BACKGROUND OF THE INVENTION
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
SUMMARY OF THE INVENTION
[0007] 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).
[0008] 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.
[0009] 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.
[0010] 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
[0011]
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.
[0012] 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 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)
[0013] 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.
[0014] 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 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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 C₁ 30 and
C₂ 40 may be applied to different zones of the package to accomplish separate objectives.
For example, the coating C₁ 30 may comprise a material composition that absorbs oxygen
while coating C₂ 40 may offer improved resistance to stress cracking. The coatings
30 and 40 may 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.
[0019] In Figure 4 coating C₂ 40 is shown being applied onto a portion of coating C₁ 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.
1. A method of making a food or beverage container, the container having a sealing surface
and a product contact surface, said method comprising the steps of:
selecting a material coating to be applied to the product contact surface, the
material coating having certain desirous effects on the quality of the container contents;
and
applying the coating to a predetermined zone of the product contact surface while
maintaining the sealing surface 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.
5. The method of Claim 1 wherein the coating is applied to 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.
13. 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 second predetermined zone of the container to accomplish
a second, additional desirous effect.
18. The method of Claim 17 wherein the second coating is applied to the second predetermined
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 surface of the container,
the material coating having certain desirous effects; and
applying the coating to a predetermined zone of the container surface while maintaining
other zones of the container surface free of the coating.