| 摘要 |
A fabric having 10-40% stretch in one direction, due to crimp interchange produced by heat treatment with the yarns in the other direction under tension, is woven from thermoplastic spun yarns of cellulose triacetate, nylon 6 or 66, or isotactic polypropylene. The heat treatment is at 20-80 DEG C. below melting point for 30 secs. followed by cooling to 50-200 DEG C. below melting point before removing the tension; the fabric must not have been previously heated to within 50-120 DEG of the melting point, and the heat treatment temperature should be at least 10 DEG higher than any temperature previously experienced by the fabric. To produce weftwise stretch, the fabric may be treated by hot air in a stenter which has tension bars that will withstand 40% warp stretch without bending and which has no pins or other means to restrict weftwise contraction, there being also a cold air fan to cool the fabric. |
