Soft ethylenic polymer foams

US4129530A · kind A · utility

Assignee

• THE DOW CHEMICAL COMPANY · US

Inventors

• Chung P. Park · Baden-Baden, DE
• John Corbett · Sydney, AU
• Warren H. Griffin · Saginaw, US

Key dates

• Filing date: Dec 19, 1977
• Grant date: Dec 12, 1978
• Expiry date: Dec 19, 1997

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S264/05
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

Low density, closed cell, soft foam products having dimensional stability are made from ethylenic resins having low stiffness, especially comprising copolymers consisting essentially of ethylene and monoethylenically unsaturated non-ionic comonomers, by release to lower pressure of a flowable, foamable gel under pressure, e.g., by extrusion foaming, wherein the gel comprises the ethylenic polymer and a volatile mixed blowing agent. The starting polymers are preferably copolymers of ethylene and vinyl acetate having stiffness less than about 20,000 psi. The mixed blowing agents are particularly characterized as mixtures of dichlorodifluoromethane and at least one fluorocarbon constituent A, as defined. Exemplary mixtures contain (I) dichlorodifluoromethane and (II) from 35 to 50 percent chloropentafluoroethane, octafluoropropane or octafluorocyclobutane based on the mixtures of I and II.