JP2022083041A - Resin sheet, and laminate - Google Patents

Abstract

To provide a resin sheet which is excellent in coatability of a recession/projection part, has high flexibility and heat resistance, and can simply seal an electronic circuit board.SOLUTION: A resin sheet is formed of a resin composition containing a urethane-acrylic composite resin and a crosslinking agent, in which the urethane-acrylic composite resin is a resin obtained by connecting a urethane unit (A) and a (meth)acrylic unit (B) by a chain transfer agent residue, and the (meth)acrylic unit (B) has a constitutional unit derived from a crystalline (meth)acrylic monomer (b1) and a constitutional unit derived from a (meth)acrylic monomer (b2) having a crosslinkable group (excluding constitutional unit derived from (b1)).SELECTED DRAWING: None

Description

The present invention relates to a resin sheet and a laminate having excellent covering properties of uneven portions, high flexibility and heat resistance.

In recent years, many electronic control technologies have been adopted from the viewpoint of vehicle driving support and fuel efficiency, and along with this, the electronic control units have become larger and more installed. For this reason, an increase in vehicle weight and a shortage of installation space have become issues, and miniaturization of the electronic control unit is desired.

On the other hand, an electronic circuit board on which electronic components such as IC chips mounted on an electronic control unit are mounted is generally sealed with a sealing resin for the purpose of protecting the board from changes in the external environment such as water and dust. .. Various methods such as a potting method, a dipping method, a coating method, and a spraying method have been conventionally used as the sealing method, but these methods require thick coating and it is difficult to reduce the size sufficiently. There are challenges. Further, even if the sealing layer can be made into a thin film, there are problems that material loss occurs and the process time becomes long due to complicated work.

To solve such problems, for example, in Patent Documents 1 and 2, a resin sheet made of an epoxy resin, a curing agent, an inorganic filler, and a flame retardant is softened by its own weight by heat to cover the unevenness of electronic parts and cured as it is. A method for forming a sealing film has been proposed.

However, although these methods can simplify the encapsulation process of the electronic circuit board, if the inorganic filler is highly filled in order to suppress the fluidity, the crosslink formation becomes insufficient and the heat resistance is lost, and the filling amount of the inorganic filler is increased. If it is reduced, the fluidity of the epoxy resin is too high, so that the resin cannot sufficiently cover the convex portion, and it is difficult to achieve both fluidity and heat resistance. In addition, since the coating film after curing is hard and brittle, repeated heat cycles may cause peeling from the substrate, cracks, and extra stress applied to the substrate, electronic components, and solder joints, resulting in short circuits, disconnections, and cracks. There is a risk of current leakage and other malfunctions of the equipment.

Japanese Unexamined Patent Publication No. 2011-246596 Japanese Unexamined Patent Publication No. 2012-054363

An object of the present invention is to provide a resin sheet which has excellent covering property of uneven portions, has high flexibility and heat resistance, and can easily seal an electronic circuit board.

As a result of diligent studies, the present inventors have made urethane acrylics having a structural unit derived from a crystalline (meth) acrylic monomer and a structural unit derived from a (meth) acrylic monomer having a crosslinkable group. It has been found that a resin sheet formed from a composite resin and a resin composition containing a cross-linking agent can solve the above-mentioned problems.

The resin sheet according to one aspect of the present invention is a resin sheet formed of a urethane / acrylic composite resin and a resin composition containing a cross-linking agent, and the urethane / acrylic composite resin is a urethane unit (A) and ( The resin is formed by linking the meta) acrylic unit (B) with a chain transfer agent residue, and the (meth) acrylic unit (B) is a constituent unit derived from the crystalline (meth) acrylic monomer (b1). It is characterized by having a structural unit derived from a (meth) acrylic monomer (b2) having a crosslinkable group (excluding the structural unit derived from (b1)).

The resin sheet according to another aspect of the present invention is characterized in that the crystalline (meth) acrylic monomer (b1) is a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms. do.

In the resin sheet according to another aspect of the present invention, the urethane / acrylic composite resin contains the urethane unit (A) in the range of 30 to 70% by mass based on the mass of the urethane / acrylic composite resin. It is a feature.

The resin sheet according to another aspect of the present invention is characterized by being used for encapsulating an electronic device.

The laminate according to another aspect of the present invention is characterized by having the above resin sheet and a release material.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a resin sheet which has excellent covering property of uneven portions, has high flexibility and heat resistance, and can easily seal an electronic circuit board at a low temperature in a short time.

<Resin sheet>
The resin sheet of the present invention is formed of a urethane-acrylic composite resin in which a urethane unit (A) and a (meth) acrylic unit (B) are linked by a chain transfer agent residue, and a resin composition containing a cross-linking agent. The (meth) acrylic unit (B) is a structural unit derived from a crystalline (meth) acrylic monomer (b1) and a structural unit derived from a (meth) acrylic monomer (b2) having a crosslinkable group (provided that (however). It is characterized by having b1) (excluding the constituent units derived from it).
With such a configuration, the flexible urethane moiety and the self-aggregating acrylic moiety form a microphase-separated structure, and the crystalline (meth) acrylic monomer (b1) is formed even before curing. ) Retains a solid shape at room temperature due to the crystallization effect of), while it is derived from the urethane unit (A) at a relatively low temperature exceeding the crystallization temperature of the crystalline (meth) acrylic monomer (b1) by 20 to 40 ° C. While maintaining a constant cohesive force due to the cohesive force of, it softens due to the elimination of the crystallization effect and quickly follows the unevenness. After cross-linking, it exhibits excellent extensibility and adhesion due to the urethane site and excellent heat resistance due to the cross-linked structure of the acrylic site. As a result, the resin sheet of the present invention can exhibit excellent covering properties of uneven portions, and can exhibit high flexibility and heat resistance under the conditions of low temperature and short time of about 80 ° C. for 1 minute.
Therefore, the resin sheet of the present invention is suitably used for protecting various electronic circuit boards, that is, various substrates such as rigid substrates and FPC substrates.
In addition, the "chain transfer agent residue" in the present specification means a partial structure of a composite resin that can be identified as being derived from the chain transfer agent, and having "crystalline" has a melting point of 30. It is in the range of ~ 100 ° C. and means that it has a clear endothermic peak instead of a stepwise endothermic change in differential scanning calorimetry (DSC).

