DE68912938T2 - AT LOW TEMPERATURE POURED ITEM CONTAINING DETERGENT. - Google Patents

Description

This invention relates to a novel solid cast detergent-containing article which is particularly useful at low water temperatures in institutional dishwashers and industrial washing machines. Another aspect of this invention relates to a method of making the detergent-containing article. Another aspect of this invention relates to a method of using the detergent-containing article.

Solid cast heavy-duty detergent-containing articles that can be used in institutional dishwashers and industrial washing machines at high water temperatures are known in the art. The advent of such heavy-duty products has been stimulated in part by increased aesthetic and hygienic standards and a demand for shorter wash times. Such heavy-duty products are generally complex detergent compositions that are hazardous to the user. Solid heavy-duty detergents have generally a high alkalinity (e.g. higher concentrations of sodium hydroxide) which exceeds the point at which it creates a safety hazard for the user.

Solid cast heavy-duty detergent compositions for use at high temperatures typically contain high concentrations of alkali metal hydroxides. In addition to alkali metal hydroxides (e.g., sodium hydroxide), chemicals used in high temperature, heavy-duty products, particularly for cleaning hard surfaces (e.g., dishwashing), include phosphates, silicates, chlorine-containing compounds, defoamers, and organic polyelectrolyte polymers. See U.S. Patent No. 3,166,513, issued January 19, 1965 (Mizuno et al.); U.S. Patent No. 3,535,258, issued October 20, 1970 (Sabatelli et al.); U.S. Patent No. 3,579,455, issued May 18, 1971 (Sabatelli et al.); U.S. Patent No. 3,700,599, issued October 24, 1972 (Mizuno et al.) and U.S. Patent No. 3,899,436, issued August 12, 1975 (Copeland et al.). The alkali metal hydroxides in these compositions are very effective in removing most stubborn food stains, but a source of available chlorine is usually included to control food stains such as tea and coffee stains. The defoamer is usually included to control the foam formed by proteinaceous soils and saponified fats. The use of chlorinated cyanurates as a source of available chlorine in detergents used to clean hard surfaces is disclosed in U.S. Patent No. 3,166,513, issued January 19, 1965 (Mizuno et al.); U.S. Patent No. 3,933,670, issued January 20, 1976 (Brill et al.); and U.S. Patent No. 3,936,386, issued February 3, 1976 (Corliss et al.).

In addition to their high alkalinity, which poses a hazard to users, another problem with these solid cast heavy-duty detergent-containing articles for use at high temperatures is their reduced effectiveness at low water temperatures. While the prior art high alkali compositions are effective at high water temperatures, they typically exhibit reduced effectiveness at water temperatures below about 140ºF (60ºC), requiring the use of a large amount of detergent composition to obtain satisfactory cleaning results.

At high water temperatures, sodium hydroxide will effectively dissolve proteins and saponify fats. At low water temperatures, however, the cleaning power of sodium hydroxide may be reduced depending on the degree and type of contamination.

There is therefore a need for a solid cast detergent composition that is effective at water temperatures below approximately 140ºF (60ºC), minimizes hazards to users, and does not require large amounts of product to be used.

It has now been found that the above-described safety problems associated with high alkalinity and cold water effectiveness problems can be minimized by forming a solid cast detergent in a disposable mold and dispensing or using the detergent directly from the mold/cast detergent combination, wherein the cast detergent composition comprises an alkali metal hydroxide, 5 to 12.6% by weight of a nonionic surfactant, a water softener and water of hydration. The combination of the cast detergent composition and the disposable mold in which it was formed provides a commercial article capable of releasing dissolved solids from substantially only one side of the surface which was the free or uncontained surface in the mold. Alternatively, the solid cast detergent composition can be removed from the mold in which it was formed prior to use.

The present invention thus relates to a solid cast three-dimensional low temperature detergent composition comprising an alkali metal hydroxide, 5 to 12.6% by weight of a non-ionic surfactant, a water softener and water of hydration. The invention may further comprise a container-shaped mold containing the detergent composition and surrounding it on all sides except one.

The detergent composition is normally formed by mixing and heating the components in an aqueous solution, thickening the solution, pouring the solution into the mold and preferably also cooling the solution and allowing the mixture to harden, it being understood that hardening may involve one or more physico-chemical mechanisms including "freezing", precipitation from solution, hydration, etc. Preformed plugs or cores of a chlorine source and/or a defoaming agent may be introduced into the mixture after it has been placed in a mold and before it has hardened.

