Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Reexamination Certificate
2000-04-06
2002-02-12
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
Reexamination Certificate
active
06346600
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to: a vinylpyrrolidone polymer which is excellent in the storage stability; a composition containing the vinylpyrrolidone polymer; a stabilization process for the vinylpyrrolidone polymer; and a preservation process for the vinylpyrrolidone polymer.
B. Background Art
A vinylpyrrolidone polymer, such as poly(vinylpyrrolidone) or a vinylpyrrolidone copolymer, is widely used in various fields such as medicines, cosmetics, pressure sensitive adhesives or adhesives, paints, dispersants, inks, and electronic parts, because the vinylpyrrolidone polymer has merits or advantages of biocompatibility, safety, hydrophilicity, and so on.
However, while providing the vinylpyrrolidone polymer to the above various uses, the present applicant found that the vinylpyrrolidone polymer had problems in respect to the stability of storability and so on. For example, whether the vinylpyrrolidone polymer is a powder or solution, there were cases where the vinylpyrrolidone polymer or a solution thereof got colored or underwent the reduction of the molecular weight or viscosity when stored for a long time or at high temperature.
SUMMARY OF THE INVENTION
A. Object of the Invention
An object of the present invention is to provide: a vinylpyrrolidone polymer which has extremely good storage stability and thermal stability in that even if the vinylpyrrolidone polymer is stored for a long time, coloring or other changes of physical properties occur little, and the thermal stability is also excellent, and the storage in a solution state is also possible; a composition containing the vinylpyrrolidone polymer; and a stabilization process for the vinylpyrrolidone polymer.
Another object of the present invention is to provide a preservation process for a vinylpyrrolidone polymer by which: even when the vinylpyrrolidone polymer is preserved for a long time or at high temperature, the physical properties such as molecular weight (K value) of the vinylpyrrolidone polymer can be prevented from changing, therefore the vinylpyrrolidone polymer can stably be preserved.
B. Disclosure of the Invention
The present inventor diligently studied to solve the above problems. As a result, the inventor found that the above problems could be solved if the vinylpyrrolidone polymer was mixed with a certain amount of antioxidant, and further that a process, comprising the step of examining how much a K value, as defined by Fikentscher's equation, reduced when heating the vinylpyrrolidone polymer under prescribed conditions, was good as a process for exactly judging the storage stability of the vinylpyrrolidone polymer. The inventor also found that the above problems could be solved if the oxygen concentration in a gas phase that contacts with the vinylpyrrolidone polymer was kept to a certain amount or less when preserving. The present invention has been completed on the basis of these findings.
Therefore, a vinylpyrrolidone polymer, according to the present invention, contains at least one antioxidant in a ratio of 0.00001~30 weight %, preferably 0.001~30 weight %, to the vinylpyrrolidone polymer. Another vinylpyrrolidone polymer, according to the present invention, is adjusted such that the reduction ratio of the K value defined by Fikentscher's equation will be within 5% when the vinylpyrrolidone polymer is subjected to a forcible test in which the vinylpyrrolidone polymer is kept heated at 120° C. under normal pressure in air for 2 hours. Yet another vinylpyrrolidone polymer, according to the present invention, is adjusted such that the reduction ratio of the K value defined by Fikentscher's equation will be within 5% when the vinylpyrrolidone polymer is subjected to a promotion test in which the vinylpyrrolidone polymer is kept heated at 50° C. in a solution state for 14 days.
A composition for various uses, according to the present invention, comprises a vinylpyrrolidone polymer as a resin component, and further comprises at least one antioxidant in a ratio of 0.00001~30 weight %, preferably 0.001~30 weight %, to the vinylpyrrolidone polymer.
A stabilization process for a vinylpyrrolidone polymer, according to the present invention, comprises the step of mixing the vinylpyrrolidone polymer with at least one antioxidant in a ratio of 0.00001~30 weight %, preferably 0.001~30 weight %, to the vinylpyrrolidone polymer.
A preservation process for a vinylpyrrolidone polymer, according to the present invention, comprises the step of suppressing the oxygen concentration to not higher than 50,000 ppm in a gas phase that contacts with the vinylpyrrolidone polymer.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a detailed description is given about a mode for carrying out the present invention.
The vinylpyrrolidone polymer in the present invention is, specifically, poly(vinylpyrrolidone) and/or a vinylpyrrolidone copolymer.
The poly(vinylpyrrolidone) is a compound of general formula (3) below:
(wherein n is an integer) and is obtained by polymerizing vinylpyrrolidone by any method as mentioned below.
The vinylpyrrolidone copolymer is a copolymer of which the constituents include vinylpyrrolidone and a comonomer copolymerizable therewith. The comonomer to be copolymerized with vinylpyrrolidone is not especially limited, but specific examples thereof include: 1) (meth)acrylate esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, and hydroxyethyl (meth)acrylate; 2) (meth)acrylamide and derivatives therefrom such as N-monomethyl(meth)acrylamide, N-monoethyl(meth)acrylamide, and N,N-dimethyl(meth)acrylamide; 3) basic unsaturated monomers such as dimethylaminoethyl (meth)acrylate, dimethylaminoethyl(meth)acrylamide, vinylpyridine, and vinylimidazole and their salts or quaternized products; 4) vinylamides such as vinylformamide, vinylacetamide, and vinyloxazolidone; 5) carboxyl-group-containing unsaturated monomers such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid; 6) unsaturated anhydrides such as maleic anhydride and itaconic anhydride; 7) vinyl esters such as vinyl acetate and vinyl propionate; 8) vinylethylene carbonate and derivatives therefrom; 9) styrene and derivatives therefrom; 10) 2-sulfoethyl (meth)acrylate and derivatives therefrom; 11) vinylsulfonic acid and derivatives therefrom; 12) vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; and 13) olefins such as ethylene, propylene, octene, and butadiene. Among these groups of comonomers, particularly, groups 1)~8) are favorable, for example, in respect to the copolymerizability with vinylpyrrolidone. As to the above comonomers, only one kind may be copolymerized with vinylpyrrolidone, or any mixture of two or more kinds of comonomers may be copolymerized with vinylpyrrolidone.
The ratio of vinylpyrrolidone to the entire monomer components of the vinylpyrrolidone copolymer is not especially limited, but is preferably not lower than 0.1 mol %, more preferably not lower than 1.0 mol %, still more preferably not lower than 5.0 mol %, most preferably not lower than 20.0 mol %. In the case where the ratio of vinylpyrrolidone in the copolymer is lower than 0.1 mol %, there are disadvantages in that various properties deriving from vinylpyrrolidone cannot be exhibited and the deterioration of the polymer to be solved by the present invention is seen little.
The polymerization reaction to give the vinylpyrrolidone polymer can be carried out by conventional polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and precipitation polymerization. The reaction temperature in the polymerization reaction may fitly be set according to conditions such as reactants, but is preferably in the range of 0~250° C., more preferably 20~150° C., most preferably 40~100° C.
The polymerization reaction
Kuriyama Toshiaki
Naka Akio
Nakata Yoshitomo
Nishibayashi Hideyuki
Tomihisa Daijo
Boykin Terressa M.
Nippon Shokubai Co. , Ltd.
Roylance Abrams Berdo & Goodman L.L.P.
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