| 摘要 |
<p>1,235,901. Finishing fabrics; nets. CONWED CORP. 12 June, 1968 [12 Jan., 1968], No. 28020/68. Headings D1R and DIS. The molecules of a web 20 of polymeric thermoplastic net having two sets of strands 80, 90 in which the strands of one set cross the strands of the other set at an angle to form integral joints, are oriented by heating the net 20, stretching first only the strands of one set of strands along their length while the net is heated, then stretching only the strands of the other set along their length while the net is heated, and cooling the net. As shown, the net 20, e.g. of polypropylene, passes from a roll 22 around idler rolls 28 into a drafting mechanism 12 comprising large heated rolls 34, 36, 38, drafting rolls 46, 48 and idler rolls 32, 42, 44. The rolls 38, 46 are driven at a peripheral speed greater than that at which the rolls 34, 36, 48 are driven to effect longitudinal stretching of the net 20 between the rolls 46, 48. If desired the rolls 42, 44 may be driven at the same speed as the rolls 46, 48, respectively. The rolls 34, 36, 38 are heated by circulation of hot water or oil therethrough and the roll 38 is heated to a lower temperature than the rolls 34, 36 so that the net is slightly cooled to set the resin. The net 20 passes across a space 70 and into a tentering mechanism 14 in which the edges are gripped by endless tenter chains 50, 52 which transversely stretch the net whilst it passes through an oven 40. The oven 40 comprises three sections 74, 76, 78 heated by a hot gas blowing mechanism 82 so that the section 78 is at a higher temperature than the section 76 which is at a higher temperature than the section 74. The net 20 passes over cooling fans 58 and is taken up by a roller 60. At the joints 100 of the oriented net the strands are free of any visibly discernible webbing and are not substantially deformed, Fig. 4.</p> |
