EP0934384B1

EP0934384B1 - Enzymatic compositions

Info

Publication number: EP0934384B1
Application number: EP97945848A
Authority: EP
Inventors: Johannes Cornelis van de Unilever Res lab PAS; Willem R. Van Dijk; Marja Unilever Res Vlaardingen Lab OUWENDIJK; David Alan Unilever Research Lab. REED; Lisa Jane Unilever Research Lab. THOMAS
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1996-10-15
Filing date: 1997-10-14
Publication date: 2003-02-12
Anticipated expiration: 2017-10-14
Also published as: AU734832B2; DE69719050D1; ES2191859T3; ZA979227B; CA2268788A1; BR9711927A; AU5119898A; EP0934384A1; WO1998016607A3; WO1998016607A2; GB9621436D0; AR009116A1; DE69719050T2

Description

FIELD OF THE INVENTION

The present invention relates to aqueous detergent compositions which contain enzymes.

BACKGROUND OF THE INVENTION

It is well known in the art that enzymes can lose their activity with time when included in an aqueous liquid detergent composition, and various proposals have already been made to retard that loss of activity by including in such compositions an enzyme-stabilising system. Various enzyme stabilisers have been suggested in the art for inclusion in liquid detergent compositions, e.g. polyols (e.g. glycerol), borax (preferably in combination with glycerol), calcium ions, alcohols, low molecular weight carboxylates (formate, acetate, propionate, etc.) and polymers (e.g. poly-vinyl-pyrollidone).

Borax, usually in the presence of glycerol, is a very commonly used enzyme stabiliser and is very effective. However, concerns about the negative environmental impact of boron mean that there is a need to formulate substantially without use of boron-containing compounds yet to achieve comparable enzyme stability.

It has now been found that this objective can be achieved in the case of structured aqueous liquid detergent compositions by a combination of two or more formulation steps. By structured aqueous liquid detergent composition is meant those compositions which contain sufficient detergent-active material and, optionally, sufficiently dissolved electrolyte to result in a structure of lamellar droplets dispersed in a continuous aqueous phase.

Lamellar droplets are a particular class of surfactant structures which, inter alia, are already known from a variety of references, e.g. H.A. Barnes, "Detergents", Ch. 2, in K. Walters (Ed), "Rheometry: Industrial Applications", J. Wiley & Sons, Letchworth 1980.

Such lamellar dispersions are used to endow properties such as consumer-preferred flow behaviour and/or turbid appearance. Many are also capable of suspending particulate solids such as detergency builders or abrasive particles. Examples of such structured liquids without suspended solids are given in US patent 4 244 840, whilst examples where solid particles are suspended are disclosed in specifications EP-A-160 342; EP-A-38 101; EP-A-104 452 and also in the aforementioned US 4 244 840. Others are disclosed in European Patent Specification EP-A-151 884, where the lamellar droplet are called 'spherulites'.

The presence of lamellar droplets in a liquid detergent product may be detected by means known to those skilled in the art, for example optical techniques, various rheometrical measurements, X-ray or neutron diffraction, and electron microscopy.

The droplets consist of an onion-like configuration of concentric bi-layers of surfactant molecules, between which is trapped water or electrolyte solution (aqueous phase). Systems in which such droplets are close-packed provide a very desirable combination of physical stability and solid-suspending properties with useful flow properties.

UK patent specification GB-A-2 245 280 discloses examples of structured aqueous liquid detergents in which the ratio of water-soluble salt to water is more than 0.25:1 and containing an enzyme of undefined solubility. The compositions contain 0.1% by weight of calcium acetate.

SUMMARY OF THE INVENTION

The selection of formulation steps to achieve the desired enzyme stability without substantial use of boron-containing enzyme stabilisers is defined by the present invention which provides a liquid detergent composition comprising a dispersion of lamellar droplets in an aqueous continuous phase, the composition further comprising an enzyme and being characterised by at least two of the following three features (i)-(iii):-

(i) the weight ratio of total water-soluble salt to water in the total composition is at least 0.4:1;

(ii) the solubility of the enzyme in a 25% sodium citrate.0aq solution in deionised water is at most 50% by weight of the total added enzyme; and

(iii) the composition further comprises at least one non-Boron-containing enzyme stabiliser at a level of at least 0.01% by weight;

wherein the enzyme has a residual activity of at least 10% after storage of the composition at 37°C for 4 weeks from the time of making; and wherein the composition contains no more than 0.01% by weight of Boron; provided that if only features (i) and (iii) are present and the non-Boron containing enzyme stabiliser comprises a water-soluble calcium salt, then the total amount of water-soluble calcium salt is at least 0.3% by weight of the total composition; and if all of features (i), (ii) and (iii) are present, then the non-Boron containing enzyme stabiliser comprises at least one material other than a lignin compound.

