Note: Descriptions are shown in the official language in which they were submitted.
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PACKAGING MATERIAL FOR FOOD ITEMS
CONTAINING PERMEATING OILS
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application No.
60/695,145, filed June 29, 2005, the disclosure of which is incorporated by
reference herein in its entirety.
TECHNICAL FIELD
The present invention relates generally to packaging materials and, more
particularly, relates to packaging materials for food items containing a
permeating oil.
BACKGROUND
Paper-based bags and cartons frequently are used to package frozen food
items, such as French fries, hash browns, and breaded chicken. However, such
products often are coated with oils that are capable of permeating the paper
or
paperboard. When oils penetrate the packaging, a darkened area or stain
appears on the outside of the carton. Such staining detracts from the
appearance of the packaging, which may be viewed as damaged or
contaminated.
Recently, interest in low or non-trans fatty acid oils has increased
because these oils are viewed as healthier than other oils. However, unlike
other oils, which freeze at typical freezer temperatures, the non- or low
trans
fatty acid oils remain fluid, thereby causing greater staining to the package.
Thus, there remains a need for packages and packaging materials that prevent
staining by oils, mask staining by oils, or any combination thereof.
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SUMMARY
Various aspects of the present invention relate generally to a packaging
material for oily or greasy food items, and methods of making such packaging
materials. The various packaging materials include features for resisting
penetration, masking penetration, or for both resisting and masking
penetration
by one or more oily or greasy substances (hereinafter "oil" or "oils")
associated
with some food items.
According to one aspect, the present invention relates to an oil resistant
packaging material comprising a substrate that is susceptible to discoloration
by an oil, and an oil resistant layer substantially overlying the substrate,
where
the oil resistant layer comprises a polymer that is substantially resistant to
penetration by oil. The oil resistant layer may have any suitable basis
weight,
for example, from about 1 to about 10 lbs/ream (3000 sq. ft.), or from about 2
to about 6 lbs/ream.
The oil resistant layer may comprise a single polymer, for example,
polypropylene, or may comprise a blend of two or more polymers. In one
example, the oil resistant layer comprises from about 50 to about 99 wt %
polypropylene and up to about 50 weight (wt) % low density polyethylene,
propylene-ethylene copolymer, polyethylene terephthalate, nylon 6,6,
polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, or any
combination thereof. If desired, the oil resistant layer may include a filler.
In
one example, the oil resistant layer may include from 0 to about 30 wt %
filler.
In another example, the packaging material includes a substrate comprising
paper or paperboard, and an oil resistant layer comprising polypropylene and a
filler selected from the group consisting of calcium carbonate, magnesium
carbonate, silica, calcium oxide, alumina, titanium dioxide, or any
combination
thereof.
In one variation of this aspect, the packaging material includes a heat
seal layer substantially overlying the oil resistant layer. The heat seal
layer
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may be, for example, a thermoplastic polymer having a softening temperature
of from about 180 F to about 380 F. Thus, for example, the present invention
contemplates a packaging material in which the substrate comprises paper or
paperboard, the oil resistant layer comprises polypropylene, and the heat seal
layer comprises low density polyethylene.
According to another aspect of the invention, a packaging material for a
food item containing an oil comprises a substrate that is susceptible to
discoloration by an oil, a tie layer substantially overlying the substrate, an
oil
resistant layer substantially overlying the tie layer, and a heat seal layer
substantially overlying the oil resistant layer. The oil resistant layer
comprises
a polymer that is substantially resistant to penetration by oil.
Each of the various layers may be formed from numerous materials, and
one or more layers may be formed from different polymers or the same
polymers. In one example, the tie layer and the heat seal layer are formed
from
the same polymer. In another example, the tie layer and the heat seal layer
are
formed from different polymers. In one particular example, the substrate
comprises paper or paperboard, the tie layer comprises low density
polyethylene, the oil resistant layer comprises polypropylene, and the heat
seal
layer comprises low density polyethylene.
Furthermore, the various layers may be present in any suitable amount.
In one particular example, the paper or paperboard has a basis weight of from
about 8 to about 2501bs/ream, the tie layer has a basis weight of from about
0.1
to about 5 lbs/ream, the oil resistant layer has a basis weight of from about
0.1
to about 20 lbs/ream, and the heat seal layer has a basis weight of from about
1
to about 15 lbs/ream.
According to yet another aspect of the invention, a packaging material
for masking staining by an oil comprises a substrate that tends to absorb
oils,
and at least one of an (1) opacity modifying additive and (2) a plurality of
bleached fibers incorporated into the substrate. In one example, the opacity
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modifying additive comprises a white pigment, such as titanium dioxide. In
another example, the substrate is formed from a plurality of fibers, where at
least about 10 wt % of the fibers are bleached fibers. In one particular
example, the substrate comprises paper having a basis weight of from about 30
to about 50 lbs/ream, including at least about 25 wt % bleached fiber, and the
opacity modifying additive comprises at least about 90 lbs of titanium dioxide
per ton of paper. In another particular example, the substrate comprises paper
having a basis weight of from about 30 to about 50 lbs/ream, including at
least
about 50 wt % bleached fiber, and the opacity modifying additive comprises at
least about 180 lbs of titanium dioxide per ton of paper.
According to still another aspect of the invention, a packaging material
for masking staining by an oil comprises a substrate that tends to absorb
oils,
and an opacity modifying layer substantially overlying the substrate, where
the
opacity modifying layer comprises a polymer and an opacity modifying
additive. In one example, the opacity modifying additive comprises titanium
dioxide. In one variation of this aspect, the packaging material includes a
tie
layer positioned between the substrate and the opacity modifying additive
layer. In another variation of this aspect, the packaging material includes a
heat seal layer substantially overlying the opacity modifying layer distal the
substrate. The various layers may be formed from any suitable material
including, but not limited to, those described herein.
According to yet another aspect of the invention, a packaging material
for masking staining by an oil comprises a substrate that tends to absorb
oils,
thereby creating a stain, and a stain masking layer overlying at least a
portion
of the substrate. The stain masking layer comprises a colorant that closely
resembles the color of the stain, obscures the glossiness of the stain, is
sufficiently opaque to conceal the stain, or any combination thereof. In one
example, the colorant comprises a dark, non-reflective pigment that closely
resembles the color of the stain, for example, a grey or black pigment. In
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another example, the colorant comprises a reflective pigment that obscures the
glossiness of the stain, for example, aluminum flake, brass flake, a
pearlescent
pigment, or any combination thereof. In still another example, the colorant
comprises a first, dark, non-reflective pigment that closely resembles the
color
of the stain, and a second, reflective pigment that obscures the glossiness of
the
stain. In one example, the colorant comprises from about 50 to about 99 wt %
carbon black and from about 1 to about 50 wt % aluminum flake.
