JP2015160927A - curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy ray-curable resin composition having a low dielectric constant and excellent transparency with suppressed white turbidity under a high humidity condition.SOLUTION: The energy ray-curable resin composition contains at a prescribed ratio, (A) polybutene and/or polyisobutylene having a number average molecular weight of 300 to 1500; (B) at least one selected from the group consisting of hydrogenated polybutadiene, hydrogenated polyisoprene, and polyisoprene each of which has an α,β-unsaturated carbonyl group; (C) a C6-20 alkyl or cycloalkyl (meth)acrylate; and fumed silica having a primary average particle diameter of 50 nm or less.

Description

  The present invention relates to a curable resin composition having a low dielectric constant and capable of providing a cured product excellent in transparency in which white turbidity due to moisture absorption is suppressed even in a high temperature and high humidity environment, and in particular, a capacitive touch panel. Suitable for large-sized image display devices such as car navigation systems, personal computer displays, televisions, and electronic blackboards equipped with a mobile phone, and small-sized image display devices equipped with capacitive touch panels such as portable terminals such as smartphones, tablet terminals, and media players The present invention relates to a curable resin composition that can be used in the present invention, a cured product of the curable resin composition, and an image display device that includes the cured product of the curable resin composition.

  In optical displays such as liquid crystal display devices and organic EL display devices, heat and chemical resistance are required for attaching protective sheets to display screens, bonding various functional optical sheets, and filling gaps between optical equipment members. In general, a curable resin composition having electrical properties such as insulation, adhesion, and transparency is used.

  A curable resin composition using a (meth) acryloyl group-containing polymer having a polymerizable functional group such as an acryloyl group or a methacryloyl group (collectively referred to as “(meth) acryloyl group” when these are not particularly distinguished) is cured. The reaction can be precisely controlled, and a cured product having excellent electrical properties such as heat resistance, chemical resistance, insulation, adhesion, and transparency can be obtained. It is generally known as an adhesive or filler used.

  In recent years, an adhesive having excellent resistance to white turbidity under humidified conditions has been demanded so that the screen of an image display device does not become clouded even under high humidity.

  As a cloud point-resistant adhesive that can be used for an optical display or the like, for example, in Japanese Translation of PCT International Publication No. 2012-503212 (Patent Document 1), 1 to 25 parts with respect to 100 parts of alkyl acrylate and a copolymerizable polar monomer. Compositions comprising these hydrophilic polymers have been proposed. Here, examples of the hydrophilic polymer include a polyethylene oxide segment, a hydroxyl functional group, or a combination thereof (paragraph 0020).

  In recent years, portable terminals such as a tablet type in which a touch panel is mounted on an image display device such as a liquid crystal display have become widespread, and among them, a capacitive touch panel has been widely used due to its functionality. With the demand for higher sensitivity for such tablet-type portable terminals, members used for capacitive touch panels are required to be low dielectric constant materials that do not affect the sensitivity at the time of input. ing.

  However, as described in Patent Document 1, in order to improve the turbidity resistance under humidified conditions, generally, a hydrophilic monomer or hydrophilic polymer containing a large amount of polar groups such as hydroxyl groups is used. . It has been confirmed that adhesives and fillers using compounds containing a large amount of polar groups tend to have a high dielectric constant. For this reason, studies have been made on adhesives and fillers that have a low dielectric constant and excellent white turbidity resistance under humidified conditions for display devices equipped with a capacitive touch panel.

  As an adhesive having a low dielectric constant and white turbidity under humidification, Japanese Patent Application Laid-Open No. 2012-173354 (Patent Document 2) has a relative dielectric constant of 4 or less at a frequency of 100 kHz and an environment of 95% RH. An optical pressure-sensitive adhesive sheet that can provide a pressure-sensitive adhesive layer having a moisture content of 0.65% by mass or more after storage for 120 hours has been proposed. Such an optical pressure-sensitive adhesive sheet includes an alkyl acrylate ester having a linear or branched alkyl group having 6 to 10 carbon atoms, and an alkyl methacrylate ester having a linear or branched alkyl group having 1 to 10 carbon atoms. An acrylic polymer composed of one or more monomer components selected from the group consisting of a (meth) acrylic acid ester having an alicyclic hydrocarbon group and a nitrogen-containing monomer, wherein the proportion of the monomer components is 60% by mass or more. An acrylic pressure-sensitive adhesive layer is included (claim 3).

Special table 2012-50312 gazette JP 2012-173354 A

  The specific permittivity of the pressure sensitive adhesive sheet specifically disclosed in the above-mentioned Patent Document 2 is 2.8 or more, and a large-sized image display device such as a television or personal computer display equipped with a capacitive touch panel, a tablet terminal. Further reduction in dielectric constant is required for adhesives and fillers used in small image display devices such as smartphones and smartphones.

  In addition, as an adhesive used in a display device such as a liquid crystal display device or an organic EL display device, at present, either an adhesive sheet of a type processed into a film or a sheet shape in advance or a fluid liquid type is used. . However, as a filler or adhesive used to improve the quality of the image by laminating a surface-shaped sheet or film having uneven unevenness, or filling a gap between optical members, it has fluidity. Liquid type is preferred.

  The present invention has been made in view of the circumstances as described above, and is a liquid adhesive that can be suitably used for adhesion between members of an image display device equipped with a capacitive touch panel, filling a gap, And it is providing the curable resin composition which can obtain the hardened | cured material excellent in transparency which is low dielectric constant and the white turbidity under high humidity is also suppressed.

