COATED BOX WITH ANTI-GREASY FINGERPRINT COATING

Abstract

A coated box with anti-stain coating on portions of exterior surfaces of the coated box, which also has uncoated exterior surfaces to which a water-based adhesive is applied to adhere to portions of an interior facing surface to form a box shape that includes folds at creases at scored lines.

Claims

1. A container, comprising: paperboard having scored lines and being creased at the scored lines to fold into a box shape that has exterior facing surfaces and interior facing surfaces; anti-staining means for preventing staining from grease and water of portions of the exterior facing surface of the paperboard, said anti-staining means including a water-based coating on the portions of the exterior facing surfaces to provide a slick surface texture and a glazed appearance, the exterior facing surfaces also having uncoated regions left uncoated which lack the water-based coating; and a water-based adhesive adhering the uncoated regions of the exterior facing surfaces to portions of the interior facing surfaces that are in alignment therewith with the paperboard folded into the box shape.

2. The container of claim 1, wherein the paperboard has post-consumer waste content paper selected from the group consisting of mixed paper, retired books, magazines, newspaper, corrugated boxes, and any combination thereof.

3. The container of claim 1, wherein the water-based coating includes a primer coat layer and an overcoat layer that is on the primer coat layer, the overcoat layer having a higher volume of a same coating material as that of the primer coat layer.

4. The container of claim 1, wherein the paperboard has treated fibers having sufficient potency at time of treatment to kill off bacteria residing in the fibers.

5. The container of claim 1, further comprising: a petroleum-based coating on the interior facing surfaces to provide an oily surface texture and a glossy appearance, the slick surface texture and glazed appearance from the water-based coating of the exterior facing surfaces being less light reflective than the oily surface texture and glossy appearance of the interior facing surfaces.

6. A method of container manufacture, comprising providing paperboard with scored lines being creased at the scored lines to fold into a box shape that has exterior facing surfaces and interior facing surfaces; preventing staining from grease and water of portions of the exterior facing surface of the paperboard with anti-staining means that includes applying a water-based coating on the portions of the exterior facing surfaces to provide a slick surface texture and a glazed appearance, the exterior facing surfaces also having uncoated regions left uncoated which lack the water-based coating; and adhering a water-based adhesive to the uncoated regions of the exterior facing surfaces to portions of the interior facing surfaces that are in alignment therewith with the paperboard folded into the box shape.

7. The method of claim 6, further comprising the step of: providing the paperboard that has post-consumer waste content paper selected from the group consisting of mixed paper, retired books, magazines, newspaper, corrugated boxes, and any combination thereof.

8. The method of claim 6, further comprising: applying the water-based coating as a primer coat layer followed by an overcoat layer applied to the primer coat layer, the overcoat layer having a higher volume of a same coating material as that of the primer coat layer.

9. The method of claim 6, further comprising: providing the paperboard with treated fibers having sufficient potency at time of treatment to kill off bacteria residing in the fibers.

10. The method of claim 6, further comprising: applying a petroleum-based coating on the interior facing surfaces to provide an oily surface texture and a glossy appearance, the slick surface texture and glazed appearance from the water-based coating of the exterior facing surfaces being less light reflective than the oily surface texture and glossy appearance of the interior facing surfaces.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0081] For a better understanding of the present invention, reference is made to the following description and accompanying drawings, while the scope of the invention is set forth in the appended claims.

[0082] FIG. 1 shows the effect of water on an uncoated surface of paperboard in accordance with the prior art.

[0083] FIG. 2 shows the effect of water on a coated surface of paperboard in accordance with the invention, but also applies to the effect of oil on the coated surface.

[0084] FIG. 3 shows the effect of water seeping through to the opposite surface of the uncoated surface of paperboard of FIG. 1.

[0085] FIG. 4 shows the effect of the water over time on the uncoated surface of the paperboard of FIG. 1 as well as the effect of oil applied to another region of the uncoated surface of the paperboard by lightly pressing the oil against it with a finger.

[0086] FIG. 5 shows the effect of a greasy fingerprint applied on the coated surface of paperboard of FIG. 2. in accordance with the invention.

[0087] FIG. 6 shows the effect of water and oil on an uncoated surface of a paperboard box in accordance with the prior art,

[0088] FIG. 7 shows the effect of water and oil a coated surface if a paperboard box in accordance with the invention.

[0089] FIG. 8 shows a portion of the surface having an uncoated portion to which glue is applied on the same surface that is coated in accordance with that of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0090] The formation of a folding carton is conventional, for instance, as discussed in the Discussion of Related Art found in this patent application such as with respect to an article entitled FOLDING CARTONS, published online under the heading Packaging technology at http://packagingtech.net/56-folding-cartons.html?newsid=56.

[0091] FIGS. 1-8 are a series of photographs that are believed to be self-explanatory in showing the effect of depositing water 12 and oil or a greasy fingerprint 16 onto uncoated paperboard 10 and onto coated paperboard 20. In the case of the uncoated paperboard 10, a deposit of water 10 or oil 16 on its surface stains the topside of the paperboard as can be seen by the water stain 14 in FIGS. 1 and 4 the greasy oil stain 16 in FIG. 4. If there is a sufficient quantity of water deposited, for instance, the water seeps into pores of the paperboard to stain the underside of the paperboard as well as shown by the water stain 14 in FIG. 3. Such contrasts with the hydrophobic effect to water and oil deposited that the coated paperboard in accordance with the invention possesses (See FIGS. 2, 5 and 7) in which the staining is either nonexistent or considerably less noticeable or less evident than in the case of the water stain 14 of FIGS. 1 and 4 or the greasy fingerprint stain 16 of FIG. 4. Indeed, the water stain is non-existent in FIG. 2 and the greasy fingerprint stain 16 of FIG. 5 is much lighter than for the case of FIG. 4 and may even be considered to blend into the neighboring background of the exterior surface 20 so as to be less noticeable to the eye that the darkened stain 16 of FIG. 4.

