parts by mass of the monomer component.

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

The temperature when polymerizing the curable resin composition is not particularly limited, but generally, a temperature of about 5 to 100° C. is preferred. The time required to polymerize the monomer components varies depending on the polymerization conditions and cannot be determined uniformly. Therefore, it is arbitrary, but is usually about 0.25 to 20 hours.

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

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

"Sheet"

The sheet of this embodiment can be obtained by polymerizing a curable resin composition. More specifically, the sheet can be produced using the above-mentioned (meth)acrylic elastomer. In this case, for example, the monomer component is cast on the substrate, and the formed coating of the monomer component is irradiated with ultraviolet rays to polymerize the monomer component, whereby a (meth)acrylic-based coating can be obtained. Elastomer film-like sheet.

That is, among the (meth)acrylic elastomers obtained by polymerizing the curable resin composition of the present embodiment, the wider one having a thickness below a certain level can be said to be the sheet of the present embodiment. Since the sheet of this embodiment is excellent in flexibility, expansion, and stretchability, it can be favorably used as a flexible sheet or an elastic sheet.

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

The sheet can be used as it is depending on the purpose. However, from the viewpoint of imparting strength and toughness, it is preferably uniaxially stretched or biaxially stretched, and more preferably biaxially stretched. From the viewpoint of imparting strength and 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 From the viewpoint of preventing breakage during stretching, it is preferably 8 times or less, more preferably 6 times or less, and even more preferably 5 times or less, but it varies depending on the thickness of the sheet. Furthermore, when stretching the sheet, heating may be performed if necessary.

The sheet of this embodiment may contain an appropriate amount of other polymers in order to adjust its viscosity.

Examples of other polymers include acrylic resin, polyacrylonitrile, poly(meth)acrylamide, polyamide, polyvinyl chloride, polyurethane, polyester, carboxymethyl cellulose, and the like. This embodiment is not limited only to these examples. These other polymers may be used individually, or two or more types may be used in combination.

The sheet of this embodiment may contain a neutralizing agent if necessary. Examples of the neutralizing agent include inorganic alkaline compounds such as sodium hydroxide and potassium hydroxide; monoethanolamine, dimethylethanolamine, diethylethanolamine, triethanolamine, morpholine, aminomethylpropanol, amine Organic basic compounds such as methylpropanediol, octylamine, tributylamine, and aniline; this embodiment is not limited only to these examples. These neutralizing agents may be used individually, or two or more types may be used in combination.

The sheet of this embodiment may contain additives within a range that does not hinder the purpose of this embodiment. Examples of additives include colorants, antioxidants, ultraviolet absorbers, anti-aging agents, thermally conductive fillers, conductive fillers, etc., but this embodiment is not limited only to these examples.

Furthermore, from the viewpoint of low viscosity, the sheet of this embodiment preferably has an Processed surface of surface treatment. The surface treatment is not particularly limited, and examples thereof include blast processing (concave-convex processing). Here, the so-called "blast processing" in this embodiment includes forming a film using a mold that has been blast processed, or using a film produced using the mold as a release film and forming a pattern on the release film. The concept of the appearance transferred to the surface of the sheet. For example, air or the like can be used to blow fine particles of sand into the mold cavity, imparting minimal damage, and then use the mold to transfer to the surface of the sheet. Furthermore, the pattern transferred to the surface of the sheet will be affected by surface tension or hardening shrinkage, and the surface roughness of the release film may not be transferred as it is.

Moreover, from the viewpoint of low viscosity, the arithmetic mean roughness (Ra) of at least one side of the sheet of the present embodiment is preferably 50 to 1000, more preferably 50 to 500, and particularly preferably 50 to 300. Examples of methods for measuring the arithmetic mean roughness include the methods described in the examples described below.

The Young's modulus, maximum point stress, and elongation (strain) of the sheet of this embodiment can be measured in accordance with JIS K 6251 using a tensile tester, for example.

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.

From the viewpoint of high elongation, the elongation rate of the sheet of this embodiment is preferably 50 to 2000%, more preferably 100 to 1000%, and particularly preferably 500 to 700%.

The hysteresis of the sheet of this embodiment can be measured by the method described in the Examples mentioned later. Specifically, hysteresis can be evaluated by measuring the "residual strain" or "hysteresis loss" of the sheet as an index.

The low compression permanent deformation of the sheet of this embodiment is preferably 10.0MPa‧% or less. The preferred value is 5.0MPa‧% or less, and the particularly preferred value is 3.0MPa‧% or less.

The residual strain of the sheet of this embodiment is preferably 10.0% or less, more preferably 5.0% or less, and particularly preferably 3.0% or less.

Since the sheet of this embodiment exhibits a good balance of low viscosity and low Young's modulus, it can be well used as a base film for FPC, a protective film for substrates for electronic components, medical materials, health care materials, and life products. Scientific materials, or robotic materials, etc.

[Example]

Next, this embodiment will be further described in detail based on examples. However, this embodiment is not limited only to these examples.

