Heat recoverable article comprising conductive polymer compositions

• US 5,030,487 A
• Filed: 11/13/1989
• Issued: 07/09/1991
• Est. Priority Date: 04/04/1984
• Status: Expired due to Fees

• Current Assignee: Central Plastics Co. (Georg Fischer AG)
• Original Assignee: Raychem Corporation (TE Connectivity Limited)
• Inventors: Rosenzweig, Nachum
• Primary Examiner(s): Seidleck, James J.
• Application Number:
  US07/435,854
• Time in Patent Office: 603 Days
• Field of Search: 428/34.9, 428/35.1, 428/327, 174/DIG. 8, 285/381
• US Class Current: 428/34.9
• CPC Class Codes: B29C 2035/0211 resistance heating B29C2035/0811 takes precedence
• CPC Class Codes: B29C 2035/0811 using induction
• CPC Class Codes: B29C 2035/0855 using microwave
• CPC Class Codes: B29C 61/003 characterised by the choice of material
• CPC Class Codes: B29C 61/0625 Preforms comprising incorporated or associated heating means
• CPC Class Codes: B29C 65/68 using auxiliary shrinkable elements
• CPC Class Codes: B29C 66/112 Single lapped joints
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/114 Single butt joints
• CPC Class Codes: B29C 66/118 Single monotone curved joints
• CPC Class Codes: B29C 66/1222 comprising at least a lapped joint-segment
• CPC Class Codes: B29C 66/1224 comprising at least a butt joint-segment
• CPC Class Codes: B29C 66/5221 for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
• CPC Class Codes: B29C 66/52241 with two right angles, e.g. for making T-shaped pieces
• CPC Class Codes: B29C 66/5229 involving the use of a socket
• CPC Class Codes: B29C 66/52291 said socket comprising a stop
• CPC Class Codes: B29C 66/52293 said stop being external
• CPC Class Codes: B29C 66/52298 said socket being composed by several elements
• CPC Class Codes: B29C 66/5326 said single elements being substantially flat
• CPC Class Codes: B29C 66/636 using a support which remains in the joined object
• CPC Class Codes: B29C 66/71 : characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/723 : being multi-layered B29C66/7292, B29C66/72941 take precedence
• CPC Class Codes: B29C 66/735 : characterised by the extensive physical properties of the parts to be joined
• CPC Class Codes: B29C 66/73921 : characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/73941 : characterised by the materials of both parts being thermosets
• CPC Class Codes: B29C 73/10 : using patches sealing on the surface of the article B29C73/14 takes precedence
• CPC Class Codes: B29C 73/34 : for local heating
• CPC Class Codes: B29K 2023/00 : Use of polyalkenes or derivatives thereof as moulding material
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/0675 : HMWPE, i.e. high molecular weight polyethylene
• CPC Class Codes: B29K 2023/0683 : UHMWPE, i.e. ultra high molecular weight polyethylene
• CPC Class Codes: B29K 2023/0691 : PEX, i.e. crosslinked polyethylene
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2027/06 : PVC, i.e. polyvinylchloride
• CPC Class Codes: B29K 2033/08 : Polymers of acrylic acid esters, e.g. PMA, i.e. polymethylacrylate
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2069/00 : Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2079/08 : PI, i.e. polyimides or derivatives thereof
• CPC Class Codes: B29K 2707/04 : Carbon
• CPC Class Codes: B29K 2995/0005 : Conductive
• CPC Class Codes: B29K 2995/0088 : Molecular weight
• CPC Class Codes: F16L 47/22 : using shrink-down material
• CPC Class Codes: F16L 55/17 : by means of rings, bands or sleeves pressed against the outside surface of the pipe or hose
• CPC Class Codes: Y10S 174/08 : Shrinkable tubes
• CPC Class Codes: Y10T 428/1328 : Shrinkable or shrunk [e.g., due to heat, solvent, volatile agent, restraint removal, etc.]
• CPC Class Codes: Y10T 428/1331 : Single layer [continuous layer]
• CPC Class Codes: Y10T 428/254 : Polymeric or resinous material

Abstract

A method of joining, repairing or reinforcing substrates, particularly polymeric pipes for transporting fluids, e.g. natural gas and water. The method makes use of an article, preferably a heat-recoverable article, which comprises a conductive polymer composition and which is heated to its recovery temperature by passing electrical current through the conductive polymer. Preferably the article is a heat-shrinkable coupler. The coupler may make direct contact with and fuse to the pipes, or there may be an insert between the coupler and the pipes. The article preferably comprises carbon blank dispersed in either a sintered polymer, particularly ultra high molecular weight polyethylene or a very high molecular weight polymer, particularly polyethylene having a molecular weight greater than 150,000.

Claims

1. A heat-recoverable article comprising a heat-recoverable element which is composed of a conductive polymer composition comprising

(a) a matrix consisting essentially of organic polymer particles which have been sintered together so that the particles have coalesced without losing their identity, and

(b) a particulate conductive filler which is dispersed in said matrix but is present substantially only at or near the boundaries of the coalesced particles.

2. An article according to claim 1 wherein the matrix consists essentially of ultra high molecular weight polyethylene.

3. An article according to claim 2 wherein the particulate conductive filler comprises carbon black.

4. An article according to claim 1 comprising an insert arranged to be located, in use, between the article and a substrate.

5. An article according to claim 2 wherein the polyethylene has a molecular weight greater than about 1.5 million.

6. An article according to claim 5 wherein the polyethylene has a molecular weight greater than about 3.0 million.

7. An article according to claim 3 wherein the carbon black is present in an amount less than 9% by volume of the composition.

8. An article according to claim 7 wherein the carbon black is present in an amount 2 to 6% by volume of the composition.

9. An article according to claim 3 wherein the conductive polymer composition has resistivity at 23°

C. of 1.5 to 100 ohm.cm.

10. An article according to claim 9 wherein the conductive polymer composition has a resistivity of 2.5 to 25 ohm.cm.

11. An article according to claim 4 wherein the insert comprises a self-supporting layer.

12. An article according to claim 4 wherein the insert comprises an adhesive layer.

13. An article according to claim 4 wherein the insert comprises a thermosetting resin layer.

14. An article according to claim 1 wherein the article is a radially shrinkable tube of cylindrical cross-section.

15. An article according to claim 14 wherein the tube comprises two parts.

16. An article according to claim 14 wherein the tube has a ratio of radial diameter to wall thickness of less than 18:

1 after the article has been recovered.

17. An article according to claim 16 wherein the tube has a ratio of 2:

1 to 12;

1 after recovery.

18. An article according to claim 14 wherein the tube has a wall thickness of at least 0.07 inch.

19. An article according to claim 1 wherein the article is a coupler for joining at least two pipes.

20. An article according to claim 1 wherein the conductive polymer composition is crosslinked.

21. An article according to claim 20 wherein the composition is crosslinked by irradiation to 3 to 20 Mrad.