  As a result of various investigations on liquid polymers that can achieve a low dielectric constant, the present inventors have found that polymers having a small number of polar groups, particularly polybutene and / or polyisobutylene, are effective in reducing the dielectric constant of an adhesive. . On the other hand, when used in combination with a (meth) acryloyl group-containing polymer or (meth) acryloyl group-containing monomer that is excellent in curability in order to impart curability, (meth) acryloyl group-containing is used due to compatibility issues. It turned out that transparency falls with the kind and content of a compound. In particular, when used in combination with a (meth) acryloyl group-containing polymer or a (meth) acryloyl group-containing monomer into which a polar group such as a hydroxyl group is considered effective for preventing white turbidity under humidification, a colorless and transparent cured product is obtained. It was found that it was difficult to achieve both low dielectric constant and low dielectric constant.

  The present inventors have further studied and can obtain a cured product having a low dielectric constant and a transparent cured product, and further capable of providing a cured product having excellent white turbidity resistance even under humidified conditions. The composition was completed.

That is, the curable resin composition of the present invention is
(A) 100 parts by mass of polybutene and / or polyisobutylene having a number average molecular weight of 300 to 1500;
(B) α, β-unsaturated carbonyl modification (hydrogenation) which is at least one selected from the group consisting of hydrogenated polybutadiene, hydrogenated polyisoprene, and polyisoprene having an α, β-unsaturated carbonyl group. 5 to 50 parts by mass of a conjugated diene polymer;
(C) 2 to 30 parts by mass of an alkyl or cycloalkyl ester having 6 to 20 carbon atoms of (meth) acrylic acid; and (D) 0.5 to 10 parts by mass of fumed silica having a primary average particle size of 50 nm or less. To do.

  The pour point of the (A) polybutene and / or polyisobutylene is preferably 0 ° C. or lower.

  The (B) α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer is a (meth) acryloyl-modified hydrogenated polybutadiene having a urethane bond, a (meth) acryloyl-modified hydrogenated polyisoprene having a urethane bond, and It is preferably at least one selected from the group consisting of (meth) acryloyl-modified polyisoprene having a urethane bond. Alternatively, hydrogenated polybutadiene, hydrogenated polyisoprene, or polyisoprene having a α, β-unsaturated carbonyl group in the side chain thereof may be used.

  The (B) α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer is the (B) α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer. And / or a product obtained by an α, β-unsaturated carbonyl modification reaction in the presence of a polyisobutylene solvent.

  The curable resin composition of the present invention may further contain (E) a photopolymerization initiator. Moreover, it is preferable that the dielectric constant of the hardened | cured material obtained by hardening a curable resin composition is less than 2.8.

  The present invention also includes a cured product obtained by curing the curable resin composition of the present invention by energy ray irradiation. Moreover, the image display apparatus which has the said hardened | cured material is also included.

  The curable resin composition of the present invention can satisfy both requirements of low dielectric constant and suppression of white turbidity under high-humidity conditions, and is liquid at room temperature, even on uneven adherends. Can be filled without gaps.

  The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not limited to these contents.

<Energy beam curable resin composition>
The curable resin composition of the present invention comprises (A) 100 parts by mass of polybutene and / or polyisobutylene having a number average molecular weight of 300 to 1500;
(B) At least one α, β-unsaturated carbonyl-modified (hydrogenated) conjugate selected from the group consisting of hydrogenated polybutadiene, hydrogenated polyisoprene, and polyisoprene having an α, β-unsaturated carbonyl group. 5 to 50 parts by mass of a diene polymer;
(C) 2 to 30 parts by mass of an alkyl or cycloalkyl ester having 6 to 20 carbon atoms of (meth) acrylic acid; and (D) a fumed silica having a primary average particle diameter of 50 nm or less (Fumed silica) 0.5 to Contains 10 parts by weight.
Hereinafter, each component will be described.

(A) Polybutene and / or polyisobutylene Polybutene is obtained by copolymerizing 1-butene and 2-butene mainly with isobutylene, and polyisobutylene is a homopolymer of isobutylene. These are commercially available in molecular weights ranging from liquid to solid at room temperature depending on molecular weight, but polybutene and polyisobutylene used in the present invention are low molecular weight types having a number average molecular weight of 300 to 1500.

  If the number average molecular weight is 300 or less, it may be separated from the cured product over time after curing and cause bleed out. If the number average molecular weight is 1500 or more, the fluidity of the composition decreases, When workability is lowered and it is used as a filler, voids are easily generated, which is not preferable. On the other hand, since polybutene and polyisobutylene having a number average molecular weight of 300 to 1500 are liquid at normal temperature, it is possible to provide a liquid composition without diluting the composition with a solvent or the like. Moreover, since it is liquid at normal temperature, it can be used as a solvent when the component (B) is synthesized. The product synthesized in the presence of the component (A) solvent can be used as it is as the component (B) without performing an isolation operation.

  The polybutene and / or polyisobutylene having the above molecular weight range is liquid at room temperature, but preferably has a pour point of 0 ° C. or lower.

  As such polybutene, a commercially available product can be used. For example, Nisseki Polybutene LV-7, Nisseki Polybutene LV-10, Nisseki Polybutene LV-25, Nisseki Polybutene LV manufactured by JX Nippon Oil & Energy Corporation. -50, Nisseki polybutene LV-100, Nisseki polybutene HV-15, Nisseki polybutene HV-35, Nisseki polybutene HV-50, Nisseki polybutene HV-100, Nisseki polybutene HV-300; Indopol manufactured by ENEOS L-8, Indopol L-14, Indopol H-7, Indopol H-15, Indopol H-25, Indopol H-25, Indopol H-50, Indopol H-100, Indopol H-300 and the like. Examples of commercially available products of polyisobutylene include TPC595, TPC1105 manufactured by Texas Petrochemicals; Glossopal 1000, Gissopal 1300, Gissopal V190, Gissopal V500, Glossopal V640 manufactured by BASF.

  Polybutene and polyisobutylene do not have a polar group in the molecular chain, and contribute to lowering the dielectric constant of the composition and cured product. Polybutene and polyisobutylene may be used alone or in combination. The content of the polybutene and / or polyisobutylene in the composition is preferably 60% by mass or more, more preferably 70% by mass or more, based on the total amount of the polybutene and polyisobutylene.