The solid detergent composition is preferably used in the disposable mold in which it was cast. Alternatively, the cast detergent may be removed from the mold and placed in an inexpensive container having substantially the same shape as the mold, since in both cases the cast detergent is enclosed on all but one side as previously described. The cast detergent thus enclosed is used by placing its exposed surface in a leachable position (preferably fixed) within a detergent dispenser. A fixed leachable position is a position in which the aforementioned unenclosed exposed surface is fixed with respect to the horizontal and a potentially impinging liquid spray such that gravity flow is permitted from the unenclosed exposed surface either by gradual inclination with respect to the horizontal (e.g. by 10º to 90º) or by inclination beyond 90º, i.e. partial or complete inversion up to and including a fully inverted or downward position. A liquid spray impinging on the leachable (inclined or inverted) surface and suitably controlled as to its duration results in a leaching or gravity flow of liquid detergent which flows downward from the leachable surface to the washing machine into which the detergent is to be dispensed. Controlling the duration of the impact (i.e. the duration of the downward flow) has the effect of controlling the detergent concentration in the washing machine. The dispenser is not a water-in-reservoir type because it dispenses the flow of liquid detergent at approximately the same rate as that flow is created by the spraying action.

A component required for the preparation of the solid cast low temperature detergent compositions of the present invention is an alkali metal hydroxide. Suitable alkali metal hydroxides include, but are not limited to, sodium hydroxide and potassium hydroxide. For economic reasons, the solid cast low temperature detergent composition preferably comprises sodium hydroxide.

The alkali metal hydroxide comprises 10 to 60 wt.% of the detergent composition for chemical soil removal, preferably 20 to 50 wt.% for more cost-effective soil removal, and most preferably 35 to 50 wt.% for most cost-effective soil removal. If the alkali metal hydroxide concentration is too low, soil removal performance will deteriorate. If the alkali metal hydroxide concentration is too high, an increase in usage cost will result.

The alkali metal hydroxide is used in the solid cast low temperature detergent composition for chemical soil removal.

A second required component of the solid cast low temperature composition of this invention is water. Water is used in conjunction with alkali metal hydroxide to form a fusible carrier medium containing the detergent components, which medium is poured into a mold and cured by a curing mechanism previously described. Water may be used as a single ingredient or in conjunction with one of the other components, e.g., as an aqueous 50% sodium hydroxide solution. be added.

The water of hydration will comprise from 5 to 30 weight percent, preferably from 10 to 20 weight percent to maintain the mixture liquid and workable at a temperature between about 155 to 180°F (68.3 to 82.2°C), and most preferably from 12 to 15 weight percent of the detergent composition to maintain the mixture liquid and workable at a temperature between about 155 to 180°F (68.3 to 82.2°C).

A third required component of the solid cast low temperature detergent composition of this invention is a nonionic surfactant. It has been found that the cleaning power of the alkali metal hydroxide may be reduced at low water temperatures depending on the amount and type of soil. To obtain the desired cleaning results at low temperatures, a nonionic surfactant is added to enhance the cleaning action of the alkali metal hydroxide. The nonionic surfactant serves to emulsify rather than saponify the fats. The nonionic surfactant used must be compatible with the alkali metal hydroxide and low foaming. Useful nonionic surfactants include, but are not limited to, ethoxylated long chain alcohols terminated with a benzyl group. The general formula is R-(OC₂H₄)nCH₂-benzyl radical. n is an integer and is between 6 to 30. R is an alcohol and can be a straight chain saturated or unsaturated alcohol or a mixture of alcohols such as decyl alcohol, dodecyl alcohol, tetradecyl alcohol, cetyl alcohol, oleyl alcohol, linoleyl alcohol, palmitoleyl alcohol, arachidyl alcohol, stearyl alcohol, behenyl alcohol, arachidonyl alcohol, myristoleyl alcohol and the like. Additional nonionic surfactants that can be used in the solid cast low temperature detergent compositions of the present invention include, but are not limited to, ethylene oxide-propylene oxide block copolymers such as Triton CF54 available from Rohm & Haas, Plurafac RA-U3 available from Wyandotte, Pluronic L62 available from Wyandotte, Triton CF 10 available from Rohm & Haas and Pluronic R61 available from Wyandotte.

The non-ionic surfactant is contained in the solid cast detergent composition itself rather than in a plug or core for reasons of convenience and ease of manufacture.

The solid cast low temperature detergent composition for washing goods of the present invention should comprise, for emulsification of fatty soils, from 5 to 12.6% by weight, preferably, for more effective emulsification of fatty soils, from about 5 to 9% by weight, and most preferably, for optimal emulsification of fatty soils, from about 4 to 8% by weight, of a non-ionic surfactant.

The detergent composition must contain a sufficient amount of non-ionic surfactant so that the detergent composition is effective at low water temperatures, i.e., at water temperatures ranging from about 100 to 160ºF (37.8 to 71.1ºC), preferably, for cost-performance reasons, from 120 to 140ºF (48.9 to 60ºC).

