Fibers suitable for the production of nonwoven fabrics having improved strength and softness characteristics
AssigneeMontell North America Inc.
InventorsLeonardo Pinoca, Renato Africano, Leonardo Spagnoli
Life of this patent
Estimating the term…
Abstract
Disclosed is a drawn, polyolefin fiber useful for nonwoven fabrics, the thermobonding index of said fiber being 4.5-9 Newtons, and the flexibility index thereof being 1020-1500. The fiber is composed of a blend of specified polymers. Also disclosed is a process for making the fiber by spinning the blend from a die hole having at the output end a diameter less than 0.5 mm, and drawing the resulting fiber at a draw ratio of 1.1 to 1.8.
Claims9
A drawn, polyolefin fiber suitable for nonwoven fabrics, the composition of said fiber comprising an olefin polymer blend consisting essentially of (all parts and %s being by weight):
- 1) 50 to 80 parts of a crystalline polymer selected from the group consisting of a propylene homopolymer having an isotactic index greater than 90, and a random copolymer of propylene and an olefin selected from the group consisting of ethylene and C.sub.4 -C.sub.8 .alpha.-olefins, said olefin being 0.05 to 15% of the copolymer;
- and
- 2) 20 to 50 parts of a heterophasic polyolefin composition comprising:
- a) 20 to 70 parts of a propylene polymer of the group consisting of a propylene homopolymer and a random copolymer of propylene and an olefin selected from the group consisting of ethylene and C.sub.4 -C.sub.8 .alpha.-olefins, said olefin being 0.5 to 10% of the copolymer of this group;
- and
- b) 30 to 80 parts of a copolymer of ethylene and an olefin selected from the group consisting of propylene and C.sub.4 -C.sub.8 .alpha.-olefins, said copolymer being soluble in xylene at 25.degree. C., the intrinsic viscosity of said copolymer, when its ethylene content is 40 to 70% of the copolymer, being lower than or equal to 1.5 dl/g, and, when its ethylene content is less than 40% of the copolymer, being lower than or equal to 2.3 dl/g;
- said fiber having been obtained by spinning said olefin polymer blend in a spinning apparatus with real or equivalent output hole diameter of less than 0.5 mm, and then drawing the resulting fiber out with a draw-ratio from 1.1 to 1.8.
A process for the production of a polyolefin fiber suitable for nonwoven fabrics, said process comprising spinning a fiber from an olefin polymer blend in a spinning apparatus with real or equivalent output hole diameter of less than 0.5 mm, and then drawing the resulting fiber out with a draw-ratio of 1.1 to 1.8, said olefin polymer blend comprising (all parts and %s being by weight):
- 1) 50 to 80 parts of a crystalline polymer selected from the group consisting of a propylene homopolymer having an isotactic index greater than 90, and a random copolymer of propylene and an olefin selected from the group consisting of ethylene and C.sub.4 -C.sub.8 .alpha.-olefins, said olefin being 0.05 to 15% of the copolymer;
- and
- 2) 20 to 50 parts of a heterophasic polyolefin composition comprising:
- a) 20 to 70 parts of a propylene polymer of the group consisting of a propylene homopolymer and a random copolymer of propylene and an olefin selected from the group consisting of ethylene and C.sub.4 -C.sub.8 .alpha.-olefins, said olefin being 0.5 to 10% of the copolymer of this group;
- and
- b) 30 to 80 parts of a copolymer of ethylene and an olefin selected from the group consisting of propylene and C.sub.4 -C.sub.8 .alpha.-olefins, said copolymer being soluble in xylene at 25.degree. C., the intrinsic viscosity of said copolymer, when its ethylene content is 40 to 70% of the copolymer, being lower than or equal to 1.5 dl/g, and, when its ethylene content is less than 40% of the copolymer, being lower than or equal to 2.3 dl/g.
Dependencies are inferred from the claim text.