Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
1999-03-18
2001-03-13
Travers, Russell (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S078080, C424S405000, C514S315000, C514S316000
Reexamination Certificate
active
06200583
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
This invention relates to antimicrobial agents, especially to antimicrobial agents capable of imparting excellent weatherability to resins, synthetic fibers or the like without impairing the safety and transparency of these materials. This invention is also concerned with resin compositions making use of the above antimicrobial agents and further with articles making use of these resin compositions.
b) Description of the Related Art
Traditionally, antimicrobial agents have been classified roughly into an inorganic type and an organic type. A problem associated with inorganic antimicrobial agents is that, when incorporated as additives in resins, synthetic resins, paints or the like, resulting products are deteriorated in physical properties such as transparency and mechanical strength although these products are good in heat resistance and weatherability. With respect to the safety of inorganic antimicrobial agents, on the other hand, their effects on the ecosystem due to accumulation of metals such as silver as a result of future mass consumption are of concern because these antimicrobial agents contain metal ions such as silver ions.
A problem associated with organic antimicrobial agents, on the other hand, is that when incorporated as additives in resins, synthetic fibers, paints or the like, resulting products are accompanied by drawbacks in heat resistance and weatherability although these products are good in mechanical strength. Depending on the kinds of organic antimicrobial agents employed, a problem with respect to the transparency of resulting products may also arise.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the above-described problems and hence to provide an antimicrobial agent which, when incorporated as additives in resins, synthetic fibers or the like, can impart excellent weatherability and deterioration resistance to resulting products without impairing the transparency and safety of these materials.
As a result of extensive research, the present inventors have found that a 2,2,6,6-tetramethyl-4-piperidine derivative, when added to resins, synthetic fibers or the like, can impart stable antimicrobial activity and excellent weatherability and deterioration resistance to these materials without impairing their transparency and safety, leading to the completion of the present invention.
To achieve the above object, the present invention provides an antimicrobial agent comprising a 2,2,6,6-tetramethyl-4-piperidine derivative, an antimicrobial resin composition comprising the antimicrobial agent, and an antimicrobial article comprising the antimicrobial resin composition.
The antimicrobial agent according to the present invention can impart not only excellent antimicrobial activity but also superb heat resistance, weatherability and deterioration resistance to resins, synthetic fibers or the like without imparting the safety and transparency of these materials. Further, the resin composition making use of the antimicrobial agent and the article made of the resin composition have the above-described outstanding properties.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
The present invention will next be described in further detail on the basis of preferred embodiments. 2,2,6,6-Tetramethyl-4-piperidine derivatives useful in the practice of the present invention are compounds having the following structure in their molecules.
wherein R represents a hydrogen atom or an alkyl group.
As 2,2,6,6-tetramethyl-4-piperidine derivatives for use in the present invention, known compounds can be employed. Particularly preferred are the following compounds (a)-(e):
(a) Bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate
(b) Poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazin-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}]
(c) A mixed ester of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol) and 3,9-bis(2- hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]-udecane
(d) Tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate
(e) Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate
Among the above compounds, the compounds (a) and (b) are especially good in safety because they are described in the Positive List of Japan Hygienic Olefin and Styrene Plastics Association (JHOSPA) and their use in food containers and packages is permitted. These compounds can be used either singly or in combination.
The 2,2,6,6-tetramethyl-4-piperidine derivatives useful in the practice of the present invention have melting points or softening points in a range of from 80 to 135° C. and have excellent dispersibility in resins, so that they can provide antimicrobial resin compositions having high transparency.
The 2,2,6,6-tetramethyl-4-piperidine derivatives useful in the practice of the present invention are known to impart weatherability and deterioration resistance especially to resins, and can hence provide superior antimicrobial resin compositions to conventional organic antimicrobial agents.
The antimicrobial activity of each antimicrobial agent according to the present invention appears to be developed through a mechanism to be described next. Namely, the 2,2,6,6-tetramethyl-4-piperidine structure is believed to form a quaternary ammonium salt, which is considered to induce injuries of cell membranes and walls of microorganisms and denaturation and/or respiratory inhibition of zymoproteins, thereby presumably exhibiting antimicrobial activity.
No particular limitation is imposed on the resin to be used in the antimicrobial resin composition according to the present invention. Illustrative usable resins can include polyethylene resins, polypropylene resins, polyester resins, polystyrene resins, polyvinyl chloride resins, polyurethane resins, polyacrylic resins, polyamide resins, polyvinyl alcohol resins, and cellulose resins.
No particular limitation is imposed on the amount of the 2,2,6,6-tetramethyl-4-piperidine derivative to be used in the antimicrobial resin composition according to the present invention. Its preferred amount may however range from 0.05 to 5 parts by weight per 100 parts by weight of the resin. An amount of the 2,2,6,6-tetramethyl-4-piperidine derivative smaller than 0.05 part by weight leads to low antimicrobial effect, so that in the case of bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, antimicrobial effect can hardly be observed against Gram-negative bacteria. On the other hand, an amount of the 2,2,6,6-tetramethyl-4-piperidine derivative greater than 5 parts by weight involves a potential problem that physical properties of the resulting resin composition may be adversely affected.
Pigments, resin additives, other antimicrobial agents and/or the like can be added in the antimicrobial resin composition according to the present invention to such extents as not impairing the advantageous effects of the present invention. No particular limitation is imposed on the article having antimicrobial activity according to the present invention insofar as it is made of the antimicrobial resin composition according to the present invention. As illustrative examples, however, the following articles may be mentioned.
(1) Molded or otherwise formed, antimicrobial articles:
Articles obtained by molding or otherwise forming antimicrobial resin compositions of the invention by injection molding, extrusion, blow molding or the like. More specific examples can include food containers, waste or rubbish receptacles, stationery, housings of electric or electronic appliances, cosmetic containers, vehicle interior parts, kitchen utensils, bathroom utensils, and clothing storage containers.
(2) Antimicrobial fibers:
Articles obtained by forming the antimicrobial resin compositions of the present invention into fibers by spinning or the like, and those obtained by forming such fibers into woven fabrics or nonwoven fabrics. More
Hayashi Kozaburo
Hoshino Akira
Sibata Masayuki
Dainichiseika Color & Chemicals Mfg. Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Travers Russell
Wang Shengiun
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