HARD SHELL IN-MOLD CUP AND LABEL

Abstract

The claimed invention provides a method for molding a decorative cup with a hard exterior shell and a molded cup with a hard exterior shell such that the ink of the decoration and the adhesive are encapsulated between the molding material and the hard exterior shell.

Claims

1. A decorated injection molded container comprising: a polypropylene fusion layer; an image applied in ink to the polypropylene fusion layer; an adhesive layer applied to the image bearing polypropylene fusion layer; a clear rigid protective layer applied over the adhesive layer; an injection molded polypropylene layer, the injection molded polypropylene layer molding integrally with the image bearing fusion layer such that the adhesive layer and the ink of the image are encapsulated between the injection molded polypropylene layer and the rigid protective layer.

2. The decorated injection molded container of claim 1 wherein the clear rigid protective layer is polycarbonate.

3. The decorated injection molded container of claim 1 wherein the clear rigid protective layer is polyethylene terephthalate.

4. The decorated injection molded container of claim 1 wherein the clear rigid protective layer is between about 0.001 and 0.006 inches thick.

5. The decorated injection molded container of claim 1 wherein the polypropylene fusion layer is between about 0.0020 and 0.0026 inches thick.

6. A decorated injection molded container comprising: a clear rigid protective layer; an image applied to the clear protective layer; a polypropylene fusion layer; an adhesive layer applied to the image bearing polypropylene fusion layer, the adhesive layer operable to bond the polypropylene fusion layer to the image applied to the protective layer; an injection molded polypropylene layer, the injection molded polypropylene layer molding integrally with the fusion layer such that the adhesive layer and the ink of the image are encapsulated between the injection molded polypropylene layer and the rigid protective layer.

7. The decorated injection molded container of claim 6 wherein the clear rigid protective layer is polycarbonate.

8. The decorated injection molded container of claim 6 wherein the clear rigid protective layer is polyethylene terephthalate.

9. The decorated injection molded container of claim 6 wherein the clear rigid protective layer is between about 0.001 and 0.006 inches thick.

10. The decorated injection molded container of claim 6 wherein the polypropylene fusion layer is between about 0.0020 and 0.0026 inches thick.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a cross-sectional schematic drawing of a prior art in mold label molded into a plastic cup wherein the in mold label has been coated.

[0010] FIG. 1A is an enlarged cross-sectional view of FIG. 1.

[0011] FIG. 2 is a cross-sectional schematic drawing of a prior art in mold label molded into a plastic cup wherein the in mold label has been laminated.

[0012] FIG. 2A is an enlarged cross-sectional view of FIG. 2.

[0013] FIG. 3 is a cross-sectional schematic drawing of the claimed invention showing a hard shell protected ink in mold label molded into a cup.

[0014] FIG. 3A is an enlarged cross-sectional view of FIG. 3.

[0015] FIG. 4 is a drawing comparing the shrinkage of a 16 ounce heavy wall cup with a protected ink label and a 16 ounce heavy wall cup with a standard in-mold label. Although both cups are molded with the same polypropylene resin in the same amount, the in-mold label cup shrinks considerably more than the protected ink cup.

[0016] FIG. 5 is a production schematic for a protected ink label.

DETAILED DESCRIPTION

[0017] Now referring to the drawings in detail wherein like reference numerals refer to like elements throughout, FIGS. 3 and 3A show a cross-sectional schematic view of the claimed invention. As shown in more detail in FIG. 3A, hard shell material 11 comprises the outer section of the printed label. In one embodiment of the claimed invention, the hard surface layer 11 is printed with the label decoration resulting in an ink layer 13. A second embodiment provides for printing the thermally protective layer material.

[0018] Hard shell material 11 can be one of a number of possible materials including polycarbonate (PC) and polyethylene terephthalate (PETG). Primary considerations for hard shell 11 materials are price, heat softening and food safety. For these reasons, PETG is the currently preferred material for the hard shell 11. PETG is also preferable because it provides a very glossy appearance in comparison to other materials. PETG can also provide an alternative satin luster finish not currently available with other materials. Using PETG as an external protective layer protects the ink from degradation, making for longer lasting decoration, which is very important in the highly brand conscious souvenir cup industry. PETG is also BPA free, food safe and dishwasher safe.

[0019] Referring to FIG. 4, which shows that standard IML label cups shrink significantly as the molten polypropylene cools and hardens. Conventional IML labels are printed on a polypropylene substrate, which shrinks with the molten polypropylene as the molded cup cools. Thus, shrinkage is not a significant issue with standard in mold label cups. However, shrinkage is a significant problem in the claimed protected ink cups. The reason that shrinkage is a problem is that polypropylene used to mold the cups has a higher shrink rate than PETG, the material selected for the protected ink label. The shrinkage of the polypropylene relative to the PETG label requires that the PETG label have sufficient strength and rigidity to withstand the force caused by the shrinkage of the polypropylene molding material.

[0020] Referring back to FIGS. 3 and 3A, a molded container of the claimed invention comprises a hard shell material 11. Hard shell exterior ranges in thickness from between 0.002 inches to 0.008 inches. Most preferably, hard shell exterior is approximately 0.005 inches. As shown, hard shell material 11 also includes adhesive layer. The hard shell material 11 protects the ink layer 13, essentially sealing the ink layer 13 away from the surface of the cup. Ink layer 13 is printed onto primed polypropylene fusion layer 15 according to methods known in the art. Fusion layer 15 is polypropylene such that it bonds well with the polypropylene cup wall 17 during the molding process. Fusion layer is between approximately 0.0015 inches and 0.0031 inches thick. Most preferably, fusion layer is approximately 0.0023 inches thick. Adhesive laminate layer or fusion layer 15 provides high peak strength but is also sufficiently flexible to withstand the shearing force created by the shrinkage of the polypropylene molding material relative to the hard shell 11 material as the molded article cools. Finally, the edge cutting profile of the protected ink label helps relieve shearing force created by the shrinkage of the polypropylene molding material relative to the hard shell 11 material.

[0021] It is critical that the ink layer withstands the molding process and that it withstands the shear forces created between the label and the cup when the molten plastic cools, hardens and shrinks relative to the label. For this reason the PETG is either subsurface printed or surface printed using a fusion layer. Either treatment allows the ink to absorb higher shear forces.

[0022] Alternatively, as shown in the process diagram in FIG. 5, the claimed invention provides a process for printing the image directly on the thermally protective layer in a continuous process. Once the image is printed, adhesive is applied to the image downstream of the printing process. Following application of the adhesive layer, the rigid protective layer is applied via a lamination process. Upon completion of the lamination process, labels are die cut to size and inserted into the molding cavity whereupon molten plastic is injected to form a plastic cup.

[0023] The claimed process provides a new and unique method for molding a souvenir cup using a rigid outer shell to protect the ink layer. The claimed process and cup provides a cup structure wherein both the ink and the adhesive are within the wall of the molded cup, thus reducing the potential for exposure to either the ink or the adhesive. The claimed structure is significantly less susceptible to lamination peel than polypropylene laminated parts and ink migration. Additionally, the structure of the claimed invention is significantly less susceptible to deterioration from everyday use, including dishwasher cleaning and abrasion.

[0024] The present invention has been described in terms of embodiments. While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the invention.