초록 ▼

Articles are blow moulded from thermoplastic polymeric materials containing high proportions of fillers such as glass fibres. The method comprises extruding the filled polymeric material through a die having a mandrel for constraining the material into a tubular shape; coextruding between the die an

Articles are blow moulded from thermoplastic polymeric materials containing high proportions of fillers such as glass fibres. The method comprises extruding the filled polymeric material through a die having a mandrel for constraining the material into a tubular shape; coextruding between the die and the outer surface of the material, a liquid having a freezing temperature lower than that of the material; cooling the liquid and the outer surface of the material during their passage through the die to a temperature below the freezing temperature of the material but above the freezing temperature of the liquid while maintaining the inner surface of the material molten; squeezing the extrudate at suitable intervals to fuse the molten inner surface together and thereby seal discrete lengths; and inflating the sealed lengths to conform to a surrounding mould to produce laminar shapes which are then foamed-filled to give stiff panels.

대표청구항 ▼

A method for producing a shaped article which comprises extruding a thermoplastic polymeric material, initially in a molten state, through a die having a mandrel for constraining the material into a tubular shape and producing thereby a tubular extrudate having an outer surface and an inner surface;

A method for producing a shaped article which comprises extruding a thermoplastic polymeric material, initially in a molten state, through a die having a mandrel for constraining the material into a tubular shape and producing thereby a tubular extrudate having an outer surface and an inner surface; coextruding between the die and the outer surface of the polymeric material, a liquid having a freezing temperature lower than that of the polymeric material; cooling the liquid and the outer surface of the polymeric material during their passage through the die, to a temperature below the freezing temperature of the polymeric material but above the freezing temperature of the liquid, while maintaining the inner surface of the polymeric material molten; squeezing the extrudate at suitable intervals to fuse the molten inner surface together and thereby seal discrete lengths; and inflating a sealed length to conform to a surrounding mould, thereby to produce the shaped article, characterised in that the method is applied to a thermoplastic material containing a filler, the ratio of filler to thermoplastic material being at least 15:85 by weight, and that the sealed length of extrudate is moulded into an article with two closely-spaced substantially parallel walls enclosing a volume therebetween, a foamable composition is injected into the enclosed volume and the composition is allowed or caused to foam while the article is held within a constraining means constructed to prevent outward displacement of the spaced-apart walls by pressure from the foaming composition.