Electroconductive thermoplastic sheet and method of forming same

• US 4,983,452 A
• Filed: 07/19/1988
• Issued: 01/08/1991
• Est. Priority Date: 07/22/1987
• Status: Expired due to Fees

• Current Assignee: Chisso Corporation
• Original Assignee: Chisso Corporation
• Inventors: Daimon, Takashi, Sakamoto, Hideshi
• Primary Examiner(s): Bell, James J.
• Application Number:
  US07/221,365
• Time in Patent Office: 903 Days
• Field of Search: 428/284, 428/286, 428/287, 428/296, 428/300, 428/340, 428/408, 428/922, 428/379, 156/178, 156/148, 156/308.2
• US Class Current: 442/378
• CPC Class Codes: B32B 2255/205 Metallic coating
• CPC Class Codes: B32B 2307/202 Conductive
• CPC Class Codes: B32B 2323/04 Polyethylene
• CPC Class Codes: B32B 2323/10 Polypropylene
• CPC Class Codes: B32B 2325/00 Polymers of vinyl-aromatic compounds, e.g. polystyrene
• CPC Class Codes: B32B 2329/00 Polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals
• CPC Class Codes: B32B 2333/08 Polymers of acrylic acid esters, e.g. PMA, i.e. polymethylacrylate
• CPC Class Codes: B32B 2355/02 ABS polymers, i.e. acrylonitrile-butadiene-styrene polymers
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2377/00 Polyamides
• 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 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/34 comprising polyamides
• CPC Class Codes: B32B 27/365 comprising polycarbonates
• CPC Class Codes: D04H 1/4234 Metal fibres
• CPC Class Codes: D04H 1/4242 Carbon fibres
• CPC Class Codes: D04H 1/4374 : using different kinds of webs, e.g. by layering webs
• CPC Class Codes: D04H 1/43828 : sheath-core
• CPC Class Codes: D04H 1/43835 : Mixed fibres, e.g. at least two chemically different fibres or fibre blends
• CPC Class Codes: D04H 1/58 : by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives in combination with needling D04H1/488
• CPC Class Codes: H01B 1/20 : Conductive material dispersed in non-conductive organic material organic macromolecular compounds or compositions C08
• CPC Class Codes: H01B 1/22 : the conductive material comprising metals or alloys
• CPC Class Codes: H01B 1/24 : the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H05K 9/0079 : Electrostatic discharge protection, e.g. ESD treated surface for rapid dissipation of charges
• CPC Class Codes: Y10S 428/922 : Static electricity metal bleed-off metallic stock
• CPC Class Codes: Y10T 428/27 : Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
• CPC Class Codes: Y10T 428/294 : including metal or compound thereof [excluding glass, ceramic and asbestos]
• CPC Class Codes: Y10T 428/30 : Self-sustaining carbon mass or layer with impregnant or other layer
• CPC Class Codes: Y10T 442/656 : Preformed metallic film or foil or sheet [film or foil or sheet had structural integrity prior to association with the nonwoven fabric]
• CPC Class Codes: Y10T 442/668 : Separate nonwoven fabric layers comprise chemically different strand or fiber material
• CPC Class Codes: Y10T 442/669 : At least one layer of inorganic strand or fiber material and at least one layer of synthetic polymeric strand or fiber material
• CPC Class Codes: Y10T 442/675 : Ester condensation polymer sheet or film [e.g., polyethylene terephthalate, etc.]
• CPC Class Codes: Y10T 442/676 : Vinyl polymer or copolymer sheet or film [e.g., polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, etc.]
• CPC Class Codes: Y10T 442/678 : Olefin polymer or copolymer sheet or film [e.g., polypropylene, polyethylene, ethylene-butylene copolymer, etc.]

Abstract

There is here provided an electroconductive thermoplastic sheet prepared by superposing, upon either surface or both the surface of a thermoplastic film, or sheet an electroconductive nonwoven fabric formed by irregularly twining an electroconductive fiber into a hot-melt adhesive fiber, further superposing, upon the outer side of the electroconductive nonwoven fabric, a nonwoven fabric made from the hot-melt adhesive fiber to obtain a laminate, and fusing the laminate integrally.

The sheet of the present invention retains transparency and electroconductivity, and it is suitable for, for example, materials for packing of electronic parts and precision instruments where dust deposition and static electricity obstruction should be avoided.

Claims

1. An electroconductive thermoplastic integrally laminated sheet comprising:

(a) a thermoplastic sheet;

(b) an electroconductive nonwoven fabric formed from electroconductive fibers irregularly intertwined with hot-melt adhesive fibers, said electroconductive nonwoven fabric being superposed on at least one surface of said thermoplastic sheet; and

(c) a nonwoven fabric formed from said hot-melt adhesive fibers superposed upon the outer surface of said electroconductive nonwoven fabric.

2. An electroconductive thermoplastic sheet according to claim 1 wherein the weight of the nonwoven fabric formed from the hot-melt adhesive fiber is in the range of 5 to 30 g/m².

3. An electroconductive thermoplastic sheet according to claim 1 wherein the thermoplastic resin for the thermoplastic film or sheet is at least resin one two or more selected from the group consisting of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polystyrene, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, polymethyl acrylate, 6-nylon, 6,6-nylon, 12-nylon and 6,12-nylon, polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, polycarbonates and polyphenylene oxide.

