Mitsubishi Paper Mills Limited

Mitsubishi Electric Corporation

Masahiro Amano

Takashi Koike

Shunji Seino

Ryota Nishiyama

Masaoki Nozaki

Hidenori Kawakami

Yutaka Gamou

An aqueous slurry comprising fibrous particles of a heat-resistant aromatic polymer and short fibers made of said polymer or insulating inorganic short fibers, or a mixture thereof, is made into a wet web and, after adjusting the water content to 50 to 95 weight %, said wet web is laid up in a desired number of layers, and then the laminate is dewatered and dried for integration under pressure at a temperature not exceeding the softening point of said aromatic polymer, thereby obtaining an oil-impregnatable insulating board with high strength and capable of uniform impregnation of oil therein.

Oil-impregnatable insulating board

A heat resistant thin paper excellent in electrical insulating property can be obtained by subjecting pulp-like particles of aromatic polyamide or aromatic polyamide-imide, which have a low freeness and a low ion content to wet paper-making process, drying and then making the resulting web dense under a pressure.

Process for producing fibrous sheet

A fibrous sheet having a high strength and water resistance and having no resin specks on the surface can be produced by producing a sheet from a fiber slury by the known paper making process, to said fiber slurry being added a flocculate of chlorinated polymer latices which has a particle size of 100.mu.-500 .mu. and is prepared by heating said chlorinated polymer latices to a temperature of at least their minimum film-forming temperature and then adding a water soluble cationic polymer or a polyvalent metal salt with stirring. Examples of said chlorinated polymer latices are anionic polyvinyl chloride latex, polyvinylidene chloride latex or the combination thereof.

Method for producing fibrous sheet

A transparent cellulosic paper is produced by coating or impregnating a cellulosic paper with an organic solvent solution containing a compound having a weight-average molecular weight of 200 to 2,000 and having at least two isocyanate groups in a molecule or with an organic solvent solution containing, in addition to said compound, at least one compound selected from the group consisting of an aliphatic monohydric alcohol having 6 to 18 carbon atoms and a nonionic surface active agent to the polyethylene glycol type having one hydroxyl group in a molecule, the ratio OH/NCO in the solution being less than 1; removing said organic solvent; and allowing the coated or impregnated paper to harden by aging.

Transparent cellulosic paper and method for making the same

A fibrous sheet bonded with a latex flocculate is produced by adding zinc white powders to a carboxyl modified anionic latex, adjusting the pH to at least 7, adding thereto a water soluble cationic polymer to obtain a latex flocculate, adding thus obtained flocculate to a fiber slurry and subjecting the fiber slurry to a known wet paper making process.

Growing community of inventors

Tokyo, Japan

Masahiro Amano