Patent GB-1234892-A (GB)
Title: Composite polyamide/polyester filaments having crimp potential
IPC: D01F8/14
Filed: 1969-03-21
Abstract: 1,234,892. Composite polyamide/polyester filaments having crimp potential. KANEGAFUCHI BOSEKI K.K., and SNIA VISCOSA SOC. NAZIONALE INDUSTRIA APPLICAZIONI VISCOSA S.p.A. 21 March, 1969 [21 March, 1968; 17 April, 1968; 20 April, 1968], No. 15027/69. Heading B5B. A composite filament having a high capacity for developing crimps comprises at least two different synthetic linear polymer components bonded in eccentric sheath-core relationship, one component being a polyester comprising mainly polyethylene terephthalate, e.g. at least 95% by weight polyethylene terephthalate, and another component being a highly shrinkable polyamide having a shrinkage in boiling water of at least 15% and not exceeding 80% and the core component forming from 5 to 50% by weight of the filament. The polyamide may be a high molecular weight polyamide having an intrinsic viscosity in meta cresol at 30 C. of above 1À15. The polyamide may be a copolyamide containing 5 to 30% by weight of a comonomer constituent. The copolyamide may contain less than 5% by weight of the comonomer constituent and may have an intrinsic viscosity of less than 1À15 in meta cresol at 30 C. The polyester may form the core component and the polyamide the sheath component of the composite filament. The shrinkage, degree of eccentricity and proportion by weight of the core component in the filament may satisfy the formulµ: 3À8 # (1À4a<SP>2</SP> + 50b + 200 #c) x 10<SP>-3</SP> # 7À0 and 80 # a # 15 and 10 # c # 50 in which a is the percentage shrinkage in boiling water of the polyamide component, b represents the degree of eccentricity expressed by the formula b = R 1 /R 2  x 100 (in which R 1  is the distance from the centre of gravity of the core component to the centre of the filament and R 2  is the radius of the filament) and c is the percentage by weight of the core component based on the weight of the filament. b may be at least 5%. The composite filament may have at least two cores and may satisfy the equations: 1À2 x 10<SP>-1</SP> # NS (D/R)<SP>2</SP>(1 + E) # 10À1 x 10-1 E # 0À1 and S # 1À1 in which D represents the arithmetic mean of the diameters of each core when the cores are circular in cross-section or, in the ease of non-circular cores, the diameters of circles equal in area to the cross-sectional area of each core; R is the diameter of the filament, N is the number of cores, E is the ratio of the initial modulus of the polyamide to that of the polyester and S is the ratio of the shrinkability of the polyamide to that of the polyester. The sheath of the composite filament may comprise a homopolyamide component and a copolyamide component bonded to each other along the length of the filament and the core component may be wholly within the homopolyamide component. In such composite filaments the angle between a line joining the centre of gravity of the polyester core component and that of the homopolyamide component, and a line joining the centre of gravity of the polyester component and the copolyamide component may be from 90 degrees to 180 degrees. The homopolyamide component in the composite filaments may be nylon 6 or nylon 66 and the copolyamide may be poly (caproamide/hexamethylene adipamide), poly (caproamide/hexamethylene isophthalamide) or poly (hexamethyleneadipamide/hexamethylene sebacamide).