Oven safe disposable food container - Patent Review 5317119

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FIELD OF INVENTION

This invention relates to biodegradable articles formed of sand and more particularly to sand-based articles formed using a decomposable binder and methods for forming same.

BACKGROUND

The use of plastic as a container for food sold both in fast food restaurants and in the grocery store is increasing at an alarming rate. There is a great emphasis currently in recycling and minimizing non-biodegradable waste. However, due to the very low cost and the bulky size of plastic and styrofoam food containers, it is not practical to recycle the vast majority of plastic and styrofoam disposable food containers. There is, therefore, a great interest in utilizing food containers which are decomposable and inert in order to minimize the pollution problems resulting from the disposal of food containers in municipal land fills, incineration plants, or road side litter.

Over the years, there has been a significant amount of research to develop an environmentally acceptable disposable container as illustrated in the following patents:

______________________________________ Patent No. Inventor Issue Date ______________________________________ 3,415,402 R. L. Webber December 10, 1968 3,654,064 D. H. E. Laumann April 4, 1972 3,676,401 J. W. Henry July 11, 1972 3,844,987 R. A. Clendinning et al October 29, 1974 3,852,913 R. A. Clendinning et al December 10, 1974 3,867,324 R. A. Clendinning et al February 18, 1975 3,932,319 R. A. Clendinning et al January 13, 1976 4,191,320 L. J. Taylor et al March 4, 1980 4,641,005 O. E. Seiferth February 3, 1987 4,709,808 D. C. Balduff et al December 1, 1987 ______________________________________

These food container patents use a variety of decomposable materials such as various decomposable organic compounds, paperboard, and other biodegradable filler material. While the above listed patents disclose containers which attempt to solve the existing environmental problem, there is yet to be a commercially feasible biodegradable container developed which is competitive from a cost, mechanical structure and consumer acceptance standpoint with the plastics and styrofoam generally used today.

In addition to the environmental problems associated with the disposal of food containers, a problem exists on a smaller scale in disposing of used frangible targets. Frangible targets are commonly used in skeet and trap shooting and are referred to as clay pigeons. Typical clay pigeons are formed of a mixture of a lime based chalk and a pitch, phenyl-resinous bitumen. Broken clay pigeons pose environmental problems as they are not readily decomposable and may be toxic if eaten by animals. Recognizing the environmental problems, there have been efforts in the past to develop non-toxic frangible targets as shown in U.S. Pat. Nos. 4,124,550 and 4,568,087. None of these targets have been readily accepted in the commercial marketplace.

Frangible targets, in order to be competitive in the commercial marketplace, need to be formed of inexpensive materials and exhibit consistent fracture characteristics. Where the targets are to be thrown such as in trap and skeet, it is very important that the targets weight and flight characteristics be consistent as well. It is therefore important that targets should absorb as little moisture as possible as moisture tends to affect both the weight and frangibility.

While frangible targets are quite common, frangible projectiles are virtually unknown. Projectiles for firearms, BB guns, pellet guns and slingshots are typically formed of metal such as lead, copper or steel and in the case of slingshots, glass. The common characteristics of these projectiles is that they tend to ricochet. The ricochet problem is most troublesome when shooting in a confined area. Shooting a BB gun or a slingshot indoors can be particularly dangerous if a stray shot hits a solid object. While lead projectiles have less of a propensity to ricochet particularly at acute angles, lead is expensive and poses environmental hazards.

OBJECTS, FEATURES AND ADVANTAGES OF THE INVENTION

It is an object of the present invention is to provide a method for forming a sand based article having a biodegradable binder for use in a variety of disposable articles.

It is an object of the present invention to provide disposable sand based food containers having a non-toxic biodegradable binder which will rapidly break down once the container has been discarded.

It is an object of the present invention to provide a frangible article for use as a target or a projectile which is biodegradable and non-toxic.

It is also another object of the invention to provide a frangible article with consistent frangibility and resistance to moisture absorption.

Yet another object of the present invention is to provide a projectile suitable for slingshots and the like which can be used indoors without fear of ricocheting.

An advantage of the present invention is that low cost inert or biodegradable materials are used to form the frangible article and consistent frangibility characteristics are achieved thereby.

SUMMARY OF INVENTION

A method of forming a biodegradable article is provided comprising these steps of mixing sand and a decomposable binder together to form a dough-like consistency. The dough-like mix is formed into a sheet and cut into a series of silhouette shapes. In the preferred method, these shapes are formed into three-dimensional objects which are dried to form a rigid, durable article for use as a food container or the like. Preferably, the article is coated with a water resistant sealant to prevent moisture absorption prior to disposal.

