Stabilized medium and high voltage cable insulation composition

• US 20020198344A1
• Filed: 04/05/2002
• Published: 12/26/2002
• Est. Priority Date: 04/10/2001
• Status: Active Grant

• Current Assignee: CIBA Specialty Chemicals
• Original Assignee: CIBA Specialty Chemicals
• Inventors: Voigt, Wolfgang, Kenny, John
• Granted Patent: US 7,056,967 B2
• Time in Patent Office: Days
• US Class Current: 526/201
• CPC Class Codes: H01B 3/441 from alkenes

Abstract

The invention relates to a polyethylene composition for use as insulation for wire and cable that has improved scorch resistance comprising

(a) a polyethylene

(b) a scorch inhibitor having a melting point below 50° C. at atmospheric pressure, and

(c) an organic peroxide.

Claims

1. A composition comprising

(a) a polyethylene

(b) a scorch inhibitor having a melting point below 50°

C. at atmospheric pressure, and

(c) an organic peroxide.

2. A composition according to claim 1, wherein the scorch inhibitor is a compound of the formula I

3. A composition according to claim 2, wherein

R¹ is C_1-20alkyl, and

R² and R³ are identical and are C_1-20alkyl or C_1-20alky substituted by one or two hydroxyl.

4. A composition according to claim 2, wherein the scorch inhibitor of formula I is 2,4-bis(n-octylthiomethyl)-6-methylphenol or 2,4-bis(n-dodecylthiomethyl)-6-methylphenol.

5. A composition according to claim 1, wherein the scorch inhibitor is a compound of the formula II or III or mixtures thereof

6. A composition according to claim 1, wherein the scorch inhibitor is a mixture containing an amine selected from diphenylamine, 4-tert.-butyldiphenylamine, 4-tert.-octyldipenylamine, 4,4′

-di-tert.-butyldiphenylamine, 2,4,4′

-tris-tert.-butyldiphenylamine, 4-tert.-butyl-4′

-tert.-octyldiphenylamine, o,o′

-, m,m′

- or p,p′

-di-tert.-octyldiphenylamine, 2,4-di-tert.-butyl-4′

-tert.-octyldiphenylamine, 4,4′

-di-tert.-octyldiphenylamine, 2,4-di-tert.-octyl-4′

-tert.-butyldiphenylamine, and in addition a phenol according to formula I, II, or III according to claims 2 and 5 or a phenol selected from the following phenols;

7. A composition according to claim 6, wherein the amine is 4,4′

-di-tert.-octyldiphenylamine or Amine (A) which is a mixture of;

3 wt % diphenylamine, 14 wt % 4-tert.-butyldiphenylamine, 30 wt % (4-tert.-octyldiphenylamine 4,4′

-di-tert.-butyldiphenylamine and 2,4,4′

-tris-tert.-butyldiphenylamine), 29 wt % (4-tert.-butyl-4′

-tert.-octyldiphenylamine, o,o′

, m,m′

or p,p′

-di-tert.-octyldiphenylamine and 2,4-di-tert.-butyl-4′

-tert.-octyldiphenylamine), 18 wt % 4,4′

-di-tert.-octyldiphenylamine and 6 wt % 2,4-di-tert.-octyl-4′

-tert.-butyldiphenylamine.

8. A composition according to claim 6, wherein the scorch inhibitor is a mixture of 80 wt % 4,4′

-di-tert.-octyldiphenylamine and 20 wt % of Phenol P.

9. A composition according to claim 1, wherein the amount of scorch inhibitor is in the range from 0.01 to 1 wt % and the amount of the peroxide is in the range from 0.5 to 5 wt %.

11. A composition according to claim 3, wherein the scorch inhibitor of formula I is 2,4-bis(n-octylthiomethyl)-6-methylphenol or 2,4-bis(n-dodecylthiomethyl)-6-methylphenol.

10. A process for preparing a crosslinked polyethylene composition whereby the polyethylene or the polyethylene/peroxide blend is introduced into an extruder and the scorch inhibitor having a melting point below 50°

C. or the scorch inhibitor and the peroxide is added to said extruder and whereby the extrudate is then crosslinked by exposing it to a temperature greater than the decomposition temperature of which the organic peroxide decomposes.