Patent Application
20050008736
1. Field of the Invention
The invention relates to methods for applying oil and grease resistant coatings to packaging that can be used in high temperature applications and to the resulting packaging end product.
2. Description of Related Art
Consumer products are packaged in numerous manners to make use of the products contained within packaging more convenient for consumers. The more convenient it is for a consumer to use a product, the more likely the consumer will use the product. In addition to being convenient, the packaging must be capable of keeping the products contained within fresh and appealing. The package outside must also be aesthetically appealing. Often, to get the best protection for the goods within the packaging, the outer packaging quality has been sacrificed.
Packaging can be coated with various materials to increase certain properties of the packaging. This is particularly true when the product contained within is oily or greasy. For aesthetic reasons, for example, a paper substrate should be resistant to oil and grease stains and “stain proof” from both inside and outside of the package. Stain resistant materials can either be provided by the presence of a physical barrier or an oil and grease repellent material, e.g., fluorocarbons. Where only a repellent material is used, the oil and grease can pass or bleed through a fiber matrix within the substrate without showing a stain on the package, but staining of surfaces outside of a package can occur. If a physical barrier also is used, however, staining of external package surfaces are generally prevented. This stain proof requirement exists in manufacturing, packing, shipping and handling environments. Many times the stain proof substrate is the outer print ply of the packaging.
For years, most oil and grease resistant coatings contained chemicals known as fluorocarbons. These fluorocarbon-based coatings often are saturants applied by paper machines. An example of this type of coating having some fluorocarbon content is described in U.S. Pat. No. 5,674,961 by Fitzgerald titled “Oil Water And Solvent Resistant Paper By Treatment With Fluorochemical Copolymers” (“the '961 patent”). Synthetic fluorocarbons, however, have recently come under governmental and environmental group scrutiny due to their alleged potential deleterious environmental effects.
Prior attempts have been made to decrease the environmental effects of fluorocarbons. Alternative synthetic fluorocarbon paper treatments with more environmentally friendly characteristics have been developed. Problems still exist with these alternatives, however. For example, many of the alternatives such as described in the '961 patent still contain fluorocarbon content. Additionally, these fluorocarbon alternatives can be expensive to produce, and it is uncertain if a reliable supply source exists for the future.
One example of an attempt for more environmentally friendly oil and grease resistant compound is described in U.S. Pat. No. 4,097,297 by Keene titled “Barrier Coatings” (“the '297 patent”). The '297 patent describes an overprint varnish that is nitrocellulose based. Applicants have recognized, however, that problems still exist with these alternatives. The overprint varnish, for example, still contains fluorocarbons in a small percentage in its composition. This overprint varnish works better when used in a solution containing a solvent. The use of a solvent, however, adds considerable costs to the manufacturing process and the solvents may emit harmful volatile organic chemicals “VOC's” during application. Additionally, the method of drying the overprint varnish to substrates is inefficient and time-consuming. The drying process requires drying either with a heater, which increases capital costs, or at room temperature, which increases the time required to dry the overprint varnish.
It has been suggested that other natural compounds, such as starch compounds, can be used as extenders or additives in oil and grease resistant coatings to reduce the level of fluorocarbons required in the coating for packaging. Examples of such starch-based materials can be found in U.S. Pat. No. 6,528,088 titled “Highly Flexible Starch-Based Films” (“the '088 patent”) and U.S. Pat. No. 6,375,981 titled “Modified Starch As A Replacement For Gelatin In Soft Gel Films And Capsules” (“the '981 patent”), both by Gillenland et al. The performance of these materials for packaging applications, however, has been marginal. Applicants have recognized that these starch-based materials are too brittle for use as a fluorocarbon extender in forming primary oil and grease resistant compounds for many packaging material applications because the coating and packaging would be inflexible and would tend to crack or crease when shaped or formed. Additionally, because such fluorocarbon extender coatings tend to have relatively high viscosity, using such starch-based derivatives as an extender coating can cause difficulties when the coating is used in various paper-related packaging applications. For example, the typical conventional printing machinery that is used to apply the starch materials to the substrates cannot handle certain amounts of gel in the packaging materials. Gel formation is necessary, however, in the previously proposed fluorocarbon extender starch-based compounds to achieve the level of solids concentration required for sufficient oil and grease resistance properties. Because of the level of gel formation, the printing machinery cannot handle the high solids concentration within the starch material, and unsightly bubbles can form in the coating. As a result of these problems recognized by Applicants, the proposed use of starch-based compounds as extenders to reduce the level of fluorocarbons required in the coating is limited. Additionally, the environmental concerns inherent with the presence of fluorocarbons still remain when the starch-based compound is used as an extender.
