Modified polyphenylene ether resin foam sheet

Abstract

This invention provides a foamed sheet, which is a modified polyphenylene ether resin foamed sheet with good formability and processability. It exhibits very low relative permittivity and dielectric loss factor at high frequencies, and possesses self-extinguishing or flame-retardant properties, along with excellent surface characteristics. The modified polyphenylene ether resin foamed sheet of this invention is produced by foaming a modified polyphenylene ether resin containing both a halogen-based flame retardant and a phosphorus-based flame retardant with a weight-average molecular weight of 1,000 to 1,000,000 as flame retardants. The average bubble diameter of the bubbles in the modified polyphenylene ether resin foamed sheet is 1–30 μm, and the bubble number density is 1.8 × 10⁴ to 9 × 10⁸ bubbles / mm³.