Heat-seal failure prevention apparatus
View Patent ↗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 molding apparatus comprising a mold defining a mold cavity, the molding apparatus comprising:
a nozzle assembly configured to inject a first polymeric material into a mold cavity configured to form an interior layer of a resulting multi-layer article and to inject a second polymeric material into the mold cavity to form an inner layer and an outer layer of the resulting multi-layer article; and
a processor programmed to execute instructions to position a flow of the first polymeric material in a heat sealable zone of the resulting multi-layer article to avoid a failure in the resulting multi-layer article when the heat sealable zone melts during a heat sealing operation by co-injecting the first polymeric material into the mold cavity along a flow line offset from a zero-velocity gradient of a combined flow of the first and second polymeric materials, and
wherein the processor is further programmed to execute instructions to cause the first polymeric material to fold over in the heat sealable zone away from a heat seal contact surface.
2. A co-injection molding apparatus as defined in claim 1 , wherein the failure is a breach in the integrity of the layers of the resulting multi-layer article.
3. A co-injection molding apparatus as defined in claim 2 , wherein the breach in the integrity of the layers damages the performance of the resulting multi-layer article.
4. A co-injection molding apparatus as defined in claim 1 , wherein the failure is a breach in the integrity of a heat sealable portion of the resulting multi-layer article.
5. A co-injection molding apparatus as defined in claim 1 , wherein the processor is further programmed to execute instructions to maintain the flow line of the first polymeric material offset from the zero-velocity gradient of the combined flow throughout co-injection of the first polymeric material into the mold cavity.
6. A co-injection molding apparatus as defined in claim 1 , wherein the processor is further programmed to execute instructions to co-inject the first polymeric material along a flow line biased toward a resulting outer wall surface of the resulting multi-laver article.
7. A co-injection molding apparatus as defined in claim 1 , wherein the processor is further programmed to execute instructions to maintain the flow line of the first polymeric material along a flow line biased toward a resulting outer wall surface of the resulting multi-layer article.
8. A co-injection molding apparatus as defined in claim 7 , wherein the flow line offset is selected based on a location of a heat sealable surface in the heat sealable zone of the resulting multi-layer article.
9. A co-injection molding apparatus as defined in claim 1 , wherein the resulting multi-layer article includes an open end opposed to a closed end, and a flange disposed at the open end with the flange including the heat sealable zone.
10. A co-injection molding apparatus as defined in claim 1 , wherein the heat sealable zone of the resulting multi-layer article includes a sealable surface substantially parallel to an orientation of the interior layer of the first polymeric material in the heat sealable zone of the resulting multi-layer article.