1. Field of the Invention
The present invention relates to a method of making a plastic hollow article and, more particularly, to a method which is particularly suitable for making a can-shaped plastic hollow article such as a container having a molecularly oriented thin sidewall portion and a large ratio of the height to the diameter.
2. Description of the Prior Art
There is disclosed in U.S. Pat. No. 3,184,524 a method for producing a can-shaped plastic hollow article having a molecularly oriented sidewall portion with improved transparency, strength, and gas barrier. According to this method, the sidewall portion is formed by, at first, making a plastic preform by injection molding or the like, and then forcing the central portion of the preform into a mold cavity under pressure, while clamping the periphery of the preform and keeping the central portion at molecularly orientable temperature. This method, however, may be disadvantageous in that it requires a step to form the preform, it is difficult to prepare the preform from a laminate, and it is necessary to heat the preform uniformly to a molding temperature before it is forced into the mold cavity.
There is also disclosed in U.S. Pat. No. 4,122,147 a method for producing two-layer can-shaped plastic containers. However, this method is concerned with the melt molding which cannot be applied to the production of thin-walled plastic containers having the improved transparency and other properties resulting from molecular orientation.
USPTO Backgrounds
USPTO Backgrounds