Abrasive sheet and process for producing the same

A process for producing an abrasive sheet comprising the steps of:

• evenly dispersing 2 to 80 parts by volume of abrasive particles having an average size of 0.1 to 50 .mu.m in an organic polar solvent;
• mixing the resultant dispersion with a polymerization mixture consisting essentially of a tetracarboxylic acid component comprising, as a major acid ingredient, at least one member selected from the group consisting of biphenyltetracarboxylic acids and dianhydrides thereof and a diamine component comprising at least one aromatic diamine;
• polymerizing the acid and diamine components at a temperature of 0.degree. C. to 80.degree. C., to provide a dope dispersion consisting essentially of a solution of an aromatic polyamic acid dissolved in the organic polar solvent having the abrasive particles evenly dispersed in the aromatic polyamic acid solution;
• forming the dope dispersion into a thin layer thereof;
• and
• solidifying the thin layer of the dope dispersion by evaporating the organic polar solvent,
• imidizing the aromatic polyamic acid to the corresponding aromatic imide polymer to provide an abrasive sheet, and
• the polymerization mixture being provided in an amount necessary to provide the corresponding aromatic imide polymer in an amount of 20 to 98 parts by volume of the abrasive sheet.

An abrasive sheet comprising 20% to 98% by volume of a matrix comprising an aromatic imide polymer resin which is a polymerization-imidization product of a tetracarboxylic acid component comprising, as a major acid ingredient, at least one member selected from the group consisting of biphenyltetracarboxylic acids and dianhydrides thereof with adiamine component comprising at least one aromatic diamine, and 2% to 80% by volume of abrasive particles having an average size of 0.1 to 50 .mu.m evenly dispersed in the matrix, produced by the process which comprises:

• evenly dispersing 2 to 80 parts by volume of abrasive particles having an average size of 0.1 to 50 .mu.m in an organic polar solvent;
• mixing the resultant dispersion with a polymerization mixture consisting essentially of a tetracarboxylic acid component comprising, as a major acid ingredient, at least one member selected from the group consisting of biphenyltetracarboxylic acids and dianhydrides thereof and a diamine component comprising at least one aromatic diamine;
• polymerizing the acid and diamine components at a temperature of 0.degree. C. to 80.degree. C., to provide a dope dispersion consisting essentially of a solution of an aromatic polyamic acid dissolved in the organic polar solvent having the abrasive particles evenly dispersed in the aromatic polyamic acid solution;
• forming the dope dispersion into a thin layer thereof;
• and
• solidifying the thin layer of the dope dispersion by evaporating the organic polar solvent,
• imidizing the aromatic polyamic acid to the corresponding aromatic imide polymer to provide an abrasive sheet, and
• the polymerization mixture being provided in an amount necessary to provide the corresponding aromatic imide polymer in an amount of 20 to 98 parts by volume of the abrasive sheet.