Detergent tablet

A detergent tablet comprising a non-compressed, gelatinous portion, wherein the gelatinous portion comprising a thickening system and at least one detergent active. The thickening system preferably includes a non-aqueous diluent and a gelling agent and the detergent active is preferably selected from the group consisting of enzymes, surfactants, effervescing agents, bleaching agents, silver care agents, builders, and mixtures thereof. The non-compressed, gelatinous portion, may contain one, two or a plurality of non-compressed, gelatinous portions, all of which comprise a thickening system and at least one detergent active.

 

What is claimed is:

1. A detergent tablet comprising, a non-compressed, gelatinous body which comprises:

i) a first non-compressed, gelatinous portion, said first gelatinous portion comprising a thickening system and at least one detergent active; and

ii) a second non-compressed, gelatinous portion, said second gelatinous portion comprising a thickening system and at least one detergent active; wherein the thickening system in (i) and (ii) comprises a mixture of a non-aqueous diluent and a gelling agent; wherein said first gelatinous portion is formulated so that at least about 80% of said detergent active is delivered to the wash within the first 5 minutes of a domestic wash process; and wherein the release of said detergent active in said second gelatinous portion is delayed by at least five minutes.

2. The detergent tablet according to claim 1 wherein said frist gelatinous portion is formulated so that at least about 90% of said detergent active is delivered to the wash within the first 3 minutes of a domestic wash process.

3. The detergent tablet according to claim 1 wherein said detergent active is selected from the group consisting of surfactants, enzymes, bleaching agents, disrupting agents, effervescing agents, silver care agents, builders, silicates, pH control agents or buffers, and mixtures thereof.

4. The detergent tablet according to claim 1 wherein said gelatinous body further includes a structure modifying agent.

5. A detergent tablet according claim 1 wherein said detergent tablet has a shape selected from the group consisting of, concave, convex, cubic, rectangular prismic, cylindrical, spheroidal, frustum of a cone, disc, pyramodial, tetrahedral, dodecahedral, octahedral, conical, ellipsoidal, figure eight, and rhombohedral.

6. A detergent tablet according to claim 1 wherein said detergent tablet has at least two non-compressed, gelatinous portions and the release of said detergent active in one of said non-compressed, gelatinous portions is delayed until after wash rinse cycle.

7. A method of washing tableware in a domestic automatic dishwashing appliance, said method comprising treating the soiled tableware in an automatic dishwasher with said detergent tablet according to claim 1.

8. A method of laundering fabric said method comprising treating the fabric with said detergent tablet according to claim 1.

9. A detergent tablet comprising a non-compressed, gelatinous body comprising a plurality of non-compressed, gelatinous portions, wherein each gelatinous portion comprises a thickening system and at least one detergent active; wherein the thickening system comprises a mixture of a non-aqueous diluent and a gelling agent; wherein at least one of said plurality of non-compressed, gelatinous portions is formulated so that at least about 80% of said detergent active is delivered to the wash within the first 5 minutes of a domestic wash process; and wherein the release of said detergent active in one of said non-compressed, gelatinous portion is delayed by at least five minutes.

10. The detergent tablet according to claim 9 wherein said detergent active is selected from the group consisting of surfactants, enzymes, bleaching agents, disrupting agents, effervescing agents, silver care agents, builders, silicates, pH control agents or buffers, and mixtures thereof.

11. A detergent tablet according to claim 9 wherein said detergent tablet has at least two non-compressed, gelatinous portions and the release of said detergent active in one of said non-compressed, gelatinous portions is delayed by at least seven minutes.

TECHNICAL FIELD

The present invention relates to non-compressed detergent tablets.

BACKGROUND OF THE INVENTION

Detergent compositions in tablet form are known in the art. Detergent compositions in tablet form hold several advantages over detergent compositions in particulate or liquid form, such as ease of use and handling, convenient dosing, ease of transportation and storage. Due to these advantages, detergent compositions in tablet form are becoming increasingly popular with consumers of detergent products.

Detergent tablets are most commonly prepared by pre-mixing the components and forming the pre-mixed components into a tablet via the use of a tablet press and compression of the components. However, traditional tablet compression processes have significant drawbacks, including but not limited to the fact that selected components of a detergent composition may be adversely affected by the compression pressure in the tablet press. Accordingly, these selected components were not typically included in prior art detergent tablets without sustaining a loss in performance. In some cases, these selected components may even have become unstable or inactive as a result of the compression.

In addition, as the components of the detergent composition are compressed in the tablet press, they are brought into close proximity with one another resulting in the reaction of selected component, instability, inactivity or exhaustion of the active form of the components.

To avoid the above mentioned drawbacks, prior art detergent tablets have attempted to separate components of the detergent composition that may potentially react with each other when the detergent composition is compressed into tablet form. Separation of the components has been achieved by, for example, preparing multiple-layer tablets wherein the reactive components are contained in different layers of the tablet or encapsulation and coating of reactive components. These prior art multiple-layer tablets are traditionally prepared using multiple compression steps. Accordingly, layers of the tablet which are subjected to more than one compression step may be subjected to a cumulative and potentially greater overall compression pressure. In addition, an increase in compression pressure of the tabletting press is known to decrease the rate of dissolution of the tablet with the effect that such multiple layer tablets may not dissolve satisfactorily in use. Nor is there any significant variation in the dissolution rates of the multiple layers.

Accordingly, the need remains for an improved detergent tablet which can deliver active detergent ingredients to a domestic wash process thereby delivering superior performance benefits.

SUMMARY OF THE INVENTION

This need is met by the present invention wherein a detergent tablet having a non-compressed gelatinous body is provided. The tablet of the present invention provides a superior delivery mechanism for detergent components. In addition, the detergent tablet of the present invention provides superior cleaning performance, particularly in domestic automatic dishwashing machines over the tablets of the prior art.

According to a first embodiment of the present invention, a detergent tablet is provided. The tablet comprises a non-compressed, gelatinous body, the gelatinous body comprising a thickening system and at least one detergent active and wherein the gelatinous body is formulated so that at least about 80% of the detergent active is delivered to the wash within the first 5 minutes of a domestic wash process.

According to a second embodiment of the present invention, a detergent tablet is provided. The tablet comprises a non-compressed, gelatinous body, the gelatinous body comprising a thickening system and at least one detergent active and the detergent tablet has a dissolution rate of greater than about 0.33 g/min as determined using the SOTAX dissolution test method.

According to a third embodiment of the present invention, a detergent tablet is provided. The tablet comprises a non-compressed, gelatinous body, which comprises:

i) a first non-compressed, gelatinous portion, the first gelatinous portion comprising a thickening system and at least one detergent active; and

ii) a second non-compressed, gelatinous portion, the second gelatinous portion comprising a thickening system and at least one detergent active; and wherein the first gelatinous body is formulated so that at least about 80% of said detergent active is delivered to the wash within the first 5 minutes of a domestic wash process.

According to a fourth embodiment of the present invention, a detergent tablet is provided. The tablet comprises a non-compressed, gelatinous body, which comprises:

i) a first non-compressed, gelatinous portion, the first gelatinous portion comprising a thickening system and at least one detergent active; and

ii) a second non-compressed, gelatinous portion, the second gelatinous portion comprising a thickening system and at least one detergent active; and wherein the detergent tablet is formulated so that at least about 80% of said detergent active is delivered to the wash within the first 5 minutes of a domestic wash process.

