CN1342051A - Food container having cut resistance surface - Google Patents

Abstract

A food container has a first user-facing surface and a second surface. The cut-resistant exterior facing is juxtaposed and preferably coincident with the first surface. The outer facing consists of a single ply of particulate material. The particle size of the particulate material is at least 5 microns, and preferably 50-200 microns. The particulate material preferably has a Mohs hardness of at least 3.

Description

Food containers with cut-resistant surfaces

Field of Invention

The present invention relates to food containers, particularly food containers having a user-facing surface that provides improved cut resistance.

Background of the Invention

Disposable food containers are well known in the art. Disposable food containers include common paper plates, bowls, clamshells, saucers, and more.

Considerable attention has been given in the art to the fabrication, molding and deformation of these food containers beyond a single plane. A blank is produced in the deformation process. The blank is inserted between the mating platens and compressed. The perimeter of the blank will have radial grooves. Radial grooves are used to accumulate material deformed by the platen. Exemplary techniques are included in the following patents: US Patent 3,033,434, issued May 8, 1962 to Carson; US Patent 4,026,458 issued May 31, 1977 to Morris et al; Patent 4,606,496; US Patent 4,609,140 issued September 2, 1986 to Vanhandel et al; US Patent 4,721,500 issued January 26, 1988 to Van handel et al; US Patent 5,230,939 issued July 27, 1993 to Baum et al; 1994 US Patent 5,326,020 issued Jul. 5 to Cheshire et al. The contents of the above patents are incorporated herein by reference.

However, the above-mentioned attempts in the art have several disadvantages. As illustrated by the various attempts to improve the stiffness and stability of food containers, prior art attempts have failed to provide food containers of sufficient strength. The lack of strength causes the food container to overflow when the food container is filled with too much food, or unduly restricts the amount of food that can be placed in the food container at a given time.

Attempts have also been made in the art to improve the stiffness of such food containers. For example, food containers are known in the art having a bottom wall, a side wall surrounding the bottom wall and disposed radially outwardly of the bottom wall, and a rim surrounding the side wall and disposed radially outwardly of the side wall. Attempts have also been made in the art with food containers having densified regions on the side walls. Similarly, food containers having closely spaced circumferentially spaced regions of annular portions extending radially across the rim are also known. These attempts in the art claim to provide bending resistance throughout the structure. Examples of these attempts are found in U.S. Patent 4,606,496 issued August 19, 1986 to Marx et al. and U.S. Patent 4,609,140 issued September 2, 1986 to Van Handel et al.

Prior art food containers have coatings to improve resistance to penetration by liquids such as grease and the like. Coatings can also be used to provide cut resistance, gloss, ink absorption, etc. to the finished product. Examples of these attempts include US Patent 5,776,619, issued July 7,1998 to Shanton. Shanton discloses a coated paperboard having two coats, a base coat and a top coat. Each coating includes polymerized latex and particulate pigments. The top coat had a compound of about 90 parts kaolin, about 80% of which had a particle size of less than 2 microns. In addition, US Patent 5,709,913, issued to Andersen et al. on January 20, 1988, in Example 112, discloses inorganically filled paper trays that are said to be more rigid than conventional paper trays.

Another attempt in this field is described in US Patent 5,635,279, issued June 3, 1997 to Ma et al. Ma et al. disclose paperboard having a polymer matrix/wax/pigment mixture as an aqueous composition suitable for corrugated carton construction. Coatings are composed of pigments including natural and synthetic silicates, bentonite, kaolin and other clays. US Patent 5,494,716 issued February 27, 1996 to Seung et al. discloses a food pan having an aqueous coating with a styrene/vinyl latex or other agent. US Patent 5,334,449 issued August 2, 1994 to Bergmann discloses a primary coating with a mixture of kaolin, calcium carbonate, casien and butadiene-styrene latex. US Patent 5,100,472 issued March 31, 1992 to Fugitt et al. discloses a paper coating containing deionized clay or calcium carbonate.

Attempts to improve wear resistance using particulate materials have been made in non-similar fields. For example, U.S. Patent 5,558,906 issued September 24, 1996 to Albrinck et al. discloses a decorative laminate having a wear-resistant material comprising alumina particles having a particle size of about 25 microns and about 3 microns, the ratio of which is 2 : 1 ratio.

Additionally, mineral pigments such as titanium oxide, water and particulate fillers such as kaolin are used as opacifiers in non-similar fields such as tissue paper. Examples are included in the following patents, which have common assignees with this invention: US Patent 4,952,278 issued August 28, 1990 to Gregory et al; US Patent 5,611,890 issued March 18, 1997 to Vinson et al; September 1997 US Patent 5,672,429 issued to Vinson et al. on the 30th. The disclosures of the above patents are incorporated herein by reference. Additionally, fillers and cationic starches are taught in non-similar fields such as newsprint production, see US Patent 5,670,021, issued September 23, 1997 to Owens.

