| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem such as flatness, a shrink, a strain or a crack by fully filling a cavity with gas at a specific pressure, injecting a thermoplastic resin obtained by dissolving a specific value of carbon dioxide, starting compressing of a mold, fully filling the cavity with a resin, continuing the compressing, cooling and solidifying the resin. SOLUTION: A pressure of gas of a mold cavity is preferably 1 to 6 MPa. This means that a carbon dioxide absorbed to a thermoplastic resin may be larger than a pressure for foaming from a flow front. The carbon dioxide dissolved in the resin is preferably 0.3 to 2 wt.%. A vent hole 17 communicating with an exterior of the mold is opened at an outside of a movable side dowel 14, a gas tube 19 is attached to its outside, a carbon dioxide gas cylinder 20 is mounted at its end, and fully filled with the gas. A pressure release valve between the hole 17 and the tube 19 is set so as to release the pressure at 3 MPa or above, thereby preventing rising of the pressure in the cavity by the injected resin. |
