Non-symmetric multiple layer injection molded products and methods
View Patent ↗A mold for molding an injection molded article comprises a mold cavity with a non-symmetrical portion. At least one flow leader in the non-symmetrical portion of the cavity produces a symmetrical flow boundary in a multilayer flow downstream of the non-symmetrical portion of the mold cavity. The at least one flow leader may be a variable thickness flow leader or may alternatively be a plurality of flow leaders having a flow path length that differs from the flow path length of an adjacent flow leader by no more than about 15%. The multilayer flow comprising an inner layer, an outer layer, and an interior layer. Co-injection molding apparatus and methods that may use the foregoing mold are disclosed. Similarly, co-injection molded articles and containers that may result from the foregoing mold, apparatus, and methods are disclosed.
1. A multiple layer injection molded article comprising:
(a) at least one first material generally defining a configuration of the molded article including:
a closed end opposite an open end;
a non-symmetric shape relative to rotation about an axis extending through the center of the closed end and the center of the open end; and
a plurality of article portions defined by a plurality of flow leaders, each of the plurality of article portions adjacent to at least one other article portion in the plurality of article portions, and for each of the plurality of article portions:
a thickness of a selected article portion at a first distance from the center of the closed end, as measured along a midline of a radial cross-section taken through the center of the selected article portion, is different from a thickness of an adjacent article portion at the first distance from the center of the closed end, as measured along a midline of a radial cross-section taken through the center of the adjacent article portion; and
a length of the selected article portion, as measured from the center of the closed end to the periphery of the article along the midline of the radial cross-section of the article taken through the center of the selected article portion, differs from a corresponding length of any adjacent article portion by no more than about 15%; and
(b) at least one second material substantially contained within the at least one first material and extending throughout more than 95 percent of the entire molded article.
2. The multiple layer injection molded article of claim 1 wherein the at least one first material comprises a plastic material including at least one of polyethylene and polypropylene.
3. The multiple layer injection molded article of claim 1 wherein the at least one first material and at least one second material comprise different materials.
4. The multiple layer injection molded article of claim 1 wherein the at least one second material is relatively more gas impermeable than the at least one first material.
5. The multiple layer injection molded article of claim 1 wherein the at least one second material comprises at least one of ethyl vinyl alcohol, nylon, an oxygen scavenging material, and a desiccant.
6. The multiple layer injection molded article of claim 1 wherein one of the at least one first material and the at least one second material comprises an adhesive.
7. The multiple layer injection molded article of claim 1 wherein the at least one second material extends throughout at least about 99% of the molded article.
8. The multiple layer injection molded article of claim 1 wherein at least a portion of the at least one second material is folded over within the at least one first material.
9. The multiple layer injection molded article of claim 1 , wherein for each of the plurality of article portions, the length of the selected article portion differs from the corresponding length of any adjacent article portion by no more than about 10%.
10. The multiple layer injection molded article of claim 9 , for each of the plurality of article portions, the length of the selected article portion differs from the corresponding length of any adjacent article portion by no more than about 5%.