Radiation-proof sheath material and radiation-proof cable

1. A radiation-proof sheath material, comprising:

a chlorinated polyethylene containing molecular chains of ethylene units as a main component in which side chain groups containing chloro groups therein are randomly distributed and cross-linked;

an antioxidant comprising an amine-based antioxidant and a sulfur-based antioxidant, and comprising 1 or more parts by wt. to 100 parts by wt. of the chlorinated polyethylene;

a processing aid comprising from 10 parts by wt. to 50 parts by wt., to 100 parts by wt. of the chlorinated polyethylene; and

a flame retardant comprising from 2 parts by wt. to 30 parts by wt., to 100 parts by wt. of the chlorinated polyethylene.

2. The radiation-proof sheath material according to claim 1 , wherein the processing aid comprises a petroleum-based oil, or an aromatic ring-containing plasticizer.

3. The radiation-proof sheath material according to claim 2 , wherein the processing aid comprises the petroleum-based oil, and the petroleum-based oil comprises an aromatic-based oil.

4. A radiation-proof cable, comprising:

a radiation-proof sheath material comprising a polymer material containing molecular chains of ethylene units as a main component in which side chain groups are randomly distributed and cross-linked, an antioxidant comprising an amine-based antioxidant and a sulfur-based antioxidant added in the polymer material, a processing aid, and a flame retardant; and

a conductor covered with an insulation material, or a stranded insulated electric wire (core) comprising plural stranded conductors, each covered with the insulation material, the conductor or the stranded insulated electric wire (core) provided with the radiation-proof sheath material therearound.

5. The radiation-proof cable according to claim 4 , wherein the oxygen index of the radiation-proof sheath material is greater than the oxygen index of the insulation material.