The solubility of the enzyme is defined as the percentage of total enzyme activity present in the supernatant after centrifuging for 15 minutes at 16,000g a solution of deionised water comprising of sodium citrate (25% by weight) and enzyme. A typical enzyme dosage for this solubility test is 0.4% by weight of a (commercial) liquid enzyme preparation containing typically 4% enzyme procein. In case of proteases the activities before and after centrifugation are determined at 40°C and pH 9.0 using acetylated caseine as a substrate and reacting quantitatively the formed amine-groups with 2,4,6-trinitrobenzene sulphonic acid. The change in absorbance at 405nm is used a measure for activity.

DETAILED DESCRIPTION OF THE INVENTION

The pH of compositions according to the present invention is preferably greater than 6, more preferably greater than 7 and most preferably greater than 7.5. On the other hand, the pH is preferably less than 11, more preferably less than 10 and most preferably less than 9.5.

Especially preferred are those compositions which combine all of features (i) - (iii).

If feature (iii) is utilised, the amount of the non-Boron-containing enzyme stabiliser in the composition is at least 0.01% by weight but more preferably, this minimum is 0.03%, especially 0.05%. In ascending order, still more preferred minima for this amount (by weight) are 0.1%, 0.2% and 0.5%.

The non-Boron-containing enzyme stabiliser may for example be selected from lignin compounds, alkali metal mono- or dicarboxylates, sources of calcium ions preferably in the presence of sequestrants and enzyme stabilising polymers.

Suitable lignin compounds are those described in our published International Patent Application No. WO 97/00932. The latter document exemplifies compositions exemplifying all of features (i), (ii) and (iii) of the present invention wherein a lignin compound is used as a non-Boron containing enzyme stabiliser. These compositions are thus disclaimed from the scope of the present invention.

Generally speaking, the lignin compounds are mixtures of components and are usually referred to as a polymer which contains, amongst others, phenylpropane units. Lignin compounds can be prepared from the chemical pulping of hard- and softwoods. Lignin compounds have been found to be very effective compounds according to the present invention. There are various lignin compounds which are preferred enzyme stabilisers according to the invention, including lingnosulphonates, Kraft lignins and oxylignins. All these compounds are considered lignin compounds. These compounds may be prepared from Lignin by various ways, including:

1) treatment with hot (acid) solution of calcium bisulphite which generates Lignosulphonates. The Lignin undergoes a sulphonation and a hydrolysation process under the influence of sulphite.

2) treatment with hot alkaline (pH 13-14) solution of sodium sulphate generates Kraft Lignins, which may subsequently be modified in various ways, e.g. sulphonated, methylated, carboxylated and/or fractionated.

3) reducing the sulphur content of lignosulphonate raw material and optionally applying condensation, cleavage and/or rearrangement, to reduce the number of sulphonic and methoxyl groups and to increase the number of functional phenolic, hydroxyl and carboxylic groups generates oxylignins.

Further variations to Lignin or any of its derivatives may be made by varying the kind of cation (Na⁺, K⁺, Ca²⁺, Mg²⁺, NH₄ ⁺, the degree of sulphonation and/or the average molecular size).

Examples of lignin derivatives that have been found useful are Borresperse NA, Borresperse CA, Kelig FS, Maracarb N-1, Marasperse N-22, Marasperse N-3, Norlig BD, Norlig 415, Ufoxane 2, Ufoxane 3A, Maracell 3A, Vanisperse CB, Ultrazine NA, Ultrazine CA (all ex Borregaard) and lignosulphonates ex Aldrich and ex Sigma as well as ex a number of pharmaceutical companies.

We have found that inclusion of lignin compounds significantly retards the enzyme deactivation, and most surprisingly, lignin compounds are effective as stabiliser at low concentration. Consequently, lignin compounds are included in effective amounts in the composition, in particular in the range of 0.0001 to 10%, preferably 0.001 to 5%, more preferably at least 0.01 and more preferably at most 3% by weight of the composition.

Although the weight ratio between lignin compound and enzyme (as defined as the weight of the active enzyme protein material, which does not include any additives that for example may be present in the enzyme preparations as supplied by the enzyme manufacturers) may be varied widely, as long as the enzyme is effectively stabilised, a weight ratio between 1000:1 and 1:10 has been found to be preferred, more preferably lower than 500:1, most preferably lower than 100:1, in particular lower than 50:1, whereas it is more preferred to have a weight ratio of higher than 1:5, most preferably higher than 1:3, in particular 1:2, more in particular 1:1.

Preferably, the molar ratio between the total lignin compound and total enzyme is from 0.1 to 10,000, more preferably at least 1 and at most 5,000, most preferably at least 2.

Suitable enzyme stabilising alkali metal mono- or dicarboxylate include alkali metal formates, e.g. sodium formate and acetate and propionate, as well as sodium succinate, sodium maleate, sodium glutamate and sodium aspartate.