<Urethane / acrylic composite resin>
The urethane-acrylic composite resin in the present invention has a urethane unit (A), a structural unit derived from a crystalline (meth) acrylic monomer (b1), and a (meth) acrylic monomer (b2) having a crosslinkable group. ) Derived structural unit (excluding the structural unit derived from (b1)) and the (meth) acrylic unit (B) having are linked by a chain transfer agent residue, and the production method thereof is not limited. However, it can be preferably produced by the following method.
First, a urethane prepolymer having isocyanato groups at both ends, which is obtained by reacting a polyol and a polyisocyanate, is formed (hereinafter, step 1).
Next, a chain transfer agent is added to synthesize a urethane unit (A) having chain transfer agent residues at both ends of the urethane prepolymer (hereinafter, step 2).
Then, using the chain transfer agent residue contained in the obtained urethane unit (A), a structural unit derived from the crystalline (meth) acrylic monomer (b1) and a (meth) acrylic unit having a crosslinkable group are used. A polymer unit of an ethylenically unsaturated monomer is obtained by chain transfer polymerization of a structural unit derived from the body (b2) (excluding the structural unit derived from (b1)) and an ethylenically unsaturated monomer (excluding the structural unit derived from (b1)). B) is formed (hereinafter, step 3).
In this way, a urethane-acrylic composite resin in which the urethane unit (A) and the polymer unit (B) of the ethylenically unsaturated monomer are linked by a chain transfer agent residue can be obtained.
All of these reactions may be carried out with or without a solvent. When a solvent is used, the solvent may be removed under reduced pressure or normal pressure in the middle of the reaction or after the reaction is completed.

<Urethane unit (A)>
First, the urethane unit (A) of the urethane / acrylic composite resin will be described below.
The urethane-acrylic composite resin in the present invention can be formed by reacting a polyol and a polyisocyanate in a solvent-free or solvent-free manner. Since the urethane unit is flexible and has excellent adhesion to the base material, it can exhibit excellent coating properties.

[Polyol]
Examples of the polyol constituting the urethane unit (A) include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, vegetable oil-based polyols, other polyols including acrylic polyols, or composites thereof.
These polyols may be used alone or in combination of two or more.

(Polyether polyol)
The polyether polyol may be a compound having two or more hydroxyl groups and two or more ether bonds in the molecule, and examples thereof include polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, and the like. Examples thereof include polyethylene glycol, polypropylene glycol, poly (ethylene / propylene) glycol, and polytetramethylene glycol.
Examples of the polyether polyol include hexanediol, methylhexanediol, heptanediol, octanediol, and polyether polyols obtained by condensing a mixture thereof.

Further, as the polyether polyol, for example, a compound having at least two or more active hydrogen groups such as a low molecular weight polyol, an aliphatic amine compound, an aromatic amine compound, an alkanol amines, or a bisphenol is used as a starting material. Examples thereof include a polyol obtained by adding an alkylene oxide such as methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, or polyoxytetramethylene oxide.

Among the compounds having two or more active hydrogen groups, examples of the small molecule polyol include a bifunctional low molecule polyol and a trifunctional or higher functional small molecule polyol.

Examples of the bifunctional low molecular weight polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol. Neopentyl glycol, pentandiol, hexanediol, octanediol, nonanediol, dipropylene glycol, diethylene glycol, triethylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propane Diol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, polyoxyethylene glycol (additional moles: 10 or less), polyoxypropylene glycol (additional moles: 10 or less), cyclohexanediol , Cyclohexanedimethanol, Tricyclodecanedimethanol, Cyclopentadiene dimethanol, Dimerdiol, Bisphenol B, N, N-bis (2-hydroxypropyl) aniline, Dimethylolacetic acid, Dimethylolpropionic acid, Dimethylolbutanoic acid, 2, Examples thereof include 2-dimethylol butyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dihydroxypropionic acid and dihydroxybenzoic acid.

Examples of the trifunctional low molecular weight polyol include trimethylolethane, trimethylolpropane, 1,1,1-trimethylolbutane, 1,2,3-butanetriol, 1,2,4-butanetriol, 1, 2,6-Butantriol, trimethylolbutene, trimethylolpentene, trimethylolhexene, trimethylolhepten, trimethylolopten, trimethylolnonen, trimethylolpropane, trimethylolpropane, trimethylolpropane, trimethyloltrydecene , Trimethylolpentadecene, trimethylolhexadecene, trimethylolheptadecene, trimethyloloctadecene, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-Trimethylol-2-ethyl-hexane, 1,1,1-trimethylol-3-ethyl-hexane, trimethylolhexene, 1,2,3-octanetriol, 1,3,7-octane Triol, 3,7-dimethyl-1,2,3-octanetriol, 1,1,1-, 1,1,1-trimethylolpropane, 1,2,10-decantryol, 1,1,1-triol Methylolisoheptadecane, 1,1,1-trimethylol-seA-butane, 1,1,1-trimethylol-tert-pentane, 1,1,1-trimethylol-tert-nonan, 1,1,1- Trimethylol-tert-tridecane, 1,1,1-trimethylol-tert-heptadecane, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, 1,1,1-trimethylol-3-ethyl-hexane, 1,1,1-trimethylolisoheptadecane, 1,2,3,4- Butanetetraol, pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, diglycerin, triglycerin, polyglycerin, trimethylolethane, dimethylolpropane, tris (2-hydroxyethyl) isocyanurate, benzene-1,3. Includes 5-triol, benzene-1,2,3-triol, stilben-3,4', 5-triol, shoeclaws, inositol, sorbitan, sorbitol, mannitol, saccharose, cellulose, and xylitol. To.

Among the compounds having two or more active hydrogen groups, examples of the aliphatic amine compounds include ethylenediamine, isophoronediamine, triethylenetetramine, diethylenetriamine, and triaminopropane. Examples of aromatic amine compounds include toluenediamine and diphenylmethane-4,4-diamine. Examples of alkanolamines include ethanolamine and diethanolamine. Examples of bisphenols include bisphenol B, bisphenol BP, bisphenol C, bisphenol A, bisphenol E, and bisphenol F.

(Polyester polyol)
Examples of the polyester polyol include a polyester polyol in which the above-mentioned low molecular weight polyol and a dibasic acid component are condensed and reacted.

Examples of the dibasic acid component include terephthalic acid, adipic acid, azelaic acid, sebatic acid, dimer acid, hydrogenated dimer acid, anhydrous phthalic acid, isophthalic acid, trimellitic acid, glutaric acid, pimelic acid, suberic acid, and sebacin. Examples thereof include aliphatic or aromatic dibasic acids such as acids, and anhydrides thereof.

