| 摘要 |
1,176,238. Moulding olefin polymer foams. BADISCHE ANILIN- & SODA-FABRIK A.G. 27 April, 1967 [28 April, 1968; 23 Aug., 1966], No. 19431/67. Heading B5A. Mouldings of expanded olefin polymers are formed by heating expanded particles of crosslinked crystalline homo- or co-polymers of olefins having two or three carbon atoms in a closed mould from which gases and liquid can excape but from which the expanded particles cannot escape. The particles are preferably compressed by 5-70 degrees volume per cent by moving two opposed mould sides towards the centre of the mould cavity. The polymer must have an X-ray crystallinity greater than 25% at 25‹ C. and may be polyethylene, polypropylene, a copolymer of ethylene and propylene or a copolymer of ethylene with various vinyl compounds especially acrylic esters. It may contain fillers, reinforcements, dyes, flame retardants, lubricants or other polymers and the degree of crosslinking may be increased by irradiation with X-rays or an electron beam. The expanded particles preferably have diameters of between 3 and 40 mm. Heating during the moulding process may be carried out by immersing the mould in a bath of liquid, by passing a heated gas through the mould or by introducing a heated gas into the mould cavity, the pipes being removed before compressing the particles. |
