| 摘要 |
A process for producing a polyurethane resin of the present invention includes a step (i) of obtaining a prepolymer by adding an alcohol (B) to isocyanate (A) such that a ratio of hydroxyl groups to isocyanato groups of the isocyanate (A) falls into a range of 10 mol% to 20 mol% and reacting the isocyanate (A) with the alcohol (B) in the presence of an acidic phosphoric acid ester (C) and a hindered amine-based compound (D), a step (ii) of obtaining a polymerizable composition in a manner in which the alcohol (B) is further added to and mixed with the prepolymer at a temperature of equal to or less than 30°C, and a step (iii) of polymerizing the prepolymer and the alcohol (B) contained in the polymerizable composition. The isocyanate (A) is one or more kinds of isocyanate having two or more isocyanato groups, which contains aromatic isocyanate. The alcohol (B) includes one or more kinds of alcohol having two or more hydroxyl groups. In the alcohol (B), a ratio of secondary hydroxyl groups to a total molar number of primary and secondary hydroxyl groups is equal to or greater than 50 mol%. |