Various configurations of the stain masking layer are contemplated
hereby. In one example, the stain masking layer overlies at least a portion of
the substrate in a substantially continuous or solid configuration. In another
example, the stain masking layer overlies at least a portion of the substrate
in a
patterned configuration. Thus, in one particular example, the colorant
comprises carbon black and the stain masking layer overlies at least a portion
of the substrate in a patterned configuration comprising lighter and darker
shades of black.
In one variation, an opacity modifying additive, a plurality of bleached
fibers, or any combination thereof may be incorporated into the substrate. In
one example, the opacity modifying additive comprises titanium dioxide.
In another variation, the stain masking layer overlies at least a portion of
a first side of the substrate, and the packaging material further comprises an
opacity modifying layer overlying at least a portion of a second side of the
substrate. In one example, the opacity modifying layer comprises a polymer
and an opacity modifying additive, for example, titanium dioxide. Optionally,
a tie layer may be positioned between the substrate and the opacity modifying
layer.
According to still a further aspect of the invention, a packaging material
for a food item containing an oil comprises a paper-based substrate that
appears
to be stained when brought into contact with an oil, a tie layer substantially
overlying a first side of the substrate, an oil resistant layer substantially
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overlying the tie layer, a heat seal layer substantially overlying the oil
resistant
layer, and a stain masking layer overlying at least a portion of a second side
of
the substrate. The oil resistant layer may comprise a polymer that is
substantially resistant to penetration by oil and an opacity modifying
additive.
The stain masking layer may comprise a colorant that closely resembles the
color of the stain, obscures the glossiness of the stain, or any combination
thereof. The colorant may comprise a first, dark, non-reflective pigment that
closely resembles the color of the stain, and a second, reflective pigment
that
obscures the glossiness of the stain. In one variation, the colorant comprises
from about 60 to about 80 wt % carbon black, and from about 20 to about 40
wt % aluminum flake.
In one variation, the tie layer comprises low density polyethylene, the
polymer in the oil resistant layer comprises polypropylene, the opacity
modifying additive comprises titanium dioxide, and the heat seal layer
comprises low density polyethylene.
In another variation, the paper-based substrate has a basis weight of
from about 8 to about 250 lbs/ream, the tie layer has a basis weight of from
about 0.1 to about 5 lbs/ream, the oil resistant layer has a basis weight of
from
about 0.11 to about 20 lbs/ream, and the heat seal layer has a basis weight of
from about 1 to about 15 lbs/ream.
Any of the various materials may be used to form a package, for
example, for a food item containing an oily substance. In one particular
example, any of the various materials may be used to form a conventional bag
or other package for potato-based food items, such as French fries.
Other aspects and features of the present invention will become apparent
in view of the figures and the following description.
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BRIEF DESCRIPTION OF THE DRAWINGS
The description refers to the accompanying drawings, some of which are
schematic, in which like reference characters refer to like parts throughout
the
several views, and in which:
FIG. 1 schematically depicts a cross-sectional view of an exemplary
packaging material according to various aspects of the present invention;
FIG. 2 schematically depicts a cross-sectional view of another
exemplary packaging material according to various aspects of the present
invention;
FIG. 3A schematically depicts a cross-sectional view of yet another
exemplary packaging material according to various aspects of the present
invention;
FIG. 3B schematically depicts an exemplary process for forming the
material of FIG. 3A;
FIG. 4A schematically depicts a cross-sectional view of still another
exemplary packaging material according to various aspects of the present
invention; and
FIG. 4B schematically depicts an exemplary process for forming the
material of FIG. 4A.
DESCRIPTION
Various aspects of the present invention relate generally to a material for
packaging a food item. More particularly, various aspects of the present
invention relate generally to a material for packaging a food item that is
coated
with or contains an oily or greasy substance, for example, a trans fatty acid
oil,
a low trans fatty acid oil, a non-trans fatty acid oil, a saturated oil, an
unsaturated oil, grease, or butter (collectively "oil" or "oils"), that
potentially
can penetrate one or more components of the packaging material. The
packaging material of the present invention includes features for resisting
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penetration, niasking penetration, or for both resisting and masking oil
penetration. It will be understood that any combination of the techniques and
features disclosed herein or contemplated hereby may be used alone or in any
combination as needed or desired.
Any of the numerous packaging materials described herein or
contemplated hereby may be used to form bags, cartons, carton blanlcs, or
other
constructs for containing a food item therein. In one example, the packaging
material is used to form a bag for containing a potato-based food item such as
hash browns, French fries, or the like.
Oil Resistant Materials
According to one aspect of the present invention, a packaging material
includes features that render the packaging material oil resistant, although
it
includes one or more components or layers that are otherwise susceptible to
oil
penetration. For example, the packaging material may include an oil
permeable substrate coated with one or more additional layers that resist
penetration by oil.
Various aspects of the invention may be illustrated by referring to the
figures, which depict numerous examples of packaging materials and schematic
processes for forming such materials. For purposes of simplicity, like
numerals
may be used to describe like features. It will be understood that where a
plurality of similar features are depicted, not all of such features
necessarily are
labeled on each figure. Although several different exemplary aspects,
implementations, and embodiments of the various inventions are provided,
numerous interrelationships between, combinations thereof, and modifications
of the various inventions, aspects, implementations, and embodiments of the
inventions are contemplated hereby.
FIG. 1 depicts a schematic cross-sectional view of an exemplary
packaging material 100 according to various aspects of the invention. The
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packaging material 100 may include a substrate 105, and an oil resistant layer
110 substantially covering or overlying the substrate 105.
The substrate 105 may be a material that is susceptible to penetration by
oil, for example, a paper or paperboard. In this and other aspects of the
present
invention, the paper or paperboard may be, for example, a bleached or
unbleached Kraft paper, or may be a paper formed from a blend of natural
Kraft unbleached fibers and bleached fibers. However, it will be understood
that although paper-based substrates are described in detail herein, the oil
resistant features described herein are applicable to any other type of
substrate
which is permeable to oil and, thus, subject to undesirable staining.