[Example 1]

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

The obtained curable resin composition was poured into a transparent glass forming mold (0.3 mm thick silicon spacer) attached with a blast-processed release film (arithmetic mean roughness (JIS B 0601): 430 nm). , can form a film with a length of 100mm, a width of 100mm, and a thickness of 0.3mm). Next, the curable resin composition was irradiated with ultraviolet rays at an irradiation dose of 0.20 mW/cm ² for 2 hours in a mold set in a water bath to cause bulk polymerization of the monomer components. Thereafter, the forming mold was taken out from the water bath, and the sheet containing the (meth)acrylic elastomer was taken out from the forming mold. Thereafter, the sheet was dried under conditions of 0.01 MPa or less and 80° C. for 3 hours, and each parameter described below was measured.

[Example 2]

A sheet was obtained in the same manner as in Example 1, except that a release film that had not been subjected to blast processing was used instead of a release film that had been subjected to blast processing.

[Comparative Examples 1~2]

A sheet was obtained in the same manner as in Examples 1 and 2 except that the crosslinkable monomer (diethylene glycol dimethacrylate) was not used.

[Comparative Examples 3~4]

A sheet was obtained in the same manner as in Examples 1 and 2 except that the macromonomer was not used.

[Comparative Examples 5~6]

A sheet was obtained in the same manner as in Examples 1 and 2 except that the crosslinkable monomer and macromonomer were not used.

"Evaluation"

The physical properties of the sheets of the examples and comparative examples were measured according to the methods shown below. The results are shown in Table 1.

[Arithmetic mean roughness (Ra)]

The arithmetic mean roughness of the sheet surface was determined for Examples 1 and 2 and Comparative Examples 3 and 4 by analyzing the image data obtained by the following scanning probe microscope. Specifically, the obtained image was tilt-corrected (the average value in the X direction and the average value in the Y direction), and after removing noise lines, the arithmetic mean roughness of the entire measurement range (20 μm square) was calculated. parse. In this measurement, the arithmetic mean roughness within the measurement range is expressed as a value exceeding the value represented as the lowest value and less than the value represented as the highest value. Each sheet was measured at 3 locations using the above measurement method. The lowest (highest) value among the 3 locations was used as the lowest and highest value for the sheet. The results are shown in Table 1.

[Use machine]

Scanning probe microscope: (Shimadzu Corporation, SPM-9700HT)

Cantilever: (manufactured by NanoWorld, NHCR-10)

Software used: Software originally included in SPM-9700HT

Measurement mode: dynamic mode

Scanning range: 20μm square

Scan speed: 0.1Hz

Number of pixels: 256×256

P gain: 0.001

I gain: 1500

Z range: ×1

[stickiness]

Place the sheet on a glass plate and use an electrical appliance to remove static electricity. Secondly, cover the screen printing plate (manufactured by SERIA Company, product name: 120424_for manual printing, mesh specification: SUS500 (calendered yarn thickness is 23 μm)) that has been used to remove static electricity from the top. Furthermore, the screen printing plate is pressed against the sheet using a scraper. When the screen printing plate is removed, even if part of it is attached to the screen printing plate and the sheet moves from its original position, it is judged that the sheet is attached to the screen printing plate. This determination was performed on the same sample 10 times, and the number of adhesion times was recorded. The smaller the adhesion number, the lower and better the viscosity is.

[Measurement of maximum point stress, elongation (strain), and 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 mounted so that the distance between the chucks of a tensile testing machine (manufactured by A&D Co., Ltd., product number: Tensilon RTG-1310) became 17 mm, and a tensile load was applied at a tensile speed of 50 mm/min until The operation of breaking the test piece is to measure the maximum point stress, elongation (strain) and Young's modulus.

[Measurement of hysteresis]

For hysteresis, hysteresis loss and residual strain are derived as evaluation indicators. Specifically, the following measurement was performed using the above-mentioned test piece and tensile testing machine, and the hysteresis loss and residual strain were calculated using the obtained graph.

The measurement is performed by applying a tensile load to the test piece until it reaches 100% elongation (making the distance between the chucks 34 mm) and the operation of returning the test piece that reaches 100% to 0% (the operation of returning the distance between the 34mm chucks to 17mm) (both at 50mm/min). This is one cycle and two cycles are performed. The hysteresis loss and residual strain are calculated from the graph of the measurement results of the second cycle.

The calculation method of hysteresis loss and residual strain will be explained in detail using Figure 1. Figure 1 is a graph illustrating hysteresis loss and residual strain.

The hysteresis loss is calculated by calculating the area surrounded by the dotted line (outward path) and the solid line (return path) in Figure 1. The smaller the hysteresis loss, the better the tracking performance.

The residual strain is as shown in Figure 1, using the line segment A from the ascending point (the point where the stress value is when the load is 0MPa on the forward path) to the maximum load and the return point (the stress value when the load is 0MPa is displayed on the return path). The difference from the point of the strain value at the maximum load to the line segment B of the maximum load is calculated by strain (residual strain) = (1-B/A) × 100.