In addition to the oil and grease resistance requirements, Applicants have recognized previously proposed fluorocarbon-extender alternative starch-containing packaging treatment materials have not shown other additional features that are sometimes desired in packaging, such as the capability for use in high temperature applications like microwave popcorn bags, microwavable food wrappers, and the like. U.S. Pat. No. 5,488,220 by Freerks et al. titled “Bag For Microwave Cooking,” U.S. Pat. No. 5,038,009 by Babbitt titled “Printed Microwave Susceptor And Packaging Containing The Susceptor,” and U.S. Pat. No. 5,171,594 by Babbitt titled “Microwave Food Package With Printed-On Susceptor” all contain examples of packaging that is used in high temperature applications, specifically microwave oven applications. Previously proposed fluorocarbon-alternative starch-containing packaging treatment materials, however, have shown minimal scorch resistance and tended to turn brown at higher temperatures.
Various other non-fluorocarbon alternatives have been developed to combat the environmental and other consequences of using fluorocarbons. Such developments include synthetic latexes, a combination of natural cellulosic gums, starch, and/or proteins, and heavy paper refining. Although these alternatives may be more environmentally friendly than fluorocarbons, there are still problems using these alternatives. The use of synthetic latexes or the combination of natural cellulosic gums, starch, and/or proteins requires very high coat weights when applying them to the paper substrates. The high coat weights result in poor paper machinery operation and increase the amount of maintenance required on these machines. Each of the alternatives is very costly, which makes them economically infeasible. Additionally, none of the three alternatives provide very good oil and grease resistance.
As another alternative to fluorocarbon components, plastic and polymer alternative packaging constructions have been developed. Applicants have recognized that problems also exist with these alternatives, however. The plastic and polymer packaging materials have very high raw material costs associated with them. These alternatives also operate less efficient on the converting and packing machinery. Additional equipment is also necessary when using these alternatives. This increases the capital assets that are required, which many times makes use of these alternatives economically infeasible.
Most packaging producers purchase paper substrates that are pretreated with oil and grease resistant materials, such as those described above. The packaging producers apply their graphics to the pretreated substrates, apply an overprint varnish over the graphics, and then form their end packaging products. This increases the raw material costs for these producers, since oil and grease resistant coatings increase the cost of the paper substrates.
With more and more products being packaged for consumer convenience, Applicants have recognized a need still exists for packaging that is environmentally friendly and provides superior barrier properties to oil and grease. With increased market competition, the packaging preferably needs to be able to be decorated aesthetically and possess enough strength to withstand the elements to which the packaging will be exposed. Applicants have also recognized a further need for a type of packaging that can provide needed oil and grease resistant properties, along with being able to perform well in high temperature applications and be sufficiently scorch resistant. Applicants have recognized yet a further need for a type of packaging that is sufficiently flexible and uses a coating that has a relatively low viscosity so that the coating can be effectively applied to various packaging substrates such as paper.
With the foregoing in mind, embodiments of the present invention advantageously provide a method for forming a non-fluorocarbon treated high temperature package having oil and grease resistant properties and related high temperature packages Embodiments of the present invention also advantageously provide a non-fluorocarbon treated high temperature package that has oil and grease resistant properties and is environmentally friendly and relatively economical to produce. Also, the package and method according to the embodiments of the present invention advantageously provide a package with coating that gives increased flexibility and resistance to cracking to the packaging material. The package and method according to the embodiments of the present invention additionally provide a package with a coating that is advantageously lower in viscosity, which increases compatibility with typical paper making equipment. Also, the package and method according to the present invention further provide a package with a coating that is advantageously resistant to browning and scorching at increased temperatures.