The non-ionic surfactant must be present in such a added to exceptionally high levels to achieve effective performance at low water temperatures.

A fourth required component of the solid cast low temperature laundry detergent composition is a chelating agent. The solid cast low temperature laundry detergent composition of the present invention should comprise from 10 to 50% by weight, preferably from about 15 to 34% by weight for reasons of profitability and legal restrictions, and most preferably from about 20 to 30% by weight for reasons of optimum profitability.

The process water usually used in cleaning baths contains considerable amounts of alkaline earth ions, mostly calcium and magnesium ions, which can react with detergent components, thereby reducing the effectiveness of the cleaning and/or leaving unsightly deposits on the cleaned substrate. Complexing agents prevent or delay the crystal growth of calcium or magnesium compounds and thus prevent them from reacting with other components and/or precipitating.

Suitable chelating agents for use in the solid cast low temperature detergent compositions of the present invention include, but are not limited to, phosphates, particularly phosphates of the formula M-(PO3M)nOM, where M is an alkali metal and n is a number between 1 to about 60, typically less than 3 for cyclic phosphates, typical examples of such phosphates being sodium or potassium orthophosphates and alkaline condensed phosphates (i.e., polyphosphates) such as sodium or potassium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, etc.

For reasons of complex formation, peptization and soil suspension, the complexing agent preferably comprises sodium tripolyphosphate.

For cost reasons, the complexing agent is preferably used in its anhydrous form. However, a complexing agent could also be used in its hydrated form if the water content of the other starting materials is adjusted downwards to compensate for the amount of water of hydration contained in the complexing agent.

In addition to these components described above, other common detergent components and fillers may be included. For example, it is possible to include a defoaming agent.

In addition to the nonionic surfactants mentioned above, defoamers may also be included in the solid cast low temperature detergent compositions. Defoamers will normally be included in the solid cast low temperature detergent composition in small amounts, i.e., about 0.1 to 5% by weight for profitability, preferably about 0.1 to 2.0% by weight for increased profitability, and most preferably about 0.2 to 0.5% by weight for optimum profitability. A "defoamer" is typically a chemical compound with a hydrophobic/hydrophilic balance suitable for reducing the stability of protein foam. The hydrophobicity may be provided by a lipophilic region of the molecule (e.g., an aromatic, alkyl or aralkyl group; an oxypropylene unit or chain or other oxyalkylene functional groups other than oxyethylene groups, e.g. tetramethylene oxide). Hydrophilicity can be created with oxyethylene units or chains or blocks and/or ester groups (e.g. organophosphate esters), salt-like groups or salt-forming groups. Typically, defoamers are nonionic organic surface-active polymers with hydrophobic groups or blocks or chains and hydrophilic ester groups, blocks, units or chains, but anionic, cationic and amphoteric defoamers are also known. For a disclosure of nonionic surfactant defoamers, see U.S. Patent No. 3,048,548, issued August 7, 1962 (Martin et al.), U.S. Patent No. 3,334,147, issued August 1, 1967 (Brunelle et al.), and U.S. Patent No. 3,444,242, issued May 13, 1969 (Rue et al.). Also suitable are phosphate esters, e.g., esters of the formula RO-(PO₃M)-nR, wherein n is as previously defined and R is an organic group or M (as previously defined), at least R being an organic group such as an oxyalkylene chain.

Optionally, the solid cast low temperature detergent composition may further comprise about 1 to 20 wt.% of hydratable crystalline alkali metal silicate for soil suspension and imparting alkalinity and corrosion protection, preferably about 10 to 20 wt.% for improved soil suspension and imparting additional alkalinity and corrosion protection, and most preferably about 12 to 18 wt.% for optimal soil suspension and imparting additional alkalinity and corrosion protection.

Alkali metal silicates are the reaction products of an alkali metal oxide (M2O) with silicon dioxide (SiO2) and have the general chemical formula (M2O)x:(SiO2)y, where x and y indicate the molar ratio of alkali metal oxide to silicon dioxide.

Methods for preparing alkali metal silicates having various x:y molar ratios are well known, as shown by the general presentation in Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, Volume 18, pages 139 - 141. The desired properties and advantages of the solid cast low temperature detergent composition described herein can be achieved by using an alkali metal silicate having an x:y ratio of approximately 1:1 to 3:1, preferably 1:1. At these ratios, the alkali metal silicate has sufficient alkaline character to effectively clean and sufficient silica to protect aluminum, china, glassware, etc. from the corrosive action of the basic components in the composition. These silicates also have excellent setting properties.

