Stock material or miscellaneous articles – Composite – Of carbohydrate
Reexamination Certificate
2000-10-30
2002-02-26
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of carbohydrate
C524S009000, C524S013000, C524S014000, C524S058000, C524S086000, C524S127000, C428S402000
Reexamination Certificate
active
06350531
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a biodegradable plastic molded article and more particularly to a biodegradable plastic molded article with a high biodegradation rate.
2. Background Art
The demand for biodegradable plastics which degrade in the environment increases due to environmental problems faced by the society. Biodegradable plastics which have already been developed are classified into the following four categories, which partially overlap each other.
(a) naturally-occurring polymers consisting of polysaccharides such as starch,
(b) microbial polyesters using the biological activities of microorganisms (polyhydroxyalkanoates and the like),
(c) usual plastics added with degradation accelerators, that is, mixtures having accelerated degradation characteristics, and
(d) chemosynthetic compounds including aliphatic polyesters and the like.
The biodegradable plastics have been used as raw materials for throw-away articles or used for articles which do not need to usually carry heavy loads based on the individual characteristics of these different materials. Examples of the above-mentioned application include agricultural articles such as films, sheets, fastening screws, planting pots, and sacks; daily necessities and table wares such as trays, cases, and straws; certain medical articles; and sporting goods. However, applicability of the biodegradable plastics is still restrictive. The influence thereof on the overall plastic industry is also restricted.
The review of “the present state of technology” concerning macromolecules which degrade in the environment is shown in “Encyclopedia of Chemical Technology, the fourth edition” Vol. 19, 968-1004, published by John Wiley and Sons Corporation, 1996. The above whole teaching is hereby incorporated into the present description by reference. In addition, the review of the manufacturing method and the test method utilized at present is shown in “Encyclopedia of Chemical Technology, the fourth edition” Vol. 19, 290-347, published by John Wiley and Sons Corporation, 1996. The above whole teaching is hereby incorporated into the present description by reference.
Although the biodegradable plastics are generally full of promise to solve the plastic disposal problems, there are also some difficulties. A biodegradation rate may be slower than the expected rate due to kinds and ratios of biodegradable plastic contents and also due to differences of the environment where the biodegradable plastics are disposed. In addition, another problem is that when a thickness of molded articles including biodegradable plastics increases, the biodegradability thereof reduces. Furthermore, the life of the molded articles including the biodegradable plastics may be shorten compared with the desired life due to insect pests. Further serious problems are that functions thereof are limited to optimally narrow objectives, or a large part of the macromolecules thereof are specially prepared so as to act certain parts during a manufacturing step. Partially degradable plastics including non-biodegradable plastics have not satisfactory quality. Therefore, improvement in biodegradability of all plastics with maintaining benefic characteristics of each biodegradable plastic is remarkably useful.
A method for achieving this object is using additives which make plastics to be easily degraded in the environment instead of fillers which are usually used now. At present, the additives to plastics are employed in order to give favorable characteristics to the plastics. For example, additives are used for giving characteristics such as strength, hardness, flexibility, and color.
The review concerning characteristics, application, and toxicity of the additives to plastics in detail is shown in “Chemical Additives for the Plastics Industry”, published by Radian Corporation and Noyes Data Corporation, N.J., U.S.A., 1987. The above whole teaching is hereby incorporated into the present description by reference.
One candidate which improves the degradability in the environment of the additives to the plastics is biomaterials such as plant fibers and wood powders. Since the plant fibers alone and wood powders include lignin (phenolic polymer) and have repellent nature to insects, these utilization reduces biodegradability.
In contrast, the inventors of the present invention have found that when the dry powders of the fibers included in coconut mesocarp are mixed with biodegradable plastics, the biodegradability thereof can be increased (JP-A-9-263700).
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a biodegradable plastic molded article having further superior biodegradability to the conventional art.
Another object of the present invention is to accelerate the biodegradability of the conventional biodegradable plastics preferably without deteriorating the processing characteristics such as good molding, extrusion, blow molding, foam molding, inflation molding and other molding methods.
Still another object of the present invention is to further improve the biodegradability of the conventional biodegradable plastics, and simultaneously to allow controlling a biodegradation rate of the biodegradable plastic molded articles.
To address the above-described problems, the inventors of the present invention performed careful examinations. As a result, the inventors of the present invention have found that when dry powders of water-swelling fibers and fertilizer powders are mixed with biodegradable plastics, the biodegradability thereof can be accelerated, so that the present invention has been completed
That is, an aspect of the present invention is a biodegradable plastic article molded of a mixture including the following components:
(A) biodegradable plastics at 98 to 59% by weight,
(B) a dry powder of a water-swelling fiber at 1 to 40% by weight, and
(C) fertilizer powder at 1 to 40% by weight
(wherein the sum of (B) and (C) is from 2 to 41% by weight).
In one embodiment, the present invention includes a biodegradable plastic molded article, wherein the dry powders of the water-swelling fibers include dry powders of coconut mesocarp fiber residues.
In another embodiment, the present invention includes a biodegradable plastic molded article, wherein the dry powders of the coconut mesocarp fibers residues are obtained by drying the fiber residues to a water content of about 10% by weight in which the residues are derived from a fiber components of the coconut mesocarp and contaminants including salts and tannin are essentially removed, by compressing into powders having a particle diameter ranging from 1 to 80 micron, and by drying to a water content of less than 3% by weight.
In still another embodiment, the present invention includes a biodegradable plastic molded article, wherein the biodegradable plastic is selected form the group consisting of aliphatic polyesters, macromolecular polysaccharides, and microbial polyesters.
In still another embodiment, the present invention includes a biodegradable plastic molded article, wherein the fertilizer is selected form the group consisting of nitrogenous fertilizers, phosphate fertilizers, potassium fertilizers, and fertilizers including diatomaceous.
Another aspect of the present invention is a biodegradable plastic article molded of a mixture including the following components:
(A) biodegradable plastics at 97 to 58% by weight,
(B) dry powders of water-swelling fibers at 1 to 40% by weight,
(C) fertilizer powders at 1 to 40% by weight, and
(D) a component selected form the group consisting of surfactants, stains, and agricultural chemicals at 1 to 10% by weight (wherein the sum of (B), (C), and (D) is from 3 to 42% by weight).
The present invention will be described in detail below.
The biodegradable plastic molded articles in accordance with the present invention show accelerated biodegradability by mixing dry powders of water-swelling fibers and fertilizer powders with biodegradable plastics. In addition, the adjustment of the mixed composition can control a degradation
Keiichi Sugimoto
Kilpatrick & Stockton LLP
LandOfFree
Biodegradable plastic molded article does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Biodegradable plastic molded article, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Biodegradable plastic molded article will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2967053