Abstract Blow molded plastic containers where at least the body of such containers is of a laminated construction including, for example, a barrier layer which in the case of the container receiving carbonated products would be a gas barrier layer. It has been found that delamination does occur and this is now solved by selectively providing the container body with minute vent openings which do not extend entirely through the container body, but into that area where delamination occurs and there is an accumulation of a permeant, such as CO 2 . The minute vents may be formed in the exterior wall of the container either by way of piercing pins or by utilizing a laser. In the case of the piercing pins, there are incorporated in the blow mold for blow molding the container from a preform and are generally placed along the parting lines of the blow mold and also in central parts of the wall. The construction and operation of the piercing pins may be provided in several forms.
A method of forming a blow molded plastic container comprising the steps of providing a preform having at least a body portion of a laminated wall construction including an outer layer, a gas barrier layer and at least one inner layer including an inner most layer, blow molding the preform in a blow mold to form said container having an exterior, and forming at least one vent opening in the exterior of the container with the vent opening extending through the outer layer and the barrier layer only and not extending through the inner most layer.
Claim 2
Independent Claim
96 words
A method of forming a blow molded plastic container comprising the steps of providing a preform having at least a body portion of a laminated wall construction including an outer layer, a gas barrier layer and at least one inner layer including an inner most layer, blow molding the preform in a blow mold to form said container having an exterior, and forming at least one vent opening in the exterior of the container with the vent opening extending through the outer layer and the barrier layer only and not extending through the inner most layer.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein said vent opening is formed in the exterior of the container while the container is in said blow mold.
Claim 4
Dependent Claim
15 words
The method of claim 2 wherein said vent opening is formed by a piercing pin.
Claim 5
Dependent Claim
15 words
The method of claim 1 wherein said vent opening is formed by a piercing pin.
Claim 6
Dependent Claim
14 words
The method of claim 1 wherein said vent opening is formed by a laser.