Patent ID: 6929763
Filing Date: 2005-08-16
Classification: B29C

Abstract:
1. An injection molding method comprising supplying a gas into a molten resin in a plasticizing cylinder and injecting the molten resin having the gas dissolved therein, wherein when the resin is being plasticized, a gas space with a predetermined gas pressure is formed within the plasticizing cylinder in a gas supply section and the pressure at the front end of a screw is adjusted to be at least equal to the gas pressure in the gas space and within a range where the gas space can be maintained within the plasticizing cylinder in the gas supply section, wherein the plasticizing cylinder is equipped with a multi-stage type screw comprising a front end side screw stage having screw flights wherein notches are formed in at least one of said screw flights and the gas and the molten resin are kneaded to dissolve the gas into the molten resin while part of the molten resin is caused to flow backward by means of said notches, and wherein the gas pressure in the gas space is kept at a predetermined level to control the gas dissolution amount.