Accordingly, the present invention provides a food container having a cut-resistant surface that is easier to handle and more acceptable to consumers than has been attempted in the prior art. In particular, the present invention provides a food container with a cut-resistant surface that not only improves resistance to accidental cuts and penetration of liquids such as grease, but also provides better touch.

Invention Summary

The present invention is a food container. The food container has a first user-facing surface and a second surface opposite the first surface. The food container has an outer facing comprising cut-resistant particles juxtaposed and preferably coincident with the first surface. The outer facing consists of a single ply of particulate material. The particulate material has a Mohs hardness of at least 3, and preferably at least 7.

The particle size of the particulate material is at least 5 microns, and preferably at least 10 microns.

A brief description of the drawings

Fig. 1 is the perspective view of the food container of the present invention;

Fig. 2 is a partial sectional view taken along line 2-2 in Fig. 1;

A detailed description of the invention

Referring to Figures 1-2, the food container 10 of the present invention may comprise a plate, bowl, saucer, clamshell container, cutting board, or any other configuration known in the art.

The food container 10 of the present invention generally includes a concave first surface 11 and a convex second surface 12 . The concave first surface 11 of the food container 10 is the side which in use normally faces the user. The convex side of the food container 10 is normally in use away from the user and sits against a horizontal surface such as a table.

The food container 10 thus comprises a first user-facing surface and a second surface 12 opposite the first surface 11 . The food container 10 also has a cut resistant outer facing 32 juxtaposed and preferably coincident with the first surface 11. The cut resistant outer facing 32 includes particulate material 34 disposed in one ply. The particulate material 34 of the cut resistant outer facing 32 is disposed on and supported by the substrate 30 .

The food container 10 includes a central region 14 and a surrounding perimeter 16 . The central region 14 and perimeter 16 are preferably disposed on two different planes, although a flat food container 10 is also contemplated as a less preferred embodiment of the present invention. The flat food container 10 can be used, for example, as a food dish or cutting board.

The central zone 14 defines the XY plane of the food container 10 . The Z direction of the food container 10 is perpendicular to the XY plane. The food container 10 has a transition region 20 from the central region 14 to the perimeter 16 . Perimeter 16 is spaced from central region 14 in the Z direction, or food container 10 may be flat, as described above. In normal use, the perimeter 16 is elevated relative to the central region 14 . The central region 14 of the food container 10 defines a first portion of the food container 10 . Similarly, the perimeter 16 of the food container 10 defines the second portion of the food container 10 .

Therefore, the food container 10 is preferably multi-planar. Multi-plane means that different parts of the food container 10 are located on different planes. One example of the multi-planarity of the food container 10 of the present invention is shown by the central region 14 and the perimeter 16 of the food container 10 . The central region 14 and perimeter 16 of the food container 10 are spaced apart in the Z-direction such that the food container 10 appears multi-planar.

What is needed is to accommodate the buildup of material that occurs as the food container 10 is formed. Pleats and creases are commonly used for this purpose, as is known in the art. Various folds and creases are conceivable, especially cumulative creases in radial orientation.

The central region 14 or perimeter 16 need not be parallel to the XY plane or generally planar. For example, bowls with a generally concave bottom are suitable for application of the present invention. The distance from the bottom surface of the central region 14 (taken when the food container 10 is in its normal use and generally horizontal position) to the top surface of the perimeter 16 is referred to as the Z-direction depth 19 of the food container 10. If there are different depths in different parts of the food container 10, the Z-depth takes the largest Z-distance.

The boundary and shape of the perimeter 16 is defined by the edge 18 of the food container 10 . It will be appreciated that the dimensions and relative proportions of the perimeter 16 and intermediate region 14 of the food container 10 may vary depending on the precise dimensions and intended use of the food container 10 . While a circular food container 10 is considered, one of ordinary skill in the art will recognize that a suitable shape and depth for the food container 10 can be selected for the purposes of the present invention, and the present invention is not limited. Other suitable shapes include square, rectangular, oval, various polygons, and the like.

The substrate 30 of the food container 10 may include at least two plies, a first ply and a second ply. The second sheet may be smaller than the first sheet such that at least a portion of the food container 10 is free of the second sheet. The second sheet and the first sheet may be concentric. It will be appreciated that alternative embodiments (not shown) of the food container 10 may also include 3 or more sheets.

In a particularly preferred embodiment, the food container 10 comprises a sheet of rigid material, particularly a material for supporting the juxtaposition and preferably coincidence of the cut-resistant outer surface 32 with the user-facing surface of the food container 10 . Suitable rigid materials include foam, plastic and various other synthetic materials. The food container 10 is preferably made of cellulose and may be made of kraft paper, stiff bleached sulfuric acid paper (SBS), or layers of various papermaking fibers including regenerated cellulose. The food container 10 may also be molded from a wood pulp slurry or pressed from a blank between mating platens. These manufacturing methods are well known in the art.

