JPH02120331A - Production of phenol resin laminate - Google Patents

Abstract

PURPOSE:To improve electrical characteristics, humidity resistance and punchability by drying a paper base material impregnated with a specified emulsion varnish, impregnating with an oil-modified phenol resin varnish, drying and molding under heat and pressure. CONSTITUTION:An emulsion varnish is obtd. by dispersing an oil-modified phenol resin, a methylol-phenol resin, a curing accelerator (e.g., benzylmethylamine) and a surface active agent in water and emulsifying the mixture. After a paper base material is impregnated with this emulsion varnish and dried, it is impregnated with an oil-modified phenol resin varnish and dried to obtain a prepreg. Then, these prepregs of a specified number are laminated and molded under heat and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing paper-based phenolic resin laminates for electrical insulation.

Conventional technology Phenolic resin laminates are widely used as insulating substrates for printed circuits, especially in the field of consumer electronics.Especially in recent years, as electronic components have become more densely packaged and highly functional, the electrical properties of laminates have improved. and requirements for machinability are becoming increasingly strong.

In order to meet the above market needs, conventionally, a varnish for undercoating was prepared by diluting methylolphenol resin in an organic solvent (methanol, acetone, doluol, etc.) at a concentration of about 10 to 30% by weight, and this was applied to paper. A two-step impregnation-drying method has been implemented in which the base material is impregnated and dried, and then a top coat varnish (oil-modified phenolic resin varnish or methylol phenolic resin varnish with a binder added) is impregnated and dried. (penetration of the resin into the base material) is low,
In order to improve the punching workability, methods such as increasing the amount of oil modification in the top coat varnish or adding a large amount of plasticizer have been adopted, but the interlayer adhesion of the laminate decreases, making it difficult to punch out dense small holes. is inferior.

Problems to be Solved by the Invention As mentioned above, in the conventional technology, there is a problem in that the level of interlayer adhesion, electrical properties, moisture resistance properties, etc. when forming dense small holes is low, especially with regard to punching workability. In order to improve the properties of these laminates, it is necessary to increase the permeability of the resin into the paper base material. As a method, it has been proposed to use a large amount of water in the varnish to swell the fibers of the paper base material during impregnation, making it easier for the resin to penetrate.
The aforementioned methylolphenol resin does not dissolve in water and separates, making impregnation impossible. To solve this problem, it is possible to use a varnish made of a resin emulsion.
Production efficiency decreases due to the drying capacity of the drying process.

From these viewpoints, the present invention aims to efficiently produce a paper-based phenolic resin laminate having excellent electrical properties, moisture resistance properties, and punching workability.

Means for Solving the Problems In order to achieve the above objects, the present invention provides the following (a) to
The method is characterized in that the prepreg obtained through the step (c) is molded under heat and pressure.

(a) A varnish is prepared in which an oil-modified phenol resin, a methylol phenol resin, and a hardening accelerator are emulsified with a surfactant and water as a dispersion medium.

(0) The emulsion varnish is impregnated into a paper base material and dried (undercoating step).

(c) Furthermore, it is impregnated with an oil-modified phenol resin varnish and dried (top coating step).

Function: In the present invention, since an emulsion varnish using water as a dispersion medium is used, the fibers of the paper base material can be swollen and the emulsified resin can be infiltrated therein. and,
The presence of the oil-modified phenolic resin in the undercoating process increases the affinity with the oil-modified phenolic resin in the topcoating process, contributing to the production of a laminate with excellent properties.

Further, in drying in the undercoating process, the presence of a curing accelerator promotes the curing reaction of the resin to the B stage, leading to increased efficiency. Furthermore, this B-stage curing reaction also promotes the conversion of mononuclear phenol and mononuclear methylolphenol into polynuclear compounds, which improves raw material yield by reducing volatile matter during the drying process. You can also aim for

Example An embodiment of the present invention will be described.

Example 1 Tung oil modified phenolic resin varnish (solid content 80 g) and methylol phenolic resin varnish (solid content 20 g) were mixed, and surfactant 1 (H, L, B, = 6) 3
g and surfactant 2 (11, L, B, = 16) 3 g
and 1 g of benzylmethylamine and 8 ounces of water as a curing accelerator.
00g was added and mechanically stirred with a stirrer to uniformly emulsify and disperse the phenolic resin emulsion (KRAFT), which was then impregnated and dried. %) and dried to produce a prepreg with a total resin content of 48% by weight. 8 of these prepregs were stacked, a copper foil with adhesive was layered on one side, and the pressure was 100kg/c4 and the temperature was 160℃.
A copper clad laminate having a thickness of 1.6 mm was manufactured by heating and pressing at °C for 90 minutes.

Comparative Example 1 Tung oil modified phenolic resin varnish (solid content 80 g) and methylol phenolic resin varnish (solid content 20 g) were mixed, and 3 g of surfactant 1 (11, L, B, = 6) was mixed.
3 g of surfactant 2 (11, L, B, = 16) and 800 g of water were added and mechanically stirred with a stirrer to prepare a uniformly emulsified and dispersed phenolic resin emulsion varnish (concentration 10% by weight). did.

This emulsion varnish was used for undercoating, and a copper-clad laminate was manufactured in the same manner as in Example 1.

Comparative Example 2 A methylolphenol resin varnish (concentration 15% by weight) was prepared by adding 500g of methanol to 100g of solid content of methylolphenol resin and stirring.

This varnish was used for undercoating, and a copper-clad laminate was manufactured in the same manner as in Example 1.

Table 1 shows the results of characteristic and performance tests on these copper-clad laminates. In addition, the raw material yield in the impregnation drying process,
A comparison of efficiency is shown in Table 2.

Table 1 Table 2 Effects of the Invention As described above, according to the present invention, an undercoat varnish is prepared by adding a surfactant, a curing accelerator, and water to an oil-modified phenol resin and methylol phenol resin combination system to form an emulsion. By using it, it is possible to improve the processing effect of the paper base material, and it is possible to greatly improve the impregnation property of the top coat varnish.

As a result, as shown in Table 1, the electrical properties, moisture resistance properties, and punching workability of the phenolic resin laminate were significantly improved compared to conventional products.

Furthermore, the efficiency (drying speed) and raw material yield in the impregnating and drying process can be improved.

Furthermore, the use of an emulsion varnish with an aqueous dispersion medium reduces the amount of organic solvent used, which greatly improves work safety.

Claims (1)

[Scope of Claims] A method for producing a phenolic resin laminate, in which a prepreg obtained through the following steps (a) to (c) is molded under heat and pressure. (a) Prepare a varnish made by emulsifying oil-modified phenol resin, methylol phenol resin, and hardening accelerator with a surfactant and using water as a dispersion medium, and (b) Impregnate a paper base material with the emulsion varnish and dry it. Step (c) Further, a step of impregnating with an oil-modified phenol resin varnish and drying is performed.