(B) α, β-Unsaturated carbonyl-modified hydrogenated polybutadiene, α, β-unsaturated carbonyl-modified polyisoprene, or α, β-unsaturated carbonyl-modified hydrogenated polyisoprene B component imparts curability to the composition At least one selected from the group consisting of α, β-unsaturated carbonyl-modified hydrogenated polybutadiene, α, β-unsaturated carbonyl-modified polyisoprene, and α, β-unsaturated carbonyl-modified hydrogenated polyisoprene. It is.

  The B component is excellent in compatibility with the A component polybutene and / or polyisobutylene, and can impart curability and adhesion without impairing transparency.

  Here, α, β-unsaturated carbonyl-modified hydrogenated polybutadiene, α, β-unsaturated carbonyl-modified polyisoprene, and α, β-unsaturated carbonyl-modified hydrogenated polyisoprene are hydrogenated polybutadiene, polyisoprene, hydrogenated. It is a compound having an α, β-unsaturated carbonyl group at the molecular chain end or side chain of polyisoprene (hereinafter sometimes collectively referred to as “(hydrogenated) conjugated diene polymer”). is there.

  Hydrogenated polybutadiene is obtained by hydrogenating polybutadiene synthesized by 1,2-addition polymerization and / or 1,4-addition polymerization of butadiene. The hydrogenation may be a partial hydrogenation product as long as the compatibility with the component A and the transparency of the cured product are not impaired. In addition, Formula (1) has shown the hydrogenated polybutadiene (completely hydrogenated product) mentioned as an example. (1) In the formula, p and q are each an integer of 0 to 100, and p + q = an integer of 10 to 150.

  Polyisoprene is obtained by addition polymerization of isoprene, and may be any of 1,4-addition polymer, 1,2-addition polymer, and 3,4-addition polymer. In the case of 1,4-addition polymer, It may be a cis isomer or a trans isomer. Polyisoprene may or may not be hydrogenated. When hydrogenated, polyisoprene may be either fully hydrogenated or partially hydrogenated.

  Further, in the present invention, as shown in the following formula (2), a multimeric α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer unit is connected via a connecting part. , Β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymers can also be used.

  (2) In the formula, the linking part is an organic group having a urethane bond, an ester bond or an ether bond at both ends, and preferably both ends of the hydrocarbon chain which may have 1 to 10 carbon atoms are branched. This is the case of binding.

  Such α, β-unsaturated carbonyl-modified hydrogenated polybutadiene, α, β-unsaturated carbonyl-modified polyisoprene, α, β-unsaturated carbonyl-modified hydrogenated polyisoprene (hereinafter referred to as “α , Β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer ”may be a commercially available product or may be synthesized.

  Commercially available products of α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymers include, for example, TEAI-1000 (produced by Nippon Soda Co., Ltd.), SPBDA (Osaka Organic Chemical Co., Ltd.), a hydrogenated polybutadiene containing (meth) acryloyl groups. UC-102, UC-203 (manufactured by Kuraray Co., Ltd.), polyisoprene containing (meth) acryloyl group, GI-1000, GI-2000, GI-3000 (hydrogenated polybutadiene diol) (Nippon Soda Co., Ltd.) Product) and (meth) acryloyl group-containing monoisocyanate, polyisoprene diol Poly ip (manufactured by Idemitsu Kosan Co., Ltd.) and (meth) acryloyl group-containing monoisocyanate, polyisoprene diol Epol ( Reaction between Idemitsu Kosan Co., Ltd.) and (meth) acryloyl group-containing monoisocyanates Such as are preferably used.

  Synthetic products include, for example, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene hydroxylated (hydrogenated) conjugated diene polymer polyol, and α, β- having functional groups capable of reacting with hydroxyl groups. It can be synthesized by reaction with an unsaturated carbonyl compound.

  Examples of the α, β-unsaturated carbonyl compound having a functional group that reacts with a hydroxyl group include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, tiglic acid and angelic acid; 2-acryloyloxyethyl isocyanate, 2- An α, β-unsaturated carbonyl group-containing isocyanate compound such as methacryloyloxyethyl isocyanate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate can be used.

  When the above α, β-unsaturated carbonyl compound is reacted with a (hydrogenated) conjugated diene polymer polyol (hydrogenated polybutadiene polyol, polyisoprene polyol, or hydrogenated polyisoprene polyol), (hydrogenated) conjugate is obtained. A compound in which a (meth) acryloyl group is introduced into a diene polymer via an ester bond, a urethane bond, or an ether bond is obtained.

  In the case of a multimeric α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer represented by the formula (2), for example, the above α, β-unsaturated carbonyl compound and a simple substance (hydrogenated) It is obtained by reacting a conjugated diene polymer polyol with a linking compound having at least one selected from the group consisting of an isocyanate group, a carboxyl group, a carbonyl halide group, an epoxy ring, and a hydroxyl group.

  Α, β-carbonyl-modified (hydrogenated) conjugated diene polymer in which a (meth) acryloyl group is introduced via an ester bond, urethane bond, or ether bond, and such α, β-carbonyl-modified (hydrogenated) conjugate The method for synthesizing the multimeric unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer having a plurality of diene polymer units is not particularly limited. For example, the polymer can be synthesized by the method described in Japanese Patent Application No. 2013-069121. .

  In the case of an α, β-unsaturated carbonyl modified (hydrogenated) conjugated diene polymer in which the side chain of the (hydrogenated) conjugated diene polymer is α, β-unsaturated carbonyl modified, for example, the corresponding conjugated diene polymer Can be synthesized by, for example, reacting a side chain succinic anhydride group obtained by reaction with maleic anhydride and a hydroxyl group-containing α, β-unsaturated carbonyl compound. In addition, when introducing a succinic anhydride group to a (hydrogenated) conjugated diene polymer, it is preferable to first hydrogenate after reacting maleic anhydride.

