JPH1088094A - Fluororubber-base adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluororubber-base adhesive excellent in resistances to heat and moisture by compounding four specific ingredients. SOLUTION: A fluororubber-base adhesive in the form of a soln. in a low- boiling ketone solvent is prepd. by compounding 100 pts.wt. fluororubber (A) comprising a vinylidene fluoride-hexafluoropropene copolymer having 0.1-30% unsatd. bonds introduced into the molecule by the defluorination caused by the treatment with an alkaline substance (e.g. sodium hydroxide or potassium hydroxide) at 40-60 deg.C in a ketone solvent (e.g. acetone or methyl ethyl ketone) with 0-30 pts.wt. glycidyltype epoxy resin (B)(e.g. an epichlorohydrin-bisphenol A resin, an arom. glycidyl ether resin, or an aom. glycidylamine resin), 1-30 pts.wt. diamine compd. curative (C)(e.g. diaminodiphenyl sulfone or diaminodiphenylmethane), and 1-20 pts.wt. alicyclic bismaleimide compd. (D)(e.g. one represented by the formula). The adhesive is used e.g. for bonding a cover film of a flexible printed circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fluororubber adhesive. More specifically, the present invention relates to a fluororubber-based adhesive effectively used for bonding a cover film to a flexible printed wiring board.

[0002]

2. Description of the Related Art Vinylidene fluoride (VdF) -hexafluoropropene (HFP) copolymer rubber, vinylidene fluoride-hexafluoropropene-tetrafluoroethylene are used as adhesives for bonding a cover film to a flexible printed wiring board. Compounding glycidylamine type epoxy resin and diamine as a curing agent of the same amount to the unsaturated bond to fluororubber having unsaturated bond introduced into the molecule by alkali treatment of terpolymer rubber etc. Fluororubber-based adhesives are known. This adhesive shows good adhesiveness at room temperature in a heat resistance life test and a moisture resistance life test described later, but has a remarkable decrease in adhesive strength when heated.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluororubber adhesive comprising a glycidyl-type epoxy resin and a diamine compound curing agent mixed with a fluororubber having an unsaturated bond introduced into the molecule by alkali treatment. It is an object of the present invention to provide a material having excellent heat and moisture resistance.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This can be achieved by further blending an alicyclic bismaleimide compound with the fluororubber adhesive.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a fluororubber, a vinylidene fluoride-hexafluoropropene copolymer is generally used. The copolymerization ratio of vinylidene fluoride to hexafluoropropene is about 3 to 10, preferably about 3.5.
The weight ratio is in the range of ~ 5. In the copolymer, fluorinated olefins such as tetrafluoroethylene, ethylene, propylene, alkyl vinyl ether, hexafluoroisobutene, and vinyl acetate, olefins, vinyl compounds, and the like may be further copolymerized.

[0006] These vinylidene fluoride-hexafluoropropene copolymers are prepared in the presence of a ketone solvent such as acetone or methyl ethyl ketone in the presence of potassium hydroxide, sodium hydroxide, cesium hydroxide, calcium hydroxide, calcium carbonate, By treating with an alkaline substance such as triethylamine at a temperature from room temperature to about 70 ° C., preferably about 40 to 60 ° C., the compound is easily dehydrofluorinated to form an unsaturated bond in the molecule. Preferably, the amount of unsaturated bond formed is in the range of about 0.1-30%, preferably about 0.5-5%. In practice, commercially available products can be used as they are.

As the glycidyl-type epoxy resin and the diamine compound curing agent, the same ones as in the prior art are used.
As the glycidyl-type epoxy resin, epichlorohydrin-bisphenol A resin is generally used. In addition, an aromatic glycidyl ether resin, an aromatic glycidylamine resin, and a reaction product of an alicyclic carboxylic acid and epichlorohydrin. Dehydrochloride of the product is used. As the amine compound curing agent, for example, diaminodiphenylsulfone, diaminodiphenylmethane, m-phenylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine and the like are used. For each of these components, the glycidyl type epoxy resin is about 0 to 30 parts by weight, preferably about 5 to 15 parts by weight, and the amine compound curing agent is about 1 to 30 parts by weight per 100 parts by weight of the fluororubber. ,
Preferably, it is used in a ratio of about 5 to 15 parts by weight. Thus, even if the glycidyl type epoxy resin is not used,
The object of the present invention is achieved.

Further, as the alicyclic bismaleimide compound, a compound represented by the formula A bismaleimide compound represented by

The bismaleimide compound is 1,3-bis
It can be easily produced by reacting (aminomethyl) cyclohexane with maleic anhydride. In this reaction, maleic anhydride is generally used in a molar amount twice as large as that of 1,3-bis (aminomethyl) cyclohexane, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone or non-protons such as dimethylformamide and dimethylacetamide are used. The first-stage reaction, which is carried out at a reaction temperature of about 0 to 15 ° C. using an apolar solvent or the like as a reaction solvent, is first performed to form a bismaleamic acid represented by the following formula as an intermediate.

In the reaction of the second step, a basic catalyst such as triethylamine is generally added to the reaction mixture at about 0.01 to 0.1 with respect to the bismaleamic acid without particularly separating the formed bismaleamic acid. In addition, a dehydrating agent such as acetic anhydride was added in a molar ratio of about 1 to bismaleamic acid.
At a reaction temperature of about 15-50 ° C.
The reaction is carried out for about 3 hours to produce a bismaleimide compound which is a dehydration and cyclization reaction product.

