Process for producing stretch blow formed plastic containers
AssigneeTetra Laval Holdings & Finance S.A.
InventorsElmar Mock, Lars Bergholtz
Life of this patent
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Abstract
Stretch blow molded containers are made from a preform made of a plastic material suitable for stretch blow molding such as, e.g., PET. The preform is heated to a temperature suitable for stretch blow molding and is introduced into a mold. An explosive gas mixture is introduced into the preform with a stretching pressure and the preform is axially stretched with the help of a stretching rod. After stretching, the explosive gas mixture is ignited, the explosion creating a blowing pressure which presses the wall of the preform against the inner wall of the mold so as to impart to the container its definite form. Due to the temperature shock generated by the explosion, the inner surface of the container is simultaneously sterilized.
Claims20
A method for the production of containers from a material for stretch blow molding comprising
- (a) heating a preform having a wall to a temperature for stretch blow molding,
- (b) introducing the resultant heated preform from step (a) into a mold having a cavity corresponding to a container to be molded, the preform having an inner wall,
- (c) creating a stretching pressure in the preform by introducing an explosive gas mixture into the preform,
- (d) stretching the preform axially with the aid of a stretching rod,
- (e) creating a blowing pressure higher than the stretching pressure in the resultant stretched preform by exploding the explosive gas mixture, and
- (f) pressing the wall of the preform against the inner wall of the mold to form the container.
Dependencies are inferred from the claim text.