JP5315923B2 - Acrylic elastomer and composition using the same - Google Patents

Description

  The present invention relates to an acrylic elastomer that can be suitably used for an electronic material and an acrylic elastomer composition using the acrylic elastomer.

  In recent years, with the reduction in size, weight, and speed of electronic devices, the density of semiconductor packages mounted on these electronic devices has increased, and the substrate on which the semiconductor package is mounted is also required to have higher density. . Furthermore, the miniaturization of wiring is further advanced on the substrate side.

  Conventionally, adhesives, heat resistance, electrical insulation, and long-term reliability are required for electronic materials such as adhesives for adhering semiconductor elements and mounting substrates on which various electronic components are mounted. As electronic materials that satisfy these requirements, compositions in which an epoxy resin and a curing agent are blended with synthetic rubbers such as acrylonitrile butadiene elastomers and acrylonitrile-containing acrylic elastomers are widely used (for example, see Patent Document 1).

  However, with the recent rapid increase in the density of semiconductor packages and mounting substrates and the miniaturization of wiring, stricter reliability is required for electronic materials. However, a composition using an acrylonitrile butadiene elastomer or an acrylonitrile-containing acrylic elastomer has been found to be inferior in electrical insulation under high temperature and high humidity. One cause of this is ionic impurities, and a technique for adding an ion scavenger (for example, see Patent Document 2) has been proposed to solve this problem, but it is sufficiently satisfactory in the field of fine wiring. The effect has not been obtained. An acrylic elastomer that does not contain acrylonitrile (see, for example, Patent Document 3) has also been proposed, but problems still remain with respect to the moisture absorption rate, etc., and sufficiently satisfactory long-term reliability has not been obtained.

JP-A-8-283535 Japanese Patent Laid-Open No. 2002-60716 Japanese Patent No. 3484161

  An object of the present invention is to provide an acrylic elastomer for electronic materials having excellent electrical insulation under high temperature and high humidity and excellent long-term reliability, and an acrylic elastomer composition using the same. To do.

As a result of intensive studies to solve the above problems, the present inventors have used a specific monomer as an essential component of an acrylonitrile-free acrylic elastomer, so that excellent electrical insulation under high temperature and high humidity It discovered that it became an acrylic elastomer which has property.
That is, the present invention includes a substituent having an alicyclic hydrocarbon having 5 to 22 carbon atoms,
A substituent having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group and an epoxy group is bonded to the polymer chain via a carbonyl bond. The present invention relates to acrylic elastomers.

  The present invention also relates to an acrylic elastomer containing at least the structures of the following general formulas (I) and (II) as repeating units.

（Ｘは、炭素数５〜２２の脂環式炭化水素基を含む置換基を示す。）

(X represents a substituent containing an alicyclic hydrocarbon group having 5 to 22 carbon atoms.)

（Ｙは、カルボキシル基、ヒドロキシル基、酸無水物基、アミノ基、アミド基及びエポキシ基からなる群より選ばれる少なくとも１種の官能基を含む置換基を示す。）

(Y represents a substituent containing at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group, and an epoxy group.)

The acrylic elastomer of the present invention is a methacrylic acid ester or acrylic acid ester having an alicyclic hydrocarbon group having 5 to 22 carbon atoms in the ester portion,
A functional group-containing monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group, and an epoxy group, and at least one carbon-carbon double bond; , And those obtained by polymerizing a monomer mixture containing

  In the present invention, as a monomer mixture, methacrylic acid ester or acrylic acid ester having 5 to 99.5 parts by mass of an alicyclic hydrocarbon group having 5 to 22 carbon atoms in the ester portion, and a functional group-containing monomer Preferably used is a monomer mixture containing 0.5 to 30 parts by mass and 0 to 90 parts by mass of monomers copolymerizable therewith so that the total mass of the monomers is 100 parts by mass. It is done.

  In the present invention, the alicyclic hydrocarbon group having 5 to 22 carbon atoms includes at least one selected from the group consisting of a cyclohexyl group, a norbornyl group, a tricyclodecanyl group, an isobornyl group, and an adamantyl group. Is preferred.

  The acrylic elastomer of the present invention preferably has a saturated moisture absorption rate of 0.6% or less.

