Patent ID: 7976901

Claim:
A wet film manufacturing method of a polymeric foam sheet for a polishing sheet, comprising the steps of; coating approximately uniformly a polyurethane resin emulsion, which includes a polyurethane resin, a first organic solvent that the polyurethane resin can be dissolved, and a second organic solvent whose solubility to water is smaller than that of the first organic solvent and which controls coagulation of the polyurethane resin, to a base material; and soaking the base material coated by the polyurethane resin emulsion into a coagulation liquid whose main component is water, such that the resulting polymeric foam sheet has a polishing layer which is disposed inside a layer that defines a surface of the sheet, the polishing layer having a thickness which is greater than a thickness of the surface-defining layer, and the polishing layer having an approximately uniform distribution of foams to a plane orthogonal to a direction of the thickness of the polymeric foam sheet, said foams formed in the polishing layer having a volume larger than that of foams formed in the surface layer and which are communicated by a network of continuous holes, wherein a structure of said polishing layer foams remains substantially constant throughout said thickness of said polishing layer, wherein the second organic solvent is ethyl acetate, and the polyurethane resin emulsion is prepared by adding the second organic solvent of a range of from 20 parts to 45 parts to a polyurethane resin solution, that the polyurethane resin is dissolved into the first organic solvent, of 100 parts.