The oil resistant layer 110 may be formed from one or more materials
that resist penetration by oil. In one aspect, the oil resistant layer is a
resin,
polymeric material, or film, for example, polypropylene, including various
metallocene polypropylenes, polyethylene, including low density polyethylene,
propylene-ethylene copolymers, including random propylene-ethylene
copolymers, polyethylene terephthalate, nylon 6,6, polyvinylidene chloride,
polyvinyl alcohol, ethylene vinyl alcohol, or any combination thereof. One
example of a polypropylene that may be suitable for use with the present
invention is available commercially from Chevron Phillips (Kingsport,
Tennessee) under the trade name MARLEX . One example of a polyethylene
terephthalate that may be suitable for use with the present invention is
available
commercially from Toray Plastics (America), Inc. (Front Royal, Virginia)
under the trade name PA10. One example of a polyvinyl alcohol that may be
suitable for use with the present invention is available commercially from
DuPont (Wilmington, Delaware) under the trade name ELVANOL . One
example of a polyvinylidene chloride that may be suitable for use with the
present invention is available commercially from Dow Chemical Company
(Midland, Michigan) under the trade name SARAN . One example of an
ethylene vinyl alcohol that may be suitable for use with the present invention
is
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available commercially from Evalco (Houston, Texas) under the trade name
EVAL Resins. Another polymeric material that may be suitable is SURLYN ,
a blend of ethylene/methacrylic acid copolymers commercially available from
DuPont (Wilmington, Delaware). Other materials are contemplated hereby.
The oil resistant layer may include various other additives and
components as desired. The other additives and components may be selected
to iinprove adhesion to the paper substrate or to other layers or components
within the packaging material, may increase resistance to oil permeation, or
may provide other functions or attributes. For example, the polypropylene may
be blended with other polymers, for example, thermoplastic polymers. In one
particular example, the polypropylene is blended with polyethylene, for
example, low density polyethylene. In another example, the polypropylene is
blended with an organic or inorganic filler, for example, calcium carbonate,
magnesium carbonate, silica, calcium oxide, alumina, titanium dioxide, any
other filler, or any mixture thereof. In still another example, the
polypropylene
is blended with low density polyethylene and calcium carbonate. While such
examples are provided herein, numerous other additives and components are
contemplated hereby. It will be understood that some of such fillers,
additives,
and components also may alter other characteristics, for example, the opacity,
of one or more layers and/or the packaging material in its entirety.
When the oil resistant layer includes more than one polymer or other
additive, each of the various components may have a weight percent greater
than 0 up to 100 wt %. Thus, in each of various examples, the oil resistant
layer independently may include from about 50 up to 100 wt % polypropylene
and from 0 to about 50 wt % low density polyethylene, from about 60 to 100
wt % polypropylene and from 0 to about 40 wt % low density polyethylene,
from about 70 to 100 wt % polypropylene and from 0 to about 30 wt % low
density polyethylene, from about 80 to 100 wt % polypropylene and from 0 to
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about 20 wt % low density polyethylene, or from about 90 to 100 wt %
polypropylene and from 0 to about 10 wt % low density polyethylene.
Numerous other combinations of materials are contemplated. For
exanzple, the oil resistant layer may include from about 50 to 100 wt %
polypropylene, from 0 to about 50 wt % low density polyethylene, and from 0
to about 30 wt % filler, such as, for example, calcium carbonate. As another
example, the oil resistant layer may include from about 15 to about 80 wt %
polypropylene, from about 1 to about 40 wt % low density polyethylene, and
from about 10 to about 30 wt % filler. As yet another example, the oil
resistant
layer may include from about 30 to about 80 wt % polypropylene, from about
10 to about 30 wt % low density polyethylene, and from about 5 to about 20 wt
% filler.
Each of the various layers may have any suitable weight, and may be
present in the packaging material in any suitable amount. The substrate, which
may be, for example, paper or paperboard, may have a basis weight of from
about 8 to about 250 lbs/ream. In one aspect, the substrate has a basis weight
of from about 20 to about 50 lbs/ream. In another aspect, the substrate has a
basis weight of from about 35 to about 45 lbs/ream.
The oil resistant layer generally may have a basis weight of from about
0.05 to about 25 lbs/ream. In one aspect, the oil resistant layer has a basis
weight of from about 1 to about 10 lbs/ream. In another aspect, the oil
resistant
layer has a basis weight of from about 2 to about 6 lbs/ream. In yet another
aspect, the oil resistant layer has a basis weight of from about 3 to about 5
lbs/ream. In still another aspect, the oil resistant layer has a basis weight
of
from about 1 to about 3 lbs/ream. In yet another aspect, the oil resistant
layer
has a basis weight of from about 2 to about 4 lbs/ream. In still another
aspect,
the oil resistant layer has a basis weight of from about 2 to about 5
lbs/ream.
FIG. 2 depicts another exemplary packaging material 200 according to
the present invention. In this example, a heat seal layer 205 substantially
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overlies all or a portion of the oil resistant layer 210, which substantially
overlies at least a portion of the substrate 215. A heat seal layer 205 may be
used where, for example, thermal bonding is used to form a package (not
shown) from the packaging material 200.
In this and other aspects, the heat seal layer may be formed from any
suitable thermoplastic polymeric material. Typically, the heat seal layer is
forined from a material having a low melting or softening point, such that the
heal seal can be initiated at a relatively low temperature ("heat seal
temperature"). Additionally, the material used to form the heat seal layer may
be selected to have a wide hot tack sealing window, such that the heat seal
may
be formed over a range of temperatures with the desired duration and degree of
tackiness.
By way of example, and not by limitation, the heat seal layer may be
formed from a low density polyethylene having a heat seal temperature of from
about 180 F to about 380 F. Examples of low density polyethylene resins that
may be suitable for use with the present invention in the heat seal layer
include,
but are not limited to, Westlake EC-482, commercially available from Westake
Chemical Corp. (Houston, Texas), VORIDIAN PE E6838-850P, commercially
available from Eastman Chemical Company (Kingsport, Tennessee), and
Marflex 1013 LDPE, commercially available from Chevron Phillips (The
Woodlands, Texas). However, it will be understood that other polymers, such
as, but not limited to, any of those described herein, or any blends or
copolymers thereof, may be used in accordance with the invention. For
example, it may be desirable to blend the heat seal layer polymer with the
polymer used to form the adjacent layer, in this example, the oil resistant
layer.
Alternatively, a portion of the heat seal layer polymer may be replaced with a
copolymer of the heat seal layer polymer and the oil resistant layer polymer,
such that the layers are more compatible and are able to attain better
adhesion
properties.