According to a fifth embodiment of the present invention, a detergent tablet is provided. The tablet comprises a non-compressed, gelatinous body, which comprises a plurality of non-compressed, gelatinous portions, wherein each gelatinous portion comprises a thickening system and at least one detergent active; and wherein at least one of said plurality of non-compressed, gelatinous portions is formulated so that at least about 80% of said detergent active is delivered to the wash within the first 5 minutes of a domestic wash process.

According to a sixth embodiment of the present invention, a detergent tablet is provided. The tablet comprises a non-compressed, gelatinous body, which comprises a plurality of non-compressed, gelatinous portions, wherein each gelatinous portion comprises a thickening system and at least one detergent active; and wherein said detergent tablet is formulated so that at least about 80% of said detergent active is delivered to the wash within the first 5 minutes of a domestic wash process.

The detergent active in the detergent tablet, non-compressed, gelatinous body or in any of the non-compressed, gelatinous portions may be selected from the group consisting of surfactants, enzymes, bleaching agents, effervescing agents, silver care agents, builders, silicates, pH control agents or buffers, enzymes, alkalinity sources, colorants, perfume, lime soap dispersants, organic polymeric compounds including polymeric dye transfer inhibiting agents, crystal growth inhibitors, heavy metal ion sequestrants, metal ion salts, enzyme stabilizers, corrosion inhibitors, suds suppressers, solvents, fabric softening agents, optical brighteners and hydrotropes and mixtures thereof, with enzymes and disrupting agents being the most preferred. When a disrupting agent is included, the disrupting agent is preferably a salt of carbonate or bicarbonate and an organic acid.

In alternative embodiments, the detergent tablet, non-compressed, gelatinous body or in any of the non-compressed, gelatinous portions may contain at least about 15% suspended solids and more preferably at least about 40% of the gel portion is a suspended solid. The detergent tablet, non-compressed, gelatinous body or in any of the non-compressed, gelatinous portions may further includes a swelling/adsorbing agent.

The thickening system of the present invention preferably comprises a mixture of a non-aqueous diluent or solvent and a gelling agent. The gelling agent may be selected from the group consisting of castor oil derivatives, polyethylene glycol and mixtures thereof and is preferably polyethylene glycol. The non-aqueous diluent may be selected from the group consisting of low molecular weight polyethylene glycols, glycerol and modified glycerols, propylene glycol, alkyleneglycol alkyl ethers and mixtures thereof and is preferably dipropyleneglycol butylether, propylene glycol or glycerol triacetate.

Accordingly, it is an object of the present invention to provide a detergent tablet having a non-compressed, gelatinous body or a plurality of non-compressed, gelatinous portion. It is a further object of the present invention to provide a detergent tablet, non-compressed, gelatinous body or in any of the non-compressed, gelatinous portions which can quickly and efficiently deliver detergent actives to a domestic wash process. It is still further an object of the present invention to provide a detergent tablet, non-compressed, gelatinous body or a plurality of non-compressed, gelatinous portions which are pumpable, flowable gels at slightly elevated temperatures yet harden or thicken to maintain their form at ambient temperatures, particularly when shear is removed from the gel. These, and other objects, features and advantages of the present invention will be readily apparent to one of ordinary skill in the art from the following detailed description and the appended claims.

All percentages, ratios and proportions herein are by weight, unless otherwise specified. All temperatures are in degrees Celsius (.degree. C.) unless otherwise specified. All documents cited are in relevant part, incorporated herein by reference.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises a detergent tablet and in particular a detergent tablet for laundry or automatic dishwashing which has a gelatinous body or a plurality of gelatinous portions which is non-compressed. The use of the non-compressed, gelatinous body or a plurality of non-compressed, gelatinous portions provides a superior delivery mechanism for detergent active agents into the domestic wash process. The non-compressed, gelatinous body or a plurality of non-compressed, gelatinous portions provides unique properties of rapid dissolution or dispersion thereby providing for the earliest possible delivery of detergent active agents into the domestic wash process.

Accordingly, by way of the present invention, active detergent components of a detergent tablet previously adversely affected by the compression pressure used to form the tablets may now be included in a detergent tablet. Examples of these components include bleaching agents and enzymes. In addition, these active detergent components may be separated from one another by having one or more compatible components contained in the any of the plurality of non-compressed, gelatinous portions and one or more compatible components contained in any of the plurality of non-compressed, gelatinous portions of the tablet. Examples of components that may interact and may therefore require separation include bleaching agents, bleach activators or catalyst and enzymes; bleaching agents and bleach catalysts or activators; bleaching agents and surfactants; alkalinity sources, perfumes and enzymes.

It may be advantageous to provide a plurality of non-compressed, gelatinous portions such that they dissolve in the wash water with different dissolution rates. By controlling the rate of dissolution of each portion relative to one another, and by selection of the active detergent components in the respective portions, their order of release into the wash water can be controlled and the cleaning performance of the detergent tablet may be improved. For example it is often preferred that enzymes are delivered to the wash prior to builders and/or bleaching agent and/or bleach activator. It may also be preferred that a source of alkalinity is released into the wash water more rapidly than other components of the detergent tablet. It is also envisaged that it may be advantageous to prepare a detergent tablet according to the present invention wherein the release of certain components of the tablet is delayed relative to other components.

It is possible for one or more detergent actives in a non-compressed, gelatinous portion to be delayed in its release. When the detergent tablet has two or more non-compressed, gelatinous portions at least one detergent active, preferably one, may be delayed in its release for at least five minutes, preferably seven minutes, into the wash solution. It is also possible for the release of the detergent active to be delayed until the after wash rinse cycle, such as the after wash rinse cycle in a washing machine or in an automatic dishwashing machine. This delayed release allows for the addition of detergent actives which are useful during the rinse cycle such as surfactants, fabric softeners, bleaches, etc.

The tablet may also comprise non-compressed, gelatinous body or a plurality of non-compressed, gelatinous portions. For example, a plurality of compressed portions may be arranged in horizontal layers. Thus, there may be a non-compressed, gelatinous body or a plurality of non-compressed, gelatinous portions each comprising an active detergent component and where different portions may comprise different active detergent components or mixtures of components. Such a plurality of non-compressed, gelatinous portions may be advantageous, enabling a tablet to be produced which has for example, a first and second and optional subsequent portions so that they have different rates of dissolution. Such performance benefits are achieved by selectively delivering active-detergent components into the wash water at different times.

It is preferred that the detergent tablets, of the present invention be free from foul or noxious odors. If present such odors may be masked or removed. This includes the addition of masking agents, perfumes, odor absorbers, such as cyclodextrins, etc.

The detergent tablet may be transparent, opaque or any possible shade in between these two extremes. When there are more than one non-compressed, gel portion present in the detergent tablet it is possible for each of the gel portions to have the same or different degree of transparency, i.e. ranging from totally transparent to opaque. However, it is preferred that they are different.

The detergent tablets described herein are preferably between 15 g and 100 g in weight, more preferably between 18 g and 80 g in weight, even more preferably between 20 g and 60 g in weight. The detergent tablet described herein that are suitable for use in automatic dishwashing methods are most preferably between 20 g and 40 g in weight. Detergent tablets suitable for use in fabric laundering methods are most preferably between 40 g and 100 g, more preferably between 40 g and 80 g, most preferably between 40 g and 65 g in weight.

