JPH06220409A - Thermosetting adhesive sheet - Google Patents

Abstract

PURPOSE:To obtain the subject sheet which is excellent in workability because of, e.g. rapid curability and good flowability, gives bonding performance excellent in bonding strength, and is useful for bonding metal parts and polymeric materials in the fields of machinery and electrical and electronic equipment. CONSTITUTION:This adhesive sheet is made by laminating an epoxy resin composition consisting of an epoxy resin and a curing agent in or on a support layer. The composition contains an epoxy resin of the formula (wherein X is an oxygen or sulfur atom; G is glycidyl; R1 to R8 are each H, halogen or a 1-6C hydrocarbon group; and (n) is an integer of 0 or greater).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to metal parts and polymers in the mechanical, electrical and electronic fields, which provide excellent adhesive workability such as fast curing and fluidity and excellent adhesive strength. The present invention relates to a thermosetting adhesive sheet useful for adhering materials.

[0002]

2. Description of the Related Art In recent years, in the mechanical, electrical and electronic fields,
Epoxy resin type thermosetting adhesives are often used for assembling metal parts and polymer materials. Above all, the sheet-like adhesive is used more and more because of its easy handling.

As the epoxy resin for such applications, solid bisphenol A type epoxy resins and novolac type epoxy resins have been used in many cases, but conventional epoxy resin compositions have relatively high viscosity. Therefore, there is a problem that the resin is not completely filled in the minute gaps of the base material. To overcome this problem, a thermosetting adhesive sheet containing a crystalline biphenyl epoxy resin has been proposed (JP-A-62-62).
-95373 publication).

However, due to the refinement of the field of use, there is a strong demand for an adhesive sheet using an epoxy resin composition having a lower viscosity and higher curability in order to improve productivity.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide excellent adhesive workability such as fast curing property and fluidity, and also to provide adhesive performance having excellent adhesive strength, in mechanical, electrical and electronic fields. It is to provide a thermosetting adhesive sheet useful for adhering metal parts and polymer materials.

[0006]

That is, the present invention provides a thermosetting adhesive sheet in which an epoxy resin composition comprising an epoxy resin and a curing agent is laminated in or on a support layer. The following general formula (1) is used as the epoxy resin component in the product.

[Chemical 2] It is a thermosetting adhesive sheet characterized by containing the epoxy resin represented by.

The epoxy resin used in the present invention is a diphenyl ether type or diphenyl thioether type epoxy resin in which X in the above general formula (1) is an oxygen atom or a sulfur atom. In addition, the above general formula (1)
In, R _{1 to} R ₈ are a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 6 carbon atoms. As the hydrocarbon group, methyl group, ethyl group, isopropyl group, tert-
A butyl group, a tert-amyl group, a phenyl group and the like are exemplified. Further, in the above general formula (1), n represents an integer of 0 or more, but in order to maintain the low viscosity, it is preferable to contain 50% by weight or more of an epoxidized compound having n of 0.

Since these epoxy resins are crystalline, they have a sharp melting point, exhibit extremely low viscosity at the same time they are dissolved, and have a curing performance superior to that of conventional epoxy resins. As the melting point of epoxy resin,
Those in the range of 40 to 130 ° C. are preferably used.

The epoxy resin can be produced by reacting a dihydroxydiphenyl ether compound or a diphenylthioether compound with epichlorohydrin.
For example, a dihydroxydiphenyl ether or diphenyl thioether compound is dissolved in an excess of epichlorohydrin and then dissolved in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide at 50 to 150 ° C., preferably 60 to 120 ° C. Examples include a method of reacting for 10 hours. In this case, the amount of epichlorohydrin used is 0.8 to 1 mol of the hydroxyl group in the dihydroxy compound.
The amount is 2 mol, preferably 0.9 to 1.2 mol.
After completion of the reaction, excess epichlorohydrin is distilled off, the residue is dissolved in a solvent such as toluene and methyl isobutyl ketone, filtered, washed with water to remove inorganic substances, and then the solvent is distilled off to obtain the desired epoxy resin. Can be obtained.

As the curing agent used in the present invention, those generally known as curing agents for epoxy resins can be used. For example, there are dicyanamide, amide resins, amines, acid anhydrides, phenolic compounds and the like.

Examples of the phenolic compound include divalent phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-bisphenol, 2,2'-biphenol, hydroquinone, resorcin, and naphthalenediol. ,
Or tris- (4-hydroxyphenyl) methane,
Trivalent or more phenols represented by 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, phenol novolac, o-cresol novolac, naphthol novolac, polyvinylphenol, and the like, further phenols, naphthols or Polyhydric phenol synthesized with a condensing agent such as formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, p-xylylene glycol of divalent phenols such as bisphenol A, bisphenol F, bisphenol S, hydroquinone, resorcin, naphthalenediol. And the like. Examples of acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic anhydride, nadic anhydride, and trihydric anhydride. Acid anhydrides such as meritic acid can be exemplified. As amines, 4,4′-diaminodiphenylmethane, 4,
4'-diaminodiphenylpropane, 4,4'-diaminodiphenylsulfone, m-phenylenediamine, p-
There are aromatic amines such as xylylenediamine and aliphatic amines such as ethylenediamine, hexamethylenediamine, diethylenetriamine and triethylenetetramine. These curing agents can be used alone or in combination of two or more.

In addition to the epoxy resin represented by the general formula (1) used as an essential component of the present invention, the resin composition of the present invention is a usual one having two or more epoxy groups in the molecule. You may use together an epoxy resin. For example, divalent phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone and resorcin, or tris- (4-
From trivalent or higher phenols such as hydroxyphenyl) methane, 1,1,2,2-tetrakis (4-hydroxyphenyl) methane, phenol novolac, o-cresol novolac, or halogenated bisphenols such as tetrabromobisphenol A There are derived glycidyl ether compounds and the like. These epoxy resins can be used alone or in combination of two or more, and the compounding amount of the epoxy resin represented by the general formula (1) is preferably 50% by weight or more in the whole epoxy resin. .

