. "The base material used may be a simple acrylic ester or methacrylate ester or a copolymer thereof such as polymethyl methacrylate or polymethyl acrylate, polyester such as polyethylene terephthalate or polybutylene terephthalate, thermoplastic resin such as polycarbonate, polyethylene, or polymethylpentene, acrylate such as polyfunctional urethane acrylate, crosslinked by means of ultraviolet rays" . . .