FIELD OF INVENTION

The present invention relates to solid rinse aid compositions, and methods for manufacturing and using the same. The rinse aid compositions generally include a novel solidification system and surfactants which may include a sheeting agent, a defoaming agent, and an association disruption agent. The rinse aids can be used in aqueous use solutions on articles including, for example, cookware, dishware, flatware, glasses, cups, hard surfaces, glass surfaces, vehicle surfaces, etc. The rinse aids can also be used as wetting agents for use in aseptic filling procedures.

BACKGROUND

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, but may also utilize soak, pre-wash, scrape, sanitizing, drying, and additional wash cycles. Rinse agents are conventionally used in warewashing applications to promote drying and to prevent the formation of spots.

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.

A number of rinse aids are currently known, each having certain advantages and disadvantages. There is an ongoing need for alternative rinse aid compositions, especially alternative rinse aid compositions that are environmentally friendly (e.g., biodegradable), and that essentially include components that are suitable for use in food service industries, e.g. GRAS ingredients (generally recognized as safe by the USFDA, partial listing available at 21 C.F.R. §§ 184).

SUMMARY OF THE INVENTION

Applicants have surprisingly found that the short-chain alkylbenzene and alkyl naphthalene sulfonates class of hydrotopes which are traditionally included at low concentrations in detergents and rinse aids, when included at higher percentages, can act as a solidification aid. This class typically includes sodium xylene sulfonate, sodium toluene sulfonate, sodium cumene sulfonate, potassium toluene sulfonate, ammonium xylene sulfonate, calcium xylene sulfonate, sodium alkyl naphthalene sulfonate, and/or sodium butylnaphthalene.

A solid rinse agent composition of the present invention thus includes a solidification system including a short chain alkyl benzene and/or alkyl naphthalene sulfonate, preferably sodium xylene sulfonate (SXS), and a surfactant system. The surfactant can include a sheeting agent of one or more alcohol ethoxylates. The solid rinse aid composition may advantageously be formulated to phosphate-free and aminocarboxylate-free, as well as containing only ingredients generally recognized as safe (GRAS) for human consumption.

In at least some embodiments, the solid rinse aid includes a surfactant system with a sheeting agent component comprising one or more alcohol ethoxylates that include an alkyl group that includes 12 or fewer carbon atoms and is a solid at room temperature. For example, in some embodiments, the rinse aid can include a sheeting agent component including one or more alcohol ethoxylates having the general formula:
R—O—(CH2CH2O)n—H
wherein R is a (C1-C12) alkyl group, and n is an integer in the range of 1 to 100.

The rinse aid surfactant system can also include an effective amount of defoamer component configured for reducing the stability of foam that may be created by the alcohol ethoxylate in an aqueous solution. In other embodiments, the defoaming agent comprises a polymer compound including one or more ethylene oxide groups. In yet other embodiments, the defoaming agent includes a polyether compound prepared from ethylene oxide, propylene oxide, or a mixture thereof. In still yet other embodiments, the defoaming agent comprises a polyoxypropylene-polyoxyethylene block copolymer surfactant.

In some embodiments, the solid rinse aid surfactant system includes one or more association disruption agent comprising an alcohol alkoxylate. In other embodiments, the association disruption agent is selected from the group consisting of ethylene oxides, propylene oxides, butylene oxides, pentylene oxides, hexylene oxides, heptylene oxides, octylene oxides, nonylene oxides, decylene oxides, and mixtures and derivatives thereof.

Some embodiments of the inventive solid rinse aid composition also include a GRAS preservative system for acidification of the solid rinse aid including sodium bisulfate and organic acids. The use solution can be neutral or acidic. In at least some embodiments, a use solution of the solid rinse aid has a pH that is less than pH 4, and often less than pH 2.

Some example methods, including heating and vigorous mixing are described for processing the rinse aid compositions, generally include the steps of combining the sodium xylene sulfonate and sheeting component, as well as any topional defoamer, disruption aid, and, if desired, any other suitable additives so as to produce the rinse aid. These steps are followed by casting, extruding, or the like to form solid product or simply by pressing to form a pressed solid. The rinse aid can be provided as a concentrate or as a use solution. The rinse aid concentrate is typically provided in a solid form. In general, it is expected that the concentrate will be diluted with water to provide the use solution that is then supplied to the surface of a substrate. The use solution preferably contains an effective amount of active material to provide reduced water solids filming in rinse water. It should be appreciated that the term “active materials” refers to the nonaqueous portion of the use solution that functions to reduce spotting and water solids filming.

Some example methods for using the rinse aid generally include the step of providing the rinse aid, mixing the rinse aid into an aqueous use solution, and applying the aqueous use solution to a substrate surface.

In some embodiments, the hardening agent of a short chain alkyl benzene or alkyl naphthalene sulfonate is present 60 wt % to 90 wt % and the surfactant package is present at 5 wt % to 35 wt %. The solid rinse aid can also in some embodiments and as enumerated hereinafter, include an additional solidification component such as polyethylene glycol or urea. The additional solidification agent is used is present in an amount for from about 0.1 wt % to about 10 wt %.

The surfactant package can comprise a sheeting agent present at about 1 wt % to about 10 wt %. In other embodiments, the sheeting agent is present at about 2 wt % to about 5 wt %. In still yet other embodiments, the defoaming agent is present at about 1 wt % to about 20 wt %. In still yet other embodiments, the surfactant system includes a defoaming agent present at about 1 wt % to about 15 wt %. In some embodiments, the surfactant system with one or more association disruption agent is present at between about 1 wt % to about 25 wt %. In other embodiments, the one or more disruption agent is present at between about 10 wt % to about 20 wt %.

In some embodiments, the surfactant package includes a ratio of sheeting agent to defoaming agent to association disrupting agent in the surfactant package is about 1.0:1.5:30 to about 1:2:1. In other embodiments, the association disruption agent is present at an amount effective to reduce the contact angle of the composition by between about 5° to about 15°. In still yet other embodiments, the additional ingredient comprises at least about 50 wt % of a carrier. In other embodiments, the carrier comprises water.

In some aspects, the present invention is related to methods for rinsing ware in a warewashing application. The methods comprise providing an aqueous rinse aid composition, the rinse aid composition consisting essentially of: a sheeting agent, a defoaming agent, one or more of an association disruption agent; a hardening agent of short chain alkyl benzene or alkyl naphthalene sulfonate and an if desired, any additional ingredients such as a carrier, a hydrotrope, a chelating/sequestering agent, and combinations thereof. The method also comprises diluting the rinse aid composition with water to form an aqueous use solution; and applying the aqueous use solution to the ware.

In some embodiments, the ware comprises plasticware. In other embodiments, the ware dries within about 30 to about 90 seconds after the aqueous solution is applied to the ware.

