This invention relates to packaging material, and more particularly to a packaging material which, upon being disposed, will degrade over a relatively brief period of time once exposed to the elements--i.e., water, bacteria, fungi, etc. More particularly this invention relates to an improved process for producing such packaging material.
In recent years, it has become increasingly desirable for both individuals and businesses to decrease their threat to the environment by recycling solid wastes such as paper, certain plastics, glass and aluminum. In an effort to further reduce the volume of solid waste, businesses and individuals may also elect to substitute recyclable materials, such as paper and cardboard, for the non-biodegradable, non-recyclable polymers currently being used as packaging materials. Unfortunately, this option is seldom chosen due to the obvious increase in costs, and as a result, continued use of plastics and other non-biodegradable polymers is becoming a most serious burden to not only waste disposers and landfills, but more importantly, to our planet as a whole.
Numerous efforts have been made to alleviate this growing problem through the development of biodegradable materials which can be substituted in place of the heretofore non-biodegradable polymers so often employed for packaging materials such as wrapping films, containers, fillers, and the like. U.S. Pat. No. 3,921,333, for example, suggests that the problem can be at least partially solved by using synthetic plastic materials such as thermoplastic polymers which are biodegradable.
The U.S. Pat. No. 4,312,979 discloses various methods for preparing polysaccharides by extracellular cultivation from the genus Pseudonomas in a nutrient medium. Although the patent does not disclose or teach the production of a packaging material, it does suggest that polysaccharides can be used as moldable materials for biodegradable films, as well as for other purposes.
U.S. Pat. No. 4,472,542 discloses a hydrogel produced as a result of dissolving a gel in a polyvinyl alcohol and partially dehydrating the gel solution by means of a freeze-drying process. The resulting product, however, remains as a semisolid gel and is therefore unsuitable for use as a packaging material. In my prior U.S. Pat. No. 4,992,220, I disclosed a novel method for producing biodegradable packaging material in any molded shape or form. This process involved forming a gel mold by dispersing a natural polysaccharide extract in water, freezing the molded gel, and then freeze-drying the molded gel to produce a lightweight material similar in consistency to urethane foam. This method, however, is subject to excessive costs due to separate freezing and freeze-drying stages, operation of their separate apparatus and handling therebetween.
Accordingly, one object of this invention is to provide an improved method of producing a biodegradable packaging material from a gelable plant and/or animal extract.
Another object of this invention is to provide a less expensive method of producing a biodegradable packaging material from a gelable plant and/or animal extract.
Also, a more specific object of this invention is to provide a less costly biodegradable packaging material which may offer a more desirable alternative to non-biodegradable packaging materials.
Other objects of this invention will be apparent hereinafter from the specification and from the recital of the appended claims.