Suitable enzyme-stabilising sources of calcium ions include any water-soluble calcium salt, such as calcium chloride, as well as calcium formate and calcium acetate.
Preferably, sequestants are present when calcium is present, for example, phosphorous containing Dequest (Trade mark of Monsanto) and non-phosphorous containing sequestrants, for example the amino(poly)carboxylates, e.g. salts of glutamic acid N,N-diacetic acid, beta-alanine diacetic acid, ethylenediamine triaceticacid, methyl glycine diacetic acid, diethylenetriamine penta-acetic acid, ethylenediamine-N,N-disuccinic acid and ethylenediamine di(sulfosuccinate).

Suitable enzyme-stabilising polymers include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl acetate, polyvinyl immidazole, as well as copolymers thereof.

More than one non-boron containing enzyme stabiliser may be utilised in the same formulation.

The composition must contain no more than 0.01% by weight of Boron. Preferably the composition is substantially Boron-free. It is more preferred that the maximum Boron content by weight of the total composition is 0.005%, still more preferably 0.003 and especially 0.001%.

If feature (ii) of the present invention is utilised, then one suitable class of enzymes which meet the solubility criterion defined by feature (ii) is that described in our co-pending Patent Application No. WO 96/34935 claiming priority from European Patent Application No 95201161.7 filed 5 May 1995 (and unpublished at the priority date of the present application). These enzymes are subtilase variants wherein one or more amino acid residues situated in or in the vicinity of a hydrophobic domain of the parent subtilase have been substituted for an amino acid residue more hydrophobic than the original residue, said hydrophobic domain comprising the residues P129, P131, 1165, Y167, Y171 of BLS309 (in BASBPN numbering), and the residues in the vicinity thereof comprises residues corresponding to the residues E136, G159, S164, R170, A194 and G195 of BLS309 (in BASBPN numbering), with the exception of the R170M, R1701 and R170V variants of BABP92. The substitution(s) may be combined with substitutions, insertions or deletions in any other position.

Preferably the original amino acid residue has been substituted for a residue selected from the group comprising Val (V), Ile (I), Leu (L), Met (M), Phe (F), and Trp (W), preferably Val, Ile or Leu.

The parent subtilase is preferably chosen from the subgroup I-S1 or I-S2.

Another example of a suitable enzyme variant meeting the solubility criterion of feature (ii) is Relase as marketed by Novo Nordisk and described in Patent application EP-A-405 901.

Apart from enzyme variants, also "wild-type" enzymes can meet the solubility criterion of feature (ii).

Enzymes can be available in various forms, such as:

enzyme liquids, where the enzyme is present in an aqueous solvent. Examples of this class are the L-type liquids as marketed by Novo Nordisk
enzyme slurries, where the enzyme is present in a substantially non-aqueous solvent, such as a liquid nonionic surfactant. Examples of this class are the SL-type and SL LDP-type slurries as marketed by Novo Nordisk
encapsulates of enzymes.

Liquids, slurries and encapsulates may contain a mixture of enzymes selected from protease, lip(ol)ase, amylase, cellulase, etc. All these enzyme forms can be used in the present invention.

The residual activity of the enzyme is at least 10% as determined as hereinbefore described. Preferably though, this minimum is at least 25%, more preferably 40%, still more preferably 50% and most preferably 75%.

Moreover, the enzyme solubility when determined as hereinbefore described in respect of feature (ii) is at most 50% by weight of the total added enzyme. Preferably though, this maximum is 25%, more preferably 10%, still more preferably 5% and especially 2%.

If feature (ii) is not utilised, then the enzyme may be chosen from any of those known in the art of formulating enzyme-containing detergent compositions and even if feature (ii) is utilised the composition may additionally contain one or more additional enzymes selected from such known enzymes. In general, such enzymes may be selected from proteases, amylases, lipases, cellulases and mixtures of one or more of these enzymes. Proteases are preferred enzymes for use in the present invention, as we have seen the best results with protease stabilisation.

Depending on the type of composition and whether or not an enzyme meeting the criterion of feature (ii) is actually incorporated, the enzyme(s) preferably provide (as appropriate) a proteolytic activity between 0.1 and 50 GU/mg, a lipolytic activity between 0.005-100 LU/mg and an amylolytic activity between 10³ and 10⁷ MU/kg, wherein GU, LU and MU units are well known in the art and have e.g. been defined in lines 8-14 of column 3 and lines 8-12 and 21-24 of column 4 of US 5,112,518.

Depending on the composition type, the level of active enzyme protein will be higher (up to 10%, preferably up to 5% by weight for concentrated enzyme preparations, e.g. as supplied by enzyme manufacturers) or tower (up to 3%, preferably up to 1.0%, although levels up to 0.5% or up to 0.1% or even as low as up to 0.05% are also suitable for more dilute systems, e.g. commercial liquid detergent compositions in which the concentrated enzyme preparations are used during production). The active enzyme protein level may be as low as 0.0001%, preferably at least 0.01% by weight of the composition. Again in more concentrated enzyme preparations, the lower level will be higher, e.g. at least 0.5% by weight.

