Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-11-15
2003-07-29
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S112000, C525S133000, C525S162000, C525S187000, C523S122000, C524S377000
Reexamination Certificate
active
06599979
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polymer composition containing carboxyl group having good solubility, thickening property and flow characteristics and suited for use as a thickener for various aqueous solutions.
BACKGROUND ART
Crosslinked polymer containing carboxyl group have so far been used as thickeners for various aqueous solutions. Such crosslinked polymers containing carboxyl group include, among others, copolymers of an &agr;,&bgr;-unsaturated carboxylic acid, such as acrylic acid, and a polyallyl ether (U.S. Pat. No. 2,923,692), copolymers of an &agr;,&bgr;-unsaturated carboxylic acid and hexaallyltrimethylene trisulfone (U.S. Pat. No. 2,958,679), copolymers of an &agr;,&bgr;-unsaturated carboxylic acid and triallyl phosphate (U.S. Pat. No. 3,426,004) and copolymers of an &agr;,&bgr;-unsaturated carboxylic acid and glycidyl methacrylate or the like (Japanese Kokai Publication Sho-58-84819).
These crosslinked polymers containing carboxyl group are once dissolved in water and then neutralized with an alkali, and the neutralized viscous liquids are used as thickeners, as suspension stabilizers for emulsions or suspensions, and for other purposes. Therefore, it is necessary to first prepare uniform aqueous solutions. It is thus of primary importance to prevent a formation of undissolved powder lumps on the occasion of dissolution in water. Once an undissolved powder lump is formed, a gel-like layer is formed on the lump surface and this decreases the rate of diffusion of water into the lump inside and makes it difficult to obtain a uniform aqueous solution.
Moreover, the higher the viscosity of the neutralized viscous liquid is, the wider the field of application as a thickener becomes and the lesser the amount required is. Further, for the flowing characteristics such as yield value, the higher the yield value is, the wider the field of application as a suspension stabilizer for emulsions and suspensions, hence the commercial value becomes higher.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a polymer composition containing carboxyl group which is excellent in water solubility, in thickening effect and in flow characteristics of the neutralized viscous liquid obtained after neutralization of the aqueous solution.
The gist of the present invention lies in that the polymer composition containing carboxyl group comprises (A) a crosslinked polymer prepared from (a) an &agr;,&bgr;-unsaturated carboxylic acid and (b) a compound having at least two ethylenically unsaturated groups, and (B) at least one of a polymer comprising vinylpyrrolidone as an essential constituent thereof, and polyethylene oxide.
DETAILED DESCRIPTION OF THE INVENTION
In the following, the present invention is described in further detail.
The &agr;,&bgr;-unsaturated carboxylic acid (a) to be used in the practice of the present invention is not limited to any particular species but includes, among others, acrylic acid, methacrylic acid, crotanic acid, maleic acid, itaconic acid, fumaric acid and other olefinic unsaturated carboxylic acids.
These may be used either singly or in combination as a mixture of two or more. Among them, acrylic acid is most preferred since it is readily available at low cost and can give polymers having good performance.
The compound (b) having at least two ethylenically unsaturated groups, which is to be used in the practice of the present invention, is not limited to any particular species provided that it is soluble in the inert solvent to be described later herein. Thus, it includes, among others, acrylate esters with two or more acryloyl moieties as derived from polyols such as ethylene glycol, propylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, glycerol, polyglycerol, trimethylolpropane, pentaerythritol, saccharose, sorbitol, etc.; methacrylate esters with two or more methacryloyl moieties as derived from such polyols; allyl ethers with two or more allyl moieties as derived from such polyols; diallyl phthalate, triallyl phosphate, allyl methacrylate, tetraallyloxyethane, triallyl cyanurate, divinyl adipate, vinyl crotonate, 1,5-hexadiene, divinylbenzene, and the like. Among these, pentaerythritol tetraallyl ether, tetraallyloxyethan, triallyl phosphate and polyallylsaccharose are preferred since they can give polymers with good performance.
The above-mentioned compound (b) having at least two ethylenically unsaturated groups is used preferably at an addition level of 0.05 to 10% by weight based on the crosslinked polymer (A). At addition levels below 0.05% by weight, the addition produces no or little effect while at addition levels exceeding 10% by weight, the polymer reaches an advanced three-dimensional state, resulting in formation of insoluble gels. A more preferred addition level lies within the range of 0.1 to 3% by weight. An optimal addition level may vary depending on various factors, however.
The polymer comprising vinylpyrrolidone as an essential constituent thereof, which is to be used in the practice of the present invention, is not limited to any particular species but includes polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer, vinylpyrrolidone-stearyl (meth)acrylate copolymer, vinylpyrrolidone-dimethylaminoethyl (meth)acrylate copolymer, diethyl sulfate salt of vinylpyrrolidone-dimethylaminoethyl methacrylate copolymer, vinylpyrrolidone-hexadecene copolymer, vinylpyrrolidone-eicosene copolymer, vinylpyrrolidone-styrene copolymer, vinylpyrrolidone-vinyl alcohol copolymer, vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl (meth)acrylate terpolymer, vinylpyrrolidone-methacrylamidopropyltrimethylammo nium chloride copolymer, and the like. Among them, polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer, vinylpyrrolidone-hexadecene copolymer and vinylpyrrolidone-eicosene copolymer are preferred since these can give polymer compositions having good performance characteristics.
The content of (B), namely at least one member selected from among polymers comprising vinylpyrrolidone as an essential constituent thereof and polyethylene oxide, may vary depending on the species and molecular weight thereof and other conditions but, generally, it is 0.01 to 60 parts by weight per 100 parts by weight of crosslinked polymer (A). When the content is below 0.01 part, no or little effect can result from the addition. When it exceeds 60 parts by weight, the thickening effect of the resulting polymer composition containing carboxyl group decreases. A more preferred content range is 0.1 to 10 parts by weight.
The polymer composition containing carboxyl group of the present invention can be produced, for example, in the following manner.
A reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube and condenser is charged with an &agr;,&bgr;-unsaturated carboxylic acid (a), a compound (b) having at least two ethylenically unsaturated groups, radical polymerization catalyst, inert solvent, and the component (B), namely at least one of a polymer comprising vinylpyrrolidone as an essential constituent thereof and polyethylene oxide.
On that occasion, the total amount to be charged of the &agr;,&bgr;-unsaturated carboxylic acid (a) and the compound (b) having at least two ethylenically unsaturated groups is preferably 1 to 30% by weight relative to the total charge. When said amount exceeds 30% by weight, polymer deposition becomes significant and the reaction mixture becomes difficult to uniformly agitate with the progress of the polymerization reaction. A more preferred range is 5 to 25% by weight.
After attaining uniform mixing with stirring, gaseous nitrogen is blown into the solution to thereby purge off oxygen in the upper space of the reaction vessel and oxygen dissolved in the starting materials and solvent. The polymerization reaction is initiated by heating to 20° C. to 120° C. , preferably to 30° C. to 90° C. , on a water bath or the like. Generally, the polymerization reaction will be complete in 2 to 10 hours.
After completion of the polymeri
Fujikake Masato
Hamamoto Shigeki
Kawakita Tomoki
Kobayashi Shinji
Tabata Mitsutaka
Connolly Bove & Lodge & Hutz LLP
Sumitomo Seika Chemicals Co. Ltd.
Zalukaeva Tatyana
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