  Furthermore, this invention relates to the acrylic elastomer composition for electronic materials containing the obtained acrylic elastomer and a solvent.

  The acrylic elastomer of the present invention has a low moisture absorption rate, hardly changes in volume resistance value under high temperature and high humidity, and is excellent in long-term reliability. Therefore, by using this elastomer for an electronic material, an electronic material with high electrical insulation and long-term reliability can be provided.

  The acrylic elastomer of the present invention is selected from the group consisting of a substituent having an alicyclic hydrocarbon having 5 to 22 carbon atoms, a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group, and an epoxy group. Each of the substituents having at least one functional group is bonded to the polymer chain via a carbonyl bond.

（Ｘは、炭素数５〜２２の脂環式炭化水素基を含む置換基を示す。） Further, the acrylic elastomer of the present invention is characterized in that it contains at least the structures of the following general formulas (I) and (II) as repeating units.

(X represents a substituent containing an alicyclic hydrocarbon group having 5 to 22 carbon atoms.)

（Ｙは、カルボキシル基、ヒドロキシル基、酸無水物基、アミノ基、アミド基及びエポキシ基からなる群より選ばれる少なくとも１種の官能基を含む置換基を示す。）

(Y represents a substituent containing at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group, and an epoxy group.)

The acrylic elastomer is a methacrylic acid ester or acrylic acid ester having an alicyclic hydrocarbon group having 5 to 22 carbon atoms in the ester portion,
A functional group-containing monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group, and an epoxy group, and at least one carbon-carbon double bond; It is obtained by polymerizing a monomer mixture containing.

As a monomer component used for polymerization in order to obtain an acrylic elastomer, a methacrylic acid ester or an acrylate ester having an alicyclic hydrocarbon group having 5 to 22 carbon atoms in the ester portion (hereinafter referred to as “alicyclic single monomer”). Also referred to as "body"). When the carbon number is less than 5, the chemical stability of the monomer is lacking, and the effect of reducing the moisture absorption rate of the resulting elastomer tends to be insufficient. If the carbon number exceeds 22, the Tg of the resulting elastomer tends to be high. The number of carbon atoms of these alicyclic monomers is more preferably 6-15, and most preferably 6-10. As the structure of the alicyclic monomer, a monomer containing at least one alicyclic hydrocarbon group selected from the group consisting of a cyclohexyl group, a norbornyl group, a tricyclodecanyl group, an isobornyl group, and an adamantyl group Is preferred.
When the above alicyclic monomer is used as the monomer component of the acrylic elastomer, the moisture absorption rate can be reduced efficiently, which is preferable from the viewpoint of resistance to electrolytic corrosion.

Specific examples of alicyclic monomers include cyclopentyl acrylate, cyclohexyl acrylate, methyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate, norbornyl acrylate, norbornyl methyl acrylate, phenyl norbornyl acrylate, and acrylic acid. Cyanonorbornyl, isobornyl acrylate, bornyl acrylate, menthyl acrylate, fentyl acrylate, adamantyl acrylate, dimethyladamantyl acrylate, tricyclo [5.2.1.0 ^2,6 ] dec-8-yl Tricyclo [5.2.1.0 ^2,6 ] deca-4-methyl acrylate, cyclodecyl acrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, trimethylcyclo methacrylate Hexyl, norbornyl methacrylate, norbornyl methyl methacrylate, cyano norbornyl methacrylate, phenyl norbornyl methacrylate, isobornyl methacrylate, bornyl methacrylate, menthyl methacrylate, fentyl methacrylate, adamantyl methacrylate, dimethyl methacrylate Adamantyl, tricyclo [5.2.1.0 ^2,6 ] dec-8-yl methacrylate, tricyclo [5.2.1.0 ^2,6 ] dec-4-methyl methacrylate, cyclodecyl methacrylate and the like. It is done. These may be used alone or in admixture of two or more. Moreover, it is also possible to mix and use the above methacrylic acid ester and acrylic acid ester as the alicyclic monomer.

