Composite thermoplastic sheets including natural fibers

• US 20060099393A1
• Filed: 11/08/2004
• Published: 05/11/2006
• Est. Priority Date: 11/08/2004
• Status: Active Grant

• Current Assignee: Hanwa Azdel, Inc.
• Original Assignee: AZDEL Incorporated (Hanwha Corporation)
• Inventors: Raghavendran, Venkat Krishna, Woodman, Daniel Scott, McHugh, John Joseph
• Granted Patent: US 7,431,980 B2
• Time in Patent Office: Days
• US Class Current: 428/292.1
• CPC Class Codes: B29C 70/30 Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
• CPC Class Codes: B32B 2262/065 Lignocellulosic fibres, e.g. jute, sisal, hemp, flax, bamboo
• CPC Class Codes: B32B 2262/10 Inorganic fibres layered products comprising a layer of natural mineral fibres B32B19/00
• CPC Class Codes: B32B 2266/0292 Thermoplastic elastomer
• CPC Class Codes: B32B 2266/06 Open cell foam
• CPC Class Codes: B32B 2307/716 Degradable
• CPC Class Codes: B32B 2307/718 Weight, e.g. weight per square meter
• CPC Class Codes: B32B 2419/00 Buildings or parts thereof walls, panels B32B2607/00
• CPC Class Codes: B32B 2605/003 Interior finishings
• CPC Class Codes: B32B 5/18 characterised by features of a layer of foamed material
• CPC Class Codes: B32B 5/32 at least two layers being foamed and next to each other
• CPC Class Codes: B32B 9/02 comprising animal or vegetable substances , e.g. cork, bamboo, starch
• CPC Class Codes: D04H 1/425 Cellulose series
• CPC Class Codes: D04H 1/4266 Natural fibres not provided for in group D04H1/425
• CPC Class Codes: D04H 1/60 the bonding agent being applied in dry state, e.g. thermo-activatable agents in solid or molten state, and heat being applied subsequently
• CPC Class Codes: D21H 11/12 Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• CPC Class Codes: D21H 13/26 Polyamides; Polyimides
• CPC Class Codes: D21H 17/34 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: Y10T 428/249924 Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity
• CPC Class Codes: Y10T 428/24994 Fiber embedded in or on the surface of a polymeric matrix
• CPC Class Codes: Y10T 428/24995 : Two or more layers
• CPC Class Codes: Y10T 428/249986 : Void-containing component contains also a solid fiber or solid particle

Abstract

A composite sheet material includes, in an exemplary embodiment a porous core that includes at least one thermoplastic material and from about 20 weight percent to about 80 weight percent of natural fibers based on a total weight of the porous core. The natural fibers include at least one of kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulosic fibers, sisal fibers, and coir fibers.

Claims

1. A composite sheet material comprising:

a permeable core comprising discontinuous natural fibers bonded together with a thermoplastic resin, said permeable core having a density from about 0.1 gm/cc to about 1.8 gm/cc, said permeable core including a surface region

2. A composite sheet in accordance with claim 1 wherein said natural fibers comprise at least one of kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulosic fibers, sisal fibers, and coir fibers.

3. A composite sheet material in accordance with claim 1 wherein said permeable core has an open cell structure with a void content of about 1 percent to about 95 percent of the total volume of said permeable core.

4. A composite sheet material in accordance with claim 1 wherein said permeable core comprises a thermoplastic resin selected from the group consisting of polyolefins, polystyrene, acrylonitrylstyrene, butadiene, polyesters, polybutyleneterachlorate, polyvinyl chloride, polyphenylene ether, polycarbonates, polyestercarbonates, acrylonitrile-butylacrylate-styrene polymers, amorphous nylon, and mixtures thereof.

5. A composite sheet material in accordance with claim 1 wherein said core comprises from about 20 to about 80 percent by weight of said natural fibers and from about 20 to about 80 percent by weight of said thermoplastic resin.

6. A composite sheet material in accordance with claim 1 wherein said core comprises from about 35 to about 55 percent by weight of said natural fibers and from about 45 to about 65 percent by weight of said thermoplastic resin.

7. A composite sheet material in accordance with claim 1 having a thickness from about 0.5 mm to about 50 mm.

8. A composite sheet material in accordance with claim 1 further comprising an adherent layer adjacent to said surface region.

9. A composite sheet material according to claim 8 wherein said adherent layer has a thickness from about 25 micrometers to about 2.5 mm.

