JP3022980B2 - Thermosetting film adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention is particularly excellent in storage stability and adhesive strength in a wide temperature range, and can be peeled off by heating once connected to a predetermined temperature or more. The present invention relates to a novel film adhesive.

(Prior Art) With the recent miniaturization and thinning of electronic devices, the necessity of temporarily bonding components at the time of fixing micro components or connecting micro circuits has been increasing. That is, while it is necessary to firmly adhere and fix, it is required to be able to peel off without breaking or damaging the equipment as necessary.

Conventionally, such film adhesives are roughly classified into a thermoplastic type and a thermosetting type, and recently, an epoxy resin type thermosetting type having excellent reliability has been widely used. However, many of these are two-part,
Those having poor storage stability, or those having excellent storage stability require a long time or high temperature for curing, and those which can be cured at low temperature for a short time have poor storage stability.

In order to solve these problems, an adduct obtained by reacting an imidazole derivative or an amine derivative with an epoxy resin, and a curing agent obtained by microencapsulating them are commercially available. However, all of these are inferior in solvent resistance, and there are great restrictions when using a solvent. If a solvent is used, the types of solvents that can be used for film formation are limited, and workability is required such that the film must be formed in a short time after mixing adjustment and the solvent must be removed promptly. There is a problem.

In addition, as described above, there are many demands for peeling off a connected member without breaking or damaging the connected member, but most of the thermosetting type have high adhesive strength,
Although it has the advantage of high reliability, there is a problem that it cannot be adapted to such requirements.

(Problems to be Solved by the Invention) When producing a thermosetting film adhesive, a film forming agent and other components for improving various properties are dissolved and mixed with a solvent to form a film. However, when using a commercially available microencapsulated curing agent or amine adduct that can be cured at a low temperature and in a short time as described above, a polar solvent cannot be particularly used.

In addition, a demand for peeling the connection once without damaging or damaging the member to be connected is impossible with a thermosetting resin such as an epoxy resin alone. In order to provide performance that can meet such demands, a reactive thermoplastic elastomer is mixed, but for this purpose, a solvent must be used.

The present invention solves these contradictory problems, and has excellent storage stability and adhesive strength in a wide temperature range (−30 to 100 ° C.), and heats once connected to a predetermined temperature or higher. It is an object of the present invention to provide a thermosetting film-like adhesive which can be peeled off.

(Means for Solving the Problems) The present invention is characterized in that a film is formed from a mixture containing a reactive elastomer, an epoxy resin, a solvent for dissolving them, an imidazole derivative epoxy compound, and a non-reactive diluent. Is an anisotropic conductive film.

The reactive elastomer used in the present invention includes carboxyl group-containing styrene-butadiene copolymer, carboxyl group-containing styrene-isoprene copolymer, carboxyl group-containing styrene-butadiene saturated copolymer, and carboxyl group-containing styrene-isoprene saturated copolymer. Polymer, carboxyl group-containing styrene-ethylene-butene-styrene copolymer, carboxyl group-containing styrene-ethylene-
Butene-styrene saturated copolymer, carboxylic acid-terminated acrylonitrile-butadiene copolymer, carboxylic acid-modified acrylonitrile-butadiene copolymer, hydrogenated carboxylic acid-modified acrylonitrile-butadiene copolymer, carboxylic acid-modified acrylic rubber, butyral resin, urethane Resin, amino acid-modified polyol resin, amino group-modified phenoxy resin, hydroxy-terminated saturated copolyester resin, carboxyl-terminated saturated copolyester resin, and the like. Preferably, it is a styrene-ethylene-butene-styrene saturated copolymer containing a carboxyl group.

Further, as the epoxy resin in the present invention, an epoxy resin having at least two or more epoxy groups in one molecule is used. Specific examples include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, cresol novolac epoxy resin, diglycidyl dimer acid, diglycidyl phthalate, and tetrabromobisphenol. A diglycidyl ether, bisphenol hexafluoroacetone diglycidyl ether, triglycidyl isocyanurate, tetraglycidyl diaminodiphenylmethane and the like are used, and these are used alone or in combination of two or more. Preferred is a bisphenol A type epoxy resin.

As the solvent, any solvent that can completely dissolve the reactive elastomer and the epoxy resin as described above can be used. Specific examples include acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, xylene, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, ethyl acetate, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, diacetone ether, methyl cellosolve acetate. , Ethyl cellosolve acetate, dimethylformamide, dimethylacetamide and the like, and these can be used alone or as a mixture of two or more.

The imidazole derivative epoxy compound is an adduct of the imidazole compound and the epoxy compound. Examples of the imidazole compound include imidazole, 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4.
-Methylimidazole, 2-phenylimidazole, 2
-Phenyl-4-methylimidazole, 1-benzyl-
2-methylimidazole, 1-benzyl-2-ethylimidazole, 1-benzyl-2-ethyl-5-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5- Dihydroxymethylimidazole and the like. Examples of the epoxy compound include glycidyl ether type epoxy resins such as bisphenol A, phenol novolak, bisphenol F, and brominated bisphenol A;
Examples include dimer acid diglycidyl ester and phthalic acid diglycidyl ester. Preferably, it is a bisphenol A type epoxy resin.