Examples of the polyester polyol include polyester polyols obtained by ring-opening polymerization of cyclic ester compounds such as lactones such as ε-caprolactone, poly (β-methyl-γ-valerolactone) and polyvalerolactone.

(Polycarbonate polyol)
Examples of the polycarbonate polyol include reaction products of the above-mentioned small molecule polyols and carbonate compounds such as dialkyl carbonates, alkylene carbonates and diaryl carbonates.
Examples of the dialkyl carbonate include dimethyl carbonate and diethyl carbonate. Examples of the alkylene carbonate include ethylene carbonate and the like. Examples of the diaryl carbonate include diphenyl carbonate and the like.

(Polyolefin-based polyol)
Examples of the polyolefin-based polyol include hydroxyl group-containing polybutadiene, hydrogenated hydroxyl group-containing polybutadiene, hydroxyl group-containing polyisoprene, hydrogenated hydroxyl group-containing polyisoprene, hydroxyl group-containing chlorinated polypropylene, and hydroxyl group-containing chlorinated polyethylene.

(Vegetable oil-based polyol)
Examples of the vegetable oil-based polyol include castor oil derived from plants, dimer acid, or a polyol made from soybean oil.

The number average molecular weight of these polyols is preferably 500 or more and less than 5,000, and more preferably 700 or more and less than 3,500.

Further, the above-mentioned low molecular weight polyols, aliphatic amine compounds, and aromatic amine compounds can be used in combination for the purpose of adjusting the urethane bond concentration and introducing various functional groups.

[Polyisocyanate]
Examples of the polyisocyanate constituting the urethane unit (A) include aromatic, aliphatic, and alicyclic polyisocyanates. These may be used individually by 1 type, or may be used in combination of 2 or more type.

Examples of the aromatic polyisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylenedi isocyanate, p-phenylenedi isocyanate, 4,4'-diphenylmethane diisocyanate, and 2,4-diphenylmethane diisocyanate. 2,2'-Diphenylmethane diisocyanate, 1,5-naphthalenediocyanate, trizine diisocyanate, xylylene diisocyanate, m-tetramethylxylene diisocyanate, p-tetramethylxylene diisocyanate, 3,3'-dimethyl- Examples thereof include 4,4'-biphenylenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediocyanate, 3,3'-dichloro-4,4'-biphenylenediocyanate, and 1,5-tetrahydronaphthalenedi isocyanate.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylenedisisocyanis, 1,3-butyrenisisisis, and dodecamethylene diisocyanate. 2,4,4-trimethylhexamethylene diisocyanis, lysine diisocyanis, lysine ester triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate tetramethylene diisocyanate, pentamethylene diisocyanate, trimethylhexa Methylene diisocyanate can be mentioned.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, methyl-2,4-cyclohexanediisocyanate, and methyl-2,6-. Cyclohexanediisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanitemethyl) cyclohexane, hydrogenated xylylene diisocyanate, dimerate diisocyanate, norbornene diisocyanate can be mentioned.

The reaction between the polyol and the polyisocyanate can be carried out preferably in a solvent-free manner using a known urethanization reaction, and by adding an excess of the polyisocyanate, a urethane prepolymer having isocyanato groups at both ends can be obtained. be able to. The molar ratio (number of moles of NCO / number of moles of OH) between the isocyanato group and the hydroxyl group during the reaction is preferably 1.05 to 2.00, more preferably 1.10 to 1.50.
In the urethanization reaction, a catalyst may be used for the purpose of adjusting the reactivity.

As the catalyst, known metal-based catalysts, amine-based catalysts and the like can be used. Examples of the metal-based catalyst include dibutyltin dilaurate, tin octoate, dibutyltin di (2-ethylhexoate), 2-ethylhexoate lead, 2-ethylhexyl titanate, titanium ethylacetate, and 2-ethylhe. Examples thereof include xoate iron, 2-ethylhexoate cobalt, zinc naphthenate, cobalt naphthenate, and tetra-n-butyl tin. Examples of the amine-based catalyst include tertiary amines such as tetramethylbutanediamine. The blending amount of the catalyst is preferably in the range of 0.05 to 1 mol% based on the mass of the polyol.

<Chain transfer agent>
The chain transfer agent in the present invention is not particularly limited, but is preferably a chain transfer agent having a sulfanil group. As the chain transfer agent having a sulfanil group, those having a functional group capable of reacting with an isocyanato group and a sulfanil group in the molecule are preferably used. When the chain transfer agent is used, the terminal isocyanato group in the urethane prepolymer reacts with the functional group capable of reacting with the isocyanato group in the chain transfer agent to form a urethane unit (A) having a sulfanyl group at both ends. Can be done. The chain transfer agent can be used alone or in combination of two or more from known chain transfer agents.

Examples of the functional group capable of reacting with the isocyanato group include a hydroxyl group or an amino group, and an amino group is preferable from the viewpoint of reactivity. Since the amino group is more reactive than the sulfanyl group, it preferentially reacts with the terminal isocyanato group of the urethane prepolymer to form a urea bond, and the sulfanyl group is efficiently introduced into the terminal of the urethane unit (A). Can be done. A compound having one amino group and one sulfanil group in the molecule is more preferable as such a chain transfer agent.

Examples of the compound having one amino group and one sulfanyl group in the molecule include 2-aminoethanethiol, 3-aminopropyl-1-thiol, 1-aminopropyl-2-thiol and 4-amino-1. -Amino alkanethiols such as butanethiol; examples thereof include aminobenzenethiols such as 2-aminothiophenol, 3-aminothiophenol and 4-aminothiophenol. Among these, aminoalkanethiols are preferable, and 2-aminoethanethiol is more preferable.

[Content of urethane unit (A)]
The urethane / acrylic composite resin in the present invention contains the urethane unit (A) in a range of preferably 30 to 70% by mass, more preferably 35 to 65% by mass, based on the mass of the urethane / acrylic composite resin. It is included in the range of%. When the content of the urethane unit (A) is 30 to 70% by mass, it is preferable because it is excellent in uneven coating property, flexibility and heat resistance of the cured film.

The weight average molecular weight of the urethane unit (A) is not particularly limited, and is preferably in the range of 3,000 to 200,000. When it is 3,000 or more, the adhesive strength is excellent, and when it is 200,000 or less, the viscosity can be easily adjusted.

