Semiconductive polymer composition
The invention relates to a semiconductive polymer composition comprising a polymer component, a conducting component and a crosslinking agent, wherein the polymer component comprises a polar polyethylene and the crosslinking agent comprises an aliphatic mono- or bifunctional peroxide or, alternatively, a monofunctional peroxide containing an aromatic group, and the crosslinking agent is present in an amount which is Z wt %, based on the total amount (100 wt %) of the polymer composition, and Z 1 ≤Z≤Z 2 , wherein Z 1 is 0.01 and Z 2 is 5.0, an article being e.g. a cable, e.g. a power cable, and processes for producing a semiconductive polymer composition and an article; useful in different end applications, such as wire and cable (W&C) applications.
1. A cable comprising a semiconductive polymer composition, wherein the semiconductive polymer composition comprises:
a polymer component,
a conducting component, and
a crosslinking agent,
wherein:
the polymer component comprises a polar polyethylene, wherein the polar polyethylene is a polyethylene copolymer with one or more polar comonomers selected from (meth)acrylates, olefinically unsaturated carboxylic acids, (meth)acrylic acid derivatives, and vinyl ethers; and
the crosslinking agent is selected from 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and/or tert-butyl cumyl peroxide; and
the crosslinking agent is present in an amount which is Z wt %, based on a total amount (100 wt %) of the semiconductive polymer composition, and 0.2≤Z≤1.5.
2. The cable according to claim 1 , wherein the polar polyethylene is a low-density polyethylene (LDPE) copolymer having at least a polar comonomer.
3. The cable according to claim 1 , wherein the polar polyethylene further comprises unsaturation provided by copolymerizing ethylene with at least one polyunsaturated comonomer and/or by using a chain transfer agent or propylene.
4. The cable according to claim 1 , wherein the one or more polar comonomers are selected from methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, hydroxyethyl(meth)acrylate, (meth)acrylic acid, maleic acid, fumaric acid, (meth)acrylonitrile, (meth)acrylic amide, vinyl methyl ether, or vinyl phenyl ether.
5. The cable according to claim 1 , wherein the polar polyethylene is a polyethylene copolymer of ethylene with at least methyl acrylate, a polyethylene copolymer of ethylene with at least ethyl acrylate, or a polyethylene copolymer of ethylene with at least butyl acrylate.
6. The cable according to claim 1 , wherein a content of the one or more polar comonomers in the polar polyethylene copolymer is up to 70 wt % of a total amount of the polar polyethylene.
7. The cable according to claim 1 , wherein a content of one or more polar comonomers in the polar polyethylene is 0.5 to 35 wt % or 1.0 to 35 wt % of a total amount of the polar polyethylene.
8. The cable according to claim 1 , wherein the semiconductive polymer composition comprises:
35 to 90 wt % of the polymer component,
10 to 60 wt % of a conducting component comprising carbon black, and
0 to 8 wt % additives,
wherein all wt % are based on the total amount of the semiconductive polymer composition.
9. The cable according to claim 1 , wherein the conducting component comprises carbon black and the carbon black is present in an amount from 10 to 60 wt %, 10 to 50 wt %, 20 to 45 wt %, 30 to 40 wt %, or 35 to 40 wt %, based on the total amount of the semiconductive polymer composition.
10. The cable according to claim 1 , wherein the conducting component comprises a conductive carbon black with one or more of the following properties:
a primary particle size of at least 5 nm which is defined as a number average particle diameter according to ASTM D3849-95a procedure D;
an iodine adsorption number (IAN) of at least 10 mg/g when determined according to ASTM D-1510-07; or
a DBP (dibutyl phthalate) absorption number (oil number) of at least 30 cm 3 /100 g when measured according to ASTM D 2414-06a.
11. The cable according to claim 10 , wherein:
the iodine adsorption number (IAN) of the conductive carbon black is from 10 to 300 mg/g when determined according to ASTM D-1510-07;
the DBP (dibutyl phthalate) absorption number (oil number) of the conductive carbon black is from 60 to 300 cm 3 /100 g when measured according to ASTM D 2414-06a;
or a combination thereof.
12. The cable according to claim 1 , wherein the crosslinking agent comprises 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.
13. The cable according to claim 1 , wherein the crosslinking agent comprises tert-butyl cumyl peroxide.
14. The cable according to claim 1 , wherein Z is from 0.3 to 1.0.
15. The cable according to claim 1 , wherein the semiconductive polymer composition has a scorch performance, (scorch time) of at least 20 minutes when determined in accordance with Method 6.
16. The cable according to claim 1 , wherein the cable is a power cable.
17. A process for producing the cable according to claim 1 , which process comprises using the semiconductive polymer composition to produce the cable, wherein the process comprises extruding the semiconductive polymer composition onto a conductor, thereby forming at least one semiconductive polymer layer on a conductor.