The reaction product of the above-mentioned imidazole derivative and epoxy compound is commercially available as a fine powder. Furthermore, there are also those which are mixed with an isocyanate compound to increase the storage stability and those which are microencapsulated. Among them, it is preferable to use microencapsulated one. However, these have poor solvent resistance as described above.
Such a disadvantage is that the non-reactive diluent is used in an amount of 5 to 30% based on the reaction product of the imidazole derivative and the epoxy compound.
It can be easily improved simply by mixing. In this way, when producing a thermosetting film adhesive, it is possible to form a film by dissolving and mixing a compound for improving various properties with a solvent, including a film forming material,
A commercially available microencapsulated curing agent that can be cured in a short time at a low temperature or an amine adduct can be used as a curing agent in a composition prepared using a polar solvent. If the non-reactive diluent used is less than 5%, the effect on storage stability is poor,
On the other hand, if it is 30% or more, various physical properties of the cured product, for example, the adhesive strength and the degree of curing are remarkably deteriorated.

When a reactive diluent was used, no effect on storage stability was observed.

Non-reactive diluents include phthalate esters such as dibutyl phthalate, dioctyl phthalate, heptyl nonyl phthalate, ditridecyl phthalate, diethyl phthalate, dimethyl phthalate, and butyl benzyl phthalate; tributyl phosphate; Phosphate esters such as phenyl and diphenylmonocresyl phosphate, and fatty acid esters such as butyl stearate, methoxyethyl oleate, and glycerin triheptanoate are exemplified. Preferably, it is dioctyl phthalate.

 Hereinafter, the present invention will be described specifically with reference to examples.

(Example 1) As a reactive elastomer, a carboxyl group-containing styrene-ethylene-butene-styrene saturated copolymer “Tuftec M1913” (manufactured by Asahi Kasei Corporation) was added to a mixed solvent of MEK (methyl ethyl ketone) and toluene (1: 2). Dissolved and adjusted as a 50% solution. To 60 parts by weight of this solution, 50 parts by weight of a bisphenol A type epoxy resin “Epicoat 828” (manufactured by Yuka Shell Epoxy) was mixed. Separately, epoxy resin "Epicoat 1004" (manufactured by Yuka Shell Epoxy)
100 parts by weight were dissolved in 50 parts by weight of MEK, added to the above reactive elastomer solution, and uniformly mixed. In this mixed solution,
12.5 parts by weight of dioctyl phthalate as a non-reactive diluent and 50 parts by weight of HX3742 (manufactured by Asahi Kasei Corporation) as a reaction product of an imidazole derivative and an epoxy compound were mixed.

This was applied to a release film (polyethylene terephthalate) so that the thickness after drying was 15 μm,
For 1 hour, and then peeled from the release film to obtain a film adhesive.

(Example 2) Further, in order to see the characteristics when a solvent having an increased polarity was used, 30 parts by weight of a carboxyl group-containing styrene-ethylene-butene-styrene saturated copolymer “Tuftec M1913” was mixed with DMF (dimethylformamide). ) Dissolved in 30 parts by weight, mixed with an epoxy resin, a non-reactive diluent, and a reaction product of an imidazole derivative and an epoxy compound in the same manner as in Example 1, and applied and dried to form a film adhesive. I got

Example 3 As a reaction product of an imidazole derivative and an epoxy compound, a powder obtained by reacting a glycidyl ether type epoxy resin of bisphenol A with 2-methylimidazole was crushed to a particle size of 5 μm or less. A film-like adhesive was obtained in the same manner as in Example 2 except that parts by weight were used.

(Example 4) As a reactive elastomer, a carboxylic acid-modified acrylonitrile-butadiene copolymer (manufactured by Nippon Synthetic Rubber Co., Ltd.) 30
A film-like adhesive was obtained in the same manner as in Example 1, except that parts by weight were dissolved in a mixed solvent of 30 parts by weight of DMF and 5 parts by weight of MEK.

(Comparative Example 1) A film-like adhesive was formed in the same manner as in Example 1 except that aliphatic diglycidyl ether was used as a reactive diluent instead of the non-reactive diluent. It was very bad.

The film adhesives obtained in these Examples and Comparative Examples were subjected to storage stability, adhesion, and repairability tests. The results are shown in Table 1.

The adhesion was tested by a 90 ° peel test. The adherend was 50 μm plated with 5 μm nickel.
Copper foil and a glass epoxy laminate were used.

For evaluation of repairability, the test piece once connected by thermocompression bonding was heated to 165 ° C. and peeled off, and it was observed whether or not the connected member could be peeled off without damage.

As an evaluation of storage stability, after leaving at room temperature and 40 ° C. for one month, it was confirmed that the material was melted on a hot plate at 120 ° C., and further, whether the adherend could be adhered under predetermined conditions. And measure the adhesive strength.
% Or more, it was evaluated as ○.

(Effects of the Invention) As described above, according to the present invention, when producing a thermosetting film-type adhesive, various types of film forming agents, including film forming agents, can be used without being limited by the type of solvent. It is possible to form a film by dissolving and mixing a compound for improving performance. In addition, it can be adhered in a short time, and particularly excellent in storage stability and adhesive strength in a wide range of temperatures (−30 to 100 ° C.), and can be peeled off by heating once connected to a predetermined temperature or higher. A thermosetting film adhesive can be provided.

Claims (1)

(57) [Claims] 1. A film adhesive characterized by being formed from a mixture containing a reactive elastomer, an epoxy resin, a solvent for dissolving them, an imidazole derivative epoxy compound and a non-reactive diluent.