METHOD OF FORMING OPTICAL PATTERN IN POLYETHYLENE TEREPHTHALATE RESIN MADE PRODUCT AND METHOD OF REINFORCING OPTICAL PATTERN FORMED BY THE SAID METHOD

摘要

PURPOSE:To improve a production rate of a crystalnucleus and to form an optical pattern in a preset shape by changing a light transmission factor, by a method wherein a desired shaped portion is cooled slowly when operations necessary to cool polyethylene terephthalate resin made product for hardening are performed. CONSTITUTION:A desired shape concavity 4 grooved to the desired depth is provided in either 3 (an external surface in a drawing) an external or internal surface of a plastic resin primary molded product 1, and a wall portion 6 is injection-molded by the use of polyethylene terephthalate resins with the surface 3 served as a part of a mold surface. When operations necessary to cool the said wall portion 6 for solidifying are performed, a cooling capacity and cooling rate are controlled so that a filled portion 7, of the wall portion 6, positioned in the concavity 4 can be cooled slowly. And thereby crystalnucleus of the polyethylene terephthalate resins are produced to form an optical pattern. A piece P so produced is heated again to a temperature at which a biaxial stretching effect is produced, and a bottle B is biaxial- stretching-blow-molded. The operations necessary to heat and cool thereupon produce the crystalnucleus at a high rate, which results in heightening the optical effect.