More particularly, a method of forming a non-fluorocarbon treated high temperature package having oil and grease resistant properties is provided according to embodiments of the present invention and includes supplying at least one outer substrate including a paper material having a grease resistant coating devoid of fluorocarbons thereon. The coating includes a starch-based film having a pre-selected percent by weight of at least one pre-selected starch derivative, a flexibility enhancing agent, a rheological agent, and a scorch resistant agent. The at least one starch derivative includes a chemically modified starch. The method also includes supplying at least one inner substrate including having a paper material also having the grease resistant coating thereon and printing indicia on an outer surface of the at least one outer substrate. The method additionally includes laminating the at least one outer substrate having indicia thereon to the at least one inner substrate to define a laminated substance. The laminated substrate is shaped to define a front panel, a back panel opposing the front panel, and a pair of opposing side panels each extending between the front panel and the back panel. The pair of opposing side panels each has a longitudinal accordion pleat therein defining longitudinal gusseted folds in the panels. The pair of gusseted side panels are expandable about folds therein during cooking of food in the package to enlarge an interior volume of the package.
According to another aspect of the present invention, the method can also include having the coating on the outer substrate positioned on the outer surface of the outer substrate and the inner surface of the outer substrate and the coating on the inner substrate positioned on the outer surface of the inner substrate and on the inner surface of the inner substrate. The method can also include supplying a high temperature susceptor, supplying a susceptor adhesive to the inner surface of the outer substrate, and positioning the high temperature susceptor to the susceptor adhesive. The laminating step can include applying a laminating adhesive to the susceptor and to the inner surface of the outer substrate and positioning the outer surface of the inner substrate on the laminating adhesive to thereby further define the laminated substrate.
Alternatively, the grease resistant coating on the outer substrate can be positioned on the outer surface of the outer substrate, and the coating on the inner substrate can be positioned on the inner surface of the inner substrate. The laminating step then can include applying a grease resistant laminating adhesive to an inner surface of the outer substrate and positioning an outer surface of the inner substrate on the grease resistance laminating adhesive to thereby further define the laminated substrate.
For example, the grease resistant coating on the at least one of the substrates can be supplied in a composition having a solids concentration by weight of about 10% to about 35% and preferably substantially free from a gel formation. The coating preferably has a viscosity in a range of about 65 centipoises to about 156 centipoises, and the solids concentration by weight, even more preferably, is in a range of about 20% to about 25%.
Another method according to an embodiment of the present invention of forming a non-fluorocarbon treated high temperature package having oil and grease resistant properties and having contents therein preferably includes supplying at least one outer substrate including a paper material having a grease resistant coating devoid of fluorocarbons thereon. The coating includes a starch-based derivative, a flexibility enhancing agent, and a rheological agent. At least one inner substrate is supplied including a paper material also having the coating thereon. The at least one outer substrate is laminated to the at least one inner substrate to define a laminated substrate. The laminated substrate is shaped to define a preselected package shape.
An embodiment of the present invention also provides a non-fluorocarbon treated high temperature package having oil and grease resistant properties and includes at least one substrate having a paper material. The substrate defining a front panel, a back panel opposing the front panel, a bottom panel, and a pair of opposing side panels each extending between the front panel and the back panel. The pair of opposing side panels each has a longitudinal accordion pleat therein defining longitudinal gusseted folds in the panels. The pair of gusseted side panels are expandable about folds therein during cooking of food in the package to enlarge an interior volume of the package. The front panel, the back panel, and the bottom panel form a tube body. A coating is applied onto both an inner surface and an outer surface of the tube body. The coating has a starch-based film having a pre-selected percent by weight of at least one pre-selected starch derivative, a flexibility enhancing agent, and a rheological agent. The at least one starch derivative can include a chemically modified starch, and the coating further can have a scorch resistant agent associated therewith.
