Zusammengesetzte Polypropylenfasern und Verfahren zu ihrer Herstellung

Composite polypropylene filaments are made by melt-spinning two propylene polymers each having intrinsic viscosity 0.8-3.5 (in tetralin at 135 DEG C.) in such a way that at least one of the polymers, in the form of unstretched filament, has a beta-orientation of more than 0.2 and intrinsic viscosity more than 1.2, the difference in birefringence of the two polymers being more than 5 x 103. The polymers may be propylene homopolymers or copolymers with vinyl compounds. The polymers may contain light stabilizers, oxidation stabilizers (many specified), fibres such as titanium dioxide, silicon dioxide, plasticizers and materials imparting fluidity, e.g. higher alcohols, esters of fatty acids, hydrocarbon waxes and ketones. The polymers may contain 1-30% of vinyl pyridine polymer or copolymer, 1-20% polyester, or 1-20% of a metal salt of an alkyl ester of sulphoisophthalic acid. The polymers may also contain one or more of compounds of of formulae (R1COO)mM1(OR2)n, (R3COO)m1M2(OH)n or where R1 is C7-C29 alkyl; R2 is C1-C18 alkyl; M1 is Al, Zn or Mg; m and n are 1 or 2 (m + n = 2 or 3); R3 is C7-C29 alkyl; M2 is Zn, Al, Sn or Co; m1 is 1, 2 or 3; n1 is 0, 1, or 2 (m1+n1 = 2 or 3); R4 is C4-C18 alkyl; X is -S-, -SO2-, -SO-, -CH2-, -O-, -CO-; Y is H or OH; M is Ni, Zn, Cu, Co, Pb or Al; B is H2O, NH3, an amine or an N-containing hetero-aromatic compound, and n11 is 0, 1 or 2. The polymers may also contain a sulphophthalic acid alkyl ester, polyethylene, a metal salt of a higher fatty acid, a normal hydrocarbon of mol wt. 500-3000, liquid paraffin, kerosine, tetrachloroethane or compounds of formulae where R is H, alkyl, alkoxy, or acyl; Y is H or OH; Z is -S-, -SO-, -SO2, -CH2-or -CO-; M is Co, Ni, Zn or Al, the above compounds being used alone or with a metal alcoholate of a higher aliphatic acid and/or basic metal salt of a higher fatty acid. Examples describe the spinning of polypropylenes containing (1) 10% liquid paraffin; (2) 7% of 50/50 methyl vinyl pyridine/styrene copolymer; (3) 0.3% nickel distearate and 1% zinc distearate; (4) 0.8% aluminium stearate.