Among these, in terms of low hygroscopicity, cyclohexyl acrylate, isobornyl acrylate, norbornyl acrylate, norbornyl acrylate, tricyclo [5.2.1.0 ^2,6 ] dec-8-yl acrylate, Tricyclo [5.2.1.0 ^2,6 ] deca-4-methyl acrylate, adamantyl acrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, norbornyl methacrylate, nor methacrylate Borunirumechiru, isobornyl methacrylate, bornyl methacrylate, menthyl methacrylate fenchyl, adamantyl methacrylate, dimethyladamantyl methacrylate tricyclo [5.2.1.0 ^2,6] dec - - yl, methacrylic acid tricyclo [5.2.1.0 ^2,6] dec-4-methyl, cyclodecyl methacrylate and methacrylic acid phenyl norbornyl are preferred.

Further, from the viewpoint of low hygroscopicity and adhesion, cyclohexyl acrylate, isobornyl acrylate, norbornyl acrylate, norbornyl acrylate, tricyclo [5.2.1.0 ^2,6 ] dec-8-yl acrylate, Particularly preferred are tricyclo [5.2.1.0 ^2,6 ] dec-4-methyl acrylate, adamantyl acrylate and the like.

Moreover, as a monomer component used for polymerization to obtain an acrylic elastomer, at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group, and an epoxy group in the molecule. A functional group-containing monomer having a seed functional group and at least one polymerizable carbon-carbon double bond is used.
Examples of the functional group-containing monomer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, and itaconic acid, acrylic acid-2-hydroxyethyl, methacrylic acid-2-hydroxyethyl, acrylic acid-2-hydroxypropyl, Hydroxyl group-containing monomers such as 2-hydroxypropyl methacrylate, N-methylolacrylamide, N-methylolmethacrylamide, etc., acid anhydride group-containing monomers such as maleic anhydride, amino groups such as diethylaminoethyl acrylate and diethylaminoethyl methacrylate Containing monomers, amide group-containing monomers such as acrylamide and methacrylamide, glycidyl acrylate, glycidyl methacrylate, glycidyl α-ethyl acrylate, glycidyl α-n-propyl acrylate, α-n-butyl acrylic acid Lysidyl, acrylic acid-3,4-epoxybutyl, methacrylic acid-3,4-epoxybutyl, acrylic acid-4,5-epoxypentyl, methacrylic acid-4,5-epoxypentyl, acrylic acid-6,7-epoxy Heptyl, methacrylic acid-6,7-epoxyheptyl, α-ethylacrylic acid-6,7-epoxyheptyl, acrylic acid-3-methyl-3,4-epoxybutyl, methacrylic acid-3-methyl-3,4- Epoxybutyl, 4-methyl-4,5-epoxypentyl acrylate, 4-methyl-4,5-epoxypentyl methacrylate, 5-methyl-5,6-epoxyhexyl acrylate, methacrylic acid-5 Methyl-5,6-epoxyhexyl, acrylic acid-β-methylglycidyl, methacrylic acid-β-methylglycidyl, α-ethyl Acrylic acid-β-methylglycidyl, 3-methyl-3,4-epoxybutyl acrylate, 3-methyl-3,4-epoxybutyl methacrylate, 4-methyl-4,5-epoxypentyl acrylate, Use of epoxy group-containing monomers such as 4-methyl-4,5-epoxypentyl methacrylate, 5-methyl-5,6-epoxyhexyl acrylate, and 5-methyl-5,6-epoxyhexyl methacrylate can do. These may be used alone or in admixture of two or more.

  Among these, an epoxy group-containing monomer is preferable in terms of storage stability, and glycidyl methacrylate is more preferable.

