FOAMING AGENT MASTER BATCH FOR VINYL CHLORIDE RESIN COMPOSITION

PROBLEM TO BE SOLVED: To obtain the subject master batch that can form fine foam and highly dispersed foam cells with an extrusion foaming machine and is useful as an extrusion coating composition for wire cables by formulating a plasticizer, a stabilizer and a foaming agent in a specific proportion to a specific vinyl chloride copolymer resin. SOLUTION: This foaming master batch comprises (A) 100 pts.wt. of an ethylene-vinyl chloride copolymer (for example, having an average polymerization degree of 400-2,000), (B) 10-100 pts.wt. of a plasticizer, for example, a phthalic ester, (C) 1-5 pts.wt. of a stabilizer, for example, a barium or lead stabilizer and (D) 1-20 pts.wt. of a foaming agent selected from benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, toluene-2,4-disulfonylhydrazide.