US20070000568A1

US20070000568A1 - Packaging material for food items containing permeating oils

Info

Publication number: US20070000568A1
Application number: US11/477,264
Authority: US
Inventors: Reinhard Bohme; John Files
Original assignee: Individual
Current assignee: Graphic Packaging International LLC
Priority date: 2005-06-29
Filing date: 2006-06-29
Publication date: 2007-01-04
Also published as: WO2007002896A3; CA2613927A1; WO2007002896A2

Abstract

A packaging material for oily or greasy food items includes one or more features for resisting penetration, masking penetration, or for a combination of resisting and masking penetration by the oily or greasy substance.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 60/695,145, filed Jun. 29, 2005, the disclosure of which is incorporated by reference herein in its entirety.

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 no-trans fatty oils has increased because these oils are viewed as healthier than other oils. However, unlike other oils, which freeze at typical freezer temperatures, the no or low trans oils remain fluid, thereby causing greater staining to the package.

SUMMARY

Various aspects of the present invention relate generally to a packaging material for oily or greasy food items. The packaging material includes features for resisting penetration, masking penetration, or for a combination of resisting and masking penetration by the oily substance. Other aspects and features of the present invention will become apparent in view of the figures and the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views, and in which:
FIG. 1 depicts an exemplary packaging material according to various aspects of the present invention; and
FIG. 2 depicts another exemplary packaging material according to various aspects of the present invention.