The outer cover 32 has the ability to resist the penetration of hot fatty food into the base 30 of the food container 10 . In addition, the outer surface 32 provides a pleasant tactile sensation when a user touches the first surface 11 of the food container 10 or cuts food thereon with a cutlery such as a knife.

Those of ordinary skill in the art will recognize that particulate material 34 is particularly preferred for the exterior facing 32 . A material with discrete and dispersed particles makes the finish hard and cut-resistant without being brittle. This combination allows the food container 10 to be handled, shipped, etc. without breaking, crumbling, delaminating or chipping the surface of the outer cover 32 during normal shipping and use.

It is important that the first surface 11 of the food container 10 is hard and pliable, not hard and brittle. This fact also makes the first surface 11 of the food container 10 resistant to cutting. As used herein, a surface may be considered "cut resistant" if it allows the user to apply normal pressure during food cooking and other food preparation without generally penetrating through the base 30 of the food container 10 . It is also important that the first surface 11 has the right tactile feel directly against the fingertips and as it passes through the various cutlery.

Preferably, the particulate material 34 making up the outer skin 32 has a Mohs hardness of at least 3, preferably at least 7, even close to or greater than 9 on the Mohs scale. A Mohs hardness of between 6.5 and 7.5 was found to be suitable for the food container 10 of the claimed invention. The particulate material 34 of the outer facing 32 has a Mohs hardness scale (measured on a scale of 1 to 10 talc to diamond) as described in various reference manuals, such as 4- pp. 132 to 4-139, 12-93 to 12-97, and 12-205 to 12-206, which apply here by reference. Of course, the hardness of the particulate material 34 making up the outer facing 32 is determined prior to incorporation of the particulate material 34 into or onto the substrate 30 of the food container 10 .

By providing the granular material 34 with the above-mentioned hardness, a food container 10 having an appropriate and pleasant touch is obtained. Such hardness allows the user to use a sharp knife to cut food on the food container 10 without unpleasant things like meat juices or roast juices penetrating into the food container 10 when the knife cuts through the food container 10 .

Furthermore, it was unexpectedly found that the particulate material 34 has a preferred particle size. The preferred particle size is necessary to impart a harsh touch without being unpleasant. Therefore, the user does not have to worry about cutting the food on this food container 10 with a sharp knife or other utensils.

The particulate material 34 comprising the outer facing 32 has a particle size of at least 5 microns, preferably 10 microns. The size of the particulate material 34 is 20 to 200 microns, and possibly in the range of 50 to 200 microns. Particle size was measured with an L3P Sonic Sifter available from VWR Scientific Products Corp., Cat. No. 57353-035.

The particulate material 34 comprising the outer facing 32 may be a mixture or mixtures of mineral and other types of particulates known and commercially available in the art. For example, various particles include aluminum, silicon, carbonates, oxides, carbides, nitrides, bromides, hard metals, cemented carbides, hard elements. If carbide is selected, suitable carbides include tantalum carbide, titanium carbide, zirconium carbide, beryllium carbide or silicon carbide (corundum). If borides are selected, suitable borides include aluminum boride, tantalum boride, zinc boride, titanium boride. Boron can also be used. If nitrides are used, suitable nitrides include aluminum nitride, zinc nitride and titanium nitride. Hard metal alloys including, for example, iron, steel, and non-ferrous metals may be used as particulate material 34 . Ceramics such as porcelain, especially porcelain-like ceramic particulate material 34 have been found to be particularly suitable. More particularly, aluminum oxide (corundum), silicon oxide (quartz), calcium carbonate, potassium aluminum silicate, feldspar are also suitable. Silica, calcium carbonate, and alumina are commercially available from the J.T. Baker Company, a division of Mallincroft Baker, Inc., of Phillipsburg, NJ, catalog numbers JT3405, JT1301, and JT0536, respectively.

The particulate material 34 may also include clay. Kaolin has been found to be particularly suitable. A suitable kaolin clay is commercially available from the J.T. Baker Company of Phillipsburg, NJ, catalog number JT2242.

A suitable mixture for the outer finish 32 has been found to be 80% kaolin and 20% alumina. Another suitable mixture is 80% kaolin and 20% calcium carbonate. The percentages described herein are by weight unless otherwise stated.

Particulate material 34, including any type of clay, can be added to the water-based resin to form the coating. Acrylic resins are particularly preferred. A suitable coating may have 50-90% resin, with 10% to 50% particulate material 34 mixed therein.

