JPH0360860B2 - - 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. BACKGROUND OF THE INVENTION Recently, as the use of flame-retardant phenolic resin laminates as electric insulating substrates in consumer electronics has increased, the demand for high quality and low cost has become higher and higher. In order to obtain a flame-retardant phenolic resin laminate with advanced electrical properties, the process of impregnating and drying the base material with a thermosetting resin is repeated twice, as an undercoat and a topcoat, in the preparation stage of the prepreg to be laminated and molded. There is a way. Conventionally, a base material is impregnated with an undercoat resin that is a mixture of a phenolic resin initial condensate and a melamine resin, and then dried.
Furthermore, a prepreg was prepared by impregnating and drying an oil-modified phenolic resin varnish containing a flame retardant and a flame retardant resin as a top coat resin. Problems to be solved by the invention Conventional methods ensure flame retardancy (UL-94-V
-O), the undercoat resin is a mixed resin of a phenolic resin initial condensate and a melamine resin, and the topcoat resin is a flame-retardant resin such as brominated epoxy resin, tetrabromobisphenol A, triphenylphosphine, etc. Because it contained a large amount of flame retardants such as bromine compounds such as esters and phosphorus compounds, the resulting laminate had poor interlayer adhesion, poor room-temperature punching workability and heat resistance, and was even 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 The present invention has been made to achieve the above-mentioned object, and includes a difficult first step of impregnating and drying a base material with an undercoat resin that is a mixture of a phenolic resin initial condensate and a melamine resin. A prepreg is created through a second step in which the base material that has undergone the first step is impregnated with a top coat resin containing 2 to 20% by weight of antimony pentoxide sol in terms of solid content in an oil-modified phenolic resin containing a combustion resin and dried. , which is characterized by being laminated and molded. 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, in the conventional method, since the content of flame retardant in the top coat resin is high, the adhesion between the layers of the laminate is weak, which causes a decrease in room temperature punching workability and heat resistance. Therefore, by adding antimony pentoxide sol, which has a large flame retardant effect, the use of flame retardant resin as well as bromine and phosphorus flame retardants in the top coat resin can be reduced, and the transparency of the laminate can also be maintained. However, if the antimony pentoxide sol is less than 2% by weight in the top coat resin, the effect of ensuring flame retardancy (UL-94V-O) and reducing the use of bromine-based and phosphorus-based flame retardants cannot be achieved. Nakatsuta. Furthermore, if the amount exceeds 20% by weight of the topcoat resin, the laminate becomes opaque, leading to quality problems. A preferred amount is 3 to 10% by weight. Examples Next, examples of the present invention will be described together with comparative examples and conventional examples. () Production of tung oil-modified phenolic resin 366 g of cresol, 450 g of tung oil, and 0.47 g of paratoluenesulfonic acid were charged into a flask with a condenser and reacted at 80°C for 90 minutes with stirring, and then 307 g of phenol, 280 g of 86% paraform, and 25%
After adding 21g of ammonia water and reacting for 4 hours, dehydration was performed for about 1 hour under reduced pressure, and methanol
362 g and 356 g of toluene were added and cooled. The nonvolatile content of this resin was 50%. () Production of flame retardant resin 628g of brominated epoxy resin and 23.2g of diisopropyl phosphate were placed in a flask and heated to 80°C.
After reacting for 3 hours, 24.8g of diaminodiphenylmethane was added, the reaction was continued for 1 hour at 80℃, and then 142g of triphenyl phosphate was added.
Add and dissolve. () Manufacture of laminate board The resin obtained above was mixed with antimony pentoxide sol (organic solvent dispersion) at the blending ratio (% by weight) shown in Table 1 to prepare a top coat resin. first,
11 mils kraft paper is impregnated with an undercoat resin that is a mixture of a phenolic resin initial condensate and a melamine resin (phenolic resin initial condensate/melamine resin = 70/30) and dried to obtain coated paper with a resin content of 10 to 15% by weight. Ta. Furthermore, this coated paper was impregnated with the top coating resin shown in Table 1 and dried to produce a prepreg having a resin content of 48 to 51% by weight. A predetermined number of sheets of this prepreg were laminated with copper foil on one surface of the prepreg, and molded for 60 minutes at 160° C. and under heat and pressure of 100 kg/cm ² to obtain a single-sided copper-clad laminate with a thickness of 1.6 mm. Table 2 shows the characteristics test results of this copper-clad laminate.

【table】

【table】

[Table] Effects of the Invention As described above, according to the present invention, as is clear from Tables 1 and 2, while maintaining flame retardancy, it can be used together with bromine-based and phosphorus-based flame retardants in the top coat resin. It was also possible to reduce the amount of combustible resin and increase the amount of oil-modified phenolic resin, thereby improving heat resistance and punching workability. In addition, by adding antimony pentoxide sol to the top coat resin, the amount of expensive bromine, phosphorus flame retardants, and flame retardant resins can be reduced.
The cost can be reduced and the industrial value is extremely large.

Claims (1)

[Claims] 1 The first step of impregnating and drying the base material with an undercoat resin that is a mixture of a phenolic resin initial condensate and a melamine resin, and adding 2 to 20% of antimony pentoxide sol in terms of solid content to the oil-modified phenolic resin containing a flame-retardant resin.
A method for producing a flame-retardant phenolic resin laminate, characterized in that a prepreg is produced through a second step of impregnating and drying the base material that has undergone the first step with a top coat resin containing % by weight, and the prepreg is laminated and molded. .