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Thus, if desired, the heat seal layer may include from 0 to about 50 wt %
of one or more polymers as a compatibilizing polymer, agent, or additive. In
one particular example, the heat seal layer includes from 0 to about 40 wt %
of
one or more compatibilizing polymers. In another example, the heat seal layer
includes from 0 to about 30 wt % of one or more compatibilizing polymers. In
yet another example, the heat seal layer includes from 0 to about 20 wt % of
one or more coinpatibilizing polymers. In still another example, the heat seal
layer includes from 0 to about 10 wt % of one or more compatibilizing
polymers. In yet a further example, the heat seal layer includes from 0 to
about
5 wt % of one or more compatibilizing polymers.
As with the various other layers of the packaging material, the heat seal
layer may be present in any suitable amount as needed or desired to achieve
the
desired heat seal. In one aspect, the heat seal layer has a basis weight of
from
about 0.1 to about 20 lbs/ream. In another aspect, the heat seal layer has a
basis weight of from about 1 to about 15 lbs/ream. In another aspect, the heat
seal layer has a basis weight of from about 3 to about 10 lbs/ream. In yet
another aspect, the heat seal layer has a basis weight of from about 3.5 to
about
9 lbs/ream. In still another aspect, the heat seal layer has a basis weight of
from about 2 to about 61bs/ream.
Thus, an exemplary packaging material according to the present
invention may include a layer of paper or paperboard having a basis weight of
from about 8 to about 250 lbs/ream, a layer of an oil resistant polymer, for
example, polypropylene, with optional additives, applied at a level of from
about 0.1 to about 20 lbs/reani, and a heat seal layer having a basis weight
of
from about 1 to about 15 lbs/ream. Another exemplary packaging material
may include a layer of paper or paperboard having a basis weight of from about
to about 60 lbs/ream, a layer of polypropylene with optional additives
applied at a level of from about 2 to about 6 lbs/ream, and a heat seal layer
having a basis weight of from about 3 to about 9 lbs/ream.
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FIG. 3A depicts still another exemplary packaging material 300
according to the present invention. In this exainple, a plurality of polymer
layers 305, 310, and 315 (also designated as layers A, B, and C, respectively)
overlie a substrate 320, for example, paper or paperboard (described above).
Each layer may serve one or more different functions within the structure. For
example, polymer layer 305, wliich substantially overlies the substrate 320,
may serve as a bonding or "tie" layer that joins polymer layer 310 to the
substrate 320. A tie layer may be used, for example, where two adjacent
layers, in this example, polymer layer 310 and substrate 320, are incompatible
or otherwise unable to attain sufficient adhesion. A tie layer may be located
between two polymer layers or two paper layers, or between a paper layer and
a polymer layer. Other uses for such layers are contemplated hereby.
A tie layer in accordance with this and other aspects of the invention
may be forined from any suitable polymer that sufficiently adheres to the
adjacent layers to join them. In one example, the heat seal layer is formed
from
a low density polyethylene, for example EC-482, described above. However, it
will be understood that other polymers, and blends or copolymers thereof, may
be used in accordance with the invention. For example, it may be desirable to
blend the tie layer polymer with the polymer used to form the adjacent layer,
in
this example, the oil resistant layer. Alternatively, a portion of the tie
layer
polymer may be replaced with a copolymer of the tie layer polymer and the oil
resistant layer polymer, such that the layers are more compatible and are able
to
attain better adhesion properties.
Thus, if desired, the tie layer may include from 0 to about 50 wt % of
one or more polymers as a compatibilizing polymer, agent, or additive. In one
particular example, the tie layer includes from 0 to about 40 wt % of one or
more compatibilizing polymers. In another example, the tie layer includes
from 0 to about 30 wt % of one or more compatibilizing polymers. In yet
another example, the tie layer includes from 0 to about 20 wt % of one or more
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compatibilizing polymers. In still another example, the tie layer includes
from
0 to about 10 wt % of one or more compatibilizing polymers. In yet a further
example, the tie layer includes from 0 to about 5 wt % of one or more
compatibilizing polymers.
The tie layer may have any suitable basis weight as needed to attain the
desired level of adhesion with the adjacent layers. For example, the tie layer
may have a basis weight of from about 0.1 to about 5 lbs/ream. Other basis
weights are contemplated hereby.
Still viewing FIG. 3A, polymer layer 310, which lies substantially
between polymer layer 305 and polymer layer 315, may serve as an oil resistant
layer. Such a layer may be formed from any suitable polymer and may have
any suitable basis weight, as described above. For example, polymer layer 305
may comprise polypropylene and, optionally, one or more other polymers
and/or fillers. As another example, polymer layer 305 and may have a basis
weight of from about 0.1 to about 20 lbs/ream, for example, from about 2 to
about 6 lbs/ream. Other polymers, compositions, and basis weights are
contemplated hereby.
Polymer layer 315, which substantially overlies polymer layer 310, may
serve as a heat seal layer. Such a layer may be formed from any suitable
polymer and may have any suitable basis weight, as described above. For
example, polymer layer 315 may comprise low density polyethylene and,
optionally, one or more other polymers. As another exainple, polymer layer
315 may have a basis weight of from about 1 to about 15 lbs/ream, for
example, from about 3 to about 5 lbs/ream. Other polymers, compositions, and
basis weights are contemplated hereby.
In this and other aspects, the various materials according to the
invention may be formed in any suitable manner using one or more techniques
known to those of skill in the art. In one example, each layer 305, 310, and
315
of the material 300 is formed using a separate extruder, as shown
schematically
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in FIG. 3B. One or more of the layers may be coextruded or, alternatively,
may be formed and/or joined in a sequential manner. Numerous other
processes are contemplated hereby.
If desired, one or more of the layers may be formed from the same type
of polymer, as shown in FIGS. 4A and 4B. In this exemplary packaging
material 400, a plurality of polymer layers 405, 410, and 415 substantially
overlie a substrate 420, for example, paper or paperboard (described above).
Polymer layers 405 and 415 each are designated as being formed from polymer
type A, and polymer layer 410 is designated as being formed from polymer
type B. In this example, polymer layer 405, which substantially overlies the
substrate 420, may serve as a bonding or tie layer that joins the various
other
polymer layers 410 and 415 to the substrate 420. Polymer layer 410, which lies
substantially between polymer layer 405 and polymer layer 415, may serve as
an oil resistant layer. Polymer layer 415, which substantially overlies
polymer
layer 410, may serve as a heat seal layer. Examples of basis weights and
compositions for the various layers are provided throughout this specification
and numerous others are contemplated hereby.
The packaging material 400 may be formed in any suitable manner. For
example, one extruder may be used to form polymer layers 405 and 415, and
another may be used to form polymer layer 410, as shown schematically in
FIG. 4B. One or more of the layers may be coextruded or, alternatively, may
be formed and/or joined in a sequential manner. Numerous other processes are
contemplated hereby.