The obtained bismaleimide compound is soluble in acetone, methyl ethyl ketone, tetrahydrofuran, chloroform, dimethylformamide and the like, and such a bismaleimide compound is about 1 to 20 parts by weight, preferably about 1 to 20 parts by weight, per 100 parts by weight of the fluororubber. It is used in a ratio of about 5 to 10 parts by weight. If the blending ratio is lower than this, the intended effect of the present invention cannot be obtained, while if it is used in a higher ratio, the curing time becomes longer, so that bismaleimide absorbs moisture and the adhesive is formed. It causes deterioration.

The adhesive containing the above components as essential components is
It is prepared and used as a low boiling organic solvent solution such as methyl ethyl ketone and acetone. When such an adhesive solution is used for bonding a cover film of a flexible printed wiring board, it is first applied onto a polyimide cover film and dried at, for example, 80 ° C. for 5 minutes. In this state, the bismaleimide performs an addition reaction with the diamine which has become the terminal of the epoxy-diamine copolymer, and consumes the amine bond. A copper foil on a base film is bonded to the coated surface in such a state by thermocompression bonding, and then cured by heating in an oven to obtain a flexible printed wiring board.

[0013]

According to the present invention, a bismaleimide compound is further compounded into a fluororubber adhesive obtained by mixing a (glycidyl-type epoxy resin) and a diamine compound curing agent with a fluororubber having an unsaturated bond in the molecule, thereby obtaining heat and moisture resistance. Excellent adhesive can be obtained. The fluororubber-based adhesive having such characteristics is effectively used for bonding a cover film of a flexible printed wiring board.

[0014]

Next, the present invention will be described by way of examples.

Reference Example 71 g of 1,3-bis (aminomethyl) cyclohexane was placed in a separable flask equipped with a stirrer, a thermometer and a dropping funnel.
(0.5 mol) and 284 g of methyl isobutyl ketone were charged and dissolved, and then 392 g of methyl isobutyl ketone was dissolved therein.
Then, a solution of 98 g (1 mol) of maleic anhydride dissolved therein was added dropwise at room temperature, and the mixture was further stirred for 1 hour. Continued
Triethylamine 5 g (0.05 mol) and acetic anhydride 51 g (0.5
Mol) was added and stirred for a further 3 hours. After completion of the reaction, the reaction mixture was poured into water, and 142 g (90% yield) of precipitated crystals were recovered as a target. Melting point: 142-144 ° C ¹ H-NMR: 6.8 ppm (double bond of bismaleimide) Infrared absorption spectrum (KBr): 1710 cm- ¹ (imide bond) 1760 cm- ¹ (imide bond)

Example 1 Unsaturated bond-introduced VdF-HFP copolymer rubber 100 parts by weight (FX-1061 manufactured by Nippon Mektron Co., Ltd.) Glycidyl-type epoxy resin 5〃 (oil coat shell epoxy product Epicoat 604) diaminodiphenyl sulfone 5〃 Alicyclic bismaleimide 5 メ チ ル methyl ethyl ketone 400 フ ッ 素 Fluororubber-based adhesive solution prepared from each of the above components is uniformly applied on a 25 μm-thick polyimide film at a thickness of 25 μm, and is applied at 80 ° C. for 5 minutes. The solvent is removed by heating and the adhesive is semi-cured. The adhesive sheet thus obtained was pressure-bonded to a copper foil at 180 ° C., and heat-cured at 180 ° C. for 12 hours.

Example 2 In Example 1, the amount of the alicyclic bismaleimide compound was changed to 20 parts by weight.

Example 3 In Example 1, no glycidyl type epoxy resin was used.

Comparative Example In Example 1, an alicyclic bismaleimide compound was not used.

The flexible copper foil adhesive sheet obtained in each of the above Examples and Comparative Examples was subjected to a heat resistance life test at 150 ° C. for 1000 hours and a moisture resistance life test at 85 ° C., 85% RH for 1000 hours. The adhesive strength at time (adhesive strength at room temperature after the test for 1000 hours) and the adhesive strength at heat (adhesive strength at 150 ° C. after the test for 1000 hours) were measured. The results obtained are shown in the following table.

Table 1 Adhesive strength at room temperature (kg / cm) Adhesive strength at heat (kg / cm) [Heat resistance life test] Example 1 1.6 0.85 〃 2 1.5 0.72 ３ 3 1.7 0.82 Comparative example 1.5 0.33 [Moisture resistance life test] Example 1 1.34 0.80 〃 2 0.85 0.80 ３ 3 1.50 0.82 Comparative example 1.55 0.23

Claims (3)

[Claims] 1. A fluororubber adhesive obtained by blending a glycidyl-type epoxy resin, a diamine compound curing agent and an alicyclic bismaleimide compound with a fluororubber having an unsaturated bond introduced into a molecule by alkali treatment. . 2. A fluororubber adhesive obtained by blending a diamine compound curing agent and an alicyclic bismaleimide compound with a fluororubber having an unsaturated bond introduced into the molecule by alkali treatment. 3. The fluororubber adhesive according to claim 1, which is used for bonding a cover film to a flexible printed wiring board.