Due to high cleaning performance, excellent product protection and low cost, sodium metasilicate with a Na₂O:SiO₂ ratio of approximately 1:1 is the most preferred alkali metal silicate. Preferably, anhydrous alkali metal silicate is used to minimize the water content in the final product and to optimize the cost of use by concentrating the product.

Optionally, the solid cast low temperature detergent composition may further comprise a carbonate such as sodium carbonate and potassium carbonate. Carbonates may have a water content of approximately 0 to 30 % by weight, for reasons of cost optimization preferably about 15 to 25 wt. % and for optimal cost optimization mostly preferably about 15 to 20 wt. % of the detergent composition.

Carbonates serve the following function in the solid cast low temperature detergent composition of the present invention. They store water and harden the product in its container. Optionally, the solid cast low temperature detergent composition may further comprise a colorant. Colorants may comprise about 0.0 to 0.2% by weight, preferably about 0.0 to 0.1% by weight for cost and desired color, and most preferably about 0.005 to 0.05% by weight of the detergent composition.

Optionally, the solid cast low temperature detergent composition may further comprise about 0 to 5% by weight of a salt such as sodium chloride and/or sodium sulfate as a filler. Typically, a four-component composition of the solid cast low temperature detergent composition of the present invention may be formulated from (1) at least about 4% of a low foaming nonionic surfactant, (2) a phosphate or other alkaline earth ion precipitating agent or water softener, (3) an alkali metal hydroxide, and (4) water. Typically, five or six component compositions would further contain a defoaming agent and/or a neutral inorganic salt (alkali metal halides, sulfates, etc.) and/or a thickening agent, thixotropic agent, suspending agent or organic chelating or complexing agent or the like.

Typically, in the solid cast low temperature detergent composition of this invention, a condensed alkali metal phosphate is used for complexing alkaline earth ions (Mg++ and Ca++ ions). However, as an alternative to or in conjunction with the condensed phosphates, organic chelating or complexing agents (citric acid, polyelectrolytes such as the 1000 to 3000 molecular weight polyacrylates, etc.) have also been used; see, for example, U.S. Pat. No. 5,447,444. See, for example, U.S. Patent No. 3,535,285, issued October 20, 1970 (Sabatelli et al.), U.S. Patent No. 3,579,455, issued May 18, 1971 (Sabatelli et al.), U.S. Patent No. 3,700,599, issued October 24, 1972 (Mizuno et al.), and U.S. Patent No. 3,899,436, issued August 12, 1975 (Copeland et al.). As is known, polyacrylates (especially alkali metal salts of polyacrylic acid and their copolymers) can function as thickeners in aqueous systems. Cast detergent compositions according to the invention can optionally contain about 0 to 10 wt.%, preferably about 2 to 7 wt.% for reasons of viscosity, processing and profitability, and most preferably about 3 to 5 wt.% for reasons of optimum viscosity, processing and profitability, of polyelectrolytes in combination with condensed alkali metal phosphates.

Preferably, sodium polyacrylate is used as an organic complexing agent for viscosity control in the water softening process. Sodium polyacrylate helps prevent precipitation of a phosphate softener during the process.

The article according to the invention may also comprise a disposable package or mold into which the detergent composition is poured or cured. During shipping, the Articles typically include a lid or cover. The lid or cover may be made of the same or similar material used to make the mold. As will be explained below, this material is usually alkali resistant, unbreakable, and inexpensive. Expensive corrosion resistant metals or plastics may be used if provision can be made for their recycling, but "throw-away" materials would normally be preferred for most institutional applications. The solid cast low temperature detergent composition is typically surrounded by and in contact with the mold on all sides except the top of the solid cast detergent. A cross-section of the solid cast detergent may be more than 1 cm thick (e.g., 2 to 20 cm thick). The area of the top surface may easily exceed 100 cm2, e.g., 125 cm2 to 1000 cm2 or more. It has been discovered that, unlike compressed detergent tablets, cast detergent blocks can be made very large - in almost any desired size.

The mold or package can be made of any alkali-resistant material that can withstand moderately elevated temperatures, e.g., 150ºF (65.6ºC), and that can be molded into and retained in the desired shape. Since the mold is generally intended to be "disposable" (i.e., not intended for reuse as a mold), inexpensive materials such as thermoplastics, resin-impregnated heavy paper or cardboard, and the like are preferred. Inexpensive but fragile materials such as glass or ceramic are less preferred due to handling or transportation problems, and relatively flexible materials are preferred. Molds made of plastic (e.g. inexpensive thermoplastics) have proven to be particularly useful.

