JPH0469660B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing an epoxy resin laminate with excellent mechanical and electrical properties. BACKGROUND OF THE INVENTION Epoxy resin laminates are widely used as circuit boards in the fields of industrial and consumer electronic devices. With the recent increase in the density and functionality of electronic components, demands on the electrical and mechanical properties of laminates are becoming increasingly strict. Glass nonwoven fabric is often used as the base material for epoxy resin laminates, and some or all of it is laminated with prepreg, which is impregnated with epoxy resin varnish and dried.In order to meet the above requirements, Prior to impregnating the glass nonwoven fabric with an epoxy resin varnish, it is pretreated with a varnish prepared by dissolving a phenolic resin initial condensate in a mixed solvent of methanol and acetone. Furthermore, by improving this,
The affinity between the glass nonwoven fabric base material and the resin has been improved by changing the mixing ratio of the resin and solvent in the pretreatment varnish or by adding a surface treatment agent such as a silane coupling agent. Problems to be Solved by the Invention However, the conventional technique of pretreating a glass nonwoven fabric substrate using a mixed system of a phenolic resin initial condensate and a solvent as a varnish has the following problems. (1) If the prepreg that has been further impregnated with epoxy resin varnish and dried is laminated and molded while the solvent from the pretreatment stage remains, the curing due to the solvable decomposition reaction of the epoxy resin will be accelerated.
There is a risk that the electrical properties and mechanical properties of the obtained laminate may deteriorate. (2) During heat drying in the pretreatment process, if the boiling point of the solvent is low and rapid solvent evaporation occurs in the drying oven, the phenolic resin initial condensate will migrate to the surface layer of the base material, and the epoxy resin There is a risk that the impregnation may be insufficient. (3) It is possible to increase the amount of resin deposited in the pretreatment process to improve the affinity with the epoxy resin that is subsequently impregnated, but due to constraints on the total amount of resin, the amount of epoxy resin deposited may be As a result, the adhesive strength between the base material layers of the obtained laminate decreases, and the targeted improvement in properties cannot be expected. (4) On the other hand, when attempting to improve properties by reducing the amount of resin deposited in the pretreatment process, a large amount of solvent is required, which increases costs and poses safety problems in terms of disposing of volatilized solvent. occurs. An object of the present invention is to solve the above-mentioned problems caused by pre-treating a glass nonwoven fabric base material, and to provide an epoxy resin laminate with excellent mechanical properties and electrical properties. Means for Solving the Problems In order to achieve the above object, the present invention uses a phenolic resin initial condensate as a pretreatment of the glass nonwoven fabric in the process of impregnating and drying the glass nonwoven fabric with an epoxy resin varnish to produce a prepreg. The feature is that a hydrophilic emulsifier (HLB10-12) is added to the mixed system of water and water to impregnate the emulsion varnish. Part or all of this prepreg is laminated and molded. Function The present invention improves the wettability of the surface of glass nonwoven fabric (epoxy resin or kraft pulp is used as a binder for glass fibers) due to the presence of an emulsifier in the pretreatment process, and improves the wettability of the surface of glass nonwoven fabric (epoxy resin or kraft pulp is used as a binder for glass fibers). The resin emulsion particles can penetrate between the fibers of the glass nonwoven fabric, increasing the pretreatment effect of the glass nonwoven fabric. In addition, since emulsion varnish uses water as a dispersion medium, the resin content does not migrate to the surface of the glass nonwoven fabric during the drying process, unlike in the case of pretreatment with conventional solvent varnish. Uniform impregnation is achieved in both cases. Examples Next, examples of the present invention will be described. Example 1 Phenol resin initial condensate (resin content 50wt%)
In a mixed system of 100 parts by weight and 300 parts by weight of water.
HLB12 emulsifier (product name Noniball, Sanyo Chemical
Co., Ltd., and stirred with a high-speed stirrer to form an emulsion to obtain an emulsion varnish for pretreatment. The particle size of the emulsion was 3 to 7 microns. The varnish was applied to a glass nonwoven fabric with a basis weight of 135 g/ ^m2 ,
Pretreatment was performed by impregnating and drying the resin to a resin content of 12 wt%. Next, a bisphenol A type epoxy resin varnish containing a curing agent (amine type) was impregnated and dried to obtain a prepreg with a total resin content of 57 wt%. 8 plies of this prepreg were stacked at 160℃, 60℃
A laminate with a thickness of 1.6 mm was obtained by heating and pressing at Kg/cm ² for 60 minutes. Example 2 The same epoxy resin varnish as in Example 1 was applied to both sides of the 6-ply prepreg used in Example 1.
One glass cloth prereg with a resin content of 43 wt% obtained by impregnating and drying a 205 g/m ² glass cloth was arranged, and heated and pressurized in the same manner as in Example 1 to a thickness of 1.6 mm.
A laminate was obtained. Comparative Example 1 Phenol resin initial condensate similar to Example 1
A pretreatment varnish was prepared by mixing and stirring 100 parts by weight with 300 parts by weight of methanol, and a prepreg with a total resin content of 57 wt% was obtained in the same manner as in Example 1. The 8 plies of prepreg were heated and pressed in the same manner as in Example 1, and the thickness
A 1.6 mm laminate was obtained. Comparative Example 2 The 6 plies of prepreg used in Comparative Example 1 were placed on both sides, and the glass cloth prepreg used in Example 2 was placed on each side, and heated and pressed in the same manner as in Example 1 to form a laminate with a thickness of 1.6 mm. Obtained. Each of the laminates obtained above was tested for insulation resistance as electrical properties, punching workability as mechanical properties, and water absorption.
Shown in the table.

[Table] Effects of the invention As described above, according to the present invention, an emulsifier is added to a mixed system of a phenolic resin initial condensate and water to form an emulsion as a pretreatment varnish. The glass nonwoven fabric base material can be uniformly and sufficiently impregnated with the treatment resin, and the affinity between the base material and the subsequently impregnated epoxy resin is improved through the pretreatment resin, and the resulting laminate can be treated with moisture absorption. This has the effect of improving later electrical properties and punching workability at low temperatures. In addition, since water is used as the dispersion medium for the pretreatment varnish, it is advantageous in terms of cost, and the generation of solvent gas during the impregnation and drying process is suppressed, which is effective in terms of fire safety and human hygiene.

Claims (1)

[Claims] 1. In the process of impregnating and drying a glass nonwoven fabric base material with epoxy resin varnish to produce prepreg,
A prepreg obtained by pre-treating the glass nonwoven fabric substrate with a varnish made by adding a hydrophilic emulsifier (HLB10 to 12) to a mixed system of a phenolic resin initial condensate and water to form an emulsion, and then impregnating and drying with an epoxy resin varnish. A method for manufacturing a laminate, characterized in that part or all of the above are laminated and molded.