Soluble, associative carboxymethylcellulose, method of making, and uses thereof

FIELD OF INVENTION

[0001] The present invention relates to water-soluble carboxymethylcelluloses (CMCs) that exhibit unique and highly desirable rheology and performance in end use systems and to a process for the preparation thereof. The CMCs of the present invention exhibit associative behavior both in neat solutions and in filled systems. The association is shear reversible, which enhances utility.

BACKGROUND OF THE INVENTION

[0002] Carboxymethylcellulose (CMC) is one of the most versatile and widely used cellulose ethers as a component for aqueous systems. It may act as a suspending agent, thickening agent, protective colloid, humectant, and for the control of crystallization of some other components. CMC is physiologically inert and is an anionic polyelectrolyte. The above noted characteristics makes CMC suitable for use in a wide spectrum of applications in the food, pharmaceutical, personal care, paper, building materials and construction, oilfield, and other industries.

[0003] There are many types of commercial CMCs available varying with respect to average degree of polymerization and substitution. The chemical and physical properties of the CMCs depend not only on the average degree of polymerization and substitution, but also on the overall solubility of the CMC as well as the distribution of carbomethoxy substituents along the cellulose chains. Both smoothly and blocky substituted CMCs are well known in the art. Blocky CMCs can be produced by lowering DS and/or changing the manufacturing process. However, processes that target a blocky CMC produce CMCs with limited solubility. In many cases a substantial portion of the CMC forms a swollen gel in aqueous applications. Such gels are undesirable in many applications, such as toothpaste, where the gel structure imparts an undesirable gel appearance in the toothpaste.

[0004] U.S. Pat. No. Re 32,976 discloses a smoothly substituted, enzyme and salt resistant CMC which is prepared using an etherification agent which comprises at least 50% isopropyl monochloroacetate. Smoothly substituted CMCs will not provide the associative properties of the current invention. The CMCs of the present invention are prepared from monochloroacetic acid or sodium chloroacetate, not isopropyl monochloroacetate.

[0005] U.S. Pat. No. 4,579,943 discloses a CMC that has high liquid absorbing property that is derived from regenerated cellulose, having cellulose II form. The CMCs are of relatively low DS (0.1-0.64) and are substantially insoluble in water. The CMCs of the current invention are derived from cellulose I, not cellulose II or regenerated cellulose.

[0006] Publication WO 99/20657 discloses a CMC that has a tan delta of less than 1.0 at a concentration of 0.5% under specific testing conditions. The CMC of the current invention do not have a tan delta less than 1.0 at 0.5% concentration.

[0007] The publication by G. Mann, J. Kunze, F. Loth and H-P fink of Fraunhofer Institut fur Angewandte Polymerforschung entitled “Cellulose ethers with a Block-like Distribution of the Substituents by Structure-selective Derivatization of Cellulose”, Polymer, vol. 39, No. 14, pp. 3155-3165, Published 1998, discloses the preparation and testing of block-like distribution of CMC. The CMC is prepared by a step-by-step etherification reaction where a systematic carboxymethylation in alcohol-water medium is conducted while maintaining a low NaOH concentration (NaOH/AGU molar ratio<0.6). The alkali cellulose is formed at elevated temperatures (50-70° C.). It is reported that this process produces block-like cellulose ethers, including CMC, or cellulose etheresters with alternating hydrophilic and hydrophobic as well as various ionic chain segments. The CMCs are swollen particles in water and are not substantially soluble. The CMCs of the present invention are produced at higher NaOH/AGU ratios (about 1.1 to about 1.9) and low alkali cellulose temperatures (20-30° C.), and are substantially soluble in water.

[0008] There is still a need for an associative, thixotropic CMC that exhibits associative behavior both in neat solutions and in filled systems. The association would be shear reversible, which would enhance utility. Such rheology would provide high thickening efficiency, and stabilize emulsions and suspensions, yet allow processing advantages such as ease of pumping or spreading, due to the reversible shear thinning characteristics of the associative network.

SUMMARY OF THE INVENTION

[0009] The present invention is related to a composition comprising CMC having a relative urea/water ratio of less than about 0.9. The relative urea ratio is defined as:

\begin{matrix} \begin{matrix} Relative Viscosity \\ in 6 M Urea \end{matrix} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in 6 M urea \end{matrix}}{6 M urea viscosity} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in 6 M urea \end{matrix}}{1.4 cP} \\ \begin{matrix} Relative Viscosity \\ in Water \end{matrix} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in Water \end{matrix}}{Water viscosity} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in 6 M urea \end{matrix}}{0.89 cP} \\ Relative Urea / Water Ratio = \frac{Relative Viscosity in 6 M Urea}{Relative Viscosity in Water} \end{matrix}

[0010] This invention is also directed to a process for making a CMC comprising a) reacting in an aqueous slurry of isopropyl alcohol, a source of cellulose, and about 50-80% of the stoichiometric level of alkali for a sufficient time and at a sufficient temperature to form an alkali cellulose b) adding sufficient alkali to bring the total alkali concentration to stoichiometric levels, followed by addition of the requisite amount of etherification agent, c) completing the etherification reaction and optionally, d) adjusting final molecular weight/viscosity by addition of oxidizing agents capable of degrading cellulosic chains.

[0011] This invention also comprehends the use of the CMC of the present invention in an aqueous rheology modifier system as a vehicle component of a personal care, household care, plaint, building material, construction, pharmaceutical, oilfield, food, paper making or paper coating composition.

BRIEF DESCRIPTION OF DRAWINGS

[0012]
FIG. 1 shows a graph of toothpaste viscosity over time.

[0013]
FIG. 2 shows a graph of toothpaste viscosity overtime that has been normalized.

[0014]
FIG. 3 shows a graph of toothpaste structure over time.

[0015]
FIG. 4 shows a graph of toothpaste structure over time that has been normalized.

[0016]
FIG. 5 shows a graph of crushing strengths of blends of polymers.

[0017]
FIG. 6 shows a graph of percent drug dissolved over time.

[0018]
FIG. 7 shows a graph of percent drug dissolved over time.

