Injection orientation blow molding method
AssigneeA. K. Technical Laboratory, Inc.
InventorSetsuyuki Takeuchi
Life of this patent
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Abstract
A molding method for continuously carrying out the steps from injection molding of a synthetic resin preform to orientation blow molding thereof into a thin-wall-hollow molded article, characterized in that releasing of the preform from the injection mold is carried out during the state where the shape thereof can be maintained by a skin layer produced at the surface by quick cooling and the state where internal cooling is not yet finished and the temperature is high, and orientation blow molding of the preform is carried out within a time till a surface temperature of the preform which rises by its own internal temperature reaches a peak temperature.
Claims16
An injection orientation blow molding method comprising the steps of:
- injecting and filling molten resin into an injection mold to form a preform;
- holding a mouth portion of said preform by a lip mold cooperating with said injection mold for forming said mouth portion;
- transferring a preform by said lip mold from the injection mold to a blow mold;
- and
- orientation blow molding the preform into a thin-wall hollow molded article, the method being characterized by further comprising:
- quick cooling the preform in said injection mold by an amount sufficient to form a skin layer on a surface of the preform which enables the preform to maintain its shape;
- removing the preform from the injection mold when an internal portion of the preform lying inward from the skin layer is at a higher temperature than the skin layer;
- and
- orientation blow molding the preform within a given time interval which terminates before a surface temperature of the preform, which rises due to the elevated internal temperature, reaches a predetermined peak temperature.
An injection orientation blow molding method comprising the steps of:
- quick cooling a preform made of a polyethylene terephthalate in an injection mold by an amount sufficient to form a skin layer on the surface of the preform engaging the injection mold, said skin layer enabling the preform to maintain its shape upon release of the preform from the mold;
- releasing the preform from the injection mold at a time such that, immediately after release from the injection mold, the temperature of the skin layer is above 60.degree. C. and below 70.degree. C. and an internal portion of the preform lying inward from the skin layer is at a higher temperature than the skin layer;
- and
- orientation blow molding the preform during a given time interval which terminates before the surface temperature of the preform reaches a peak temperature, and wherein said time interval starts when the surface temperature is above 80.degree. C. and terminates when the surface temperature is below 95.degree. C.
An injection orientation blow molding method comprising the steps of:
- making a preform of polypropylene in an injection mold;
- quick cooling the preform by an amount sufficient to form a skin layer on the surface of the preform engaging the injection mold, said skin layer enabling the preform to maintain its shape upon release of the preform from the mold;
- releasing the preform from said injection mold such that, immediately after release from the mold, the temperature of the skin layer is above 90.degree. C. and below 100.degree. C. and an internal portion of the preform lying inward from the skin layer is at a higher temperature than the skin layer;
- and
- orientation blow molding the preform during a time interval which begins when the surface temperature of the preform is above 100.degree. C. and which terminates when the surface temperature of the preform is below a peak temperature and is below 122.degree. C.
A method for injection orientation blow molding a thin walled hollow molded article comprising the steps of:
- (a) providing an injection mold for molding a preform and including a lip mold for forming a mouth portion and a body mold for forming the main body portion, said injection mold having cavity means designed to provide a preform of a predetermined configuration;
- (b) injecting molten resin into the injection mold cavity means;
- (c) holding the mouth portion of said preform by said lip mold which cooperates with the body mold to initially form the preform;
- (d) releasing the preform from the body mold;
- (e) transferring the preform from the injection mold towards a blow mold by means of said lip mold;
- (f) orientation blow molding the preform into a thin wall hollow molded article in said blow mold;
- said method being characterized by the step of quick cooling the preform after completing step (c) and before performing step (d) to control the temperature of said injection mold to form a skin layer to maintain the shape of the preform engaging said injection mold;
- step (d) further comprising releasing the preform therefrom during an interval which begins when an internal temperature of the preform is higher than the temperature of the skin layer and which ends before the temperature of the preform skin layer has reached a peak value;
- and
- blow molding the preform prior to the time that the temperature of the skin layer reaches said predetermined peak value.
Dependencies are inferred from the claim text.