The non-compressed, gelatinous body, of the detergent tablets described herein can have a dissolution rate of faster than 0.33 g/min, preferably faster than 0.5 g/min, more preferably faster than 1.00 g/min, even more preferably faster than 2.00 g/m, most preferably faster than 2.73 g/min. Dissolution rate is measured using the SOTAX dissolution test method. For the purposes of the present invention dissolution of detergent tablets is achieved using a SOTAX (tradename) machine; model number AT7 available from SOTAX.

SOTAX Dissolution Test Method: The SOTAX machine consists of a temperature controlled waterbath with lid. 7 pots are suspended in the water bath. 7 electric stirring rods are suspended from the underside of the lid, in positions corresponding to the position of the pots in the waterbath. The lid of the waterbath also serves as a lid on the pots.

The SOTAX waterbath is filled with water and the temperature gauge set to 50.degree. C. Each pot is then filled with 1 liter of deionised water and the stirrer set to revolve at 250 rpm. The lid of the waterbath is closed, allowing the temperature of the deionised water in the pots to equilibrate with the water in the waterbath for 1 hour.

The tablets are weighed and one tablet is placed in each pot, the lid is then closed. The tablet is visually monitored until it completely dissolves. The time is noted when the tablet has completely dissolved. The dissolution rate of the tablet is calculated as the average weight (g) of tablet dissolved in deionised water per minute.

Gel Portion

The non-compressed, gelatinous body or the plurality of non-compressed, gelatinous portions comprises a thickening system and at least one detergent active agent. The non-compressed, gelatinous body or the plurality of non-compressed, gelatinous portions is preferably formulated such that the detergent active ingredient is essentially completely delivered in a short period of time. The non-compressed, gelatinous body, at least one of the plurality of non-compressed, gelatinous portions or the detergent tablet can be formulated so that at least about 80% of the detergent active is delivered to the wash of a domestic washing process within the first 5 minutes, more preferably at least about 90% in the first 3 minutes and even more preferably about 95% within the first 2 minutes as measured from the first point at which the tablet is completely immersed in water, particularly in cold water temperatures, such as, e.g., 25.degree. C. It is preferred that the non-compressed, gelatinous body, at least one of the plurality of non-compressed, gelatinous portions or the detergent tablet be capable of dissolving in cold water, i.e. less than 30.degree. C., preferably from about 10.degree. C. to about 28.degree. C. Thus, the tablet of the present invention is particularly effective at delivering detergent actives in varying water temperatures including cold water.

Alternatively, the detergent can have a dissolution rate of faster than 0.33 g/min, preferably faster than 0.5 g/min, more preferably faster than 1.00 g/min, even more preferably faster than 2.00 g/m, most preferably faster than 2.73 g/min. Dissolution rate is measured using the SOTAX dissolution test method. For the purposes of the present invention dissolution of detergent tablets is achieved using a SOTAX (tradename) machine; model number AT7 available from SOTAX.

The detergent tablet, the non-compressed, gelatinous body or any of the plurality of non-compressed, gelatinous portions may include solid ingredients which are dispersed or suspended within the detergent tablet, the non-compressed, gelatinous body or any of the plurality of non-compressed, gelatinous portions. The solid ingredients aid in the control of the viscosity of the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions formulation in conjunction with the thickening system. In addition, solid ingredients may act to optionally disrupt the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions thereby aiding in dissolution of the detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions. When included, the detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions comprises at least about 15% solid ingredients, more preferably at least about 30% solid ingredients and most preferably at least about 40% solid ingredients. However, due to pumpability and other processing concerns, the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions of the present invention typically do not include more than about 90% solid ingredients.

The detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions may additionally contain a drying agent. Any, conventional drying agent may be used. See Vogels Text book of Practical Organic Chemistry, 5.sup.th Edition (1989) Longman Scientific & Technical, pp. 165-168, incorporated herein by reference. For example, suitable drying agents are anhydrous CaSO.sub.4, anhydrous Na.sub.2 SO.sub.4, sodium sulfite, calcium chloride and MgSO.sub.4. The selection of suitable drying agents may depend on the end use of the tablet. A drying agent for a detergent tablet for an automatic dishwashing composition for low temperatures is preferably sodium sulfite or calcium chloride but anhydrous CaSO.sub.4, may be used for higher use temperatures. When present drying agents will range from about 0.1% to about 15%, more preferably from about 0.1% to about 10%, even more preferably from about 0.5% to about 7%, by weight of the tablet.

In a preferred embodiment the detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions are coated with a coating layer. The coating layer preferably comprises a material that becomes solid on contacting the detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions within preferably less than 15 minutes, more preferably less than 10 minutes, even more preferably less than 5 minutes, most preferably less than 60 seconds. Preferably the coating layer is water-soluble. Preferred coating layers comprise materials selected from the group consisting of fatty acids, alcohols, diols, esters and ethers, adipic acid, carboxylic acid, dicarboxylic acid, polyvinyl acetate (PVA), polyvinyl pyrrolidone (PVP), polyacetic acid, polyethylene glycol (PEG) and mixtures thereof. Preferred carboxylic or dicarboxylic acids preferably comprise an even number of carbon atoms. Preferably carboxylic or dicarboxylic acids comprise at least 4, more preferably at least 6, even more preferably at least 8 carbon atoms, most preferably between 8 and 13 carbon atoms. Preferred dicarboxylic acids include adipic acid, suberic acid, azelaic acid, subacic acid, undecanedioic acid, dodecandioic acid, tridecanedioic and mixtures thereof Preferred fatty acids are those having a carbon chain length of from C12 to C22, most preferably from C18 to C22. The coating layer may also preferably comprise a disrupting agent. Where present the coating layer generally present at a level of at least about 0.05%, more preferably at least about 0.1%, even more preferably at least about 1%, even more preferably still at least about 2% or even at least about 5% of the detergent tablet.

Thickening System

As noted earlier, the detergent tablet of the present invention comprises thickening system in the non-compressed, gelatinous body, and in the plurality of non-compressed, gelatinous portions to provide the proper viscosity or thickness of the gel portion. The thickening system typically comprises a non-aqueous liquid diluent and an organic or polymeric gelling additive.

a) Liquid Diluent

The term "solvent" or "diluent" is used herein to connote the liquid portion of the thickening system. While some of the essential and/or optional components of the compositions herein may actually dissolve in the "solvent"-containing phase, other components will be present as particulate material dispersed within the "solvent"-containing phase. Thus the term "solvent" is not meant to require that the solvent material be capable of actually dissolving all of the detergent composition components added thereto. Suitable types of solvents useful in the non-aqueous thickening systems herein include alkylene glycol mono lower alkyl ethers, propylene glycols, ethoxylated or propoxylated ethylene or propylene, glycerol esters, glycerol triacetate, lower molecular weight polyethylene glycols, lower molecular weight methyl esters and amides, and the like.

A preferred type of non-aqueous solvent for use herein comprises the mono-, di-, tri-, or tetra- C.sub.2 -C.sub.3 alkylene glycol mono C.sub.2 -C.sub.6 alkyl ethers. The specific examples of such compounds include diethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monobutyl ether. Diethylene glycol monobutyl ether and dipropylene glycol monobutyl ether are especially preferred. Compounds of the type have been commercially marketed under the tradenames Dowanol, Carbitol, and Cellosolve.