  (Hydrogenated) The reaction for introducing an α, β-unsaturated carbonyl group into a conjugated diene polymer (α, β-unsaturated carbonyl modification reaction) is usually performed in the presence of a solvent. In the composition of the present invention, the A component (polybutene, polyisobutylene) can be used as a reaction solvent since the polybutene and polyisobutylene as the A component are liquid at room temperature. The product obtained by the synthesis can be used as a mixture of the component (A) and the component (B) without an operation such as solvent removal. This has an advantage that not only simplification of the process of solvent removal operation but also contamination of impurities such as residual solvent derived from component B can be avoided in the composition. Since the residual solvent can cause voids in the cured product, avoiding the use of the B component in which the solvent other than the essential components of the composition remains, in turn, makes the adhesive layer transparent and improves image quality. The effect can be expected.

  The number average molecular weight and viscosity of the resulting unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer vary depending on the type of conjugated diene used as a repeating unit, the presence or absence of multimerization, etc., but generally the molecular weight and viscosity are reduced by multimerization. As the number of conjugated diene polymer segments increases, the molecular weight and viscosity further increase.

  Specifically, the number average molecular weight of the unitary unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer is usually 500 to 50,000, although it depends on the type of (hydrogenated) conjugated diene that is a repeating unit. Is 1000-40000, more preferably 1500-35000. The viscosity at 25 ° C. is 3 to 1000 Pa · s, preferably 20 to 800 Pa · s, although it varies depending on the type of hydrogenated conjugated diene serving as a repeating unit, reaction conditions, and the like.

  The number average molecular weight of the multimeric unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer depends on the type of (hydrogenated) conjugated diene that is a repeating unit and the number of linkages of the (hydrogenated) conjugated diene polymer. By dimerization and trimerization, it becomes 1000 to 60000, preferably 3000 to 50000, more preferably 5000 to 40000, and still more preferably 8000 to 30000. Further, the viscosity at 25 ° C. is 10 to 2000 Pa · s, although it varies depending on the kind of (hydrogenated) conjugated diene serving as a repeating unit, reaction conditions and the like.

  In addition, the number average molecular weight as used in this specification is the value measured using the gel permeation chromatography (solvent: tetrahydrofuran). The viscosity can be measured using a B-type viscometer (model “RB80L” manufactured by Toki Sangyo Co., Ltd.) under a temperature of 25 ° C.

  The α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer used as the component (B) in the present invention is an α having two or more α, β-unsaturated carbonyl groups per polymer molecular chain. , Β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer, and α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene having only one α, β-unsaturated carbonyl group per polymer chain It may be a mixture with a polymer. The α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer as a whole preferably has an average of 1.5 or more α, β-unsaturated carbonyl groups per polymer molecular chain.

  The α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer as described above is excellent in compatibility with the component A and imparts curability to the composition without impairing the effect of reducing the dielectric constant by the component A. can do. The α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer is blended at a ratio of 5 to 50 parts by mass with respect to 100 parts by mass of the component (A). If it is 5 parts by mass or less, polybutene and polyisobutylene are easily separated over time or at high temperatures. On the other hand, when the amount is 50 parts by mass or more, the ratio of the A component in the cured product is relatively decreased, so that the reduction of the dielectric constant is insufficient. The compounding quantity of B component becomes like this. Preferably it is 8-40 mass parts, More preferably, it is 10-30 mass parts.

(C) C6-C20 alkyl or cycloalkyl ester of (meth) acrylic acid (C) C6-C20 alkyl or cycloalkyl ester of (meth) acrylic acid is (B) α, β-unsaturated It is used as a polymerizable compound capable of co-curing with a carbonyl-modified (hydrogenated) conjugated diene polymer.

  A (meth) acrylate compound having less than 6 carbon atoms has a high dielectric constant, and a (meth) acrylate compound having more than 20 carbon atoms has a high viscosity of the curable resin composition, which is not preferable. . Of these, a cycloalkyl ester of (meth) acrylic acid is particularly preferable because the dielectric constant can be kept low.

  As a C6-C20 alkyl or cycloalkyl ester of (meth) acrylic acid, for example, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl ( C6-C20 alkyl group-containing (meth) acrylates such as meth) acrylate; cyclohexyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, norbornanyl (meth) acrylate, dicyclopentenyl (meth) ) Acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate Such cycloalkyl group-containing (meth) acrylate are preferably used.

  (C) The compounding ratio of the alkyl or cycloalkyl ester having 6 to 20 carbon atoms of (meth) acrylic acid is 2 to 30 parts by mass with respect to 100 parts by mass of (A) polybutene or polyisobutylene. If it is 2 parts by mass or less, the viscosity of the composition becomes high, and if it is 30 parts by mass or more, the dielectric constant of the cured adhesive becomes high. More preferably, it is 2-20 mass parts, More preferably, it is 3-15 mass parts.

In the curable resin composition of the present invention, the polymerizable compound that can be co-cured with the α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer (B) is within a range that does not impair the effects of the present invention. If it is, you may use together polymerizable compounds other than the C6-C20 alkyl or cycloalkyl ester of (meth) acrylic acid.
Examples of other polymerizable compounds that can be used in combination include (meth) acrylates having less than 6 carbon atoms described in paragraph 0095 of JP2013-014718; methyl-2-allyloxymethyl acrylate, 2-hydroxylpropyl acrylate, and the like. (Meth) acrylates having a substituent other than the alkyl group or cycloalkyl group; vinyl monomers described in paragraph 0096 of JP2013-014718A, and the like.
However, it is preferable that an unsaturated compound containing a hydroxyl group (for example, hydroxyl acrylate) or the like generally used for the purpose of imparting hydrophilicity to the cured product is not included from the viewpoint of dielectric constant.

