PROCESS FOR MAKING NON-STAINING COLORED PARTICLES FOR IMPROVING AESTHETICS OF A LIQUID AUTOMATIC DISHWASHING DETERGENT PRODUCT, THE PARTICLES, AND A COMPOSITION

Abstract: A process for forming a non-staining colored composite particle suitable for incorporation in a bleach-containing or a non-bleach-containing liquid detergent composition is disclosed. The process includes the steps of forming a colored liquid dispersion of pigment particles in a first liquid medium wherein the size of the pigment particles in the colored liquid dispersion is no greater than about 5 mu m. The process includes the step of mixing the colored liquid dispersion with a polymeric material and a second liquid medium to form a sprayable colored polymeric material. The process also includes the step of spraying the colored polymeric material on a composite particle and forming a colored polymeric coating on the composite particle. A non-staining colored particle and a liquid ADW detergent composition are also disclosed.

Description: PROCESS FOR MAKING NON-STAINING COLORED PARTICLES FOR IMPROVING AESTHETICS OF A LIQUID AUTOMATIC DISHWASHING DETERGENT PRODUCT. THE PARTICLES. AND A COMPOSITION TECHNICAL FIELD The present invention generally relates to liquid automatic dishwashing detergent compositions. More particularly, the invention relates to a process for making colored particles that can be incorporated into a bleach-contammg or non-bleach-contammg liquid automatic dishwashing detergent composition for improving the aesthetics of the liquid composition wherein the colored particles do not stain the plastic surfaces of dishware or an automatic dishwasher. BACKGROUND OF THE INVENTION Consumers of liquid ADW products have a preference for such products having a certain color or appearance. The addition of solid particles suspended into a liquid ADW composition can improve the aesthetics of the product by simply improving the physical appearance of the product. This is particularly true if the particles are colored and their color is matched effectively to the base color of the liquid ADW composition. Previously used particles in liquid ADW products have had a major disadvantage of contributing negatively to unwanted filming, particularly on glass, stainless steel and plastic surfaces. This is because the previously used particles have been coated with water-msoluble coatings, such as waxes, which melt and are released into the wash solution due to the high temperature encountered during the automatic dishwashing process. Further, in the arena of bleach containing liquid ADWs, the particles cannot be colored by simply using a dye, because duπng storage of the liquid ADW product, the dye gets bleached Thus, the formulators have to use bleach-safe pigments to impart an aesthetically pleasing color Before this invention, the incorporation of pigments posed a major problem: the color of the pigment is found to detrimentally stain plastic surfaces, such as plastic dishware and the internal plastic surfaces of a dishwasher. It has been desirable to have a process by which colored pigment based particles can be made for incorporation m bleach-contammg or non-bleach-contaming liquid ADW product, such that the particles are non-stammg. It has also been desirable that the solid particles do not dissolve in the liquid ADW product, but dissolve rapidly in the wash solution duπng automatic dishwashing. It has been desirable to have a liquid ADW product having solid particles that do not cause a significant amount of unwanted filming on glass, stainless steel and plastic. The inventors of the present invention have discovered a process of coating the particles with a pigment in a manner such that the particles are non-stammg. This invention is not limited to just bleach-contammg liquid ADWs and is also applicable to non-bleach-contammg liquid ADWs that are incorporated with prills or particles colored with pigments. The present invention is thus directed to overcome one or more of the problems as set forth before. SUMMARY OF THE INVENTION The invention meets the needs above by providing a process for forming a non-stammg colored composite particle suitable for incorporation in a bleach-contammg or non-bleach- contaming liquid detergent composition, a non-stainmg colored composite particle and a liquid dishwashing detergent composition. In one aspect of the present invention, the process includes the steps of forming a colored liquid dispersion of pigment particles in a first liquid medium. The size of the pigment particles in the colored liquid dispersion is no greater than about 5 μm. The process includes the step of mixing the colored liquid dispersion with a polymeric material and a second liquid medium to form a sprayable colored polymeπc mateπal. The polymeric mateπal being selected from the group consisting of alkyl cellulose ethers and polyvinyl alcohol. The process also includes the step of spraying the colored polymeπc material on a composite particle and forming a colored polymeπc coating on the composite particle. In another aspect of the present invention, a non-staining colored composite particle suitable for incorporation in a bleach-contammg liquid detergent composition is disclosed. The particle is made by the process as set forth above. In yet another aspect of the present invention, a liquid automatic dishwashing detergent product is disclosed. The product includes a liquid dishwashing detergent composition containing chloπne bleach, and non-staming colored composite particles. The particles are made by the process as set forth above. DETAILED DESCRIPTION OF THE INVENTION In the preferred embodiment of the present invention, the process includes the steps of forming a colored liquid dispersion of pigment particles in a first liquid medium. Pigment processing The size of the pigment particles in the colored liquid dispersion is desirably no greater than about 5 μm, preferably no greater