Static seals, compositions, and methods of making the same

Patent metadata

Field	Value
Publication number	US-10689470-B2
Application number	US-201715836325-A
Country	US
Kind code	B2
Filing date	Dec 8, 2017
Priority date	Dec 10, 2016
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A static sealing member is provided that includes a composition having a silane-crosslinked polyolefin elastomer with a density less than 0.90 g/cm 3 . The static sealing member can exhibit a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.). The silane-crosslinked polyolefin elastomer can include a first polyolefin having a density less than 0.86 g/cm 3 , a second polyolefin having a crystallinity less than 40%, a silane crosslinker, a grafting initiator, and a condensation catalyst.

First claim

What is claimed is:

1. A static sealing member comprising:
a composition comprising a silane-crosslinked polyolefin elastomer having a density less than 0.90 g/cm 3 and a crystallinity of from about 5% to about 20%,
wherein from about 1 wt % to about 35 wt % of the silane-crosslinked polyolefin elastomer is a polypropylene filler having a crystallinity greater than 40%,
wherein the silane-crosslinked polyolefin elastomer does not display a Mullins effect or a Payne effect;
wherein the silane-crosslinked polyolefin elastomer and the static sealing member are thermosets; and
wherein the static sealing member exhibits a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.).

2. The static sealing member of claim 1 , wherein the silane-crosslinked polyolefin elastomer further comprises
a first polyolefin having a density less than 0.86 g/cm 3 , wherein the first polyolefin is an ethylene/α-olefin copolymer,
a second polyolefin having a percent crystallinity less than 40%, wherein the second polyolefin is a polypropylene/α-olefin copolymer or a blend of propylene/α-olefin copolymer with an ethylene/α-olefin copolymer,
a silane crosslinker, a grafting initiator, and a non-metal condensation catalyst.

3. The static sealing member of claim 1 , wherein the compression set is from about 15.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.).

4. The static sealing member of claim 1 , wherein the silane-crosslinked polyolefin elastomer comprises from about 3 wt % to about 10 wt % polypropylene filler and has a density is from about 0.85 g/cm 3 to about 0.89 g/cm 3 .

5. The static sealing member of claim 1 , wherein the silane-crosslinked polyolefin elastomer exhibits a crystallinity of from about 5% to about 10%.

6. The static sealing member of claim 1 , wherein the silane-crosslinked polyolefin elastomer exhibits a glass transition temperature of from about −75° C. to about −25° C.

7. The static sealing member of claim 1 , wherein the static sealing member exhibits a weathering color difference of from about 0.25 ΔE to about 2.0 ΔE, as measured according to ASTM D2244.

8. The static sealing member of claim 1 , further comprising:
a coloring agent.

9. A silane-crosslinked polyolefin blend comprising:
a first polyolefin having a density less than 0.86 g/cm 3 , wherein the first polyolefin is an ethylene/α-olefin copolymer;
a second polyolefin having a percent crystallinity less than 40%, wherein the second polyolefin is a polypropylene/α-olefin copolymer or a blend of propylene/α-olefin copolymer with an ethylene/α-olefin copolymer;
from about 1 wt % to about 35 wt % polypropylene filler having a crystallinity greater than 40%;

and
silane crosslinks;
wherein the silane-crosslinked polyolefin blend exhibits a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.),
wherein the silane-crosslinked polyolefin blend is a thermoset,
wherein the silane-crosslinked polyolefin blend exhibits a crystallinity of from about 5% to about 20%, and
wherein the silane-crosslinked polyolefin blend does not display a Mullins effect or a Payne effect.

10. The silane-crosslinked polyolefin blend of claim 9 , wherein the first polyolefin comprises from about 30 wt % to about 70 wt % of the silane-crosslinked polyolefin blend.

11. The silane-crosslinked polyolefin blend of claim 9 , wherein the silane crosslinks are derived from a vinyltrimethoxy silane crosslinker.

12. The silane-crosslinked polyolefin blend of claim 9 , further comprising from about 0.25 wt % to about 8 wt % of a non-metal condensation catalyst.

13. The silane-crosslinked polyolefin blend of claim 9 , wherein the blend comprises from about 3 wt % to about 10 wt % polypropylene filler and has a density from about 0.85 g/cm 3 to about 0.89 g/cm 3 .

14. The silane-crosslinked polyolefin blend of claim 9 , wherein the blend exhibits a crystallinity of from about 5% to about 10%.

15. The silane-crosslinked polyolefin blend of claim 9 , wherein the blend exhibits a glass transition temperature of from about −75° C. to about −25° C.

16. A method for making a static sealing member, the method comprising:
extruding a first polyolefin having a density less than 0.86 g/cm 3 , a second polyolefin having a crystallinity less than 40%, a polypropylene filler having a crystallinity greater than 40%, a silane crosslinker and a grafting initiator together to form a silane-grafted polyolefin blend, wherein the polypropylene filler comprises from about 1 wt % to about 20 wt % of the silane-grafted polyolefin blend;
extruding the silane-grafted polyolefin blend and a condensation catalyst together to form a silane-crosslinkable polyolefin blend;
molding the silane-crosslinkable polyolefin blend into an uncured static sealing element; and
crosslinking the crosslinkable-polyolefin blend of the uncured static sealing element at an ambient temperature and an ambient humidity to form the element into a static sealing member having a density from about 0.85 g/cm 3 to about 0.89 g/cm 3 ,
wherein the first polyolefin is an ethylene/α-olefin copolymer and the second polyolefin is a propylene/α-olefin copolymer or a blend of propylene/α-olefin copolymer with an ethylene/α-olefin copolymer,
wherein the static sealing member exhibits a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.),
wherein the static sealing member exhibits a crystallinity of from about 5% to about 20%,
wherein the static sealing member does not display a Mullins effect or a Payne effect; and
wherein the silane-grafted polyolefin blend and the silane-crosslinkable polyolefin blend exhibit thermoplastic properties and the static sealing member is a thermoset.

17. The static sealing member of claim 1 , wherein the silane-crosslinked polyolefin elastomer exhibits a tensile strength ranging from 10.4 to 14.5 MPa as measured according to ASTM D412 and a Shore A hardness ranging from 76 to 88 as measured according to ASTM D412.

18. The method of claim 16 , wherein the amount of polypropylene filler ranges from about 3 wt % to about 10 wt %.

19. The method of claim 16 , wherein the static sealing member exhibits a tensile strength ranging from 10.4 to 14.5 MPa as measured according to ASTM D412 and a Shore A hardness ranging from 76 to 88 as measured according to ASTM D412.

Assignees

• Cooper Standard Automotive Inc

Inventors

• Gopalan Krishnamachari
• Lenhart Robert J
• Ji Gending
• Herd-Smith Roland

Classifications

• C09K2200/0685

  Containing silicon · CPC title

• C09K2003/1068

  Crosslinkable materials · CPC title

• C09K3/10 Primary

  {Materials in mouldable or extrudable form} for sealing or packing joints or covers (filling pastes C09D5/34) · CPC title

• C08L2312/08

  by silane · CPC title

• C08L2205/03

  containing three or more polymers in a blend · CPC title