If feature (i) is utilised, the weight ratio of the total water-soluble salt (electrolyte) to water in the total composition is at least 0.40:1. Preferred minima for this weight ratio are, in ascending order 0.45:1, 0.50:1, 0.55:1, 0.60:1 and 0.65:1. Preferably also, the maximum value of this weight ratio is 1.0.

As used herein the term "water-soluble salt includes both the salt(s) from the formulation that totally dissolves and the dissolved part of the salt(s) that does not totally dissolve, expressed as anhydrous salts.

The compositions of the present invention are aqueous dispersions of lamellar droplets. Although it is possible to form lamellar dispersions of surfactant in water alone, in many cases it is preferred for the aqueous continuous phase to contain dissolved electrolyte. As used herein, the term electrolyte means any ionic water-soluble material. However, in lamellar dispersions, not all the electrolyte is necessarily dissolved but may be suspended as particles of solid because the total electrolyte concentration of the liquid is higher than the solubility limit of the electrolyte. Mixtures of electrolytes also may be used, with one or more of the electrolytes being in the dissolved aqueous phase and one or more being substantially only in the suspended solid phase. Two or more electrolytes may also be distributed approximately proportionally, between these two phases. In part, this may depend on processing, e.g. the order of addition of components. On the other hand, the term 'salts' includes all organic and inorganic materials which may be included, other than surfactants and water, whether or not they are ionic, and this term encompasses the sub-set of the electrolytes (water-soluble materials).

The only restriction on the total amount of detergent-active material and electrolyte (if any) is that in the compositions of the invention, together they must result in formation of an aqueous lamellar dispersion. Thus, within the ambit of the present invention, a very wide variation in surfactant types and levels is possible. The selection of surfactant types and their proportions, in order to obtain a stable liquid with the required structure will be fully within the capability of those skilled in the art. However, it can be mentioned that an important sub-class of useful compositions is those where the detergent-active material comprises blends of different surfactant types. Typical blends useful for fabric washing compositions include those where the primary surfactant(s) comprise nonionic and/or a non-alkoxylated anionic and/or an alkoxylated anionic surfactant.

In addition to the above described conventional structured liquids, the stability of compositions of the present invention may be enhanced, or the rheology of such compositions may be controlled by incorporation of a deflocculating polymer such as any described in EP-A-346 995 or in any of WO91/06622; WO91/06623; GB-A-2,237,813; WO91/09109; US-A-5,494,602; EP-A-623,670; US-A-5,489,397; and EP-A-691,399.

In many (but not all) cases, the total detergent-active material may be present at from 2% to 60% by weight of the total composition, for example from 5% to 40% and typically from 10% to 30% by weight. However, one preferred class of compositions comprises at least 20%, most preferably at least 25%, and especially at least 30% of detergent-active material based on the weight of the total composition. In the case of blends of surfactants, the precise proportions of each component which will result in such stability and viscosity will depend on the type(s) and amount(s) of the electrolytes, as in the case with conventional structured liquids.

In the widest definition the detergent-active material in general, may comprise one or more surfactants, and may be selected from anionic, cationic, nonionic, zwitterionic and amphoteric species, and (provided mutually compatible) mixtures thereof. For example, they may be chosen from any of the classes, sub-classes and specific materials described in 'Surface Active Agents' Vol. 1. By Schwartz & Perry, Interscience 1949 and 'Surface Active Agents' Vol. II by Schwarz, Perry & Berch (Interscience 1958), in the current edition of "McCutcheon's Emulsifiers & Detergents" published by the McCutcheon division of Manufacturing Confectioners Company or in 'Tensid-Taschenbuch', H. Stache, 2nd Edn., Carl Hanser Verlag, München & Wien, 1981.

Suitable nonionic surfactants include, in particular, the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide, either alone or with propylene oxide. Specific nonionic detergent compounds are alkyl (C₆-C₁₈) primary or secondary linear or branched alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic detergent compounds include long chain tertiary amine oxides, long-chain tertiary phospine oxides and dialkyl sulphoxides.

