Polyethylene materials

Patent metadata

Field	Value
Publication number	US-9745462-B2
Application number	US-62155209-A
Country	US
Kind code	B2
Filing date	Nov 19, 2009
Priority date	Nov 20, 2008
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

Certain embodiments described herein are directed to polymer compositions including a base material, a secondary material and an antioxidant. The composition also includes crystalline regions and amorphous regions with the crystalline regions comprising at least 62% by volume of the composition. In some embodiments, the base material is an ultra high molecular weight polyethylene material and the secondary material is a polyethylene material that is different than the base material.

First claim

What is claimed is:

1. A composition comprising:
one or more crystalline and one or more amorphous regions, the crystalline regions together comprising at least 62% by volume of the composition, the crystalline and amorphous regions together comprising an about 50 kGy to about 200 kGy electron beam irradiation cross-linked form of a blend comprising
a first ultra high molecular weight polyethylene that is about 80 wt % to about 90 wt % of the irradiation cross-linked form of the blend and a cross-linked polymeric material that is about 10 wt % to about 20 wt % of the irradiation cross-linked form of the blend, the cross-linked polymeric material comprising an about 50 kGy to about 200 kGy electron beam irradiation cross-linked form of a blend of a second antioxidant that is vitamin E and a second ultra high molecular weight polyethylene material, wherein the second antioxidant is about 0.1 wt % to about 0.2 wt % of the cross-linked polymeric material and the second ultra high molecular weight polyethylene material is the remainder thereof, and the cross-linked polymeric material is free of melting after the cross-linking of the blend comprising the second antioxidant and the second ultra high molecular weight polyethylene material; and
a first antioxidant that is vitamin E and that is about 0.2 wt % to about 0.5 wt % of the irradiation cross-linked form of the blend, at least some of the first antioxidant present in the blend of the first ultra high molecular weight polyethylene material and the cross-linked polymeric material prior to the irradiation;

wherein the second ultra high molecular weight polyethylene material has a different average molecular weight than the first ultra high molecular weight polyethylene material, and wherein the irradiation cross-linked form of the blend is free of melting after the cross-linking of the blend comprising the first ultra high molecular weight polyethylene, the cross-linked polymeric material, and the first antioxidant.

2. The composition of claim 1 , wherein the cross-linked form of the first ultra high molecular weight polyethylene material and the cross-linked polymeric material are each present in an amount effective to provide at least a bimodal molecular weight distribution in the composition.

3. The composition of claim 1 , wherein the one or more crystalline and amorphous regions comprise one or more first crystalline regions from the cross-linked form of the first ultra high molecular weight polyethylene material and one or more second, different crystalline regions from the cross-linked polymeric material.

4. The composition of claim 3 , wherein the one or more second, different crystalline regions have a substantially homogenous distribution throughout the one or more first crystalline regions.

5. The composition of claim 1 , wherein the second ultra high molecular weight polyethylene material has a different average particle size than the first ultra high molecular weight polyethylene material.

6. The composition of claim 5 , wherein the cross-linked form of the first ultra high molecular weight polyethylene material and the cross-linked polymeric material are each present in an amount effective to provide at least a bimodal molecular weight distribution in the composition.

7. The composition of claim 5 , wherein the one or more crystalline and amorphous regions comprise one or more first crystalline regions from the first ultra high molecular weight polyethylene material and one or more second, different crystalline regions from the cross-linked polymeric material.

8. The composition of claim 7 , wherein the one or more second, different crystalline regions have a substantially homogenous distribution throughout the one or more first crystalline regions.

9. The composition of claim 1 , wherein the crystalline regions together comprise about 62% to 90% by volume of the composition.

10. The composition of claim 1 , wherein the crystalline regions together comprise about 62% to 75% by volume of the composition.

11. A method of making a composition of claim 1 , comprising:
forming a blend, including combining a first ultra high molecular weight polyethylene material that is about 80 wt % to about 90 wt % of the blend, a first antioxidant that is vitamin E and that is about 0.2 wt % to about 0.5 wt % of the blend, and a cross-linked polymeric material that is about 10 wt % to about 20 wt % of the blend and that comprises an about 50 kGy to about 200 kGy electron beam irradiation cross-linked form of a blend of a second antioxidant that is about 0.1 wt % to about 0.2 wt % of the cross-linked form of the blend and a second ultra high molecular weight polyethylene material that is the remainder of the cross-linked form of the blend, wherein the cross-linked polymeric material is free of melting after the cross-linking of the blend comprising the second antioxidant and the second ultra high molecular weight polyethylene material, wherein the second ultra high molecular weight polymeric material has a different average molecular weight than the first ultra high molecular weight polyethylene material; and
electron beam irradiation cross-linking the blend of the first ultra high molecular weight polyethylene material, the first antioxidant, and the cross-linked polymeric material with a total dose of about 50 kGy to about 200 kGy to form a composition comprising one or more crystalline and one or more amorphous regions from the cross-linked form of the blend of the first ultra high molecular weight polyethylene material, the first antioxidant, and the cross-linked polymeric material, the crystalline regions together comprising at least 62% by volume of the composition;
wherein the method is free of melting after the irradiation cross-linking of the blend of the first ultra high molecular weight polyethylene material, the cross-linked polymeric material, and the first antioxidant.

12. The method of claim 11 , further comprising selecting the second ultra high molecular weight polyethylene material to be a material with a different average particle size than an average particle size of the first ultra high molecular weight polyethylene material.

13. The method of claim 11 , further comprising mixing the first ultra high molecular weight polyethylene material, the first antioxidant, and the cross-linked polymeric material until the cross-linked polymeric material is present in a substantially uniform distribution throughout the ultra high molecular weight polyethylene material.

Assignees

• Shen Ming C
• Schneider Werner
• Zimmer Gmbh

Inventors

• Shen Ming C
• Schneider Werner

Classifications

• C08L2666/06

  Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof · CPC title

• C08L2201/08

  Stabilised against heat, light or radiation or oxydation · CPC title

• C08L2203/02

  for biomedical use · CPC title

• C08L23/06

  Polyethylene · CPC title

• C08J2323/06

  Polyethene · CPC title