JPH11106483A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having a sufficient pot life, rapidly curable at a low heating temperature, capable of developing a strong bond strength, useful as an adhesive, a sealing agent, etc., by including an epoxy resin and a specific polythiol. SOLUTION: This composition comprises (A) an epoxy resin (e.g. one having 43-1,000 epoxy equivalent) such as a bisphenol type epoxy resin and (B) a polythiol containing three or more mercapto groups in one molecule and consisting only of carbon atoms, sulfur atoms and hydrogen atoms [e.g. a compound of the formula; R-(SH)m ((m) is 3-10; R is a 3-18C hydrocarbon (m)- functional group) having >=150 deg.C boiling point]. Preferably the composition has the equivalent ratio of the total amount of the mercapto groups of the component B/the total amount of the epoxy groups of the component A of 0.5/1.5 to 1.5/0.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an epoxy resin composition.

[0002]

2. Description of the Related Art Epoxy resin compositions using a polythiol as a curing agent and an amine as a curing accelerator are known as -20%.
It is known as a low-temperature fast-curing epoxy resin composition that can be cured even at a temperature of from 0 ° C to 0 ° C, and is widely used in adhesives, sealing agents, casting, and the like.

However, such an epoxy resin composition has a drawback that the pot life is usually very short, from several seconds to several hours after mixing, so that sufficient time cannot be taken for mixing, defoaming, and coating. In addition, the worker has to prepare the composition each time, so the workability is poor, and the surplus composition cannot be stored and must be discarded, which leads to resource saving and environmental problems. Was also not preferred.

Therefore, development of a polythiol-based epoxy resin having a sufficient pot life and improved workability has been desired. However, those using a commercially available thiol compound, amine-based curing accelerator or solid dispersion type latent curing accelerator for the epoxy resin generally have poor storage stability,
It was impossible to extend the pot life sufficiently.

[0005]

The object of the present invention is to provide an epoxy resin composition which has a sufficient pot life, is rapidly cured at a relatively low heating temperature, and has a strong adhesive strength. It is.

[0006]

The present invention relates to (A) an epoxy resin and (B) a polythiol having three or more mercapto groups in one molecule and comprising only carbon, sulfur and hydrogen atoms. And an epoxy resin composition comprising:

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the epoxy resin (A) is not particularly limited as long as it has two or more epoxy groups in a molecule, and a known resin can be used. Examples of such an epoxy resin (A) include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol epoxy resins such as bisphenol A / bisphenol F copolymer epoxy resins, cresol novolak epoxy resins, and phenol novolaks. Novolak epoxy resins such as epoxy resins, biphenyl diglycidyl ether, triglycidyl isocyanurate, polyglycidyl methacrylate, and copolymers of glycidyl methacrylate with a vinyl monomer copolymerizable therewith. These are used alone or in combination of two or more. Among these, bisphenol-type epoxy resins are preferred, because grades having different molecular weights are widely available as compared with other various epoxy compounds, and adhesiveness, reactivity and the like can be arbitrarily set.

The epoxy equivalent of the epoxy resin (A) used in the present invention is preferably 43 to 1,000, more preferably 50 to 800, and particularly preferably 73 to 600. If the epoxy equivalent is less than 43 or more than 1000, the adhesive strength tends to decrease when connecting electrodes described later. These (A) epoxy resins have impurity ions (Na ⁺ , Cl ^−).
Etc.) or a high-purity product in which hydrolyzable chlorine or the like is reduced to 300 ppm or less is preferable for preventing electron migration.

The polythiol (B) used in the present invention comprises 1
There is no particular limitation as long as the compound has three or more mercapto groups in the molecule and is composed of only carbon, sulfur and hydrogen atoms. When the number of mercapto groups in one molecule is two or less, only an adhesive having a low softening point can be obtained, and the pot life is reduced, and hydrogen sulfide is generated during curing, and the cured product becomes a foam. (B) When the polythiol has a hydroxyl group and an ester bond, it contains an oxygen atom as a constituent atom.
(B) The polythiol must not have a hydroxyl group or an ester bond.

