Crosslinkable blends of polyolefin elastomers and silane copolymers for increased flexibility cable insulation
Compositions having at least 60 weight percent, based on the total weight of polymers, have at least one silane crosslinkable polyolefin resin and up to about 40 weight percent, based on the total weight of polymers, of at least one polyolefin elastomer resin, wherein the polyolefin polymer elastomer resin has density of less than or equal to about 0.89 g/cm 3 and a melt index, I 2 , of less than about 50 g/10 mm. and which has been prepared using at least one metallocene catalyst provide improved flexibility, especially low temperature flexibility, while maintaining suitable cure performance and strength compared to the silane crosslinkable polymer resin alone. This composition may be used in cables for low temperature service applications.
1. A composition comprising:
at least about 60 weight percent, based on the total weight of polymer resins, of at least one silane crosslinkable polyolefin polymer resin; and,
at least one substantially linear ethylene polymer elastomer resin present in an amount of about 20 weight percent to about 40 weight percent, based on the total weight of polymers, wherein the polymer elastomer resin has a density of less than or equal to about 0.89 g/cm 3 and a melt index, I 2 , of less than about 50 g/10 min.;
wherein the composition has a flexural modulus at −30° C. between 595 and 1050 MPa.
2. The composition of claim 1 wherein the silane crosslinkable polyolefin polymer is a copolymer of ethylene with a vinyl silane comonomer.
3. The composition of claim 1 wherein the silane crosslinkable polyolefin polymer is a copolymer of ethylene-vinyltrimethoxysilane.
4. The composition of claim 1 wherein the polymer elastomer resin is present in amount at least 30 weight percent based on the total weight of the polymers.
5. The composition of claim 1 wherein the polymer elastomer resin is present in an amount of about 40 weight percent based on the total weight of the polymers.
6. The composition of claim 1 wherein the polymer elastomer resin has a density of less than or equal to about 0.885 g/cm 3 .
7. The composition of claim 1 wherein the polymer elastomer resin has a melt index, I 2 , of between about 1 to about 40 g/10 min.
8. The composition of claim 1 wherein the polymer elastomer resin has a melt index, I 2 , of between about 1 to about 30/10 min.
9. The composition of claim 1 further comprising at least one of fillers, flame-retardants, pigments, antioxidants and catalysts.
10. A cable comprising:
a conductive core; and,
a layer of an insulating material outside of the conductive core, wherein the insulating material comprises a composition comprising at least about 60 weight percent, based on the total weight of polymer resins, of at least one silane crosslinkable polyolefin polymer resin; and, of about 20 weight percent to about 40 weight percent, based on the total weight of polymers, of at least one substantially linear ethylene polymer elastomer resin, wherein the polymer elastomer resin has a density of less than or equal to about 0.89 g/cm 3 and a melt index, I 2 , of less than about 50 g/10 min.;
wherein the composition has a flexural modulus at −30° C. between 595 and 1050 MPa.
11. The cable of claim 10 wherein the silane crosslinkable polyolefin polymer is a copolymer of ethylene with a vinyl silane comonomer.
12. The cable of claim 10 wherein the composition silane crosslinkable polyolefin polymer is ethylene-vinyltrimethoxysilane.
13. The cable of claim 10 wherein the composition polymer elastomer resin is present in amount of at least 20 weight percent based on the total weight of the polymers.
14. The cable of claim 10 wherein the composition polymer elastomer resin is present in amount at least 30 weight percent based on the total weight of the polymers.
15. The cable of claim 10 wherein the composition polymer elastomer resin is present in an amount of about 40 weight percent based on the total weight of the polymers.
16. The cable of claim 10 wherein the composition polymer elastomer resin has a density of less than or equal to about 0.885 g/cm 3 .
17. The cable of claim 10 wherein the composition polymer elastomer resin has a melt index, I 2 , of between about 1 to about 40 g/10 min.
18. The cable of claim 10 wherein the composition polymer elastomer resin has a melt index, I 2 , of between about 1 to about 30 g/10 min.
19. The cable of claim 10 wherein the composition further comprising at least one of fillers, flame-retardants, pigments, antioxidants and catalysts.