NO166724B - STABLE, SHELLABLE, LIQUID DETERGENT COMPOSITION. - Google Patents

Abstract

Liquid detergent compositions suitable for washing clothes, and mainly consisting of water, electrolyte, active ingredient and preferably a builder. They include a space-filling, flock-like surfactant-containing aggregate containing spherulites, substantially co-continuous with an aqueous solution of liquid micelles. They are shear-thinning, mobile, stable to shear stresses, storage under extreme climatic conditions and high pH values.

Description

The present invention relates to stable, pourable, liquid detergent compositions comprising water, surfactant, dissolved electrolyte salt which acts to de-solubilize the surfactant, and suspended particles of a solid builder.

Apart from cases where the opposite is stated, or the context otherwise prohibits it, designations in parentheses, when this is found in the description and requirements, shall have the meaning then attributed to the designation in the definition section.

The term "builder" is used in some cases in its broadest sense to include any non-surfactant which, when present in a detergent composition, increases the cleaning effect of the composition. Generally, however, the term is restricted to the typical "builders" which are primarily useful as a means of preventing or reducing the negative effects that calcium and magnesium ions have on the wash, e.g. by gelation, elimination, precipitation or absorption of the ions, and secondarily as a source of alkalinity and buffering. The term "builder" is used here in a more limited sense, and refers to additives that significantly improve the effects of calcium. They include sodium or potassium orthophosphates, pyrophosphates, metaphosphates or tetraphosphates, as well as phosphonates such as acetodiphosphonates, aminotrismethylenephosphonates and ethylenediaminetetramethylenephosphonates. They also include alkali metal carbonates, zeolites and such organic excipients as salts of nitrile acetic acids, citric acid and ethylenediaminetetraacetic acid, polymeric polycarboxylic acids, such as e.g. polyacrylates and maleic anhydride-based copolymers.

For the avoidance of doubt, "builder" herein includes water-soluble alkali metal silicates, such as sodium silicate, but excludes additives such as carboxymethylcellulose, or polyvinylpyrrolidone, whose function is primarily to suspend dirt or act as an anti-redeposition agent. "Electrolyte" here denotes water-soluble ionic compounds, which have a solubility in water at 0°C, expressed as % by weight of anhydrous compound, of at least 5, which at least partially dissociate in aqueous solution to provide ions, and which at the concentration present, decreases the total solubility (including micellar concentration) of surfactants in such solutions by a "salting out" effect. It includes water-soluble dissociable, inorganic salts such as e.g. alkali metal or ammonium chlorides, nitrates, phosphates, carbonates, silicates, perborates and polyphosphates and also certain water-soluble organic salts which precipitate or "salt out" surfactants. It does not include salts of cations which form water-soluble precipitates with the surfactants present, or which are only slightly soluble in the compositions, such as e.g. calcium chloride or sodium sulfate.

When reference is made here to electrolyte content or concentration, the total amount of dissolved electrolyte is understood to include any dissolved builder, if such builder is also an electrolyte, but excludes any solid substances in the suspension.

"Hydrotrope" here denotes a water-soluble compound that increases the solubility of surfactants in aqueous solutions. Typical hydrotropes include urea • and the alkali metal or ammonium salts of lower alkylbenzene sulfonic acids such as sodium toluenesulfonate and sodium sulfonate.

Whether a particular compound is an electrolyte or a hydrotrope may in some cases depend on the active ingredients present. Sodium chloride is usually considered a typical electrolyte, but in connection with "sultainer" it behaves with a hydrotrope. "Electrolyte" and "hydrotrope", as the terms used here, must therefore be seen in connection with the special active ingredients.

As the term is used herein, "soap" means an at least slightly water-soluble salt of a natural or synthetic aliphatic monocarboxylic acid, which salt has surface-active properties. The term includes sodium, potassium, lithium, ammonium and alkanolamine salts of Cs-22 natural and synthetic fatty acids, including stearic, palmitic, oleic, linoleic, ricinol, behenic and dodecanoic acids, resin acids and branched monocarboxylic acids.

Common "minor ingredients" include ingredients other than water, active ingredients, builders and electrolytes, which may be included in laundry detergent compositions, typically in amounts up to 5%, and which are compatible in the relevant composition with a pourable, chemically stable, non-sedimentary composition. The term includes anti-deposition agents, dispersants, antifoams, perfumes, dyes, optical brighteners, hydrotropes, solvents, buffers, bleaching agents, corrosion inhibitors, antioxidants, preservatives, scale inhibitors, humectants, enzymes and stabilizers for enzymes, bleach activators and the like. The term "functional ingredients" here means ingredients required to provide a beneficial effect in the washing liquid and includes ingredients which contribute to the washing effectiveness of the composition, e.g. surfactants, builders, bleaches, optical brighteners, alkaline buffers, enzymes and anti-deposition agents, and also anti-corrosives and anti-foaming agents, but exclude water, solvents, dyes, perfumes, hydrotropes, sodium chloride, sodium sulfate, co-solvents and stabilizers, if its only function is to give the concentrated composition stability, fluidity and other desired properties. "Payload" means the percentage of functional constituents, based on the total weight of the composition. "Active ingredients" means surface-active materials.

All references to "centrifugation" shall, unless otherwise stated, be assumed to refer to centrifugation at 25°C for 16 hours at 800 times normal gravity.

Any reference to "high G centrifugation" means centrifugation at 20,000 G at 25°C. Unless otherwise stated, high G centrifugation is performed for 5 minutes.

The term "separable phase" here describes components, or mixtures of components of a pourable detergent composition, which are separable from the composition by forming separate layers during centrifugation. Unless the context indicates otherwise, any reference to the composition of separable phases will refer to the composition of those phases separated by centrifugation and reference to the structure of a composition relates to the uncentrifuged composition. A single separable phase may include two or more thermodynamically distinct phases, which cannot be separated from each other by centrifugation, such as e.g. by a stable emulsion or flock.

The term "dispersed" here describes a phase that is discontinuously distributed as separate particles or small droplets in at least one other phase. "Co-continuous" describes two or more interpenetrating phases where each phase extends continuously as a network through a common volume, or is formed by separate or dispersed elements that interact so as to form a continuous matrix that will fix the position of each element in relation to the matrix when the system is at rest. "Intertwined" describes two or more phases which are either co-continuous or where one or more are dispersed in the other(s).

References to "solid phases" are to substances that are actually present in the composition in a solid state at room temperature, and possibly include water of crystal or water of hydration, unless otherwise evident from the context. Reference to solids includes inicrocrystalline and cryptocrystalline solids, i.e. solids where the crystals cannot be directly observed by optical microscopy, but whose presence is evident in other ways. A "solid layer" is a solid, pasty or non-pourable gelatinous layer formed by centrifugation.

"Total water" refers to water present as liquid water in a predominantly aqueous phase, together with any other water in the composition, e.g. water of crystallization or water dissolved or otherwise present in a substantially non-aqueous phase, "Dry weight" refers to weight after drying to constant weight at 140'C.

The term "composition" describes combinations of constituents that make up the dry weight of a composition. That is that the same composition e.g. can constitute a number of compositions that have different percent dry weight,

"Stable" means that no layer containing more than 2% of the total volume separates from the bulk of the composition within 3 months at room temperature under normal gravity.

By "shear test" is meant a test where a sample is passed through a straight 40 mm tube that has an inner radius of 0.25 mm under a pressure of 35.2 kg/cm<2> (manometer pressure). The shear test was in all cases described here, carried out by placing the sample in a 500 ml pressure vessel through a tube with a wide aperture, the tube with a wide aperture was replaced by the tube with a radius of 0.25 mm and a nitrogen pressure of 35.2 kg/cm <2> (manometer pressure) was applied to the pressure vessel until it was empty. The 0.25 mm tube was then replaced by the wide aperture tube so that the cycle could be repeated. This method typically generates shear rates of 127,000 sec."<1>.

"Shear stable" means stable after 3 passes through the shear test, "shear unstable" means unstable after being subjected to 3 or more passes through the shear test, or to a lower shear rate. "Non-shear sensitive" means that the composition does not undergo loss of stability, or significant increase in viscosity after being subjected to moderate shear stress. Shear sensitivity was determined using a "Rheomat 20" viscometer, cone and plate measuring system 2, at 25°C, by increasing the shear load linearly from 0 to 280 sec.-<1> within 1 minute ("Up Sweep") and then immediately reduces it linearly to 0 sec.-<1> il during 1 minute ("Down Sweep"). A composition is considered non-shear sensitive if it is stable after the cycle and if the viscosity at 150 sec--<1> at "Down Sweep" is not more than 10% greater than at "Up Sweep".

"Temperature stable" means that no layer containing more than 5% by volume separates from the bulk of the composition within 24 hours, after being heated by immersing a 4 g sample in a water bath maintained at 90 °C for 110 minutes, followed by immediate immersion in a water bath maintained at 100<*>C for 10 minutes.

When reference is made here to the "pH" of the detergent compositions, the pH measured with a "Pye Unicam 401" combined glass/calomel electrode is understood.

