WO1994004284A1

WO1994004284A1 - Process for coating a packaging surface

Info

Publication number: WO1994004284A1
Application number: PCT/US1993/007634
Authority: WO
Inventors: Arthur W. Robichaud; Michael S. Mabee
Original assignee: Combibloc, Inc.
Priority date: 1992-08-14
Filing date: 1993-08-13
Publication date: 1994-03-03
Also published as: EP0583727A1

Abstract

A method of applying various coatings, such as low density polyethylene (14, 20), oxygen scavenging resinous material (16), and anti-scalping resinous material (20), to a surface (12) of a food or beverage container (10). The coatings may be applied in a predetermined area using a printing process, brushing, spraying, or rolling. The container (10) may be a paperboard, gable top beverage container, or an aseptic paperboard container.

Description

PROCESS FOR COATING A PACKAGING SURFACE

BACKGROUND OF THE INVENTION

This invention relates generally to a process for use in the production of food and beverage packagings and, more particularly, to a process for applying various beneficial coatings in a predetermined manner onto food and beverage container surfaces.

It has been known for some time that contents of containers can interact with exposed surfaces of the container itself. The product contact surface of primary packages or containers may adsorb or absorb, i.e. scalp, essential oils and flavors from the product directly. Flavor transference (analogous to the reverse of scalping) can also occur in that the packaging material(s) can actually introduce an unwanted taste and/or odor into the product contents.

To attempt to lessen these adverse effects on product contents, efforts have been directed at adding an inner product contact layer to the packaging which is comprised of a material composition which tends not to scalp and/or which inhibits flavor transference. In multilayer paperboard packaging, these efforts have been limited to material layers that can be applied using traditional methods of packaging formation, such as extrusion and lamination processes in the paperboard packaging industry. There are certain problems associated with the current methods directed at solving these problems. First, the application of an additional functional layer to the laminate of the container is usually accomplished by the use of dedicated extrusion equipment making the application very capital intensive. Further, the additional layer(s) is applied across the entire packaging surface yet for this purpose it is really only needed on that portion of the surface which is in contact with the product contents. When applied on the entire surface it can interfere with other aspects of the packaging such as sealing capability.

Polyethylenes (e.g. - LDPE (low density polyethylene)) are commonly used in paperboard packaging as the innermost package layer because they are liquid tight and provide an effective matrix by which package seals are accomplished. Polyethylenes can scalp certain food and beverage flavors. Such scalping can in turn result in a modification of product flavor and shorten the shelf life of the product. Polyethylenes and other known product contact layers can also impart an undesirable flavor to the product contents.

Accordingly, there is a need for a new method of applying various beneficial material compositions onto a surface of a container, which is relatively inexpensive and which is capable of controlling the location of the composition on the packaging surface which will not interfere with the sealing surfaces of the package.

SUBSTITUTESHEET SUMMARY OF THE INVENTION The present invention provides a method of selectively coating a surface area of a food and/or beverage container with a material to achieve a desired effect. The coating material may be printed onto a surface (ordinarily, but not necessarily, the product contact or inner surface) of the packaging in a predetermined area and geometry to achieve the desired benefits without having the coating interfere with the sealing or other mechanics of the container. Further a coating may only be needed in a particular "zone" of the packaging surface such that different coatings may be applied to the same packaging in different zones (i.e.-on different areas of the same surface) .

The present invention is useful for coating surfaces of packagings comprising a paperboard substrate. However, packagings containing other substrate material are within the scope of this invention. Commonly, food and beverage packagings are extrusions of multiple material layers or laminations of various plastics onto a paperboard substrate to make the paperboard suitable for food and beverage containment. The packaging may typically be a multi-layered structure having a material such as LDPE, for example, as the innermost or product contact layer. The well known gable top milk cartons, aseptic beverage packages, and frozen food packagings are examples of these multi-layered structures.

SUBSTITUTESHEET It is an object of the present invention to provide a new method of applying a coating onto a packaging surface of aseptic packages and other composite paperboard packages.

Other objects and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a plan view of the inside surface of an unfolded food or beverage container which has been selectively coated using the process of the present invention;

Figure 2 is an enlarged, cross-sectional view of the structure of Figure 1;

Figure 3 is another embodiment of the present invention shown in an enlarged, cross-sectional view of the structure; and

Figure 4 is another embodiment of the present invention shown in an enlarged, cross-sectional view of the structure.

Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the detailed steps and the arrangement and selection of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it should be

SUBSTITUTESHEET understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S) The product contents may be affected by the inner surface of typical paperboard packages. Figure 1 is an example of an unfolded, pre-formed paperboard container which incorporates the present invention. Packages which contain products that include essential oils, for example, are well known in the art. A typical multi-layered container cross-section is illustrated in Figure 2 and is used herein for example purposes and is not to be construed to limit the invention to this structure. In Figure 2 the structure 10 includes a substrate 12 such as paperboard, an outer LDPE layer 14 applied to the outer surface of the substrate 12, an inner oxygen barrier layer 16 and an inner LDPE product contact layer 18 interior to the oxygen barrier layer 16.

