Matsushita Electric Industrial Co., Ltd.

Akio Ito

Masaaki Sunohara

Tooru Tamura

Shunsuke Matsuda

Hideaki Mochizuki

Yoshinobu Murakami

Yoshio Nakatani

Murakami Yoshinobu

Mitani Katsuaki

Toru Tamura

Tamura Tooru

A method of molding a plastic is initiated by injecting molten resin into a mold at a high pressure. The energy of the high pressure is partially stored in the form of elongation of tie bars of a molding machine. After the gate seals completely, the restoring force of the tie bars due to elastic deformation acts on the molded article as the mold article cools down. Each tie bar comprises a first member having a small modulus of elasticity and a second member. When the elongation of each tie bar is small, only the first member of small modulus of elasticity works. After the elongation reaches a certain amount of .DELTA.l.sub.1, the two members are connected parallel. As a result, the apparent modulus of elasticity of each tie bar increases rapidly. This makes it possible to mold a plastic with high dimensional accuracy.

Method of molding plastic and injection compression molding apparatus

There is provided an optical disc of high reliability, with the recording film protected from deterioration. The optical disc of this invention is produced by forming a tellurium suboxide film or optomagnetic recording film on a substrate made by injection molding from a polycarbonate resin. The substrate is made from a polycarbonate resin containing a phosphite ester-based antioxidant in a specific low amount.

Substrate for an optical disc

There are provided acrylic plastic lenses having a wide range of refractive indices as well as excellent physical and optical properties by polymerization of specific acrylic monomers in the presence of a photopolymerization initiator and a thermal polymerization catalyst.

Plastic lens of neopentyl glycol dimethacrylate copolymerized with

A heat cycle injection compression molding method comprises several steps: heating a synthetic resin until it becomes fluidized; injecting the fluidized synthetic resin into a large and nonuniform cavity formed by a cavity block and a mold which is slightly opened; cooling the injected fluidized resin until the center portion temperature of the resin is equal to or lower than a solidifying temperature of the resin, thereby solidifying the resin; reheating the solidified resin uniformly until the temperature of the resin is higher than the solidifying temperature, thereby making the resin fluidized again; compressing the refluidized resin by reducing the volume of the cavities; cooling the refluidized resin until the temperature of the refluidized resin is lower than a take-out set temperature, while continuing the compressing step, thereby resolidifying the resin; stopping the compressing step; and ejecting out of the mold a formed product having a large and nonuniform thickness.

Heat cycle injection compression molding method

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Katano, Japan

Akio Ito