<(Meta) Acrylic unit (B)>
The (meth) acrylic unit (B) in the present invention is a structural unit derived from a crystalline (meth) acrylic monomer (b1) and a structural unit derived from a (meth) acrylic monomer (b2) having a crosslinkable group. (However, the structural unit derived from (b1) is excluded), and more specifically, a crystalline (meth) acrylic monomer (b1) and a (meth) acrylic monomer having a crosslinkable group (meth). It is a polymer of an ethylenically unsaturated monomer containing b2) (excluding (b1)). Specifically, the urethane unit (A) having chain transfer agent residues at both ends obtained in step 2, and the crystalline (meth) acrylic monomer (b1) and having a crosslinkable group (meth). By polymerizing an ethylenically unsaturated monomer containing the acrylic monomer (b2) (excluding (b1)) in the presence of a polymerization initiator, the urethane unit (A) and (meth) acrylic are polymerized. A urethane-acrylic composite resin which is a block polymer in which the unit (B) is linked by a chain transfer agent residue can be obtained.

The structural unit derived from the crystalline (meth) acrylic monomer (b1) causes the (meth) acrylic unit (B) to crystallize at room temperature, thereby increasing the cohesive force of the urethane-acrylic composite resin, even when uncured. The sheet shape can be maintained. On the other hand, when the crystallization temperature is exceeded, the cohesive force is immediately eliminated, the resin sheet softens, and a film is formed following the unevenness of the electronic circuit board. Further, by cross-linking the (meth) acrylic unit (B) with a cross-linking agent, the obtained cured film becomes a tough film having waterproof, antifouling and heat resistant properties, and seals the electronic circuit board. Can be done.

[Crystalline (meth) acrylic monomer (b1)]
The crystalline (meth) acrylic monomer is not particularly limited as long as it is the (meth) acrylic monomer having the above-mentioned "crystallinity", and has, for example, a linear alkyl group having 16 or more carbon atoms (). Meta) Acrylic can be used. Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms include cetyl (meth) acrylate, stearyl (meth) acrylate, eicocil (meth) acrylate, and behenyl (meth) acrylate. .. From the viewpoint of crystallinity, it preferably has a linear alkyl group having 18 or more carbon atoms.

[Content rate of crystalline (meth) acrylic monomer (b1)]
The content of the crystalline (meth) acrylic monomer (b1) is preferably in the range of 50 to 95% by mass based on the total mass of the monomers constituting the (meth) acrylic unit (B). More preferably, it is in the range of 55 to 90% by mass. When the content of the crystalline (meth) acrylic monomer (b1) is 50% by mass or more, the uneven coating property is excellent, and when it is 95% by mass or less, the flexibility and heat resistance of the cured film are excellent.

[(Meta) acrylic monomer (b2) having a crosslinkable group (excluding (b1))]
The (meth) acrylic monomer (b2) having a crosslinkable group is not particularly limited as long as it has a crosslinkable group in the molecule that can react with the crosslinking agent described later. Examples of such a crosslinkable group include a hydroxyl group, an epoxy group, a carboxy group, an isocyanato group and a block thereof.

Examples of the (meth) acrylic monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , 2-Hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3-allyloxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropylphthalate or caprolactone adducts of these monomers ( Examples of the number of added moles are 1 to 5), polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, and glycerin mono (meth) acrylate.

Examples of the (meth) acrylic monomer having an epoxy group include (meth) glycidyl acrylate, (meth) acrylic acid-3,4-epoxybutyl, (meth) acrylic acid-4,5-epoxypentyl, and (. Examples include (meth) acrylic acid-6,7-epoxypentyl, (meth) acrylic acid-3,4-epoxycyclohexyl, 4-hydroxybutyl acrylate glycidyl ether, and lactone-modified (meth) acrylic acid-3,4-epoxycyclohexyl. ..

Examples of the (meth) acrylic monomer having a carboxy group include (meth) acrylic acid, acrylic acid dimer, itaconic acid, maleic acid, fumaric acid, crotonic acid, α- (hydroxymethyl) (meth) acrylic acid, and the like. 2- (Meta) acryloyloxyethyl phthalate, 2- (meth) acryloyloxypropylphthalate, 2- (meth) acryloyloxyethyl hexahydrophthalate, 2- (meth) acryloyloxypropylhexahydrophthalate, β-carboxyethyl (meth) ) Acrylate, ethylene oxide-modified succinic acid (meth) acrylate, ω-carboxypolycaprolactone (meth) acrylate, p-vinylbenzoic acid.

Examples of the (meth) acrylate monomer having an isocyanato group and a block thereof include (meth) acryloyl isocyanate, 2-isocyanatoethyl (meth) acrylate, 2- (meth) acryloyloxyethoxyethyl isocyanate, 1,1. -(Bis (meth) acryloyloxymethyl) ethyl isocyanate, m- (meth) acryloylphenyl isocyanate, α, α-dimethyl-4-isopropenylbenzyl isocyanate can be mentioned.

[Content rate of (meth) acrylic monomer (b2) having a crosslinkable group]
The content of the (meth) acrylic monomer (b2) having a crosslinkable group is preferably in the range of 5 to 35% by mass based on the total mass of the monomers constituting the (meth) acrylic unit (B). Is. When the content of the (meth) acrylic monomer (b2) having a crosslinkable group is 5 to 35% by mass, the uneven coating property, the flexibility of the cured film and the heat resistance are excellent.

