Sheetlike wholly aromatic polyamide shaped article and a method for producing the same
AssigneeTeijin Limited
InventorsTakanori Shinoki, Akio Nakaishi, Michio Yamamoto
Life of this patent
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Abstract
This invention relates to a sheetlike wholly aromatic polyamide shaped article useful as electrical insulating materials excellent in corona resistance (corona durability) and in surface smoothness. The corona durability of said sheetlike shaped article is increased to 150 minutes or above by adding a nonionic polymer flocculant to an aqueous dispersion comprising 10 to 90% by weight of mica particles, preferably treated with a silane coupling agent and 90 to 10% by weight of a wholly aromatic polyamide stock (fibrids and fibers) in obtaining the sheetlike shaped article from the aqueous dispersion by wet shaping.
Claims11
A sheet-like wholly aromatic polyamide shaped article for use as electrical insulating materials produced by wet-shaping from an aqueous dispersion comprising 10 to 90% by weight, based on the total weight of all of the constituent components of the shaped article, of mica particles and 90 to 10% by weight, based on the total weight of all of the constituent components of the shaped article, of a wholly aromatic polyamide stock, which is composed of wholly aromatic polyamide fibrids and wholly aromatic polyamide fibers, and wherein said shaped article contains a nonionic polymer flocculant and has a corona durability of 150 minutes or above under a load voltage of 20 kv/mm at AC frequency of 1,000 hz.
A method for producing a sheetlike wholly aromatic polyamide shaped article for use as electrical insulating materials, which comprises adding a nonionic polymer flocculant in an amount of 0.01 to 100 ppm based on the amount of water in said aqueous dispersion to said aqueous dispersion which comprises 10 to 90% by weight, based on the total weight of all of the constituent components of the shaped article, of mica particles which are pretreated with a silane coupling agent and 90 to 10% by weight, based on the total weight of all of the constituent components of the shaped article, of a wholly aromatic polyamide stock as principal compounding components which is composed of wholly aromatic polyamide fibrids and wholly aromatic polyamide fibers, and then shaping the sheetlike shaped article according to a papermaking or pulp molding method from said aqueous dispersion.
Dependencies are inferred from the claim text.