"Conductivity" refers to specific conductance measured at 25'C at a frequency of 50 kHz. The stated results were measured with a "CDM3 Radiometer" conductivity bridge using a "CDC314 flow and pipette cell".

"First conductivity minimum" refers to the curve of conductivity versus increasing dissolved electrolyte concentration in a

liquid detergent composition containing a fixed proportion of active ingredients to water, the conductivity of which usually first increases to a maximum value, then decreases to a minimum value, and then increases again. The designation indicates the concentration of electrolyte corresponding to this minimum value, or the lowest concentration of dissolved electrolyte corresponding to one of a number of such minimum points.

All percentages, unless otherwise indicated, indicate % by weight, based on the total weight of the composition.

All references to "viscosity", unless otherwise stated, are to viscosity measured with a cup and plumb viscometer at 25<*>C after 2 minutes of operation using a flat-bottomed beaker of 20 mm internal diameter, 92 mm high, and a 13.7 mm diameter plumb bob, 44 m long, with tapered ends having a 45<*> horizontal angle, and a 4 mm diameter spindle. The tip of the solder was 23 mm from the bottom of the cup. This corresponds to a "Rheomat 30" viscometer when using a measuring system

C.

"Pourable", as used herein, means a viscosity of less than 2 pascal seconds at a shear rate of 136 sec.-<1>.

"Viscosity drop" means the difference between the viscosity of a shear thinning composition measured at 21 sec-<1> and the viscosity measured at 136 sec-<1>.

"Yield limits" are measured using an "RML Series II Deer Rheometer" at 25"C.

The "Li" phase denotes a clear, liquid, optically isotropic, micellar solution of surfactant in water, which is formed at concentrations of the critical micellar concentration, and where the surfactant molecules are believed to

aggregate so that spherical, oblate (disc) or prolate (rod) micelles are formed.

"Appendix" includes a layer of surfactant which is approx. 2 molecules thick, which is formed from two parallel neighborhoods, each containing surfactants positioned so that the hydrophobic part of the molecules is located in the interior of the leaflet and the hydrophilic part is found on the outer surfaces. "Attachment" is used here to also include interlaced layers that are less than 2 molecules thick. An interlaced layer can be considered an attachment where the two layers have penetrated each other and allows at least some degree of overlap between the hydrophobic parts of the molecules in the two layers.

"Spherulite" means a spherical or spheroidal body having dimensions of from 0.1 to 50 µm. In some cases, spherulites can be deformed into rod, disc, pear or dumbbell shapes. "Vesicle" means a spherulite containing a liquid phase bound by an attachment. "Multiple vesicle" means a vesicle containing one or more small vesicles.

"Lamellar phase" means a hydrated solid, or a liquid crystal phase, in which a large number of appendages are arranged in a substantially parallel row, separated by layers of water or an aqueous solution, and having a sufficiently regular lattice spacing of from 25 to 70 Å, so that it is detectable by neutron diffraction when present in significant amounts in a composition. As the term is used here, it excludes concentric multiple vesicles.

"G" phase refers to a liquid crystal lamellar phase, that type which in the literature is also known as "net" phase or "lamellar" phase. The "G" phase for a given surfactant or mixture of surfactants normally exists in a narrow concentration range. Pure "G" phases can normally be identified by examination of a sample

under a polarizing microscope, between crossed polarizers. Characteristic structures are observed according to the classic article by Rosevear, JAOCS, vol. 31, page 628

(1954) or in J. Colloid and Interfacial Science, vol. 30, No. 4, page 500 (1959).

"Spherical G phase" means multiple vesicles formed from essentially concentric shells of surfactant inclusions alternating with aqueous phase, with a "G" phase space. Typically, conventional G-phases may contain a smaller proportion of spherical G-phases.

"lye" means an aqueous, liquid phase containing electrolyte, where the phase separates from, or is interlaced with, another liquid phase containing more active ingredient or less electrolyte than the lye phase.

"Lamellar composition" means a composition in which the major part of the surfactant is present as a lamellar phase, or in which a lamellar phase is the main factor preventing sedimentation. "Spherulitic composition" means a composition in which the main part of the surfactant is present as spherulites, or which is mainly stabilized against sedimentation by means of a spherulitic surfactant phase.

Liquid detergents have so far been used mainly for milder applications, such as e.g. dishes. The market for powerful detergents, e.g. laundry detergents, have been dominated by powders due to the difficulty in obtaining a sufficient amount of surface-active agent and especially one built into a stable, fiytning composition. Such liquids are theoretically cheaper than powder detergents, because the need for drying is avoided, and in many cases the sulfate filler conventionally used in powder detergents can be replaced with water. They also offer opportunities for greater suitability, and a faster dissolution in the washing water than powder. Attempts to provide solutions of the functional components have been relatively unsuccessful from an economic point of view. One reason for this has been that the most commonly used and most cost-effective builders, e.g. sodium tripolyphosphate are not sufficiently soluble in aqueous compositions. Furthermore, due to the salting out effects, an increase in the amount of dissolved solids will decrease the amount of surfactant that can be dissolved and vice versa. Potassium pyrophosphate builders, along with amine salts of the active ingredients, which are more soluble, have been tried as alternatives to the sodium salts, but have not been found to be cost effective.

Unbuilt liquid detergents containing high concentrations of surfactant have been marketed for laundry use, but are unsuitable for hard water areas and have had little success, being mainly limited to markets where the use of effective builders is subject to legal restrictions, and the competition from powders is consequently less strong.

Another method is to try to suspend the excess of builder as a solid substance in a liquid micellar solution, or emulsion, of the surface-active agent. The problem, however, has been to stabilize the system so that the builder is kept in suspension, and prevent sedimentation. Numerous, relatively sophisticated compositions have been proposed in the literature, including the use of expensive potassium salts instead of cheaper sodium salts, and of co-solvents such as e.g. hydrotropes, dispersants or solvents, all these proposals have been impossible to put into practice because of the higher price. Even with such additional additives, it was considered necessary to use relatively low concentrations of solid builder, this gives limited washing efficiency. This method has been conditioned by certain assumptions: that the active ingredient should be present in solution as far as possible; that the amount of active ingredient should be relatively high; that the amount of suspended solids should be as small as possible to avoid problems in stabilizing the suspension against sedimentation; that special thickeners or stabilizers were essential to prevent sedimentation, and that electrolytes which would precipitate the surfactants should be avoided or kept at very low concentrations.

A main feature of the prior art has been its empirical nature. No acceptable, general theory has been proposed that can explain the stability of some compositions, and the instability of others. Consequently, there is no possibility of predicting which compositions will be stable, and no general method for designing new, stable, liquid detergents. The technique contains no generally applicable description, and even specific examples in the prior patents relating to liquid detergents provide compositions that separate within a few weeks. The relatively few exceptions have apparently been discovered by chance and no extrapolation has been possible.

Products of this type have been introduced commercially in Europe and Australia, but have been associated with certain serious deficiencies. The products have had relatively poor washing performance, either due to a low weight ratio between builders and active ingredients, or due to low alkalinity. They have also shown signs of unwanted sensitivity to mechanical and/or thermal stress, e.g. during shear loading or storage under extreme climatic temperature conditions. That is some compositions separate under shear stress, others become very viscous, most separate after storage at either 0 or 40°C. Prior art, however, contains no description of how to avoid the aforementioned disadvantages.

In addition to the compositions that have been developed commercially, many compositions have been proposed in the literature which in practice have not been suitable for commercial exploitation. Typically, such compositions may be unstable, or insufficiently stable to withstand normal storage without undergoing sedimentation, or they may be too expensive to manufacture compared to the washing effect that can be achieved to be considered suitable for commercial development.

Recently, a series of compositions has been proposed in which the active ingredients form a network of a lamellar phase, which is separable from the aqueous phase by centrifugation, which provides a gel structure capable of supporting the suspended particles of solid build . The gel structure is achieved by adding sufficient electrolyte to salt out the active ingredient, so that an aqueous lye phase and a separable lamellar phase are formed, and by keeping the solids content above a threshold for stability and below a ceiling for pourability. The amount of electrolyte required depends on how hydrophilic the surfactant is and on its melting point, and whether other dissolution aids, such as e.g. hydrotropes or solvents, are present. The previously mentioned gel compositions have a higher payload in the ratio between builder/active ingredient, and are more cost-effective than known commercial liquid compositions. The best of the previously mentioned lamellar gel compositions is a more cost-effective soil remover than the best laundry powders.

However, the lamellar compositions that have been described so far show a mobility that is lower than optimal for some purposes.

A new group of compositions including electrolyte, active ingredients and water has now been discovered, which are capable of suspending solid matter, such as e.g. builders, so that stable compositions are formed that combine improved washability with satisfactory mobility. It is believed that the stability of the new compositions is due to a hitherto undescribed spherulitic structure, and a general method for the production of stable, mobile compositions with superior detergency, from a wide range of different active ingredients, has been discovered.

Preferred embodiments of the present invention show at least some of the following advantages compared to products hitherto marketed: high useful weight; high ratio of builder to surfactant; improved stability; lower price due to cheaper components and easier manufacturing; high mobility; improved washability; high pH and/or alkalinity; good stability at high and/or low storage temperatures; and satisfactory behavior under shear loading.

