Method for injection molding of plastic products having excellent transcription properties

A method for obtaining at a low pressure high transcription plastic products with a metallic molding of plastic product using a metallic mold, the method comprising the steps of:

• closing the metallic mold;
• injecting a plastic product resin material into the closed mold;
• subsequent to said step of injecting, maintaining the pressure in the mold at a fill level for a period of time;
• cooling the mold;
• opening the metallic mold;
• removing the molded product from the opened metallic mold;
• directly incorporating a temperature detection sensor in close proximity to the surface of molding surface material layer of metallic mold;
• heating and cooling the metallic mold using a thermal medium pipe channel integrally provided in the metallic mold, the thermal pipe carrying thermal medium;
• controlling the temperature of heating and cooling by supplying thermal medium to the thermal medium pipe channel of metallic mold from a metallic mold temperature adjusting machine based on the molding surface temperature of metallic mold detected with the temperature detection sensor, and also controlling the temperature to a level higher than the fusion point temperature of resin if the material resin is crystal, and to a level higher than the glass transfer temperature of resin if the material resin is non-crystal including controlling the heating thermal medium so that the surface temperature of metallic mold has a temperature rising speed of more than 2° C. every second during said step of injection, up to said level, and after maintaining this temperature during further injection, controlling the temperature of cooling thermal medium being supplied to the metallic mold after the completion of injection so that the surface temperature of metallic mold may lowered at a rate of more than 2° C. every second.

A method for obtaining at a low pressure high transcription plastic products with a metallic molding of plastic product using a metallic mold, the method comprising the steps of:

• closing the metallic mold;
• injecting a plastic product resin material into the closed mold;
• subsequent to said step of injecting, maintaining the pressure in the mold at a fill level for a period of time;
• cooling the mold;
• opening the metallic mold;
• removing the molded product from the opened metallic mold;
• controlling the temperature of heating the metallic mold within a short time and in high speed with the metallic mold surface temperature, in contact with the product, being raised from about 2° C. every second to 3° C. every second until said metallic mold surface temperature is at a level higher than the glass transfer temperature of the resin if the resin material is non-crystal and being raised about 2° C. every second until said metallic mold surface temperature is at a level higher than the fusion point temperature of resin if the material resin is crystal;
• maintaining said metallic mold surface temperature during said step of injecting, subsequent to reaching one of said level higher than the glass transfer temperature and said level higher than the fusion point temperature;
• and
• after the completion of injection, cooling down said metallic mold surface temperature within a short time and at a high speed with the temperature lowering speed of more than 2° C. every second.