MANUFACTURE OF ELECTRICALLY INSULATING PAPER

摘要

PURPOSE:To improve the breakdown strength of an electrically insulating paper, by sandwitching a polyolefine sheet between two sheets of paper comprising polyolefine fibers and kraft pulp, and heating them under pressure to thermoweld the polyolefine boundaries. CONSTITUTION:The highly airtight sheet 1 is laminated between the paper sheets 2 containing polyolefine. The highly airtight sheet 1 consists of a polyolefine film or a sheet of unwoven fabric of polyolefine fibers. The paper sheet 2 is prepared by mixing for example polyolefine fibers having a fiber length in the order of 1.5mm. with kraft pulp. Its airtightness is selected to be at least 10 gareh sec/100cc. The highly airtight sheet 1 and the paper sheets 2 are monolitheically thermowelded under pressure. Thus, the electrically insulating paper the breakdown strength of which is improved can be obtained.