(D) Fumed silica The fumed silica used in the present invention is a compound having a primary particle diameter of 50 nm or less mainly composed of silicon oxide. Fumed silica has a silanol group on the particle surface, a hydrophobic type in which a part of the silanol group is modified with an organic group, and a hydrophilic type in which the silanol group remains unmodified. Any type can be used, but it can effectively suppress the white turbidity of the adhesive particularly under high humidity, and it can effectively suppress the temporal separation of polybutene and polyisobutylene from the cured product even at high temperatures. A hydrophilic type is preferably used.

  Commercially available products can be used as the fumed silica. For example, as the hydrophilic type, AEROSIL 90, AEROSIL 130, AEROSIL 150, AEROSIL 200, AEROSIL 255, AEROSIL 300, AEROSIL 380 manufactured by Evonik Industries, Inc., CABOT CAB-O-SIL LM-150, CAB-O-SIL M5, CAB-O-SIL H5, CAB-O-SIL EH5; WACKER HDK S13, WACKER HDK V15, WACKER HDK N20, WACKER HDK manufactured by WACKER T30, WACKER HDK T40, etc. can be used. In addition, as the hydrophobic type, AEROSIL R972, AEROSIL R974, AEROSIL R104, AEROSIL R202, AEROSIL R805, AEROSIL R812, AEROSIL R816 manufactured by Evonik Industries, Inc. Use CAB-O-SIL TS-710, CAB-O-SIL TS-610, CAB-O-SIL TS-530; WACKER HDK H15, WACKER HDK H18, WACKER HDK H20, WACKER HDK H30, etc. manufactured by WACKER Can do.

  The fumed silica as described above has a role of suppressing white turbidity of the cured product under humidified conditions. Although the mechanism that can suppress white turbidity under high humidity by blending fumed silica is unclear, it seems to be because water droplets can be prevented from being produced in the cured product. In addition, the formation of a network by silanol groups is considered to be useful for maintaining the shape of the cured product at a high temperature. Due to the characteristics of fumed silica, it is possible to achieve both reduction in dielectric constant and prevention of white turbidity, which has been difficult with polar group-containing polymers or polar group-containing compounds.

  The compounding ratio of such fumed silica is 0.5 to 10 parts by mass with respect to 100 parts by mass of the total amount of (A) polybutene and polyisobutylene. If it is 0.5 parts by mass or less, the white turbidity of the cured product at the time of humidification becomes insufficient, and it becomes easy to separate from polybutene and polyisobutylene over time at the time of curing and at a high temperature. On the other hand, when 10 parts by mass or more is blended, the dielectric constant of the cured product is increased, which is not preferable. From the point which makes low dielectric constant of hardened | cured material and white turbidity suppression at the time of moisture absorption compatible, Preferably it is 1-8 mass parts, More preferably, it is 1.5-6 mass parts.

(E) Photopolymerization initiator The curable resin composition of the present invention may further contain (E) a photopolymerization initiator in addition to the components (A), (B), (C), and (D). preferable. Thereby, it becomes possible to harden a composition by energy ray irradiation for a short time.

  As the photopolymerization initiator, a photopolymerization initiator conventionally used in the field of energy beam curable resin compositions can be used. Examples include photopolymerization initiators described in paragraphs 0089 and 0090 of JP2013-014718A. Among them, acetophenones, oxy-phenyl-acetic acid 2- [2-oxo-2-phenyl-acetoxy- Ethoxy] ethyl ester, oxy-phenyl-acetic acid 2- [2-hydroxy-ethoxy] ethyl ester, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl- Diphenyl-phosphine oxide and the like are preferable.

  As content of the photoinitiator in an adhesive resin composition, although it changes with uses, it is suitable that it is 0.1-10 mass% normally with respect to 100 mass% of the said resin compositions. When the content is 0.1% by mass or more, the resin composition can be sufficiently cured, and when the content is 10% by mass or less, generation of odor and coloring of the cured product can be sufficiently suppressed. More preferably, it is 0.3-5 mass%, More preferably, it is 0.3-3 mass%.

(F) Other components In addition to the above components, the adhesive composition of the present invention can contain (A) polybutene and / or, if necessary, within a range that does not impair the effects of the present invention, particularly the dielectric constant reduction effect. Alternatively, non-reactive resins other than polyisobutylene and (B) α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer may be included.

  Other non-reactive resins that can be used in the present invention include polyethylene glycol, polypropylene glycol, polyether polyols such as ethylene oxide and propylene oxide copolymers; polyolefin resins such as polyethylene, polypropylene, and polystyrene; polymethyl methacrylate, poly (Meth) acrylic polymer having no polymerizable functional group or double bond in the side chain such as acrylic acid; polyester resin such as polyethylene terephthalate; polyamide resin such as nylon 6 and 6; hydrogenated or non-aqueous Conjugated diene polymers other than hydrogenated polyisoprene and hydrogenated polybutadiene; thermoplastic elastomers, terpene resins, terpene phenol resins, modified terpene resins, hydrogenated terpene resins, rosin ester resins, and the like.

  Moreover, you may contain a plasticizer other than the said component as needed. The plasticizer is a conventionally known plasticizer, for example, a compound having no (meth) acryloyl group, and examples thereof include the plasticizers described in paragraphs 0091 and 0092 of JP2013-014718A.

  Furthermore, as long as the effects of the present invention are not impaired as required, thermosetting catalyst, ultraviolet absorber, chain transfer stabilizer, light stabilizer, polymerization inhibitor, antioxidant, leveling agent, thickener, You may include a viscosity reducing agent, a thixotropy imparting agent, a defoaming agent, a coloring agent, etc.

  For example, each compound described in paragraphs 0078 to 0082 of JP2012-162705A can be used.

  Examples of the antioxidant include commercially available ADK STAB AO-10 to AO-80, ANTAGE W-300, W-400, and W-500. AO-50 and AO-60 are preferably used from the viewpoint of durability.

  The other components as described above are appropriately selected depending on the use of the resin composition, but are usually preferably 0 to 40% by mass, more preferably 0 to 20% by mass, and particularly preferably 0 to 10% by mass. %.

