Insulating resin composition and production method therefor, insulating tape and production method therefor, insulating layer formation method, and power cable and production method therefor

A method of producing an insulating resin composition, the method comprising:

• adding an unmodified polyolefin resin and an antioxidant to a polyolefin resin modified with at least one polar group-containing molecule selected from an unsaturated dicarboxylic acid, an unsaturated dicarboxylic acid anhydride, and an unsaturated dicarboxylic acid anhydride derivative;
• and
• kneading the unmodified polyolefin resin, the antioxidant, and the modified polyolefin resin to obtain a base resin that comprises a dilution of the modified polyolefin resin with the unmodified polyolefin resin and has what is called a sea-island structure comprising:
• a first phase comprising the unmodified polyolefin resin;
• and a second phase provided in the first phase and comprising the modified polyolefin resin, wherein the second phase has an average diameter of 2 μm or less.

A method of producing an insulating resin composition, the method comprising:

• adding an unmodified polyolefin resin and an antioxidant to a polyolefin resin modified with at least one polar group-containing molecule selected from an unsaturated dicarboxylic acid, an unsaturated dicarboxylic acid anhydride, and an unsaturated di carboxylic acid anhydride derivative to prepare diluted polyolefin pellets comprising a base resin comprising a dilution of the modified polyolefin resin with the unmodified polyolefin resin;
• then adding a cross-linking agent to the diluted polyolefin pellets;
• and subjecting the cross-linking agent and the diluted polyolefin pellets to dry blending such that the base resin has what is called a sea-island structure comprising:
• a first phase comprising the unmodified polyolefin resin;
• and a second phase provided in the first phase and comprising the modified polyolefin resin and the second phase has an average diameter of 2 μn or less.