ES355057A1 - A method for Regulating Development of Crimp in Conjugate Filaments - Google Patents

Abstract

The development of crimps in composite filaments having latent crimpability and obtained by simultaneously melt-spinning at least two different thermoplastic synthetic organic to form composite filaments of the sideby-side or of the eccentric sheath-core type and drawing the composite filaments thereby formed is regulated by subjecting the filaments to a preliminary heating step in a primary heating zone at a suitable temperature and under a restrained condition such that the filaments do not develop crimps. The latent crimpability of the filaments is thereby reduced. The filaments are then further heated in a secondary heating zone in a tensionless condition, whereby they develop crimps to the desired degree. The temperature in the primary heating zone is selected according to the desired number of crimps per 25 mm. length of each of the filaments after the treatment in the secondary heating zone. The primary and secondary zones may have the same heating systems and the temperature in the primary zone may be the same as or lower than that in the secondary zone. The primary zone may have a dry heating system and the secondary zone may have a wet heating system of hot water or steam and the temperature in the primary zone may be up to 90 C. higher than that in the secondary zone. Both zones may have hot water heating systems. The primary zone may be a metal tube heating system and the secondary zone may be a jet crimper. The heating medium in both the said systems may be steam. When both the zones have hot water heating systems, the temperature in the primary zone may be 20 to 100 C. and that in the secondary zone about 100 C. When the primary zone is a metal tube heating system or a heated roller system and the secondary zone a jet crimper system or a cylindrical means for developing crimps, the temperature in the primary zone may be 20 to 180 C. and in the secondary zone about 180 C. Alternatively, the temperature in the primary zone may be 130 to 190 C. and that in the secondary zone about 190 C. The components of the composite filaments may be a homopolyamide and a copolyamide, a polyester and a polyester-ether, a polyamide and a polyester or polyolefins having different shrinkabilities or different intrinsic viscosities. One component may be nylon-6 and the other a copolymer of #-caprolactam and hexamethylene diammonium isophthalate or hexamethylene diammonium terephthalate. One component may be polyethylene terephthalate and the other polyethylene paraoxybenzoate or a copolymer of polyethylene terephthalate with polyethylene isophthalate or with polyethylene paraoxybenzoate. One component may be nylon-6 and the other polyethylene terephthalate.