[Other monomers]
The monomer other than the monomers (b1) and (b2) used for forming the (meth) acrylic unit (B) may be copolymerizable with the monomers (b1) and (b2). The present invention is not particularly limited, and can be appropriately selected from known ethylenically unsaturated monomers.
Examples of such other ethylenically unsaturated monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (. Meta) acrylate, tertiary butyl (meth) acrylate, isoamyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, Linear or branched alkyl (meth) acrylates such as lauryl (meth) acrylate, tridecyl (meth) acrylate, isomiristyl (meth) acrylate; cyclohexyl (meth) acrylate, tertiarybutylcyclohexyl (meth) acrylate, dicyclopentanyl. Cyclic alkyl (meth) acrylates such as (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate; tri Fluoroalkyl (meth) acrylates such as fluoroethyl (meth) acrylate, octafluoropentyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, 3 -Methyl-3-oxetanyl (meth) acrylate and other (meth) acrylates having a heterocycle; benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, nonylphenoxypolyethylene glycol (meth) (Meta) acrylates having an aromatic ring such as acrylate; methoxypolyethylene glycol mono (meth) acrylate, octoxypolyethylene glycol polypropylene glycol mono (meth) acrylate, lauroxypolyethylene glycol mono (meth) acrylate, phenoxypolyethylene glycol mono ( Meta) Acrylate, Phenoxy Polyethylene Glycol Polypropylene Glycol Mono (Meta) Acrylate, Polyethylene Glycol Monomethyl Ether (Meta) Acrylate, Lauroxy Polyethylene Glycol Mono (Meta) Acrylate, Noni Ruphenoxypolyethylene glycol mono (meth) acrylate, nonylphenoxypolypolyglycol mono (meth) acrylate, nonylphenoxypolyethylene glycol polypropylene glycol mono (meth) acrylate, phenoxypolyethylene glycol mono (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, n -(Meta) acrylates having an alkyl ether group such as butoxyethyl (meth) acrylate, n-butoxydiethylene glycol (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate; styrene, α -Vinyls such as methylstyrene and vinyl acetate; (meth) acrylamide, N-methyl (meth) acrylamide, N-butyl (meth) acrylamide, diacetone (meth) acrylamide, N-methoxymethyl- (meth) acrylamide, N- Ethoxymethyl- (meth) acrylamide, N-propoxymethyl- (meth) acrylamide, N-butoxymethyl- (meth) acrylamide, N-pentoxymethyl- (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N , N-dibenzyl (meth) acrylamide, methacrylicformamide, N-methyl N-vinylacetamide, N-vinylpyrrolidone, N, N-di (methoxymethyl) acrylamide, N-ethoxymethyl-N-methoxymethyl (meth) acrylamide, N, N-di (ethoxymethyl) (meth) acrylamide, N-ethoxymethyl-N-propoxymethyl (meth) acrylamide, N, N-di (propoxymethyl) (meth) acrylamide, N-butoxymethyl-N- ( Propoxymethyl) (meth) acrylamide, N, N-di (butoxymethyl) (meth) acrylamide, N-butoxymethyl-N- (methoxymethyl) (meth) acrylamide, N, N-di (pentoxymethyl) (meth) ) (Meta) acrylates having a nitrogen atom such as acrylamide, N-methoxymethyl-N- (pentoxymethyl) (meth) acrylamide, and cinnamic acid amide;
These may be used individually by 1 type, or may be used in combination of 2 or more type.

[Polymer initiator]
As the polymerization initiator, known azo compounds and organic peroxides can be used.
Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis (cyclohexane1-carbonitrile), 2. , 2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), 2,2'-azobis (4-methoxy-2,4- Dimethylvaleronitrile), dimethyl 1,1'-azobis (1-cyclohexanecarboxylate), dimethyl 2,2'-azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid) ), 2,2'-Azobis (2-hydroxymethylpropionitrile), or 2,2'-azobis [2- (2-imidazolin-2-yl) propane].
Examples of the organic peroxide include benzoyl peroxide, t-butylperoxy2-ethylhexaate, t-butylperbenzoate, cumenehydroperoxide, diisopropylperoxydicarbonate, and di-n-propylperoxydi. Carbonate, di (2-ethoxyethyl) peroxydicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, Diacetyl peroxide can be mentioned.
These may be used individually by 1 type, or may be used in combination of 2 or more type.

The amount of the polymerization initiator used is preferably 0.001 to 15% by mass based on the total mass of the ethylenically unsaturated monomers forming the (meth) acrylic unit (B). A range of 0.001 to 15% by mass is preferable because chain transfer polymerization effectively proceeds.

[Weight average molecular weight of (meth) acrylic unit (B)]
The weight average molecular weight of the (meth) acrylic unit (B) is not particularly limited, and is preferably 2,000 to 200,000. When it is 2,000 or more, the unevenness covering property is excellent, and when it is 200,000 or less, the viscosity can be easily adjusted.

[Weight average molecular weight of urethane / acrylic composite resin]
The weight average molecular weight of the urethane-acrylic composite resin is not particularly limited, and is preferably in the range of 5,000 to 300,000, more preferably in the range of 10,000 to 100,000. When it is 5,000 or more, the unevenness covering property is excellent, and when it is 300,000 or less, the viscosity can be easily adjusted.

<Solvent>
The reaction in producing the urethane / acrylic composite resin may be carried out using a solvent. One of these solvents may be used alone, or two or more of them may be used in combination.
The solvent that may be used for the reaction between the polyol and the polyisocyanate is not particularly limited as long as it does not react with the isocyanato group. For example, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, toluene and xylene. , Anisol, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N-vinylpyrrolidone, N-methylcaprolactum, dimethyl Examples thereof include sulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, m-cresol, γ-butyrolactone and γ-valerolactone.
As the solvent that may be used for the reaction between the urethane prepolymer and the chain transfer agent, alcohols such as ethanol, isopropanol, tertiary butanol, and diacetone alcohol can be used in addition to the above-mentioned solvents.

<Crosslinking agent>
The resin sheet of the present invention is formed from a resin composition containing the above-mentioned urethane / acrylic composite resin and a cross-linking agent. When the crosslinkable group derived from the (meth) acrylic monomer (b2) reacts with the crosslinking agent and is cured, a cured product having excellent flexibility and heat resistance can be obtained.
The cross-linking agent is not particularly limited as long as it has a functional group capable of reacting with the cross-linking group in the molecule, and examples of such a functional group include an epoxy group, an acid anhydride group and a phenol group. Examples thereof include an isocyanenato group and a block thereof, an amino group, a hydroxyl group, or a carboxy group. As the cross-linking agent, one type may be used alone, or two or more types may be used in combination.

Examples of the cross-linking agent having an epoxy group include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, and trimethylolpropane triglycidyl ether. Diglycidyl aniline, N, N, N', N'-tetraglycidyl-m-xylylene diamine, 1,3-bis (N, N'-diglycidyl aminomethyl) cyclohexane, N, N, N', N' -Tetraglycidyl aminophenylmethane, triglycidyl isocyanurate, triglycidyl-p-aminophenol can be mentioned.

Examples of the cross-linking agent having an acid anhydride group include phthalic anhydride, trimellitic anhydride, and maleic anhydride.

