FIELD: chemistry.
SUBSTANCE: present invention relates to a method for the production of foamed polymer compositions and to foamed polymer compositions containing vinyl aromatic polymers, which have improved flame retardant characteristics and improved processing ability. A method is proposed for the production of a foamed polymer composition containing: a) a polymer matrix containing vinyl aromatic polymer, b) from 1 wt. % to 7 wt. % per the polymer matrix (a) of an additive impervious to heat radiation, c) from 1.2 wt. % to 2.3 wt. % per the polymer matrix (a) of at least one non-polymer brominated flame retardant additive, d) from 0.25 wt. % to 0.8 wt. % per the polymer matrix (a) of at least one brominated polymer containing at least 50 wt. % of bromine, e) from 0.1 wt. % to 0.5 wt. % per the polymer matrix (a) of a synergetic flame retardant additive, f) from 1 wt. % to 10 wt. % of at least one foamer. In this case, the additive impervious to heat radiation is a carbon-containing compound selected from coke or graphite, where graphite is in the form of particles, which have a size D90 measured using a laser wet particle size analyzer of a Malvern 2000 type, according to ISO 13320 method, from 0.05 mcm to 100 mcm and a surface area from 5 m2/g to 50 m2/g, where the surface area is measured according to ASTM D-3037-89 and indicated as BET. The method is carried out in continuous mass, and it includes following successive stages: mixing of vinyl aromatic polymer in the form of granules, or powder, or in an already molten state with the additive impervious to heat radiation, as it is, or in the form of a masterbatch, and with any additional additives to form a polymer mixture, if it is not in the already molten state, bringing the polymer mixture to a temperature above the melting point of vinyl aromatic polymer, addition to the molten polymer mixture of at least one foamer, flame retardant additives or mixtures thereof, and any additional additives to form a vinyl aromatic polymer composition, mixing of the polymer composition obtained in this way, using static or dynamic mixing elements, direction of the polymer composition after mixing into a cutting chain device with a system of spray nozzles or into a chain device, in which polymer is cut in a granulation chamber, in which foamed granules are fully submerged in water, and water pressure in the cutting chamber is more than 300 kPa (3 bar). In this case, the foamed polymer composition for the manufacture of foamed products contains: a) a polymer matrix containing vinyl aromatic polymer, b) from 1 wt. % to 7 wt. % per the polymer matrix (a) of an additive impervious to heat radiation, including coke, c) from 1.2 wt. % to 2.3 wt. % per the polymer matrix (a) of at least one non-polymer brominated flame retardant additive selected from bisphenol A derivatives and a mixture thereof, d) from 0.25 wt. % to 0.8 wt. % per the polymer matrix (a) of at least one brominated polymer containing at least 50 wt. % of bromine selected from brominated polystyrene, copolymer of tetrabrombisphenol A-2,2-bis-(4-(2,3-epoxypropoxy)-dibromophenyl)propane, brominated polybutadiene, and brominated block copolymers of styrene and butadiene, and mixtures thereof, e) from 0.1 wt. % to 0.5 wt. % per the polymer matrix (a) of a synergetic flame retardant additive, f) from 1 wt. % to 10 wt. % of at least one foamer.
EFFECT: lower density of compositions containing various combinations of flame retardant additives and decrease in the concentration of released hydrobromic acid, so that corrosion problems in industrial installations are eliminated.
28 cl, 8 ex, 1 tbl
