JPS60248740A - Manufacture of laminated sheet - Google Patents

Abstract

PURPOSE:To obtain a laminated sheet having excellent electrical insulation, etc., by impregnating a substrate made of a blended nonwoven cloth of a cellulosic fiber and glass fiber having a specific water-content with the first hydrophilic thermosetting resin, and then with the second thermosetting resin, drying the product, and hot-pressing the obtained prepreg sheets. CONSTITUTION:A cellulosic pulp (e.g. craft pulp) is blended to glass fiber, and the mixture is formed to a sheet with a conventional paper-making machine and dried to obtain a blended nonwoven cloth of cellulosic fiber and glass fiber having a water-content of >=4wt%. The nonwoven cloth is used as the substrate, and is impregnated first with a hydrophilic thermosetting resin (e.g. precondensate of a phenolic resin), and then with the other thermosetting resin (e.g. epoxy resin). The impregnated product is dried to obtain a prepreg. The objective laminated sheet can be manufactued by stacking the prepreg sheets and hot-pressing the laminate. EFFECT:Excellent electrical insulation, moisture resistance, and punchability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing a laminate using a cellulose fiber-mixed glass nonwoven fabric as a base material.

BACKGROUND OF THE INVENTION Glass nonwoven fabrics mixed with cellulose fibers are available at a lower cost than nonwoven fabrics made of glass fibers alone, and have sufficiently high mechanical strength, so they are often used as base materials for laminates. A prepreg obtained by directly impregnating and drying this base material with a hydrophobic thermosetting resin, or by improving this method, impregnating the first hydrophilic thermosetting resin in advance. Then, a prepreg obtained by impregnating and drying a hydrophobic second thermosetting resin is heated and press-molded to produce a laminate.

Problems to be Solved by the Invention However, the above laminates all have moisture resistance, electrical insulation,
There is a drawback of poor punching workability, and the object of the present invention is to solve this problem.

Means for Solving the Problems In order to achieve the above object, the present invention uses a cellulose fiber-mixed glass nonwoven fabric with a moisture content of 4% by weight or more after papermaking and drying as a base material, and provides hydrophilic properties to the base material. The prepreg is characterized in that after being impregnated with a first thermosetting resin having properties, a prepreg obtained by impregnating and drying a second thermosetting resin is heated and press-molded.

Function The water content of commercially available glass nonwoven fabrics mixed with cellulose fibers is approximately 2% by weight, and by using fabrics with a water content of 4% by weight or more after papermaking and drying, it is possible to use a nonwoven fabric as a base material when impregnating with resin. better permeability. the result,
This improves the moisture resistance, electrical insulation, and punching workability of the laminate. When a base material with a water content of less than 4% by weight after papermaking and drying is used, the impregnated resin exists only around the cellulose fibers and does not sufficiently penetrate into the base material. Also,
The impregnation property of the resin depends on the moisture content of the base material after papermaking and drying, and the water content after papermaking and drying is 4% by weight.
Even if the base material with a lower water content is subsequently allowed to absorb moisture and impregnated with a resin by increasing the water content, the impregnating property will not improve.

Examples The cellulose fiber-mixed glass nonwoven fabric used in the present invention is
It is made by mixing cellulose pulp such as kraft, manila hemp, and mitsumata with glass fiber, and is made using a normal paper making machine and dried. The first thermosetting resin having hydrophilic properties used in the present invention is a water-soluble resin such as a phenol resin initial condensate or a jepoxy compound having a polyether bond. Further, the second thermosetting resin is any thermosetting resin used for laminates, such as epoxy resin, phenol resin, melamine resin, and polyester.

Next, the present invention will be explained in detail.

Example 1 A cellulose fiber-mixed glass nonwoven fabric (glass/kraft = 70/30 (parts by weight) (moisture content after papermaking and drying: 10% by weight) was used as a base material, and methylol and phenol resin were added in an amount of 10% by weight. The prepreg was further impregnated with epoxy resin so that the total resin amount was 60% by weight and dried to obtain a prepreg. The prepregs were stacked at a temperature of 17
A laminate with a thickness of 1.5 mm was obtained by heat-pressing molding at 0° C. and a pressure of 3 Q kg/cm 2 for 30 minutes.

The above methylolphenol resin is prepared by mixing 1 mole of phenol with 2 moles of formaldehyde (3796 formalin) and 17 liters of barium hydroxide, reacting at 800C for 3 hours, and then neutralizing with a 20% sulfuric acid solution. was removed and diluted with water to have a resin solid content of 15% by weight. In addition, the epoxy resin was 100 parts by weight of Epon 1045 (trade name, manufactured by Yuka Shell), 4 parts by weight of dicyandiamide,
It contains 0.5 parts by weight of benzyldimethylamine.

Comparative Example 1 Using the same base material as in Example 1, which had a water content of 2% by weight after papermaking and drying, was made to absorb moisture to bring the water content to 10% by weight. A 6 mm thick laminate was obtained.

Conventional Example 1 Table 1 shows the results of characteristic tests conducted on each of the above laminates according to JIS-C-6481.

The punching workability was expressed by a pitch interval of 2.5 mm and a crack occurrence rate between punch holes.

Effects of the Invention As is clear from Table 1, the laminates obtained in Table 1 according to the present invention have less hygroscopic deterioration of electrical resistance and lower water absorption than conventional ones, and therefore have excellent electrical insulation and moisture resistance. It is extremely excellent in terms of strength and punching workability. In this respect, the industrial value of the present invention is enormous.

patent applicant Shin-Kobe Electric Co., Ltd.

Claims (1)

[Claims] A glass nonwoven fabric mixed with cellulose fibers having a moisture content of 4% by weight or more after papermaking and drying is used as a base material, and after impregnating the base material with a first thermosetting resin having hydrophilic properties, a second thermosetting resin is applied. A method for manufacturing a laminate, characterized by heating and press-molding a prepreg obtained by impregnating and drying a resin.