Mitsui Petrochemical Industries, Ltd.

Mitsui Petrochemical Co., Ltd.

Takashi Satake

Hiroji Niimi

Kunio Tomita

A machine for molding a starting crystalline saturated polyester resin such as polyethylene terephthalate includes a device for first drying and then preheating the starting resin to a temperature above its melting point to lower the viscosity of the resin to such an extent that the resin is not substantially degraded in the compression section of the molding machine. A feed section is provided for quantitatively feeding the molten starting resin to the main body of the molding machine. Accordingly, the starting resin is molded into a desired shape in a molding machine under conditions such that the crystallization temperature of the resulting molded article is within 20.degree. C. of the crystallization temperature of the starting saturated crystalline polyester resin. By avoiding reductions in the crystallization temperature of the molded resin, the resin can be shaped by, for example, blow molding into a bottle or other configuration while satisfying simultaneously the requirements for transparency and dimensional stability. The molded polyester articles obtained using this molding apparatus are substantially free from chalking and variation in internal volume and are excellent in heat resistance.

Method for molding saturated crystalline polyesters and molding

A crystalline saturated polyester resin such as polyethylene terephthalate, is molded into a desired shape in a molding machine under conditions such that the crystallization temperature of the resulting molded article is within 20.degree. C. of the crystallization temperature of the starting saturated crystalline polyester resin. This is accomplished by preheating the resin in the molding apparatus to a temperature above its melting point to lower the viscosity of the resin to such an extent that the resin is not substantially degraded in the compression section of the molding machine. By avoiding reductions in the crystallization temperature of the molded resin, the resin can be shaped by, for example, blow molding into a bottle or other configuration while satisfying simultaneously the requirements for transparency and dimensional stability. The molded polyester articles obtained from the present invention are substantially free from chalking and variation in internal volume and are excellent in heat resistance.

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Kuga, Japan

Takashi Satake