Patents Assigned to Tohoku Munekata Company Limited
  • Patent number: 6203731
    Abstract: If the surface of metallic mold should not be highly transcribed to the surface of product in injection molding the plastic products, the transcription defects such as weld, shrinkage, etc. are caused to the surface of product. Further, if the resin should be exposed to the surface of high temperature metallic mold more than necessary during the molding, the filler and the like of glass and so forth are contained into the resin, and in this case, they are left over on the surface of metallic mold, resulting in the transcription defect. These problems can be solved by heating the surface temperature of metallic mold higher than the glass transfer temperature of resin if the resin is non-crystal and higher than the fusion point temperature if the resin crystal, with the temperature raising speed of more than 2° C. every second, maintaining this temperature during the resin charging, and by cooling at the lowering speed of more than 2° C. every second after the completion of charging.
    Type: Grant
    Filed: October 16, 1998
    Date of Patent: March 20, 2001
    Assignee: Tohoku Munekata Company Limited
    Inventors: Tsuyoshi Kato, Hirofumi Tateyama, Hideyuki Ishiyama, Kiyoshi Suzuki