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, a non-trans fatty acid, saturated oil, unsaturated oil, grease, or butter (collectively “oil” or “oils”), that potentially can penetrate one or more layers that form the packaging material. The material of the present invention includes features for resisting penetration, masking penetration, or for both resisting and masking oil penetration. It will be understood that any combination of the techniques and features disclosed herein and contemplated hereby may be used in any combination as needed or desired.
Oil Resistant Materials
According to one aspect of the present invention, a packaging material includes features that resist penetration by oil. For example, the packaging material may include an oil permeable substrate coated with one or more additional layers that resist penetration by oil.
In one aspect depicted in FIG. 1, the packaging material 10 may include a substrate 15, and an oil resistant layer 20 substantially covering the substrate 15. The substrate 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 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, 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 commercially available from Phillips under the trade name MARLEX®. One example of a polyethylene terephthalate that may be suitable for use with the present invention is commercially available from Toray under the trade name PA10. One example of a polyvinyl alcohol that may be suitable for use with the present invention is commercially available from DuPont under the trade name ELVANOL®. One example of a polyvinylidene chloride that may be suitable for use with the present invention is commercially available from Dow Chemical Company under the trade name SARAN®. One example of an ethylene vinyl alcohol that may be suitable for use with the present invention is commercially available from Evalco under the trade name Eval Resins. Another polymeric material that may be suitable is SURLYN®, commercially available from DuPont.
The oil resistant layer may include various other additives and components as desired. The other additives and components may be selected to improve adhesion to the paper substrate, 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 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.
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 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.
When the oil resistant layer includes other additives and components, various combinations with the polymeric material are contemplated hereby. Thus, each of the various components may have a weight percent greater than 0 up to 100 wt %. Thus, for example, the oil resistant layer may include from about 60 to about 100 wt % polypropylene, from 0 to about 40 wt % polyethylene, and from 0 to about 30 wt % filler, such as, for example, calcium carbonate. In another example, the oil resistant layer may include from about 15 to about 80 wt % polypropylene, from about 1 to about 40 wt % polyethylene, and from about 10 to about 30 wt % filler. In yet another example, the oil resistant layer may include from about 30 to about 80 wt % polypropylene, from about 10 to about 30 wt % polyethylene, and from about 5 to about 20 wt % filler.
FIG. 2 depicts another exemplary packaging material 25 according to the present invention. Where thermal bonding is used, a heat seal layer 30 optionally may overlie all or a portion of the oil resistant layer 20, which overlies the substrate 15. In this and other aspects, the heat seal layer may be formed from any suitable heat activatable thermoplastic polymeric material. Typically, the heat seal layer is formed from a material having a low melting point. In one aspect, the heat seal layer is formed from low density polyethylene that has a heat seal temperature of from about 180° F. to about 380° F. One example of a low density polyethylene that may be suitable for use with the present invention in the heat seal layer is commercially available from West Lake, under the trade name EC-482. As with the various other layers, 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 2 to about 12 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 6 lbs/ream.
Thus, in one example, the packaging material of 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 1 to about 10 lbs/ream, and a heat seal layer having a basis weight of from about 2 to about 12 lbs/ream. In another example, the packaging material of the present invention may include a layer of paper or paperboard having a basis weight of from about 30 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 6 lbs/ream.
In another aspect, the present invention contemplates a method of making a packaging material having increased resistance to permeation by oil. The method includes providing a substrate that is permeable to oil and, therefore, subject to staining. At least a portion of the substrate may be covered with an oil resistant layer formed from, 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.
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. 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.
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 an opacity modifier, use of a colorant, and use of various printing patterns to minimize the appearance of a darkened region. The opacity modifier, colorant, 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 random-looking manner, or any combination thereof, as appropriate.
Opacity Modifier
Various opacity modifiers may be used in numerous ways to mask the appearance of oil stains. Examples of opacity modifiers 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 modifiers are also colorants, and that some colorants are also opacity modifiers.
In one aspect, an opacity modifier 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 lb/ream, or in any amount needed to achieve the desired results.
In another aspect, bleached fibers, which tend to be whiter, may be used to form the substrate, instead of or in addition to unbleached wood pulp fibers. For example, from about 10 to about 100% of the fibers used to form the substrate may be bleached fibers. The remaining fibers may be unbleached fibers or any other suitable fiber.
In yet another aspect, a layer of polymer containing titanium dioxide or other opacity modifier may be coated onto, extruded onto, laminated to, or otherwise applied to the substrate. To do so, an opacifying pigment may be blended with a polymer, and subsequently metered into an extruder so that the entire polymer extrusion contains some substantially uniform amount of the opacifying agent. Such layers may be added, for example, as the “core” layer of a multi-layer heat seal extrusion layer, 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.
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 modifier, the opacity of the substrate may increase in various relative amounts. For example, the modified substrate may have an opacity that is from about 5 to about 20 percent greater than the unmodified substrate. In another example, the modified substrate may have an opacity that is from about 20 to about 40 percent greater than the unmodified substrate. In yet another example, the modified substrate may have an opacity that is from about 40 to about 60 percent greater than the unmodified substrate. In still another example, the modified substrate may have an opacity that is from about 60 to about 80 percent greater than the unmodified substrate. In another example, the modified substrate may have an opacity that is from about 80 to about 100 percent greater than the unmodified substrate. In yet another example, the modified substrate may have an opacity that is from about 100 to about 120 percent greater than the unmodified substrate. In another example, the modified substrate may have an opacity that is from about 120 to about 140 percent greater than the unmodified substrate. In still another example, the modified substrate may have an opacity that is from about 140 to about 160 percent greater than the unmodified substrate. In another example, the modified substrate may have an opacity that is from about 160 to about 180 percent greater than the unmodified substrate. In a still further another example, the modified substrate may have an opacity that is from about 180 to about 200 percent greater than the unmodified substrate.
Masking Colorant
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, and 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 substrate, the type of food item being packaged, the amount of oil on the food item, the degree of staining that occurs, and the color of the stain on the substrate. Thus, while various examples are provided herein, it will be understood the numerous other combination of substrates and colorants are contemplated hereby.
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, non-reflective 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 3 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 substrate. In one aspect, the colorant composition includes from about 0.35 to about 2.5 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 0.4 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. The presence of such a pigment in the ink or colorant composition is believed to enhance 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.
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 that conceals the color of an oil stain and a second pigment that obscures the glossiness associated with the oil stain.
Typically, the one or more pigments used to form the colorant composition are blended into a stable emulsion of binder, vehicle, wax and dispersing liquid, such as water or another suitable solvent. Numerous compositions are contemplated hereby. For example, the colorant composition may include from 0 to about 50 wt % reflective pigment in the pigment phase of the ink, with the remainder being non-reflective pigment. In one aspect, the colorant composition may include from about 0.25 to about 30 wt % reflective pigment. In another aspect, the colorant composition may include from about 0.5 to about 20 wt % reflective pigment. In yet another aspect, the colorant composition may include from about 3 to about 15 wt % reflective pigment. In still another aspect, the colorant composition may include from about 7 to about 12 wt % reflective pigment. Thus, for example, a colorant composition may include from about 1 to about 10 wt % finely divided aluminum and from about 90 to about 99 wt % carbon black in the pigment in the ink.
It will be understood that the various additives described herein or contemplated hereby may be incorporated into the material in any suitable manner. In one example, the 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 additive is an opacity modifier or colorant, this advantageously may result in a substantial distribution of additive throughout the bulk of the substrate.
In another example, the additive may be applied to the substrate after formation. Thus, for example, where the 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 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 titanium 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 other 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.
Masking Pattern
According to yet another aspect of the present invention, stain masking is enhanced by applying or incorporating the colorant in a solid, patterned, or random configuration. The random printed pattern enhances masking of stains by camouflaging the variation in color of the stained substrate. This is particularly true of the stains which appear around exhaust air slits in the package.
Various aspects of the present invention are illustrated further by the following example embodiments, which are not to be construed as limiting in any manner.