  In the present invention, as a monomer component used for polymerization to obtain an acrylic elastomer, in addition to the above alicyclic monomer and functional group-containing monomer, these monomers can be copolymerized. Other monomers can be used. The copolymerizable monomer is not particularly limited as long as it basically does not impair the low hygroscopicity, heat resistance and stability of the polymer. Specific examples include methyl acrylate, ethyl acrylate, N-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-acrylate Acrylates such as octyl, dodecyl acrylate, octadecyl acrylate, butoxyethyl acrylate, phenyl acrylate, benzyl acrylate, naphthyl acrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, methacryl N-Butyl acid, i-Butyl methacrylate, t-Butyl methacrylate Methacrylic acid esters such as pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, butoxyethyl methacrylate, phenyl methacrylate, naphthyl methacrylate, 4 -Vinylpyridine, 2-vinylpyridine, α-methylstyrene, α-ethylstyrene, α-fluorostyrene, α-chlorostyrene, α-bromostyrene, fluorostyrene, chlorostyrene, bromostyrene, methylstyrene, methoxystyrene, ( o-, m-, p-) aromatic vinyl compounds such as hydroxystyrene and styrene, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, N-methylmaleimide, N-ethylmaleimide, N-propyl N such as reimide, Ni-propylmaleimide, N-butylmaleimide, Ni-butylmaleimide, Nt-butylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide -Substituted maleimides and the like can be mentioned, among which methyl acrylate, ethyl acrylate, and n-butyl acrylate are more preferable. You may use these by 1 type (s) or 2 or more types.

  In the present invention, vinyl cyanide compounds (nitrile monomers) such as acrylonitrile and methacrylonitrile do not maintain electrical insulation under high temperature and high humidity, and become inferior in corrosion resistance. It is preferable not to use it.

  In the present invention, the mixing ratio of each monomer is 5 to 99.5 parts by mass of an alicyclic monomer, 0.5 to 30 parts by mass of a functional group-containing monomer, and a monomer copolymerizable with these. A ratio in which 0 to 90 parts by mass of the monomer is mixed so that the total mass part of the monomer is 100 parts by mass is preferable.

  The blending amount of the alicyclic monomer in the present invention is preferably 5 to 99.5 parts by mass, more preferably 10 to 80 parts by mass in terms of hygroscopicity. If the blending amount of the alicyclic monomer is less than 5 parts by mass, the hygroscopicity tends to increase, and if it exceeds 99.5 parts by mass, the mechanical strength tends to decrease.

  The compounding amount of the functional group-containing monomer in the present invention is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass. If the blending amount is less than 0.5 parts by mass, the adhesiveness tends to be low, and the strength tends to decrease. If the blending amount exceeds 30 parts by mass, a crosslinking reaction occurs when copolymerizing, and the storage stability is also increased. Tend to get worse.

  In the present invention, existing methods such as bulk polymerization, suspension polymerization, solution polymerization, precipitation polymerization, and emulsion polymerization can be applied as a polymerization method for producing the elastomer. Among these, the suspension polymerization method is most preferable in terms of cost.

  Suspension polymerization is performed in an aqueous medium and is performed by adding a suspending agent. Examples of the suspending agent include water-soluble polymers such as polyvinyl alcohol, methylcellulose, and polyacrylamide, and poorly soluble inorganic substances such as calcium phosphate and magnesium pyrophosphate. Among them, nonionic water-soluble polymers such as polyvinyl alcohol are preferable. . When an ionic water-soluble polymer or a hardly soluble inorganic substance is used, a large amount of ionic impurities tend to remain in the obtained elastomer. This water-soluble polymer is preferably used in an amount of 0.01 to 1 part by mass based on 100 parts by mass of the total amount of monomers.

  In carrying out the polymerization in the present invention, a radical polymerization initiator can be used. Examples of radical polymerization initiators include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxy-3 , 3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, and other organic peroxides; azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone-1-carbonitrile Azo compounds such as azodibenzoyl; water-soluble catalysts such as potassium persulfate and ammonium persulfate; and redox catalysts based on a combination of peroxide or persulfate and a reducing agent; Can also be used. It is preferable that a polymerization initiator is used in 0.01-10 mass parts with respect to 100 mass parts of total amounts of a monomer.

  In the present invention, the “monomer mixture” means an alicyclic monomer, a functional group-containing monomer and, if necessary, a monomer copolymerizable therewith.

  Further, as a chain transfer agent, a mercaptan compound, thioglycol, carbon tetrachloride, α-methylstyrene dimer or the like can be added as necessary.

  In the case of thermal polymerization, the polymerization temperature can be appropriately selected between 0-200 ° C, preferably 40-120 ° C.