4. An electroconductive thermoplastic sheet according to claim 1 wherein the hot-melt adhesive fiber used in the electroconductive nonwoven fabric and the nonwoven fabric made from the hot-melt adhesive fiber is prepared by subjecting, to post-treatments of melting, spinning, stretching, crimping and cutting, at least one material selected from the group consisting of propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer, propylene-ethylene-butene-1 block copolymer, propylene-ethylene-butene-1 random copolymer and propylene-butene-1 random copolymer containing at least 70% by weight of a propylene component, modified polypropylenes prepared by modifying the above-mentioned copolymers with an unsaturated carboxylic acid or its anhydride, polyethylene, polyacrylonitrile, polyamide, polyvinyl chloride, polyethylene terephthalate or polybutylene terephthalate.

5. An electroconductive thermoplastic sheet according to claim 1 wherein the electroconductive fiber is at least one selected from the group consisting of metallic compound-coated synthetic fibers prepared by coating synthetic fibers with metallic compounds such as copper sulfide, copper iodide, stannous oxide and indium oxide;

metal-plated synthetic fibers prepared by plating synthetic fibers with nickel, copper and the like;

carbon-coated synthetic fibers prepared by coating synthetic fibers with electroconductive resins containing carbon particles;

metal-plated glass fibers prepared by plating glass fibers with metals such as nickel, copper and the like;

carbon fibers;

metal-plated carbon fibers prepared by plating carbon fibers with nickel and the like; and

metallic fibers prepared by converting aluminum, copper, stainless steel and the like into a fibrous form.

6. An electroconductive thermoplastic sheet according to claim 1 wherein the electroconductive nonwoven fabric and the nonwoven fabric formed from hot-melt adhesive fiber are prepared by a method of a binder process, a thermal fusion process, a wet manufacturing process or a needle punching process.

7. An electroconductive thermoplastic sheet according to claim 1 wherein the weight of the electroconductive nonwoven fabric is 30 g/m² or less.

8. An electroconductive thermoplastic sheet according to claim 1 wherein the concentration of the electroconductive fiber in a fibrous mixture for the electroconductive nonwoven fabric is in the range of 1 to 99% by weight.

9. An electroconductive thermoplastic sheet according to claim 1 wherein the concentration of the electroconductive fiber in a fibrous mixture for the electroconductive nonwoven fabric is in the range of 3 to 60% by weight.

10. A process for forming an electroconductive thermoplastic sheet comprising:

irregularly intertwining electroconductive fibers with hot-melt adhesive fibers to form an electroconductive nonwoven fabric;

superposing said electroconductive nonwoven fabric upon at least one surface of a thermoplastic sheet;

superposing a nonwoven fabric formed from said hot-melt adhesive fibers on the outer surface of said electroconductive nonwoven fabric to form a laminate; and

fusing said laminate.

11. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the weight of the nonwoven fabric formed from the hot-melt adhesive fiber is in the range of 5 to 30 g/m².

12. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the thermoplastic resin for the thermoplastic film or sheet is at least one resin selected from the group consisting of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polystyrene, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, polymethyl acrylate, 6-nylon, 6,6-nylon, 12-nylon and 6,12-nylon, polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, polycarbonates and polyphenylene oxide.

13. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the hot-melt adhesive fiber used in the electroconductive nonwoven fabric and the nonwoven fabric made from the hot-melt adhesive fiber is prepared by subjecting, to post-treatments of melting, spinning, stretching, crimping and cutting, at least one material selected from the group consisting of propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer, propylene-ethylene-butene-1 block copolymer, propylene-ethylene-butene-1 random copolymer and propylene-butene-1 random copolymer containing at least 70% by weight of a propylene component, modified polypropylenes prepared by modifying the above-mentioned copolymers with an unsaturated carboxylic acid or its anhydride, polyethylene, polyacrylonitrile, polyamide, polyvinyl chloride, polyethylene terephthalate or polybutylene terephthalate.

14. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the electroconductive fiber is at least one selected from the group consisting of metallic compound-coated synthetic fibers prepared by coating synthetic fibers with metallic compounds such as copper sulfide, copper iodide, stannous oxide and indium oxide;

metal-plated synthetic fibers prepared by plating synthetic fibers with nickel, copper and the like;

carbon-coated synthetic fibers prepared by coating synthetic fibers with electroconductive resins containing carbon particles;

metal-plated glass fibers prepared by plating glass fibers with metals such as nickel, copper and the like;

carbon fibers;

metal-plated carbon fibers prepared by plating carbon fibers with nickel and the like; and

metallic fibers prepared by converting aluminum, copper, stainless steel and the like into a fibrous form.

15. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the electroconductive nonwoven fabric and the nonwoven fabric formed from hot-melt adhesive fiber are prepared by a method of a binder process, a thermal fusion process, a wet manufacturing process or a needle punching process.

16. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the weight of the electronconductive nonwoven fabric is 30 g/m² or less.

17. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the concentration of the electroconductive fiber in a fibrous mixture for the electroconductive nonwoven fabric is in the range of 1 to 99% by weight.

18. The process for forming an electroconductive thermoplastic sheet according to claim 10 wherein the concentration of the electroconductive fiber in a fibrous mixture for the electroconductive nonwoven fabric is in the range of 3 to 60% by weight.