IMPROVED PROPERTIES OF FOAMED POLYMETHYL METHACRYLATES BY USING METHACRYLAMIDES Russian patent published in 2021 - IPC C08F220/14 C08F220/18 C08F265/06 C08J9/02 C08J9/04 

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to a method of producing foamed polymethyl methacrylate and to foamed polymethyl methacrylate, which can be used as weather-resistant insulation material, as base material in laminar composites, in lightweight structures, as packing material, as absorbers or energy dampers in accident protection elements, in architectural and structural elements, as a diffuser in the field of lighting equipment, in furniture production, in shipbuilding, in automotive industry, in aircraft engineering or in model building. Method of producing foamed polymethyl methacrylate involves polymerising a composition, containing from 0.2 to 2.0 wt % azo initiator, 0 to 5 wt % of the compound with one to five mercaptan groups as a regulator, from 70 to 99.8 wt % of mixture of monomers, from 0 to 10 wt % of a cross-linking agent, selected from a group consisting of glycol di- or trimethacrylate. Polymerisation is carried out at temperature ranging from 20 to 100 °C, then foaming the mass at temperature within 130 to 250 °C for 35 minutes to 1 hour. Mixture of monomers contains from 70 to 95 wt % methyl methacrylate, 0.1 to 5 wt % alkyl acrylate with 1–12 carbon atoms in alkyl residue, from 5 to 10 wt % alkyl methacrylate with 2–12 carbon atoms in alkyl residue, from 0.5 to 10 wt % N-alkyl methacrylamide with 1–12 carbon atoms in the alkyl group. At the beginning of polymerisation the mixture of monomers contains polymethylmethacrylate in amount of up to 80 wt %. Foam polymethyl methacrylate obtained by the above method has a density in range from 50 to 350 kg/m³.

EFFECT: invention enables to obtain foam polymethyl methacrylate, characterized by high compression strength.

10 cl, 10 tbl, 9 ex