  The elastomer produced as described above is not particularly limited in terms of its molecular weight, but the weight average molecular weight (polystyrene conversion by gel permeation chromatography) is in the range of 10,000 to 2,000,000. It is preferable that it is in the range of 100,000 to 1,500,000. If the weight average molecular weight is less than 10,000, the adhesiveness and strength tend to be low, and if it exceeds 2,000,000, the solubility in a solvent tends to decrease and the workability tends to deteriorate.

The acrylic elastomer of the present invention preferably has a saturated moisture absorption rate of 0.6% or less. When the saturated moisture absorption is 0.6% or less, a decrease in electrical insulation under high temperature and high humidity can be suppressed. In order to adjust the saturated moisture absorption to 0.6% or less, it can be achieved by appropriately selecting each monomer component and adjusting the blending amount.
In the present invention, the saturated moisture absorption rate is a value calculated by the following equation by measuring the mass of the acrylic elastomer and absorbing moisture until the mass becomes constant at room temperature (20 to 30 ° C.).

  The acrylic elastomer of the present invention preferably has a Tg of 15 ° C. or less, more preferably 10 ° C. or less, and further preferably 5 ° C. or less. When Tg increases, flexibility and adhesion tend to decrease. The Tg of the obtained elastomer can be designed by appropriately adjusting the monomer composition.

  The acrylic elastomer of the present invention can be dissolved in a solvent and provided as a solution-like acrylic elastomer composition for an electronic material such as a semiconductor device or a wiring board.

  As the solvent, general organic solvents such as toluene, xylene, methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexane, ethyl acetate, butyl acetate, tetrahydrofuran and the like can be used. The amount used is preferably such that the content (solid content concentration) of the acrylic elastomer is 5 to 40% by mass, more preferably 10 to 30% by mass relative to the total amount with the acrylic elastomer. .

  The acrylic elastomer for electronic materials of the present invention can be mixed with an epoxy resin and further with an epoxy resin curing agent as necessary to form a polymer alloy, which can be used as an electronic material. These epoxy resins and epoxy resin curing agents are not particularly limited, and commercially available materials can be used. Moreover, in order to improve reactivity, adhesiveness, and intensity | strength, materials, such as a filler, a hardening accelerator, a silane coupling agent, and various fillers, can be used together. The electronic material may be in the form of a film, paste, or solution.

  There is no restriction | limiting in particular in the mixing ratio of an elastomer and an epoxy resin, For example, it can be used in the ratio of 10 / 90-90 / 10 by the former / latter (mass ratio).

  The epoxy resin is not particularly limited as long as it cures and exhibits an adhesive action. In general, an epoxy resin having two or more functions (containing two or more epoxy groups in one molecule) can be used. Examples of the bifunctional epoxy resin include bisphenol A type or bisphenol F type epoxy resin. In addition, a polyfunctional epoxy resin having a trifunctional or higher functionality (containing 3 or more epoxy groups in one molecule) may be used. Examples of the trifunctional or higher functional epoxy resin include a phenol novolac type epoxy resin and a cresol novolak type epoxy resin. Resins and the like are exemplified.

  As the curing agent for the epoxy resin, those usually used as a curing agent for the epoxy resin can be used, and two or more amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, and phenolic hydroxyl groups in one molecule. Bisphenol A, bisphenol F, bisphenol S, a phenol resin, etc. which are the compounds which have can be used. From the viewpoint of excellent electric corrosion resistance at the time of moisture absorption, it is preferable to use a phenol novolac resin, a bisphenol novolac resin, a cresol novolac resin, or the like.

  In general, the curing agent is preferably used so that the group that reacts with the epoxy group of the curing agent is 0.6 to 1.4 equivalent to 1 equivalent of the epoxy group of the epoxy resin. It is more preferable to use it so that it may become 2 equivalent. When the amount of the curing agent is too small or too large, the heat resistance tends to decrease.

  Furthermore, a hardening accelerator can also be used with a hardening agent, and various imidazoles etc. are mentioned as a hardening accelerator. When the curing accelerator is used, the amount is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass with respect to 100 parts by mass in total of the epoxy resin and the curing agent. If it is less than 0.1 parts by mass, the curing rate tends to be slow, and if it exceeds 20 parts by mass, the pot life tends to be short.

  There is no restriction | limiting in particular in the method in the case of making it into a film form, For example, the varnish of the said semiconductor device adhesive can be apply | coated and dried using a various coating apparatus on a base film.