The article containing solid cast low temperature detergent can be used in conjunction with a detergent dispenser which can be part of a conventional institutional or industrial washing machine. The article comprising the detergent base and the packaging is placed in a fully downward facing or fully inverted position over a sprayer connected to a water source, whereby the exposed detergent surface becomes a leachable surface. When the water source is opened, the sprayer causes water to impinge on the exposed detergent surface. The detergent goes into solution, creating a stream of liquid, aqueous detergent which flows by gravity downward through a conduit to a wash tank or wash area of the washing machine. The detergent composition can be formulated to go into solution at a substantially uniform rate, thus delivering a consistent ratio of ingredients to the tank.

By controlling the spray time, the amount of detergent and thus the detergent concentration in the laundry can be controlled. In other words, the liquid, aqueous detergent formed as a result of the spray jet hitting the exposed detergent surface generally flows into the line by gravity at the same time as it is formed within a dispenser. The accumulation of standing water or aqueous liquid within the dispenser is not permitted.

The solid cast low temperature detergent composition of the present invention can be formed by a number of processes including, but not limited to, batch and semi-continuous processes.

Although the following processes are described with reference to specific components, it is to be understood that other components and similar processes can be used to form a detergent solution which can be poured into a mold and which will harden by hydration of its hydratable components to form a solid cast low temperature detergent composition. The solid cast low temperature detergent composition of this invention can be prepared by combining the components in a suitable mixer which is sufficiently resistant to chemical attack by the ingredients and has sufficient mixing capacity. Although the ingredients can generally be mixed together in any order without significantly degrading properties, the preferred method of preparing the composition is to first charge a large industrial scale mixer with an aqueous solution of an alkali metal hydroxide. Mixing and heating the aqueous alkali metal hydroxide solution results in a miscible liquid matrix. The remaining components can then be added to the solution in the industrial mixer. If the complexing agent used contains phosphate, it is preferably added towards the end of the process to minimize phosphate reversion.

The industrial mixer will operate at a sufficient speed and driving force and a sufficient temperature range to ensure adequate mixing of the components. Once the components are fully mixed and uniform, the composition is drawn off into molds or capsules for curing.

During processing, the components are preferably mixed and drawn into the capsule or mold to keep the product molten and thus workable while maintaining the temperature of the composition at about 150 to 160ºF (65.6 to 71.7ºC), preferably about 153 to 157ºF (67.2 to 69.4ºC) for optimum workability. The process must be run at a minimum of about 150ºF (65.6ºC) at all times to maintain a molten product.

A particularly useful detergent composition of this invention is formed by heating about 60 to 70 parts by weight of a 40 to 75 weight percent aqueous solution of an alkali metal hydroxide, e.g., sodium hydroxide, to a temperature of about 150 to 165°F (65.6 to 73.9°C), preferably, for optimum processing, about 154 to 157°F (67.8 to 69.4°C). See Examples 1 to 4, which follow. This temperature range is critical to the viscosity and quality of the final product, as it allows for mixing of the product while it is in its liquid state. Heating should then be discontinued after the temperature reaches the range specified above.

The alkali metal hydroxide solution is then agitated at a sufficient rate for effective heat distribution and to keep the solution mixed and flowing. Although other alkali metal hydroxides can be used, Sodium hydroxide has been found to be particularly useful and the following method of preparation will be described with reference to sodium hydroxide. 50 wt% aqueous sodium hydroxide solutions are readily available commercially. Solutions containing more than 50 wt% sodium hydroxide are also available (e.g. 73%) or can be prepared by adding a desired amount of anhydrous sodium hydroxide to a 50 wt% sodium hydroxide solution. An aqueous sodium hydroxide solution can also be prepared by mixing water and anhydrous sodium hydroxide in the desired ratio.

Then 0 to 4 wt%, preferably about 2 to 3 wt%, of water should be added to the mixing tank. The aqueous alkali metal hydroxide solution provides an aqueous carrier matrix in which all other components of the cast composition can be suspended or dissolved.

About 2 to 5 weight percent of a thickening agent, such as a low molecular weight polyacrylic acid, may be added to the mix tank while continuing mixing and maintaining the temperature of the mix tank contents between about 150 and 160ºF (65.6 and 71.1ºC).

The thickener typically comprises about 45 to 55 wt% water based on the thickener composition. If the thickener does not comprise water, the water content of the other components should be adjusted accordingly.

The addition of the thickener to the aqueous alkali metal hydroxide solution results in a mixture in which the alkali metal hydroxide hydrated and the polyacrylate thickener is used to maintain viscosity.

Then, to form the proper matrix, approximately 30 to 40 wt.%, preferably 35 to 40 wt.%, and most preferably approximately 34 to 36 wt.%, of anhydrous sodium hydroxide beads are added to the mixing tank. The addition of the anhydrous sodium hydroxide beads increases the concentration of sodium hydroxide in the mixture to its final value. With the addition of the anhydrous sodium hydroxide beads, there is no longer any free water in the solution, resulting in a molten matrix.