Suitable anionic surfactants are usually water-soluble alkali metal salts of organic sulphates and sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates, especially those obtained by sulphating higher (C₈-C₁₈) alcohols produced, for example, from tallow or coconut oil, sodium and potassium alkyl (C₉-C₂₀) benzene sulphonates, particularly sodium linear secondary alkyl (C₁₀-C₁₅) benzene sulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulphates and sulphonates; sodium and potassium salts of sulphuric acid esters of higher (C₈-C₁₈) fatty alcohol-alkylene oxide, particularly ethylene oxide, reaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralised with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyl taurine; alkane monosulphonates such as those derived by reacting alpha-olefins (C_8-20) with sodium bisulphite and those derived from reacting paraffins with SO₂ and Cl₂ and then hydrolysing with a base to produce a random sulphonate; and olefin sulphonates, which term is used to describe the material made by reacting olefins, particularly C₁₀-C₂₀ alpha-olefins, with SO₃ and then neutralising and hydrolysing the reaction product. The preferred anionic detergent compounds are sodium (C₁₁-C₁₅) alkyl benzene sulphonates and sodium (C₁₆-C₁₈) alkyl sulphates.

Also possible is that part or all of the detergent active material is a stabilising surfactant, which has an average alkyl chain length greater than 6 C-atoms, and which has a salting out resistance, greater than, or equal to 6.4. These stabilising surfactants are disclosed in our European patent application EP-A-328,177. Examples of these materials are alkyl polyalkyloxated carboxylates, alkyl polyalkoxylated phosphates, alkyl polyalkoxylated sulphosuccinates; dialkyl diphenyloxide disulphonates; alkyl polysacccharides and mixtures thereof.

It is also possible, and sometimes preferred, to include an alkali metal soap of a long chain mono- or dicarboxylic acid for example one having from 12 to 18 carbon atoms. Typical acids of this kind are oleic acid, ricinoleic acid, and fatty acids derived from castor oil, rapeseed oil, groundnut oil, coconut oil, palm kernel oil or mixtures thereof. The sodium or potassium soaps of these acids can be used.

Preferably the amount of water in the composition is from 5 to 95%, more preferred from 25 to 75%, most preferred from 30 to 50%. Especially preferred less than 45% by weight.

The compositions optionally also contain electrolyte in an amount sufficient to bring about structuring of the detergent-active material. Preferably though, the compositions contain from 1% to 60%, especially from 10 to 45% of a salting-out electrolyte. Salting-out electrolyte has the meaning ascribed to in specification EP-A-79 646. Optionally, some salting-in electrolyte (as defined in the latter specification) may also be included, provided if of a kind and in an amount compatible with the other components and the composition is still in accordance with the definition of the invention claimed herein. Some or all of the electrolyte (whether salting-in or salting-out), or any substantially water-insoluble salt which may be present, may have detergency builder properties. In any event, it is preferred that compositions according to the present invention include detergency builder material, some or all of which may be electrolyte. The builder material is any capable of reducing the level of free calcium ions in the wash liquor and will preferably provide the composition with other beneficial properties such as the generation of an alkaline pH, the suspension of soil removed from the fabric and the dispersion of the fabric softening clay material.

Examples of phosphorous-containing inorganic detergency builders, when present, include the water-soluble salts, especially alkali metal pyrophosphates, orthophosphates, polyphosphates and phosphonates. Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, phosphates and hexametaphosphates. Phosphonate sequestrant builders may also be used.

Examples of non-phosphorus-containing inorganic detergency builders, when present, include water-soluble alkali metal carbonates, bicarbonates, silicates and crystalline and amorphous aluminosilicates. Specific examples include sodium carbonate (with or without calcite seeds), potassium carbonate, sodium and potassium bicarbonates, silicates and zeolites.

In the context of inorganic builders, we prefer to include electrolytes which promote the solubility of other electrolytes, for example use of potassium salts to promote the solubility of sodium salts. Thereby, the amount of dissolved electrolyte can be increased considerably (crystal dissolution) as described in UK patent specification GB 1 302 543.

Examples of organic detergency builders, when present, include the alkaline metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates, polyacetyl carboxylates, carboxymethyloxysuccinates, carboxymethyloxymalonates, ethylene diamine-N,N, disuccinic acid salts, polyepoxysuccinates, oxydiacetates, triethylene tetramine hexacetic acid salts, N-alkyl imino diacetates or dipropionates, alpha sulpho- fatty acid salts, dipicolinic acid salts, oxidised polysaccharides, polyhydroxysulphonates and mixtures thereof.

Specific examples include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilitriacetic acid, oxydisuccinic acid, melitic acid, benzene polycarboxylic acids and citric acid, tartrate mono succinate and tartrate di succinate.

In the context of organic builders, it is also desirable to incorporate polymers which are only partly dissolved in the aqueous continuous phase. This allows a viscosity reduction (owing to the polymer which is dissolved) whilst incorporating a sufficiently high amount to achieve a secondary benefit, especially building, because the part which is not dissolved does not bring about the instability that would occur if substantially all were dissolved.