DETAILED DESCRIPTION OF THE INVENTION

[0019] A CMC has been surprisingly discovered that exhibits unique and highly desirable rheology and performance properties in end use systems.

[0020] In accordance with the present invention, the viscosity builds up not only by means conventional to CMC, but also is boosted significantly by molecular association. The association leads to network formation and gel-like rheological properties. The fact that the association is shear reversible enhances utility.

[0021] The CMCs of the present invention have been shown to lower the CMC use level needed and to provide rheology attributes unique from other CMCs available today. The unique rheology provides high thickening efficiency, and stabilizes emulsions and suspensions. The CMCs of the present invention provide significantly enhanced performance over known CMCs in aqueous systems including personal care formulations (e.g., toothpaste, skin care, and hair care), medical care (e.g., wound care and ostomy,), food applications (i.e., tortillas, cake mixes, bread mixes, bread, ice cream, sour cream, pasteurized processed cheese spreads, and cheese foods), beverages (i.e., instant cold/hot drinks, ready to drink beverages, and fruit flavored drinks), paint systems, building and construction materials (such as joint formulations), mineral processing, oil field formulations (e.g., drilling fluids), paper making and paper coating formulations, household formulations (e.g., laundry detergents, fabric softeners), and pharmaceutical formulations.

[0022] In accordance with the present invention, when the composition is a personal care composition, it includes (a) from about 0.1% to about 99.0% by weight of the vehicle component and (b) at least one active personal care ingredient. Examples of the at least one active personal care ingredient are deodorant, skin coolants, emollients, antiperspirant actives, moisturizing agents, cleansing agents, sunscreen actives, hair treatment agents, oral care agents, tissue paper products, and beauty aids.

[0023] In accordance with the present invention, the composition is a household care composition, it includes (a) from about 0.1% to about 99.0% by weight of the vehicle component and (b) at least one active household care ingredient. Examples of the at least one active household care ingredient are industrial grade bar, gel and liquid soap actives, all purpose cleaning agents, disinfecting ingredient, rug and upholstery cleaning actives, laundry softeners actives, laundry detergent ingredients, dishwashing detergents, toilet bowl cleaning agents and fabric sizing agents.

[0024] In addition to the ingredients conventionally used in the personal care and household care, the composition according to the present invention can optionally also include ingredients such as a colorant, preservative, antioxidant, nutritional supplements, activity enhancer, emulsifiers, viscosifying agents (such as salts, i.e., NaCl, NH4Cl & KCl, water-soluble polymers, i.e., hydroxyethylcellulose, and fatty alcohols, i.e., cetyl alcohol), alcohols having 1-6 carbons, and fats and oils.

[0025] The CMCs may also be used in combination with other known rheology modifiers including, but not limited to, polysaccharides (e.g., carrageenan, guar, hyaluronic acid, glucosaminoglycan, hydroxyethyl cellulose, hydrophobically modified hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, methylcellulose, cationic guar, carbomer), biopolymers (e.g., xanthan), synthetic polymers (polyethylene glycol, polyvinylacetate, chlorohexidiene), and thickening silicas.

[0026] The use of CMC in toothpaste formulations is well known in the toothpaste industry as a binder system for toothpaste that gives the toothpaste a desirable high structure. The binder system includes CMC types with other polysaccharides, inorganic salts, chelating agents and combinations thereof.

[0027] Commercially available CMC types vary in the degree of structure they provide to the toothpaste. Highly thixotropic grades of CMC tend to render toothpaste of higher structure. These thixotropic CMC types also tend to contribute to greater post-thickening.

[0028] Cellulose gum (CMC) alone has been a traditional binder for toothpaste. In toothpaste, CMC provides viscosity, stand-up or structure, and syneresis control. Toothpaste made with CMC is also known to have a slow rate in viscosity build up over the shelf life of the toothpaste thus not reaching a stable viscosity until after first 30 days or more. This is also called “post-thickening”.

[0029] Other binders commonly used in toothpaste are carrageenan or carrageenan and xanthan together. Carrageenan and xanthan provide good stand-up, viscosity and syneresis control; however, they tend to be more expensive alternatives as compared to CMC. Toothpaste made with carrageenan and xanthan tend to exhibit a stable viscosity rather quickly after processing and little post-thickening.

[0030] In accordance with the present invention, the CMC of the present invention can be use either alone or in combination with other polysaccharides, synthetic polymers and or salts and provide high efficiencies and enhanced performance. See the toothpaste Examples hereinafter for the demonstration of the unexpected results of the present invention.

[0031] Use of the CMCs of the present invention have allowed a use level reduction of about 40% while maintaining critical toothpaste properties such as stand-up, gloss and syneresis control. The lower use levels and/or shear thinning behavior of the CMCs may offer additional advantages to toothpaste properties such as improved flavor release, improved actives delivery, improved fluoride delivery, higher gloss, improved extrudability from the tube, and improved anti-microbial effectiveness. Potential improvements to the toothpaste manufacturing process include, but are not limited to, reduction of entrapped air during manufacturing process, improvements in mixing operations, and improvements in extrusion into tubes.

[0032] Water-based protective coating compositions (commonly referred to as paints) in which cellulose ether derivatives are conventionally used include latex paints or dispersion paints, of which the principal ingredients are film-forming lattices such as styrenebutadiene copolymers, vinyl acetate polymers and copolymers, and acrylic polymers and copolymers. Typically, they also contain opacifying pigments, dispersing agents and water-soluble protective colloids, the proportions being, by weight of the total composition, about 10 parts to about 50 parts of a latex, about 10 parts to about 50 parts of an opacifying pigment, about 0.1 part to about 2 parts of a dispersing agent, and about 0.1 part to about 2 parts of a water-soluble protective colloid.

[0033] Water soluble protective colloids conventionally used in the manufacture of latex paints (to stabilize the lattices and maintain the wet edge of a painted area longer in use) include casein, methyl cellulose, hydroxyethylcellulose (HEC), sodium carboxymethyl cellulose (CMC), polyvinyl alcohol, starch, and sodium polyacrylate. The disadvantages of the natural based cellulose ethers are that they may be susceptible to biological degradation and frequently impart poor flow and leveling properties, while the synthetic materials such as polyvinyl alcohol often lack enough thickening efficiency to maintain sag resistance. The thickening efficiency of the cellulose ethers is usually improved by increasing their molecular weight which normally is more expensive.