Another preferred type of non-aqueous solvent useful herein comprises the lower molecular weight polyethylene glycols (PEGs). Such materials are those having molecular weights of at least about 150. PEGs of molecular weight ranging from about 200 to 600 are most preferred.

Yet another preferred type of non-aqueous solvent comprises lower molecular weight methyl esters. Such materials are those of the general formula: R.sup.1 --C(O)--OCH.sub.3 wherein R.sup.1 ranges from 1 to about 18. Examples of suitable lower molecular weight methyl esters include methyl acetate, methyl propionate, methyl octanoate, and methyl dodecanoate.

The non-aqueous organic solvent(s) employed should, of course, be compatible and non-reactive with other composition components, e.g., enzymes, used in the detergent tablets herein. Such a solvent component will generally be utilized in an amount of from about 10% to about 60% by weight. More preferably, the non-aqueous, low-polarity organic solvent will comprise from about 20% to about 50%,most preferably from about 30% to about 50% by weight.

b) Gelling Additive

As noted earlier, a gelling agent or additive is added to the non aqueous solvent of the present invention to complete the thickening system. To achieve the required phase stability and acceptable rheology of the gel, the organic gelling agent is generally present to the extent of a ratio of solvent to gelling agent in thickening system typically ranging from about 99:1 to about 1:1. More preferably, the ratios range from about 19:1 to about 4:1.

The preferred gelling agents of the present invention are selected from castor oil derivatives, polyethylene glycol, sorbitols and related organic thixatropes, organoclays, cellulose and cellulose derivatives, pluronics, stearates and stearate derivatives, sugar/gelatin combination, starches, glycerol and derivatives thereof, organic acid amides such as N-lauryl-L-glutamic acid di-n-butyl amide, polyvinyl pyrrolidone and mixtures thereof.

The preferred gelling agents include castor oil derivatives. Castor oil is a naturally occurring triglyceride obtained from the seeds of Ricinus Communis, a plant which grows in most tropical or subtropical areas. The primary fatty acid moiety in the castor oil triglyceride is ricinoleic acid (12-hydroxy oleic acid). It accounts for about 90% of the fatty acid moieties. The balance consists of dihydroxystearic, palmitic, stearic, oleic, linoleic, linolenic and eicosanoic moieties. Hydrogenation of the oil (e.g., by hydrogen under pressure) converts the double bonds in the fatty acid moieties to single bonds, thus "hardening" the oil. The hydroxyl groups are unaffected by this reaction.

The resulting hydrogenated castor oil, therefore, has an average of about three hydroxyl groups per molecule. It is believed that the presence of these hydroxyl groups accounts in large part for the outstanding structuring properties which are imparted to the gel compared to similar liquid detergent compositions which do not contain castor oil with hydroxyl groups in their fatty acid chains. For use in the compositions of the present invention the castor oil should be hydrogenated to an iodine value of less than about 20, and preferably less than about 10. Iodine value is a measure of the degree of unsaturation of the oil and is measured by the "Wijis Method," which is well-known in the art. Unhydrogenated castor oil has an iodine value of from about 80 to 90.

Hydrogenated castor oil is a commercially available commodity being sold, for example, in various grades under the trademark CASTORWAX.RTM. by NL Industries, Inc., Highstown, N.J. Other Suitable hydrogenated castor oil derivatives are Thixcin R, Thixcin E, Thixatrol ST, Perchem R and Perchem ST, made by Rheox, Laporte. Especially preferred is Thixatrol ST.

Polyethylene glycols when employed as gelling agents, rather than solvents, have a molecular weight range of from about 2000 to about 30000, preferably about 4000 to about 12000, more preferably about 6000 to about 10000.

Cellulose and cellulose derivatives when employed in the present invention preferably include: i) Cellulose acetate and Cellulose acetate phthalate (CAP); ii) Hydroxypropyl Methyl Cellulose (HPMC); iii)Carboxymethylcellulose (CMC); and mixtures thereof. The hydroxypropyl methylcellulose polymer preferably has a number average molecular weight of about 50,000 to 125,000 and a viscosity of a 2 wt. % aqueous solution at 25.degree. C. (ADTMD2363) of about 50,000 to about 100,000 cps. An especially preferred hydroxypropyl cellulose polymer is Methocel.RTM. J75MS-N wherein a 2.0 wt. % aqueous solution at 25.degree. C. has a viscosity of about 75,000 cps.

The sugar may be any monosaccharide (e.g. glucose), disaccharide (e.g. sucrose or maltose) or polysaccharide. The most preferred sugar is commonly available sucrose. For the purposes of the present invention type A or B gelatin may be used, available from for example Sigma. Type A gelatin is preferred since it has greater stability in alkaline conditions in comparison to type B. Preferred gelatin also has a bloom strength of between 65 and 300, most preferably between 75 and 100.

The non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions of the present invention may include a variety of other ingredients in addition to the thickening agent as herein before described and the detergent active disclosed in more detail below. Ingredients such as perfumes and dyes may be included as well as structure modifying agents. Structure modifying agents include various polymers and mixtures of polymers included polycarboxylates, carboxymethylcelluloses and starches to aid in adsorption of excess solvent and/or reduce or prevent "bleeding" or leaking of the solvent from the gel portion, reduce shrinkage or cracking of the gel portion or aid in the dissolution or breakup of the gel portion in the wash. In addition, hardness modifying agents may incorporated into the thickening system to adjust the hardness of the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions if desired. These hardness control agents are typically selected from various polymers, such as polyethylene glycol's, polyethylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, hydroxystearic acid and polyacetic acid and when included are typically employed in levels of less than about 20% and more preferably less than about 10% by weight of the solvent in the thickening system. For example, hardening agents, such as high molecular weight PEG, preferably of a molecular weight from 10,000 to 20,000 or possibly even higher molecular weight, can be added to decrease the hardening time of the non-compressed, non-encapsulating portion. Alternatively, water soluble polymeric materials such as of low molecular weight polyethylene glycols may be added to the mould to form an intermediate barrier layer prior to addition of the non-compressed, non-encapsulating portion when it is a gel. This speeds cooling and hardening of the gel by the melting/mixing of the water soluble polymeric material when the gel is added to the at least one mould. In addition, the intermediate layer may act as a barrier to prevent ingredients from the gel mixing or bleeding into the compressed portion.

Addition of an alkaline material, such as sodium or potassium hydroxide can also speed in hardening of the non-compressed, non-encapsulating portion when it is a gel. Preferably, these alkaline materials would be added to the mould before the addition of the gel. However, in alternative systems, the alkaline material may be added to the gel composition. These alkaline materials also have the advantage of acting as an additional alkalinity source that is discrete and would be slower dissolving and hence have a minimal impact on any effervescence system present in the non-compressed, non-encapsulating portion yet provide an alkalinity boost in the wash.

The non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions of the present invention is formulated so that the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions is pumpable and flowable at slightly elevated temperatures of around 30.degree. C. or greater to allow increased flexibility in producing the detergent tablet, but becomes highly viscous or hardens at ambient temperatures so that the shape of the detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions is maintained through shipping and handling of the detergent tablet. Such hardening of the detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions may achieved, for example, by (i) cooling to below the flowable temperature of the gel portion or the removal of shear; (ii) by solvent transfer, for example either to the atmosphere of the compressed body portion; or by (iii) by polymerisation of the gelling agent. Preferably, the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions is formulated such that the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions hardens to sufficiently so that the maximum force needed to push a probe into the detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions preferably ranges from about 0.5N to about 40N. This force may be characterised by measuring the maximum force needed to push a probe, fitted with a strain gauge, a set distance into the gel portion. The set distance may be between about 40 and about 80% of the total detergent tablet, non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions depth. This force can be measured on a QTS 25 tester, using a probe of 5 mm diameter. Typical forces measured are in the range of 1N to 25N.