Examples of partly dissolved polymers include many of the polymer and co-polymers salts already known as detergency builders. For example, may be used (including building and non-building polymers) polyethylene glycols, polyacrylates, polymaleates, polysugars, polysugarsulphonates and co-polymers of any of these. Preferably, the partly dissolved polymer comprises a co-polymer which includes an alkali metal salt of a polyacrylic, polymethacrylic or maleic acid or anhydride. Preferably, compositions with these co-polymers have a pH of above 8.0. In general, the amount of viscosity-reducing polymer can vary widely according to the formulation of the rest of the composition. However, typical amounts are from 0.5 to 4.5% by weight.

It is further possible to include in the compositions of the present invention, alternatively, or in addition to the partly dissolved polymer, yet another polymer which is substantially totally soluble in the aqueous phase and has an electrolyte resistance of more than 5 grams sodium nitrilotriacetate in 100 ml of a 5% by weight aqueous solution of the polymer, said second polymer also having a vapour pressure in 20% aqueous solution, equal to or less than the vapour pressure of a reference 2% by weight or greater aqueous solution of polyethylene glycol having an average molecular weight of 6,000; said second polymer having a molecular weight of at least 1,000.

The incorporation of the soluble polymer permits formulation with improved stability at the same viscosity (relative to the composition without the soluble polymer) or lower viscosity with the same stability. The soluble polymer can also reduce viscosity drift, even when it also brings about a viscosity reduction. Here, improved stability and lower viscosity mean over and above any such effects brought about by the deflocculating polymer.

It is especially preferred to incorporate the soluble polymer with a partly dissolved polymer which has a large insoluble component. That is because although the building capacity of the partly dissolved polymer will be good (since relatively high quantities can be stably incorporated), the viscosity reduction will not be optimum (since little will be dissolved). Thus, the soluble polymer can usefully function to reduce the viscosity further, to an ideal level.

The soluble polymer can, for example, be incorporated at from 0.05 to 20% by weight, although usually, from 0.1 to 10% by weight of the total composition is sufficient, and especially from 0.2 to 3.5 - 4.5% by weight. It has been found that the presence of deflocculating polymer increase the tolerance for higher levels of soluble polymer without stability problems. A large number of different polymers may be used as such a soluble polymer, provided the electrolyte resistance and vapour pressure requirements are met. The former is measured as the amount of sodium nitrilotriacetate (NaNTA) solution necessary to reach the cloud point of 100 ml of a 5% solution of the polymer in water at 25°C, with the system adjusted to neutral pH, i.e. about 7. This is preferably effected using sodium hydroxide. Most preferably, the electrolyte resistance is 10 g NaNTA, especially 15 g. The latter indicates a vapour pressure low enough to have sufficient water binding capability, as generally explained in the Applicants' specification GB-A-2 053 249. Preferably, the measurement is effected with a reference solution at 10% by weight aqueous concentration, especially 18%.

Typical classes of polymers which may be used as the soluble polymer, provided they meet the above requirements, include polyethylene glycols, Dextran, Dextran sulphonates, polyacrylates and polyacrylate/maleic acid co-polymers.

The soluble polymer must have an average molecular weight of at least 1,000 but a minimum average molecular weight of 2,000 is preferred.

The use of partly soluble and the use of soluble polymers as referred to above in detergent compositions is described in our European patent applications EP-A- 301 882 and EP-A-301 883.

Although it is possible to incorporate minor amounts of hydrotropes such as lower alcohols (e.g. ethanol) or alkanolamines (e.g. triethanolamine), in order to ensure integrity of the lamellar dispersion we prefer that the compositions of the present invention are substantially free from hydrotropes. By hydrotrope is meant any water soluble agent which tends to enhance the solubility of surfactants in aqueous solution.

Apart from the ingredients already mentioned, a number of optional ingredients may also be present, for example lather boosters such as alkanolamides, particularly the monoethanolamides derived from palm kernel fatty acids and coconut fatty acids, fabric softeners such as clays, amines and amine oxides, lather depressants, oxygen-releasing bleaching agents such a sodium perborate and sodium percarbonate, peracid bleach precursors, chlorine-releasing bleaching agents such as trichloroisocyanuric acid, inorganic salts such as sodium sulphate, and, usually present in minor amounts, oily-soil release polymers e.g. those sold under Trademarks Permalose, Aquaperle and Gerol, fluorescent agents, perfumes, germicides and colorants.

The invention will no be illustrated by way of the following Examples. In all Examples, unless stated to the contrary, all percentages are by weight.