[0034] In accordance with the present invention, the CMC of the present invention can be used in lower amounts in paints and provide unexpected high quality results. This is illustrated in the working Examples hereinafter.

[0035] The CMCs of the present invention are prepared using conventional slurry process methods. For example, isopropyl alcohol, water, and about 50-80% of the stoichiometric amount of NaOH are reacted with cellulose at a temperature of about 20° C. for a sufficient time to produce alkali cellulose, about 1.5 hours. Sufficient NaOH is added to bring the total NaOH level to or slightly above stoichiometric levels and monochloroacetic acid is added shortly after the second NaOH addition. The reaction conditions are normally to raise the temperature to about 70° C. for about one to two hours to effect etherification. The molecular weight and viscosity of the CMC can be adjusted (reduced) by addition of an oxidizing agent, such as hydrogen peroxide, subsequent to etherification. The reaction mass is then optionally cooled, excess base neutralized, if necessary, and the product is washed. This product can then be dried and ground. The critical feature of this invention is that the amount of alkali utilized to effect etherification is less than stoichiometric and that the remaining alkali is added just prior to the etherification agent. The degree of substitution of the CMC is about 0.6 to about 1.2.

[0036] In accordance with the present invention, the CMC can be differentiated from prior art CMCs by their being substantially soluble in aqueous media environments and their behavior in environments that do not favor association. It is a known fact that urea breaks up association by breaking hydrogen bonds. The subject CMCs exhibit a viscosity decrease in the presence of urea, as determined by the relative urea ratio. The relative urea ratio is defined as:

\begin{matrix} \begin{matrix} Relative Viscosity \\ in 6 M Urea \end{matrix} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in 6 M urea \end{matrix}}{6 M urea viscosity} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in 6 M urea \end{matrix}}{1.4 cP} \\ \begin{matrix} Relative Viscosity \\ in Water \end{matrix} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in Water \end{matrix}}{Water viscosity} = \frac{\begin{matrix} Dynamic Viscosity of \\ 1 % CMC in 6 M urea \end{matrix}}{0.89 cP} \\ Relative Urea / Water Ratio = \frac{Relative Viscosity in 6 M Urea}{Relative Viscosity in Water} \end{matrix}

EXAMPLES

[0037] The following examples are merely set forth for illustrative purposes, but it is to be understood that other modifications of the present invention within the skill of an artisan in the related industry can be made without departing from the spirit and scope of the invention. All percentages and parts are by weight unless specifically stated otherwise.

Example 1

[0038] Isopropyl alcohol (IPA, 696.67 g) and deionized (DI) water (76.945 g) were charged into a jacketed resin kettle reactor equipped with an air driven stirrer, stainless steel agitator, a pressure equalizing addition funnel, a reflux condenser, vacuum, nitrogen inlet and a thermocouple. A cellulose pulp (65.0 g, 6.4% moisture) was added to the reactor, the reactor was sealed, and the agitator was adjusted to obtain good mixing. The reactor was inerted and the mixture was cooled to 20° C.

[0039] Aqueous NaOH (50%, 60.92 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 1 hour at 20° C. after the caustic addition was completed.

[0040] Aqueous NaOH (50%, 16.02 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 5 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 42.91 g) was added to the reactor through an open reactor port, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1.5 hours. The reaction slurry was filtered and the resulting wet cake was washed three times with 565 g of 80% aqueous methanol and one time with 1000 g of pure methanol. The resulting wet cake was broken into small particles and dried in a fluidized bed dryer for 35 minutes. (Air-dry for 5 minutes, heat-dry at 50° C. for 10 minutes, and heat-dry at 70° C. for an additional 20 minutes.) The product was ground in Retsch Grinding Mill using a 1 mm screen. Degree of Substitution (DS)=0.89

Example 2

[0041] Isopropyl alcohol (IPA, 696.67 g) and deionized (DI) water (76.945 g) were charged into a jacketed resin kettle reactor equipped with an air driven stirrer, stainless steel agitator, a pressure equalizing addition funnel, a reflux condenser, vacuum, nitrogen inlet and a thermocouple. A cellulose pulp (65.0 g, 6.4% moisture) was added to the reactor, the reactor was sealed, and the agitator was adjusted to obtain good mixing. The reactor was inerted and the mixture was cooled to 20° C.

[0042] Aqueous NaOH (50%, 60.92 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 1 hour at 20° C. after the caustic addition was completed.

[0043] Aqueous NaOH (50%, 16.02 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 5 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 42.91 g) was added to the reactor through an open reactor port, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1.5 hours. 1.6 ml of 6% H2O2 was added to the reactor and the slurry was heated at 70° C. for 30 minutes. The reaction slurry was filtered and the resulting wet cake was washed three times with 565 g of 80% aqueous methanol and one time with 100 g of pure methanol. The resulting wet cake was broken into small particles and dried in a fluidized bed dryer for 35 minutes. (Air-dry for 5 minutes, heat-dry at 50° C. for 10 minutes, and heat-dry at 70° C. for an additional 20 minutes.) The product was ground in Retsch Grinding Mill using a 1 mm screen. Degree of Substitution (DS)=0.87.

Example 3

[0044] Isopropyl alcohol (IPA, 123.4 gallons), water (130.3 lbs), methanol (6.36 gallons), and NaOH (flake, 35.4 lbs.) were charged into the reactor. The reactor was inerted and the caustic/solvent mix was cooled to about 20° C., at which time a cellulose pulp (108 lbs, 4% moisture) was added to the reactor. The agitation was adjusted to give good mixing in the slurry and the slurry was recooled to about 20° C. The reaction slurry was held for 1 hour at 20° C.

[0045] Aqueous NaOH (50%, 58.7 lbs.) was added to the reactor and the reaction mixture was held for 15 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 70.5 lbs.). IPA (9.0 gallons), dichloroacetic acid (DCA, 926.8 g) and acetic acid (79.9 g) were added to the reactor, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1 hour. 282 g of 18% H2O2 was added to the reactor and the slurry was heated at 70° C. for 60 minutes.

