Continuous fiber reinforced thermoplastic rod and pultrusion method for its manufacture

Patent metadata

Field	Value
Publication number	US-10676845-B2
Application number	US-201214005832-A
Country	US
Kind code	B2
Filing date	Apr 11, 2012
Priority date	Apr 12, 2011
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

A composite rod for use in various applications, such as electrical cables (e.g., high voltage transmission cables), power umbilicals, tethers, ropes, and a wide variety of other structural members, is provided. The rod includes a core that is formed from a plurality of unidirectionally aligned fiber rovings embedded within a thermoplastic polymer matrix. The present inventors have discovered that the degree to which the rovings are impregnated with the thermoplastic polymer matrix can be significantly improved through selective control over the impregnation process, and also through control over the degree of compression imparted to the rovings during formation and shaping of the rod, as well as the calibration of the final rod geometry. Such a well impregnated rod has a very small void fraction, which leads to excellent strength properties. Notably, the desired strength properties may be achieved without the need for different fiber types in the rod.

First claim

What is claimed is:

1. A composite rod extending in a longitudinal direction, wherein the rod contains a core comprising a plurality of thermoplastic impregnated rovings, the rovings containing continuous fibers oriented in the longitudinal direction and a thermoplastic matrix that embeds the fibers, the fibers having a ratio of ultimate tensile strength to mass per unit length of greater than 1,000 Megapascals per gram per meter, wherein the continuous fibers constitute from 25 wt. % to 80 wt % of the core and the thermoplastic matrix constitutes from 20 wt. % to 75 wt. % of the core, and wherein the rovings are distributed generally symmetrically about a longitudinal center of the core, wherein the core has a void fraction of 3% or less, and wherein the rod has a minimum flexural modulus of 10 Gigapascals, a bend radius of less than 40 times the outer diameter of the rod, and a minimum ultimate tensile strength of 300 Megapascals.

2. The composite rod of claim 1 , wherein the continuous fibers have a ratio of ultimate tensile strength to mass per unit length of from about 5,500 to about 20,000 Megapascals per gram per meter.

3. The composite rod of claim 1 , wherein the continuous fibers are carbon fibers.

4. The composite rod of claim 1 , wherein the thermoplastic matrix includes a polyarylene sulfide.

5. The composite rod of claim 4 , wherein the polyarylene sulfide is polyphenylene sulfide.

6. The composite rod of claim 1 , wherein the continuous fibers constitute from about 30 wt. % to about 75 wt. % of the core.

7. The composite rod of claim 1 , wherein the rod has a minimum tensile modulus of elasticity of about 50 Gigapascals.

8. The composite rod of claim 1 , wherein the rod has a bend radius of from about 0.5 to about 10 centimeters.

9. The composite rod of claim 1 , wherein the core contains from 4 to 20 rovings.

10. The composite rod of claim 1 , wherein each roving contains from about 1,000 to about 50,000 individual continuous fibers.

11. The composite rod of claim 1 , wherein the rod has a thickness of from about 0.1 to about 50 millimeters.

12. The composite rod of claim 1 , further comprising a capping layer that surrounds the core.

13. The composite rod of claim 1 , wherein the rod has a substantially circular cross-sectional shape.

14. A method for forming a composite rod extending in a longitudinal direction, wherein the method comprises:
impregnating a plurality of rovings with a thermoplastic matrix and consolidating the rovings to form a ribbon, wherein the rovings comprise continuous fibers oriented in the longitudinal direction, said fibers having a ratio of ultimate tensile strength to mass per unit length of greater than about 1,000 Megapascals per gram per meter, wherein the continuous fibers constitute from about 25 wt. % to about 80 wt. % of the ribbon and the thermoplastic matrix constitutes from about 2 wt. % to about 75 wt. % of the ribbon, wherein the ribbon has a void fraction of about 3% or less;
heating the ribbon;
pulling the heated ribbon through at least one forming die to compress and shape the ribbon into a preform; and
cooling the preform to form the rod, wherein the rod has a minimum flexural modulus of about 10 Gigapascals, a bend radius of less than 40 times the outer diameter of the rod, and a minimum ultimate tensile strength of 300 Megapascals.