It will be understood that numerous other structures and packaging
materials are contemplated hereby. For example, a four layer structure is
contenlplated in which a first tie layer is compatible with and substantially
overlies the substrate, a second tie layer is compatible with and
substantially
lies between the first tie layer and an oil resistant layer, and a heat seal
layer
substantially overlies the oil resistant layer. As another example, a five
layer
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structure is contemplated in which a third tie layer substantially lies
between
the heat seal layer and the oil resistant layer.
The present invention also contemplates a method of making a
packaging material having increased resistance to permeation by oil. The
method includes providing a substrate that may be permeable to oil and,
therefore, subject to staining, and substantially overlying at least a portion
of
the substrate with an oil resistant material or layer, for example, a resin or
polymeric film. The oil resistant layer may include one or more additives
optionally added to resin or film to impart additional functional
characteristics,
such as color, absorbency, improved adhesion, oil repellency, or numerous
other attributes. A heat seal layer may be applied or joined to at least a
portion
of the oil resistant layer to allow the packaging material to be sealed. One
or
more tie layers may be included to improve adhesion between various other
layers. Still other layers may be incorporated to serve various other
functions.
The various layers of the packaging material may be formed, assembled,
and/or joined using any method or technique known in the art. Thus, for
example the polymeric layers may be coextruded and laminated to the paper
layer. In another example, each layer may be formed independently and
laminated together using heat, adhesive, mechanical fastening, or other
joining
or binding technique. In yet another example, the polymeric layers may be
extruded directly onto the paper layer, concurrently or sequentially. Numerous
other processes are contemplated hereby.
In this and other aspects, the packaging material may be formed into any
suitable package, for example, a bag. The bag may have any shape and size as
needed for a particular food item and application. For some applications, for
example, for French fries, the bags may include slits or other features to
permit
the air to escape after filling the bag. This allows a plurality of bags to be
packed more efficiently into boxes or other cartons for shipping.
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Any suitable process may be used to form and fill the bag. In many of
such processes, heat is used to seal the open ends of the package together.
However, any suitable adhesive, mechanical fastening, joining, or binding
technique may be used with the present invention.
Oil Masking Materials
According to another aspect of the present invention, a packaging
material includes features that mask oil penetration of a substrate. It has
been
found that oil often causes the substrate to become translucent or
transparent,
thereby creating a visible stain on, for example, paper or paperboard,
particularly where there is a seam, abrasion, aperture, or slit through the
material. Accordingly, at least a portion of the substrate may be modified to
mask the appearance of a darkened region created by oil penetration.
Various approaches for masking a stain are contemplated by this
invention. Examples of such approaches include, but are not limited to, use of
one or more opacity modifying additives, use of opacity modifying fibers, use
of one or more colorants, and use of various printing patterns to minimize the
appearance of a darkened region of a substrate. The opacity modifying
additives, colorants, or combination thereof, may be applied or incorporated
throughout the material, may be applied or incorporated in a pattern, may be
selectively applied or incorporated in particular areas, may be applied or
incorporated in a somewhat random manner, or any combination thereof, as
appropriate.
Opacity modifying additives may be used in numerous ways to mask the
appearance of oil stains. Examples of opacity modifying additives that may be
suitable for use with the present invention include titanium dioxide, calcium
carbonate, talc, or clay, and any combination thereof. It will be understood
that
some opacity modifying additives are also colorants, and that some colorants
are also opacity modifying additives.
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In one aspect, an opacity modifying additive may be incorporated into
the substrate to make the substrate more white and opaque. In one particular
example, titanium dioxide is added to the substrate. For example, from about
20 to about 180 lb/ton titanium dioxide may be added to a paper having a basis
weight of from about 15 to about 160 lbs/ream, or in any amount needed to
achieve the desired results. In one particular example, from about 20 to about
180 lb/ton titanium dioxide may be added to a paper having a basis weight of
from about 30 to about 50 lbs/ream.
In another aspect, a layer of polymer containing titaniuin dioxide or
other opacity modifying additive may be coated onto, extruded onto, laminated
to, or otherwise applied to the substrate. To do so, the opacity modifying
additive may be blended or compounded with a polymer and subsequently
metered into an extruder, so that the polymer extrusion contains a
substantially
uniform amount of the opacifying agent. Such layers may be added, for
example, as one or more layers of a multilayer structure, such as those
described above, or may be applied directly to the substrate without other
polymer layers. Where such a polymer layer is used, the packaging material
may be formed into a package such that the opacified polymer layer lies on the
inside of the package in contact with the food item and/or on the outside of
the
package, as needed or desired for a particular application.
In still another aspect, where the substrate is paper-based, bleached
fibers that tend to be whiter may be used to form the substrate instead of or
in
addition to unbleached wood pulp fibers. Generally, from 0 to 100 wt % of the
fibers used to form the substrate may be bleached fibers. In each of various
examples, the substrate independently may be forined from about 10 to 100 wt
% bleached fibers and from 0 to about 90 wt % unbleached fibers, from about
20 to 100 wt % bleached fibers and from 0 to about 80 wt % unbleached fibers,
from about 30 to 100 wt % bleached fibers and from 0 to about 70 wt %
unbleached fibers; from about 40 to 100 wt % bleached fibers and from 0 to
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about 60 wt % unbleached fibers, from about 50 to 100 wt % bleached fibers
and from 0 to about 50 wt % unbleached fibers, from about 60 to 100 wt %
bleached fibers and from 0 to about 40 wt % unbleached fibers, from about 70
to 100 wt % bleached fibers and from 0 to about 30 wt % unbleached fibers,
from about 80 to 100 wt % bleached fibers and from 0 to about 20 wt %
unbleached fibers, or from about 90 to 100 wt % bleached fibers and from 0 to
about 10 wt % unbleached fibers. Other ranges and ratios of fiber types are
contemplated hereby.
In yet another aspect, the fiber content of the substrate may include at
least about 10 wt % bleached fiber. In each of various other examples, the
fiber content of the substrate independently may include at least about 15 wt
%
bleached fiber, at least about 20 wt % bleached fiber, at least about 25 wt %
bleached fiber, at least about 30 wt % bleached fiber, at least about 35 wt %
bleached fiber, at least about 40 wt % bleached fiber, at least about 45 wt %
bleached fiber, at least about 50 wt % bleached fiber, at least about 55 wt %
bleached fiber, at least about 60 wt % bleached fiber, at least about 65 wt %
bleached fiber, at least about 70 wt % bleached fiber, at least about 75 wt %
bleached fiber, at least about 80 wt % bleached fiber, at least about 85 wt %
bleached fiber, or at least about 90 wt % bleached fiber. In still another
example, the fiber content of the substrate may include at least about 90 wt %
bleached fiber. In each example, the remaining fibers may be unbleached
fibers or any other suitable fiber.