Then approximately 0 to 5 wt% of a neutral inorganic salt such as anhydrous sodium chloride can be added to the mixing tank to increase the viscosity.

Next, 5 to 12.6 wt% of a non-ionic surfactant such as a benzyl ether or a linear polyethoxylated alcohol is added to the mix tank. Mixing should take place for a sufficient time to homogenize the mix tank contents. Then, approximately 20 to 34 wt% of a complexing agent such as sodium tripolyphosphate can be added to the mix tank. Alternatively, a sodium tripolyphosphate surfactant premix can be added at this time.

Then, approximately 21 to 35% by weight of a sodium tripolyphosphate surfactant premix may be introduced into the mixing tank. The "sodium tripolyphosphate surfactant premix" is as defined in Example 1. Phosphate-containing compositions are preferably added late in the process added to minimize phosphate reversion.

Then approximately 0 to 0.05 wt.% of a dye may be added to the mix tank contents. To protect the dye, it is typically added toward the end of the process, but not so late that there is insufficient time for adequate mixing of the dye with the mix tank contents. Optional ingredients are typically added to the mix tank after the addition of the nonionic surfactant but before the addition of the complexing agent.

After the complexing agent, such as a polyphosphate, and/or optional fillers or components (the polyphosphate is a preferred ingredient) are added, the mixture may be cooled. Mixing may be continuous during any dissolution, cooling and thickening steps. The cooled and thickened mixture is poured into a container-shaped mold to a level that at least partially covers the mold side walls. As the mixture cools further, it will harden to form a molded composition. It is believed that the hardening is due essentially to the cooling. After it has hardened, the molded detergent is surrounded by and in contact with the mold on all sides except its top, which remains exposed.

The present invention will be further understood with the aid of the following specific examples which illustrate the composition, form and method of manufacture of the solid cast low temperature detergent containing article of the present invention. It is to be understood that many variations in the composition, form and method of preparation of the poured detergent would be obvious to those skilled in the art. The following examples, in which parts and percentages are by weight unless otherwise indicated, are for illustrative purposes only.

example 1

A 10,000 pound (4536 kilogram) portion of the solid cast low temperature detergent composition of the present invention was prepared using the following procedure. Equipment used was a 1000 gallon (3785 liter) stainless steel lined mix tank with a recycle line, a positive displacement pump, a variable speed agitator, and a second mix tank.

11.997 weight percent of a 50% aqueous sodium hydroxide solution was added to the 1000 gallon (3785 liter) mixing tank. The adjustable speed agitator was then set to its lowest setting. The contents of the mixing tank were then heated to a temperature in the range of 150 to 165ºF (65.6 to 73.9ºC). Heating was then discontinued at that point. 2.00 weight percent of soft water was then added to the mixing tank. The agitator speed was then increased to 75 rpm. Recirculation of the mixing tank contents was then begun.

The contents of the mixing tank were then heated to a temperature in the range of 185 to 190ºF (85.0 to 87.8ºC). 7,000 wt.% of a low molecular weight polyacrylic acid was slowly added at a rate of 25 pounds (11.3 kilograms) per minute. The addition of the polyacrylic acid resulted in an exothermic reaction which raised the temperature of the contents of the mix tank to 220 to 230ºF (104.4 to 110.0ºC). The mix tank contents were then stirred for 15 minutes.

Next, 40,000 wt% sodium hydroxide beads were slowly added to the mix tank. The agitation speed was then varied but did not exceed 110 rpm. The mix tank contents were then cooled to 150 to 155ºF (65.6 to 68.3ºC) with the agitation speed reduced as necessary to prevent turbulence.

Then 3.000 wt% anhydrous sodium chloride was added to the mix tank. Next, 0.003 wt% Pontamine Red (a dye) was premixed with 1 gallon (3.785 liters) of water and added to the mix tank.

Then 9,000 wt.% of a benzyl ether of a linear polyethoxylated alcohol was introduced into the mix tank by pumping this nonionic surfactant below the surface of the mix tank contents. The agitation speed was then increased to 130 rpm. The mix tank contents were then cooled to 145 to 150ºF (62.7 to 65.6ºC).

1110 lbs. (503.5 kilograms) of the mix tank contents were then transferred to the second 150 gallon (567.8 liter) mix tank. Agitation was then begun. The temperature in the second mix tank was between 143 to 150ºF (61.7 to 65.6ºC). Then 27,000 wt.% of a sodium tripolyphosphate surfactant premix (described below) was added to the second 150 gallon (567.8 liter) mix tank. The agitation speed was then increased to increased as necessary to avoid the formation of lumps. Stirring was continued for 5 minutes after de-lumping. Then the stirring speed was reduced to 90 to 100 rpm. The temperature was maintained in the range of 143 to 150ºF (61.7 to 65.6ºC).