EXAMPLES Example 1

Component	%w/w
LAS -acid	16.5
Nonionic (Dobanol 25-7)	9
Oleic acid (Priolene 6907)	4.5
Zeolite	15
KOH, neutralisation of acids and pH to 8.5
Citric Acid	8.2
Deflocculating polymer	1
Protease	0.38
Lipolase	0.2
Oily soil release polymer Aquaperle	0.5
Minors	0.4
Water	to 100%

Enzyme	Residual activity 4 weeks 37°C	Features which are fulfilled
Relase 16 EXI	72%	(i), (ii) and (iii)
Note: Enzyme contains PVP

Example 2

Component	%w/w
K-LAS	25.2
LES	6.0
STPP	15.0
K-citrate	15.4
deflocculating polymer	1
Protease	var
Enzyme stabiliser of feature (iii)	x
Tinopal CBS-X	0.18
Perfume	0.5
Water	to 100%
pH, adjusted with KOH to 7.5 - 8

Enzyme (x)	Enzyme stabiliser (iii)	Residual activity 4 weeks 37°C	Features which are fulfilled
0.7% Alcalase 2.34L	None	30%	(i)
Ditto	0.5% CaCl₂ + 0.5% Dequest 2066	45%	(i) and (iii)
Ditto	PVP 0.05%	55%	(i) and (iii)
Ditto	0.5% PVP	62%	(i) and (iii)
*0.3% Savinase 16L EXI	None	35%	(i)
Ditto	0.5% CaCl₂ + 0.5% Dequest 2066	50%	(i) and (iii)
Ditto	0.05% PVP	55%	(i) and (iii)
Ditto	0.5% PVP	61%	(i) and (iii)
0.2% Relase 8.9L	None	35%	(i) and (ii)
Ditto	0.5% CaCl₂ + 0.5% Dequest 2066	55%	(i), (ii) and (iii)
Ditto	0.05% PVP	67%	(i), (ii) and (iii)
Ditto	0.5% PVP	81%	(i), (ii) and (iii)

Example 3

Component	%w/w
K-LAS	25.2
LES	6.0
STPP	22.0
K-citrate	3.1
deflocculating polymer	1
Protease	0.4%
Enzyme stabiliser of feature (iii)	x
Tinopal CBS-X	0.18
TiO₂	0.5
Perfume	0.5
Water	to 100%
pH, adjusted with KOH to 7.5-8

Enzyme	Enzyme stabiliser (iii)	Residual activity 4 weeks 37°C	Features which are fulfilled
Relase 16L EXI	none	44%	(i), (ii) and (iii)
ditto	0.25% extra PVP	65%	(i), (ii) and (iii)
Note: enzyme contains already PVP.

Example 4

Component	%w/w
K-LAS	23.6
Nonionic (Dobanol 25-7)	7.5
STPP	21.0
KTPP	9.0
deflocculating polymer	2
Protease	0.4%
Enzyme stabiliser of feature (iii)	x
Tinopal CBS-X	0.18
TiO₂	0.5
Perfume	0.5
Water	to 100%
pH, adjusted with KOH to 7.5-8

Enzyme	Enzyme stabiliser (iii)	Residual activity 4 weeks 37ºC	Features which are fulfilled
Relase 16L EXI	none	52%	(i), (ii) and (iii)
ditto	0.5% extra PVP	70%	(i), (ii) and (iii)
Note: enzyme contains already PVP

Example 5

Component	%w/w
LAS-acid	7.7
Nonionic (Dobanol 25-7)	2.3
STPP/KTPP	var
Na₂SO₄/K₂SO₄	var
Enzyme stabiliser of feature (iii)	var
deflocculating polymer	1
Relase 16L EXI	0.4
Tinopal CBS-X	0.1
Perfume	0.17
Proxel	0.02
Silicone oil, anti foam	0/0.25
Water	to 100%
PH, adjusted with KOH to 7.5-8

Electrolyte(s)	Enzyme stabiliser (iii)	Residual activity 4 weeks 37ºC	Features which are fulfilled
21% STPP	None	0%	(ii)
30% KTP	0.5% PVP	About 40%	(i), (ii) and (iii)
21% STPP 10% K₂SO₄	0.5% PVP	About 50%	(i), (ii) and (iii)

Example 6

Component	%w/w
LAS-acid	11.25
Nonionic (Dobanol 25-7)	3.75
STPP	var
Na₂SO₄	var
deflocculating polymer	3
Relase 16L EXI	0.4
Tinopal CBS-X	0.1
Perfume	0.17
Proxel	0.02
Silicon oil, anti foam	0/0.25
Water	to 100%
pH, adjusted with KOH to 7.5-8

Electrolyte(s )	Enzyme stabiliser (iii)	Residual activity 4 weeks 37ºC	Features which are fulfilled
5% STPP	none	89%	(i) and (ii)
20% Na₂SO₄ 7.5% STPP	none	74%	(i) and (ii)
15% Na₂SO₄
Note: enzyme contains already PVP

Example 7

Component	%w/w
LAS-acid	12%
LES	3%
STPP	10%
KOH	2.44%
Protease	0.4%
Enzyme stabiliser of feature (i)	15%
Tinopal CBS-X	0.09%
Deflocculating Polymer	0.25%
Water	to 100%

