Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-06-29
2004-01-06
Hardee, John (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S514000
Reexamination Certificate
active
06673760
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a rinse agent composition and to a method for rinsing a substrate surface. The composition and method are particularly useful with high solids containing water. The rinse agent composition includes a sheeting agent and a sufficient amount of a humectant for controlling the appearance of water solids on articles including cookware, dishware, flatware, glasses, cups, motor vehicle exteriors, hard surfaces, glass surfaces, etc.
BACKGROUND OF THE INVENTION
Mechanical warewashing machines have been common in the institutional and household environments for many years. Such automatic warewashing machines clean dishes using two or more cycles which can include initially a wash cycle followed by a rinse cycle. Such automatic warewashing machines can also utilize soak cycle, pre-wash cycle, scrape cycle, second wash cycle, rinse cycle, a sanitizing cycle, and drying cycle. Any of these cycles can be repeated, if desired, and additional cycles can be used. Rinse agents are conventionally used in warewashing applications to promote drying and to prevent the formation of spots. Even when both goals are accomplished, water solids filming is often evident. After a wash, rinse, and dry cycle, dishware, cups, glasses, etc., can exhibit filming that arises from the dissolved mineral salts common to all water supplies. Water solids filming is aesthetically unacceptable in most consumer and institutional environments.
Water solids filming on cookware, dishware and flatware is a particular problem in the presence of high solids containing water. In general, rinse waters containing in excess of 200 ppm total dissolved solids (TDS) tends to leave a visible film on glass and flatware after they are dried. Above 400 ppm, the films become objectionable, and above 800 ppm, the films are particularly aesthetically unacceptable. The TDS content can be reduced by a demineralization process, such as reverse osmosis, which can be expensive.
In order to reduce the formation of spotting, rinse agents have commonly been added to water to form an aqueous rinse that is sprayed on the dishware after cleaning is complete. The precise mechanism through which rinse agents work is not established. One theory holds that the surfactant in the rinse agent is absorbed on the surface at temperatures at or above its cloud point, and thereby reduces the solid-liquid interfacial energy and contact angle. This leads to the formation of a continuous sheet which drains evenly from the surface and minimizes the formation of spots. Generally, high foaming surfactants have cloud points above the temperature of the rinse water, and, according to this theory, would not promote sheet formation, thereby resulting in spots. Moreover, high foaming materials are known to interfere with the operation of warewashing machines. Common rinse aid formulations used in warewashing machines are used in an amount of less than about 1,000 parts, commonly 10 to 200 parts per million of active materials in the aqueous rinse. Rinse agents available in the consumer and institutional markets include liquid or solid forms that are typically added to, dispersed or dissolved in water to form an aqueous rinse. Such dissolution can occur from a rinse agent installed onto the dish rack. The rinse agent can be diluted and dispensed from a dispenser mounted on or in the machine or from a separate dispenser that is mounted separately but cooperatively with the dish machine.
Many commercial rinse agents include polyalkylene oxide copolymers and ethylene oxide/propylene oxide block copolymers. In such materials, the ethylene oxide block tends to be hydrophilic while the propylene oxide blocks tend to be hydrophobic producing a separation of hydrophilic and hydrophobic groups on the surfactant molecule. Surfactants can be formed by reacting an alcohol, a glycol, a carboxylic acid, an amine or a substituted phenol with various proportions and combinations of ethylene oxide and propylene oxide to form both random and block copolymers.
Exemplary rinse agent compositions are described by U.S. Pat. No. 5,589,099 to Baum; U.S. Pat. No. 5,447,648 to Steindorf; U.S. Pat. No. 5,739,099 to Welch et al.; U.S. Pat. No. 5,712,244 to Addison et al.; U.S. Pat. No. 5,545,352 to Pike; U.S. Pat. No. 5,273,677 to Arif; and U.S. Pat. No. 5,516,452 to Welch et al.
SUMMARY OF THE INVENTION
A rinse agent composition is provided according to the invention. The rinse agent composition includes a sheeting agent for promoting draining of sheets of water from a surface, and a humectant. The weight ratio of the humectant to the sheeting agent is preferably greater than about 1:3 and more preferably between about 5:1 and about 1:3.
Sheeting agents which can be used according to the invention include surfactants which provide a sheeting effect on a substrate and which, when used with the humectant, provide reduced water solids filming in the presence of high solids containing water compared with a composition not containing the humectant. That is, the sheeting agent promotes draining of sheets of water from a surface to promote drying. Exemplary sheeting agents which can be used in the rinse agent composition according to the invention include nonionic block copolymers having ethylene oxide and propylene oxide residues, alcohol alkoxylates, alkyl polyglycosides, zwitterionics, anionics, and mixtures thereof.
Humectants that can be used according to the invention include those materials that contain greater than 5 wt. percent water when the humectant is equilibrated at 50% relative humidity and room temperature. Exemplary humectants that can be used according to the invention include glycerine, propylene glycol, sorbitol, alkyl polyglycosides, polybetaine polysiloxanes, and mixtures thereof. It is understood that certain sheeting agents may fit the definition of a humectant according to the invention. Similarly, certain humectants may be considered sheeting agents. For purposes of determining the weight ratio of humectant to sheeting agent, it should be understood that the humectant and the sheeting agent for a particular rinse agent composition are different.
A method for rinsing a substrate surface in the presence of high solids containing water is provided according to the invention. The method includes a step of applying an aqueous rinse agent composition to a substrate surface. The rinse agent composition according to the invention is particularly useful for reducing the appearance of water solids filming caused by rinse waters containing in excess of 200 ppm total dissolved solids. The method preferably includes a step of cleaning the substrate surface prior to the step of rinsing.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to a rinse agent composition that includes a sheeting agent and a humectant. The sheeting agent is provided in an amount sufficient to improve the sheeting properties of the rinse agent composition. Sheeting properties refer to the ability of the rinse agent composition to form a continuous film or sheet on a substrate which promotes a continuous, even draining film of water and which leaves virtually no spots upon evaporation of the remaining water. In general, the presence of an unacceptable amount of spots on a substrate surface reflects the presence of an insufficient amount of sheeting agent according to the invention. The humectant is provided in an amount sufficient to reduce the visibility of a film on the substrate surface. The visibility of a film on substrate surface is a particular concern when the rinse water contains in excess of 200 ppm total dissolved solids. Accordingly, the humectant is provided in an amount sufficient to reduce the visibility of a film on a substrate surface when the rinse water contains in excess of 200 ppm total dissolved solids compared to a rinse agent composition not containing the humectant. The terms “water solids filming” or “filming” refer to the presence of a visible, continuous layer of matter on a substrate surface that gives the appearance that the substrate
Killeen Yvonne M.
Lentsch Steven E.
Man Victor F.
Ecolab Inc.
Hardee John
Merchant & Gould P.C.
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