Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using disinfecting or sterilizing substance
Reexamination Certificate
2001-06-01
2003-12-30
Thornton, Krisanne (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using disinfecting or sterilizing substance
C422S001000, C422S040000, C424S404000, C424S413000, C514S057000, C514S163000, C514S506000, C514S781000
Reexamination Certificate
active
06669903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a bactericidal or bacteriostatic method using cellulose acetate.
2. Related Background Art
Conventionally, inorganic antibacterial agents such as a silver compound or organic antibacterial agents containing an organic compound have been utilized as antibacterial agents used for sterilization or bacteriostasis. In addition, photocatalysts such as titanium oxide, etc. produce active oxygen by photoirradiation. This active oxygen provides an antibacterial action. Hence, titanium oxide or the like also may be used as antibacterial agents.
However, there has been a problem that conventional antibacterial agents have short lives. Accordingly, even when, for instance, resin products using such conventional antibacterial agents exhibit an antibacterial action at the beginning of use, various bacteria propagate or molds (fungi) grow after a certain period of time. Furthermore, conventional antibacterial agents include those that cannot provide effective sterilization or bacteriostatic actions against pathogenic bacteria including, for example, serious alimentary intoxication bacteria such as enteropathogenic
Escherichia coli
O-157 and methicillin resistant
Staphylococcus aureus
(MRSA). Even if the conventional antibacterial agents are effective for such bacteria, some of them may have harmful effects on human bodies. In order to provide a resin product or the like with an antibacterial property by using a conventional antibacterial agent, it has been necessary to add and knead the conventional antibacterial agent as an additive. When a sufficient antibacterial property is intended to be provided, it has been necessary to add and knead a large amount of antibacterial agent. This causes a disadvantage in cost and also affects the characteristics of the resin product. On the other hand, the photocatalysts do not allow an antibacterial action to be expressed without the help of light. Therefore, the use of such photocatalysts may be limited in some cases. Moreover, many of the conventional antibacterial agents are expensive and thus their use may be limited in view of their cost.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind, it is an object of the present invention to provide a safe, simple, and inexpensive method enabling excellent long-term sterilization or bacteriostasis.
In order to achieve the above-mentioned object, the present invention is directed to a method in which cellulose acetate is used for sterilization or bacteriostasis.
The present inventor examined the antibacterial ability of natural organic substances to obtain an antibacterial substance that can solve all the aforementioned problems. As a result, he found out that cellulose acetate had excellent bactericidal and bacteriostatic ability. A particularly remarkable point is that the cellulose acetate exhibits an excellent bactericidal property even against the enteropathogenic
Escherichia coli
O-157, MRSA, and Trichophyton. The bactericidal or bacteriostatic property of the cellulose acetate remains as long as the cellulose acetate is present and accordingly, lasts for a long period. In addition, since the cellulose acetate is one type of resin, the cellulose acetate itself can be used for a resin product. Even when the cellulose acetate is mixed with other resins, there is a lower possibility that the cellulose acetate may affect the characteristics of the other resins, as compared to the case of conventional antibacterial agents. Moreover, the cellulose acetate is less expensive than the conventional antibacterial agents, is derived from a natural product, and has no safety problem, which has been proved by actual use over a long period.
It is not clear why the cellulose acetate exhibits the bactericidal or bacteriostatic property. However, the present inventor assumes that acetyl groups in the cellulose acetate cause the bactericidal property or the like to be expressed. In the following description, the term “antibacterial” includes the meanings of both “sterilization” and “bacteriostasis”.
Preferably, the cellulose acetate used in the method of the present invention includes acetyl groups in a ratio of 1 to 3 per glucose residue, particularly preferably, in a ratio of 2.5 per glucose residue on average.
In the method of the present invention, preferably, the cellulose acetate is used together with boric acid. According to the knowledge that the present inventor has acquired, the cellulose acetate has an excellent antibacterial property against, for example, alimentary intoxication bacteria or pathogenic bacteria but is decomposed by
Bacillus subtilis
. This denotes that the cellulose acetate has a biodegradation property. This can be an advantage but also may be a disadvantage depending on the intended use. Hence, when the antibacterial action of the cellulose acetate is intended to be exhibited for a longer period of time, it is preferable that the cellulose acetate and boric acid (an antibacterial agent against the
Bacillus subtilis
) be used together as described above. The ratio of boric acid to be added to the cellulose acetate is, for example, 100 ppm to 1000 ppm, preferably 200 ppm to 600 ppm, and further preferably 200 ppm to 300 ppm.
DETAILED DESCRIPTION OF THE INVENTION
In the method of the present invention, the form of cellulose acetate to be used is not particularly limited. For example, the cellulose acetate may be used as an additive agent (an antibacterial agent) or may be processed into a plastic molded article, a coating material, a spray agent, or a textile product.
When used as an antibacterial agent, the cellulose acetate generally is present in a granular form. The grain size of such cellulose acetate is, for example, 0.001 to 5 mm, preferably, 0.001 to 2 mm, and further preferably 0.001 to 0.5 mm. The antibacterial agent may contain components other than the cellulose acetate, for example, a plasticizer such as phthalic acid. The granular antibacterial agent can be produced by, for example, a method including mixing a plasticizer (such as phthalic acid) with cellulose acetate (fine powder), kneading and extruding the mixture in a strand form with a twin screw extruder, and cutting it with a cutter. The mass ratio between the cellulose acetate and the plasticizer is as follows: for example, cellulose acetate:plasticizer=80:20.
Examples of items for which the cellulose acetate antibacterial agent can be used include resin products, coating materials, and textile products. When these products are produced, the antibacterial agent may be mixed with their main raw materials. Products thus obtained are provided with an excellent antibacterial property.
Next, in the method of the present invention, the cellulose acetate can be processed to form a plastic molded article. In this case, preferably, another resin is blended with the cellulose acetate depending on the intended use. Examples of another resin to be blended include thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, fluororesin, acrylic resin, methacrylic resin, polyvinyl acetate, polyamide, acetal resin, polycarbonate, polyphenylene oxide, polyester (polyethylene terephthalate, polybutylene terephthalate, aromatic polyester, polyallylate, etc.), polysulfone-based resin, and polyimide. Besides such thermoplastic resins, a thermosetting resin may be blended. Examples of such a thermosetting resin include phenolic resin, melamine resin, alkyd resin, unsaturated polyester resin, silicone resin, epoxy resin, urea resin, and urethane resin. The plastic molded article can be in a form of, for example, sheet, film, or rod, but is not particularly limited thereto. The ratio of the cellulose acetate in the plastic molded article is, for example, 1 to 100 mass %, preferably 10 to 100 mass %, and further preferably 30 to 100 mass %. For example, the methods of the examples described later can be used for processing the cellulose acetate into a plastic molded art
Hayashi Michio
Merchant & Gould P.C.
Thornton Krisanne
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