JPS62218464A - Varnish for laminated sheet - Google Patents

Abstract

PURPOSE:To obtain a varnish for laminated sheets, which gives copper-clad laminates having excellent peel strength without applying any adhesive to a copper sheet and reduces costs, by using a specified amount of tetrabromobisphenol A as part of a curing agent for epoxy resins. CONSTITUTION:This varnish for laminated sheets is obtd. by incorporating tetrabromobisphenol A in an amount corresponding to 30-80 equivalent % of the total amount of curing agent as a curing agent for epoxy resins.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a laminate varnish that improves the beer strength of copper-clad laminates. The present invention relates to a varnish for laminates that provides excellent beer strength even without the use of an adhesive.

(Prior art) Copper-clad laminates are generally produced by impregnating a paper cloth base material such as kraft paper or glass mat with a thermosetting resin varnish made by dissolving epoxy resin or the like in a solvent, and then drying it to remove the solvent. Create semi-hardened prepreg. The required number of prepreg sheets are then stacked one on top of the other, copper foil is placed on one or both sides of the prepreg, and the prepreg is integrally molded under heat and pressure.

(Problem to be solved by the invention) However, the adhesive strength between the copper foil and the prepreg varies depending on the thickness of the copper foil, and while a copper foil with a thickness of 35 μm can provide the necessary beer strength, a copper foil with a thickness of 18 μm Copper foil has the disadvantage that it does not provide the necessary adhesive strength and lacks beer strength. Therefore, in order to increase the adhesive strength and improve beer strength, adhesives are applied to copper foil, but the number of steps increases due to the use of adhesives, making copper-clad laminates more expensive. There was a drawback.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and it is possible to obtain a copper-clad laminate with excellent beer strength without using an adhesive for copper foil, and to use it for a laminate that contributes to cost reduction. The purpose is to provide varnishes.

[Structure of the invention] (Means and effects for solving the problem) In order to increase beer strength without using adhesive, the present inventor has
As a result of intensive research to improve the varnish that is impregnated into prepreg, we investigated the hardening agent in the varnish and incorporated tetrabromobisphenol△ into the hardening agent to improve the stability of the varnish. The inventors have completed the present invention by discovering that the moldability of the laminates can be maintained as is currently available, and that the beer strength of the copper-clad laminates produced is also excellent.

That is, the present invention is a laminate varnish characterized by containing 30 to 80 equivalent percent of the total curing agent of tetrabromobisphenol Δ as a curing agent for epoxy resin.

The epoxy resin used in the present invention is not particularly limited and includes commonly used epoxy resins, but glycidyl ether-based ones are used. Specific examples include Epicote 1001° Epicote 1004 (manufactured by Yuka Shell Co., Ltd., trade name), YDB-500, YDB-71.
5 (manufactured by Tobu Kasei Co., Ltd., trade name), etc., and these are 1
It is used as a species or a mixture of two or more species.

The blending ratio of tetrabromobisphenol A used as a curing agent for epoxy resin in the present invention is 30 to 8 of the total curing agent.
It is desirable that it is 0 equivalent %. If this proportion is 30 equivalent%, the desired beer strength cannot be obtained, and 8.
If it exceeds 0 equivalent %, the proportion of the three-dimensional structure of the cured varnish will decrease, resulting in poor strength when heated, which is not preferable. By using tetrabromo bisphenol 8 as a curing agent, the cured resin becomes tough, the adhesive strength between the prepreg and the copper foil increases, and the beer strength improves. In addition to tetrabromobisphenol A, other curing agents are used in combination, but in consideration of the stability of varnishes and prepregs, latent curing agents such as dicyandiamide, BF, 3-amine, and low molecular weight novolac types are used. Examples include phenol resins, which are used to make up for the curing agent amount of tetrabromobisphenol A.

The varnish for laminates of the present invention contains an epoxy resin, tetrabromobisphenol A, and other curing agents, but can also contain curing accelerators and other additives if necessary. A varnish for laminates can be easily prepared by blending the above ingredients and diluting with thinner to adjust the viscosity to an appropriate level.

The thus obtained varnish for laminates is impregnated into a paper fabric base material, dried and the solvent is removed to obtain a semi-cured prepreg. A copper-clad laminate can be produced by stacking a required number of prepregs, placing copper foil on one or both sides, and curing with a hot press at 150 to 170° C. for about 1 hour.

(Example) Next, the present invention will be explained by referring to an example. The present invention is not limited to the following examples.

Example 1 653 g of 75% methyl ethyl ketone solution of Ebicor 1-1001 (trade name, manufactured by Yuka Shell Co., Ltd., epoxy equivalent weight 490)
2 of a 10% dimethylformamide solution of tetrabromobisphenol A and dicyandiamide.
0 g, then diluted in a mixed solvent of methyl ethyl ketone and quidylole, and 2-ethyl-4 as an accelerator.
-Methylimidazole 0.3fi amount% (based on resin)
was added to obtain a varnish for laminates. This was applied to a glass cloth having a thickness of 0.18 and dried to produce a prepreg with a resin adhesion amount of 43% by weight. Layer 8 sheets of this prepreg, layer 18μm copper foil on both sides, and heat to 55℃.
After holding at an initial pressure of 15 ka/am at 2.70° C. and 30 kg/Cl 112 for 1 hour in a press heated to 100° C., the mixture was cooled to obtain a copper-clad laminate.

When the beer strength of the copper-clad laminate thus obtained was tested, it was 2.05 kmcm, and the effect of the present invention was recognized.

Example 2 Tetrabromobisphenol A 19
Shonol BRG-558 (manufactured by Showa Kobunshi Co., Ltd., trade name) is a novolak type phenolic resin with a low molecular weight of 0g.
21.2 (l), diluted with a mixed solvent of methyl ethyl ketone and quidylole, and 0.3% of 2-ethyl-4-methylimidazole (based on the resin) as an accelerator.
A varnish for laminates was prepared by adding . This varnish was applied to a 0.18 t thick kraft paper for paper epoxy and dried to produce a prepreg with a resin content of 43% by weight. Copper foil with a thickness of 18 μm was layered on one side of six sheets of prepreg, and the initial pressure was 30 ko/min using a press heated to 155°C.
After holding at 80 kg/cm2 at 70°C for 1 hour, it was cooled to obtain a copper-clad laminate. When the beer strength of the copper-clad laminate thus obtained was tested, it was found to be 2.1 ko/c.
m, and the effect of the present invention was confirmed.

Comparative Example A copper-clad laminate was obtained in the same manner as in Example 2 except that tetrabromobisphenol A was removed. When this copper-clad laminate was tested for beer strength, it was impossible to achieve a beer strength of 1.5 ko/cm or more.

[Effects of the Invention] The varnish for laminates of the present invention uses tetrabromobisphenol A as part of the curing agent in the varnish, so it can provide excellent beer strength without using an adhesive on the copper foil. By not using an adhesive, an increase in the number of steps and an increase in cost can be prevented, and therefore it is extremely useful industrially.

Claims (1)

[Claims] 1. A laminate varnish containing 30 to 80 equivalent percent of the total curing agent of tetrabromobisphenol A as a curing agent for epoxy resin.