  The acrylic elastomer for electronic materials of the present invention is preferably used for electronic materials such as adhesives for semiconductors such as film adhesives, substrate materials for flexible wiring boards and adhesives used therefor, and adhesive films for circuit connection.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the scope of the present invention is not limited thereto.

Example 1
295 g of tricyclo [5.2.1.0 ^2,6 ] dec-8-yl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-513A), 288 g of ethyl acrylate (EA), 387 g of butyl acrylate (BA) 30 g of glycidyl methacrylate (GMA) was mixed, and 2 g of lauroyl peroxide and 0.16 g (0.016%) of n-octyl mercaptan as a chain transfer agent were further dissolved in the resulting monomer mixture. It was.

  Add 0.04g of polyvinyl alcohol and 2000g of ion-exchanged water as a suspending agent to a 5L autoclave equipped with a stirrer and a condenser and add the above mixture while stirring, stirring at 250rpm, and at 60 ° C under a nitrogen atmosphere. Polymerization was carried out for 2 hours and then at 100 ° C. for 1 hour to obtain resin particles (polymerization rate was 99% by weight method). The resin particles were washed with water, dehydrated and dried, and dissolved in methyl isobutyl ketone so that the heating residue was 25% by mass to prepare a resin varnish. Next, 200 parts by mass of resin varnish, 40 parts by mass of bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., Epicoat 828), 40 parts by mass of phenol resin (manufactured by Dainippon Ink & Chemicals, Inc., LF2882), curing A mixed solution consisting of 0.5 parts by mass of 1-cyanoethyl-2-phenylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., Curesol 2PZ-CN) as an accelerator was applied onto an aluminum plate having a thickness of 500 μm, and the temperature was 160 ° C. It dried for 1 hour and produced the film with a film thickness of 50 micrometers.

(Example 2)
A film was produced in the same manner as in Example 1 except that the monomer mixture having the composition ratio shown in Table 1 was used and the chain transfer agent was changed to 0.54 g (0.054%).

(Example 3)
A film was prepared in the same manner as in Example 1 except that the monomer mixture having the composition ratio shown in Table 1 was used and the chain transfer agent was changed to 0.90 g (0.090%).

Example 4
A film was produced in the same manner as in Example 2 except that the monomer mixture having the composition ratio shown in Table 1 was used.

(Example 5)
A film was produced in the same manner as in Example 2 except that the monomer mixture having the composition ratio shown in Table 1 was used.

(Example 6)
A film was produced in the same manner as in Example 2 except that the monomer mixture having the composition ratio shown in Table 1 was used.

(Example 7)
A film was produced in the same manner as in Example 2 except that cyclohexyl acrylate was used as the alicyclic monomer and a monomer mixture having the composition ratio shown in Table 1 was used.

(Example 8)
A film was produced in the same manner as in Example 2 except that isobornyl acrylate was used as the alicyclic monomer and a monomer mixture having the composition ratio shown in Table 1 was used.

( Reference Example 9)
A film was produced in the same manner as in Example 2 except that acrylic acid was used as the functional group-containing monomer and a monomer mixture having a composition ratio shown in Table 1 was used.

( Reference Example 10)
A film was produced in the same manner as in Example 2 except that hydroxyethyl acrylate was used as the functional group-containing monomer and a monomer mixture having the composition ratio shown in Table 1 was used.

(Comparative Example 1)
A film was prepared in the same manner as in Example 1 except that commercially available acrylonitrile was used and the composition ratios shown in Table 1 were used.

The molecular weight, glass transition temperature (Tg), moisture absorption rate, volume resistance value, etc. of the resins and films of Examples 1 to 8, Reference Examples 9 to 10, and Comparative Example 1 were measured and shown in Table 1. In addition, each evaluation was performed using the method shown below.

(1) Weight average molecular weight It measured using gel permeation chromatography (eluent: THF, column: Gelpack GL-A100M, polystyrene conversion).

(2) Glass transition temperature (Tg)
Measurement was performed in a range of −60 to 20 ° C. (heating rate: 10 ° C./min) under a nitrogen atmosphere using DSC (manufactured by SII Nanotechnology, Inc., DSC-6200 type).