[0046] The reaction slurry was centrifuged and the wet cake was washed with three times with 300 gallons of 80% methanol and two times with 300 gallons 100% methanol. The material was dried in an Abbe dryer under vacuum at 80-90° C. to a moisture content of 4-6%. The product was ground in a micropulverizer through a 0.0278 inch screen. Degree of Substitution (DS)=0.79.

Example 4

[0047] The conditions of Example 3 were repeated. DS=0.78

Example 5

[0048] Isopropyl alcohol (IPA, 121.9 gallons), water (130.0 lbs), methanol (6.29 gallons), and NaOH (flake 45.6 lbs.) were charged into the reactor. The reactor was inerted and the caustic/solvent mix was cooled to about 20° C., at which time a cellulose pulp (108 lbs, 4% moisture) was added to the reactor. The agitation was adjusted to give good mixing in the slurry and the slurry was recooled to about 20° C. The reaction slurry was held for 1 hour at 20° C.

[0049] Aqueous NaOH (50%, 58.7 lbs.) was added to the reactor and the reaction mixture was held for 15 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 81.0 lbs.). IPA (9.0 gallons), dichloroacetic acid (DCA, 1065.9 g) and acetic acid (91.9 g) were added to the reactor, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1 hour. 188 g of 18% H2O2 was added to the reactor and the slurry was heated at 70° C. for 60 minutes.

[0050] The reaction slurry was centrifuged and the wet cake was washed with three times with 300 gallons of 80% methanol and two times with 300 gallons 100% methanol. The material was dried in an Abbe dryer under vacuum at 80-90° C. to a moisture content of 4-6%. The product was ground in a micropulverizer through a 0.0278 inch screen. Degree of Substitution (DS)=0.86.

Example 6

[0051] The conditions of Example 5 were repeated. DS=0.86

Example 7

[0052] Isopropyl alcohol (IPA, 121.1 gallons), water (146.0 lbs), methanol (6.24 gallons), and NaOH (flake, 35.4 lbs.) were charged into the reactor. The reactor was inerted and the caustic/solvent mix was cooled to about 20° C., at which time a cellulose pulp (108 lbs, 4% moisture) was added to the reactor. The agitation was adjusted to give good mixing in the slurry and the slurry was recooled to about 20° C. The reaction slurry was held for 1 hour at 20° C.

[0053] Aqueous NaOH (50%, 58.7 lbs.) was added to the reactor and the reaction mixture was held for 15 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 70.5 lbs.). IPA (9.0 gallons), dichloroacetic acid (DCA, 926.8 g) and acetic acid (79.9 g) were added to the reactor, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1 hour. 282 g of 18% H2O2 was added to the reactor and the slurry was heated at 70° C. for 60 minutes.

[0054] The reaction slurry was centrifuged and the wet cake was washed with three times with 300 gallons of 80% methanol and two times with 300 gallons 100% methanol. The material was dried in an Abbe dryer under vacuum at 80-90° C. to a moisture content of 4-6%. The product was ground in a micropulverizer through a 0.0278 inch screen. Degree of Substitution (DS)=0.79.

Example 8

[0055] Isopropyl alcohol (IPA, 14 kg), water (2184 g), methanol (728.8 g), were charged into the reactor. The reactor was inerted and the solvent mix was cooled to about 20° C., at which time a cellulose pulp (1800 g, 3.6% moisture) was added to the reactor. The agitation was adjusted to give good mixing in the slurry, the slurry was recooled to about 20° C., and NaOH (flake, 691.4 g) was added to the reactor. The reaction slurry was held for 1 hour at 20° C.

[0056] Aqueous NaOH (50%, 353.6 g) was added to the reactor and the reaction mixture was held for 15 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 939.8 g). IPA (977 g), dichloroacetic acid (DCA, 27.3 g) and acetic acid (2.4 g) were added to the reactor, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1 hour.

[0057] The reaction slurry was filtered, and the resulting wet cake was washed three times with 12 gallons of 80% aqueous methanol, and one time with 12 gallons of 95% methanol. The material was dried in a vacuum tray dryer at 70° C. to a final moisture content of 4-6%. The dried product was ground in a micropulverizer through a 0.0278 inch screen. Degree of Substitution=0.73.

Example 9

[0058] Isopropyl alcohol (IPA, 696.67 g) and deionized (DI) water (76.95 g) were charged into a jacketed resin kettle reactor equipped with an air driven stirrer, stainless steel agitator, a pressure equalizing addition funnel, a reflux condenser, vacuum, nitrogen inlet and a thermocouple. A cellulose pulp (65.0 g, 6.8% moisture) was added to the reactor, the reactor was sealed, and the agitator was adjusted to obtain good mixing. The reactor was inerted and the mixture was cooled to 20° C.

[0059] Aqueous NaOH (50%, 60.92 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 1 hour at 20° C. after the caustic addition was completed.

[0060] Aqueous NaOH (50%, 36.37 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 5 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 42.91 g) was added to the reactor through an open reactor port, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1.5 hours. 1.6 ml of 6% H2O2 was added to the reactor and the slurry was heated at 70° C. for 30 minutes. The reaction slurry was filtered and the resulting wet cake was washed three times with 565 g of 80% aqueous methanol and one time with 1000 g of pure methanol. The resulting wet cake was broken into small particles and dried in a fluidized bed dryer for 35 minutes. (Air-dry for 5 minutes, heat-dry at 50° C. for 10 minutes, and heat-dry at 70° C. for an additional 20 minutes.) The product was ground in Retsch Grinding Mill using a 1 mm screen. Degree of Substitution (DS)=0.62. 1% aqueous viscosity=2200 cps.

Example 10

[0061] Isopropyl alcohol (IPA, 713.86 g) and deionized (DI) water (73.79 g) were charged into a jacketed resin kettle reactor equipped with an air driven stirrer, stainless steel agitator, a pressure equalizing addition funnel, a reflux condenser, vacuum, nitrogen inlet and a thermocouple. A cellulose pulp (65.0 g, 3.7% moisture) was added to the reactor, the reactor was sealed, and the agitator was adjusted to obtain good mixing. The reactor was inerted and the mixture was cooled to 20° C.