An additional embodiment of non-fluorocarbon treated high temperature package according to the present invention is provided having oil and grease resistant properties and includes at least one outer substrate having an inner surface and an outer surface formed of a paper material, and at least one inner substrate also formed of a paper material and having an outer surface thereof laminated to the inner surface of the outer substrate so that the combination of the at least one outer substrate and the at least one inner substrate define a laminated substrate. The laminated substrate further has a front panel, a back panel opposing the front panel, a bottom panel, and a pair of opposing side panels, each extending between the front panel and the back panel. The pair of opposing side panels each has a longitudinal accordion pleat therein defining longitudinal gusseted folds in the panels. The pair of gusseted side panels are expandable about folds therein during cooking of food in the package to enlarge an interior volume of the package. The front panel, the back panel, and the bottom panel form a tube body. A coating is positioned on both an inner surface and an outer surface of the tube body. The coating includes a starch-based film having a pre-selected percent by weight of at least one pre-selected starch derivative, including a chemically modified starch, a flexibility enhancing agent, a rheological agent and a scorch resistant agent.
Embodiments of the non-fluorocarbon treated high temperature package and methods for forming a non-fluorocarbon treated high temperature package that have oil and grease resistant properties and are devoid of fluorocarbons advantageously have significantly reduced brittleness, significantly increased flexibility, and increased resistance to oil and grease staining due to reduced cracking in or around folds in a package substrate. Because an embodiment of a starch-based derivative coating is used for a package of the present invention, the coating advantageously can be used with conventional paper making equipment to form substrates of paper material to enhance the forming of high temperature packaging. Also, in addition to being devoid or substantially devoid fluorocarbons, the high temperature package and methods according to embodiments of the present invention have enhanced scorch resistance properties.
Some of the objects and advantages of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings in which illustrated embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
The packaging material of the high temperature package 20, for example, can be multiply and can preferably include, as illustrated in
In an alternate embodiment as illustrated in
The coating such as shown in
Examples of starch-based films can be found in U.S. Pat. No. 6,528,088 titled “Highly Flexible Starch-Based Films” (“the '088 patent”) and U.S. Pat. No. 6,375,981 titled “Modified Starch As A Replacement For Gelatin In Soft Gel Films And Capsules” (“the '981 patent”), both by Gillenland et al., and both of which are incorporated herein in their entirety. As understood by those skilled in the art, the starch-based films described in the '088 patent and the '981 patent can be utilized as a starting point, and modified as discussed herein by including a flexibility enhancing agent preferably selected from the group as described herein, a rheological agent preferably selected from the group as described above, and a scorch resistant agent preferably selected from the group as described above, to make and use the starch-based derivative coating devoid of fluorocarbons as described herein.
Based on the information from these studies conducted by Applicants, Applicants were able to determine that a starch-based derivative coating can be developed by adding a flexibility enhancing agent and a rheological agent and yet be substantially gel free. Applicants recognized that the existing starch-based derivative can have higher gelling qualities as the concentration of solids is increased. The coating preferably includes a composition having a solids concentration by weight of about 10% to about 35%, more preferably about 20% to about 25%, and is substantially free from a gel formation. The coating preferably has a viscosity in a range of about 65 centipoise to about 156 centipoise. The starch-based material preferably includes a cornstarch. Applicants also recognized that coating inner and outer surfaces of each of the inner and outer substrates can prevent grease, or increase grease holdout, such as generated during cooking or microwave heating of food within a package, from or around a small puncture, fracture, tear, or other opening in the inner substrate from passing through to the outer substrate where staining of the outer substrate would be more readily viewable by the user.
The table of
The packaging 20 may also further include a susceptor adhesive 150, as illustrated in
Alternatively, the packaging 320 may also include, as illustrated in
As illustrated in
In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims.
This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 60/471,607, filed May 19, 2003, titled “Non-Fluorocarbon High Temperature Packaging Having Flexible Starch-Based Film and Method of Producing Same,” which is incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60471607 | May 2003 | US |
