High temperature viscosity stable thickener

Details High temperature viscosity stable thickener High temperature viscosity stable thickener

1998-08-13

2004-07-13

Egwim, Kelechi C. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C524S827000, C524S832000, C524S833000, C526S307500, C526S307600, C526S318410, C526S318440, C526S320000, C526S329600, C526S333000

Reexamination Certificate

active

06762269

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a hydrophobe-containing alkali soluble or swellable copolymer thickener prepared from an ethylenically unsaturated copolymerizable surfactant monomer having a cloud point of 65° C. to 95° C. Aqueous compositions utilizing the copolymer exhibit constant or increased viscosity at temperatures approaching 120° C.
BACKGROUND OF THE INVENTION
Alkali soluble polymeric thickeners are described in U.S. Pat. No. 4,384,096, U.S. Re. Pat. No. 33,156, and U.S. Pat. Nos. 4,616,074, 4,384,096 describes alkali soluble polymeric thickeners which are aqueous emulsion copolymers of a &agr;,&bgr;-ethylenically unsaturated carboxylic acid monomer, a nonionic &agr;,&bgr;-ethylenically unsaturated comonomer, and a copolymerizable nonionic vinyl surfactant esters. U.S. Re. Pat. No. 33,156 describes alkali soluble polymeric thickeners which are aqueous emulsion copolymers of a &agr;,&bgr;-ethylenically unsaturated carboxylic acid monomer, a nonionic &agr;,&bgr;-ethylenically unsaturated monomer, and a nonionic urethane monomer. U.S. Pat. No. 4,616,074 describes alkali soluble polymeric thickeners which are aqueous emulsion copolymers of an addition copolymerizable substituted methylene succinic acid ester surfactant monomer, an &agr;,&bgr;-ethylenically unsaturated carboxylic acid monomer, and a nonionic &agr;,&bgr;-ethylenically unsaturated monomer.
The disadvantage of the above described alkali soluble polymeric thickeners is that at temperatures as low as 25° C., the viscosity of the thickeners begins to decrease and continues to decrease at an increasing rate as the temperature is further increased. Such decreasing viscosity properties exhibited by the thickeners at elevated temperatures severely limits the choice of applications for the alkali soluble thickeners. Therefore, it would be advantageous to develop a thickener wherein the viscosity of the thickener does not decrease at elevated temperatures.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide an alkali soluble or swellable thickened aqueous composition.
It is another object of the invention to provide a thickened aqueous composition in which the viscosity of the composition does not decrease at elevated temperatures.
It is also an object of the invention to provide a thickened aqueous composition in which the viscosity of the composition is constant or increases while being exposed to elevated temperatures.
With regard to the foregoing and other objects, the present invention provides a hydrophobe-containing alkali soluble or swellable copolymer thickener which provides aqueous compositions with constant or increased viscosity at temperatures approaching 120° C., wherein said copolymer comprises an emulsion polymerization product of
(A) from about 0.1 to about 25 weight percent, based on the total weight of the copolymer, of an ethylenically unsaturated copolymerizable surfactant monomer having a cloud point of from about 65° C. to about 95° C., wherein the surfactant monomer has the formula
M(EO)
x
(PO)
y
(BO)
z
OR
1
wherein M is a residue selected from the group consisting of an ethylenically unsaturated carboxylic acid, ethylenically unsaturated dicarboxylic acid, and a copolymerizable isocyanate; EO is an ethylene oxide unit; PO is a propylene oxide unit; BO is a butylene oxide unit; x is from 10 to 45; y is from 0 to 35; z is from 0 to 35; provided that x+y+z is from 20 to 45; and R
1
is selected from the group consisting of alkyl, alkylene, cycloalkyl, cycloalkylene, and arylalkyl group wherein the alkyl group has 1 to 30 carbon atoms;
(B) from about 20 to about 70 weight percent, based on the total weight of the copolymer, of an &agr;,&bgr;-ethylenically unsaturated monocarboxylic acid monomer having the formula
wherein R
2
is selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, and —CH
2
COOR
3
; and R
3
is hydrogen or an alkyl group having 1 to 4 carbon atoms; and
(C) from about 10 to about 70 weight percent, based on the total weight of the copolymer, of a nonionic &agr;,&bgr;-ethylenically unsaturated monomer having the formula
CH
2
═CR
4
R
5
wherein R
4
is selected from the group consisting of hydrogen, methyl and Cl; and R
5
is selected from the group consisting of CN, Cl, —COOR
6
, —C
6
H
4
R
7
, —CH═CH
2
,
wherein R
6
is selected from the group consisting of hydrogen, Cl, Br, and an alkyl group having 1 to 4 carbon atoms; R
7
is an alkyl group having 1 to 12 carbon atoms or a hydroxyalkyl group having 2 to 8 carbon atoms; and R
8
is an alkyl group having 1 to 8 carbon atoms.
According to another aspect the invention provides a method for making a thickened aqueous composition wherein said method comprises: (I) preparing a copolymer as described above; (II) combining the copolymer prepared in Step (I) with a composition comprising water at a pH of from about 2 to about 5 to form an aqueous copolymer dispersion; and (III) at least partially neutralizing said aqueous copolymer dispersion prepared in Step (II) to a pH of at least about 5.5 to form a hydrophobe-containing alkali soluble or swellable thickened aqueous composition which exhibits constant or increased viscosity at temperatures approaching 120° C.
The hydrophobe-containing alkali soluble or swellable copolymer thickeners of the invention thicken aqueous compositions and maintain or increase the viscosity of the thickened aqueous composition at temperatures approaching 120° C. Thus, the copolymer thickeners of the invention exhibit enhanced thickening efficiency in comparison with prior art copolymers. In addition, a reduced quantity of copolymer thickener is required to achieve a fixed level of thickening in comparison with the amount of prior art thickeners.


REFERENCES:
patent: 4268641 (1981-05-01), Koenig et al.
patent: 4351754 (1982-09-01), Dupré
patent: 4384096 (1983-05-01), Sonnabend
patent: 4421902 (1983-12-01), Chang et al.
patent: 4616074 (1986-10-01), Ruffner
patent: RE33156 (1990-01-01), Shay et al.
patent: 5294692 (1994-03-01), Barron et al.
patent: 5461100 (1995-10-01), Jenkins et al.
patent: 5661206 (1997-08-01), Tanaka et al.
patent: WO 97/00275 (1997-01-01), None

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