[0062] Aqueous NaOH (50%, 39.98 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 1 hour at 20° C. after the caustic addition was completed.

[0063] Aqueous NaOH (50%, 35.77 g) was slowly added to the reactor through the addition funnel, maintaining the mixture slurry temperature at 20° C. The reaction mixture was held for 5 minutes at 20° C. after the caustic addition was completed. Monochloroacetic acid (MCA, 42.25 g) was added to the reactor through an open reactor port, maintaining a reactor slurry temperature of 20° C. After MCA addition was completed, the reaction slurry was heated to 70° C. and held for 1.5 hours. The reaction slurry was filtered and the resulting wet cake was washed three times with 565 g of 80% aqueous methanol and one time with 1000 g of pure methanol. The resulting wet cake was broken into small particles and dried in a fluidized bed dryer for 35 minutes. (Air-dry for 5 minutes, heat-dry at 50° C. for 10 minutes, and heat-dry at 70° C. for an additional 20 minutes.) The product was ground in Retsch Grinding Mill using a 1 mm screen. Degree of Substitution (DS)=0.84. 1% aqueous viscosity=3760 cps.

Example 11

[0064] This Example illustrates the behavior of the preparations of a 1.0% CMC samples of the present invention in a 6.0 M urea solution.

[0065] The 1% CMC solution was prepared in the following equipment:

[0066] Caframo RZR1 overhead stirrer, 8-oz. glass jars, stainless steel stirring shaft with two 3-blade propellers (1.5 inch diameter), Parafilm®, deionized (DI) water, Germaben II.

[0067] A 0.50% Germaben solution was prepared by adding the Germaben II to DI water. This solution was then weighed into an 8-oz. glass jar. The solution was then stirred with an overhead stirrer, while the CMC was quickly added to the solution. The CMC level is 1.0% of the final sample weight. CMC weight is corrected for moisture content. As the viscosity begins to increase, the speed of the stirrer was increased to the maximum rate that does not cause splashing out of the sample. The jar is covered with Parafilm while mixing to prevent evaporation of water and loss from splashing. The sample is stirred for one hour. After one hour of stirring at the highest rate, the stirring speed was decreased to a setting of 4 for one additional hour. The sample was centrifuged for approximately 5 minutes to remove trapped air.

[0068] The behavior of the samples were studied in the following equipment:

[0069] Caframo RZR1 overhead stirrer, 8-oz. glass jars, stainless steel stirring shaft with two 3-blade propeller (1″ diameter), Parafilm®, 6.0M Urea (180.18 g urea diluted to 500 ml)

[0070] Procedure:

[0071] 6.0M urea solution was weighed into an 8-oz. glass jar. The solution was stirred with an overhead Caframo RZR1 stirrer, as the CMC was quickly added to the solution. The CMC level was 1.0% of the final sample weight. CMC weight was corrected for moisture content. As the viscosity begins to increase, the speed of the stirrer was increased to the maximum rate that does not cause splashing out of the sample. The jar was covered with Parafilm while mixing to prevent evaporation of water and loss from splashing. The sample was stirred for one hour. After one hour of stirring at the highest rate, the stirring speed was decreased to a setting of 4 for one additional hour. The sample was centrifuged for approximately 5 minutes to remove trapped air.

1TABLE 11%1%DynamicDynamicWater6M UreaRelativeCMCDSviscosityviscosityU/W ratioExample 80.73111313640.78Example 10.895746320.70Example 20.872382880.77Example 70.797625390.45Example 50.862653380.81Example 30.792863550.79Example 40.783463980.73Example 60.861632280.89Aqualon 7LF0.8111160.97Aqualon 7LF11170.96Aqualon 7L0.799140.97Aqualon 7H3SF0.977191127541.13Aqualon 7H3SF0.92228641791.16Aqualon 7H3SF0.887337132581.15Aqualon 7H3XSF0.89326259091.15Aqualon 7H3SXF311149501.01Aqualon 7HF0.867023116481.05Aqualon 7H4F0.77487585761.12Aqualon 7M8SF681111.03Aqualon 9M31F0.92604671.14Aqualon 9M31F0.9257710651.17Aqualon 9M31F0.95398230.97Aqualon 9M31XF2824701.06Amtex1682821.07Antisol FL285285101.90300000Aqualon7795125831.03AquapacAqualon11446198811.10AquapacDKS Cellogen1001791.14HE-90DKS Cellogen441781541.17HP-5HSFine Gum SA-H46310161.40Monpac Regular275559801.38Noviant Cekol47680.92500TNoviant Cekol53961.16700Noviant Cekol1392461.132000PAC-R7335117981.02Tylopur C10003165581.12P2Walocel CRT1802851.012000

Example 12

[0072] Dynamic viscosities were measured using at 25° C. using an RFS III strained controlled rheometer by Rheometrics using a 40 mm parallel tool geometry with the gap set at 2 mm. The samples were pre-sheared at 100 s−1 for 60 second upon loading to erase the loading history. The pre-shearing was followed by the steady shear experiment between 0.01 and 100 s−1. Each point data is the average of clockwise and counter-clockwise rotations each with the duration of 20 sec. All samples exhibited a low shear Newtonian plateau, the average of which was used in the data analysis and further comparisons. The dynamic viscosities of the aqueous and 6M 1% CMC solutions are summarized in Table 1. The relative urea/water ratios are also summarized in Table 1, above.