Just before packaging began, continuous feeds of stock solution and sodium tripolyphosphate surfactant premix were added to the second 150-gallon (567.8-liter) mix tank.

The flow of stock solution ranged from approximately 4 lb. 11 oz. (2.1 kilograms) per 5 seconds to 5 lb. 3 oz. (2.4 kilograms) per 5 seconds. The flow of sodium tripolyphosphate surfactant premix ranged from approximately 3 lb. 5 oz. (1.5 kilograms) to 3 lb. 9 oz. (1.6 kilograms) in 10 seconds.

After the mixture had thickened but was still pourable, 8 pounds (3.6 kilograms) were poured into a container-shaped mold made from a polyethylene container measuring approximately 9 inches (22.9 cm) in diameter and 6 inches (15.2 cm) high.

The molds containing the product were sealed and passed through a water spray cooling tunnel for over 1 hour while the product cured. The water spray used had a temperature of 60ºF (15.6ºC) and a pressure of 15 p.s.i. (103.4 kPa).

The weight ratios of the starting materials used in Example 1 were as follows: NaOH, 50% starting material wt% in the formulation soft water polyacrylic acid (low molecular weight) sodium hydroxide beads anhydrous sodium chloride Pontamine Red (a dye) benzyl ether of a linear polyethoxylated alcohol sodium tripolyphosphate surfactant premix

Although this product can be used as a detergent without additional additives, additional components may be included, as previously described.

The sodium hydroxide 50% used in the examples refers to an aqueous 50 wt% sodium hydroxide solution. Such solutions are readily available commercially.

The low molecular weight polyacrylic acid used in the examples has the following properties:

Characteristics

Appearance: water-clear to golden yellow, cloudy liquid

Activity: 48 - 50% aqueous solution

Calcium chelation: 900 - 1100 meq. Ca

pH, 100%: 1.5 to 2.0

Solubility: easily soluble in water at pH values greater than 4

Molar weight: -3000 (intrinsic viscosity)

Equivalent mass: 72

The anhydrous sodium hydroxide beads used in the examples were of such a size that 80% of the beads had a 250 um (60 US mesh) sieve. Anhydrous sodium hydroxide beads are commercially available from numerous sources.

The benzyl ether of a linear polyethoxylated alcohol used in the examples had the following properties:

Characteristics

Appearance: light golden yellow solid

Activity: 100%

Melting point: 30 - 35ºC

Cloud point (1% solution): 60 - 64ºF (15.6 - 17.8ºC)

Hydroxyl number: max. 5

pH (1% solution): 6.7 - 8.0

Refractive index @35ºC: 1.4700 - 1.4725

Surface tension (0.1% solution): 33.9 dyn/cm (3.39 cN/m)

Ross-Miles foam (0.1% solution): Initial: 5 mm

5 mins: 0

The sodium tripolyphosphate surfactant premix used in the examples comprised 97.100% coarse granular sodium tripolyphosphate and 2.900% surfactant premix. The surfactant premix comprised 86.00% of a propylene oxide nonionically terminated ethylene oxide-propylene oxide block having the following properties:

Characteristics

Appearance: golden yellow liquid

Activity: 100%

Cloud point (1% solution): 85 - 90ºF (29.4 - 32.2ºC)

Hydroxyl number: 22 - 32

pH (1% solution): 9.5 - 10.7

Refractive index @25ºC: 1.4570 - 1.4590

Surface tension (0.1% solution): 42.0 dyn/cm (4.20 cN/m)

Density @25ºC: 1.037

Density: 8.7 lbs/gal. (1.04 kg/liter)

and 14% of a defoamer which was a mixture of mono- and dialkyl acid phosphate esters in which the alkyl groups were linear. The defoamer was rich in monoalkyl acid esters; the alkyl group was C₁₆.

The defoamer had the following properties:

Characteristics

Appearance: Light brown solid

Activity: 100%

Melting point: 55 - 63ºC

pH (1% solution): 2.3 - 3.2

Solubility: Completely soluble in mineral spirits, primary alcohols, aromatics and many non-ionic surfactants. Slightly soluble in water.

Typical composition: 6 - 9% orthophosphate

57 - 64% monoalkyl acid phosphate

7 - 11% dialkyl acid phosphate

16 - 30% linear alcohol

Example 2

A cured cast detergent was prepared according to the procedure set forth in Example 1.

