| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for stably molding an excellent optical molding having few weldline, optical strain and surface failure. SOLUTION: In the injection and compression molding method of a thermoplastic resin optical molding, firstly, the volume of a cavity is enlarged to be larger than that of an object optical molding. Secondly, a molten thermoplastic resin is filled through an injection cylinder in the cavity. Thirdly, after the resin pressure of the injection cylinder reaches the set value of 39 MPa or higher. Fourthly, then the enlarged cavity is compressed to the regular thickness of the molding. Fifthly, the excess thermoplastic resin caused by a pre- compression is sent back to the injection cylinder. Sixthly, the molten thermoplastic resin is held until an object molding is formed in the cavity. Lastly, the obtained molding is unloaded from the cavity.
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