Suitable additions of the particulate material 34 forming the outer covering 32 of the first surface 11 of the food container 10 are about 0.5 to 100 grams per square meter, preferably about 1 to 50 grams per square meter. A circular food container 10 having a finished diameter of about 22.9 cm and a particulate material 34 comprising the outer cover 32 of 0.1 to 2 grams was found suitable.

Desirably, the particulate material 34, including any resin or other carrier used, is applied to the substrate 30 of the food container 10 as a single ply. The advantages of a single ply tablet over the prior art teachings of a bilayer ply are: more precise control of dosing, one application operation, and can be supplied in a dry operation for mass production. In contrast, prior art teachings of bilayer tablets require two charges of raw material, two processes for applying particulate material 34 to substrate 30 .

The coating that ultimately makes up the exterior finish 32 may be applied to the base 30 of the horizontal container 10 after it has been formed. Coatings comprising particulate material 34 may be applied by knife coating, printing, spraying, and the like as is known in the art. If blade coating is used, the hardness of the blade must be at least as hard as the particulate material 34 . Preferably, the particle mixture is applied to substrate 30 using an air knife coating method. Preferably, the substrate 30 of the food container 10 cannot be submerged in the coating so that the second surface 12 of the food container 10 remains uncoated.

Those of ordinary skill in the art will recognize that many variations are possible. For example, particulate material 34 may be applied in a gradient. The gradient is preferably such that the added amount is larger near the center of the food container 10 where cutting generally occurs more frequently during use. Lesser amounts of particulate material 34 may be applied to the exposed sides and perimeter 16 of the food container, which generally function to contain food within the perimeter 16 of the food container 10 . This preserves the particulate material 34 and concentrates the particulate material 34 in areas that typically experience the greatest wear in use. This arrangement creates a Z-direction gradient with increasing density toward the center of the food container 10 and decreasing density toward the edges of the food container 10 .

Alternatively, the particulate material 34 varies in an XY pattern between regions of the first surface 11 with particulate material 34 and regions without particulate material 34 . The particulate material 34 may be applied, for example, in a checkerboard pattern or in strips. Suitable patterns of strips include concentric rings, radial lines (straight or spiral), parallel lines, and the like. This arrangement provides the advantage that the food container 10 is flexible in areas without particulate material 34 and rigid in areas with particulate material 34 . Thus, a food container 10 having a cut-resistant outer facing 32 is obtained.

Optionally, the outer finish 32 may have at least one protective coating (not shown). The protective coating protects the particulate material 34 and the outer finish 32 from detaching from the food container 10 substrate. Furthermore, the protective coating defines and provides a smoother first surface 11 . It is preferred that the protective coating does not provide a too smooth first surface 11, otherwise, a suitable tactile feel cannot be obtained.

The protective coating can include acrylics. Preferably, the acrylic resin is relatively transparent or translucent, so as to obtain an aesthetically pleasing first surface 11 . The protective coating can be applied by printing, spraying, dipping, knife coating, air knife coating, and the like as known in the art.

Claims (10)

1. food containers, described food containers have first towards user surface and with its opposing second surface, described food containers has and the juxtaposed external facing of described first surface, it is characterized in that, described external facing is made of the single synusia of granular materials.

2. food containers as claimed in claim 1 is characterized in that the Mohs' hardness of described granular materials is approximately 3 at least.

3. as claim 1 and 2 described food containers, it is characterized in that described external facing also comprises resin.

4. as claim 1,2 and 3 described food containers, it is characterized in that described external facing also comprises clay.

5. food containers, described food containers have first towards user surface and with its opposing second surface, described food containers has and the juxtaposed external facing of described first surface, it is characterized in that, described external facing comprises that particle size is at least 5 microns granular materials.

6. food containers as claimed in claim 5 is characterized in that, described granular materials is in 20 to 200 microns scope.

7. as claim 1,2,3,4,5 and 6 described food containers, it is characterized in that described granular materials is selected from following material group: aluminium, silicon, carbonate, oxide, silicate, carbide, nitride, boride, hard metal, carbide alloy, and their mixture.

8. food containers, described food containers have first towards user surface and with its opposing second surface, it is the center on border that described food containers also has with the periphery, described food containers has and the juxtaposed external facing of described first surface, described external facing comprises granular materials, it is characterized in that described granular materials becomes the gradient setting, near the granular materials the food containers center is more than the granular materials at the food containers periphery.

9. food containers as claimed in claim 8 is characterized in that, comprise the center and around periphery, described around periphery be arranged on two different planes with described center and link to each other by transition region.

10. food containers, described food containers have first towards user surface and with its opposing second surface, described food containers has with described first surface and puts and comprise the external facing of granular materials, it is characterized in that described first surface has zone that contains described granular materials and the zone that does not contain described granular materials.

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