Example 13

[0073] The CMC's of the present invention exhibit enhanced thickening capabilities and syneresis control in toothpaste formulations. Calcium Carbonate Based Toothpaste formulation:

2Ingredient:wt. %Calcium carbonate45.00Sorbo ® sorbitol (70% solids)27.00Distilled water23.97CMC Polymer (Table 2)0.60Sodium lauryl sulfate, 100% active powder1.00Sodium monofluorophosphate0.76Sodium benzoate0.50Flavor0.55Tetra sodium pyrophosphate0.42Sodium saccharin0.20100.00

[0074] Standard laboratory toothpaste preparation was performed. Salts were first dissolved in part of the water and warmed for complete dissolution. The CMC was dispersed in the sorbitol, using an overhead mixer with a propeller attachment. After the CMC was well dispersed, the balance of the water was added with continued mixing until the CMC appeared dissolved. The warm salt solution was mixed into the CMC solution. This was then transferred to a 1-quart Ross double planetary mixer. The calcium carbonate was then stirred in the mixer, and after it was well dispersed, a vacuum was applied. After mixing under vacuum for 20 minutes, the sodium lauryl sulfate was mixed in without vacuum.

[0075] The flavor was mixed in the same way. After all formula components were together, the mixture was mixed under vacuum for 15 minutes at high speed. The batch was then packed into 2-oz. jars and 6-oz. toothpaste tubes.

[0076] Toothpaste samples were stored for 30 days at room temperature. Samples were equilibrated in a 25° C. water bath for 4 hours prior to any tests conducted.

[0077] Viscosity was measured using a Brookfield DV-I fitted with a T-bar style spindle. A helipath stand was used to allow the spindle to sweep downward through the sample to prevent the effects of shear. Viscosity was taken every 30 seconds over 2 minutes and values were averaged.

[0078] Toothpaste consistency was measured using a rack test. The rack designed with cross bars of increasing distance apart left to right. The toothpaste tube containing the sample to be measured is fitted with a stainless orifice fitting to eliminate differences in orifice size that may occur. The tube is squeezed in a uniform manner across the rack, extruding the paste onto the rack in a ribbon. After 15 seconds it is recorded at which opening the ribbon has fallen through the opening and broken. The opening number from left to right is the value recorded as a “Cuban” value.

[0079] The toothpaste data are summarized in Table 2.

3TABLE 230 dayToothpastePolymerViscosityCubanCommentsExample 21375005Example 118812510Example 31467506Example 41362506Example 51200005Example 6945003Example 71257505Cekol 500T618752Cekol 2000258750severesyneresis9M31XFGL401250syneresis9M31F325000syneresis

Example 14

[0080] The CMC's of the present invention in combination with other polymers exhibit decreased post thickening and structure build and enhanced initial structure in toothpaste formulations.

[0081] Viscosity is one measure of post-thickening in toothpaste. Toothpaste samples were packed into vials and the viscosity was measured using a Brookfield DV-I fitted with a T-bar style spindle. A helipath stand was used to allow the spindle to sweep downward through the sample to prevent the effects of shear. Viscosity was taken every 30 seconds over 2 minutes and values were averaged

[0082] It can be seen from the data in the graph (FIG. 1) that most samples exhibited a change in viscosity from the first day after processing through 30 days. When the data are normalized to the initial viscosity as 100%, the change over time is more apparent (FIG. 2). Toothpaste made with combinations of Example 7 CMC with other polysaccharides or inorganic salts exhibited lower post-thickening compared to toothpaste made with Example 7 alone.

[0083] Toothpaste structure is also an important aspect. This property may be measured by force required for compression using a MTS Servo Hydraulic test system from MTS Systems Corporation, Minneapolis, Minn. The instrument was fitted with a half-inch acrylic cylinder probe, toothpaste samples were packed into vials after processing and measured directly without disturbance.

[0084] It can be seen below in Table 3 that the Example 7 CMC alone or with other polysaccharides or inorganic salt produced toothpaste of similar or greater initial structure compared to toothpaste made with carrageenan and xanthan and much greater initial structure than toothpaste made with commercial CMC 9M31F.

[0085] Peak force of compression was monitored over 30 days. It was found that most samples changed in values (FIG. 3). The comparison can be made more

[0086] easily if the data are normalized to the initial structure value as 100% as shown in FIG. 4. From the normalized data of FIG. 4, it can be seen that toothpaste samples made with combinations of CMC of Example 7 with other polysaccharides or inorganic salt have lower structure build over time.

[0087] From the work outlined here, it can be concluded that toothpaste with high structure and low post-thickening can be made with CMCs of the present invention in combination with other polysaccharides, inorganic salts or combinations thereof.

[0088] The toothpaste formulation used in this Example was as follows:

4IngredientWt. %Sorbitol (Sorbo)29.2Glycerine6PEG 4003Sident 914Sident 22S16Sodium Saccharine0.20Sodium Monofluorophosphate0.23Sodium Benzoate0.20Sodium Lauryl Sulfate1.20Flavor0.50Waterq.s.

[0089] The different polymers used in this Example in the formulation was as follows:

5FormulationPolymer:wt %Polymer:wt %1Carrageenan (THP1)0.7Xanthan (Rhodicare)0.32CMC Example 71.0N/A3CMC 9M31F1.0N/A4CMC Example 70.5Natrosol + 3300.35CMC Example 70.6Natrosol 250 M0.66CMC Example 70.7Carrageenan0.37CMC Example 71.0Sodium Silicate0.58CMC Example 70.7Xanthan0.3

[0090]

6

TABLE 3

Initial Toothpaste Structure

Peak Force Compression from MTS

Peak Force

Polymer
Compression, g

Carageenan/Xanthan
56.5

Example 7
51.1

Example 7/HMHEC
78.1

Example 7/Na2SiO3
60.8

Example 7/HEC
75.1

Example 7/Carrageenan
75.3

Example 7/Xanthan
35.0

CMC 9M31 F
14.7

Toothpaste after 24 hours, ambient temperature.

