Biodegradable and edible feed packaging materials

Details Biodegradable and edible feed packaging materials Biodegradable and edible feed packaging materials

2003-03-24

2004-04-06

Davis, Robert (Department: 1722)

Plastic article or earthenware shaping or treating: apparatus

Press forming apparatus having opposed press members

Male shaping member and female mold

C425S410000, C425S17480R, C425S422000, C249S112000

Reexamination Certificate

active

06716022

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is broadly concerned with biodegradable and edible packaging composites or containers comprising self-sustaining bodies and formed from a mixture comprising a non-petroleum based, biodegradable adhesive and a quantity of fiber. More particularly, the containers comprise a fiber derived from a fiber source selected from the group consisting of straw (e.g., wheat, rice, barley), corn stalks, sorghum stalks, soybean hulls, peanut hulls or any other fibers derived from grain milling by-products), and mixtures thereof. The adhesive can be protein-based or starch-based, and is preferably formed by modifying a protein, starch, or protein-rich flour with a modifier comprising alkaline materials and/or modifiers having particular functional groups. The resulting mixture has a low moisture content and is molded at high temperatures and pressures to yield a final container having high compressive strengths.
In another aspect of the invention, molding apparatus and corresponding methods are provided for forming complex shapes using composite-type molding materials which are non-flowable under pressure, such as polymer-impregnating cellulosic fibers. The preferred equipment includes generally annular male and female mold sections which present cooperating adjacent surfaces when telescoped together for compression of the non-flowable molding materials so that the materials assume a desired shape for molding. In preferred forms, the mold sections are heated to accelerate curing and hardening of the molding materials.
2. Description of the Prior Art
Livestock gel blocks are currently utilized for supplementing the diets of sheep, horses, and cattle in both feedlot and open grazing conditions. The blocks are formed of gels which are flowable at a temperature of about 80° C. These gels are poured into a container and become rigid upon cooling. The gel blocks have “cold flow properties” meaning that, although they appear to be a solid, the blocks will not retain their shape when subjected to stress (such as from the weight of other blocks or gravity). As a result, the gel blocks are not free-standing and must be in a container at all times. The gels turn into a thick syrup upon absorbing moisture from the air. This syrup is then consumed by the livestock.
Currently available containers for use with gel blocks include half steel drums, plastic tubs, and paper or cardboard containers. Each of these containers has undesirable properties. For example, the steel drums must be either thrown away or recycled after use. Recycling is generally preferred in order to minimize the quantity of waste in landfills and other disposal sites. However, recycling involves additional labor and expense as the drums must be collected and transported back to the feed manufacturer and then reconditioned (i.e., reshaped, cleaned, and sterilized) by the manufacturer before reusing the drum. Likewise, plastic tubs can be discarded or recycled but must undergo the same labor and expense involved in recycling steel drums. Furthermore, the plastic tubs result in the generation of plastic waste which presents a disposal problem for the consumer as well as a liability problem for the manufacturer.
Paper and cardboard containers have been attempted commercially as an alternative to plastic or steel. However, paper and cardboard containers do not perform adequately. One problem with paper and cardboard containers is that they are permeable to moisture at room conditions, thus allowing moisture to contact the gel. This causes the gel to turn into a syrup prematurely which then seeps through the container, making the products difficult to ship and store. Furthermore, these paper and cardboard containers do not easily biodegrade, leaving waste at the feeding site. Finally, the livestock may consume portions of these paper or cardboard containers, presenting a possible danger to the livestock if the paper or card-board is not processed following FDA standards.
U.S. Pat. No. 5,160,368 to Begovich discloses a biodegradable package for fast food comprising a body which is molded from a composition consisting essentially of an admixture of biodegradable natural materials comprising low-protein flour (i.e., about 10-15% by weight protein in the flour) or meal from edible gramineous plants (e.g., corn or sorghum), crushed hay of gramineous plants (e.g., wheat, sorghum, corn, or corncob leaves), a preservative, and a plasticizing agent. However, the '368 package has a high moisture content prior to molding (about 50% by weight moisture), thus resulting in a container that often cracks when molded at the high temperatures and pressures necessary to obtain a strong container. Furthermore, the '368 patent fails to use a strong adhesive which results in a package having inadequate mechanical properties for use in packaging of livestock feed gel blocks (which often weigh 250 lbs. each) and other applications which require a strong container.
Particle boards and similar composites are typically formed from wood chips, sawdust and other wood waste products by mixing such cellulosic materials with a synthetic resin binder and pressing the mixture between flat platens under high pressures and elevated temperatures. While this method is useful for making flat panels, it is not suitable for production of non-planar shapes such as frustoconical half-barrel sections or other complex shapes.
Injection molding processes have long been used to form non-planar objects of varied shapes. However, injection molding is only applicable when the starting molding material is at least somewhat flowable under heat and pressure conditions. Thus, injection molding is inapplicable for use with relatively light, particulate, substantially dry starting materials such as those used to form particle board or the like.
There is a need for biodegradable and edible packaging containers which do not contain cracks or other defects and which have strong mechanical properties, allowing the container to be subjected to stress with little risk of failing. Also, improved molding apparatus and methods which can make use of relatively inexpensive dry particulate starting materials while having the capability of producing non-planar complex objects would represent a significant advance in the art.
SUMMARY OF THE INVENTION
The instant invention provides biodegradable and edible composites having high compressive strengths. Broadly, the composites are in the form of a self-sustaining body formed from a mixture comprising a non-petroleum based, biodegradable adhesive and a quantity of fiber. These composites can be used as containers for livestock gel blocks as well as other applications such as flower and plant containers.
In more detail, the fiber utilized in the inventive composites is derived from a fiber source selected from the group consisting of straw (including wheat, rice, and barley), corn stalks, sorghum stalks, soybean hulls, peanut hulls, and mixtures thereof. While most non-petroleum based, biodegradable adhesives which are capable of forming the high strength composites of the invention are suitable, it is preferred that the adhesive be formed by modifying a starch (e.g., cereal starch and legume starch), protein, protein-rich flour (i.e., soy flour or other flour having at least about 25% by weight protein, and preferably at least about 40% by weight protein), or mixtures thereof with a modifier selected from the group consisting of:
(1) alkaline materials (such as NaOH);
(2) saturated and unsaturated alkali metal C
8
-C
22
(and preferably C
10
-C
18
) sulfate and sulfonate salts;
(3) compounds having the formula I:
 wherein each R is individually selected from the group consisting of H and C
1
-C
4
saturated and unsaturated groups, and X is selected from the group consisting of O, NH, and S; and
(4) mixture of (1), (2), and (3).
The C
1
-C
4
saturated and unsaturated groups refer to alkyl groups (both straight and branched chain) and unsaturated refers to alkenyl and alkynyl

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