It has been discovered that when active ingredients, dissolved electrolyte and water are present in certain proportions, which depend on the particular active ingredients and electrolytes chosen, a stable spherulitic composition is obtained which is capable of suspending solid particles, such as e.g. builds. It has been discovered how such compositions can be obtained, and how they can be identified by means of a number of physical properties. It has also been discovered how to optimize the proportions of active ingredients and electrolyte in order to achieve compositions which are stable against shear stresses, and the variations in temperature which are likely to be encountered during storage in widely different climates; and against high pH or alkalinity, and which are highly mobile. In contrast to compositions exemplified in the prior art regarding lamellar compositions, the new compositions appear to be stabilized by surfactants present in a spherulitic, rather than a lamellar, phase.

Prior art relating to liquid detergents is very voluminous. For the purpose of the present invention, however, one can disregard the numerous references to powerful, liquid detergents and to unbuilt or built-up, clear, liquid laundry detergents where all the ingredients are present in solution. The concentration of buildings is significantly below the desired level.

Later general summaries of the state of the art include JAOCS (April 1981) page 356A - "Heavy Duty Laundry Detergents" which includes an overview of the typical commercially available liquid compositions, and "Recent Changes in Laundry Detergents" by Rutkowski, published in 1981 by Marcel Dekker Inc. in the "Surfactant Science Series".

The three main approaches to solving the problem of formulation of fully built liquid detergents have been to emulsify a surfactant in an aqueous solution of builder, and to suspend a solid builder in an aqueous solution or emulsion of surfactant and to suspend solid builder in a gel containing a lamellar matrix of surfactant.

Examples of the first method are US patents

3,235,505, US-PS 3,346,503, US-PS 3,351,557, US-PS 3,509,059, US-PS 3,574,122, US-PS 3,328,309 and Canadian Patent 917,031.

In each of these patents, an aqueous solution of a water-soluble builder is sufficiently concentrated to salt out the surfactant (usually of the liquid, non-ionic type) and the latter is dispersed in the aqueous medium as colloidal droplets, by means of various emulsifiers. In each case, the system is a clear emulsion, which generally contains relatively low concentrations of builders, and if is undesirably expensive because of the price of the soluble builders used.

Examples of the second method are given by GB patent v 855 893, GB patent 948 617, GB patent 943 271, GB patent 1 468 181, GB patent 1 506 427, GB patent 2 028 365, European patent 38,101, Australian Patent 522,983, US-PS 4,018,720, US-PS 3,232,878, US-PS 3,075,922 and US-PS 2,920,045. The compositions described in these patents are either not stable or are not temperature stable, or are not shear stable. Commercial products corresponding to two examples in two of these patents have recently been marketed in Australia and Europe. In particular, a composition corresponding to Australian patent 522 983 has achieved some commercial success, but is shear sensitive.

The third method is described in European patent publication 0 086 614. The compositions described show a matrix of lamellar, solid or liquid crystalline surfactant. Such compositions may have higher viscosities than desired for certain applications.

Another method is to suspend solid particles in an anhydrous, liquid non-ionic surfactant, see e.g. Belgian patent 1 600 981. Such systems are expensive, restrictive with regard to the choice of surfactant and provide unsatisfactory cleaning properties. The concentration of building materials, although high in relation to the total composition, is low in terms of active ingredients, and the cost efficiency is therefore very low.

Several patents describe the emulsion where the builder is in the dispersed phase of an emulsion, rather than in suspension. US-PS 4,057,506 describes the preparation of clear emulsions of sodium tripolyphosphate, and US-PS 4,107,067 describes inverse emulsions where an aqueous solution of builder is dispersed in a liquid crystal surfactant system.

Reference can also be made to numerous patents relating to cleaning agents for hard surfaces, where an abrasive is suspended, usually in an aqueous solution of surfactant, see e.g. GB Patent 2,031,455, US-PS 3,281,367, US-PS 3,813,349, US-PS 3,956,158 and US-PS

4,302,347. Generally, however, the low concentrations of surfactant, the absence of builder, and the presence of high concentrations of emollient will generally prevent these patents from being useful in the formulation of laundry detergents.

Other publications of possible interest are: Australian patent 507 431, which describes suspensions of barley in aqueous surfactants, stabilized with sodium carboxymethyl cellulose or clay as a thickener. However, the concentrations of functional components, and especially of builders, in the exemplary compositions, are not sufficient to provide an acceptable, commercial product and the stability is not good enough to provide useful storage times.

US-PS 3,039,971 describes a detergent paste containing the builder in solution.

French patent 2,283,951 describes suspensions of zeolite builders in nonionic surfactant systems: however, the compositions are rigid pastes and not mobile liquids.

US-PS 3,346,504 and US-PS 3,346,873 describe dissolution of "sultainer" with hydrotropes, which in the patent documents are referred to as "electrolytes".

A.C.S, Symposium Series No. 194 "Silicates in Detergents" describes the effect of silicates on liquid detergents.

It should be noted that each of the foregoing patent references was selected from the very extensive selection, and relevant aspects were elucidated by hindsight, using the knowledge upon which the present invention is based at the time of selection. The average person skilled in the art at the time of the first claimed priority, and without previous knowledge of the present invention, would not necessarily have selected the patents as particularly significant or the aspects as particularly interesting or relevant.

The foregoing summary therefore does not represent a complete picture of prior art.

According to the present invention, a stable, pourable, liquid detergent composition is provided which comprises water, surfactant, dissolved electrolyte salt which acts to de-solubilize the surfactant, and suspended particles of a solid builder, whereby the total weight ratio of the builder when any dissolved builder is included, to the surfactant is greater than 1.5:1, and in which composition the surfactant's weight ratio to the water is such that when said salt is continuously dissolved in said surfactant, in the aqueous micelle solution where said weight ratio prevails, the curve for the solution's electrical conductivity as a function of the salt concentration through a wave valley region, containing a minimum for electrical conductivity, at which the solution is stable and cloudy. The composition is characterized by the fact that of said salt, when a possibly dissolved build-up is taken into account, a total amount corresponding to the said wave valley area is dissolved in said composition, which amount is chosen between the minimum and maximum amounts at which the composition is stable for at least 3 months both at room temperature and at a temperature of 5°C, e.g. at 0°C, and preferably also at 40°C.

Preferably, the pour point of the composition is greater than 1.5, more preferably greater than 2, most preferably greater than 2.5, i.e. greater than 3, and preferably less than 10 dyne cm-<2>. Preferably, the viscosity at 136 sec.-<1> is less than 1.5, more preferably less than 1, ie from 0.2 to 0.6 pascal seconds.

The composition may also contain ordinary minor components. Preferably, the active ingredients are present in amounts of from 10 to 20% by weight, more preferably 10 to 14% by weight, and the total weight ratio of builder to active ingredients is greater than 1.5:1.