  In addition, it is preferable that the content rate of (A) polybutene and / or polyisobutylene which concerns on this invention shall be 60 mass% or more of the whole resin composition. When the content of the A component is too low, the effect of reducing the dielectric constant is reduced.

[Method for preparing curable composition]
The curable composition of this invention should just mix the above components in a predetermined ratio. Since component A is liquid at room temperature, other components can be added and mixed using component A as a solvent. In particular, the synthesis of component B, that is, the reaction of hydrogenated polybutadiene, polyisoprene, or hydrogenated polyisoprene with an α, β-unsaturated carbonyl compound in the presence of a solvent comprising component A, A predetermined proportion of the mixture with the component B can be obtained. A predetermined amount of C component and D component may be added and mixed with the mixture.

  For the addition and mixing of fumed silica, it is preferable to use a stirrer such as a homomixer to stir the mixture so as to be homogeneous.

[Curing method of curable composition]
The curable composition of the present invention can be applied to a predetermined site by a method such as coating, dropping filling, or pouring. What is necessary is just to select suitably according to the property of a composition, a viscosity, and an application location.

  The curable composition of the present invention having the above composition comprises (C) an alkyl or cycloalkyl ester of 6 to 20 carbon atoms of (meth) acrylic acid, and (B) a carbonyl-modified (hydrogenated) conjugated diene system. It can be cured by a polymerization reaction of the polymer. The curing reaction can be initiated by heat, light, or irradiation with various energy rays. Photocuring is preferable from the viewpoint of curing speed and workability. It is possible to use both curing by light irradiation and curing by heating.

As the energy rays, electron beams, radiation, ultraviolet rays, and the like can be used, and ultraviolet rays having a wavelength of 150 to 450 nm are preferable. Examples of light sources that emit such wavelengths include solar rays, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, gallium lamps, xenon lamps, flash type xenon lamps, carbon arc lamps, and LED type UV light sources. It is done. Irradiation integrated light quantity is preferably 0.1~10J / cm ^2, more preferably 0.2~5J / cm ^2, more preferably in the range of 0.3~3J / cm ^2.

  In the case of thermosetting, infrared rays, far infrared rays, hot air, high frequency heating or the like may be used. The heating temperature may be appropriately adjusted according to the decomposition temperature of the thermosetting catalyst, the type of base material used, and the like, and is not particularly limited, but is preferably 50 to 150 ° C, more preferably 50 to 100 ° C. More preferably, it exists in the range of 60-90 degreeC. The heating time may be appropriately adjusted according to the decomposition temperature or coating thickness of the thermosetting catalyst, and is not particularly limited, but is preferably 1 minute to 12 hours, more preferably 10 minutes to 6 hours, Preferably, it is within the range of 10 minutes to 3 hours.

  Furthermore, you may obtain by using together hardening by electron beam irradiation with hardening by light irradiation. In this case, the acceleration voltage is preferably 0 to 500 kV, more preferably 20 to 300 kV, and even more preferably 30 to 200 kV. The irradiation amount is preferably in the range of 2 to 500 kGy, more preferably 3 to 300 kGy, and still more preferably 4 to 200 kGy.

  The curable resin composition is cured by the curing reaction as described above. The term “curing” as used herein means a state having no fluidity, and is a state in which the shape can be maintained. The component A is liquid at room temperature and does not participate in the curing reaction, but a cured product can be obtained with the composition of the present invention. Although the detailed curing mechanism is unknown, since the A component and the B component are excellent in compatibility, the A component can be finely dispersed in the composition, cured in such a state, and a network structure obtained by curing. It is presumed that the bleed-out from the cured product is prevented by being confined inside.

  Therefore, the curable resin composition of the present invention has a low dielectric constant, although it depends on the content ratio of the components (A) to (D), the composition and type of the unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer, A cured product that is excellent in heat resistance, light resistance and moisture resistance and can maintain transparency even at high humidity can be provided.

<Use of resin composition>
Since the cured product of the resin composition of the present invention has a low dielectric constant and excellent transparency, it goes without saying that it has a conventionally known use such as an adhesive and a filler between optical display members, and is particularly transparent. For example, it can be suitably used as an adhesive between a transparent glass plate of a capacitive touch panel and a display, a protective sheet or the like, or a filler for a gap.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to description of a following example.
In the examples, “part” means mass basis unless otherwise specified.

<Measurement and evaluation method>
The evaluation methods employed in this example are as follows.
〔Evaluation method〕
(1) Number average molecular weight (Mn)
Using Tosoh columns TSK-gel SuperHM-H and TSK-gel SuperH2000, using Tosoh gel permeation under conditions where the temperature is 40 ° C. and the flow rate is 0.3 mL / min. It is a value obtained by chromatography (GPC) apparatus HLC-8220GPC and converted to standard polystyrene.

(2) Composition viscosity (mPa · s)
The viscosity of the obtained resin composition was measured using an R / S Rheometer (manufactured by BROOKFIELD, cone plate C50-2) under the condition of a temperature of 25 ° C., and the value at 1 rpm was taken as the measured value.

(3) Curability (J / cm ² )
The obtained resin composition is coated on a glass plate so as to have a thickness of 4 mm, and irradiated with UV light by an LED type UV irradiator at 1 J / cm ² (value at 385 nm) to obtain a hardness value. The light irradiation amount (385 nm) at which becomes constant was measured.

(4) Turbidity About the test piece (width 25 mm x length 25 mm x resin thickness 4 mm) in a state where the obtained resin composition is cured and sandwiched between glass plates (thickness 1 mm), the degree of turbidity is confirmed visually. Evaluation was made in the following three stages.
○: Transparent (no turbidity)
Δ: Slightly cloudy ×: Cloudy

(5) Light transmittance (%)
For a test piece (width 50 mm × length 70 mm × thickness 0.3 mm) in a state where the obtained resin composition is cured and sandwiched between glass plates (thickness 1 mm), the light transmittance at 400 nm is measured with a spectrophotometer (type “ UV-3100 ", manufactured by Shimadzu Corporation).