For example, in order to prevent certain interactions of the packaging and its contents, a coating 20 may be applied to the inner product contact layer 18. Certain resinous materials are known to be resistant to scalping for example and could be used as the coating 20. In typical food and beverage paperboard packagings the product contact layer 18 has a sealing surface 22 and a non-sealing, product contact surface 24. The application of a particular coating 20 to

SUBSTI the sealing surface 22 of the product contact layer 18 could adversely affect the sealability performance of the container. Accordingly, with the method of the present invention, the coating 20 may be applied to the non-sealing surface 24 of the product contact layer 18.

In order to control the placement and location of the coating 20 onto the non-sealing surface 24 of the product contact layer 18 with a high degree of precision, the coating may be applied by well known printing processes such as rotogravure, offset or flexographic. The coating could also be applied to the product contact layer 18 by methods such as spraying, rolling or brushing while taking commonly known measures to maintain control of the precise area to be coated.

It merits recognition at this point that the method of the present invention may also be used to selectively coat the sealing surface 22 with a material that enhances sealing formation while preferably keeping this coating out of the non-sealing zone 24. Other zones of a package may also be selectively coated for other reasons. This demonstrates the versatility of the present invention.

Coatings for use with the present invention may be any of a number of materials known to have desirable characteristics, for example, enhanced sealing as described above, and improved resistance to bending and folding induced stress cracking. Other benefits may include resistance to scalping or flavor migration, and oxygen scavenging (since oxygen has negative effects on product quality and shelf life and it would be desirable to have such oxygen adsorbed into the packaging, thus precluding its reacting with the contents). For example, the coating may include, but is not limited to, polyesters, latex, PVDC's or other carrier resins capable of forming a suspension or emulsion which may be based in water or volatile solvent systems such as toluenes, acetates, alcohols and the like. The coating may be applied to the inner surface of the packaging material, in register, and cured in the same manner as printed graphics are to the outside surfaces of a package. The use of such solvent systems would facilitate the printing lay down technique since the behavior of these emulsions is similar to that of printing inks.

Another advantage of the present invention is that different types of coatings may be concurrently applied to different zones of a packaging surface to accomplish different objectives. This is done in much the same way as different colored inks are applied onto a package for obtaining a multi-colored packaging face. Examples of such embodiments of the present invention are shown in Figures 3 and 4. In Figure 3 coating C^ 30 and C2 40 may be applied to different zones of the package to accomplish separate objectives. For example, the coating Ci 30 may comprise a material composition that absorbs oxygen while coating C2 40

SUBSTITUTE HEET may offer improved resistance to stress cracking. The coatings 30 and 40πmay be applied using the same process as used to apply the coating 20 as described above. For example, in commonly known printing processes the positioning of the pattern for applying the coatings is controlled by the print registration control system known to those of ordinary skill in the art. The coatings may be applied using standard printing cylinders engraved with a predetermined pattern to lay the coating onto a continuously moving packaging material web. The positioning of the coating on the web is precisely controlled by print registration.

In Figure 4 coating C2 40 is shown being applied onto a portion of coating Ci 30. This embodiment is offered to demonstrate that the coatings may be applied in a juxtaposed relation or a stacked relation. In a stacked relation two or more coatings may interact in a particular beneficial way to provide a unique package characteristic(s) . Various features of the invention are set forth in the following claims.

SUBSTITUTE HE T

Claims

What is claimed is:

1. A method of making a food or beverage container, said method comprising the steps of: selecting a multi-layered composite structure having an inner surface including a sealing area and a product contact area; selecting a material coating to be applied to the product contact area, the material coating minimizing the chemical interaction between the container and the food or beverage thus maintaining the quality of the food or beverage contents; and applying the coating to the product contact area prior to sealing while maintaining the sealing area free of the coating.

2. The method of Claim 1 wherein the container is aseptic.

3. The method of Claim 1 wherein the coating is an anti-scalping resinous material.

4. The method of Claim 1 wherein the coating is an oxygen scavenging resinous material.

SUBSTIT 5. The method of Claim 1 wherein the coating is applied o the product contact surface by a printing process.

6. The method of Claim 5 wherein the printing process is rotogravure.

7. The method of Claim 5 wherein the printing process is offset.

8. The method of Claim 5 wherein the printing process is flexographic.

9. The method of Claim 1 wherein the coating is applied to the product contact surface by brushing.

10. The method of Claim 1 wherein the coating is applied to the product contact surface by spraying the coating onto the surface.

11. The method of Claim 1 wherein the coating is applied to the product contact surface by rolling the coating onto the surface.

12. The method of Claim 1 wherein the coating is a water based suspension. lS. The method of Claim 1 wherein the coating is a water based emulsion.

14. The method of Claim 1 wherein the coating is a solvent based emulsion.

15. The method of Claim 1 wherein the coating is a solvent based suspension.

16. The method of Claim 1 wherein the container is a gable top paperboard beverage container.

17. The method of Claim 1, further comprising: Applying a second coating to a zone of one of said areas of the container to inhibit a second form of interaction between the container and the food or beverage.

18. The method of Claim 17 wherein the second coating is applied to the zone of the product contact surface by a printing process.

19. A method for making a food or beverage container, said method comprising the steps of: selecting a material coating to be selectively applied to a sealing surface of the container, the material coating enhancing the sealing performance; and applying the coating to said sealing surface while maintaining other non-sealing zones of the container surface free of the coating.