[0091] The identity and supplier of the ingredients of this Example are as follows:

7SorbitolSorbo, 70%, USP/FCC, SPI Pharma,New Castle, DE, USAGlycerineGlycerine, USP, Spectrum Chemical,Gardena, CA, USAPEG 400Polyethylene Glycol NF, Dow Chemical,Midland, MI, USASilica, thickeningSident 9, Degussa, Frankfurt, GermanySilica, abrasiveSident 22S, Degussa, Franfurt, GermanySodium Lauryl SulfateStepan, Northfield, IL, USAFlavorFresh Mint, Givaudan, UKSodium Silicate, crystallineJT Baker, reagent gradeSodium BenzoateFisher Scientific, reagent gradeSaccharineSigma, reagent gradeSodium FluorophosphateAlfa Aesar, Ward Hill, ME, USACarrageenanTHP1, CP Kelco, San Diego, CA, USAXanthanRhodicare S, Rhodia, Cranbury NJ, USACMC 9M31FAqualonHM HEC Natrosol PlusAqualon330 CSHEC Natrosol 250 M PharmAqualon

Example 15

[0092] The CMC's of the present invention exhibit enhanced thickening capabilities in beverage formulations.

Beverage Example

[0093] Orange Beverage—Reference

8IngredientsWt %Orange Juice concentrate, 45 Brix7.00Sugar40.00Citric acid0.05Sodium benzoate0.55Water52.14Cellulose Gum, CMC-9M31F0.60

Orange Beverage—Test Example

[0094]

9

Ingredients
Wt %

Orange Juice concentrate, 45 Brix
7.00

Sugar
40.00

Citric acid
0.05

Sodium benzoate
0.55

Water
52.14

Polymer Example 7
0.42

[0095] Mix cellulose gum or polymer into water, allow to mix for 20 minutes. Premix acid, preservative and sugar, add and mix 5 minutes. Add juice concentrate, mix 3 minutes.

10Beverage results:ReferenceTest ExampleViscosity, 24 hours, cps53.051.0Brookfield LV, spindle 2, 30 rpm, 20 s

Example 16

[0096] The CMC's of the present invention exhibit enhanced thickening capabilities in food formulations.

Cake Mix and Cake Example

[0097] Cake Mix—Reference

11Ingredients for Dry Mix% Flour wtWt % of dry mixBleached Cake Flour10040.4Sugar105.942.2Shortening27.211.0Milk Solids Nonfat3.71.5Dextrose(1)2.51.0Salt2.51.0Sodium Bicarbonate(2)2.20.9Sodium aluminum phosphate(3)1.20.9Vanilla Powder(4)1.20.5Butter Flavor(5)0.30.1Cellulose Gum, CMC-7HF1.20.5

Cake Mix—Test Example

[0098]

12

% Flour
Wt % of

Ingredients for Dry Mix
wt
dry mix

Bleached Cake Flour
100
40.4

Sugar
105.9
42.2

Shortening
27.2
11.0

Milk Solids Nonfat
3.7
1.5

Dextrose(1)
2.5
1.0

Salt
2.5
1.0

Sodium Bicarbonate(2)
2.2
0.9

Sodium aluminum phosphate(3)
1.2
0.9

Vanilla Powder(4)
1.2
0.5

Butter Flavor(5)
0.3
0.1

Polymer Example 9
0.72
0.3

(1)
Arm & Hammer Baking Soda, Church & Dwight

(2)
Cantab Dextrose, Penford Food Ingredient Company

(3)
Levair, FCC Grade Sodium Aluminum Phosphate, Rhodia Food Ingredients

(4)
Vanilla FL Pure Pwd K, Virginia Dare

(5)
Butter FL N&A Pwd 685 KD, Virginia Dare

[0099]

13

Formulation for the Finished Cake - One 8-inch Layer

Dry mix, g
270

Water, g
140

Whole egg, g
53

[0100] Dry ingredients were blended on mixer with paddle attachment until evenly mixed. Water and egg were added to mix and mixed on medium speed for 3 minutes. The batter was poured into a greased cake pan and baked in a moderate oven (350° F./177° C.) for 30 minutes.

14Cake results:ReferenceTest ExampleBatter Viscosity, cps56607650Brookfield RV, spindle 3, 10 rpm, 30 sBatter density, g/100 mls111113Cake height, cm3.83.8Crumb cell structureevenevenBake outOKOKCrumb moisture, 24 hours after bake, %39.039.0

Example 17

[0101] The CMCs of the present invention exhibit efficiency by the use of reduced amounts but yet obtain corporate results with prior art materials. The film forming and viscosity properties are enhanced in food preparations.

Masa and Corn Tortilla Example

[0102] MASA—Reference

15% FlourWt % ofIngredients for Dry Mixwtdry mixNCF(1)10098.83Sodium Benzoate0.40.39Fumaric Acid0.30.29Cellulose Gum, CMC-7H4F K0.50.49

MASA—Test Example

[0103]

16

% Flour
Wt % of

Ingredients for Dry Mix
wt
dry mix

NCF(1)
100
98.63

Sodium Benzoate
0.4
0.39

Fumaric Acid
0.3
0.29

Polymer Example 10
0.3
0.29

(1)
Nixtamalized corn flour, Quaker Oats Company

[0104] Dry ingredients were blended on mixer with paddle attachment until evenly mixed. Water was added to mix and mixed on medium speed for 2 minutes. Dough was portioned into 50 g balls and pressed on a tortilla press. The tortillas were baked on an ungreased skillet for 1 minutes on each side. Tortillas were cooled on a wire rack, wrapped in foil sheets and checked for pliability and reheat after 1 day.

17Tortilla results:ReferenceTest ExampleAppearance after bakeeven blisterseven blistersPliabilitygood roll, no cracksgood roll, no cracksReheatgood puffgood puff

Example 18

[0105] The CMC's of the present invention exhibit enhanced tablet crushing strength without effecting drug release kinetics.

[0106] The following formulations were prepared:

18Total batch size1500 g3750 TabletsMaterial%Wt per Tab (Mg)Example 77.530Klucel HXF22.590Phenylpropanolamine20.080Avicel PH10149.5198Magnesium Stearate0.52Example 77.530Natrosol 250 HX22.590Theophylline20.080Avicel PH10149.5198Magnesium Stearate0.52CMC 12M8 PH7.530Klucel HXF22.590Phenylpropanolamine2080Avicel PH10149.5198Magnesium Stearate0.52CMC 12M8 PH7.530Natrosol 250 HX22.590Theophylline2080Avicel PH10149.5198Magnesium Stearate0.52

[0107] Experimental Procedures:

[0108] All ingredients were sieved through a 20 mesh screen. All ingredients except magnesium were then dry blended in a 4 quart low shear Hobart mixer for 2 minutes. Thereafter water was added at a rate of 100 g/min while using low speed stirring. A total of 500 ml per 1500 g of powder was added to the formulations containing Klucel. This was increased to 700 g for Natrosol containing formulations. The wet masses were tray dried at 60° C. down to less than 2% moisture content. Following the drying step, the granulations were milled using the Fitzpatrick Comminutor Fitzmill at 2300 rpm, knives forward. The reduced granulation was then lubricated by addition of 0.5% magnesium stearate. This final mix was blended for 3 minutes in a V-blender.

