Abstract: A foamable composition for preparing inorganic light weight foam includes an inorganic powder and vinyl chloride-based resin as main components, and an organic solvent and a foaming agent. The vinyl chloride-based resin is a higher molecular weight resin made by suspension-polymerization or mass-polymerization, and has an average degree of polymerization (p) of 1300 to 10000 as defined by JIS K-6721-1959. The ratio by weight of the inorganic powder to the vinyl chloride-based resin ranges from 50:50 to 85:15. The organic solvent has a solubility parameter (.delta.) of 7 to 10, and a boiling point of 80.degree. C. to 140.degree. C. The ratio by weight of the organic solvent to the total amount of the inorganic powder and the vinyl chloride-based resin ranges from 60:40 to 40:60. The inorganic powder and vinyl chloride-based resin components are kneaded at between 140 and 200 degrees Celsius, while applying a shearing force on the kneaded composition.

Abstract: A method of preparing a foamable polyvinyl system resin composition which renders a non-flammable, high strength to weight ratio foam product comprises, reacting at least 0.05 parts by weight of an organic radical initiator per 1 part by weight of polyvinyl system resin with the components consisting essentially of (a) at least one polyvinyl system resin (b) 2-100 parts by weight of at least one inorganic filler per 1 part by weight of polyvinyl system resin (c) an effective amount of at least one blowing agent.