In another example, the substrate may have a basis weight of from about
to about 50 lbs/ream, for example 40 lbs/ream, and may include at least
about 25 wt % bleached fibers, and the opacity modifying additive comprises at
least about 90 lbs of titanium dioxide per ton of paper. In still another
example, the substrate may have a basis weight of from about 30 to about 50
lbs/ream, for example 40 lbs/ream, and may include at least about 25 wt %
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bleached fibers, and the opacity modifying additive comprises at least about
90
lbs of titanium dioxide per ton of paper.
The opacity of the unmodified substrate may depend on numerous
factors, for example, what the substrate is formed from and what the basis
weight of the substrate is. Thus, by adding an opacity modifying additive,
opacity modifying fibers, or opacity modifying layers, the opacity of the
substrate may increase in various relative amounts. For example, in each of
various examples, the modified substrate independently may have an opacity
that is from about 5 to about 20 percent greater than the unmodified
substrate,
from about 20 to about 40 percent greater than the unmodified substrate, from
about 40 to about 60 percent greater than the unmodified substrate, from about
60 to about 80 percent greater than the unmodified substrate, from about 80 to
about 100 percent greater than the unmodified substrate, from about 100 to
about 120 percent greater than the unmodified substrate, from about 120 to
about 140 percent greater than the unmodified substrate, from about 140 to
about 160 percent greater than the unmodified substrate, from about 160 to
about 180 percent greater than the unmodified substrate, or from about 180 to
about 200 percent greater than the unmodified substrate. Still greater
differences in opacity are contemplated hereby.
In still another aspect of the invention, the appearance of an oil stain
may masked by a colorant applied to the surface of the substrate viewed by the
user. As used herein, the term "colorant" means to any substance designed to
impart color to the surface of the substrate. Thus, the term colorant is
intended
to include, for example, pigments, inks, paints, or any combination thereof.
Colorants also may modify other attributes of the material, such as opacity
and
brightness, as will be known to those in the art.
The colorant type and composition selected and amount applied to or
incorporated into the substrate may vary depending on the type of substrate
chosen, the basis weight of the substrate, the modified or natural opacity of
the
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substrate, the type of food item being packaged, the amount of oil on the food
item, the degree of stainiug that occurs, the color of the stain on the
substrate,
and whether a combination of techniques are used to mask the appearance of
staining. Thus, while various examples are provided herein, it will be
understood the numerous other combinations of substrates and colorants are
contemplated hereby.
In each of various examples, the colorant composition may be applied in
an amount of from about 0.1 to about 10 lbs/ream, from about 0.5 to about 8
lbs/ream, from about 0.7 to about 5 lbs/ream, from about 0.8 to about 3.5
lbs/ream, from about 1 to about 3 lbs/ream, about 1 lbs/ream, about 1.25
lbs/ream, about 1.5 lbs/ream, about 1.75 lbs/ream, about 2 lbs/ream, about
2.25
lbs/ream, about 2.5 lbs/ream, about 2.75 lbs/ream, about 3 lbs/ream, or in any
other amount as needed or desired for a particular application.
In one aspect, the specific color of the colorant may be chosen to
resemble closely or to overpower the appearance of a stain on the substrate
caused by oil permeating through the substrate. In this manner, the colorant
serves to mask the stain and, thus, to prevent the user from detecting the oil
stain on the outside surface of the finished package. While the use of any
color
is contemplated hereby, dark colors, such as black or grey, may be
particularly
suitable for concealing the color variation associated with an oil stain. Such
colors absorb a full, or nearly full, spectrum of light, thereby blocking or
concealing the portions of the substrate that have become transparent or
translucent due to oil staining. Furthermore, it may be advantageous to use an
inorganic colorant. Such colorants tend to be more opaque, as compared with
organic pigments, which often are somewhat translucent.
For example, the colorant may include carbon black, titanium dioxide,
or various combinations thereof. A typical composition may include from
about 0.25 to about 5 dry lbs/ream (3000 sq. ft.) carbon black ink solids (or
"non-volatiles") and from about 10 to about 180 lbs/ton titanium dioxide in
the
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substrate. In one aspect, the colorant composition includes from about 0.35 to
about 3 dry lbs/ream carbon black ink solids and from about 20 to about 150
lbs/ton titanium dioxide. In another aspect, the colorant composition includes
from about 0.4 to about 2 dry lbs/ream carbon black ink solids and from about
40 to about 140 lbs/ton titanium dioxide. In yet another aspect, the colorant
composition includes from about 0.5 to about 2 dry lbs/ream carbon black ink
solids and from about 50 to about 135 lbs/ton titanium dioxide in the
substrate.
The masking efficiency of the ink or other colorant may be enhanced
using a metallic or other reflective pigment. While not wishing to be bound by
theory, the presence of such a pigment in the ink or colorant composition is
believed to eiihance stain masking because the metallic ink reflects light,
thereby obscuring the glossy appearance of the oil stained substrate. Examples
of reflective pigments that may be suitable for use with the present invention
include aluminum flake, brass flake, pearlescent pigments, or other light
reflecting pigments, or any combination thereof. Some examples of
pearlescent pigments that may be suitable for use with the present invention
include those offered by EM Industries, Inc. Some examples of reflective
pigments that may be suitable for use with the present invention are available
from Benda-Lutz Co. under the trade names Blitz Aluminum Powders and
Blitz Goldbronze Powder. Other materials are contemplated hereby.
Thus, in one aspect, a colorant composition used in accordance with the
present invention may include a pigment that sufficiently conceals the color
of
an oil stain on the particular substrate, for example, a non-reflective
pigment.
In another aspect, a colorant composition used in accordance with the present
invention may include a pigment that sufficiently obscures the glossiness
associated an oil stain on the particular substrate, for example, a reflective
pigment. In yet another aspect, a colorant composition may include a first
pigment, for example, a non-reflective pigment, that conceals the color of an
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oil stain and a second pigment, for example, a reflective pigmeiit, that
obscures
the glossiness associated with the oil stain.
