FOAMABLE POLYSTYRENE PRODUCTION PROCESS Russian patent published in 2007 - IPC C08F212/08 C08F2/18 

FIELD: polymer production.

SUBSTANCE: high molecular-weight foamable polystyrene is produced via two-step styrene polymerization, wherein, (i) in the first step, styrene is subjected to prepolymerization in presence of primary process initiator, fire-retardant - hexabromocyclododecane and its synergist dicumyl peroxide, chain growth regulator, and secondary initiator - O,O-tert-amyl-O-(2-hexyl) monoproxycarbonate, and (ii) in the second step, suspension polymerization proceeds in aqueous medium in presence of stabilizer - polyvinyl alcohol, chain growth regulator, third initiator - tert-butyl perbenzoate, and foaming agent. Invention is characterized by that, as primary process initiator, 2,5-bis(2-ethylhexanoyl-peroxy)-2,5-dimethylhexane is utilized and process is conducted at weight ratio of all three initiators 0.956:1:(1.14-2.5), respectively, until polymer with relative viscosity 2.1-2.3 is obtained.

EFFECT: enhanced process efficiency.

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