HEAT-SEAL FAILURE PREVENTION METHOD AND ARTICLE
A co-injected molded multi-layer article has inner and outer layers, an interior layer contained within the inner and outer layers and a surface portion to which a closure or other component may be heat-sealed. The article is molded by co-injecting the inner, outer and interior layer materials into a mold cavity of a mold. The interior layer material is caused to flow along a steam line offset from the zero velocity gradient of the combined material flow and biased toward a material flow for forming an outer wall of the multi-layer article. The resultant molded multi-layer article contains an interior layer located in a heat sealable region that avoids a breach or failure during a heat seal operation to seal an opening of the molded article.
1 . A co-injection molded multi-layer article comprising:
an inner layer including a first polymeric material;
an outer layer including the first polymeric material; and
an interior layer including a second polymeric material, the interior layer extending between the inner layer and the outer layer and biased toward a resulting outer wall surface of the multi-layer article to provide and maintain barrier or scavenger coverage in a heat sealable zone of the multi-layer article.
2 . The multi-layer article as defined in claim 1 , wherein a portion of the interior layer is folded over away from a heat seal contact surface in the heat sealable zone.
3 . The multi-layer article as defined in claim 1 , wherein a portion of the interior layer is folded over toward a resulting outer wall surface of the multi-layer article away from a heat seal contact surface in the heat sealable zone.
4 . The multi-layer article as defined in claim 1 , further comprising:
a cover heat-sealed to a heat seal contact surface in the heat sealable zone.
5 . The multi-layer article as defined in claim 1 , further comprising:
a flange having a heat seal contact surface in the heat sealable zone.
6 . The multi-layer article as defined in claim 1 , further comprising:
a heat seal contact surface in the heat sealable zone of the multi-layer article, the heat seal contact surface being substantially parallel to an orientation of the interior layer of the first polymeric material in the heat sealable zone.
7 - 20 . (canceled)
21 . The multi-layer article as defined in claim 4 , wherein 10% or more of a thickness of a flange in the heat sealable zone melts while the interior layer remains intact to maintain a barrier layer or a scavenger layer in the heat sealable zone of the multi-layered article.
22 . The multi-layer article as defined in claim 4 , wherein during the heat sealing operation 10% or more of a thickness of a flange in the heat sealable zone melts to form a gas impermeable bond between the cover and the multi-layer article.
23 . The multi-layer article as defined in claim 1 , wherein the first polymeric material and the second polymeric material are different materials.
24 . The multi-layer article as defined in claim 23 , wherein the first polymeric material is one of polyethylene terephthalate and polypropylene.
25 . The multi-layer article as defined in claim 24 , wherein the second polymeric material is ethylene vinyl alcohol.
26 . The multi-layer article as defined in claim 1 , wherein the interior layer is substantially gas-impermeable relative to a permeability of the inner layer and the outer layer.
27 . The multi-layer article as defined in claim 1 , wherein a fold over portion of the interior layer permits the interior layer to extend into a complete perimeter of the heat sealable zone and completely around a perimeter of a flange of the multi-layer article.
28 . The multi-layer article as defined in claim 27 , wherein the fold over portion of the interior layer is folded over away from a heat seal contact surface in the heat sealable zone.
29 . The multi-layer article as defined in claim 27 , wherein the fold over portion of the interior layer is folded over toward a resulting outer wall surface of the multi-layer article away from a heat seal contact surface in the heat sealable zone.