Electrical insulating laminated paper, process for producing the same oil-impregnated power cable containing the same

An oil-impregnated power cable comprising:

• a conductor;
• and
• an insulating layer at least part of which is formed by winding an insulating laminated paper comprising:
• at least one sheet of a kraft insulating paper;
• and
• a plastic film layer comprising a polyolefin resin;
• said kraft insulating paper and said plastic film layer having been integrated by melt extrusion to form an insulating laminated paper and said insulating laminated paper having been calendered or supercalendered subsequent to said kraft insulating paper and said plastic film layer having been integrated whereby, after having been subjected to said calendering or supercalendering, the laminated paper has at least one sheet of kraft insulating paper having a smooth outer surface and a relatively rough inner surface in contact with said polyolefin resin;
• said insulating laminated paper having a thickness of approximately 30 to 200 μm;
• and
• said plastic film layer having a thickness of approximately 40 to 90% of the thickness of said insulating laminated paper.