Enzyme	Enzyme stabiliser (i)	Residual Activity 4 weeks at 37°C	Features which are fulfilled
Relase 16L EXI	15% Na-sulphate 0aq	61%	(i), (ii) and (iii)
Savinase 16L EXI	15% Na-sulphate 0aq	38%	(i)
Savinase SL LDP	15% Na-sulphate 0aq	45%	(i), (ii) and (iii)

Example 8

Component	%w/w
K-LAS	23.6
Nonionic (Dobanol 25-7)	7.5
K-citrate	3.1
STPP	22
Protease	0.4
Enzyme stabliser of feature (iii)	0.3
Tinopal CBS-X	0.18
Soil Release Polymer	0.5
Deflocculating polymer	1
TiO₂	0.5
Perfume	0.5
Antifoam	0.6
Water	to 100%

Enzyme	Enzyme stabiliser (iii)	Residual Activity 4 weeks at 37°C	Features which are fulfilled
Relase 16L EXI	0.3% PVP	76%	(i), (ii) and (iii)

Raw Material Specification
Component	Specification
LAS-acid	Linear Alkyl Benzene Sulphonic-acid, Marion AS3, ex Huls
K-LAS	LAS-acid neutralised with KOH
Dobanol 25-7	C12-15 ethoxylated alcohol, 7EO, ex Shell
LES	Lauryl Ether Sulphate, Dobanol 25-S3, ex Shell
Oleic acid	Priolene 6907, ex Unichema
Zeolite	Wessalith P, ex Degussa
STPP	Sodium Tri PolyPhosphate, Thermphos NW, ex Hoechst
KTPP	Potassium Tri PolyPhosphate
Proxel	Preservative, ex ICI
CaCl₂	ex Chemproha
Dequest 2066	Metal chelating agent, ex Monsanto
Silicone oil	Antifoam, DB 100, ex Dow Corning
PVP	Poly Vinyl Pyrollidon, ex ISP Global Technologies
Tinopal CBS-X	Fluorescer, ex Ciba-Geigy
Aquaperle SRL	Oily Soil Release polymer, ex ICI
Lipolase	type 100L, ex Novo
Savinase SL LDP	Protease, ex Novo
Relase 16L EXI	Protease, ex Novo
Alcalase 2.34 L	Protease, ex Novo
Savinase 16L	Protease, ex Novo
Savinase 16L EXI	Protease, ex Novo
Relase 8.9L	Protease, ex Novo

In the light of this disclosure, modifications of the described examples, as well as other examples, all within the scope of the present invention as determined by the appended claims will now become apparent to persons skilled in the art.

Claims

A liquid detergent composition comprising a dispersion of lameilar droplets in an aqueous continuous phase, the composition further comprising an enzyme and being characterised by at least two of the following three features (i) - (iii):-

(i) the weight ratio of the total water-soluble salt to water in the total composition is at least 0.4:1;

(ii) the solubility of the enzyme in a 25% sodium citrate.0aq solution in deionised water is at most 50% by weight; and

(iii) the composition further comprises at least one non-Boron-containing enzyme stabiliser at a level of at least 0.01% by weight;

wherein the enzyme has a residual activity of at least 10% after storage of the composition at 37°C for 4 weeks from the time of making; and
wherein the composition contains no more than 0.01% by weight of Boron; provided that if only features (i) and (iii) are present and the non-Boron containing enzyme stabiliser comprises a water-soluble calcium salt, then the total amount of water-soluble calcium salt is at least 0.3% by weight of the total composition;
and if all of features (i), (ii) and (iii) are present, then the non-Boron containing enzyme stabiliser comprises at least one material other than a lignin compound.
A composition according to claim 1, characterised by all three of the said features (i)-(iii).
A composition according to any preceding claim, which composition is characterised by feature (i) which composition contains both sodium and potassium ions in a ratio for controlling the solubility of the water soluble salts.
A composition according to any preceding claim, which composition is characterised by feature (ii), wherein said enzyme is incorporated in the form of a liquid or slurry.
A composition according to any of claims 1-3, which composition is characterised by feature (ii), wherein said enzyme is incorporated in the form of an encapsulate.
A composition according to any preceding claim, which composition is characterised by feature (ii), wherein the residual activity of the enzyme is at least 25%.
A composition according to any preceding claim, which composition is characterised by feature (iii) and wherein the non-Boron containing enzyme stabiliser is selected from lignin compounds, alkali metal mono or dicarboxylates, sources of calcium ions and enzyme stabilising polymers.
A composition according to any preceding claim, which composition is characterised by feature (iii), wherein the amount of the non-Boron containing enzyme stabiliser is at least 0.03% by weight, preferably at least 0.05% by weight.
A composition according to any preceding claim, having a pH greater than 6, preferably greater than 7.
A composition according to any preceding claim, having a pH less than 11, preferably less than 10.
A composition according to any preceding claim, containing no more than 0.005%, preferably no more than 0.003% by weight of Boron.