| 摘要 |
1,239,099. Foamed polystyrene articles with hardened surface. OVERMAN A.B. 4 July, 1969 [8 July, 1968], No. 33803/69. Heading B5A. A cellular polystyrene article with a hardened surface is made by coating the inside of a mould with a mixture of sulphur and a substance capable of reacting with expanded polystyrene and sulphur at a temperature of 100-110‹ C. to form a hard material, filling the mould with expandable polystyrene, closing the mould and heating to expand the polystyrene and form a hard layer on its surface. The substance which reacts with the sulphur and polystyrene may be a hydrocarbon oil or a mixture of such oils e.g. a fuel oil, a vegetable oil e.g. linseed oil, an animal oil or wood or coal tar. A solvent for polystyrene, e.g. styrene and a thermoplastic resin may also be added to the mixture. The proportion of sulphur in the mixture should be 1À5-70 wt. per cent preferably 25-50 wt. per cent. The polystyrene is preferably expanded by steam or hot air at a temp. of 100-110‹ C. and a reinforcing layer comprising, for example, a textile fabric, woven glass cloth, jute fabric or asbestos fibres may be placed over the coating before foaming. |
