GB1370378A - Production of foam plastics bodies - Google Patents

Abstract

1370378 Moulding foamed articles BAYER AG 18 Nov 1971 [18 Nov 1970] 53532/71 Heading B5A [Also in Division C3] In a method of producing foamed plastics articles, the mould, after having been filled with liquid foamable reactants, is acted upon externally, and at least partially sealed, by a fluid medium under a pressure of at least 0À2 kg./cm.<SP>2</SP> above the foaming pressure inside the mould at a given moment. Using the apparatus shown in Fig. 1, a mould 3 is placed inside a pressure vessel 1, and is evacuated through pipe 18, the pressure registering device 19 associated with the mould interior electronically activating the drive means for evacuating the pressure vessel until the pressure registering means 28 associated with the pressure vessel shows a pressure of about 0À3 atm. above that in the mould; the mould is then filled with liquid foamable reactants through pipe 13, and, as the foaming pressure increases, the pressure outside the mould is increased by feeding pressurized fluid from a reservoir 40 into the pressure vessel 1, the pressure being electronically controlled in relation to the readings on the pressure registering means 19, 28. Using this method obviates the need for heavy duty moulds needed to withstand high foaming pressures. In a further embodiment (Fig. 2, not shown) the pressure is controlled by an experimentally determined programme.