A conventionally known curing accelerator can be used in the resin composition of the present invention, if necessary. Examples include amines, imidazoles, organic phosphines, Lewis acids and the like. Epoxy resin 100
It is in the range of 0.2 to 5 parts by weight with respect to parts by weight.

Further, a rubber component such as a butadiene type, an acrylic type or a silicon type may be added to the resin composition of the present invention, if necessary.

Further, a filler can be used if necessary. Examples of the filler include spherical or crushed fused silica, crystalline silica powder, alumina powder, glass powder and the like, and inorganic and organic fibers such as glass fiber, carbon fiber and aramid fiber. Further, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a colorant such as carbon black, a flame retardant such as antimony trioxide, and the like can be used.

The epoxy resin composition used in the present invention is laminated on the support film after mixing the above-mentioned composition by a method such as crushing, melting, or solvent dissolution. The laminating method can be carried out by spraying or coating the epoxy resin composition in the form of powder or varnish on a support. The epoxy resin composition can be laminated on one side or both sides of the support. Alternatively, when the support is woven, nonwoven or porous, the epoxy resin composition can be used by impregnating the support layer.

The support used in the present invention is in the form of a film, such as paper, polyester, polyamide,
Organic film such as polyimide or woven or non-woven fabric of these organic fibers, further aluminum, copper,
A metallic film such as stainless steel is exemplified.

The thermosetting adhesive sheet of the present invention is arranged in the form of a base material to be adhered or between the base materials, and is adhered by a method such as hot pressing or hot roll pressure bonding.

The base material to be bonded is a metal material such as iron, aluminum, copper, stainless steel, titanium or silicon,
Examples include inorganic materials such as glass, and organic materials such as paper, wood, polystyrenes, polyamides, and polyimides.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following examples. Reference Example 1 (Synthesis Example of Epoxy Resin) 101 g of 4,4′-dihydroxydiphenyl ether was dissolved in 462.5 g of epichlorohydrin, 0.3 g of benzyltriethylammonium chloride was further added, and 48 at 70 ° C. under reduced pressure (about 150 mmHg). % Sodium hydroxide aqueous solution 83.3 g was added dropwise over 3 hours. During this period, water produced was removed from the system by azeotropic distillation with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropping was completed, the reaction was continued for another hour.
Then, the salt produced by filtration was removed, and the product was further washed with water and then the epichlorohydrin was distilled off to obtain 146.2 g of a pale yellow crystalline epoxy resin. Epoxy equivalent was 169 and melting point was 86 ° C. The melt viscosity at 150 ° C. was 0.2 poise.

Reference Example 2 (Synthesis Example of Epoxy Resin) 4,4′-Dihydroxydiphenylthioether 120
g, epichlorohydrin 960 g, and 48% aqueous sodium hydroxide solution 91.5 g were reacted in the same manner as in Reference Example 1 to obtain 178 g of a pale yellow crystalline epoxy resin. Epoxy equivalent was 175 and melting point was 52 ° C. 15
The melt viscosity at 0 ° C. was 0.2 poise or less.

Reference Example 3 (Synthesis Example of Epoxy Resin) 2,2'-Dimethyl-5,5'-di-tert-butyl-4,4'-dihydroxydiphenylthioether 12
The reaction was performed in the same manner as in Reference Example 1 using 0 g, epichlorohydrin 720 g, and 48% aqueous sodium hydroxide solution 55.7 g to obtain 149 g of a white crystalline epoxy resin. Epoxy equivalent was 239 and melting point was 121 ° C. 1
The melt viscosity at 50 ° C. was 0.2 poise or less.

Examples 1 to 4 and Comparative Example 1 Each component was dry-mixed according to the formulation shown in Table 1, finely pulverized, and sprinkled on a polyester nonwoven fabric at a rate of 200 g / m ² , and the same as above. The polyester non-woven fabric of was laminated and compressed by a press heated to 40 ° C. to obtain a thermosetting adhesive sheet. The thermosetting adhesive sheet thus obtained was used to measure gel time at 150 ° C., filling property, and adhesive strength. Fillability is such that a 10-sided thermosetting adhesive sheet is sandwiched in the center between two 50 mm-square steel plates heated to 150 ° C.
A load of 500 g was applied, and evaluation was made by the ratio of the resin coated area to the total area of the steel sheet. The adhesive strength is 15 mm in width and 10 m in length between two steel plates having a width of 15 mm and a length of 100 mm.
The thermosetting adhesive sheet of m was sandwiched, and after curing at 180 ° C. for 30 minutes, the shear adhesive strength was measured at 25 ° C.

[0024]

[Table 1] ^{* 1} Bisphenol A type solid epoxy resin (softening point 82
℃) ^{* 2} Phenol novolac (softening point 85 ℃) ^{* 3} 2-Methylimidazole

[0025]

INDUSTRIAL APPLICABILITY The thermosetting adhesive sheet of the present invention has excellent curability and filling properties, is useful for substrates such as metal, paper and plastic, and exhibits excellent adhesive performance.

Claims (2)

[Claims] 1. A thermosetting adhesive sheet in which an epoxy resin composition comprising an epoxy resin and a curing agent is laminated in or on a support layer, and the following general formula is used as the epoxy resin component in the epoxy resin composition. Formula (1) A thermosetting adhesive sheet comprising an epoxy resin represented by: 2. The thermosetting adhesive sheet according to claim 1, wherein a diglycidyl ether of 4,4′-dihydroxydiphenyl ether is used as the epoxy resin.