The cross-linking agent having a phenol group may be a monomer compound or a polymer compound. The cross-linking agent having a phenol group, which is a polymer compound, may be a polymer (homopolymer) of a single monomer, or may be a copolymer (copolymer) of a plurality of types of monomers. Further, the cross-linking agent having a phenol group may be any of a random copolymer, a block copolymer or a graft copolymer.
Examples of the cross-linking agent having a phenol group include bisphenol A, bisphenol F, bisphenol S, resorcin, catechol, hydroquinone, fluorene bisphenol, 4,4'-biphenol, 4,4', 4 "-trihydroxytriphenylmethane, and the like. Naphthalenediol, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, calixarene, novolak type phenolic resin (for example, phenol novolac resin, cresol novolak resin, bisphenol A novolak resin, bisphenol S novolak resin, resorcin novolac) Polyhydric phenol novolak resin synthesized from polyhydric hydroxy compound represented by resin and formaldehyde, naphthol-phenol co-condensed novolak resin, naphthol-cresol co-condensed novolak resin, naphthol novolak resin, and alkoxy group-containing aromatic ring-modified novolak. Resin (a polyhydric phenol compound in which a phenol nucleus and an alkoxy group-containing aromatic ring are linked with formaldehyde)), an aralkyl-type phenol resin (for example, a phenol aralkyl resin such as Zyroc resin and a naphthol aralkyl resin), an aromatic hydrocarbon formaldehyde resin modification. Phenol resin, dicyclopentadienephenol-added resin, trimethylolmethane resin, tetraphenylol ethane resin, biphenyl-modified phenol resin (polyhydric phenol compound in which phenol nuclei are linked by bismethylene group), biphenyl-modified naphthol resin (bismethylene group) Examples thereof include polyhydric phenol compounds such as polyhydric naphthol compounds to which phenol nuclei are linked) and aminotriazine-modified phenolic resins (polyhydric phenol compounds to which phenol nuclei are linked by melamine, benzoguanamine, etc.).

As the cross-linking agent having an isocyanato group, for example, the description in the above-mentioned [Polyisocyanate] section can be incorporated. Further, as the cross-linking agent having an isocyanato group, the biuret body, the nurate body, the adduct body, or other condensate of the polyisocyanate may be used.
Examples of the biuret form include a biuret form of hexamethylene diisocyanate.
Examples of the nurate form include a nurate form of hexamethylene diisocyanate, a nurate form of isophorone diisocyanate, and a nurate form of tolylene diisocyanate.
Examples of the adduct body include a hexamethylene diisocyanate adduct body of trimethylolpropane, an isophorone diisocyanate adduct body of trimethylolpropane, and an adduct body of toluene diisocyanate.
Examples of other condensates include polyfunctional compounds of compounds having an isocyanato group, carbodiimide modified products, biuret modified products, and allophanate modified products, and examples thereof include polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate biuret products, and carbodiimide modified products. Examples include diphenylmethane diisocyanate.

Examples of the cross-linking agent having an isocyanato group-blocking agent include those obtained by blocking the above-mentioned cross-linking agent having an isocyanato group with a known blocking agent. Examples of the blocking agent include phenols, alkylphenols, active methylene compounds, oximes, lactams, sodium bisulfites, and imidazoles.

Examples of the cross-linking agent having an amino group include the above-mentioned aliphatic amine compounds and aromatic amine compounds, as well as JEFFAMINE D-230, D-400, D-2000, T-403, and T-3000 under the product names. Examples thereof include bifunctional or higher-functional polyether amines such as (all manufactured by HUNTSMAN).

As the cross-linking agent having a hydroxyl group, for example, the description of "small molecule polyol" in the above-mentioned (polyether polyol) section can be incorporated.

Examples of the cross-linking agent having a carboxy group include succinic acid, adipic acid, sebacic acid, maleic acid, phthalic acid, naphthalenedicarboxylic acid, methylphthalic acid, cyclohexanedicarboxylic acid, methylcyclohexanedicarboxylic acid, methylnorbornenedicarboxylic acid and tetrahydrophthalic acid. , Trimellitic acid, trimesic acid, pyromellitic acid, naphthalenetetracarboxylic acid and the like.

The molar ratio of the functional group in the cross-linking agent to the cross-linking group in the urethane / acrylic composite resin (the number of moles of the functional group in the cross-linking agent / the number of moles of the cross-linking group in the urethane-acrylic composite resin) is preferable. Is 0.2 to 10.0, more preferably 0.5 to 5.0. A molar ratio of 0.2 to 10.0 is preferable because it has excellent flexibility.

<Resin sheet>
The resin sheet of the present invention can be obtained by molding the above-mentioned resin composition into a sheet. The method for producing the resin sheet is not particularly limited. For example, a urethane / acrylic composite resin, a cross-linking agent, and a solvent are uniformly stirred and mixed to obtain a resin composition, and then coated on a release film using a doctor blade or the like. It can be manufactured by working, drying in an oven, and then cooling to room temperature to solidify. The temperature of the oven is usually in the range of 60 ° C to 100 ° C, and the thickness of the resin sheet is preferably 100 μm to 3 mm.

[Filler]
The resin sheet of the present invention may contain a filler as long as the effect of the present invention is not impaired. Examples of the filler include colorants such as titanium oxide and carbon black; metal powders such as ferrite; inorganic fibers such as glass fibers and metal fibers; organic fibers such as carbon fibers and aramid fibers; aluminum nitride, boron nitride and hydroxide. Heat transfer agents such as aluminum, alumina, magnesium oxide, carbon nanotubes, expanded graphite; inorganic whisker such as glass beads, glass balloons, glass flakes, glass fibers, calcium carbonate, magnesium carbonate, potassium titanate whisker, zinc oxide whisker; Fillers such as talc, silica, calcium silicate, kaolin, caustic soil, montmorillonite, graphite, pebbles, evo powder, cotton floc, cork powder, barium sulfate, fluororesin and the like; The filler may be used alone or in combination of two or more.

The resin sheet of the present invention further comprises a curing accelerator, an antioxidant, an antioxidant, an antioxidant, a weather resistant agent, an ultraviolet absorber, an antiblocking agent, and a crystal nucleating agent, as long as the effects of the present invention are not impaired. It may contain known additives such as flame retardant, vulcanizing agent, vulcanization aid, antibacterial / antifungal agent, dispersant, anticoloring agent, foaming agent, rust preventive agent and the like.

By using the resin sheet of the present invention, for example, the electronic device can be sealed as follows. First, the resin sheet is laminated on the electronic circuit board and heated in an atmosphere of 60 ° C. to 100 ° C. for 30 to 60 seconds. Here, it immediately softens and easily follows the unevenness of the electronic component by its own weight to form a coating film. Then, it is heated for 10 to 60 minutes in an atmosphere of 80 ° C. to 120 ° C., cured and sealed. However, the method for sealing the electronic circuit board with the resin sheet of the present invention is not limited to the above.