In more detail, the present invention provides stable pourable liquid detergent compositions comprising water, active ingredients and electrolyte, all compositions exhibiting at least some, but not necessarily all, of the following properties: they provide a spherulitic phase interlaced with a base or L^- phase and preferably co-continuous with the base or the I^ phase; they are mainly non-lamellar; they include a floc system which is preferably space-filling, they include a floc system which is formed from particles which include the active ingredients which are preferably spherulites containing surfactants, which typically have concentric shells of surfactant alternating with an aqueous one, e.g. base, phase, and having a repeating distance of from 60 to 100 Å, preferably 70 to 90 Å, often 75 to 85, e.g. 80 Å; they include spherulites of from 0.5 to 5 µm, preferably 0.6 to 5 µm in diameter, exhibiting so-called "Maltese cross" structure when viewed at suitable magnification between crossed polarizers; they are shear thinning; they have a viscosity drop greater than 0.35, usually greater than 0.4, often greater than 0.45 pascal seconds, but preferably less than 2 pascal seconds, e.g. 0.475 to 1.5, especially 0.48 to 1.1 pascal seconds; they have a high useful weight of functional components, typically greater than 20% by weight, e.g. 25-75%, more usually at least 30%, preferably at least 35, more preferably at least 40% by weight; they contain a high ratio of builders to active ingredients, e.g. greater than 1:1, preferably 1.2:1 to 4:1, more preferably 1.4:1 to 4:1, most preferably 1.5:1 to 3.5:1; they contain more than 5, and preferably more than 8% by weight of active ingredients; they contain less than 25%, preferably less than 20%, usually less than 15%, more preferably less than 14.5%, most preferably less than 15%, i.e. from 10 to 13.5% by weight of the composition of active constituents; they form a single, aqueous layer, and a solid layer upon centrifugation where the aqueous layer usually has a pour point of less than 1, preferably at least 1.5 dyne cm-<2>, e.g. 2 to 10 dynes cm-<2> and typically a viscosity of less than 1.5 pascal seconds at 135 sec.-<1>; the weight fraction of active ingredients in the mainly aqueous layer which is formed after centrifugation, based on the total amount of active ingredients in the composition is greater than 50%, preferably greater than 55%, greater than 60%, but is less than 90%, preferably less than 85%, e.g. less than 80%, such as 75 to 65%; no clear base layer is observed at high G centrifugation for 90 minutes; The pH of the composition is greater than 8.5, preferably 9 to 13, e.g. 9.5 to 12; the composition gives a washing liquid when diluted with water to 0.5% dry weight which has a pH greater than 9.7, preferably greater than 10, e.g. 10.9 to 11.1; the alkalinity is sufficient to require less than 0.8 ml of N/10 HC1 to reduce the pH of 100 ml of wash liquor at 0.5% dry weight to 9, preferably 1 ml, e.g. 4.7 to 8.6 ml; at least one substantially aqueous liquid phase contains sufficient electrolyte to provide a concentration of at least 0.3, preferably at least 0.5, more preferably at least 1.2, e.g. 2.0 to 4.5 g of ions per liters of total alkali metal and/or ammonium cations; the concentration of the electrolyte is greater than that corresponding to the first conductivity minimum on the curve of the conductivity as a function of the electrolyte concentration; the conductivity is not more than 2 mS greater than the conductivity at a first conductivity minimum; the concentration of electrolyte is less than the amount which causes the formation of a significant proportion of lamellar phase; the electrolyte concentration is above the minimum which provides a stable, and preferably above the minimum which provides a shear stable, composition; the composition is non-shear sensitive; the composition is temperature stable; the composition is stable at 40* C; the conductivity of the composition is below 15 milliSiemens per cm; the composition contains at least 15% by weight, preferably more than 20% by weight of builder; the builder is at least predominantly sodium tripolyphosphate; the builder includes alkali metal silicate and/or carbonate, preferably sodium silicate and/or sodium carbonate; the viscosity of the composition at a shear rate of 136 sec.-<1> is between 0.1 and 2 pascal seconds, preferably between 0.2 and 1 pascal seconds, e.g. 0.3 to 0.6 pascal seconds; the composition preferably has a pour point of at least 1, more preferably at least 1.5, e.g. at least 2, preferably less than 30, e.g. less than 20, most preferably less than 15, usually less than 10 dyne/cm<2>; a build-containing phase includes solid particles having a maximum particle size below the limit at which the particles will settle; the composition is shear stable.

The active ingredients include at least two components, one of which is a non-ethoxylated anionic surfactant and the other is a surfactant that forms stable foams, such as an ether sulfate, alkanolamide or amine oxide.

When the concentration of dissolved electrolyte in a suitable aqueous mixture of surfactants is gradually increased from 0, the composition will typically pass through a series of easily recognizable steps, as follows.

Stage I

First, the conductivity increases to a maximum, during this step the viscosity increases and the initially clear, optically isotropic I^ phase begins to show signs of the formation of spherulites. The latter are visible under the microscope and show so-called "Maltese cross" structure, which is normally associated with spherulitic "G" phase, when viewed under crossed polarizers. However, neutron diffraction shows no evidence of a "G" phase or any other liquid crystal phase, and is consistent with a predominantly micellar composition. The compositions in stages are generally clear and stable, but have no ability to suspend solid particles.

Step IJ,

In the second step, the conductivity falls with increasing electrolyte concentration, and the composition becomes unclear. High "GM<->centrifugation separates the composition into a clear, aqueous phase, and an opaque "emulsion phase", the volume fraction of the latter phase increases with increasing electrolyte concentration. Under the microscope, the spherulites are observed to increase in number and decrease in size, and to aggregate into loose flocs separated by optically isotropic regions, where the flocs become denser as the electrolyte concentration increases.

Neutron diffraction studies are consistent with reduced micellar concentrations and an increasing proportion of larger bodies, but not with the presence of significant proportions of the "G" phase. The compositions in stage II are cloudy and unstable and settle quickly.

Stage III

The conductivity drops to a minimum and then begins to increase. The voids between the spherulite flocks disappear and the spherulites form a space-filling flock that extends through the liquid phase. High G centrifugation does not separate an aqueous phase, even when continued for 90 minutes. A pour point is observed, which increases to a maximum, and the composition becomes shear-thinning with a marked drop in viscosity.

Neutron diffraction provides no evidence of significant proportions of lamellar phase. Nuclear magnetic resonance similarly provides no evidence of significant amounts of "G" phase and indicates a low concentration of micellar surfactants. Electron microscopy indicates that at least some of the spherulites are multiple vesicles with a predominantly concentric arrangement of shells or overlapping partial shells, possibly with a somewhat greater spacing than in a normal "G" phase.

Stage III compositions are stable and capable of suspending solid particles to form a stable suspension. Such step III compositions constitute the present invention.

Stage IV

Further addition of dissolved electrolyte causes a stepwise reduction in the size of the spherulites, and an intensification in the brightness of the "Maltese cross" structure. The spherulites cease to be space-filling, and form separate flocks, separated by optically isotropic regions. The pour point and viscosity drop decrease and the conductivity increases to a maximum and begins to level off. Neutron diffraction provides evidence for significant amounts of "G" phase. High G centrifugation separates a clear base phase from a cloudy layer. The composition is unstable, shows a tendency to sedimentation and is unable to settle solid particles.

Step V

They form a lamellar composition of the type described in European patent 0 086 614. The viscosity is relatively high when the water content is set at the level required to achieve a stable composition.

The aforementioned sequence is typical of the interaction between electrolytes and a large amount of aqueous mixtures of surfactants. Where the composition already contains some dissolved electrolyte, such as e.g. in formulated detergents containing suspended tripolyphosphate, or in cases where the original surfactant mixture is not fully soluble in water, the first stage may not be observed. Correspondingly in cases where the solubility of the electrolyte is limited, such as e.g. in the case of sodium tripolyphosphate or sodium carbonate, addition of additional electrolyte beyond the saturation limit will not advance the composition to the further steps.

Preferred compositions are within the third step of the above sequence. Between the third stage and the second and fourth stages, respectively, there exist intermediate compositions which are semi-stable. Such compositions show a flock of surface-active spherulites, which are not completely space-filling, this can be determined by the fact that high G centrifugation still for 90 minutes results in the formation of a clear, aqueous layer, or where the spherulites are able to irreversibly break down . Such compositions, although they can be stable when allowed to stand at room temperature, are often unstable when exposed to different types of stresses, such as e.g. high shear stresses, increased or decreased temperatures or pH changes. Their ability to suspend particulate solids is often limited,

a number of previously proposed compositions lie in these semi-stable regions.

It has been discovered that the compositions that lie within these semi-stable "borderline" regions can generally be modified according to the description in the present application, by adjusting the electrolyte content so that they are brought closer to the stable regions of stage III.

Typically, upon centrifugation, the stage III compositions will separate into an aqueous layer containing electrolyte and from 90 to 50% by weight of the total amount of active ingredients, typically 80% to 50%, more commonly 75% to 55%, e.g. e.g. 70% to 55% of the total amount of active ingredients, and at least one other layer, where this second layer preferably contains from 15% to 50% by weight of the total amount of active ingredients together with a significant proportion of the builder. The viscosities for the compositions according to the invention, at a shear rate of 136 sec.-<1>, are typically between 0.1 and 2, preferably 0.2

and 1.5, e.g. 0.25 and 0.6 pascal seconds, and viscosity

the drop is typically between 0.4 and 2, e.g. 0.45 to 1.5 pascal seconds.

The Stage III compositions are non-shear sensitive and usually shear stable. High shear forces will often make the semi-stable boundary compositions unstable. Viscosity usually increases significantly even at moderate shear forces and they can then undergo rapid sedimentation. This can cause practical difficulties during the manufacture and filling of bottles. Stage III compositions of the present invention are generally stable at high pH, and when stored at temperatures around 40<*>C or below 5"C" unlike many semi-stable compositions. They are typically temperature stable when heated to 100' C.

Stage III compositions typically show no evidence of a lamellar phase by neutron diffraction analysis, although some compositions near the stage IV boundary may show evidence of minor amounts of "C" phase.

It is assumed that the aforementioned behavior can be most easily explained by the assumption that the surfactant is gradually transferred from the micellar to a spherulitic phase with increasing electrolyte concentration. It is believed that the spherulite initially takes the form of multiple vesicles, where a greater number of appendages are arranged approximately concentrically, but with a larger and more irregular spacing than in a conventional "G" phase.

It is possible that two aqueous phases exist, an L^ phase and a base phase, where the latter phase can also be an I^ phase containing fewer micelles and more electrolyte than the former. One of these phases, possibly the base phase, may constitute the inner phase of the vesicles.

It has been found that by increasing the electrolyte content and reducing the proportions of active ingredients it is possible to provide compositions which are less viscous with equivalent stability and fixed useful weight. It is believed that this reduces the proportion of micellar surfactants without significantly reducing the amount of spherulites. The lower content of micelles reduces the viscosity, while the content of the spherulite phase remains sufficient to maintain stability.

