| 摘要 |
Cellular polystyrene is prepared by polymerizing styrene monomer, sufficient of which is included for polymerization and as a solvent required for particle absorption and holding of the foaming agent in the presence of a watersoluble nitrite which is added when the rate of conversion is less than 98% in an amount of 0.0003 to 0.05% by weight of the total styrene, and adding an aliphatic hydrocarbon having 3 or 4 carbon atoms as a foaming agent, when the rate of conversion of styrene monomer is 80 to 98% of completion, the interior of the polymerization system being maintained under pressure, and adjustment being made to the condition of dispersion and agitation of the system so as to avoid any defective portions on the particle surfaces and to impart to the polystyrene approximate true roundness, with an average particle diameter of 0.40 to 1.00 mm. and degree of foaming of 60 to 400 c.c./10 g.; mixing 100 parts by weight of the particles with 0.5 to 10.0 parts by weight of calcined perlite in particle form having an average particle size of less than 30 m ; and extruding the mixture under high temperature. Preferred foaming agents are propane and butane whilst sodium and potassium nitrites are the preferred nitrites. |