As can be seen from Table 1, the sheet of Example 1 has a lower Young's modulus and a lower viscosity. again, The sheet material of Example 2 also had a tack measurement result of "5 times", indicating an acceptable level of tack.

On the other hand, the sheets of each comparative example showed tackiness above the allowable level.

[Example 3]

As the macromonomer, the same procedure as in Example 1 was used except that the same amount of polyacrylate macromonomer (manufactured by Toa Synthetic Chemical Co., Ltd., trade name: AA-6) was used instead of the polystyrene macromonomer. The sheets were made in the same way and evaluated in the same way.

As can be seen from the table, compared with Example 1 using a polystyrene-based macromonomer, the sheet using a polyacrylate-based macromonomer (polymethylmethacrylate-based macromonomer) has a lower Young's modulus and hysteresis. The result of slightly higher losses.

[Examples 4~6]

A sheet was produced in the same manner as in Example 1 except that the added amount of the macromonomer (relative to the total solid content in the composition) was changed as described in the table below, and the same evaluation was performed.

As can be seen from the table, the addition amount of the macromonomer increases and the viscosity becomes better. From the viewpoint of Young's modulus, hysteresis loss and residual strain, it is found that Examples 1 and 5 are excellent.

[Examples 7~9]

As the crosslinkable monomer, a sheet was produced in the same manner as in Example 1, except that the same amount of the crosslinkable monomer described in the following table was used instead of DEGDMA.

Each crosslinkable monomer described in the table is represented by the following (all manufactured by Shin-Nakamura Chemical Industry 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

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

[Examples 10~11]

A sheet was produced in the same manner as in Example 1 except that the added amount of the crosslinkable monomer (relative to the amount of ethyl acrylate) was changed to that shown in the table below, and the same evaluation was performed.

As can be seen from the table, all sheets are excellent in adhesion, but from the viewpoint of Young's modulus, the sheets of Example 1 and Example 10 are excellent.

[Examples 12~13]

As the (meth)acrylate monomer, use the same amount of (meth)acrylic acid listed in the table below. A sheet was produced in the same manner as in Example 1 except that the acrylic acid ester monomer was used instead of ethylene acrylate, and the same evaluation was performed.

Each (meth)acrylate monomer described in the table represents the following:

‧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, compared with the sheet of Example 13 using MEDOL-10, the sheets of Example 1 (using ethylene acrylate) and Example 12 (using methoxyethyl acrylate) have excellent adhesion.

The invention of Japanese Patent Application No. 2018-135076 filed on July 18, 2018 is hereby incorporated by reference in its entirety.

Furthermore, all documents, patent applications, and technical standards described in the specification are hereby incorporated by reference to the same extent as if each document, patent application, and technical standard were specifically and individually stated to be incorporated by reference. in the manual.

[Industrial availability]

The (meth)acrylic elastomer of the present invention can be favorably used as a base film for FPC, a protective film for electronic component substrates, medical materials, health care materials, life science materials, or robot materials.

Claims (12)

A curable resin composition comprising: (meth)acrylic monomer; a cross-linking monomer having two or more functional groups polymerizable with (meth)acrylyl groups; and a macromonomer, It has a functional group polymerizable with a (meth)acrylyl group at at least one terminal, wherein the content of the above-mentioned (meth)acrylic monomer is 75 to 92% by mass relative to the total solid content, and the above-mentioned cross-linkable monomer The content of the monomer is from more than 0.25 to less than 5.0 mol% relative to the total amount of the above-mentioned (meth)acrylic monomers, and the content of the above-mentioned macromonomer is 6-15% by mass relative to the total solid content. The above-mentioned macromonomer is The monomer is at least one selected from the group consisting of styrene-based macromonomers and polyacrylate-based macromonomers. The above-mentioned cross-linkable monomer does not include the above-mentioned macromonomers having more than two functional groups that can be polymerized with (meth)acrylyl groups. Single body. The curable resin composition according to claim 1, wherein the cross-linkable monomer is a (meth)acrylate compound having two or more (meth)acryl groups as the functional group. The curable resin composition according to claim 1 or 2, wherein the macromonomer has a (meth)acrylyl group as the functional group. The curable resin composition of claim 1 or 2, wherein the (meth)acrylic monomer is an acrylic monomer. The curable resin composition of claim 4, wherein the acrylic monomer is at least one selected from the group consisting of ethyl acrylate and methoxyethyl acrylate. The curable resin composition of claim 1 or 2, further comprising a photopolymerization initiator. A (meth)acrylic elastomer obtained by polymerizing the curable resin composition according to any one of claims 1 to 6. A sheet obtained by polymerizing the curable resin composition according to any one of claims 1 to 6. The sheet material of claim 8 has a processed surface that has been subjected to surface treatment. The sheet material of claim 9, wherein the above-mentioned surface treatment is blasting processing. For example, for the sheet of claim 8 or 9, the arithmetic mean roughness Ra (nm) of at least one side is 50~300. The sheet of claim 8 or 9 is obtained by subjecting the above-mentioned curable resin composition to block polymerization.