Patent ID: 6045966
Filing Date: 2000-04-04
Classification: C08G,G03F

Abstract:
A method for producing a film forming novolak resin which comprises:a) condensing formaldehyde with one or more phenolic compounds, in the presence of an acid catalyst and thereby producing a novolak resin condensation product, and then removing unreacted phenolic compounds;b) adding a photoresist solvent, thereby forming a solution of the novolak resin condensation product, then adding a water soluble organic polar solvent and water to the solution of the novolak resin condensation product, at a ratio of photoresist solvent:water soluble organic polar solvent:water of 1-9:1-5:3-7, and separating the solution into two layers, a top solution layer and a bottom solution layer, and then removing the top layer,c) adding a water soluble organic polar solvent and water to the bottom layer solution remaining after step b), in the ratio of water soluble organic polar solvent:water of 1:10 to 10:1, thereby separating the bottom layer solution from step b) into two layers, a top solution layer and a bottom solution layer, and then removing the top layer;d) removing any remaining water and water soluble organic polar solvent from the bottom solution layer resulting from step c), and thereby producing a film forming, fractionated novolak resin solution.