| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a carboxyl-containing polyurethane resin solution for a photosensitive planographic printing plate having simpler production steps than a conventional method and capable of reducing the production cost. SOLUTION: In the production of a polyurethane resin solution (C) for a photosensitive planographic printing plate comprising a carboxyl-containing polyurethane resin (A) obtained by reacting a polyether polyol (a1) having a hydroxyl equivalent of 50-1,500 and a polyhydroxycarboxylic acid (a2) as polyol components (a) with an excess of an organic polyisocyanate (b) and sealing the resulting isocyanate-containing polyurethane resin (A1) having an isocyanate equivalent of 6,000-25,000 with a sealant (c) comprising an aliphatic monohydric alcohol and an organic solvent (B) having 100-200 deg.C boiling point, the urethane forming and sealing reactions are carried out in a polar organic solvent (d) having <=70 deg.C boiling point and inert to the isocyanate, the solvent (B) is added to this solution and the solvent (d) is distilled out. |
