MULTILAYER CONTAINER TRIMMING
A method making a plastic container in accordance with one aspect of the present invention includes molding an intermediate container product having a body and a moil integral with the body. The body is of layered construction that includes at least one layer of barrier resin that extends part-way into but not throughout the moil. The upper portion of the moil, in which the barrier material is absent, is removed for recycling as process regrind. The lower portion of the moil is removed to form the container. In the preferred embodiment of the invention, the upper portion of the moil is removed in a laser trimming operation. The lower portion of the moil is removed in the preferred embodiment of the invention by inserting a plug into the open end or mouth of the container, and employing a cutting tool that is positioned by the plug for accurately trimming of the container product with respect to the mouth of the container. The cutting tool preferably is either a pair of shear rollers or a laser cutting tool.
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The present invention relates to fabrication of multilayer plastic containers, and more particularly to removal of a moil or dome from the container after blow molding.
BACKGROUND AND SUMMARY OF THE INVENTIONIn the fabrication of certain types of containers, particularly wide-mouth containers, it is conventional practice to blow mold an intermediate container product from a preform, and then to remove the upper portion of the intermediate product, referred to as a dome or moil, in a post-molding operation. U.S. Pat. No. 4,576,843 discloses a container manufacturing method of this type, in which the moil is removed by knife blades carried by the blow mold sections. It has also been proposed to fabricate containers of the subject type having a multilayer or laminated sidewall that includes one or more intermediate layers of barrier resin such as ethylene vinyl alcohol (EVOH) or nylon. U.S. Pat. No. 4,550,043, for example, discloses a process for making a preform for such a container, in which the intermediate barrier layer can be controlled to extend only part-way through the preform and the intermediate container product.
Problems are encountered when making containers of this type. For example, it is difficult to control placement of the edge of the intermediate barrier layer exactly at the moil trim line, so that the barrier layer must be made to extend into the moil to ensure that the barrier layer extends throughout the final container product. This, however, compromises the ability to use the trimmed moil as process regrind inasmuch as it is undesirable to have barrier material in the process regrind. Furthermore, the use of knife blades to trim a multilayer container product is undesirable because the blade can cause delamination at the trim line, and because the knife blade is subject to excessive wear when used in combination with abrasive container layer materials such as polyethylene terephthalate (PET). U.S. Pat. No. 4,549,066 discloses the use of a laser for performing the trimming operation, which reduces the delamination and wear problems.
A method making a plastic container in accordance with one aspect of the present invention includes molding an intermediate container product having a body and a moil integral with the body. The body is of layered construction that includes at least one layer of barrier resin that extends part-way into but not throughout the moil. The upper portion of the moil, in which the barrier material is absent, is removed for recycling as process regrind. The lower portion of the moil is removed to form the container. In the preferred embodiment of the invention, the upper portion of the moil is removed in a laser trimming operation. The lower portion of the moil is removed in the preferred embodiment of the invention by inserting a plug into the open end or mouth of the container, and employing a cutting tool that is positioned by the plug for accurately trimming the container product with respect to the mouth of the container. The cutting tool preferably is either a pair of shear rollers or a laser cutting tool.
The invention, together with additional objects, features, advantages and aspects thereof, will be best understood from the following description, the appended claims and the accompanying drawings, in which:
Container 12 is formed from a blow molded intermediate container product 24 (
The container intermediate product 24 is then subjected to a second trimming operation, which is illustrated schematically in
There have thus been disclosed a method of making a plastic container, and a resulting container, that fully embody all of the objects and features discussed above. The invention has been disclosed in conjunction with an exemplary presently preferred embodiment thereof, and a number of modifications and variations have been discussed. Other modifications and variations will readily suggest themselves to persons of ordinary skill in the art. The invention is intended to embrace all such modifications and variations as fall within the spirit and broad scope of the appended claims.
Claims
1-14. (canceled)
15. A plastic container made in accordance with a method which includes the steps of:
- (a) molding an intermediate plastic container product having a body and a moil integral with the body, the body being layered and including at least one layer of barrier material that extends part-way into but not throughout the moil;
- (b) removing an upper portion of the moil in which the barrier material is absent; and
- (c) removing, from the remaining moil integral with the body, a lower portion of the moil in which the barrier material is present, to form the container.
16. The container of claim 15, wherein the upper moil portion is removed with a laser.
17. The container of claim 15, wherein a plug is inserted into an open mouth of the container product after removal of the upper moil portion.
18. The container of claim 17, wherein a tool is positioned with respect to the plug for removing the lower moil portion.
19. The container of claim 18, wherein the tool comprises shear rollers or a laser.
20. The container of claim 15, wherein the removal of the upper moil portion maximizes the extent of the barrier layer in the lower moil portion.
21. The container of claim 15, wherein following removal of the upper and lower moil portions there is provided a radially outwardly extending flange at an open mouth of the container.
22. The container of claim 21, including securing a lid to the flange.
23. The container of claim 22, wherein the securing is by double-seam crimping of the lid to the flange.
24. The container of claim 21, wherein a radial outer edge of the flange is trimmed.
25. The container of claim 24, wherein the outer edge of the flange is cut on a circle located with respect to an axis of the open mouth of the container.
26. The container of claim 21, wherein a plug is inserted into an open end of the container product after removal of the upper moil portion, and the flange is trimmed on a circle located with respect to an axis of the plug and open end of the container product.
27. The container of claim 21, wherein the barrier layer extends to a radially outer edge of the flange.
28. The container of claim 15, wherein the upper moil portion is recycled.
29. The container of claim 15, wherein the lower moil portion is processed as regrind.
30. The container of claim 15, wherein the layers include at least one layer of polyethylene teraphthalate (PET).
31. The container of claim 30, wherein the layers include inner and outer layers of PET.
32. The container of claim 30, wherein the barrier material is EVOH or nylon.
33. The container of claim 30, wherein the layers include the barrier layer between inner and outer layers of PET.
34. The container of claim 30, wherein the layers include five layers in the form PET/barrier/PET/barrier/PET.
35. A plastic container made in accordance with a method which includes the steps of:
- (a) blow molding an intermediate container product having a body and a moil integral with the body, the body being layered and including at least one intermediate layer of barrier material that extends part-way into but not throughout the moil,
- (b) removing an upper portion of the moil, in which the barrier material is absent, in a laser cutting operation, and
- (c) removing, from the remaining moil integral with the body, a lower portion of the moil, in which the barrier material is present, to form the container, wherein step (c) includes inserting a plug into an open end of the container and severing the lower portion of the moil with a cutting tool positioned by the plug.
36. The container of claim 35, wherein the cutting tool comprises shear rollers or a laser.
37. The container of claim 35, wherein the removal of the upper moil portion maximizes the extent of the barrier layer in the lower moil portion.
38. The container of claim 35, wherein following removal of the upper and lower moil portions there is provided a radially outwardly extending flange at an open mouth of the container.
39. The container of claim 38, including securing a lid to the flange.
40. The container of claim 38, wherein a radial outer edge of the flange is trimmed.
41. The container of claim 40, wherein the outer edge of the flange is cut on a circle located with respect to an axis of the open mouth of the container.
42. The container of claim 38, wherein the barrier layer extends to a radially outer edge of the flange.
Type: Application
Filed: Jan 26, 2009
Publication Date: May 21, 2009
Applicant: Graham Packaging PET Technologies Inc. (York, PA)
Inventors: THOMAS E. NAHILL (Amherst, NH), David P. Piccioli (Auburn, NH)
Application Number: 12/359,753
International Classification: B65D 90/02 (20060101);