15. The method of claim 14 , wherein the continuous fibers are carbon fibers.

16. The method of claim 14 , wherein the thermoplastic matrix includes a polyarylene sulfide.

17. The method of claim 14 , wherein the continuous fibers constitute from about 30 wt. % to about 75 wt. % of the ribbon.

18. The method of claim 14 , wherein the ribbon has a void traction of about 2% or less.

19. The method of claim 14 , wherein from 1 to 15 individual ribbons are employed.

20. The method of claim 14 , wherein the ribbons are heated within an infrared oven.

21. The method of claim 14 , wherein the rovings are spaced substantially equidistant from each other in the ribbon.

22. The method of claim 14 , wherein the rovings are impregnated within an extrusion device.

23. The method of claim 14 , wherein the rovings traverse through the device in a tortuous pathway.

24. The method of claim 14 , wherein a manifold assembly supplies the thermoplastic matrix to the extrusion device, the manifold assembly comprising branched runners through which the thermoplastic matrix flows.

25. The method of claim 14 , wherein the rovings are under tension when impregnated with the thermoplastic matrix.

26. The method of claim 14 , wherein the heated ribbon is pulled through a consolidation die and a subsequent calibration die to compress the ribbon.

27. The method of claim 14 , wherein the preform is allowed to cool after exiting the consolidation die and before entering the calibration die.

28. A composite rod extending in a longitudinal direction, wherein the rod contains a core comprising a plurality of thermoplastic impregnated rovings, the rovings containing continuous fibers oriented in the longitudinal direction and a thermoplastic matrix that embeds the fibers, the fibers having a ratio of ultimate tensile strength to mass per unit length of greater than about 1,000 Megapascals per gram per meter, wherein the continuous fibers constitute from about 25 wt. % to about 80 wt % of the core and the thermoplastic matrix constitutes from about 20 wt. % to about 75 wt. % of the core, wherein the core has a void fraction of 3% or less, and wherein the rod has a minimum flexural modulus of about 10 Gigapascals, a bend radius of less than 40 times the outer diameter of the rod, and a minimum ultimate tensile strength of 300 Megapascals.

29. The composite rod of claim 28 , wherein the continuous fibers are carbon fibers.

30. The composite rod of claim 28 , wherein the thermoplastic matrix includes a polyarylene sulfide.

31. The composite rod of claim 30 , wherein the polyarylene sulfide is polyphenylene sulfide.

32. The composite rod of claim 28 , wherein the rod has a minimum tensile modulus of elasticity of about 50 Gigapascals.

33. The composite rod of claim 28 , wherein the rod has a bend radius of from about 0.5 to about 10 centimeters.

34. The composite rod of claim 28 , wherein the rod has a thickness of from about 0.1 to about 50 millimeters.

35. The composite rod of claim 28 , further comprising a capping layer that surrounds the core.

Assignees

• Nelson Sherri M
• Eastep David W
• Tibor Timothy L
• Regan Timothy A
• Wesley Michael L
• Stiehm Richard
• Ticona Llc

Inventors

• Nelson Sherri M
• Eastep David W
• Tibor Timothy L
• Regan Timothy A
• Wesley Michael L
• Stiehm Richard

Classifications

• B29B15/122

  with a matrix in liquid form, e.g. as melt, solution or latex · CPC title

• Y10T428/2918

  including free carbon or carbide or therewith [not as steel] · CPC title

• D01F8/04

  from synthetic polymers · CPC title

• Y10T428/2931

  Fibers or filaments nonconcentric [e.g., side-by-side or eccentric, etc.] · CPC title

• D01F8/18 Primary

  from other substances · CPC title