. . "As the compound having the double bond to be used for introduction of the polymerizable double bond into the polyurethane and hydroxyl group, there may be included, for example, hydroxyalkyl acrylate and hydroxyalkyl methacrylate such as 2-hydroxyethyl acrylate, 2-hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 2-hydroxyoc" . .