| 摘要 |
The recovery from compression of polypropylene fibres is enhanced by drawing the as-spun fibres and thereafter heating them in an untensioned state at a temperature from 140 DEG C. up to the melting point of the fibres for at least one second. The fibres may be stretched as part of the spinning process or after wind-up. Drawing may be effected at temperatures above 80 DEG C., and fibres may be drawn from 3x to 10x. Subsequent to drawing and prior to heating the fibres may be bulked, either by mechanical crimping or by subjection to a heated turbulent fluid. The fibres may be cut to staple fibres subsequent to drawing and prior to heating, which is suitably carried out for a period of 1-30 minutes. Polypropylene fibres so made have a recovery from compression of more than 65%, a denier per filament of 1 to 40, a tenacity of at least 2,5 g./denier and an elongation at break of 20-150%, desirably 30-60%. Specified materials include highly crystalline polypropylene, block copolymers of the crystalline and non-crystalline forms and mixtures of polypropylene with 1-20% of polyamides, polyesters and vinyl polymers and copolymers, and graft and block copolymers of polypropylene and readily dyeable monomers. Fibres may be made by melt, dry, or wet spinning. The resilience of the fibres makes them especially suitable for use as stuffing, or in carpets. Specification 905,895 and U.S.A. Specification 2,747,233 are referred to.
|
