JPS5838313B2 - Polyamide polyamide - Google Patents

Description

[Detailed Description of the Invention] It is widely known that in power equipment such as transformers and electric motors, the presence of pores inside insulators used under high electric field strength causes discharge deterioration and dielectric breakdown. It is being

An object of the present invention is to provide a method for manufacturing a molded article that does not have pores and does not suffer from corona deterioration even when used under high electric field strength.

The present invention is based on a method in which a prepreg is made by applying a resin to a base material, a required number of prepregs are laminated, and a molded article of a desired shape is obtained by pressure molding while heating.

In the present invention, an aromatic polyamide paper having excellent heat resistance, particularly one having good resin impregnation property, such as Nomex Type 411 or E54A (trade name), is used as the base material.

Aromatic polyamide paper has strong hygroscopicity, usually 5 to 8 wt%
contains water.

However, if moisture remains in the Prefreg base material,
It has been found that this adversely affects the flow characteristics of the B-stage resin during molding, causing foaming and causing voids.

When manufacturing prepreg, heat treatment is performed, but there are certain restrictions in terms of dry hardening degree and workability. For example, heat treatment at 120°C
Heating takes only about 10 minutes.

With this level of heating, it is difficult to sufficiently dehydrate the moisture adsorbed on the base material.

Therefore, in the method of the present invention, before producing the prepreg, the base material is sufficiently dried by heating it at a low temperature or for a long time, etc., and the epoxy compound resin is applied without re-absorbing moisture. To maintain good flow characteristics of B-stage resin during molding and prevent foaming.

The moisture content in the prepreg base material must be measured, for example, by a special gas analysis method using an improved elemental analyzer, and must be carefully sealed.

In order to make a laminated molded product without voids, the base material must be sufficiently dried, and at the same time, as an epoxy compound resin, it is easy to blend with the base material and has good flow characteristics when heated and cured, i.e., has a low flow viscosity. It is required to use something.

Epoxy compound resins that meet this requirement include, for example, a bisphenol type epoxy resin mixed with a novolac type or cycloaliphatic type epoxy resin at a certain ratio, and a mixture of aromatic amines and acid anhydrides. Examples include those to which agents and catalysts are added.

On the other hand, when dicyandiamide is used as a curing agent, curing takes an extremely long time, resulting in a lack of workability.

When an appropriate number of prepreg sheets are laminated and pressure molded while heating to produce a molded product of a desired shape, if a metal or molding pressure is suddenly applied, if air bubbles exist in the prepreg, they will not be able to escape and the molded product will be damaged. I realized that I was trapped inside.

Therefore, in the present invention, the prepreg laminate is first heated under a pressure sufficient to bring the prepregs into close contact with each other, that is, contact pressure is applied to melt the resin, and then the pressure is gradually increased, that is, in steps. Therefore, the molding process was performed while trying to eliminate air bubbles.

Next, the present invention will be described with reference to specific examples.

A prepreg was made by using Nomex type 411, which has good resin impregnation properties, as a base material for aromatic polyamide paper, thoroughly drying it, and applying an epoxy blended resin without reabsorbing moisture.

This resin is a bisphenol A type with an epoxy equivalent weight of about 500 (trade name Epicor 1001 (or trade name Araldite) 6071), and a novolac type resin with an epoxy equivalent of about 200 (trade name Epicor) 154 (or trade name Araldite ECN 1235). ) in equal amounts,
A theoretical amount of hexahydrophthalic anhydride was used as a curing agent, and 0.1 to 0.0% of a reaction accelerator was used to adjust the curing conditions.
5 wt% was added.

The required number of sheets of prepreg were laminated and set in a press set at 170°C.
Apply a contact pressure of about 100 kg/cvt, leave it for about 10 minutes to completely melt the resin, then apply a pressure of about 10 kg/cvt and heat for 20 minutes, and increase the pressure in stages to finally reach 30 kg/cfL. Increase and heat at this final pressure for 2 hours.

The precepts produced in this way cost 3KV/rrat.
corona exposure at an electric field strength of less than lpc,
It was confirmed that no upper pores actually existed.

The dielectric breakdown voltage (short time) also showed an extremely excellent value of 40 KV/mm or more.

Claims (1)

[Claims] 1. Make a prepreg by applying an epoxy compound resin with good heat resistance and flow characteristics to dried aromatic polyamide paper with good resin impregnation properties, laminate the required number of sheets, and heat with contact pressure applied. A method for manufacturing an aromatic polyamide paper laminate molded article, which comprises melting the resin and then heating it while gradually increasing the pressure to form a certain shape.