(3) Moisture absorption The mass after drying of the resin was measured, and moisture was absorbed until the mass became constant at room temperature, and the moisture absorption was calculated by the following formula.

(4) Volume resistance value The volume resistance value of the film was measured using a high resistance meter (manufactured by Hewlett-Packard, 4329A).
(5) Resistance to electric corrosion The produced film was allowed to stand at 85 ° C. and 85% humidity for 24 hours, and the volume resistance value was measured.

Details of the monomers shown in the table are as follows.
FA-513A: tricyclo [5.2.1.0 ^2,6 ] deca-8-yl acrylate (manufactured by Hitachi Chemical Co., Ltd.),
CHA: cyclohexyl acrylate IBOA: isobornyl acrylate EA: ethyl acrylate,
BA: butyl acrylate,
GMA: Glycidyl methacrylate HEA: Hydroxyethyl acrylate

In Examples 1 to 8 and Reference Examples 9 to 10 using the alicyclic monomer and the functional group-containing monomer, elastomers having a low moisture absorption rate are obtained. By using these elastomers, the volume resistance value and A film with high resistance to electric corrosion was obtained. On the other hand, the elastomer of Comparative Example 1 not using an alicyclic monomer had a high moisture absorption rate, and the obtained film was inferior in electric corrosion resistance.

Claims (3)

An acrylic elastomer in which a substituent having an alicyclic hydrocarbon having 5 to 22 carbon atoms and a substituent having an epoxy group are each bonded to a polymer chain via a carbonyl bond;
The repeating unit contains at least the structures of the following general formulas (I) and (II),
5-99.5 parts by mass of a methacrylic acid ester or an acrylate ester having an alicyclic hydrocarbon group having 5 to 22 carbon atoms in the ester portion;
D epoxy group-containing monomers over 0. 5 to 30 parts by mass;
It is obtained by polymerizing a monomer mixture containing 0 to 90 parts by mass of monomers copolymerizable with these so that the total mass is 100 parts by mass,
Before SL epoxy group-containing monomer, glycidyl acrylate, glycidyl methacrylate, alpha-ethyl acrylate glycidyl, alpha-n-propyl acrylate glycidyl, alpha-n-butyl acrylate glycidyl, 3,4-epoxy butyl acrylate Methacrylic acid-3,4-epoxybutyl, acrylic acid-4,5-epoxypentyl, methacrylic acid-4,5-epoxypentyl, acrylic acid-6,7-epoxyheptyl, methacrylic acid-6,7-epoxyheptyl , Α-ethylacrylic acid-6,7-epoxyheptyl, 3-methyl-3,4-epoxybutyl acrylate, 3-methyl-3,4-epoxybutyl methacrylate, 4-methyl-4 acrylic acid , 5-epoxypentyl, methacrylic acid-4-methyl-4,5-epoxypentyl, acrylic -5-methyl-5,6-epoxyhexyl, methacrylic acid-5-methyl-5,6-epoxyhexyl, acrylic acid-β-methylglycidyl, methacrylic acid-β-methylglycidyl, α-ethylacrylic acid-β- Methyl glycidyl, 3-methyl-3,4-epoxybutyl acrylate, 3-methyl-3,4-epoxybutyl methacrylate, 4-methyl-4,5-epoxypentyl acrylate, methacrylic acid-4- methyl-4,5-epoxy pentyl state, and are any one or more acrylic acid-5-methyl-5,6-epoxy hexyl and methacrylic acid methyl-5,6-epoxy-hexyl, and,
An acrylic elastomer, wherein the alicyclic hydrocarbon group having 5 to 22 carbon atoms includes at least one selected from the group consisting of a cyclohexyl group, a norbornyl group, a tricyclodecanyl group, an isobornyl group, and an adamantyl group .

(X represents a substituent containing an alicyclic hydrocarbon group having 5 to 22 carbon atoms.)

(Y represents a substituent containing a d epoxy group.) The acrylic elastomer according to claim 1 , wherein the saturated moisture absorption is 0.6% or less. An acrylic elastomer composition comprising the acrylic elastomer according to claim 1 or 2 and a solvent.