As the polythiol (B),
For example, the following general formula (I)

Embedded image (Wherein, R represents an m-valent hydrocarbon group having 3 to 18 carbon atoms, and m is an integer of 3 to 10). Here, the m-valent hydrocarbon group having 3 to 18 carbon atoms may include a linear chain hydrocarbon group, a chain hydrocarbon group having a branched carbon chain, and two or more rings. Alicyclic hydrocarbon group, aromatic hydrocarbon group optionally containing two or more rings, group in which one or more chain carbon skeleton is bonded to alicyclic hydrocarbon, one or more chains in aromatic hydrocarbon And a group in which one or more alicyclic hydrocarbons are bonded to one or more aromatic hydrocarbons.

The compound represented by the general formula (I) includes
Specifically, alkyl mercaptans such as pentaerythrithiol and trimercaptomethylpropane, 1,3,5-
Aromatic mercaptans such as trimercaptobenzene, 1,
And aromatic alkyl mercaptans such as 3,5-trimercaptomethylbenzene. In addition, if the polythiol evaporates by heating during curing, the reaction equivalent to epoxy cannot be maintained. Therefore, the boiling point is desirably 150 ° C. or higher.

The value obtained by dividing the molecular weight of the polythiol (B) used in the present invention by the number of functional groups (SH equivalent) is from 36 to 1000.
Is preferable, 36 to 800 are more preferable, and 36 to 60 are preferable.
0 is particularly preferred. If the SH equivalent is less than 36 or more than 1000, the adhesive strength tends to decrease when connecting electrodes described later.

The amount of (B) polythiol used is 0.5 / 1. (Equivalent ratio) of (A) epoxy resin to (B) total amount of mercapto groups / total amount of epoxy groups of polythiol.
It is preferable that the ratio be 5 to 1.5 / 0.5, and it is more preferable that the ratio be 0.8 / 1.2 to 1.2 / 0.8. This ratio is 0.5 /
If the ratio is less than 1.5 or exceeds 1.5 / 0.5, a large amount of unreacted epoxy groups or mercapto groups will remain in the connector after the curing reaction, and the adhesive strength tends to decrease. . The form of the polythiol (B) is preferably liquid because it has higher operability than solid in consideration of the miscibility with other components, but is not limited to liquid.

The epoxy resin composition of the present invention may optionally contain (C) a curing accelerator. Such a curing accelerator (C) is not particularly limited as long as it exhibits an activity of accelerating the reaction between epoxy groups or between an epoxy group and a mercapto group. Examples thereof include 2-methylimidazole, 2-ethylimidazole, Alkylimidazole compounds such as 2-propylimidazole, arylimidazole compounds such as phenylimidazole and naphthylimidazole, aminoalkylimidazole compounds such as 2-aminoethylimidazole and 2-aminopropylimidazole, adipic dihydrazide, eicosan diacid dihydrazide; Hydrazide compounds such as 11-octadecadieene-1,18-dicarbohydrazide, 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin, amine imide, polyamine, dicyandiamide,
Tertiary phosphines, quaternary ammonium salts, quaternary phosphonium salts and the like. These are used alone or in combination of two or more.

These (C) curing accelerators may be microencapsulated by coating with a polymer substance such as polyurethane or polyester, a metal thin film such as Ni or Cu, or an inorganic substance such as calcium silicate, or the like. May be made into an adduct by reacting with an epoxy resin described above, and such an adduct is preferable in view of extending the pot life.

By these (C) curing accelerators, (B)
The activity of the polythiol is catalytically enhanced, quick curing is obtained, and the necessary adhesive strength can be obtained even when the heating temperature during curing is lowered, and the conductive part due to thermal expansion of the connected material is obtained. The displacement can be minimized.

When the curing accelerator (C) is used, the amount thereof is preferably 0.01 to 200 parts by weight, preferably 0.1 to 200 parts by weight, per 100 parts by weight of the epoxy resin (A).
To 100 parts by weight, more preferably 0.5 to 5 parts by weight.
It is particularly preferable to use 0 parts by weight. This amount is 0.0
If the amount is less than 1 part by weight, the effect of promoting the curing tends to be insufficient, and if it exceeds 200 parts by weight, the compatibility tends to decrease.