EXAMPLE EMBODIMENTS

In a first example embodiment, a flexible, substantially two-dimensional substrate is formed from a layer of paper coated with a layer of heat sealable polymeric resin. The coated paper can be formed into a pouch or package in which oily products are sealed and handled. Oil stains that typically are visible on the outside of the sealed package are less visible or not visible at all.
In a second example embodiment, a black ink is printed as a solid application on the outside surface of the coated paper of the first example embodiment. The black ink renders grease stains more difficult to see compared to non-printed portions of the paper.
In a third example embodiment, a black ink that contains finely a divided aluminum pigment is printed as a solid application on the outside surface of the coated paper of the first example embodiment. In one variation, a black ink having a pigment content of about 4% finely divided aluminum and 96% carbon black is used. In another variation, a silver black ink having a pigment content of about 10% fmely divided aluminum and about 90% carbon black is used.
In a fourth example embodiment, a black ink is printed onto the outside surface of the paper of the first example embodiment with in a random pattern of lighter and darker shades. In one variation, the random printing pattern is more effective at stain masking than a solid printing pattern. In another variation, a random printing pattern of an about 4% aluminum-containing black ink is more effective at masking stains than the same ink printed in a solid printing pattern. In another variation, a random printing pattern of an about 10% aluminum-containing black ink is more effective at masking stains than the same ink printed in a solid printing pattern.
Various aspects of the present invention are illustrated further by the following examples, which are not to be construed as limiting in any manner.
Oil Resistance Test
Various samples were evaluated according to the following procedure.
A 6″×10″ 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 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 72° F. and 50% humidity, for signs of red oil soak-thru every hour for the first two hours, and then 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 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 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.

Example 1

Use of an oil resistant layer in the packaging material was evaluated. A an about 2 lb/ream layer of low density polyethylene obtained from West Lake under the trade name EC 482 was applied to natural Kraft paper having a basis weight of about 38 lbs/ream. An about 4 lb/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 lb/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 West Lake 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 lb/ream of the composition was extrusion coated onto natural Kraft paper having a basis weight of about 38 lb/ream. An about 4 lb/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 oil as measured by the Oil Resistance Test.

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 (Black):

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 % black pigment
about 9.8 wt % aluminum flake
about 20 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 about 1 lb dry/ream. Then, about 6 lb/ream of low density polyethylene was extrusion coated onto the wire side of paper having a basis weight of about 40 lb/ream. The various compositions effectively masked staining, as indicated in Table I.

TABLE I


Formula I	Formula II	Formula III

Description	Carbon black	Carbon black	Carbon black
		w/aluminum flake	w/aluminum flake
		(6.15:1)	(2.26:1)
Masking	Fair; grease	Excellent	Superb; oil stains
Effectiveness	stain faint but	masking; visible	barely discernible
	discernible	on close
		inspection

Example 4

The independent effect and combined effect of using an opacity modifier and/or bleached fibers were evaluated. The results are presented in Table II.

TABLE II


lbs TiO2/ton of
about 40 lb/ream	Bleached fiber*	Bleached fiber	Bleached fiber
paper	0%	25%	50%

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

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 40 lbs/ream in the desired pattern. The results are presented in Table III.

TABLE III


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

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 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. 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.

Claims

1. 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,

wherein the oil resistant layer comprises a polymer that is substantially resistant to penetration by oil.

2. The packaging material of claim 1, wherein the oil resistant layer comprises a single polymer.

3. The packaging material of claim 1, wherein the oil resistant layer comprises polypropylene.

4. The packaging material of claim 1, wherein the oil resistant layer has a basis weight of from about 1 to about 10 lbs/ream.

5. The packaging material of claim 1, wherein the oil resistant layer has a basis weight of from about 2 to about 6 lbs/ream.

6. The packaging material of claim 1, wherein the oil resistant layer comprises a blend of two or more polymers.

7. The packaging material of claim 1, wherein the oil resistant layer comprises a filler.

8. The packaging material of claim 1, wherein the oil resistant layer comprises from 0 to about 30 weight % filler.

9. The packaging material of claim 1, wherein

the substrate comprises paper or paperboard; and

the oil resistant layer comprises polypropylene and a filler selected from the group consisting of calcium carbonate, magnesium carbonate, silica, calcium oxide, alumina, titanium dioxide, and any combination thereof.