Additionally, it is preferred that when a 48 hour old tablet is inverted, at ambient conditions, for 10 minutes, more preferably 30 minutes, even more preferably 2 hours, the non-compressed, gelatinous body, or any of the plurality of non-compressed, gelatinous portions do not drip or separate form the rest of the detergent tablet.

Detergent Actives

The detergent tablets described herein may include a variety of different detergent active components including, but not limited to, surfactants, enzymes, bleaching agents, effervescing agents, silver care agents, builders, silicates, pH control agents or buffers, enzymes, alkalinity sources, colorants, perfume, lime soap dispersants, organic polymeric compounds including polymeric dye transfer inhibiting agents, crystal growth inhibitors, heavy metal ion sequestrants, metal ion salts, enzyme stabilizers, corrosion inhibitors, suds suppressers, solvents, fabric softening agents, optical brighteners and hydrotropes and mixtures thereof.

Surfactants

Surfactants are preferred detergent active components of the compositions described herein. Suitable surfactants are selected from anionic, cationic, nonionic ampholytic and zwitterionic surfactants and mixtures thereof. Automatic dishwashing machine products should be low foaming in character and thus the foaming of the surfactant system for use in dishwashing methods must be suppressed or more preferably be low foaming, typically nonionic in character. Sudsing caused by surfactant systems used in laundry cleaning methods need not be suppressed to the same extent as is necessary for dishwashing.

A typical listing of anionic, nonionic, ampholytic and zwitterionic classes, and species of these surfactants, is given in U.S. Pat. No. 3,929,678 issued to Laughlin and Heuring on Dec., 30, 1975. A list of suitable cationic surfactants is given in U.S. Pat. No. 4,259,217 issued to Murphy on Mar. 31, 1981. A listing of surfactants typically included in automatic dishwashing detergent compositions is given for example, in EP-A-0414 549 and PCT Applications Nos. WO 93/08876 and WO 93/08874.

Detersive surfactants, when included in the fully-formulated detergent compositions afforded by the present invention comprises preferably at least about 0.01%, more preferably from about 0.5% to about 50%, by weight of detergent composition depending upon the particular surfactants used and the desired effects. In a highly preferred embodiment, the detersive surfactant comprises from about 0.5% to about 20% by weight of the composition.

The detersive surfactant can be nonionic, anionic, ampholytic, zwitterionic, or cationic. Mixtures of these surfactants can also be used. Preferred detergent compositions comprise anionic detersive surfactants or mixtures of anionic surfactants with other surfactants, especially nonionic surfactants.

Nonionic Surfactants

Particularly preferred surfactants in the preferred automatic dishwashing compositions (ADD) of the present invention are low foaming nonionic surfactants (LFNI). LFNI may be present in amounts from 0.01% to about 10% by weight, preferably from about 0.1% to about 10%, and most preferably from about 0.25% to about 4%. LFNIs are most typically used in ADDs on account of the improved water-sheeting action (especially from glass) which they confer to the ADD product. They also encompass non-silicone, nonphosphate polymeric materials further illustrated hereinafter which are known to defoam food soils encountered in automatic dishwashing.

Preferred LFNIs include nonionic alkoxylated surfactants, especially ethoxy-lates derived from primary alcohols, and blends thereof with more sophisticated surfactants, such as the polyoxypropylene/polyoxyethylene/polyoxypropylene (PO/EO/PO) reverse block polymers. The PO/EO/PO polymer-type surfactants are well-known to have foam suppressing or defoaming action, especially in relation to common food soil ingredients such as egg.

The invention encompasses preferred embodiments wherein LFNI is present, and wherein this component is solid at about 95.degree. F. (35.degree. C.), more preferably solid at about 77.degree. F. (25.degree. C.). For ease of manufacture, a preferred LFNI has a melting point between about 77.degree. F. (25.degree. C.) and about 140.degree. F. (60.degree. C.), more preferably between about 80.degree. F. (26.6.degree. C.) and 110.degree. F. (43.3.degree. C.).

In a preferred embodiment, the LFNI is an ethoxylated surfactant derived from the reaction of a monohydroxy alcohol or alkylphenol containing from about 8 to about 20 carbon atoms, with from about 6 to about 15 moles of ethylene oxide per mole of alcohol or alkyl phenol on an average basis.

A particularly preferred LFNI is derived from a straight chain fatty alcohol containing from about 16 to about 20 carbon atoms (C.sub.16 -C.sub.20 alcohol), preferably-a C.sub.18 alcohol, condensed with an average of from about 6 to about 15 moles, preferably from about 7 to about 12 moles, and most preferably from about 7 to about 9 moles of ethylene oxide per mole of alcohol. Preferably the ethoxylated nonionic surfactant so derived has a narrow ethoxylate distribution relative to the average.

The LFNI can optionally contain propylene oxide in an amount up to about 15% by weight. Other preferred LFNI surfactants can be prepared by the processes described in U.S. Pat. No. 4,223,163, issued Sep. 16, 1980, Builloty, incorporated herein by reference

Highly preferred ADDs herein wherein the LFNI is present make use of ethoxylated monohydroxy alcohol or alkyl phenol and additionally comprise a polyoxyethylene, polyoxypropylene block polymeric compound; the ethoxylated monohydroxy alcohol or alkyl phenol fraction of the LFNI comprising from about 20% to about 100%, preferably from about 30% to about 70%, of the total LFNI.

Suitable block polyoxyethylene-polyoxypropylene polymeric compounds that meet the requirements described hereinbefore include those based on ethylene glycol, propylene glycol, glycerol, trimethylolpropane and ethylenediamine as initiator reactive hydrogen compound. Polymeric compounds made from a sequential ethoxylation and propoxylation of initiator compounds with a single reactive hydrogen atom, such as C.sub.12-18 aliphatic alcohols, do not generally provide satisfactory suds control in the instant ADDs. Certain of the block polymer surfactant compounds designated PLURONIC.RTM. and TETRONIC.RTM. by the BASF-Wyandotte Corp., Wyandotte, Mich., are suitable in ADD compositions of the invention.

A particularly preferred LFNI contains from about 40% to about 70% of a polyoxypropylene/polyoxyethylene/polyoxypropylene block polymer blend comprising about 75%, by weight of the blend, of a reverse block co-polymer of polyoxyethylene and polyoxypropylene containing 17 moles of ethylene oxide and 44 moles of propylene oxide; and about 25%, by weight of the blend, of a block co-polymer of polyoxyethylene and polyoxypropylene initiated with trimethylolpropane and containing 99 moles of propylene oxide and 24 moles of ethylene oxide per mole of trimethylolpropane.

Suitable for use as LFNI in the ADD compositions are those LFNI having relatively low cloud points and high hydrophilic-lipophilic balance (HLB). Cloud points of 1% solutions in water are typically below about 32.degree. C. and preferably lower, e.g., 0.degree. C., for optimum control of sudsing throughout a full range of water temperatures.