Thus, in each of various examples, the pignlent independently may
include from 0 to about 10 wt % reflective pigment and from about 90 to 100
wt % non-reflective pigment, from about 10 to about 20 wt % reflective
pigment and from about 80 to 90 wt % non-reflective pigment, from about 20
to about 30 wt % reflective pigment and from about 70 to 80 wt % non-
reflective pigment, from about 30 to about 40 wt % reflective pigment and
from about 60 to 70 wt % non-reflective pigment, from about 40 to about 50 wt
% reflective pigment and from about 50 to 60 wt % non-reflective pigment,
from about 50 to about 60 wt % reflective pigment and from about 40 to 50 wt
% non-reflective pigment, from about 60 to about 70 wt % reflective pigment
and from about 30 to 40 wt % non-reflective pigment, from about 70 to about
80 wt % reflective pigment and from about 20 to 30 wt % non-reflective
pigment, from about 80 to about 90 wt % reflective pigment and from about 10
to 20 wt % non-reflective pigment, or from about 90 to 100 wt % reflective
pigment and from 0 to 10 wt % non-reflective pigment.
In each of various other examples, the pigment independently may
include from 0 to about 10 wt % aluminum flake and from about 90 to 100 wt
% carbon black, from about 10 to about 20 wt % aluminum flake and from
about 80 to 90 wt % carbon black, from about 20 to about 30 wt % aluminum
flake and from about 70 to 80 wt % carbon black, from about 30 to about 40 wt
% aluminum flake and from about 60 to 70 wt % carbon black, from about 40
to about 50 wt % aluminum flake and from about 50 to 60 wt % carbon black,
from about 50 to about 60 wt % aluminum flake and from about 40 to 50 wt %
carbon black, from about 60 to about 70 wt % aluminum flake and from about
to 40 wt % carbon black, from about 70 to about 80 wt % aluminum flake
and from about 20 to 30 wt % carbon black, from about 80 to about 90 wt %
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aluminum flake and from about 10 to 20 wt % carbon black, or from about 90
to 100 wt % aluminum flake and from 0 to 10 wt % carbon black.
In each of still other examples, the pigment independently may include
from about 1 to about 50 wt % aluminum flake and from about 50 to about 99
wt % carbon black, from about 20 to about 40 wt % aluminum flake and from
about 60 to about 80 wt % carbon black, from about 30 to about 50 wt %
aluminum flake and from about 50 to about 90 wt % carbon black, from about
20 to about 60 wt % aluminum flake and from about 40 to about 80 wt %
carbon black, from 0 to about 50 wt % aluminum flake and from about 50 to
100 wt % carbon black, or any other amount or range of amounts of each
component.
If desired, the one or more pigments may be blended into a stable
emulsion of binder, vehicle, wax, and dispersing liquid, such as water or
another suitable solvent, to form a colorant composition.
It will be understood that the various opacity modifying additives,
opacity modifying fibers, and/or colorants (collectively "masking additives")
described herein or contemplated hereby may be incorporated into the material
in any suitable manner. In one example, the masking additive may be
incorporated into the substrate during formation of the substrate. Thus, where
the substrate is paper or paperboard, the additive may be added during the wet
end processing of the pulp. Where the masking additive is an opacity
modifying additive, opacity modifying fiber, or colorant, this advantageously
may result in a substantial distribution of additive throughout the bulk of
the
substrate.
In another example, the masking additive may be applied to the
substrate after formation. Thus, for example, where the masking additive is a
colorant, the colorant may be applied to the surface of the substrate. Any
suitable process may be used, including any of numerous spraying, roll
coating,
brush coating, saturating, printing, foaming, and other techniques. In one
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particular example, printing may be used to apply a colorant to achieve a very
thin, uniform layer to the surface of the substrate.
Any combination of processes may be used to form a material according
to the present invention. Thus, for example, one colorant, such as carbon
black, may be printed on the outside, and another colorant, such as titaniunl
dioxide, may be added to the paper as a wet end constituent.
In each of the various aspects discussed herein, it will be understood by
those of skill in the art that one or more processing additives may be
incorporated into any of the various compositions or layers as needed or
desired. Thus, for example, some such layers or compositions may include
surfactants, anti-foaming agents, plasticizers, and additives to modify
abrasion
resistance and slip. Other processing additives are contemplated hereby.
According to yet another aspect of the present invention, stain masking
may be enhanced by applying or incorporating the colorant in a solid,
patterned, or random configuration. In some instances, a random printing
pattern or randomly printed pattern may enhance masking of stains by
camouflaging the variation in color of the stained substrate, for example,
where
the stains tend to appear around exhaust air slits in the package. In other
instances, a solid or patterned configuration may achieve the desired degree
of
masking.
It will be understood that any combination of techniques and features
described herein or contemplated hereby may be used in accordance with the
invention. Various aspects of the present invention are illustrated further by
the following examples, which are not to be construed as limiting in any
manner.
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OIL RESISTANCE TEST
Various samples were evaluated according to the following procedure:
First, a 6 inch by 10 inch sample sheet is provided. Two hard folds are
made on one side of the sample material, so the two folds make a cross right
at
the center of one side of the pouch. The sheet is folded in half and the short
sides are sealed carefully. One tablespoon of sand is placed into a beaker to
which add 1 plastic eye-dropper of red-dyed non-trans fatty acid oil is added
and mixed. The red, oily sand is spooned into the pouch, making sure not to
contaminate the seal area with sand or oil. The sides of the pouch are pressed
to remove as much air as possible. The open end of the pouch is heat sealed.
Any sample in which the seal is contaminated, creased, or otherwise not well
formed is discarded. Five sample pouches are prepared and placed on blotter
paper.
For room temperature evaluation, each batch of five samples is observed
at room temperature, typically at about 72 F and about 50% humidity, for signs
of red oil soak-thru every hour for the first two hours, and then about every
3
hours thereafter for 24 hours.
For evaluation at 50 C, each batch of five samples is placed in an oven
maintained at about 50 C. The samples are observed for red oil soak-thru
about every 20 minutes for the first two hours, and then every hour thereafter
for 24 hours.
For evaluation at 80 C, each batch of five samples is placed in an oven
maintained at about 80 C. The samples are observed for red oil soak-thru
about every 10 minutes for the first hour, every 30 minutes thereafter for 8
hours, and thereafter every 3 hours for 24 hours.
The amount of red stain at each time interval is reported and averaged.
A sample has failed when about 25% of the surface shows red oil soak-thru.
