Multi-Layered Fiber

• US 20100190005A1
• Filed: 01/27/2009
• Published: 07/29/2010
• Est. Priority Date: 01/27/2009
• Status: Active Grant

• Current Assignee: Milliken & Company
• Original Assignee: Milliken & Company
• Inventors: Stankovich, Sasha, Nair, Sujith, Wang, Yunzhang, Raghavendran, Venkatkrishna
• Granted Patent: US 7,960,024 B2
• Time in Patent Office: Days
• US Class Current: 428/373
• CPC Class Codes: B32B 2262/0253 Polyolefin fibres
• CPC Class Codes: B32B 2262/0261 Polyamide fibres
• CPC Class Codes: B32B 2262/0269 Aromatic polyamide fibres
• CPC Class Codes: B32B 2262/101 Glass fibres
• CPC Class Codes: B32B 2262/106 Carbon fibres, e.g. graphite fibres
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 5/024 Woven fabric
• CPC Class Codes: B32B 5/026 Knitted fabric
• CPC Class Codes: B32B 5/08 the fibres or filaments of a layer being of different substances , e.g. conjugate fibres, mixture of different fibres
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: B32B 7/027 Thermal properties
• CPC Class Codes: D01F 8/06 with at least one polyolefin as constituent
• CPC Class Codes: D06M 15/227 of hydrocarbons, or reaction products thereof, e.g. afterhalogenated or sulfochlorinated
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2929 Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• CPC Class Codes: Y10T 428/2973 Particular cross section
• CPC Class Codes: Y10T 428/2976 : Longitudinally varying
• CPC Class Codes: Y10T 428/2978 : Surface characteristic

Abstract

A multi-layered fiber including a core, a first layer, and a second layer. The core has an exterior surface portion containing polypropylene. The first layer is disposed on at least a portion of the core and contains a first polymer. The first polymer contains a polymer having at least 70% α-olefin units and is characterized by a melting temperature lower than the melting temperature of the exterior surface portion of the core. The second layer is disposed on at least a portion of the first layer and contains a second polymer. The second polymer contains a co-polymer having at least 50% α-olefin units and is characterized by a number-average molecular weight of about 7,000 g/mol to 50,000 g/mol, a viscosity of between about 2,500 and 150,000 cP measured at 170° C., and a melting temperature lower than the melting temperature of the exterior surface portion of the core. The viscosity of the second polymer is not greater than about 10 percent of the viscosity of the first polymer measured at 170° C. Methods of forming the multi-layered fiber are also disclosed.

Claims

1. A multi-layered fiber comprising:

a core having an exterior surface comprising polypropylene;

a first layer disposed on at least a portion of the core comprising a first polymer, wherein the first polymer comprises a polymer having at least 70% α

-olefin units and is characterized by a melting temperature less than the melting temperature of the exterior surface of the core; and

,

a second layer disposed on at least a portion of the first layer, the second layer comprising a second polymer, wherein the second polymer comprises a co-polymer having at least 50% α

-olefin units and is characterized by a number-average molecular weight of about 7,000 g/mol to 50,000 g/mol, a viscosity of between about 2,500 and 150,000 cP measured at 170°

C., wherein the viscosity of the second polymer is not greater than about 10 percent of the viscosity of the first polymer measured at 170°

C., and a melting temperature lower than the melting temperature of the exterior surface of the core,

wherein the percentage by weight of the second polymer to the total weight of the fiber is between about 0.25% wt and 50% wt.

2. The multi-layered fiber of claim 1, wherein the core comprises fiberglass having an exterior surface of polypropylene.

3. The multi-layered fiber of claim 1, wherein the core comprises a tape fiber.

4. The multi-layered fiber of claim 1, wherein the core has a tensile modulus of greater than 10 grams per denier.

5. The multi-layered fiber of claim 1, wherein the first layer is discontinuous on the core.

6. The multi-layered fiber of claim 1, wherein the melting temperature of the second polymer is lower than the melting temperature of the first polymer.

7. The multi-layered fiber of claim 1, wherein the second polymer has a propylene content of greater than 80% by mole.

8. A method of forming a multi-layered fiber comprising:

providing an elongated core having an exterior surface comprising polypropylene;

applying a first layer to at least a portion of the core, wherein the first layer comprises a first polymer, wherein the first polymer comprises a polymer having at least 70% α

-olefin units and is characterized by a melting temperature less than the melting temperature of the exterior surface of the core;

applying a second layer to at least a portion of the first layer, wherein the second layer comprises a second polymer, wherein the second polymer comprises a co-polymer having at least 50% α

-olefin units and is characterized by a number-average molecular weight of about 7,000 g/mol to 50,000 g/mol, a viscosity of between about 2,500 and 150,000 cP measured at 170°

C., wherein the viscosity of the second polymer is not greater than about 10 percent of the viscosity of the first polymer measured at 170°

C., and a melting temperature lower than the melting temperature of the exterior surface of the core.

9. The method of claim 8, wherein the second polymer has a propylene content of greater than 80% by mole.

10. The method of claim 8, wherein the elongated cores are formed into a fibrous layer before applying the first layer.

11. The method of claim 8, wherein applying the first and second layer to the elongated core comprises the core, first layer, and second layer being formed at the same time in a co-extrusion process.

12. The method of claim 8, wherein the core has a tensile modulus of greater than 20 gram per denier.

13. The method of claim 8, wherein the second layer is discontinuous on the first layer.

14. A method of forming a multi-layered fiber comprising:

providing an elongated core having an exterior surface comprising polypropylene;

applying a first layer to at least a portion of the core, wherein the first layer comprises a first polymer, wherein the first polymer comprises a co-polymer having at least 70% α

-olefin units and is characterized by a viscosity of greater than 1,000,000 cP measured at 170°

C. and a melting temperature less than the melting temperature of the exterior surface of the core;

applying a second layer to at least a portion of the first layer, wherein the second layer comprises a second polymer, wherein the second polymer comprises a co-polymer having at least 80% propylene units and is characterized by a number-average molecular weight of about 7,000 g/mol to 50,000 g/mol, a viscosity of between about 4,000 and 10,000 cP measured at 170°

C., and a melting temperature lower than the melting temperature of the first polymer.

15. The method of claim 14, wherein the elongated cores are formed into a fibrous layer before applying the first or second layer.

16. The method of claim 14, wherein the core of the fiber comprises fiberglass having an exterior surface of polypropylene.

17. The method of claim 14, wherein applying the first and second layer to the elongated core comprises the core, first layer, and second layer being formed at the same time in a co-extrusion process.

18. The method of claim 14, wherein the core has a tensile modulus of greater than 10 grams per denier.

19. The method of claim 14, wherein the second layer is discontinuous on the first layer.