Patent GB-1215402-A (GB)
Title: Improved conjugate filaments and method for producing same
IPC: B29C48/05
Filed: 1968-02-26
Abstract: 1,215,402. Conjugate filaments. KANEGAFUCHI BOSEKI K.K. and SNIA VISCOSA SOC. NAZIONALE INDUSTRIA APPLICAZIONI VISCOSA S.p.A. 26 Feb., 1968 [25 Feb., 1967 (3)1, No. 9212/68. Heading B5B. A conjugate filament is formed of a first polymeric material and a second polymeric material, the first polymeric material having dyeability properties superior to those of the second polymeric material and the second polymeric material having elastic properties superior to those of the first polymeric material, wherein the said first material is arranged in the cross-section of the filament both adjacently to the outline of said crosssection and in and adjacently to the centre of the said cross-section, and the said polymeric material is spaced both from said outline and said centre and has the greater part of its individual cross-sectional area outside the ideal interface (as hereinafter defined) of the crosssection of the filament, the said second polymeric material having an elasticity modulus at least 10 grams per denier higher than that of said first polymeric material. The ideal interface is defined as a circle concentric to the axis of the filament such that its radius is equal to half the radius of the filament. Figs. 4-11 show filaments according to the invention. Thus the second polymeric material may, as in Figs. 4-9, be disposed in a plurality of portions individually embedded in the said first polymeric material. Alternatively, the second polymeric material may be disposed in an annular portion intermediate between an innermost and an outer surface portion formed by said first polymeric material, and the said annular portion may have a configuration corresponding to that of the outline of the cross-section of the filament, as shown in Figs 10 and 11. In such a filament, the said annular portion is preferably located entirely outside the ideal interface. In the type of filament shown in Figs. 4-9, the said first and second polymeric materials suitably have different indices of refraction, the difference of said indices being of at least 0À05 in at least one direction, thereby giving the filaments a delustered appearance. Filaments of both types desirably contain 10-50% by volume of the second polymeric material, the two polymeric materials differing in elasticity modulus by at least 10 gpd, the first polymer having an elasticity modulus not greater than 35 gpd, the second polymer having an elasticity modulus not lower than 30 gpd, and the elasticity modulus of said second polymer being at least 10 gpd higher than that of said first polymer. Example 1 relates to the spinning of conjugate filaments containing 30% of polyethylene terephthalate as the core-forming material and 70% by volume of polycaprolactam as the sheath-forming material, the filaments being of the form shown in Fig. 10. The undrawn filaments are drawn 3À6 times their original lengths on the snubbing pin heated to 70 C., are false twisted, and the resulting yarn formed into a skein which is boiled in water and air-dried to develop the crimp. Example 2 relates to the spinning of filaments of the form of Fig. 10, using as the core portion either polyethylene terephthalate, polymetaxylylene adipamide, or isotactic polypropylene, the other polymer being polycaprolactam. In Example 3, polycaprolactam and polyethylene terephthalate are conjugate spun at an extrusion ratio of 9 1 by volume and drawn as in Example 1. The filaments are thereafter shrunk at various temperatures and treated to develop the crimp. In Example 4, polyethylene terephthalate is used as the core-forming polymer and as the sheath-forming polymer nylon-6 is used.