Since the resin sheet of the present invention can greatly simplify the sealing process and can be sealed at a low temperature, it can be applied to an electronic circuit board having a low heat resistant temperature. In addition, it has excellent flexibility and heat resistance, and is suitably used for protecting various electronic circuit boards, that is, various boards such as rigid boards and FPC boards.

Hereinafter, the present invention will be described in more detail by way of examples, but the following examples do not limit the scope of rights of the present invention in any way. Unless otherwise specified, "parts" and "%" in the examples represent "parts by mass" and "% by mass", respectively.

<Weight average molecular weight (Mw)>
The weight average molecular weight (Mw) of the resin was determined by GPC (gel permeation chromatography) as a conversion value using standard polystyrene. For the measurement, GPC-8020 (manufactured by Tosoh) as a GPC device, tetrahydrofuran as an eluent, and TSKgelSuperHM-M (manufactured by Tosoh) as a column were connected in series, and the flow rate was 0.6 ml / min, the injection amount was 10 μl, and the column was used. The procedure was carried out under the condition of a temperature of 40 ° C.

<Solid content concentration>
The solid content concentration of the resin was based on JISK5601-1-2, and the heating residue when measured at a heating temperature of 150 ° C. and a heating time of 20 minutes was used.

The abbreviations of the compounds in the present specification are shown below.
<Polyol>
T-5651: bifunctional polycarbonate polyol, number average molecular weight 1,000, hydroxyl value 113 mgKOH / g, trade name "Duranol T5651", manufactured by Asahi Kasei Co., Ltd. PTG-1000SN; bifunctional polytetramethylene ether glycol, number average molecular weight 1 000, hydroxyl value 112 mgKOH / g, Hodogaya Chemical Co., Ltd. 112 mgKOH / g, Adeca Co., Ltd. <polyisocyanate>
・ IPDI: Isophorone diisocyanate

<(Meta) acrylic monomer>
SA: stearyl acrylate, SMA: stearyl methacrylate, VA: behenyl acrylate, AA: acrylic acid, HEMA: 2-hydroxyethyl methacrylate, BMA: butyl methacrylate

<Crosslinking agent>
-JER630: p-aminophenol type liquid epoxy resin, product name "jER630", manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 94.3 g / eq
BL3370: Aliphatic blocked isocyanate, product name "Death Module BL3370", manufactured by Sumika Bayer Urethane Co., Ltd., solid content concentration 70%, NCO content 8.9%

<Catalyst>
-C11Z-CN: 1-cyanoethyl-2-undecylimidazole, product name "Curesol C11Z-CN", manufactured by Shikoku Chemicals Corporation-DBTDL: dibutyl tin dilaurylate

<Manufacturing of urethane / acrylic composite resin>
(Manufacturing Example 1)
In a reaction vessel equipped with a nitrogen gas introduction tube, a stirrer, a thermometer, and a recirculator, 74.9 parts of T-5651 as a polyol, 25.1 parts of isophorone diisocyanate as a polyisocyanate, and dibutyltin dilaurate as a catalyst 0. 01 parts were charged and stirred uniformly, and then reacted at 90 ° C. for 5 hours under a nitrogen atmosphere to obtain a urethane prepolymer.
Then, the mixture was cooled to 80 ° C., 11.0 parts of methyl ethyl ketone as a solvent, 31.7 parts of toluene, and 5.5 parts of 2-aminoethanethiol as a chain transfer agent were added, and the mixture was reacted at 75 ° C. for 2 hours to make urethane. Got a unit. The end point of the reaction was confirmed by FT-IR by disappearance of the peak derived from the isocyanato group (around 2270 cm ^-1 ).
Next, as the crystalline (meth) acrylic monomer (b1), 135.4 parts of SA, as the (meth) acrylic monomer (b2) having a crosslinkable group, 12.3 parts of AA, and other ethylenic properties. Toluene was added to 98.5 parts of BMA as an unsaturated monomer so that the ratio of the solvent in the reaction vessel was 40%, and the mixture was uniformly stirred and then heated to 75 ° C. under a nitrogen atmosphere. To this, 0.08 part of 2,2'-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added in 13 portions every 30 minutes, and the reaction was further carried out for another 2 hours after the addition of the polymerization initiator (). Meta) Acrylic unit was formed.
Toluene was added to adjust the solid content concentration to 60%, and the urethane-acrylic composite resin solution of Production Example 1 was obtained.

(Production Examples 2 to 15, Comparative Production Examples 1 to 2)
The same operations as in Production Example 1 were carried out except that the compounds and compounding compositions shown in Table 1 were changed, to obtain urethane / acrylic composite resin solutions of Production Examples 2 to 15 and Comparative Production Examples 1 to 2, respectively.

Weight average molecular weight of the obtained urethane / acrylic composite resin, content of urethane unit (A) in urethane / acrylic composite resin (%), crystalline (meth) acrylic single amount in (meth) acrylic unit (B) Table 1 shows the content (%) of the body (b1) and the content of the (meth) acrylic monomer (b2) having a crosslinkable group in the (meth) acrylic unit (B).

(Comparative Production Example 3) Urethane resin In a reaction vessel equipped with a nitrogen gas introduction pipe, a stirrer, a thermometer, and a recirculator, 100.0 parts of T-5651 as a polyol, 14.9 parts of isophorone diisocyanate as a polyisocyanate, and a catalyst. As a result, 0.01 part of dibutyltin dilasate was charged, stirred uniformly, reacted at 90 ° C. for 5 hours under a nitrogen atmosphere, and further added 76.6 parts of toluene to obtain a urethane resin solution for comparison. The weight average molecular weight of the obtained urethane resin was 8,300, and the solid content concentration was 60%.

(Comparative Production Example 4) Acrylic resin In a reaction vessel equipped with a nitrogen gas introduction tube, a stirrer, a thermometer, and a recirculator, 137.3 parts of SA, 19.6 parts of AA, and 39.2 parts of n-butyl methacrylate. After adding 7.3 parts of 2-ethylhexyl thioglycolate and 136.0 parts of toluene and stirring uniformly, the temperature was raised to 75 ° C. under a nitrogen atmosphere. To this, 0.1 part of 2,2'-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added in 13 portions every 30 minutes, and after all the polymerization initiators were added, the reaction was further carried out for 2 hours. Acrylic resin solution for comparison was obtained. The weight average molecular weight of the obtained acrylic resin was 8,900, and the solid content concentration was 60%.