[0092] In addition, wiping the coated surface of the exterior surface 20 with a cloth or paper towel essentially removes the water of FIG. 2 or the grease of FIG. 5, which did little if any penetration of the pores in the paperboard to cause staining, unlike the case for the uncoated box of FIGS. 1 and 4 in which the water or grease stain penetrates the paperboard pores of the uncoated box to cause dark staining.

[0093] In accordance with the invention, the paperboard fibers that are used in the manufacture of paperboard are treated to kill off any lingering bacteria residing in them in a manner that is approved by the United States Food and Drug Administration (FDA) for use on a carton or packaging that is to contain food. Nevertheless, the paperboard is not resistant to staining even though its fibers may have been so treated. Such treatment does not prevent unsightly staining from arising when the paperboard is handled by one's greasy fingers as may occur during food packaging at a take-out establishment. This is because the hold-out, which is the resistance of fibers to fluid absorption, is not present for such fibers despite their treatment.

[0094] A grease resistance coating could be applied to the paperboard fibers themselves at the time of manufacture. Such a coating would improve the hold-out for such fibers. Even so, the present inventor has found that paperboard boxes made from such grease-resistant coated fibers still stain from greasy fingerprints.

[0095] A sheet of paperboard has two faces. Once the sheet is folded into a box as in FIGS. 6 and 7, one of the faces will have interior facing surfaces 11, 21 and the other face will have exterior facing surfaces 10, 20 when the box is closed.

[0096] In accordance with the invention, the interior facing surfaces 21 (see FIG. 7) are coated in a conventional manner such as with the MEYERCOTE grease-resistant coating that is petroleum based and thus will provide an oily surface texture with a glossy appearance. Portions of the exterior surfaces 20 (See FIGS. 2 and 5) will be coated in accordance with a water-based barrier coating with 35% to 45% solid suspension to have a slick surface texture that is not oily and a glazed appearance that has less light reflective shine than glossy. Such a water-based barrier coating is available in drums to the trade by requesting the water-based barrier coating under the tradename MEYERKOTE PLUS PASTRY COATING from Miami Valley Paper Company division of Mafcote Inc. The remaining portions 22 of the exterior surfaces 20 will be left uncoated since a water-based adhesive will be applied to them (see FIG. 8).

[0097] In order to apply the water-based coating, a two-station coating application with a conventional central impression flexographic printing press is used to coat the portions of the exterior facing surfaces. Each pass through the conventional central impression flexographic press entails passing the coated paperboard through a heated, forced air chamber that blooms the coating followed by letting the coating set on the surface of the paperboard without the heat and forced air being applied. The heating is to a temperature above that of room temperature, such as to 120 degrees Fahrenheit.

[0098] One station (of the conventional central impression flexographic printing press) carries a normal surfactant volume for the primer coat and another station carries more in volume over that carried by the first station. During operation, the conventional central impression flexographic printing press first sizes the sheet of uncoated paperboard to be coated and applies the primer coat from one station.

[0099] At another station, the primer coated paperboard is coated again with an overcoat that has a higher volume of the same coating material as the primer coat, such as more volume. Afterward, the finished sheet goes through a heating process that sets both coating applications, which blooms out solids from the coating composition to create a tight surface tension and closes the sheet's surface to render it hydrophobic, thereby giving it the desired resistance to stain and thus protects against staining from greasy fingerprints.

[0100] To achieve blooming, chemical additives in the water-based coating are heated above room temperature such as at 120 degrees Fahrenheit to tighten the surface tension sufficient for surfactant sealing and to repel liquidrendering the surface hydrophobic. Without such heat, no blooming occursthe present inventor has found that such does not prevent stains from greasy fingerprints. Further, the present inventor found that after the primer coat is applied, the paperboard is still open in its ability to absorb moisture, which is why the higher volume overcoat needs to be provided as well to create the proper surface tension that seals the paperboard against absorbing fluid and thus rendering it resistant to staining from greasy fingerprints.

[0101] Unlike the case for uncoated paperboard, the water-based coated paperboard after blooming appears glazed in appearance on the surface and has a slick and smooth surface texture. The slick surface texture is not oily. The glazed appearance is not as shiny as the glossy appearance that results from a petroleum-based coating.

[0102] The end result is a product that is 100% recycled, 100% recyclable, 85% post-consumer waste content (PCW) and is 100% compostable within 90 days in a properly managed landfill.

[0103] The conventional central impression flexographic printing press enables one to register selected portions of the paperboard to leave uncoated. Such regions are chosen where glue is to be applied to secure the box shape. The glue is preferably a water-based glue that has relatively low volatile organic compounds, unlike the case for petroleum-based glue.

[0104] While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various changes and modifications may be made without departing from the scope of the present invention.