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EXAMPLE 1
Use of an oil resistant layer in the packaging material was evaluated. A
an about 2 lbs/ream layer of low density polyethylene obtained from Westlake
Chemical Corp. (Houston, Texas) under the trade name EC 482 was applied to
natural Kraft paper having a basis weight of about 38 lbs/ream. An about 4
lbs/ream layer of polypropylene obtained from Phillips Sumika under the trade
name Marlex then was extruded onto the rough, uncoated side of the Kraft
paper. The layers successfully adhered to one another. An about 4 lbs/ream
layer of EC 482 LDPE including heat seal additives then was extruded on top
of the polypropylene as the heat seal layer. Using the Oil Resistance Test,
the
oil resistant material effectively resisted penetration of Wesson canola oil,
a
non-trans fatty acid oil.
EXAMPLE 2
Use of an oil resistant layer in the packaging material was evaluated. A
blend of 68 wt % polypropylene obtained from Phillips Sumika under the trade
name MARLEX, 20 wt % low density polyethylene obtained from Westlake
Chemical Corp. (Houston, Texas) under the trade name EC 482, and 12 wt %
calcium carbonate obtained from Bayshore under the trade name BL-910 was
prepared. The calcium carbonate was added to improve adhesion to the
substrate. About 4 lbs/ream of the composition was extrusion coated onto
natural Kraft paper having a basis weight of about 38 lbs/ream. An about 4
lbs/ream layer of EC 482 LDPE including heat seal additives then was extruded
on top of the polypropylene as the heat seal layer. This composition
effectively
adhered to the paper substrate and provided good resistance to non-trans fatty
acid oil as measured by the Oil Resistance Test.
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EXAMPLE 3
The effectiveness of a masking colorant composition including a
metallic pigment was compared with composition without a metallic pigment.
The compositions evaluated are presented below.
Ink formulation I (blaclc)
about 20 wt % carbon black pigment
about 23 wt % other components (e.g., binder, resin, surfactant, wax)
remainder water
Ink formulation II "Pewter" (slight metallic cast)
about 14 wt % carbon black pigment
about 4.7 wt % aluminum flake
about 21 wt % other components (e.g., binder, resin, surfactant, wax)
remainder water
Ink formulation III (metallic silver-black)
about 6.7 wt % carbon black pigment
about 9.8 wt % aluminum flake
about 20 wt % other components (e.g., binder, resin, surfactant, wax)
remainder water
Ink formulation IV (black with slight metallic cast)
about 17.48 wt % carbon black pigment
about 7.77 wt % aluminum flake
about 69.88 wt % other components (e.g., binder, resin, surfactant, wax)
remainder water
The ink compositions were coated onto the smooth side of the paper in
amount of about 1 lb dry/ream. Then, about 6 lbs/ream of low density
polyethylene was extrusion coated onto the wire side of paper having a basis
weight of about 40 lbs/ream. The various compositions effectively masked
staining, as indicated in Table 1.
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Table 1.
Formula I Formula II Formula III Formula IV
Description Carbon Carbon black Carbon black Carbon
black w/aluminum w/aluminum black
flake flake w/aluminum
(6.15:1) (2.26:1) flake
(2.25:1)
Masking Fair; grease Excellent Outstanding Superb
Effectiveness stain faint masking; masking; oil masking; oil
but visible on stains barely stains barely
discernible close discernible discernible
inspection
EXAMPLE 4
The independent effect and the combined effect of using an opacity
modifier and/or bleached fibers was evaluated. The results are presented in
Table 2.
Table 2.
lbs Ti02/ton of Bleached fiber* Bleached fiber Bleached fiber
about 401bs/ream 0% 25% 50%
pa-per
0 Stain highly Stain masked but
visible still visible
54 Some masking
achieved
90 Good masking
achieved
180 Stain masked but Stain barely
still visible visible
* remainder is unbleached natural Kraft fiber
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EXAMPLE 5
Use of a printed masking pattern was evaluated. A flexographic print
plate was prepared from a picture of a large tub of potatoes. The picture
included light and dark areas that define the shape of potatoes. Formulae I,
II,
and III of Example 3 were printed onto a natural Kraft paper having a basis
weight of about 401bs/ream in the desired pattern. The results are presented
in
Table 3.
Table 3.
Formula I Formula II Formula III
Masking Good; grease Excellent; Superb; oil stains
Effectiveness stain faint but stain is scarcely nearly invisible even
discernible visible on close with close inspection
inspection discernible
EXAMPLE 6
A flexible, substantially two-dimensional, oil resistant packaging
material was formed from a layer of paper coated with an oil resistant
polymer.
The coated paper was formed into a pouch or package in which oily products
were sealed and handled. Oil stains that typically are visible on the outside
of
the sealed package were less visible or not visible at all.
EXAMPLE 7
A black ink was printed in a solid configuration on the outside surface of
the packaging material of Example 6, thereby rendering oil stains more
difficult
to see conlpared to non-printed portions of the paper.
EXAMPLE 8
An ink containing about 96% carbon black and about 4% finely divided
aluminum pigment was printed in a solid configuration on the outside surface
of the packaging material of Example 6. Oil stains were masked effectively.
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EXAMPLE 9
An ink containing about 10% fmely divided aluminum and about 90%
carbon black was printed in a solid configuration on the outside surface of
the
packaging material of Example 6. Oil stains were masked effectively.
EXAMPLE 10
A 100 % carbon black ink was printed onto the outside surface of the
packaging material of Example 6 in various configurations. A random printing
pattern of lighter and darker shades was more effective at stain masking than
a
solid printing pattern.
EXAMPLE 11
An ink containing about 96% carbon black and about 4% finely divided
aluminum was printed onto the outside surface of the packaging material of
Example 6 in various configurations. A random printing pattern was more
effective at masking stains than a solid printing pattern.
EXAMPLE 12
An ink containing about 90% carbon black and about 10% finely
divided aluminum was printed onto the outside surface of the packaging
material of Example 6 in various configurations. A random printing pattern
was more effective at masking stains than a solid printing pattern.
Accordingly, it will be readily understood by those persons skilled in the
art that, in view of the above detailed description of the invention, the
present
invention is susceptible of broad utility and application. Many adaptations of
the present invention other than those herein described, as well as many
variations, modifications, and equivalent arrangements will be apparent from
or
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reasonably suggested by the present invention and the above detailed
description thereof, without departing from the substance or scope of the
present invention.
While the present invention is described herein in detail in relation to
specific aspects, it is to be understood that this detailed description is
only
illustrative and exemplary of the present invention and is made merely for
purposes of providing a full and enabling disclosure of the present invention
and for setting forth the best mode contemplated by the inventor of carrying
out
the invention. The detailed description set forth herein is not intended nor
is to
be construed to limit the present invention or otherwise to exclude any such
other embodiments, adaptations, variations, modifications, and equivalent
arrangements of the present invention.
33