The epoxy resin composition of the present invention is further obtained by reacting bisphenol A and / or bisphenol F with epichlorohydrin and has the following general formula (II):

Embedded image (Wherein R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and n represents a positive integer). (E) Phenoxy resin which is a high molecular weight compound having a structure represented by It may be added.

Examples of the phenoxy resin (E) used as required include general-purpose phenoxy resins such as bisphenol A phenoxy resin, bisphenol F phenoxy resin, bisphenol A and bisphenol F copolymerization phenoxy resin. Such a phenoxy resin is similar in structure to an epoxy resin and therefore has good compatibility and good adhesion. The larger the molecular weight, the more easily the film-forming property can be obtained, and the melt viscosity which affects the fluidity at the time of connection can be set in a wide range. (E) The phenoxy resin has a weight average molecular weight of 10,000 to 150,000.
0, of which 10,000 to 80,0
00 is preferred. If this value is less than 10,000, the film-forming properties tend to be poor, and
If it exceeds, the compatibility with other components tends to deteriorate.
When (E) a phenoxy resin is used, it is preferable to use 20 to 320 parts by weight based on 100 parts by weight of the epoxy resin. When this amount is less than 20 parts by weight or more than 320 parts by weight, the film-forming property tends to decrease.

The epoxy resin composition of the present invention may optionally contain additives such as an adhesion improver such as a coupling agent and a leveling agent.

The epoxy resin composition of the present invention can be used by adding a solvent or the like, if necessary. A solution containing the solvent or the like is applied onto a peelable substrate such as a fluororesin film or release paper. Alternatively, a substrate such as a nonwoven fabric is impregnated with the solution and placed on a releasable substrate, and dried at an activation temperature or lower of a curing accelerator used as needed, and a solvent or the like is removed to form a film. It can be used in the form of a film. Use in the form of a film is more convenient in terms of handling properties and the like. The solvent is not particularly limited and a known solvent can be used, but a mixed solvent of an aromatic hydrocarbon-based solvent such as toluene and an oxygen-containing solvent including acetic esters such as ethyl acetate is soluble. It is preferred in terms of. Here, the SP value of the oxygen-containing solvent is preferably in the range of 8.1 to 10.7 from the viewpoint of protection of the curing accelerator used as necessary.
Further, the boiling point of the solvent is preferably 150 ° C. or less,
C is more preferable, and 70 to 80 C is particularly preferable. When the boiling point exceeds 150 ° C., a high temperature is required for drying and the temperature is close to the activation temperature of the curing accelerator, so that the pot life tends to decrease, and at a low temperature, the workability during drying tends to decrease.
When a solvent is used, the amount used is such that the solid content of the solution is 1%.
Preferably, the amount is from 0 to 90% by weight.

The epoxy resin composition of the present invention is useful for adhesion and connection. Since the epoxy resin composition of the present invention can be bonded and connected at a relatively low temperature, thermal stress during bonding and connection is small, reliability after bonding and connection can be significantly improved, and a large margin can be obtained. In addition, the efficiency of the bonding and connection work is improved, and the yield is also improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. Example 1 As an epoxy resin, 50 g of bisphenol A type epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 184) was dissolved in a mixed solvent of toluene / ethyl acetate = 50/50 by weight ratio. do it,
This was used as a solution having a solid content of 40% by weight. As the polythiol, pentaerythrithiol (SH equivalent: 50)
Was used in an amount of 13.5 g. As a curing accelerator, Novacure 3941 (a master obtained by dispersing a microcapsule-type curing accelerator having an imidazole-modified core as a nucleus and covering the surface with polyurethane and having an average particle size of 5 μm in a liquid bisphenol F type epoxy resin). 2.0 g of a batch-type curing accelerator (trade name, manufactured by Asahi Kasei Corporation) was used.