It is assumed that in the stable composition according to the invention the spherulites are sufficiently densely packed to form an aggregated flock which is essentially space-filling, i.e. extends through the volume of the liquid. The spherulites probably interact so that a weak 3-dimensional matrix is formed that is strong enough to support the suspended particles, but weak enough to break down and flow under the influence of shear forces, and to recover when these are withdrawn. The size of the spherulites seems to correlate with the stability, compositions with large spherulites of 5 pm and more are less stable than those where the majority of the surfactant is in the form of spherulites of from 0.5 to 5 pm.

As the electrolyte content increases, the spherulites become smaller and possibly more compact, tending toward the tighter, more regularly spaced, spherical "G" phase. As a result, the "G" phase spherulites are no longer space-filling, and the composition shows a tendency towards sedimentation.

The compositions preferably contain at least 5%, less than 30%, and generally less than 25% by weight of surfactants. More preferably, the surfactants comprise from 5 to 20% by weight of the composition, e.g. 8-15% by weight, typically 10 to 14.5% by weight, particularly preferably less than 14, often less than 13%.

The concentration of active ingredients can be a critical factor in obtaining the compositions according to the present invention. Below a certain minimum which varies according to the particular active system, the composition cannot be stabilized by adding more electrolyte, however, the maximum value is also important to avoid highly viscous compositions.

Previously known semi-stable spherulitic compositions have often contained relatively large amounts of active ingredients. This has resulted in a relatively high viscosity for the aqueous suspension medium, which in turn has greatly limited the amount of build that could be suspended for a given acceptable limit of viscosity. This means that the total ratio between building materials and active ingredients has been low compared to powders, with the consequent poor washing ability.

It was very unexpected that the amount of active ingredients in such compositions could be reduced without the system being totally destabilized. It was surprisingly discovered that if the electrolyte concentration is raised sufficiently, the concentration of active ingredients can be significantly reduced, so that aqueous media of equivalent or even greater stability, which have lower viscosity, are provided. Such media can suspend larger quantities of builders without losing the desired mobility, and the resulting large increase in the ratio of builders to active ingredients provides a correspondingly significant increase in cost efficiency.

In general, it is considerably easier to produce spherulitic flocks from mixed surfactants than from individual surfactants. This means that mixtures of one or more non-ethoxylated, anionic surfactants such as e.g. alkylbenzene sulphonate and/or alkyl sulphate, with one or more co-surfactants which form stable foams, such as e.g. alkyl ether sulfates and/or alkanolamides or amine oxides, are generally more suitable than either of these surfactants alone. Smaller amounts of ethoxylated, non-ionic surfactants or of amphoteric surfactants, or cationic fabric softeners may also be present.

The mixture of surfactants can e.g. include one or more at least partially water-soluble salts of sulfonic or mono-esterified sulfuric acids, e.g. alkyl benzene sulfonate, alkyl sulfate, alkyl ether sulfate, olefin sulfonate, alkane sulfonate, alkyl phenyl sulfate, alkyl phenol ether sulfate, alkyl ethanol amide sulfate, alkyl ethanol amide ether sulfate, or alpha-sulfo fatty acid, and its esters, each having at least one alkyl or alkenyl group of from 8 to 22, more commonly 10 to 20, aliphatic carbon atoms. Said alkyl or alkenyl groups are preferably straight-chain primary groups, but may optionally be secondary or branched groups. The term "ether" above refers to polyoxyethylene, polyoxypropylene, glyceryl and mixed polyoxyethylene-oxypropylene or mixed glyceryloxyethylene or glyceryloxypropylene groups, typically containing from 1 to 20 oxyalkylene groups. For example the sulfonated or sulfated surfactant can be sodium dodecylbenzenesulfonate, potassium hexadecylbenzenesulfonate, sodium dodecyldimethylbenzenesulfonate, sodium lauryl sulfate, sodium tallow sulfate, potassium oleyl sulfate, ammonium lauryl mono-ethoxysulfate or mono-ethanolamine phetyl 10 mol ethoxylate sulfate.

Other anionic surfactants useful in the present invention include paraffin sulfonates, olefin sulfonates, fatty alkyl sulfosuccinates, fatty alkyl ether sulfosuccinates, fatty alkyl sulfosuccinates, fatty alkyl ether sulfosuccinates, acyl sarcosinates, acyl taurides, isethionates, soaps such as stearates, palmitates, resinates, oleates, linoleates and alkyl ether carboxylates. Anionic phosphate esters can also be used. In each case, the anionic surfactant typically contains at least one aliphatic hydrocarbon chain having from 8 to 22, preferably 10 to 20 carbon atoms, and, in the case of ethers, one or more glyceryl and/or up to 20 ethyleneoxy and/or propyleneoxy groups.

Preferred anionic surfactants are sodium salts. Other salts of commercial interest include salts of potassium, lithium, calcium, magnesium, ammonium, monoethanolamine, diethanolamine, triethanolamine and alkylamines containing up to 7 aliphatic carbon atoms.

The mixture of surface-active agents may optionally contain or, less preferably, consist of non-ionic surface-active agents. The non-ionic surfactant can e.g. be a Ci<g_>22-alkanolamide of a mono- or di-lower alkanolamine such as e.g. coconut monoethanolamide. Other nonionic surfactants that may optionally be present include ethoxylated alcohols, ethoxylated carboxylic acids, ethoxylated amines, ethoxylated alkylol amides, ethoxylated allylphenols, ethoxylated glyceryl esters, ethoxylated sorbitan esters, ethoxylated phosphate esters, and depropoxylated or ethoxylated and propoxylated analogs of all of the foregoing said ethoxylated nonionic substance, all of which have a C8_22"alJcy1~ or alkenyl group, and up to 20 ethyleneoxy and/or propyleneoxy groups, or any other nonionic surfactant, which has heretofore been incorporated into powdered or liquid detergent compositions, e.g. amine oxides. The latter typically have at least one O3-22"» preferably C10-20~alkyl~ or alkenyl groups, and up to "two lower (e.g. C1-4, preferably ) alkyl groups.

The preferred active ingredients or mixtures are e.g. those having an HLB greater than 7, preferably greater than 8, more preferably greater than 10, most preferably greater than 12 and preferably less than 18, more preferably less than 16, most preferably less than 15.

Some of the detergents may contain cationic surfactants, and in particular cationic fabric softeners and/or bactericides, usually as a minor proportion of the total active material. Cationic plasticizers of importance in the present invention include quaternary amines having two long chain (e.g. <C>^-22 » typically C16_2u) alkyl or alkenyl groups, and either two short chain (e.g. cj_4) alkyl groups , or a short chain, and a benzyl group. They also include imidazolines and quaternized imidazolines having two long-chain alkyl or alkenyl groups, and amidoamines and quaternized amidoamines having two long-chain alkyl or alkenyl groups. The quaternized plasticizers are all usually salts of anions which give a certain water solubility such as e.g. formate, acetate, lactate, tartrate, chloride, methosulfate, ethosulfate, sulfate or nitrate. Compositions according to the invention which have a textile softening character can contain smectite clays.

Compositions according to the invention may also contain amphoteric surfactants, these may typically be included in surfactants such as hiar cationic fabric softeners, but may also be included in any of the other detergent types discussed above, usually as a minor component of the active ingredients.

Amphoteric surfactants include betaines, sulfobetaines and phosphabataines formed by reaction between a suitable tertiary nitrogen compound having a long straight chain alkyl or alkenyl group and a suitable reagent, such as chloroacetic acid or propane "sulton".

Examples of suitable tertiary nitrogen-containing compounds include: tertiary amines having one or two long straight chain alkyl or alkenyl groups, optionally a benzyl group and any other substituted short chain alkyl group; imidazolines having one or two long straight chain alkyl or alkenyl groups, and amidoamines having one or two long straight chain alkyl or alkenyl groups.

It will be clear to those skilled in the art that any surfactant capable of performing a useful function in the wash liquor can. included. A more detailed description of the main types of surfactants commercially available is given in the latest edition of "McCutcheon's Emulsifiers & Detergents", published by the McCutcheon division of the Manufacturing Confectioners Publishing Company.

The electrolyte is essential because it must interact with the surfactant, so that they form a spherulitic system. However, the electrolyte concentration is preferably not high enough to allow significant stacking of any planar inclusions, so that non-spherical lamellar phases are formed. Such lamellar phases can provide unstable or shear-unstable compositions, unless the useful weight is sufficiently, high, so that the lamellar phase forms a stable structure according to European patent 0 086 614A. The relatively strong matrix that characterizes the latter composition, however, generally leads to an undesirably high viscosity. For a suitable system of surfactant, at a suitable concentration, it has been found that it is possible to stabilize the system by including in the composition a suitable amount of electrolyte.

An insufficient amount of electrolyte leads to unstable, or shear- or temperature-sensitive systems, and/or systems that have an undesirably high viscosity. The proportion of electrolyte must therefore be chosen according to the properties of the surfactant and the amount of any hydrotrope present in order to provide compositions according to the present invention.

The optimum proportion of electrolyte can generally be determined by making stepwise additions of electrolyte to an aqueous, micellar solution of the active ingredients (typically 15-20% by weight active ingredients), and observing one or more characteristic properties of the system such as turbidity, conductivity, pour point, appearance under a polarizing microscope or behavior in high G centrifugation.