10. A composite sheet material according to claim 8 wherein said adherent adjacent layer comprises at least one of a thermoplastic film, an elastomeric film, a metal foil, a thermosetting coating, an inorganic coating, a fiber based scrim, a non-woven fabric, and a woven fabric.

11. A composite sheet material in accordance with claim 2 wherein said permeable core further comprises at least one of metal fibers, metalized inorganic fibers, metalized synthetic fibers, glass fibers, graphite fibers, carbon fibers, ceramic fibers, basalt fibers, inorganic fibers, and aramid fibers.

12. A composite sheet material comprising:

a porous core comprising at least one thermoplastic material and from about 20 weight percent to about 80 weight percent of natural fibers based on a total weight of said porous core layer, said natural fibers comprising at least one of kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulosic fibers, sisal fibers, and coir fibers.

13. A composite sheet material in accordance with claim 12 wherein said porous core has an open cell structure with a void content of about 1 percent to about 95 percent of the total volume of said porous core.

14. A composite sheet material in accordance with claim 12 wherein said porous core comprises a thermoplastic resin selected from the group consisting of polyolefins, polystyrene, acrylonitrylstyrene, butadiene, polyesters, polybutyleneterachlorate, polyvinyl chloride, polyphenylene ether, polycarbonates, polyestercarbonates, acrylonitrile-butylacrylate-styrene polymers, amorphous nylon, and mixtures thereof.

15. A composite sheet material in accordance with claim 12 wherein said porous core comprises from about 35 to about 55 percent by weight of said natural fibers and from about 45 to about 65 percent by weight of said thermoplastic resin.

16. A composite sheet material in accordance with claim 12 having a thickness from about 0.5 mm to about 50 mm.

17. A composite sheet material in accordance with claim 12 further comprising at least one skin, each said skin covering at least a portion of a surface of said porous core layer, said skin comprising at least one of a thermoplastic film, an elastomeric film, a metal foil, a thermosetting coating, an inorganic coating, a fiber based scrim, a non-woven fabric, and a woven fabric.

18. A composite sheet material in accordance with claim 12 wherein said porous core further comprises at least one of metal fibers, metalized inorganic fibers, metalized synthetic fibers, glass fibers, graphite fibers, carbon fibers, ceramic fibers, basalt fibers, inorganic fibers, and aramid fibers.

19. A method of fabricating a porous, natural fiber-reinforced thermoplastic sheet, said method comprising:

adding natural fibers having an average length of about 5 mm to about 50 mm, and thermoplastic resin powder particles to an agitated aqueous foam to form a dispersed mixture;

laying the dispersed mixture of natural fibers and thermoplastic resin particles down onto a wire mesh;

evacuating the water to form a web;

heating the web above the glass transition temperature of the thermoplastic resin; and

pressing the web to a predetermined thickness to form a porous thermoplastic composite sheet having a void content of about 1 percent to about 95 percent.

20. A method in accordance with claim 19 wherein the natural fibers comprise at least one of kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulosic fibers, sisal fibers, and coir fibers.

21. A method in accordance with claim 19 wherein the thermoplastic resin comprises at least one of polyolefins, polystyrene, acrylonitrylstyrene, butadiene, polyesters, polybutyleneterachlorate, polyvinyl chloride, polyphenylene ether, polycarbonates, polyestercarbonates, acrylonitrile-butylacrylate-styrene polymers, amorphous nylon, and mixtures thereof.

22. A method in accordance with claim 19 wherein the porous thermoplastic composite sheet comprises from about 20 to about 80 percent by weight of the natural fibers and from about 20 to about 80 percent by weight of the thermoplastic resin.

23. A method in accordance with claim 19 wherein the porous thermoplastic composite sheet comprises from about 35 to about 55 percent by weight of the natural fibers and from about 45 to about 65 percent by weight of the thermoplastic resin.

24. A method in accordance with claim 19 further comprising adhering a skin to at least a portion of a surface of the porous thermoplastic composite sheet.

25. A method in accordance with claim 24 wherein the skin comprises at least one of a thermoplastic film, an elastomeric film, a metal foil, a thermosetting coating, an inorganic coating, a fiber based scrim, a non-woven fabric, and a woven fabric.

26. A method in accordance with claim 19 further comprises adding at least one of metal fibers, metalized inorganic fibers, metalized synthetic fibers, glass fibers, graphite fibers, carbon fibers, ceramic fibers, and aramid fibers to the agitated aqueous foam.