| 摘要 |
1,157,299. Extruding fibrous sheets and tubes; filamentarys tructures. UGINE KUHLMANN. 24 April, 1967 [25 April, 1966], No. 18770/67. Headings B5A and B5B [Also in Division D1] A fibrous thermoplastic material is made by forming a thermoplastic mass containing gas bubbles, bursting the bubbles by heating the mass and stretching the mass. Preferably the material is formed by extruding the bubble-containing thermoplastic mass through a heated die so as to burst the bubbles then stretching the extrudate after it has left the die. The bubbles can be introduced by use of a gaseous, liquid or solid blowing agent, e.g. sodium bicarbonate, azodicarbonamide or dinitropentamethylenetetramine or by injecting a gas under pressure into the thermoplastic mass. The mass can be polystyrene, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, poly vinyl chloride, polymethylmethacrylate or polyethylene or a mixture thereof. The mass may also contain a paraffin oil. The extrusion die can be flat or circular, e.g. to produce sheets or tubular articles and heated to at least 180‹ C. to burst the bubbles. The stretch ratio can be 3 : 1 to 6: 1 in the axial and transverse directions in relation to the longitudinal axis of the die. The fibrous sheets formed can be shaped with or without heating. A polystyrene fibrous product has a density of 0À3-0À6 g/cc. and may be 0À3 to 0À8 mm. thick or 2 to 3 mm. thick. |
