| 摘要 |
PURPOSE:To obtain the titled particles having expanding properties and improved weather and solvent resistance, by copolymerizing a specific amount of a vinyl aromatic monomer with nuclear material resin particles consisting of specific amounts of vinyl chloride (co)polymer and a polyolefin polymer, and incorporating a foaming agent therein. CONSTITUTION:(A) 10-50pts.wt. nuclear material resin particles consisting of 70-100wt% vinyl chloride (co)polymer and 30-0wt% polyolefin polymer, preferably polyethylene are suspended in an aqueous medium containing a dispersing agent, e.g. a polyacrylic acid salt, and (B) 90-50pts.wt. vinyl aromatic monomer, e.g. styrene, is absorbed in the above-mentioned particles and polymerized in the presence of a polymerization catalyst, e.g. benzoyl peroxide. A gaseous or liquid foaming agent, e.g. propane, is added before, during or at the completion of the polymerization to give the aimed resin particles containing the foaming agent therein. EFFECT:Self-extinguishing properties can be imparted to the particles even in a small amount of a flame retardant.
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