[0109] Compactibility:

[0110] As shown in FIG. 5 for both model formulations, the inclusion of Example 7 CMC in place of CMC 12M8 pH in the tablet matrix results in a significant increase in tablet crushing strength.

[0111] Drug Release Kinetics

[0112] While compactibility is improved, inclusion of Example 7 CMC does not manifest in significant differences in the release kinetics when compared to 12M8 pH. This shown in FIGS. 6 and 7 for both highly soluble drug (phenylpropanolamine) and a sparingly soluble drug (Theophylline). Additionally no differences were evident at pH 1.5 or 6.8 between the Example 7 CMC and CMC 12M8 containing formulations.

Example 19

[0113] The CMC's of the present invention exhibit enhanced thickening efficiency, enchanced high shear viscosity (ICI), improved spatter resistance and improved water resistance in paint formulations.

[0114] Model of an Interior Latex Flat Paint Based on Acronal 290 D.

19IngredientsFunctionParts by weightPosition 1.Water230.0 2.Calgon Nwetting agent1.5 3.Pigmentverteiler Adispersing agent3.0 4.CA 24preservative3.0 5.Agitan 280defoamer5.0 6.thickenerrheological modifiervariablepre-mix 7.Kronos 2057pigment198.0 8.Omyalite 90extender140.0 9.Durcal 5extender198.010.Talcom AT 200extender28.0mill base11.Acronal 290 Dlatex binder93.013.butylglycolcoalescing agent20.014.Texanol5.015.additional water71.5let downPVC (%)80%NVW (%)61%

[0115] Suppliers:

[0116] 2 Benckiser Knapsack GmbH

[0117] 3 BASF AG

[0118] 4 Biochema Schwaben—Dr. Lehmann & Co.

[0119] 5 Munzing Chemie GmbH

[0120] 6 Aqualon/HERCULES

[0121] 7 Kronos Titan GmbH

[0122] 8 Pluss Staufer SG

[0123] 9 Pluss Staufer SG.

[0124] 10 a/s Norwegian Talc

[0125] 11 BASF AG

[0126] 12 Shell Nederland Chemie BV

[0127] 13 Eastman Chemicals

20SagWaterTEBrookfield (20/4)StormerStormerICILevelling1Leveling1resistanceSpatter1reten.2Thickener[wt %]24 hrs [mPa · s]Initial [KU]24 hrs [KU][mPa · s]LenetaNYPC[μm]resistance[mm]BLANOSE ® 7M31C0.57705098106125506002-34BLANOSE ® 7M31C0.46675097103120406002-35BLANOSE ® 7M31C0.456500971041502055034Example 7 CMC0.417550971071501060043Rating 10-10, 10 = BEST 2Water resistance test acc. Grimshaw; 0 mm = best

[0128] ICI Viscosity Determination: Determined using ASTM D4287-83

[0129] Krebs Stormer Viscosity Measurement: Determined using ASTM D 562

[0130] Levelling Leneta: Determined using ASTM D 4062-81

[0131] Levelling test NYPC: Determined using ASTM D 2801-69

[0132] Sag Resistance: Determined using ASTM D4400-84

[0133] Spatter Resistance—Roller:

[0134] The following equipment was used to evaluate the samples:

[0135] paint roller with synthetic fibers e.g. verfroller 15 cm art.nr. 32913 ex Van Vliet Kwastenfabriek

[0136] wall paper (woodchip quality) e.g. Erfurt Raufaser 52

[0137] Procedure:

[0138] About 200 grams of paint is taken up by the roller. Paint is applied on a woodchip wallpaper with dimensions 100×50 cm placed in vertical position. Paint is applied by ten-up and down strokes with the roller. A piece of black carch paper is placed horizontally 50 cm below the bottom line of the wallpaper. The amount of spatter that is intercepted on the black paper is compared to a series of reference charts rating from 1 to 10. A rating of 1 means severe spatter and a rating of 10 stands for completely spatter free.

[0139] Water Retention (According GRIMSHAW)

[0140] Equipment used in this part of the experment is:

[0141] Substrate: Whatman No.1 circular

[0142] Filter paper (diameter 12.5 cm)

[0143] Clamp ring inner diameter 7.7 cm outer diameter 12.6 cm

[0144] Pasteur pipette (poly ethylene disposable)

[0145] Colorant: Quink parket permanent block ink

[0146] Balance

[0147] Procedure

[0148] 1. Mix a blend of paint/colorant thoroughly in an aluminum cup. Depending on the viscosity the following ratio's can be chosen:

21Paint:colorant50:5060:4075:25Total amount 4-5 grams

[0149] 2. Put the filter paper between two clamp rings and fix these with paper clips.

[0150] 3. Weigh the clamped filter paper and apply with a Pasteur pipette 0.5 or 1.0 gram (depending the fluidity of the colored point blob) on the center of the filter paper.

[0151] 4. Allow an overnight drying at room temperature.

[0152] 5. Measure with a ruler the shaded stain round the paint center on 6 different spots.

[0153] 6. The average expressed in mm is a measure for the water retention. A low value means a good water retention.

[0154] 7. Report the used test conditions, ratio and amount of paint as well as the increase of the stain in mm.

[0155] While this invention has been described with respect to specific embodiments, it should be understood that these embodiments are not intended to be limiting and that many variations and modifications are possible without departing from the scope and spirit of this invention.

Soluble, associative carboxymethylcellulose, method of making, and uses thereof

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CPC

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Provisional Applications (1)