(6) Relative permittivity ε (100 kHz)
A sheet-like test piece (width 50 mm × length 50 mm × thickness 1 mm) formed by curing the obtained resin composition is sandwiched between electrodes (Solartron SH2-Z, electrode diameter 10 mm), and impedance analyzer (Solartron) In S1-1260), the capacitance was measured, and the relative dielectric constant was calculated.

(7) Heat resistance A test piece (width 50 mm × length 70 mm × thickness 0.5 mm) in which the obtained resin composition is cured and sandwiched between glass plates (thickness 1 mm) is prepared in an oven at 100 ° C. For a predetermined time. The shape retention property of the test piece after heating was confirmed visually and evaluated in the following three stages.
◯: No change in shape Δ: Slight change in shape ×: Significant change in shape

(8) Moisture resistance The obtained resin composition is cured and a test piece (width 50 mm × length 70 mm × thickness 0.3 mm) in a state of being sandwiched between glass plates (thickness 1 mm) is produced in a thermostatic chamber. After holding at a temperature of 85 ° C. and a humidity of 85% RH for a predetermined time, it was evaluated in the following three stages.
◯: Less than 1% decrease in light transmittance compared to 0 hour test (no turbidity)
Δ: Decrease in light transmittance by 1-5% compared to test 0 hour
X: The decrease in light transmittance is 5% or more compared to 0 hour test.

<Synthesis of unsaturated carbonyl-modified polymer>
(1) Single unit acryloyl-modified polybutadiene (hydrogenated type)
Urethane catalyst dibutyltin diversate 0.16 g, polymerization inhibitor ADK STAB AO-60 0.16 g, Nisseki Polybutene HV-15 1717 g, NISPOSB GI-3000 300 g of a number average molecular weight of 3000 and an iodine value of 21 or less were heated to 77 ° C. with stirring under bubbling. Charge 21.6 g of 2-acryloyloxyethyl isocyanate (manufactured by Showa Denko KK, product number Karenz AOI) (corresponding to 1.0 equivalent to the hydroxyl group contained in GI-3000) and react at 80 ° C. for 120 minutes. As a result, a single acryloyl-modified hydrogenated polybutadiene was obtained. The number average molecular weight of the obtained unit type acryloyl-modified hydrogenated polybutadiene was 4,800.
By the above synthesis, a mixing ratio (A: B) of polybutene (A) used as a solvent and synthesized acryloyl-modified hydrogenated polybutadiene (B) is obtained as a mixture of 80:15 (mass ratio). It was.

(2) Single unit acryloyl-modified polybutadiene (non-hydrogenated type)
In the synthesis example of the unit type acryloyl-modified polybutadiene (hydrogenated type), the same procedure was carried out except that NISPOSB G-3000 (non-hydrogenated polybutadiene diol having hydroxyl groups at both ends made by Nippon Soda) was used instead of NISSPOP GI-3000. . However, 2-acryloyloxyethyl isocyanate was added in an amount corresponding to 1.0 equivalent with respect to the hydroxyl group contained in G-3000. The number average molecular weight of the obtained unit type acryloyl-modified polybutadiene was 4,600.
The mixing ratio (A: B) of the polybutene (A) used as a solvent and the synthesized acryloyl-modified polybutadiene (non-hydrogenated) (B) by the above synthesis is 80:15 (mass ratio). Obtained as a mixture.

(3) Single unit acryloyl-modified polyisoprene (hydrogenated type)
In the synthesis example of the single unit acryloyl-modified polybutadiene (hydrogenated type), the same procedure was performed except that hydrogenated polyisoprene diol “Epol” having hydroxyl groups at both ends made by Idemitsu Kosan was used instead of NISSOPB GI-3000. However, 2-acryloyloxyethyl isocyanate was added in an amount corresponding to 1.0 equivalent with respect to the hydroxyl group contained in the epaul. The number average molecular weight of the obtained single acryloyl-modified hydrogenated polyisoprene was 3400.
By the above synthesis, a mixture ratio (A: B) of polybutene (A) used as a solvent and synthesized acryloyl-modified hydrogenated polyisoprene (B) is obtained as a mixture of 80:15 (mass ratio). It was.

(4) Methacryloyl-modified polyisoprene (non-hydrogenated type)
UC-102 manufactured by Kuraray was used.

<Ultraviolet curable resin composition No. Preparation of 1,3-6>
To the acryloyl-modified polybutadiene (hydrogenated type), acryloyl-modified polyisoprene (hydrogenated type), or acryloyl-modified polybutadiene (non-hydrogenated type) obtained in the above (1)-(3) in a mixture with polybutene, As a polymerizable compound, isobornyl acrylate (IB-A) (Tg = 94 ° C.) (manufactured by Nippon Shokubai) and / or 2-hydroxypropyl acrylate (Tg: −7 ° C.) (manufactured by Nippon Shokubai), as a photopolymerization initiator After mixing Irgacure TPO (monoacylphosphine oxide) (manufactured by BASF) in the ratio shown in Table 1, fumed silica (Aerosil # 300 manufactured by Evonik Japan) was added in the ratio shown in Table 1, and homomixer ( A resin composition was prepared by dispersing and stirring with a product of Primics.

<Ultraviolet curable resin composition No. Preparation of 2>
Kuraray UC-102, which is a methacryloyl-modified polyisoprene (non-hydrogenated type), and Nisseki polybutene HV-15 were mixed in the proportions shown in Table 1, and then isobornyl acrylate (IB-A) (Tg = 94 ° C.) (manufactured by Nippon Shokubai) and Irgacure TPO (monoacylphosphine oxide) (manufactured by BASF) at a ratio shown in Table 1, and then fumed silica (Aerosil # 300 manufactured by Evonik Japan) It added in the ratio shown in Table 1, and the resin composition was prepared by carrying out dispersion | distribution stirring with the homomixer (made by Primics).