A frangible article has been developed for use as a target or a projectile using a mixture of sand and a decomposable binder. The sand binder mixture can be formed as desired and cured to create a rigid, durable article which will fracture into a plurality of dull pieces upon impact. A preferred composition of the binder is a mixture by weight of 20-60% grain flour, 15-30% salt, 1/2-5% petroleum distillate and water.

One embodiment of the invention is a frangible silhouette target formed by mixing of the sand and binder into a dough-like consistency, forming the dough-like mix into a sheet, cutting a series of silhouette shapes and drying the shapes to form rigid, durable targets. Preferably, the target is then coated with a sealant to prevent moisture absorption.

Another alternative embodiment of the invention is a projectile formed of a frangible sand decomposable binder mixture. The projectile is rigid and durable and consistently fractures into a plurality of dull pieces upon impact. The projectile has particularly utility for use as slingshot ammunition.

These objects and novel characteristics of the invention will become further apparent from a review of the accompanying drawings and detailed description of the preferred embodiment.

BRIEF BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a sheet target mounted on a pellet trap having a plurality of frangible silhouettes affixed thereto;

FIG. 2 is a cross-sectional view taken along lines 2--2 in FIG. 1;

FIG. 3 is a cross-sectional side view of an alternative embodiment of the invention;

FIG. 4 is a perspective view of yet another embodiment of the invention;

FIG. 5 is a cross-sectional side view taken along lines 5--5 in FIG. 4;

FIG. 6 is respective view of a silhouette target held by a free-standing base;

FIG. 7 is a cross-sectional side elevation of a bullet trap holding a frangible silhouette target;

FIG. 8 is a side view representing a frangible projectile striking the metallic silhouette;

FIG. 9 is a block diagram showing a method of manufacturing frangible articles;

FIG. 10 is a perspective view of a alternative embodiment of the invention showing frangible targets mounted on fan-fold paper used in conjunction with a bullet trap having an automatic target advance mechanism;

FIG. 11 is block diagram illustrating a method of manufacturing a three-dimensional sand based article having a biodegradable filler;

FIG. 12 is a block diagram illustrating a method of forming and filling sand based containers having a biodegradable binder for use in food packaging;

FIG. 13 is a perspective view of a multi-compartment food tray formed utilizing the present invention;

FIG. 14 is a cup-like container formed utilizing the present invention; and

FIG. 15 is a perspective view of a filled food container formed utilizing the present invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT

Frangible Article

Referring generally to the drawings, a number of alternative embodiments of a frangible article for use as a target or a projectile are shown. FIGS. 1-7 and 10 show various silhouette targets designed for use with BB, pellet or small caliber guns. The targets are highly frangible and fracture upon impact by a projectile. The target fragments are biodegradable and alleviate the environmental problems posed by many other frangible targets.

A preferred target composition is a mixture of clean screened sand and an organic grain base binder. The sand when mixed with a binder forms a dough-like mix which can then formed into various shapes and dried in an oven. The preferred sand is screened to remove both large and small granules. Preferably, the sand will be screened to remove substantially all of the granules outside of the 0.1 to 0.5 millimeter grain size range. The grain size is determined optically measuring the maximum cordal length of the grain. Sand outside of the range will work, however, very fine sand causes drying time to be unnecessarily long and the use of coarse sand results in a crumbly mixture which is difficult to process.

An example of a preferred binder is a mixture by weight of: 20-60% grain flour, 5-30% salt, 1/2-5% lubricant and water. Preferably, fungicide such as borax which would also be included representing approximately 1 to 2% by weight of the binder mixture. A drying agent such as alum or the like may also be added to improve the workability and texture of the binder mixture. The binder and sand are mixed together in sufficient quantities to achieve a dough-like mixture. Sufficient binder must be added so that the mixture is not too crumbly and sufficient sand must be present to minimize the drying time and the amount of shrinkage. Wheat flour is preferred for cost reasons but other grain flours or starches work satisfactorily. A light oil such as petroleum distillate or vegetable oil preferably acts as the lubricant and prevents the mixture from becoming sticky. Kerosene or other light petroleum distillates satisfactorily perform this function. The preferred salt has the grain size of table salt so as to quickly dissolve.

Once the sand and binder have been blended together, it is next formed into sheets using conventional rolling or extruding techniques. The sheet is then cut-up using a die or the like to create target preforms. The process is somewhat similar to making cookies with a cookie cutter. The shaped preforms are then dried using conventional convection oven batch or conveyor design. Alternatively, the preforms may be dried in a hot press operation where a heated die set will not only dry the preform but impart shape thereto. Other drying techniques are also possible such as dielectric heating. Care should be taken so that the drying rate is sufficiently slow to enable moisture to escape from the drying article without forming internal steam pockets which would fracture or weaken the article.

Once dried and cooled, the targets may be handled. The finished targets will be hard and durable but will readily fracture upon impact. The targets, however, are susceptible to moisture absorption and should be