When the characteristics characteristic of stage III as described above are detected, e.g. a turbid composition at, or near, a first conductivity minimum, with a flock of spherulites that do not show clear isotropic areas, and that do not show a clear layer on high G centrifugation, the spherulitic area has been identified.

The proportion can be optimized within this range by observing the amount required for no clear layer to be obtained at high G centrifugation for 90 minutes. If the composition is intended for a market where low viscosity is more important than e.g. good storage stability at low temperature, the optimized composition can be gradually diluted until a suitable viscosity is achieved or until signs of instability are observed. If the latter occurs, further additions of electrolyte can be made until a sufficiently stable composition is achieved.

The amount of electrolyte is preferably greater than the amount at the first conductivity minimum in the conductivity/electrolyte concentration curve, and corresponds to the amount required to provide a yield strength greater than 1.5 dyne cm-2.

It is preferred to use functional electrolytes, such as e.g. carbonates, silicates, pyrophosphates, polyphosphates, nitriloacetates and citrates, all of which are builders, but the effective concentration of some such electrolytes, e.g. carbonates, can be undesirably limited by solubility. In such cases, it may be necessary to add a more soluble non-functional electrolyte. Sodium chloride and sodium nitrate have been found to be particularly effective in this regard.

Often the amount of electrolyte, in at least one mainly aqueous phase, is sufficient to provide a concentration of at least 0.3, preferably at least 1.2, e.g. 2.0 to 4.5, gram ions per liter of alkali metal, alkaline earth metal and/or ammonium cations.

The builders are believed to be present, at least in part, as discrete, solid crystallites, suspended in the composition. The crystallites typically have a size of up to 60, e.g. in to 50 pm.

It has been found that compositions containing sodium tripolyphosphate as a builder, or at least a greater proportion of sodium tripolyphosphate in admixture with other builders, exhibit stability and mobility over a greater range of dry weight than corresponding compositions with other builders. Such compositions are therefore preferred. However, the present invention also includes compositions that include other builders, such as e.g. potassium tripolyphosphate, carbonates, zeolites, aitryl triacetates, citrates, metaphosphates, pyrophosphates, phosphonates, EDTA and/or polycarboxylates, optionally, but preferably, in admixture with tripolyphosphate. Orthophosphates may be present, preferably as minor components in admixture with tripolyphosphate, in the same way as alkali metal silicates and carbonates.

Silicates and carbonates are particularly preferred since they perform several valuable functions. They provide the free alkalinity desired to saponify fatty substances in the dirt, they have a builder effect and, in the case of silicates, they inhibit corrosion of aluminum surfaces in washing machines. In addition, they are effective as electrolytes necessary to form a spherulitic system.

Where silicates are used to produce compositions according to the invention, one typically has a Na 2 O : SiO 2 ratio of from 1:1 to 1:2, or 1:1.5 to 1:1.8. It should be noted, however, that any ratio of Na 2 O (or other base) to SiO 2 , or even silicic acid, may be used to provide silicate in the composition, and any necessary additional alkalinity may be provided by the addition of another base like for example. sodium carbonate or -hydroxide. Formulations not to be used in washing machines do not require silicates, provided there is an alternative source of alkalinity.

Compositions where the builder is present, so to speak, exclusively in solution, are not excluded, e.g. sodium nitrilotriacetate, sodium citrate, sodium silicate or mixtures thereof.

The builder normally makes up at least 15% by weight of the compositions, preferably at least 20%. It is preferred that the ratio between builder and surfactant is greater than 1:1, preferably 1.2:1 to 4:1.

For economic reasons, it is generally preferred that the cations present be, at least predominantly, sodium. E.g. is the preferred builder sodium tripolyphosphate, the preferred anionic surfactants are sodium salts of sulfated or sulfonated anionic surfactants, and any anti-redeposition agents, e.g. carboxymethylcellulose, or alkali, e.g. silicate or carbonate, are also preferably present as sodium salts. Sodium chloride, sodium nitrate or other soluble inorganic sodium salts can be added to increase the electrolyte concentration. Calcium is normally only present when the active ingredients include surfactants, such as e.g. olefin sulfonates or nonionic compounds that can tolerate its presence. Magnesium salts may be present, and are more compatible with surfactants than calcium. It is alternatively possible, but less preferred, to select salts of potassium, ammonium, lower amines, alkanol-amines or mixed cations. However, it is unlikely that compositions containing large amounts of such cations are cost effective compared to conventional laundry powders.

The compositions according to the invention are preferably alkaline, in that they are preferably buffered with an alkaline buffer, so that a pH is provided in the composition, measured with a glass calomel electrode, above 8.5, preferably above 9, most preferably above 9.2 , e.g. 9.5-12, especially 10-11. It is particularly preferred that the compositions are designed so that they provide a pH greater than 9.7, e.g. greater than 10, especially 10.5 to 11.5, in a washing liquid containing the composition diluted to 0.5% dry weight. It is desirable that they have sufficient free alkalinity to require at least 0.4 ml, preferably at least 0.8 ml, most preferably 1 to 12 ml, e.g. 3 to 10 ml, typically 4 to 9 ml, of N/10 HCl to reduce the pH of 100 ml of a dilute solution of the composition, containing 0.5% dry weight, to 9, although compositions having higher alkalinity may also be commercially acceptable. In general, lower alkalinity is less commercially acceptable.

The alkaline buffer is preferably sodium tripolyphosphate and the alkalinity is preferably provided, at least in part, by means of sodium carbonate. Other preferred alkaline buffers include sodium silicate.

Heretofore, liquid detergent compositions have usually contained significant concentrations of hydrotropes and/or organic hydroxyl solvents which are miscible with water, e.g. methanol, ethanol, isopropanol, glycol, glycerol, polyethylene glycol and polypropylene glycol. However, these are expensive and are not functional components. They can, in special cases, promote pourability and enable a surfactant to more easily form a spherulitic phase. They are therefore not totally excluded from all compositions according to the invention, but it is preferred that the presence of these compounds is limited to the minimum required to ensure a spherulitic composition with the desired pourability. If they are not required, it is preferred that the connections are not present. Solvents must in some cases be present as components of perfumes or other of the usual minor constituents.

The dry weight of the composition affects the stability and pourability. Optimum dry weight can vary considerably from one type of composition to another, and can be chosen to provide the desired viscosity. In general, it has not been possible to guarantee stable compositions below 35% dry weight by weight, although some types of compositions can be obtained in a stable form below 30% dry weight, and in some cases as low as 25% dry weight. The possibility of producing stable compositions at a dry weight down to 20% is not ruled out.

For a given formulation, a range of dry weights can be identified, within this range the composition is both stable and pourable. Below this range, sedimentation will generally take place, and above the range the composition is too viscous. The acceptable range can be routinely determined for any given composition by preparing the suspension with the minimum amount of water required to maintain a stirrable composition, then diluting a number of samples to incrementally greater dilutions, and observing the samples for signs of sedimentation during a suitable period. For some compositions the acceptable range of dry weights may extend from 30% or 35%, to 60 or even 70% by weight, for others it is much narrower, e.g. 40-45% by weight.

If no stable, pourable range can be determined by the methods described above, the composition should be modified according to the description, e.g. by adding more sodium carbonate, sodium silicate solution or other electrolyte if the composition shows stage I or II properties, or by reducing the electrolyte content or adding hydrotrope, if the composition shows stage IV or V properties. Alternatively, if difficulties arise in finding a stable spherulitic system, by exclusively changing the electrolyte content, one can change the active ingredients by adding a foam-stabilizing surfactant, such as e.g. alkyl ether sulfate, alkanolamide or amine oxide, if the composition forms stage IV or V, or by adding alkylbenzenesulfonate or alkyl sulfate if stage I or II predominates.

The compositions according to the invention can, in many cases, be easily prepared by normal mixing of the components. It is characteristic of the preferred compositions that they do not destabilize or thicken when subjected to high shear forces.

The order and conditions for mixing the components are in some cases important when producing a stable, structured composition according to the invention.

Compositions according to the invention can typically be obtained for any suitable active ingredient, by first preparing a clear, aqueous L^ solution of the active ingredients, at a suitable concentration (e.g. 15 to 30 wt% active ingredient) by heating, if necessary, and dissolving the electrolyte in the I^ solution or adding concentrated electrolyte solution (preferably functional electrolyte), until the mixture becomes opaque. A sample of the mixture is then centrifuged at 20,000 G for 5 minutes. If a clear, aqueous phase is observed, more electrolyte is added to the mixture until high G centrifugation no longer gives evidence of a separate, mostly clear, aqueous phase. The weight ratio between active ingredient and dissolved electrolyte is then noted.

A composition containing all the desired ingredients and having a weight ratio of active ingredient to electrolyte as determined can then be prepared at the desired percentage dry weight (typically 40 to 50%). Formation of a clear, aqueous base phase at high G centrifugation indicates the presence of lamellar phase, and the amount of electrolyte is then reduced until no clear phase is observed at high G centrifugation. Samples of the latter composition with different dry weights can be prepared to determine the optimum mobility/stability properties.

