METHOD OF PRODUCING FOAMABLE POLYSTYRENE GRANULATE Russian patent published in 2012 - IPC C08J9/00 C08J9/14 C08K3/00 C08K3/04 

FIELD: chemistry.

SUBSTANCE: method involves a step for mixing a carbon additive and a foaming agent with molten polystyrene, homogenisation of the mixture, cooling said mixture to extrusion temperature, extrusion and granulation in conditions which prevent foaming. The ratio of the molar quantity of the foaming agent fed to the specific throughput of the apparatus in the mixing zone (Ks) is kept in the range of 0.08-0.23, while maintaining temperature difference at the input and output of the homogenisation step and cooling step in the range of 30-70°C. The carbon additive used is thermally expanded modified graphite in powder form, which contains separate particles with thickness 0.35-5.0 nm and bunches of particles consisting of 10-30 particles (sheets) with average lateral particle (sheet) size of 5-100 mcm, taken in amount of 0.1-0.6% of the total weight of the load.

EFFECT: use of thermally expanded modified graphite in said amount enables to lower thermal conductivity without deterioration of strength characteristics and simultaneous reduction of water absorption of foamed articles which are made from the foamed polystyrene granulate.

2 cl, 1 tbl, 10 ex