Thickening System and Method
Paint formulations that exhibit improved performance characteristics due to the presence of a combination of a cellulose ether (carboxymethylcellulose and/or hydroxyethylcellulose) and a network building polymer (gellan gum, carrageenan, etc., as examples) as a thickening system therein are provided. Such a combination permits long-term shelf stability of the paint formulation while simultaneously according effective flow, leveling, and other important properties to the final paint formulation. The combination of the cellulose ether and a network building polymer allows for a lower viscosity cellulosic compound to impart the desired rheological behavior therein while also permitting the other desirable characteristics noted above. Such paint compositions also exhibit improved atomization for spray applications with such a thickening system.
1 .- 18 . (canceled)
19 . A thickening system comprising at least one cellulose ether and at least one network building polymer, wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 40:1, respectively.
20 . The thickening system of claim 19 wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 20:1.
21 . The thickening system of claim 19 wherein:
the at least one cellulose ether is selected from the group consisting of carboxymethyl cellulose (CMC), hydroxylethyl cellulose (HEC), ethyl hydroxylethyl cellulose (EHEC), methyl cellulose (MC), methyl hydroxylethyl cellulose (MHEC), hydroxypropylmethyl cellulose (HPMC) ethers, and any mixtures thereof; and
the at least one network building polymer is selected from the group consisting of gellan gum, carrageenan, pectin, alginate, agar, gelatin, and blends thereof.
22 . The thickening system of claim 19 wherein the at least one cellulose ether is CMC and the at least one network building polymer is gellan gum.
23 . The thickening system of claim 22 wherein the gellan gum is low acyl gellan gum.
24 . The thickening system of claim 22 wherein the gellan gum is high acyl gellan gum.
25 . The thickening system of claim 22 wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 20:1.
26 . The thickening system of claim 22 wherein the CMC has a molecular weight from about 30,000 to 1,000,000 Daltons.
27 . The thickening system of claim 22 wherein the CMC has a degree of substitution between 0.5 and 1.5.
28 . The thickening system of claim 22 wherein the gellan gum has a molecular weight from about 400,000 to 700,000 Daltons.
29 . A thickening system consisting essentially of at least one cellulose ether and at least one network building polymer, wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 40:1, respectively.
30 . The thickening system of claim 29 wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 20:1.
31 . The thickening system of claim 29 wherein:
the at least one cellulose ether is selected from the group consisting of carboxymethyl cellulose (CMC), hydroxylethyl cellulose (HEC), ethyl hydroxylethyl cellulose (EHEC), methyl cellulose (MC), methyl hydroxylethyl cellulose (MHEC), hydroxypropylmethyl cellulose (HPMC) ethers, and any mixtures thereof; and
the at least one network building polymer is selected from the group consisting of gellan gum, carrageenan, pectin, alginate, agar, gelatin, and blends thereof.
32 . The thickening system of claim 29 wherein the at least one cellulose ether is CMC and the at least one network building polymer is gellan gum.
33 . The thickening system of claim 32 wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 20:1.
34 . A method for thickening a composition comprising combining the composition with an effective amount of a thickening system comprising at least one cellulose ether and at least one network building polymer, wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 40:1, respectively.
35 . The method of claim 34 wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 20:1.
36 . The method of claim 34 wherein:
the at least one cellulose ether is selected from the group consisting of carboxymethyl cellulose (CMC), hydroxylethyl cellulose (HEC), ethyl hydroxylethyl cellulose (EHEC), methyl cellulose (MC), methyl hydroxylethyl cellulose (MHEC), hydroxypropylmethyl cellulose (HPMC) ethers, and any mixtures thereof; and
the at least one network building polymer is selected from the group consisting of gellan gum, carrageenan, pectin, alginate, agar, gelatin, and blends thereof.
37 . The method of claim 34 wherein the at least one cellulose ether is CMC and the at least one network building polymer is gellan gum.
38 . The method of claim 37 wherein the weight ratio of the at least one cellulose ether to the at least one network building polymer is from 4:1 to about 20:1.
39 . The method of claim 34 wherein the thickening system imparts a viscosity increase of at least 15% to the composition at 0.3 rpm as measured on a Brookfield viscometer.
40 . The method of claim 34 wherein the thickening system imparts at least a level of syneresis to the composition after being subject to a package stability test at 25° C. for 7 weeks as that exhibited by a composition comprising the same components, except for the presence of the network building polymer.
41 . The method of claim 34 wherein the thickening system is added to the composition in an amount from 0.1 to 5% by weight of the thickened composition.