| 摘要 |
1298121 Thermoplastics powders BADISCHE ANILIN- & SODA-FABRIK AG 23 April 1970 [24 April 1969] 19442/70 Headings C3P and C3R [Also in Division B2] A method of making powdered thermoplasts comprises extruding a melt of the thermoplast at 5 to 300 atmospheres and a nozzle speed of 0À2 to 4 m./s. in an annular flow which tapers at a cone angle of 5 to 40 degrees and has an angle of twist of 0 to 60 degrees to form a tube of internal diameter 1 to 30 mm and a wall thickness of 0À2 to 3 mm, and atomizing the extruded tube with 0À5 to 20 kg. per kg. of melt of a gas at 4 to 200 atmospheres, 20‹ to 350‹ C. and a speed of 200 to 700 m./s., the atomizing gas being divided into two streams in a ratio of 1 : 3 to 3 : 1, one stream being guided so as to act on the inside of the molten tube while the outer surface thereof is guided over a distance of 2 to 8 mm., the other stream, which has a thickness of 0À3 to 5 mm, then being guided coaxially with the molten tube so as to impinge thereon at an angle of 15 to 70 degrees to the tube axis, the total gas being guided virtually parallel to the tube axis for a further 1 to 6 mm. Examples describe the atomization of (1-8, 12-14 and 16-20) polyethylene, (21) ethylene vinyl acetate copolymer and (22) ethylene/ n-butyl acrylate copolymer; and compositions comprising (9 and 10) polyethylene and titanium dioxide, (11) polyethylene and carbon black, and (15) polycaprolactam and glass fibres. |