As the phenoxy resin, 50 g of a bisphenol A / F copolymerized phenoxy resin (average molecular weight: 20,000) was prepared from bisphenol A, bisphenol F (1/1) and epichlorohydrin by a general method. This is weight ratio of toluene (boiling point 110.6 ° C,
It was dissolved in a mixed solvent of (SP value: 8.90) / ethyl acetate (boiling point: 77.1, SP value: 9.10) = 50/50 to obtain a solution having a solid content of 40% by weight, which was used.

A solution containing the above components (solid content of 50 g of epoxy resin, 13.5 g of polythiol, 2.0 g of curing accelerator, 50 g of phenoxy resin) is applied to a 80 μm-thick fluororesin film using a coating apparatus. Then 70
A film made of an epoxy resin composition having a thickness of 25 μm was formed on the fluororesin film by drying with hot air at 10 ° C. for 10 minutes. Next, the film made of the epoxy resin composition was peeled off from the fluororesin film. The film made of the epoxy resin composition peeled from the fluororesin film has sufficient flexibility at room temperature and has a
Even after being left for 40 hours, the properties of the film hardly changed, indicating good storage stability.

Example 2 A polythiol was prepared from 13.5 g of pentaerythrithiol using trimercaptomethylpropane (SH equivalent of 60.000 g).
7) A film was obtained in the same manner as in Example 1, except that the film was prepared as 16.4 g. This film had good properties equivalent to Example 1.

Comparative Example 1 A polythiol-ester resin (manufactured by Asahi Denka Kogyo KK, trade name: Adeka Hardener EH317, SH equivalent weight: 14) was prepared from 13.5 g of pentaerythrithiol.
0) A film was obtained in the same manner as in Example 1, except that the amount was changed to 37 g.

Comparative Example 2 The polythiol curing agent was pentaerythrithiol 13.5.
g, a hydroxyl group-containing polythiol-ether resin (Adeka Hardener E, manufactured by Asahi Denka Kogyo KK)
H310, SH equivalent 190) A film was obtained in the same manner as in Example 1 except that the amount was changed to 50 g.

Comparative Example 3 The polythiol curing agent was pentaerythrithiol 13.5.
g was changed to 28.9 g of 2,2 ′-(ethylenedithio) diethanethiol (SH equivalent: 107) to obtain a film in the same manner as in Example 1.

[Measurement of Adhesive Strength] Examples 1 and 2, Comparative Example 1
Using a film obtained by forming a film made of an epoxy resin composition having a thickness of 25 μm on a fluororesin film obtained in Steps 3 to 3, using a line width of 50 μm, a pitch of 100 μm, and a thickness of 1
A flexible circuit board (FPC) having 500 8 μm copper circuits was heated and pressed at 110 ° C. and 2 MPa for 20 seconds and connected over a width of 2 mm. At this time, a thickness of 25 μm was previously formed on one FPC and on a fluororesin film.
After attaching a film surface made of an epoxy resin composition having a thickness of 25 μm to a film formed of an epoxy resin composition of above, a temporary connection was made by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then fluorine The resin film was peeled off and connected to the other FPC to obtain a connected body. The adhesive strength of this connection body was measured by a 90-degree peeling method according to JIS-Z0237 and evaluated, and the results are shown in Table 1. The measuring device was Tensilon UTM-4 manufactured by Toyo Baldwin Co., Ltd.
(Peeling speed 50 mm / min, 25 ° C.).

[0031]

[Table 1]

The film made of the epoxy resin composition obtained in Examples 1 and 2 showed good short-time adhesion at 100 ° C., and the adhesion reached a sufficient strength. Comparative Examples 1 to 3 in which no was used had insufficient adhesive strength.

[0033]

According to the first aspect of the present invention, there is provided an epoxy resin composition which has a sufficient pot life, is rapidly cured at a relatively low heating temperature, and has a strong adhesive strength.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Lee Army 4-3-1, Higashicho, Hitachi, Ibaraki Pref. Hitachi Chemical Co., Ltd.

Claims (1)

[Claims] 1. An epoxy resin composition comprising (A) an epoxy resin and (B) a polythiol having at least three mercapto groups in one molecule and comprising only carbon, sulfur and hydrogen atoms.