Method and apparatus for producing blow mouldings

摘要

Provided is a method for producing blow moldings having a relatively large size through blow molding by use of a simple facility. Faithful mold-to-resin transfer of a surface such as a glossy surface is attained, and moldings can be obtained in shorter cycles with improved productivity. The method comprising the steps of feeding a melt parison of crystalline resin into the'space between molds, clamping the molds, blowing a pressurized fluid into the interior of the parison so as to cause the parison to be into close contact with the inner surfaces of the molds and to solidify the parison, wherein, while the parison and the mold inner surfaces are in close contact, the temperature of inner surfaces of the molds is maintained at a temperature from a temperature 10 DEG C lower than the crystallization temperature of the crystalline resin to the melting point of the resin, and the parison is removed from the molds after the parison is cooled through introduction thereinto or discharge therefrom, during or after blowing-in of the pressurized fluid, of a cooling medium not higher than room temperature. An apparatus comprises a blow molding machine; a forming mold which is used in combination with the blow molding machine for producing a blow molding, the forming mold having degassing pores having a diameter of 100 mu m or less in the surface of the mold at intervals (a pitch) of 50 mm or less; and means for introducing and/discharging a cooling medium into or from a parison formed through the mold. <IMAGE>