Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-10-25
2001-08-14
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S035000, C524S039000, C524S047000, C536S123000
Reexamination Certificate
active
06274652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a polymeric composite material containing a biodegradable polymeric substance to make it biodegradable in soil and also to a method of manufacturing such a composite material. More specifically, it relates to a composite material of bacterial cellulose and a biodegradable polymeric substance and also to a method of manufacturing such a composite material.
2. Description of the Prior Art
Conventionally, synthetic resin is widely used as material for manufacturing containers for containing various objects and cabinets for housing audio and video apparatus as well as other electronic apparatus.
When disposing used containers and electronic apparatus that are made of synthetic resin as waste, they are mostly incinerated at high temperature in an incineration furnace. When incinerated, synthetic resin decomposes to substances that contaminate air. Attempts have been made to reuse synthetic resin materials in order to bypass the problems that may arise when incinerating synthetic resin. However, the reuse of synthetic resin materials requires a large capital investment for building gigantic incineration facilities and is accompanied by the difficulty of recovering synthetic resin materials showing desired properties.
Particularly, tens of several percent of newly produced synthetic resin materials are currently not reused and simply disposed by way of incineration or by some other means of waste disposal. Synthetic resin materials that are disposed without being incinerated mostly remain in soil or in water to contaminate the environment.
Biodegradable polymeric materials that are decomposed to low molecular weight substances by microbes in soil or in water have been proposed as alternatives that can avoid incineration for waste disposal. In particular, such materials are advantageously used for containers, electronic apparatus and fishing lines.
Then, containers and electronic apparatus made of a biodegradable composite material can be buried for waste disposal in the ground because they are eventually decomposed. Therefore, they do not have to be incinerated at high temperatures for waste disposal.
A biodegradable polymeric material is used alone or with one or more than one inorganic substances added thereto to form a composite material. More specifically, a biodegradable polymeric material may be used by itself to produce containers and cabinets of electronic apparatus or may be used with one or more than one inorganic substances added thereto to form a composite material that shows improved physical properties and mechanical strength for the products made of it. When used alone, a biodegradable polymeric material normally does not show satisfactory physical properties and hence its scope of application is limited. Therefore, one or more than one inorganic substances are typically added to a biodegradable polymeric material in order to improve some of the physical properties of its products and enlarge the scope of application.
When one or more than one inorganic substances are added, a biodegradable polymeric material can contaminate the natural environment if buried in the ground because all or some of the inorganic substances remain undecomposed in the ground.
Meanwhile, cabinets of audio/video apparatus and other electronic apparatus are required to show excellent physical properties including a strong tensile strength. Therefore, it is normally highly difficult to prepare cabinets of audio/video apparatus and other electronic apparatus by using only a biodegradable polymeric material. Thus, a biodegradable polymeric material is normally used with one or more than one inorganic substances added thereto to prepare cabinets of electronic apparatus that show an enhanced degree of tensile strength.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a polymeric material that can be decomposed with ease when buried in soil and shows improved physical properties to ensure a remarkable mechanical strength when used to form containers and electronic apparatus. Another object of the invention is to provide a method of manufacturing such a polymeric material.
A polymeric composite material according to the invention contains bacterial cellulose including ribbon-shaped micro-fibrils and a biodegradable polymeric material.
Of a polymeric composite material according to the invention, the bacterial cellulose and the biodegradable polymeric material can be biologically decomposed by respective microbes living in soil and/or in water and the bacterial cellulose can improve various physical properties of the polymeric composite material including the tensile strength thereof.
According to the present invention, there is also provided a method of manufacturing a polymeric composite material comprising steps of causing predetermined microbes cultured in a liquid culture medium to produce bacterial cellulose, collecting and drying the produced bacterial cellulose into a powdery state and mixing the powdery bacterial cellulose and a biodegradable polymeric material to produce a composite material.
Since this manufacturing method employs powdery bacterial cellulose, the bacterial cellulose and the biodegradable polymeric material can be mixed well to produce a composite material without difficulty. In other words, the bacterial cellulose can be dispersed into the biodegradable polymeric material with ease.
Other objects and advantages of the present invention will become apparent from the following description on examples.
REFERENCES:
patent: 4742164 (1988-05-01), Iguchi et al.
patent: 61-281800 (1986-12-01), None
patent: 62-36467 (1987-02-01), None
patent: 8-269888 (1996-10-01), None
Tokura Kunihiko
Uryu Masaru
Nutter Nathan M.
Sonnenschein Nath & Rosenthal
Sony Corporation
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