| 摘要 |
1,226,191. Blow-moulding; expanded walls. CHEMISCHE WERKE HULS A.G. 9 Aug., 1968 [12 Aug., 1967], No. 38189/68. Heading B5A. Blow-moulded hollow articles are produced from thermoplastics containing an expanding agent by extruding a tubular parison, introducing it into the blow-mould, and inflating it therein, in a chamber at a pressure higher than the expansion pressure of the expanding agent and then decreasing the pressure during or after the inflation to expand the expanding agent while the article is still thermoplastic. Pressure decrease is effected after inflation if a smooth-walled article is desired or during inflation if no unexpanded skin is desired since this will avoid contact with the mould wall which would cause skin formation. |
