Low creep fiber
The invention relates to a process for the preparation of a gel spun UHMWPE fiber comprising the steps of providing an ultra high molecular weight polyethylene composition having an intrinsic viscosity (IV) of at least 8 dl/g, a co-monomer content (CBR) of a least 0.05 SCB/1000TC, a mass averaged distribution of the co-monomer (CMAD) of at least 0.05, wherein the co-monomer has at least 4 carbon atoms, dissolving the composition in a solvent to form a polymer solution having a UHMWPE concentration of between 2 and 40 wt %, spinning the polymer solution through a multi orifice die plate to form a solution fibers, cooling the solution fiber to below 80° C. to form a gel fiber, drawing the fiber in at least one step to form a drawn fiber, removing at least a portion of the solvent before, during or after the drawing, wherein the ratio CMAD to CBR is greater than 1.0. The invention further relates to a gel-spun UHMWPE fiber obtainable by the process and products comprising said gel-spun UHMWPE fiber.
1. A process for the preparation of a gel spun ultrahigh molecular weight polyethylene (UHMWPE) fiber comprising the steps of:
(a) providing an ultra high molecular weight polyethylene (UHMWPE) composition having an intrinsic viscosity (IV) of at least 8 dl/g, a co-monomer content (C BR ) of a least 0.05 SCB/1000TC, and a mass averaged distribution of the co-monomer (C MAD ) of at least 0.05, wherein the co-monomer has at least 4 carbon atoms and a ratio of C MAD to C BR is greater than 1.0,
(b) dissolving the composition in a solvent to form a polymer solution having a UHMWPE concentration of between 2 and 40 wt %,
(c) spinning the polymer solution through a multi orifice die plate to form a solution fiber,
(d) cooling the solution fiber to below 80° C. to form a gel fiber,
(e) drawing the gel fiber in at least one step to form a drawn fiber, and
(f) removing at least a portion of the solvent before, during or after the drawing.
2. The process of claim 1 , wherein the ratio of C MAD to C BR is greater than 1.05.
3. The process according to claim 1 , wherein the UHMWPE composition comprises at least 2 different UHMWPE polymers A and B.
4. The process according to claim 3 , wherein
the UHMWPE polymer A has an IV of 8-40 dl/g, and a C BR of less than 0.1 SCB/1000TC, and/or
the UHMWPE polymer B has an IV of 8-40 dl/g, and a C BR from 0.1 to 5.0 SCB/1000TC.
5. The process according to claim 3 , wherein a ratio of the IV of the polymer A to the IV of the polymer B is less than 1.
6. The process according to claim 3 , wherein the polymer A and the polymer B are present in a weight ratio of the polymer A to the polymer B which is between 0.02 and 50.
7. The process according to claim 3 , wherein the polymer A is a Ziegler catalyzed polymer and the polymer B is a molecular catalyst polymer.
8. The process according to claim 1 , wherein the co-monomer is one or more monomers selected from the group consisting of alpha-olefins with at least 4 carbon atoms, cyclic olefins having 5 to 20 carbon atoms and linear, branched or cyclic dienes having 4 to 20 carbon atoms.
9. The process according to claim 1 , wherein the co-monomer is one or more monomers selected from the group consisting of 1-butene, 1-pentene, 1-hexene and 1-octene.
10. The process of claim 1 , wherein the ratio of C MAD to C BR is greater than 1.1.
11. The process according to claim 5 , wherein the ratio of the IV of the polymer A to the IV of the polymer B is at most 0.9.
12. The process according to claim 5 , wherein the ratio of the IV of the polymer A to the IV of the polymer B is at most 0.8.
13. The process according to claim 6 , wherein the weight ratio of polymer A to polymer B is between 0.1 and 10.
14. The process according to claim 6 , whereby the weight ratio of polymer A to polymer B is between 0.25 and 4.
15. The process according to claim 9 , wherein the comonomer is selected form the group consisting of 1-butene and 1-hexene to provide ethyl or butyl branches to the UHMWPE polymer B.
16. A gel spun UHMWPE fiber obtained by the process of claim 1 .
17. The gel spun UHMWPE fiber of claim 16 , wherein C MAD to C BR is greater than 1.2.
18. The gel spun UHMWPE fiber of claim 16 , wherein the fiber has a tenacity of at least 25 cN/dtex.
19. The gel spun fiber of claim 16 , wherein the fiber has a tenacity of at least 32 cN/dtex.
20. The gel spun fiber of claim 16 , wherein the fiber has a tenacity of at least 38 cN/dtex.
21. A product comprising the gel spun fiber according to claim 18 , wherein the product is selected from the group consisting of chains, medical devices, laminates and composite articles.
22. A product comprising the gel spun fiber according to claim 16 , wherein the product is selected from the group consisting of yarns, ropes, cables, nets, fabrics, and protective appliances.
23. The product according to claim 22 , wherein the product is a ballistic resistant article.
24. A product comprising the gel spun fiber according to claim 16 , wherein the product is selected from the group consisting of chains, medical devices, laminates and composite articles.
25. A gel spun ultrahigh molecular weight polyethylene (UHMWPE) fiber comprising:
an intrinsic viscosity (IV) of at least 4 dl/g,
a co-monomer content (C BR ) of a least 0.05 SCB/1000TC, and
a mass averaged distribution of the co-monomer (C MAD ) of at least 0.05, wherein
a ratio of C MAD to C BR is greater than 1.
26. The gel spun UHMWPE fiber of claim 25 , wherein the C MAD to C BR is greater than 1.05.
27. The gel spun UHMWPE fiber of claim 25 , wherein the C MAD to C BR is greater than 1.1.
28. A product comprising the gel spun fiber according to claim 25 , wherein the product is selected from the group consisting of yarns, ropes, cables, nets, fabrics, and protective appliances.
29. The product according to claim 28 , wherein the product is a ballistic resistant article.
30. A product comprising the gel spun fiber according to claim 25 , wherein the product is selected from the group consisting of chains, medical devices, laminates and composite articles.