LFNIs which may also be used include those POLY-TERGENT.RTM. SLF-18 nonionic surfactants from Olin Corp., and any biodegradable LFNI having the melting point properties discussed hereinabove.

These and other nonionic surfactants are well known in the art, being described in more detail in Kirk Othmner's Encyclopedia of Chemical Technology, 3rd Ed., Vol. 22, pp. 360-379, "Surfactants and Detersive Systems", incorporated by reference herein.

Preferred are ADD compositions comprising mixed surfactants wherein the sudsing (absent any silicone suds controlling agent) is less than 2 inches, preferably less than 1 inch, as determined by the disclosure below.

The equipment useful for these measurements are: a Whirlpool Dishwasher (model 900) equipped with clear plexiglass door, IBM computer data collection with Labview and Excel Software, proximity sensor (Newark Corp.--model 95F5203) using SCXI interface, and a plastic ruler.

The data is collected as follows. The proximity sensor is affixed to the bottom dishwasher rack on a metal bracket. The sensor faces downward toward the rotating dishwasher arm on the bottom of the machine (distance approximately 2 cm. from the rotating arm). Each pass of the rotating arm is measured by the proximity sensor and recorded. The pulses recorded by the computer are converted to rotations per minute (RPM) of the bottom arm by counting pulses over a 30 second interval. The rate of the arm rotation is directly proportional to the amount of suds in the machine and in the dishwasher pump (i.e., the more suds produced, the slower the arm rotation).

The plastic ruler is clipped to the bottom rack of the dishwasher and extends to the floor of the machine. At the end of the wash cycle, the height of the suds is measured using the plastic ruler (viewed through the clear door) and recorded as suds height.

The following procedure is followed for evaluating ADD compositions for suds production as well as for evaluating nonionic surfactants for utility. (For separate evaluation of nonionic surfactant, a base ADD formula, such as Cascade powder, is used along with the nonionic surfactants which are added separately in glass vials to the dishwashing machine.)

First, the machine is filled with water (adjust water for appropriate temperature and hardness) and proceed through a rinse cycle. The RPM is monitored throughout the cycle (approximately 2 min.) without any ADD product (or surfactants) being added (a quality control check to ensure the machine is functioning properly). As the machine begins to fill for the wash cycle, the water is again adjusted for temperature and hardness, and then the ADD product is added to the bottom of the machine (in the case of separately evaluated surfactants, the ADD base formula is first added to the bottom of the machine then the surfactants are added by placing the surfactant-containing glass vials inverted on the top rack of the machine). The RPM is then monitored throughout the wash cycle. At the end of the wash cycle, the suds height is recorded using the plastic ruler. The machine is again filled with water (adjust water for appropriate temperature and hardness) and runs through another rinse cycle. The RPM is monitored throughout this cycle.

An average RPM is calculated for the 1st rinse, main wash, and final rinse. The % RPM efficiency is then calculated by dividing the average RPM for the test surfactants into the average RPM for the control system (base ADD formulation without the nonionic surfactant). The RPM efficiency and suds height measurements are used to dimension the overall suds profile of the surfactant.

Nonionic Ethoxylated Alcohol Surfactant

The alkyl ethoxylate condensation products of aliphatic alcohols with from 1 to 25 moles of ethylene oxide are suitable for use herein. The alkyl chain of the aliphatic alcohol can either be straight or branched, primary or secondary, and generally contains from 6 to 22 carbon atoms. Particularly preferred are the condensation products of alcohols having an alkyl group containing from 8 to 20 carbon atoms with from 2 to 10 moles of ethylene oxide per mole of alcohol.

End-capped Alkyl Alkoxylate Surfactant

A suitable endcapped alkyl alkoxylate surfactant is the epoxy-capped poly(oxyalkylated) alcohols represented by the formula:

R.sub.1 O[CH.sub.2 CH(CH.sub.3)O].sub.x [CH.sub.2 CH.sub.2 O].sub.y [CH.sub.2 CH(OH)R.sub.2 ] (I)

wherein R.sub.1 is a linear or branched, aliphatic hydrocarbon radical having from 4 to 18 carbon atoms; R.sub.2 is a linear or branched aliphatic hydrocarbon radical having from 2 to 26 carbon atoms; x is an integer having an average value of from 0.5 to 1.5, more preferably 1; and y is an integer having a value of at least 15, more preferably at least 20.

Preferably, the surfactant of formula I, at least 10 carbon atoms in the terminal epoxide unit [CH.sub.2 CH(OH)R.sub.2 ]. Suitable surfactants of formula I, according to the present invention, are Olin Corporation's POLY-TERGENT.RTM. SLF-18B nonionic surfactants, as described, for example, in WO 94/22800, published Oct. 13, 1994 by Olin Corporation.

Ether-capped Poly(oxyalkylated) Alcohols

Preferred surfactants for use herein include ether-capped poly(oxyalkylated) alcohols having the formula:

R.sup.1 O[CH.sub.2 CH(R.sup.3)O].sub.x [CH.sub.2 ].sub.k CH(OH)[CH.sub.2 ].sub.j OR.sup.2

wherein R.sup.1 and R.sup.2 are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from 1 to 30 carbon atoms; R.sup.3 is H, or a linear aliphatic hydrocarbon radical having from 1 to 4 carbon atoms; x is an integer having an average value from 1 to 30, wherein when x is 2 or greater R.sup.3 may be the same or different and k and j are integers having an average value of from 1 to 12, and more preferably 1 to 5.

R.sup.1 and R.sup.2 are preferably linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from 6 to 22 carbon atoms with 8 to 18 carbon atoms being most preferred. H or a linear aliphatic hydrocarbon radical having from 1 to 2 carbon atoms is most preferred for R.sup.3. Preferably, x is an integer having an average value of from 1 to 20, more preferably from 6 to 15.

As described above, when, in the preferred embodiments, and x is greater than 2, R.sup.3 may be the same or different. That is, R.sup.3 may vary between any of the alklyeneoxy units as described above. For instance, if x is 3, R.sup.3 may be selected to form ethlyeneoxy(EO) or propyleneoxy(PO) and may vary in order of (EO)(PO)(EO), (EO)(EO)(PO); (EO)(EO)(EO); (PO)(EO)(PO); (PO)(PO)(EO) and (PO)(PO)(PO). Of course, the integer three is chosen for example only and the variation may be much larger with a higher integer value for x and include, for example, multiple (EO) units and a much small number of (PO) units.

Particularly preferred surfactants as described above include those that have a low cloud point of less than 20.degree. C. These low cloud point surfactants may then be employed in conjunction with a high cloud point surfactant as described in detail below for superior grease cleaning benefits.

Most preferred ether-capped poly(oxyalkylated) alcohol surfactants are those wherein k is 1 and j is 1 so that the surfactants have the formula:

R.sup.1 O[CH.sub.2 CH(R.sup.3)O].sub.x CH.sub.2 CH(OH)CH.sub.2 OR.sup.2

where R.sup.1, R.sup.2 and R.sup.3 are defined as above and x is an integer with an average value of from 1 to 30, preferably from 1 to 20, and even more preferably from 6 to 18. Most preferred are surfactants wherein R.sup.1 and R.sup.2 range from 9 to 14, R.sup.3 is H forming ethyleneoxy and x ranges from 6 to 15.

The ether-capped poly(oxyalkylated) alcohol surfactants comprise three general components, namely a linear or branched alcohol, an alkylene oxide and an alkyl ether end cap. The alkyl ether end cap and the alcohol serve as a hydrophobic, oil-soluble portion of the molecule while the alkylene oxide group forms the hydrophilic, water-soluble portion of the molecule.

