Claims
- 1. A method for the formation of a strippable semiconductive shield comprising the steps of adding a conductive carbon black in an amount sufficient to give the strippable semiconductive shield an electrical resistivity below 500 Ωm and an adhesive-adjusting additive of a copolymer which consist essentially of ethylene and a comonomer having in its molecule at least one carbon-oxygen dipple, said copolymer having a molecular weight less than 20,000 daltons but a Mettler drop point higher than 30° C. to a base polymer which is a copolymer of ethylene with a mono-unsaturated ester, when the adhesive-adjusting additive is 1-20% by weight of the base polymer;blending said conductive carbon black, said adhesion-adjusting additive and said base polymer and extruding said blended conducting carbon black, adhesive-adjusting additive and base polymer to form the strippable semiconductive shield.
- 2. The method of claim 1 where said base polymer is an ethylene vinyl acetate.
- 3. The method of claim 2 wherein the resistivity is in the range from 5 to 100 Ωm.
- 4. The method of claim 2 wherein the ethylene vinyl acetate base polymer has a vinyl acetate content of about 33%.
- 5. The method of claim 1 wherein said base polymer is selected from the group consisting of ethylene-ethyl acrylate, ethylene-methyl acrylate, ethylene-methyl methacrylate copolymers and ternary (or higher order) copolymers containing relatively small amounts of at least one additional monomer.
- 6. The method of claim 5 wherein the resistivity is in the range from 5 to 100 Ωm.
- 7. The method of claim 1 wherein the adhesion-adjusting additive comprises a comonomer with at least one C—O single-bond (ether) dipole.
- 8. The method of claim 1 wherein the adhesion-adjusting additive comprises a comonomer with at least one C═O double bond (carbonyl) dipole.
- 9. The method of claim 1 wherein the adhesion-adjusting additive comprises a comonomer with at least one C:O—O (ester) dipole.
- 10. The method of claim 1 wherein the adhesion-adjusting additive comprises 1 to 20 weight percent of the strippable semiconducting shield.
- 11. The method of claim 10 wherein said adhesion-adjusting additive comprises 2-10 weight percent of the strippable semiconductive shield.
- 12. The method of claim 1 wherein its adhesion-adjusting additives is an ehtylene vinyl acetate.
- 13. The method claim 12 wherein the adhesion-adjusting ehtylene vinyl acetate has a vinyl acetate composition of about 12%.
- 14. The method of claim 12 where the adhesion adjusting ethylene vinyl acetate has a vinyl acetate comprised of about 14%.
- 15. The method of claim 12 wherein the adhesion adjusting ehtylene vinyl acetate has a vinyl acetate composition of about 11%.
Parent Case Info
This application is a Continuation of application Ser. No. 09/202,028 filed on Jan. 8, 1999.
US Referenced Citations (9)
Foreign Referenced Citations (2)
Number |
Date |
Country |
210425 |
Feb 1987 |
EP |
4202771 |
Apr 1991 |
EP |
Continuations (1)
|
Number |
Date |
Country |
Parent |
09/202028 |
Jan 1999 |
US |
Child |
09/698178 |
|
US |