Expandable polystyrene resin particles and method for producing the same

摘要

A blowing agent is infiltrated into polystyrene resin particles dispersed in an aqueous suspension. Before or during infiltration, a flame retardant solution obtained by dissolving 33-1,000 parts by weight of a powdery flame retardant and 20-200 parts by weight of a flame retardant aid having a 1-hour half-life temperature of 100-250° C. in 100 parts by weight of a plasticizer is supplied to the aqueous suspension to infiltrate the flame retardant and the flame retardant aid into the particles, producing expandable polystyrene resin particles. By dissolving the flame retardant, which doesn't accumulate in the living body and has satisfactory handleability, in a plasticizer, the flame retardant can be evenly infiltrated into resin particles. Consequently, expansion of the expandable particles doesn't result in unevenness of cell density and the particles have excellent heat-fusibility to one another during molding, and molded foam having excellent flame retardancy and heat resistance can be obtained.

主权项

1. Expandable polystyrene resin particles, which are obtained by supplying a flame-retardant solution into an aqueous suspension before or during impregnating polystyrene resin particles dispersed in the aqueous suspension with a blowing agent, in which the flame-retardant solution is prepared by dissolving in a liquid state plasticizer 33 to 1000 parts by weight of powdery flame retardant relative to 100 parts by weight of the plasticizer and further 20 to 200 parts by weight of a flame retardant aid having one-hour half-life temperature of 100° C. to 250° C. relative to 100 parts by weight of the plasticizer, and
impregnating the polystyrene resin particles with the flame retardant and the flame retardant aid, wherein the flame retardant comprises tetrabromocyclooctane that is dry blended with silica fine powders with a Henschel mixer and preliminarily dispersed by silica fine powders, the silica fine powders have the specific surface area of 170 to 330 m2/g, the silica fine powders are contained in an amount of 0.3 to 1.5 parts by weight relative to 98.5 to 99.7 parts by weight of the tetrabromocyclooctane, and the flame retardant is absorbed into the central portion of the polystyrene resin particles and the silica fine powders are not absorbed into the polystyrene resin particles.