The weight ratios of the starting materials used in Example 2 were as follows: Starting Material % in the Formulation NaOH, 50% Soft Water Polyacrylic Acid (Low Molecular Weight) Sodium Hydroxide Beads Anhydrous Sodium Chloride Pontamine Red (a dye) Benzyl Ether of a Linear Polyethoxylated Alcohol Sodium Tripolyphosphate Surfactant Premix

Example 3

A cured cast detergent was prepared according to the method outlined in Example 1.

The weight ratios of the starting materials used in Example 3 were as follows: Starting Material % in the Formulation NaOH, 50% Soft Water Polyacrylic Acid (Low Molecular Weight) Sodium Hydroxide Beads Anhydrous Sodium Chloride Pontamine Red (a dye) Benzyl Ether of a Linear Polyethoxylated Alcohol Sodium Tripolyphosphate Surfactant Premix

The above discussion, description and examples provide sufficient information for understanding the invention. Basis. The invention resides in the claims appended hereto.

Claims (13)

1. A solid cast detergent composition which comprising: (a) 5 to 12.6% by weight of a non-ionic surfactant; (b) 10 to 60 percent by weight of an alkali metal hydroxide; (c) 10 to 50% by weight of a water softener; and (d) S to 30% by weight water of hydration; wherein each percentage is based on the cast composition. 2. The cast composition of claim 1, further comprising a container-shaped disposable package surrounding all but one side of the detergent composition. 3. A cast composition according to claim 2, wherein the package is the mold in which the composition was cast and solidified. 4. A molded composition according to claim 3, further comprising a cover attached to the container-shaped package. 5. A cast composition according to claim 1, wherein the composition additionally comprises a defoamer. 6. The solid cast detergent composition of Claim 1, further comprising: (a) 2 to 7 percent by weight of a polyelectrolyte; and (b) up to 1% by weight of a defoaming agent; wherein the alkali metal hydroxide is present in an amount of 20 to 50 weight percent; the water softener is present in an amount of 15 to 34 weight percent and comprises a condensed alkali metal phosphate; and the water of hydration is present in an amount of 10 to 20 weight percent of the cast composition. 7. A method of dispensing detergent into a washing area for washing goods using the solid cast detergent composition according to claim 2, comprising the following steps: (a) placing the solid cast detergent composition in a detergent dispenser having a spray device in a position, relative to the horizontal and the spray device, for downwardly dispensing detergent from the detergent composition to the washing area of a machine for washing goods, the side of the solid cast detergent composition not surrounded by the container-shaped packaging being located inside the detergent dispenser and being oriented so as to provide the interior of the detergent dispenser with substantially an unsurrounded, exposed, leachable surface of the solid cast detergent composition; (b) directing a spray of aqueous liquid from the spraying means onto the unenclosed, exposed, leachable surface to dissolve the detergent composition at a substantially uniform rate and thereby produce a forming an aqueous liquid detergent containing the detergent composition in the aqueous liquid which flows downwardly from the unenclosed, exposed, leachable surface substantially simultaneously with the occurrence of the spray; (c) allowing the downwardly flowing aqueous liquid detergent to flow substantially simultaneously out of the detergent dispenser and into the washing area for the purpose of washing goods therein; and (d) controlling the duration of step (b), thereby controlling the amount of aqueous liquid detergent composition flowing into the washing zone and thereby controlling the concentration of the detergent composition in the washing zone. 8. A method according to claim 7, wherein the non- surrounded, exposed leachable surface faces towards the spraying device. 9. A method according to claim 8, wherein the solid cast detergent composition according to step (a) is placed in an inverted position above the spraying device so that the unenclosed exposed leachable surface faces downwardly towards the spraying device. 10. A method according to claim 7, wherein in step (a) the solid cast detergent composition is placed in an inverted position above the spraying device and a spray is directed generally perpendicularly at the unenclosed, exposed leachable area. 11. A process for forming a solid cast detergent composition, which includes the following steps: (a) heating a 40 to 75 weight percent aqueous solution of an alkali metal hydroxide to 150 to 165° F (65.6 to 73.90 C) and adding 30 to 40 weight percent anhydrous alkali metal hydroxide platelets to the solution; (b) dispersing from 5 to 12.6% by weight of a nonionic surfactant in the solution; (c) dispersing from 10 to 50 percent by weight of a water softening agent in the solution; (d) thickening the solution and agitating the solution during thickening to form a pourable uniform dispersion; (e) pouring the uniform dispersion into the container-shaped mold and at least partially filling the mold; and (f) allowing the thickened dispersion to harden in the mold to form a uniform, solid, cast detergent, wherein at least one surface of the cast detergent is left uncovered by the container-shaped mold. 12. The process of claim 11, wherein the alkali metal hydroxide is sodium hydroxide. 13. The method of claim 12, wherein the water softener is sodium tripolyphosphate.