(Comparative Manufacturing Example 5)
DER383J (bisphenol A type epoxy resin, epoxy equivalent 190 g / eq, manufactured by Dow Chemical Co., Ltd.) 20 parts, NC3300 (biphenyl skeleton-containing polyfunctional epoxy resin, epoxy equivalent 285 g / eq, manufactured by Nippon Kayaku Co., Ltd.) 80 parts, dicyandiamide 4 parts, U-CAT3502T (aromatic dimethylurea, manufactured by San-Apro) 4 parts, FB-959 (spherical silica, particle size 25 μm, manufactured by Denki Kagaku Kogyo) 300 parts, H42M (aluminum hydroxide (particle size 1.5 μm) , Showa Denko Co., Ltd.) 20 parts were charged in a kneader and stirred and mixed at 75 ° C. for 1 hour to obtain a resin composition for comparison.

(Comparative Manufacturing Example 6)
DER383J (bisphenol A type epoxy resin, epoxy equivalent 190 g / eq, manufactured by Dow Chemical Co., Ltd.) 15 parts, NC3300 (biphenyl skeleton-containing polyfunctional epoxy resin, epoxy equivalent 285 g / eq, manufactured by Nippon Kayaku Co., Ltd.) 85 parts, dicyandiamide 4 parts, U-CAT3502T (aromatic dimethylurea, manufactured by San-Apro) 4 parts, FB-959 (spherical silica, particle size 25 μm, manufactured by Denki Kagaku Kogyo) 10 parts, H42M (aluminum hydroxide (particle size 1.5 μm) , Showa Denko Co., Ltd.) 20 parts were charged in a kneader and stirred and mixed at 75 ° C. for 1 hour to obtain a resin composition for comparison.

<Making a resin sheet>
[Example 1]
10.0 parts of the urethane-acrylic composite resin solution obtained in Production Example 1, 0.3 parts of jER630 as a cross-linking agent, 0.1 parts of C11Z-CN as a catalyst, and 2.4 parts of tetrahydrofuran are uniformly applied at room temperature. The mixture was stirred and mixed to obtain a resin composition. The obtained resin composition was applied onto a release film so that the thickness after drying was 300 μm, dried in a hot oven at 80 ° C. for 5 minutes, and the release film was removed after cooling to prepare a resin sheet. ..

[Examples 2 to 15 and Comparative Examples 1 to 5]
The same operations as in Example 1 were carried out except that the composition was changed to that shown in Table 2, to prepare resin sheets of Examples 2 to 15 and Comparative Examples 1 to 5. The resin sheet of Comparative Example 1 had a high viscosity, and it was difficult to remove the release film, so that the resin sheet could not be produced.

[Comparative Examples 6 to 7]
The same operations as in Example 1 were carried out except that the resin composition was changed to the resin composition shown in Table 2, and the resin sheets of Comparative Examples 6 to 7 were prepared.

<Evaluation of resin sheet>
The following tests were performed on the obtained resin sheet. The determination results are shown in Table 2. The following evaluation was not carried out for Comparative Example 1 in which the resin sheet could not be produced.

[Coating]
A chip having a length of 10 mm, a width of 10 mm, and a thickness of 2 mm was prepared on an FR-4 substrate. A resin sheet cut out to a length of 20 mm and a width of 20 mm is placed on it and softened in a heat oven at 80 ° C. for 1 minute to improve the coverage of the convex corners of the chip and the contact area between the side surface of the chip and the substrate. It was evaluated and judged according to the following criteria.

(Evaluation criteria for coverage of convex corners)
◯: The thickness of the covering part is 20 μm or more (good)
Δ: The thickness of the covering part is less than 20 μm, but there is no exposed tip (usable).
×: There is a part where the tip is exposed (cannot be used)

(Evaluation criteria for coverage of contact parts)
○: The contact part is completely covered with a resin sheet (good)
Δ: There is a slight gap between the resin sheet and the resin sheet (usable)
×: There is a gap between the resin sheet and the resin sheet (cannot be used)

[Flexibility]
The resin sheet was cut out into strips having a width of 5 mm to prepare test pieces for evaluation. Using this test piece, a tensile test was performed at a tensile speed of 50 mm / min, the elongation at break (%) was measured, and the determination was made according to the following criteria.

(Evaluation criteria for flexibility)
◯: Breaking elongation is 100% or more (good)
Δ: Breaking elongation is 50% or more and less than 100% (usable)
×: Breaking elongation is less than 50% (cannot be used)

[Heat-resistant]
The test piece after the evaluation of the covering property was allowed to stand in an environment of 120 ° C. for 500 hours, and then the covering thickness of the convex angle portion was evaluated. Based on the change in thickness before and after the heat resistance test, the judgment was made according to the following criteria. In addition, the heat resistance evaluation was not performed for the case where the covering property of the convex angle portion before the heat resistance test was judged to be ×.

(Evaluation criteria for heat resistance)
◯: Thickness change rate is less than 20% (good)
Δ: Thickness change rate is 20% or more and less than 35% (usable)
×: Thickness change rate is 35% or more (cannot be used)

The resin sheet of the present invention gave good results in terms of coating property, flexibility, and heat resistance. On the other hand, the adhesives of Comparative Examples had some or all inferior coating properties, flexibility, and heat resistance as compared with Examples.

Claims (5)

A resin sheet formed from a resin composition containing a urethane / acrylic composite resin and a cross-linking agent.
The urethane-acrylic composite resin is a resin in which a urethane unit (A) and a (meth) acrylic unit (B) are linked by a chain transfer agent residue.
The (meth) acrylic unit (B) is a structural unit derived from a crystalline (meth) acrylic monomer (b1) and a structural unit derived from a (meth) acrylic monomer (b2) having a crosslinkable group (however). (Excluding the structural unit derived from (b1)), and a resin sheet having. The resin sheet according to claim 1, wherein the crystalline (meth) acrylic monomer (b1) is a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms. The resin sheet according to claim 1 or 2, wherein the urethane / acrylic composite resin contains the urethane unit (A) in the range of 30 to 70% by mass based on the mass of the urethane / acrylic composite resin. The resin sheet according to any one of claims 1 to 3, which is used for sealing an electronic device. A laminate having the resin sheet according to any one of claims 1 to 4 and a release material.