Process for making multilayered containers
AssigneeNational Can Corporation
InventorDonald G. Sauer
Life of this patent
Estimating the term…
Abstract
A process for forming a hollow multilayered thermoplastic article utilizing a liner and a core rod formed at least in part of a porous metal and having a blow slot. A vacuum is applied to the liner through the porous metal part of the core rod and optionally the blow slot and blowing pressure is applied through the blow slot.
Claims15
A process for forming a hollow multilayered thermoplastic article, comprising the steps of:
- (A) placing a previously formed liner comprised of a thermoplastic material over a blow slot equipped core rod having liner engaging exterior surface portions formed at least in part of a porous material having a porosity of from about 1/2 to 5 microns, said liner having an internal surface configuration which is generally conformable with said exterior surface portions, said exterior surface portions being removable from said thermoplastic material,
- (B) reducing the pressure within said liner equipped core rod below ambient at said porous portions and optionally at said blow slot, the interrelationship between said liner and said surface portions occupied by said porous portions and said blow slot if open being such that an intimate substantially gas free contact between said liner and said adjacent exterior surface portions is achieved,
- (C) maintaining a reduced pressure within said core rod while providing an injection mold adjacent said liner on said core rod,
- (D) injecting an injectable heated thermoplastic resin into said injection mold over said liner to form a composite preform with said liner while maintaining a reduced pressure within said core rod,
- (E) removing said preform on said core rod from said cavity,
- (F) providing a blow mold adjacent said preform while maintaining said preform in a blow-moldable state,
- (G) pressurizing the interior of said preform substantially through said blow slot to an extent sufficient to make portions of said preform expand against said blow mold, thereby to produce a blown container.
In a process for forming a hollow multilayered article comprising the steps of positioning a previously formed liner of a thermoplastic material over a core rod, said core rod having an outer surface, a hollow interior, and a blow opening communicating said hollow interior with that portion of said outer surface of said core rod over which said liner is positioned, said liner having an internal surface configuration which is generally conformable with said outer surface of said core rod over which said liner is positioned, injecting a thermoplastic resin layer over said liner, blow molding said article by pressurizing said liner with said resin layer thereon through said hollow interior and said blow opening to expand said liner and said resin layer to form a container, and removing said article from said core rod, the improvement comprising the step of evacuating the air in the space between said outer surface of said core rod and the adjacent inner surface of said liner through a porous metal section on said core rod and also optionally at said blow opening, said evacuation step occurring before said injecting step, said porous metal section having a porosity of from about 1/2 to 5 microns, thereby to achieve substantially gas free contact between said liner and said core rod.
Dependencies are inferred from the claim text.