than about 1 μm, more preferably no greater than about 0J μm, and most preferably no greater than about 0.01 μm. It has been surpπsmgly discovered that when the pigment particle size in the pigment-liquid dispersion is maintained withm the above size limitations, the resultant pigment, when deposited on a particle as a part of the sprayable polymeπc slurry, is essentially non-stammg. i.e., its color does not transfer onto plastic surfaces. The selection of the pigment particle size is the key to the present invention. One skilled m the art can apply other means for achieving a pigment particle size in the size limitation as disclosed above. In the preferred embodiment, the first liquid medium is preferably water. Optionally, a minor amount of a nomonic surfactant is added to the water to improve the dispersion of the pigment. Typically, this surfactant is added in an amount no greater than about 10% by weight. In the preferred embodiment, the process includes the step of maintaining the amount of surfactants used in the bleach-containing liquid detergent composition at a preselected value such that when the bleach-containing liquid detergent composition is diluted m a wash solution, the amount of surfactant delivered m the wash solution is less than cπtical micelle concentration The term "critical micelle concentration" is well known to those skilled m the art and need not be explained any further for purposes of brevity. Polvmenc coating In the preferred embodiment, the colored polymeπc coating is insoluble in the liquid automatic dishwashing detergent composition but soluble m automatic dishwashing wash solution. The coating is prepared from mateπals which are insoluble in the liquid automatic dishwashing detergent composition but soluble m automatic dishwashing wash solution. The coaling is prepared from mateπals selected from the group consisting of alkyl cellulose ethers and polyvmyl alcohol. Alternatively, the coating is prepared from algmate. Desirably, the alkyl cellulose ethers are selected from one of methyl cellulose and hydroxypropyl methyl cellulose (HPMC). Preferably, the coating is prepared from methyl cellulose having a number average molecular weight desirably in a range of from about 5000 to about 100,000, more preferably from about 10,000 to about 20,000, and most preferably, about 14,000. The preferred methyl cellulose IS one sold under the trade name Methocel A15LV. and manufactured by Dow Chemicals. Alternatively, the polymeric coating is polyvmyl alcohol (PVA) having a molecular weight, desirably m a range of from about 5000 to about 100,000, and preferably from about 13,000 to about 23,000 The preferred PVA is from about 87% to about 89% hydrolyzed, such as a commercially available product having a trade name Airvol 205. Further, the particles are insoluble in the liquid automatic dishwashing detergent composition and only soluble m the wash solution duπng automatic dishwashing. Process for spraying colored polymeπc coating on particles The process by which the colored polymeric coating is prepared and deposited upon the particle is critical in order for the particles to remain undissolved in the liquid automatic dishwashing detergent composition and only become soluble m the wash solution duπng automatic dishwashing. It is desirable that the particles dispersed m the liquid ADW compositions do not break up or dissolve in the composition. It is also desirable that this be achieved without depositing an unduly thick coating of a polymeric mateπal on the particle. It has been surprisingly discovered that when the polymeπc mateπal, such as methyl cellulose is sufficiently hydrated before spraying on the particle or prill, the polymer coated particle or prill remains stable, unbroken and undissolved in the liquid ADW composition. This hydration is achieved by forming a sprayable aqueous solution of the polymer (alkyl cellulose ether and/or polyvmyl alcohol) having a polymer concentration desirably in a range of from about 1% to about 30%) by weight, preferably in a range of about 3% to about 20 %, more preferably in a range of about 3% to about 10 %, and most preferably, about 5%. Further, the temperature of aqueous solution of the polymer is desirably maintained within a range of from about 30 °C to about 40 °C while spraying the polymer solution on the particle, and preferably m a range of from about 32 °C to about 38 °C, and most preferably at a temperature of about 35 °C. It has been surpπsingly found that by using a combination of the above process steps, i.e., the polymer solution being in a range of from about 1% to 30% by weight, and the spray temperature being m a range of from about 30 °C to about 40 °C, that a very stable, unbroken, continuous coating is formed on the particle or pπll which is undissolved in the liquid ADW composition but soluble m the wash solution, while at the same time, requiπng only about 5% polymer by weight of the particle. In the preferred embodiment, the coating is desirably present m an amount in a range of from about 1% to about 25% by weight of the particle, preferably from about 4% to about 10% by weight of the particle, and most preferably, about 5% by weight of the particle. The reduced coating weight levels are desirable so that the least effective coating amount is used in order to accomplish the objective to having a protective coating without unnecessary polymer that might detπmentally contribute to unwanted residue deposition in the washing machine. Color In one embodiment, the particles are colored and the automatic dishwashing liquid detergent composition is clear or translucent, so as to make the liquid automatic dishwashing product aesthetically pleasing. In another embodiment, the particles and the liquid automatic dishwashing detergent composition are both colored and the color of the particles is matched to the base color of the liquid composition. In one embodiment, the particles have a