These surfactants exhibit significant improvements in spotting and filming characteristics and removal of greasy soils, when used in conjunction with high cloud point surfactants, relative to conventional surfactants.

Generally speaking, the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention may be produced by reacting an aliphatic alcohol with an epoxide to form an ether which is then reacted with a base to form a second epoxide. The second epoxide is then reacted with an alkoxylated alcohol to form the novel compounds of the present invention. Examples of methods of preparing the ether-capped poly(oxyalkylated) alcohol surfactants are described below:

Preparation of C.sub.12/14 Alkyl Glycidyl Ether

A C.sub.12/14 fatty alcohol (100.00 g, 0.515 mol.) and tin (IV) chloride (0.58 g, 2.23 mmol, available from Aldrich) are combined in a 500 mL three-necked round-bottomed flask fitted with a condenser, argon inlet, addition funnel, magnetic stirrer and internal temperature probe. The mixture is heated to 60.degree. C. Epichlorhydrin (47.70 g, 0.515 mol, available from Aldrich) is added dropwise so as to keep the temperature between 60-65.degree. C. After stirring an additional hour at 60.degree. C., the mixture is cooled to room temperature. The mixture is treated with a 50% solution of sodium hydroxide (61.80 g, 0.773 mol, 50%) while being stirred mechanically. After addition is completed, the mixture is heated to 90.degree. C. for 1.5 h, cooled, and filtered with the aid of ethanol. The filtrate is separated and the organic phase is washed with water (100 mL), dried over MgSO.sub.4, filtered, and concentrated. Distillation of the oil at 100-120.degree. C. (0.1 mm Hg) providing the glycidyl ether as an oil.

Preparation of C.sub.12/14 Alkyl-C.sub.9/11 Ether Capped Alcohol Surfactant

Neodol.RTM. 91-8 (20.60 g, 0.0393 mol ethoxylated alcohol available from the Shell chemical Co.) and tin (IV) chloride (0.58 g, 2.23 mmol) are combined in a 250 mL three-necked round-bottomed flask fitted with a condenser, argon inlet, addition funnel, magnetic stirrer and internal temperature probe. The mixture is heated to 60.degree. C. at which point C.sub.12/14 alkyl glycidyl ether (11.00 g, 0.0393 mol) is added dropwise over 15 min. After stirring for 18 h at 60.degree. C., the mixture is cooled to room temperature and dissolved in an equal portion of dichloromethane. The solution is passed through a 1 inch pad of silica gel while eluting with dichloromethane. The filtrate is concentrated by rotary evaporation and then stripped in a kugelrohr oven (100.degree. C., 0.5 mm Hg) to yield the surfactant as an oil.

For more details on these and other suitable nonionic surfactants see U.S. patent Ser. Nos. 60/054,702, 60/054,688 and 60/057,025 all of which are incorporated herein by reference.

Nonionic Ethoxylated/propoxylated Fatty Alcohol Surfactant

The ethoxylated C.sub.6 -C.sub.18 fatty alcohols and C.sub.6 -C.sub.18 mixed ethoxylated/propoxylated fatty alcohols are suitable surfactants for use herein, particularly where water soluble. Preferably the ethoxylated fatty alcohols are the C.sub.10 -C.sub.18 ethoxylated fatty alcohols with a degree of ethoxylation of from 3 to 50, most preferably these are the C.sub.12 -C.sub.18 ethoxylated fatty alcohols with a degree of ethoxylation from 3 to 40. Preferably the mixed ethoxylated/propoxylated fatty alcohols have an alkyl chain length of from 10 to 18 carbon atoms, a degree of ethoxylation of from 3 to 30 and a degree of propoxylation of from 1 to 10.

Nonionic EO/PO Condensates with Propylene Glycol

The condensation products of ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol are suitable for use herein. The hydrophobic portion of these compounds preferably has a molecular weight of from 1500 to 1800 and exhibits water insolubility. Examples of compounds of this type include certain of the commercially-available Pluronic.TM. surfactants, marketed by BASF.

Nonionic EO Condensation Products with Propylene Oxide/ethylene Diamine Adducts

The condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylenediamine are suitable for use herein. The hydrophobic moiety of these products consists of the reaction product of ethylenediamine and excess propylene oxide, and generally has a molecular weight of from 2500 to 3000. Examples of this type of nonionic surfactant include certain of the commercially available Tetronic.TM. compounds, marketed by BASF.

Mixed Nonionic Surfactant System

In a preferred embodiment of the present invention the detergent tablet comprises a mixed nonionic surfactant system comprising at least one low cloud point nonionic surfactant and at least one high cloud point nonionic surfactant.

"Cloud point", as used herein, is a well known property of nonionic surfactants which is the result of the surfactant becoming less soluble with increasing temperature, the temperature at which the appearance of a second phase is observable is referred to as the "cloud point" (See Kirk Othmer's Encyclopedia of Chemical Technology, 3.sup.rd Ed. Vol. 22, pp. 360-379).

As used herein, a "low cloud point" nonionic surfactant is defined as a nonionic surfactant system ingredient having a cloud point of less than 30.degree. C., preferably less than 20.degree. C., and most preferably less than 10.degree. C. Typical low cloud point nonionic surfactants include nonionic alkoxylated surfactants, especially ethoxylates derived from primary alcohol, and polyoxypropylene/polyoxyethylene/polyoxypropylene (PO/EO/PO) reverse block polymers. Also, such low cloud point nonionic surfactants include, for example, ethoxylated-propoxylated alcohol (e.g., Olin Corporation's Poly-Tergent.RTM. SLF18), epoxy-capped poly(oxyalkylated) alcohols (e.g., Olin Corporation's Poly-Tergent.RTM. SLF18B series of nonionics, as described, for example, in WO 94/22800, published Oct. 13, 1994 by Olin Corporation)and the ether-capped poly(oxyalkylated) alcohol surfactants.

Nonionic surfactants can optionally contain propylene oxide in an amount up to 15% by weight. Other preferred nonionic surfactants can be prepared by the processes described in U.S. Pat. No. 4,223,163, issued Sep. 16, 1980, Builloty, incorporated herein by reference.

Low cloud point nonionic surfactants additionally comprise a polyoxyethylene, polyoxypropylene block polymeric compound. Block polyoxyethylene-polyoxypropylene polymeric compounds include those based on ethylene glycol, propylene glycol, glycerol, trimethylolpropane and ethylenediamine as initiator reactive hydrogen compound. Certain of the block polymer surfactant compounds designated PLURONIC.RTM., REVERSED PLURONIC.RTM., and TETRONIC .RTM. by the BASF-Wyandotte Corp., Wyandotte, Mich., are suitable in ADD compositions of the invention. Preferred examples include REVERSED PLURONIC.RTM. 25R2 and TETRONIC.RTM. 702, Such surfactants are typically useful herein as low cloud point nonionic surfactants.

As used herein, a "high cloud point" nonionic surfactant is defined as a nonionic surfactant system ingredient having a cloud point of greater than 40.degree. C., preferably greater than 50.degree. C., and more preferably greater than 60.degree. C. Preferably the nonionic surfactant system comprises an ethoxylated surfactant derived from the reaction of a monohydroxy alcohol or alkylphenol containing from 8 to 20 carbon atoms, with from 6 to 15 moles of ethylene oxide per mole of alcohol or alkyl phenol on an average basis. Such high cloud point nonionic surfactants include, for example, Tergitol 15S9 (supplied by Union Carbide), Rhodasurf TMD 8.5 (supplied by Rhone Poulenc), and Neodol 91-8 (supplied by Shell).