If difficulties arise in determining a suitable active ingredient/electrolyte ratio in the first step of the above procedure, the procedure can be repeated using a more soluble electrolyte, e.g. a non-functional electrolyte, such as sodium chloride or sodium nitrate. Alternatively, the active system can be modified by the addition of surfactants, which promote stable dispersions, e.g. ether sulfates, amine oxides or alkanolamides, if stage IV or V properties are observed, or a non-ethoxylated anionic surfactant if stage I or II properties are more easily obtained.

Typically, the mixture is carried out at room temperature where this provides adequate dispersion, certain components, e.g. non-ionic surfactants such as e.g. coconut mono-ethanolamide requires gentle heating, e.g. to 40° C to achieve adequate dispersion. This heating can generally be achieved by the heat of solution of sodium tripolyphosphate. To ensure sufficient heating, it is preferred to add the anhydrous form of tripolyphosphate which contains a sufficiently high proportion of the temperature raising modification, this is usually called "phase I". The above method is only one of several methods which can be used with advantage for all, or most, of the compositions according to the invention. Some compositions are more sensitive to the order and temperature of mixing than others.

By considering the different types of compositions according to the invention in greater detail, a distinction is made in particular between high-foaming sulfate or sulfonate-type compositions and low-foaming compositions.

High-foaming compositions can typically be based on mixtures of one or more non-ethoxylated anionic surfactants, preferably a sulfated or sulfonated surfactant, with one or more co-surfactants that form a stable foam, such as e.g. an ethoxylated anionic surfactant, an amine oxide or fatty alkanolamide. The first component of the active ingredients, i.e. the non-ethoxylated anionic surfactant, can e.g. be a C10-18~alkylsulfurate and/or C10-14-alkylbenzenesulfonate. The second component or co-surfactant may be a sodium C10-20 straight or branched alkyl C1-4 mole ether sulfate or an alkylphenol betasulfate, amine betasulfate, alkanolamide ethersulfate or fatty acid ethersulfate. Alternatively, or in addition, the second component may include an amine oxide or fatty alkylolamide. The total weight ratio between non-ethoxylated, anionic and. co-surfactant, may typically be from 5:1 to 1:3, preferably 4:1 to 1:2, e.g. 3:1 to 1:1. Small amounts (eg up to 1% by weight of the composition) of soap may be present to assist in cleaning the textiles. Ethoxylates may be present in smaller proportions, typically up to >20% by weight of the total amount of active ingredients, preferably less than 15%, usually less than 10%.

The sodium alkyl sulfate or alkyl benzene sulfonate can be completely or partially replaced in the above compositions by other sulfonated, non-ethoxylated surfactants including fatty alkylxylene or toluene sulfonates, or paraffin sulfonates, olefin sulfonates, sulfocarboxylates, and their esters and amides, including sulfosuccinates and sulfosuccinates. Alkyl ether sulfate can be completely or partially replaced by other ether sulfates such as e.g. alkyl phenyl ether sulfates, fatty acyl monoethyl amide ether sulfates or mixtures thereof.

A particular embodiment of the composition according to the present invention is a stable, pourable spherulitic composition comprising: water; from 12 to 40% dry weight of active ingredients, based on the dry weight of the composition, and from 20 to 80% dry weight of builders, based on the dry weight of the composition, which are at least partially present as suspended solids, and partially as at least part of the dissolved electrolyte; and wherein the active ingredients consist of (A) from 20 to 80% by weight of a non-alkylated anionic, sulfated or sulfonated surfactant, and (B) from 20 to 70% by weight of the total surfactant of at least one foam stabilizing co-surfactant such as e.g. an alkoxylated anionic surfactant, an alkanolamide or an amine oxide. Optionally, the aforementioned composition may additionally contain soap in an amount of up to 6% of the dry weight of the composition. Preferably, the non-alkylated sulphated or sulphonated anionic surfactant consists essentially of alkyl sulphate or alkylbenzenesulphonate, preferably sodium alkylbenzenesulphonate, e.g. C10-14-Alkylbenzenesulfonate.

Alternatively, the anionic surfactant may include a mixture of alkylbenzene sulphonate and/or alkyl sulphate with alkyl ether sulphate and/or alkyl phenol ether sulphate in a weight ratio of e.g. from 1:3 to 5:1, typically 1:2 to 4:1, preferably 1:1 to 3:1, e.g. 2:1.

Low-foaming compositions can be prepared by using suitable foam inhibitors. The choice of foam inhibitor must be made with care, because certain commercially available foam inhibitors may lose their effect upon storage in the compositions according to the invention, while others are only effective at concentrations high enough to affect the viscosity or stability of the composition. Mixtures of organopolysiloxane and colloidal silica have been found to be particularly effective.

Another special edition of the composition according to the invention is than a stable, pourable, liquid, water-based detergent composition which includes: from 12 to 40%, based on the dry weight of the composition of active ingredients which is from 30 to 90%, based on the dry weight of active ingredients, of non-alkylated, sulfated and/or sulfonated anionic surfactant, and otherwise alkyl ether sulfate and/or an alkanolamide or amine oxide; an aqueous phase containing sufficient electrolyte in solution to form a space-filling, spherulitic floc containing the active ingredients moved into the aqueous phase; suspended particles of building; an effective amount of at least one foam inhibitor and optionally the usual minor ingredients.

A further composition within the present invention is a pourable, stable detergent composition which has a useful weight of from 30% to 50% which mainly consists of from 12 to 40% dry weight of active ingredients, based on the dry weight of the composition, at least 30% builder, based on the dry weight of the composition, a ratio of builders to active ingredients greater than 1.1 to 1, wherein the active ingredients consist essentially of alkylbenzenesulfonate having 8 to 18 aliphatic carbon atoms, and an alkylethanolamide selected from Ciø_i8~alkylmonoethanolamides °9 diethanolamides, at a weight ratio between alkylbenzene sulphonate and ethanolamide of from 1.5:1 to 4:1, where the builder is selected from sodium tripolyphosphate, sodium carbonate, zeolite, sodium nitrilotriacetate, sodium silicate and mixtures thereof, so that the amount of dissolved builder is sufficient to provide a yield strength greater than 1.5 dyne cm-<2>.

Another advantageous composition within the present invention is a pourable, stable, liquid detergent composition, which essentially consists of: A. A mixture of (i) a sodium alkylbenzene sulfonate having 10 to 18, preferably 10 to 14 aliphatic carbon atoms and (ii) a sodium alkyl ether sulfate having an alkyl group with an average of from 8 to 18, preferably 10 to 14 carbon atoms, and from 1 to 20, preferably 2 to 10, e.g. 3 to 5 ethyleneoxy and/or propyleneoxy groups; at a ratio of (i):(ii), between 10:1 and 1:10, especially 10:1.5 to 10:5, e.g. 10:2 to 10:4; B. A builder selected from sodium tripolyphosphate, zeolite, sodium nitrilotriacetate and mixtures thereof, at a weight ratio of B:A of from 1.1:1 to 4:1, preferably 1.2:1 to 3.5:1, e.g. . 2:1 to 3:1; C. An electrolyte selected from sodium carbonate, sodium silicate, sodium nitrate, sodium chloride and mixtures thereof, in concentrations of from 2 to 20% by weight, preferably 3 to 18% by weight, especially 7 to 15% by weight of the composition;

where the composition has a useful weight of 30 to 50% by weight, preferably 35 to 50% by weight, e.g. 38 to 45% by weight; and the composition preferably contains minor but effective amounts of anti-redeposition agents, preferably sodium carboxymethyl cellulose, perfume, dye and optical brighteners.

The sodium cation in the above compositions may optionally, but less preferably, be completely or partially replaced by potassium, lithium or ammonium. Preferably, the sodium tripolyphosphate constitutes from 40 to 95% of the total weight of building, e.g. 45% to 80%. Preferably, the composition contains at least one foam inhibitor if this is required for automatic washing.

The above compositions may possibly contain smaller amounts of alkanolamide, such as e.g. a coconut monoethanolamide or diethanolamide, or of ethoxylated nonionic surfactant.

The compositions according to the invention may contain the usual minor components. The most important of these are anti-deposition agents, dispersants, optical brighteners and bleaching agents.

The most commonly used anti-redeposition agent used in the manufacture of detergents is sodium carboxymethyl cellulose (SCMC), which can be present in the compositions in effective amounts that can be reconciled with the desired viscosity and stability. In general, SCMC is effective at concentrations of approx. 1% and it is preferred not to exceed this normally effective concentration because SCMC in larger amounts can increase the viscosity of a liquid composition very significantly, it can also affect stability.

Alternative anti-redeposition and/or soil release agents include potassium, ammonium and other soluble CMC salts, phosphonates, methylcellulose, polyvinylpyrrolidone, carboxymethyl starch and similar polyelectrolytes, all of which can be used in place of SCMC.