dark green color whereas the liquid composition has a light green color. Other preferred color combinations for the polymeπc coating on the particles and the liquid automatic dishwashing composition are: blue:blue, blue:whιte, gree green, greemwhite and green:yellow, respectively. Desirably, the particles comprise from about 0.1% to about 5.0% by weight of the liquid composition, and preferably, from about 0.2% to about 1.0% by weight of the liquid composition. In another embodiment of the present invention, a non-stammg colored composite particle suitable for incorporation in a bleach-contammg liquid detergent composition is disclosed. The particle is made by the process as set forth above. Particles The particles can be formed from vaπous mateπals that do not cause any detπmental affect upon the performance of the liquid detergent. Preferably, the particles are in the form of pπlls. The prills typically have a core which is coated with a polymeπc coating as descπbed before. The core can be made from sucrose, as an example. The method of forming pπlls is well known to those skilled m the art and is disclosed m the literature, such as for example, in U.S. Patent No. 4,965,012, which is incorporated herein by reference. The particles can be of vaπous sizes and shapes, such as spheπcal, oval, cyhndπcal or polygonal and desirably have a particle size in a range of from about 200 μm to about 5000 μm, preferably, from about 400 μm to about 2000 μm, and most preferably, from about 500 μm to about 850 μm. In yet another embodiment of the present invention, a liquid automatic dishwashing detergent product is disclosed. The product includes a liquid dishwashing detergent composition containing chlorine bleach, and non-stammg colored composite particles. The particles are made by the process as set forth above. Liquid automatic dishwashing composition components The liquid automatic dishwashing detergent product is highly viscous in a quiescent state and has a relatively high yield stress values. When subjected to shear stresses, however, such as being shaken m a container or squeezed through an orifice, the product quickly fluidizes and upon cessation of the applied shear stress, quickly reverts to a high viscosity state. The above liquid automatic dishwashing detergent product is preferably low foaming, readily soluble in the washing medium and most effective at pH values best conducive to improved cleaning performance, such as in a range of desirably from about pH 7.0 to about pH 13.0, and preferably from about pH 8.0 to about pH 12.0. The physical stability of the liquid product may be improved and the thickness of the liquid product may be altered by the addition of a cross linking polyacrylate thickener to the liquid detergent product as a thixotropic thickener. PH admstmg components The pH adjusting components are desirably selected from sodium or potassium carbonate or sesquicarbonate, sodium or potassium silicate, citπc acid, sodium or potassium bicarbonate, sodium or potassium borate, sodium or potassium hydroxide, and mixtures thereof. NaOH or KOH are the preferred ingredients for increasing the pH to withm the above ranges. Other preferred pH adjusting ingredients are sodium carbonate, potassium carbonate, and mixtures thereof. Low Foaming Surfactant Chloπne bleach stable low foaming surfactants are preferred and such surfactants are present in a range of from about 0.1% to about 10% by weight of the liquid composition. Such surfactants are generally known to one skilled m the art and need not be elaborated here, for purposes of brevity. One example of such a surfactant is an aniomc surfactant commercially available under the trade name Dowfax. Other ingredients The liquid automatic dishwashing detergent composition optionally also contains from about 0.5% to about 20% of a dispersant polymer selected from the group consisting of polyacrylates and polyacrylate copolymers, and from about 0.1% to about 5% of a chloπne bleach stable foam suppressant. Such foam suppressants are well known to those skilled in the art. To exemplify vaπous embodiments of the present invention, Sample A of the liquid automatic dishwashing detergent product composition is formulated using the below named ingredients, as set forth in Example A. EXAMPLE A Ingredient (weight % active) A Sodium Tπpolyphosphate 17.5 Potassium Tπpolyphosphate — Sodium Silicate 6.0 Potassium hydroxide 3.6 Sodium hydroxide 2.0 Polyacrylate polymer 1.0 Nitric Acid 0.012 Perfume 0.03 Nomonic surfactant — Sodium Benzoate 0.75 Sodium hypochloπte 1.15 Polyacrylate polymer thickener 1.5 Dye solution — Solid Pπll 0.5 Water Bal. TOTAL 100.0 In the above composition, the non-staining colored particles having a sphencal shape, and a diameter of about 750 μm, are formed from a sucrose core coated with a polymeπc coating formed from methyl cellulose (Methocel A15LV), and having a bluish-green color. The bluish- green color is imparted by adding a pigment into the methyl cellulose coating before spraying it on the particle according to the process of the present invention. The particles compπse about 0.1% to about 5% by weight of the liquid composition. The optimum methyl cellulose coating is about 5% by weight of the particle. The coating is sprayed on the sucrose core particle by spraying a 5% by weight aqueous solution of methyl cellulose with pigment. The aqueous solution temperature being carefully maintained at about 35 °C. The size of the pigment particles in the aqueous solution is no greater than about 1 μm. The resultant particles are insoluble in the liquid composition but are soluble m the wash solution duπng automatic dishwashing. The resultant colored particles are also non-stammg to plastic surfaces. Accordingly, having thus described the invention in detail, it will be obvious to those skilled in the art that vaπous changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is described in the specification.