10. The packaging material of claim 1, further comprising a heat seal layer substantially overlying the oil resistant layer.

11. The packaging material of claim 10, wherein the heat seal layer comprises a thermoplastic polymer having a softening temperature of from about 180° F. to about 380° F.

12. The packaging material of claim 11, wherein

the substrate comprises paper or paperboard;

the oil resistant layer comprises polypropylene; and

the heat seal layer comprises low density polyethylene.

13. The packaging material of claim 11, wherein

the paper or paperboard has a basis weight of from about 8 to about 250 lbs/ream;

the oil resistant layer has a basis weight of from about 1 to about 10 lbs/ream; and

the heat seal layer has a basis weight of from about 2 to about 12 lbs/ream.

14. A packaging material for masking staining by an oil, comprising:

a paper-based substrate that tends to absorb oils, the substrate being formed at least partially from bleached fiber and including at least one of titanium dioxide, calcium carbonate, talc, or clay.

15. The packaging material of claim 14, wherein

the substrate comprises paper having a basis weight of about 40 lbs/ream, and

the paper includes at least about 90 lbs of titanium dioxide per ton of paper and at least about 25 weight % bleached fiber.

16. The packaging material of claim 14, wherein

the substrate comprises paper having a basis weight of about 40 lbs/ream, and

the paper includes at least about 180 lbs of titanium dioxide per ton of paper and at least about 50 weight % bleached fiber.

17. A packaging material for masking staining by an oil, comprising:

a substrate that tends to absorb oils; and

an opacity modifying layer substantially overlying the substrate, the opacity modifying layer comprising a polymer and an opacity modifier.

18. The packaging material of claim 17, wherein the opacity modifier comprises titanium dioxide.

19. The packaging material of claim 17, further comprising a heat seal layer substantially overlying the opacity modifying layer distal the substrate.

20. A packaging material for masking staining by an oil, comprising:

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 comprising a colorant, wherein the colorant closely resembles the color of the stain, obscures the glossiness of the stain, or any combination thereof.

21. The packaging material of claim 20, wherein the colorant comprises a dark, non-reflective pigment that closely resembles the color of the stain.

22. The packaging material of claim 20, wherein the colorant comprises a reflective pigment that obscures the glossiness of the stain.

23. The packaging material of claim 20, wherein the reflective pigment comprises aluminum flake, brass flake, a pearlescent pigment, or any combination thereof.

24. The packaging material of claim 20, wherein 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.

25. The packaging material of claim 20, wherein the colorant comprises:

from about 50 to 100 weight % carbon black; and

from 0 to about 50 weight % aluminum flake.

26. The packaging material of claim 20, wherein the stain masking layer overlies at least a portion of the substrate in a substantially solid configuration.

27. The packaging material of claim 20, wherein the stain masking layer overlies at least a portion of the substrate in a patterned configuration.

28. The packaging material of claim 20, wherein 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.

29. The packaging material of claim 20, wherein an opacity modifier is incorporated into the substrate.

30. The packaging material of claim 29, wherein the opacity modifier comprises titanium dioxide.

31. The packaging material of claim 20, wherein

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.

32. The packaging material of claim 31, wherein the opacity modifying layer comprises a polymer and an opacity modifier.

33. The packaging material of claim 32, wherein the opacity modifier comprises titanium dioxide.

34. A packaging material for a food item containing an oil, comprising:

a paper-based substrate that appears to be stained when brought into contact with an oil;

an oil resistant layer substantially overlying the substrate, the oil resistant layer comprising

a polymer that is substantially resistant to penetration by oil, and

an opacity modifier;

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 stain masking layer comprising a colorant,

wherein the colorant

closely resembles the color of the stain,

obscures the glossiness of the stain, or

any combination thereof.

35. The packaging material of claim 34, wherein

the polymer in the oil resistant layer comprises polypropylene;

the opacity modifier comprises titanium dioxide; and

the heat seal layer comprises low density polyethylene.

36. The packaging material of claim 34, wherein

the substrate has a basis weight of from about 20 to about 50 lbs/ream;

the heat seal layer has a basis weight of from about 3 to about 10 lbs/ream.

37. The packaging material of claim 34, wherein 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.

38. The packaging material of claim 34, wherein the colorant comprises:

from about 50 to 100 weight % carbon black; and

from 0 to about 50 weight % aluminum flake.

39. A package formed from the packaging material of claim 34.

40. A package formed from the packaging material of claim 34 for containing potato-based food items.