Optical brighteners (OBAs) are optional but preferred components of the compositions. In contrast to some previously known compositions, the present compositions do not depend on OBA to achieve stability, and one can therefore freely choose any appropriate and cost-effective OBA, or omit such agents. It has been found that any of the fluorescent dyes which have hitherto been recommended for use as OBA in liquid detergents can be used, as can many dyes which are normally suitable for use in washing powders. OBA may be present in conventional amounts. The concentration of OBA between 0.05 and 0.5% is sufficient, e.g. 0.075 to 0.3%, typically 0.1 to 0.2%. Lower concentrations can be used but are unlikely to be effective, while higher concentrations, although not excluded, are likely to be cost-effective and in some cases may present compatibility issues.

Typical examples of OBA that can be used in the present invention include: ethoxylated 1,2-(benzimidazolyl)-ethylene"; 2-styrylnaphth[1,2-d]oxazole; "1,2-bis(5'-methyl-2- benzoxazolyl)ethylene; disodium 4,4'-bis(6-methylethanolamine-3-anilino-1,3,5-triazin-2"-yl)-2,2'-stilbenesulfonate; N-(2-hydroxyethyl-4,4'- bis(benzimidazolyl)stilbene;tetrasodium-4,4'-bis[4"-bis(2"-hydroxyethyl)-amino-6"-(3"-sulfophenyl)-amino-1" ,3" ,5"-triazine -2"-yl-amino]-2,2'-stilbenesulfonate; disodium 4-(6"-sulfonaphto[1',2'-d]triazol-2-yl)-2-stilbene-sulfonate; disodium- 4,4'-bis[4"-(2"'-hydroxyethoxy)-6"-amino-1",3",5"-triazin-2"-yl-amino]-2,2'-stilbenesulfonate; 4 -methyl-7-dimethylaminocoumarin; and alkylated 4,4'-bis(benz-imidazolyl)stilbene.

Bleaching agents can optionally be incorporated into liquid detergent compositions, where they are compatible and chemically stable. Encapsulated bleaches may form part of the suspended solids. The effect of peroxy-bleaching agents in the compositions according to the invention can be increased by the presence of bleaching activators such as e.g. tetraacetylethylenediamine, in effective amounts. Photoactive bleaching agents, such as e.g. zinc or aluminum sulphonated phthalocyanine, may also be present.

Perfumes and dyes are conventionally present in laundry detergents in amounts of up to 1 to 2%, and can correspondingly be present in the compositions according to the invention. One must

in some cases use care when choosing a suitable perfume,

because the solvents present can modify the behavior of the active ingredients.

Proteolytic and amylolytic enzymes may optionally be present in conventional amounts, optionally together with enzyme stabilizers and carriers. Encapsulated enzymes may be suspended in the composition.

Other minor ingredients include antifoam, alkali, bactericidal agents, such as formaldehyde, opacifying agents, such as e.g. vinyl latex emulsion, inert abrasives, such as silicon oxide and anticorrosives such as e.g. benzotriazole.

The compositions according to the invention are generally suitable for washing clothes. Low-foaming compositions are particularly useful in automatic washing machines. The compositions can also be used for washing dishes, or cleaning hard surfaces, the low-foaming products are particularly useful for use in dishwashers.

Compositions according to the invention can generally be used for washing clothes in boiling water, or for washing at medium or low temperatures, e.g. respectively 50 to 80'C, especially 55 to 68<0>C, or 20-50°C, especially 30-40'C. The compositions can be added to the wash water in a concentration of between 0.05 and 3% dry weight, based on the amount of the wash water, preferably 0.1 to 2%, usually 0.3 to 1%, e.g. 0.4 to 0.8%.

The invention is illustrated by the examples given in the following tables.

The compositions in the examples were stable and pourable. They were stable when stored at 40°C and were non-shear sensitive. They were temperature stable and, except for Example 83, they were shear stable.

The drawings show variations in conductivity, yield point and viscosity as a function of variations in electrolyte concentration and in active ingredients.

Fig. 1 is a curve showing the conductivity of an aqueous 20.6% solution of active ingredients consisting of 2 parts by weight of sodium dodecylbenzenesulfonate and 1 part of sodium C 1 -alkyl 3 mol ethoxysulfate, with varying amounts of sodium silicate with Na 2 O:Si( >2 mole ratio 1:1.6 The numbers on the horizontal axis refer to the amount of silicate in the composition expressed as % by weight of solids.

Between 0 and 7% added silicate solution gives a substantially clear, optically isotropic composition typical of stage I, described earlier. Between points "A" and "B" stage II compositions are obtained, which are cloudy, unstable and include non-space-filling flocks of spherulites. Between "B" and "C" step III compositions according to the present invention are obtained. These are cloudy, stable compositions containing mainly space-filling flocks of spherulites, which exhibit a yield point and which exhibit a single liquid phase on high G centrifugation. After "C", stage IV compositions containing non-space-filling flocks of spherical G phase, which are unstable, are obtained. It appears that stable stage III compositions are achieved in the conductivity valley at the first conductivity minimum. Fig. 2 shows the effect of adding sodium nitrate to the same aqueous active system. Beyond point "C" in stage IV, a second conductivity maximum is passed, followed by a second conductivity minimum, corresponding to the formation of a lamellar composition according to stage V near "D". Fig. 3 shows variations in viscosity, conductivity and yield point when sodium carbonate is added to the same active system.

The left axis indicates viscosity at 136 sec.-<1> in pascal seconds, the numbers in parentheses indicate conductivity in milliSiemens cm""<1>; the right-hand scale indicates yield strength in dyne cm"<2>; the horizontal axis indicates the total percentage of sodium carbonate present, expressed as dry weight of sodium carbonate, based on the total weight of the composition.

In the case of sodium carbonate, no minimum is observed in the conductivity curve (dotted line). This is because the solubility limit for sodium carbonate has been reached, so that further additions of carbonate go into suspension and do not increase the concentration of dissolved electrolyte. No stage IV can therefore be observed. The rapid increase in yield point (top right) coincides with the entry of stage III at point "B". This is typical for the compositions according to the invention. Fig. 4 shows the effect of variations in the relative proportions of sodium dodecylbenzenesulfonate and coconut monoethanolamide in a composition containing sodium dodecylbenzenesulfonate, sodium tripolyphosphate, sodium carbonate and water in a ratio of 0.2:0.5:0.1:1.0. The horizontal axis indicates the weight ratio of coconut monoethanolamide to sodium dodecylbenzene sulfonate. The vertical axis indicates conductivity in mS cm-<1 > (circles), and also viscosity in pascal seconds x 10 (triangles). Fig. 5 shows a corresponding relationship where coconut mono-ethanolamide is replaced by sodium C12-18-alkyl 3 mol ethoxysulphate. The horizontal axis indicates the weight ratio between ether sulfate and alkylbenzene sulfonate. Fig. 4 and 5 show how it is possible to prepare compositions according to the invention by modifying the active ingredients. Fig. 6 shows the variations in conductivity in mS cm-<1> when sodium nitrate is added in different proportions to a detergent composition containing suspended builders and having the composition:

Because of the dissolved tripolyphosphate already present, step I is not observed at this curve. The conductivity falls from a maximum at "A" until stage III occurs at "B". Fig. 7 shows the yield strength for the same system, in dyn cm-<2 >and fig. 8 shows the viscosity at 136 cm-<1> (lower curve), 21 cm-<1> (upper curve) and the drop in viscosity (middle curve) in pascal seconds x 10. Fig. 9 shows the changes in conductivity with varying amounts of sodium silicate in a 20.6% by weight aqueous solution of sodium dodecylbenzenesulfonate mixed with coconut monoethanolamide in a weight ratio of 10:4.

Again no stage I is observed, this time because the active ingredients are not fully soluble in water at room temperature. The composition is therefore unclear and unstable when electrolyte is not present.

Figs 10 and 11 show transmission micrographs of the Pt/C replica, after freeze-fracture, at magnifications of x 45,000 and x 110,000 respectively.

The micrographs, which were produced using the transmission electron microscope at Lancaster University, represent both samples having the composition:

The micrographs show spherulites between 0.2 and 1 pm in diameter, which show signs of being multiple vesicles with a concentric structure, they have a repeated spacing (including the thickness of a surface shell and a neighboring water layer) of 80 Å.

Claims (1)

Stable, pourable, liquid detergent composition comprising water, surfactant, dissolved electrolyte salt that acts to de-solubilize the surfactant, and suspended particles of a solid builder, whereby the total weight ratio of the builder when any dissolved builder is included, to the surfactant is greater than 1.5:1, and in which composition the surfactant's weight ratio to water is such that when said salt is continuously dissolved in said surfactant, in the aqueous micelle solution where "said" weight ratio prevails, the curve for the solution's electrical conductivity is a function of the salt concentration through a wave valley area, containing a minimum for electrical conductivity, whereby the solution is stable and unclear, characterized in that of said salt, when a possibly dissolved build is included, a total amount corresponding to the said wave valley is dissolved in said composition -area, what quantity is chosen between the minimum and maximum quantities at which the composition is stable for at least 3 months both at room temperature and at a temperature of 5'C, e.g. at 0°C, and preferably also at 40<*>C.