It is also preferred for purposes of the present invention that the high cloud point nonionic surfactant further have a hydrophile-lipophile balance ("HLB"; see Kirk Othmer hereinbefore) value within the range of from 9 to 15, preferably 11 to 15. Such materials include, for example, Tergitol 15S9 (supplied by Union Carbide), Rhodasurf TMD 8.5 (supplied by Rhone Poulenc), and Neodol 91-8 (supplied by Shell).

Another preferred high cloud point nonionic surfactant is derived from a straight or preferably branched chain or secondary fatty alcohol containing from 6 to 20 carbon atoms (C.sub.6 -C.sub.20 alcohol), including secondary alcohols and branched chain primary alcohols. Preferably, high cloud point nonionic surfactants are branched or secondary alcohol ethoxylates, more preferably mixed C9/11 or C11/15 branched alcohol ethoxylates, condensed with an average of from 6 to 15 moles, preferably from 6 to 12 moles, and most preferably from 6 to 9 moles of ethylene oxide per mole of alcohol. Preferably the ethoxylated nonionic surfactant so derived has a narrow ethoxylate distribution relative to the average.

In a preferred embodiment the detergent tablet comprising such a mixed surfactant system also comprises an amount of water-soluble salt to provide conductivity in deionised water measured at 25.degree. C. greater than 3 milli Siemens/cm, preferably greater than 4 milli Siemens/cm, most preferably greater than 4.5 milli Siemens/cm.

In another preferred embodiment the mixed surfactant system dissolves in water having a hardness of 1.246 mmol/L in any suitable cold-fill automatic dishwasher to provide a solution with a surface tension of less than 4 Dynes/cm.sup.2 at less than 45.degree. C., preferably less than 40.degree. C., most preferably less than 35.degree. C.

In another preferred embodiment the high cloud point and low cloud point surfactants of the mixed surfactant system are separated such that one of either the high cloud point or low cloud point surfactants is present in a first matrix and the other is present in a second matrix. For the purposes of the present invention, the first matrix may be a first particulate and the second matrix may be a second particulate. A surfactant may be applied to a particulate by any suitable known method, preferably the surfactant is sprayed onto the particulate. In a preferred aspect the first matrix is the compressed portion and the second matrix is the non-compressed portion of the detergent tablet of the present invention. Preferably the low cloud point surfactant is present in the compressed portion and the high cloud point surfactant is present in the non-compressed portion of the detergent tablet of the present invention.

Branched Alkyl Alkoxylate Surfactants

Also suitable are the branched nonionic surfactants disclosed in co-pending U.S. patent application Ser. No. 60/031,917 which continued as U.S. application Ser. No. 09/170424, now U.S. Pat. No. 6,093,856 all of which is incorporated herein by reference. These branched nonionic surfactants show, some in applications, improved spotting and filming benefits over conventional linear surfactants.

Anionic Surfactant

Essentially any anionic surfactants useful for detersive purposes are suitable. These can include salts (including, for example, sodium, potassium, ammonium, and substituted ammonium salts such as mono-, di- and triethanolamine salts) of the anionic sulfate, sulfonate, carboxylate and sarcosinate surfactants. Anionic sulfate surfactants are preferred.

Nonlimiting examples of surfactants useful herein include the conventional C.sub.11 -C.sub.18 linear or branched alkyl benzene sulfonates and primary, secondary, linear, branched and random alkyl sulfates, the C.sub.10 -C.sub.18 alkyl alkoxy sulfates, the C.sub.10 -C.sub.18 alkyl polyglycosides and their corresponding sulfated polyglycosides, C.sub.12 -C.sub.18 alpha-sulfonated fatty acid esters, C.sub.12 -C.sub.18 alkyl and alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C.sub.12 -C.sub.18 betaines and sulfobetaines ("sultaines"), C.sub.10 -C.sub.18 amine oxides, and the like. Other conventional usefuil surfactants are listed in standard texts. Other anionic surfactants include the isethionates such as the acyl isethionates, N-acyl taurates, fatty acid amides of methyl tauride, alkyl succinates and sulfosuccinates, monoesters of sulfosuccinate (especially saturated and unsaturated C.sub.12 -C.sub.18 monoesters) diesters of sulfosuccinate (especially saturated and unsaturated C.sub.6 -C.sub.14 diesters), N-acyl sarcosinates. Resin acids and hydrogenated resin acids are also suitable, such as rosin, hydrogenated rosin, and resin acids and hydrogenated resin acids present in or derived from tallow oil.

Especially suitable surfactants are the mid-chain branched surfactants. These include, mid-chain branched alkyl sulfates, mid-chain branched alkyl alkoxy sulfates and mid-chain branched alkyl alkoxylates. There are two types of especially preferred branched surfactants they are the sasol type and the shell type. The sasol type surfactants are a surfactant system comprising a branched surfactant mixture, said branched surfactant mixture comprising mid-chain branched and linear surfactant compounds, said linear compounds exceeding at least about 25% and less than about 70%, by weight of the branched surfactant mixture wherein the mid-chain branched surfactant compounds are of the formula:

A.sup.b -B

wherein A.sup.b is a hydrophobic moiety having from about 10 to about 18 total carbons divided between a longest chain and at least one short chain, the longest chain being in the range of from about 9 to about 17 carbon atoms, there being one or more C.sub.1 -C.sub.3 alkyl moieties branching from the longest chain, provided that at least one of the branching alkyl moieties is attached directly to a carbon of the longest linear carbon chain at a position within the range of position 3 carbon, counting from carbon #1 which is attached to the--B moiety, to position .omega.--2 carbon, wherein .omega. is the terminal carbon B is a hydrophilic moiety selected from the group consisting of OSO.sub.3 M, (EO/PO), (EO/PO)mOSO.sub.3 M and mixtures thereof, wherein EO/PO are alkoxy moieties selected from the group consisting of ethoxy, propoxy, and mixtures thereof, wherein m is at least about 1 to about 30 and M is hydrogen or a salt forming cation provided that the average total number of carbon atoms in the A.sup.b moiety in the branched surfactant mixture is within the range of greater than about 11 to about 14.5.

The shell type surfactants surfactant system comprising a branched surfactant mixture, said branched surfactant mixture comprising mid-chain branched and linear surfactant compounds, said linear compounds less than about 25% by weight of the branched surfactant mixture wherein the mid-chain branched surfactant compounds are of the formula:

A.sup.b -B

wherein A.sup.b is a hydrophobic moiety having from about 10 to about 18 total carbons divided between a longest chain and at least one short chain, the longest chain being in the range of from about 9 to about 17 carbon atoms, there being one or more C.sub.1 -C.sub.3 alkyl moieties branching from the longest chain, provided that at least one of the branching alkyl moieties is attached directly to a carbon of the longest linear carbon chain at a position within the range of position 3 carbon, counting from carbon #1 which is attached to the--B moiety, to position .omega.--2 carbon, wherein .omega. is the terminal carbon B is a hydrophilic moiety selected from the group consisting of OSO.sub.3 M, (EO/PO), (EO