JPH0355499B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing a flame-retardant phenolic resin laminate that requires high room-temperature punching workability, flame retardancy, heat resistance, and electrical properties. Recently, as the use of flame-retardant phenolic resin laminates as electric insulating substrates in consumer electronics has been increasing, the demand for high quality and low cost has become higher and higher. In order to obtain flame-retardant phenolic resin laminates with advanced electrical properties, the process of impregnating the base material with thermosetting resin is repeated twice: undercoating and topcoating, during the prepreg production stage for lamination molding. There is. Conventionally, a prepreg is produced by impregnating and drying a base material with an undercoat resin that is a mixture of a phenolic resin initial condensate and a melamine resin, and then impregnating and drying an oil-modified phenolic resin varnish containing a flame retardant and a flame retardant resin as a top coat resin. was. Problems to be solved by the invention Conventional methods ensure flame retardancy (UL-94V-
O), melamine resin is contained in the undercoat resin. On the other hand, the top coat resin contains large amounts of flame retardant resins such as brominated epoxy resins and flame retardants such as bromine compounds such as tetrabromobisphenol A (TBA) and triphenyl phosphate (TPP), and phosphorus compounds. Therefore, the resulting laminate has poor interlayer adhesion, poor punchability at room temperature and heat resistance, and is more expensive. Therefore, an object of the present invention is to provide an inexpensive flame-retardant phenolic resin laminate that has good room-temperature punchability and heat resistance. Means for Solving the Problems In order to achieve the above object, the present invention provides a mixture of a phenolic resin initial condensate and a melamine resin with 3 to 50% by weight of antimony pentoxide (Sb ₂ O ₅ in terms of solid content). A prepreg is produced through a first step of impregnating and drying an undercoat resin containing a sol into a base material, a second step of impregnating and drying an oil-modified phenol resin containing a flame retardant resin into the base material that has undergone the first step, This is characterized by lamination molding. Effects By having the above-mentioned characteristics, the present invention provides a flame-retardant phenolic resin laminate that requires high room-temperature punching workability, flame retardancy, heat resistance, and electrical properties. That is, from the viewpoint of improving flame retardancy, the step of treating the base material with the undercoat resin is very important and effective. Therefore, as a result of intensive studies using antimony pentoxide (Sb ₂ O ₅ ) sol in the undercoat resin, it became possible to reduce the amount of flame retardant in the topcoat resin, and the above objective was achieved. However, from Sb ₂ O ₅ sol to 3% by weight in the undercoat resin.
When the length was less than 100%, no effect of reducing the flame retardant in the top coat resin was observed. Furthermore, if the Sb ₂ O ₅ sol exceeds 50% by weight in the undercoat resin, the laminate becomes opaque, which poses a quality problem. The preferred amount is 15-30
Weight%. Examples Next, examples of the present invention will be described together with comparative examples and conventional examples. After impregnating and drying 11 mils kraft paper with the undercoat resin in the proportions (wt%) shown in Table 1 to a resin content of 10 to 15% by weight, further impregnating and drying the topcoat resin resulted in a resin content of 48%. ~51 wt% prepreg was produced. A predetermined number of sheets of this prepreg and 35 μ thick copper foil are laminated together on one surface of the prepreg, and molded under heat and pressure at 160℃ and 100Kg/cm ² .
A copper-clad laminate with a thickness of 1.6 mm was obtained.

[Table] In Table 1, the flame-retardant resin is a mixture of brominated epoxy resin and triphenyl phosphate. Table 2 shows the characteristics test results of the copper-clad laminates obtained in the above Examples, Comparative Examples, and Conventional Examples.

【table】

[Table] Effects of the Invention As described above, according to the present invention, as can be seen from Tables 1 and 2, the amount of flame retardant resin used together with the flame retardant in the top coat resin can be reduced while maintaining flame retardancy. Since it became possible to increase the amount of oil-modified phenolic resin, heat resistance and punching workability were improved. In addition, by using Sb ₂ O ₅ sol in the undercoat resin, the amount of expensive bromine, phosphorus flame retardant, and flame retardant resin can be reduced, so the cost of the laminate can be reduced, and the industrial value is extremely large.

Claims (1)

[Claims] 1. The first step is to impregnate and dry the base material with an undercoat resin, which is a mixture of a phenolic resin initial condensate and a melamine resin mixed with antimony pentoxide (Sb ₂ O ₅ ) sol of 3 to 50% by weight in terms of solid content, flame retardant. A flame-retardant phenolic resin laminate characterized in that a prepreg is produced through a second step of impregnating and drying an oil-modified phenolic resin containing resin into the base material that has passed through the first step, and this prepreg is laminated and molded. Manufacturing method.