Claims: WHAT IS CLAIMED IS: 1 A process for forming a non-stammg colored composite particle suitable for incorporation in a bleach-contammg liquid detergent composition, characterized by the steps of forming a colored liquid dispersion of pigment particles in a first liquid medium, wherein the size of said pigment particles in said colored liquid dispersion is no greater than 5 μm; mixing said colored liquid dispersion with a polymeπc mateπal and a second liquid medium to form a sprayable colored polymeπc mateπal, said polymeπc material being selected from the group consisting of alkyl cellulose ethers and polyvmyl alcohol; and spraying said colored polymeπc mateπal on a composite particle, and forming a colored polymeπc coating on said composite particle. 2. The process according to claim 1 , wherein the size of said pigment particles in said colored liquid dispersion is no greater than 1 μm. 3. The process according to any of claims 1-2, wherein the size of said pigment particles in said colored liquid dispersion is no greater than 0J μm. 4. The process according to any of claims 1-3, wherein the size of said pigment particles in said colored liquid dispersion is no greater than 0.01 μm. 5. The process according to any of claims 1 -4, wherein the first liquid medium is water 6. The process according to any of claims 1-5, wherein the first liquid medium is water mixed with up to about 10% by weight of a nomonic surfactant. 7 The process according to any of claims 1-6, further including the step of maintaining the amount of surfactants used in said bleach-contammg liquid detergent composition at a preselected value such that when the bleach-contammg liquid detergent composition is diluted in a wash solution, the amount of surfactant delivered in the wash solution is less than cπtical rnicell concentration. 8. The process according to any of claims 1-7, wherein said composite particle remains insoluble in said bleach-containing liquid detergent composition but soluble in automatic dishwashing wash solution. 9. The process according to any of claims 1-8, wherein said colored polymeπc coating is soluble in an automatic dishwashing wash solution and leaves no significant residue. 10. The process according to any of claims 1-9, wherein the step of spraying said colored polymeπc material on a composite particle includes the step of forming a sprayable aqueous solution of a polymeric mateπal, said polymeric mateπal being present in said sprayable aqueous solution in an amount in a range of from 1% to 20% by weight.

Inventors: FOLEY PETER ROBERT, LEYENDECKER MARY RUTH, PAINTER JEFFREY DONALD, SADLOWSKI EUGENE STEVEN, SONG XIAOQING, THIEN JOSEPH HERBERT, FOLEY, PETER, ROBERT, LEYENDECKER, MARY, RUTH, PAINTER, JEFFREY, DONALD, SADLOWSKI, EUGENE, STEVEN, SONG, XIAOQING, THIEN, JOSEPH, HERBERT
Applicants: FOLEY PETER ROBERT, LEYENDECKER MARY RUTH, PAINTER JEFFREY DONALD, PROCTER & GAMBLE, SADLOWSKI EUGENE STEVEN, SONG XIAOQING, THIEN JOSEPH HERBERT, FOLEY, PETER, ROBERT, LEYENDECKER, MARY, RUTH, PAINTER, JEFFREY, DONALD, SADLOWSKI, EUGENE, STEVEN, SONG, XIAOQING, THE PROCTER & GAMBLE COMPANY, THIEN, JOSEPH, HERBERT
Application year: 2000
Main classification: C11D17
IPC codes: C09B63, C09B67, C11D3, C11D7, C11D11, C11D17