<Ultraviolet curable resin composition No. Preparation of 7>
Except that the synthesis of acryloyl-modified polybutadiene (hydrogenated type) was carried out by changing the compounding ratio of each compound so that polybutene: acryloyl-modified hydrogenated polybutadiene = 20: 60 (mass ratio). Same as the preparation of 1. Isobornyl acrylate and a photopolymerization initiator were added to and mixed with the resulting polybutene: acryloyl-modified hydrogenated polybutadiene 20:60 (mass ratio) in the ratio shown in Table 1, and then fumed silica was added. It added in the ratio shown in Table 1, and the resin composition was prepared by carrying out dispersion | distribution stirring with the homomixer (made by Primics).

<Ultraviolet curable resin composition No. Evaluation of 1-7>
Composition no. For 1-7, the viscosity, curability, and dielectric constant were measured and evaluated based on the above measurement evaluation method.

Next, each composition was dropped onto a glass plate of a predetermined size in which silicone spacers of a predetermined thickness were arranged on four sides, filled in the frame, and then covered with a glass plate of the same size. In such a state, from a test piece having a laminated structure of glass plate / cured material layer of composition / glass plate, or from a glass plate, 385 nm light is irradiated at ³ J / cm ² with an LED type UV irradiation apparatus and cured. A sheet-like test piece from which the cured product of the composition was peeled was obtained. The turbidity of the obtained test piece was evaluated based on the evaluation measurement method.

  The evaluation result of turbidity was “△” or “◯”. For 1-4, the light transmittance, heat resistance, and moisture resistance were further evaluated. The above evaluation results are shown together in Table 1. In Table 1, “-” in the evaluation result column indicates that measurement was not performed.

As can be seen from Table 1, when hydroxypropyl acrylate is used as the polymerizable compound (No. 5), the (meth) acryloyl-modified (hydrogenated) conjugated diene polymer has a conjugated diene polymer portion that is non-hydrogenated. In the case of polybutadiene (No. 6), the compatibility with the polybutene used as the component A was poor, and a transparent cured product could not be obtained. The dielectric constant was 2.8 or more.
Further, as a (meth) acryloyl-modified (hydrogenated) conjugated diene polymer, even when the conjugated diene polymer portion is a hydrogenated polybutadiene, when the polybutene is not the main component (No. 7), it is still transparent. Not only was a cured product not obtained, but the dielectric constant was 2.8 or more.

  On the other hand, as the (meth) acryloyl-modified (hydrogenated) conjugated diene polymer, the conjugated diene polymer portion is hydrogenated polybutadiene, polyisoprene (non-hydrogenated type), or hydrogenated polyisoprene, and polybutene is the main component. In the case of (60% by mass or more in the composition) (No. 1-4), it was possible to obtain a transparent cured product. However, No. which does not contain fumed silica. No. 4 became cloudy under high temperature and high humidity conditions. On the other hand, No. containing fumed silica. The 1-3 composition has a dielectric constant of 2.5 or less, and a level that cannot be obtained with a cured product of a curable composition mainly composed of a (meth) acryloyl group-containing polymer that has been used conventionally. A low dielectric constant could be achieved. Moreover, it can be seen that even under high temperature and high humidity, white turbidity is suppressed, and it has been possible to achieve both low dielectric constant and white turbidity resistance under humidified conditions, which have been considered difficult in the past.

  Since the curable resin composition of the present invention provides a cured product having a low dielectric constant and excellent moisture resistance, a tablet in which the dielectric constant of a member to be used affects the operating sensitivity like a capacitive touch panel. It is suitable as an adhesive used between the transparent members of the mold terminal and a filler filling the gap, and can also be suitably used as a filler and an adhesive between other optical members.

Claims (9)

(A) 100 parts by mass of polybutene and / or polyisobutylene having a number average molecular weight of 300 to 1500;
(B) α, β-unsaturated carbonyl modification (hydrogenation) which is at least one selected from the group consisting of hydrogenated polybutadiene, hydrogenated polyisoprene, and polyisoprene having an α, β-unsaturated carbonyl group. 5 to 50 parts by mass of a conjugated diene polymer;
(C) 2 to 30 parts by mass of an alkyl or cycloalkyl ester having 6 to 20 carbon atoms of (meth) acrylic acid; and (D) 0.5 to 10 parts by mass of fumed silica having a primary average particle size of 50 nm or less. A curable resin composition. The curable resin composition according to claim 1, wherein the pour point of (A) polybutene and / or polyisobutylene is 0 ° C or lower. The (B) α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer is a (meth) acryloyl-modified hydrogenated polybutadiene having a urethane bond, a (meth) acryloyl-modified hydrogenated polyisoprene having a urethane bond, and The curable resin composition according to claim 1 or 2, which is at least one selected from the group consisting of (meth) acryloyl-modified polyisoprene having a urethane bond. The (B) α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer has an α, β-unsaturated carbonyl group in the side chain of hydrogenated polybutadiene, hydrogenated polyisoprene, or polyisoprene. The curable resin composition according to claim 1 or 2. The (B) α, β-unsaturated carbonyl-modified (hydrogenated) conjugated diene polymer is obtained by performing an α, β-unsaturated carbonyl modification reaction in the presence of the polybutene and / or polyisobutylene solvent of (A). The curable resin composition according to any one of claims 1 to 4, wherein Furthermore, (E) The curable resin composition of any one of Claims 1-5 formed by containing a photoinitiator. The curable resin composition according to any one of claims 1 to 6, wherein a cured product obtained by curing the curable resin composition has a relative dielectric constant of less than 2.8. Hardened | cured material obtained by hardening | curing the curable resin composition of any one of Claims 1-7 by energy ray irradiation. An image display device comprising the cured product according to claim 8.