GB2178055A - Stabilized built liquid detergent composition containing enzymes - Google Patents

Abstract

A stabilized enzyme-containing liquid detergent comprises (a) 5 to 20%, a non-cationic surface active detergent compound (b) 5 to 30%, of a builder salt; (c) 5 to 20%, of a swelling bentonite clay; (d) an effective amount of an enzyme of; (e) an enzyme-stabilizing system containing, based on the weight of the detergent composition, (i) 1% to 10% glycerine; (ii) 1 to 8% of boric acid, boric oxide or an alkali metal borate; and (iii) 0.5 to 8% of a of mono, di and/or polycarboxylic acid having 1 to 8 carbon atoms or a water-soluble salt thereof; and (f) water. e

Description

SPECIFICATION Stabilized built liquid detergent composition containing enzymes The present invention relates to stable, built, enzyme-containing liquid detergent compositions suitable for laundry or pre-soakformulations. More particularly, the present invention relates to aqueous enzymecontaining liquid detergent compositions which contain one or more detergent builders and which are characterised by being physically stable, homogeneous liquid compositions.

The formulation of stabilized enzyme-containing liquid detergent compositions has been the focus of much attention in the prior art. The desirability of incorporating enzymes into detergent compositions is primarily due to the effectiveness of proteolytic and amylolytic enzymes in decomposing proteinaceous and starchy materials found on soiled fabrics, thereby facilitating the removal of stains, such as, gravy stains, blood stains, chocolate stains and the like during laundering. However, enzymatic materials suitable for laundry compositions, particularly proteolytic enzymes, are relatively expensive. Indeed, they generally are among the most expensive ingredients in a typical commercial liquid detergent composition, even though they are present in relatively minor amounts. Moreover, enzymes are known to be unstable in aqueous compositions.

it is forthis reason that an excess of enzymes is generally required in liquid detergentformulations to com- pensate forthe expected loss of enzyme activity during prolonged periods of storage. Accordingly, the prior art is replete with suggestionsforstabilizing enzyme-containing liquid detergent compositions, and in part- ocular unbuilt liquid compositions by the use of various materials which are incorporated intothecomposi- tion to function as enzyme stabilizers.

In the case of liquid detergent compositions containing a builder, the problem of enzyme instability is particularly acute. Primarily this is because detergent builders have a destabilizing effect on enzymes, even in compositions containing enzyme stabilizers which are otherwise effective in unbuiltformulations. Moreover, the incorporation of a builder into a liquid detergent composition poses an additional problem, namely,the ability to form a stable single-phase composition; the solubility of sodium tripolyphosphate, forexample, being relatively limited in aqueous compositions, and especially in the presenceofanionicand nonionic detergents.

In U.K. PatentApplication G.B. 2,079,305, published 20th January, 1982, there is disclosed an aqueous built enzyme-containing liquid detergent composition which is stabilized by a mixture of a polyol and boric acid.

As noted in the examples ofthe U.K. application, relatively large amounts of glycerol are required to stabilize the enzymes in the composition. Yet, as demonstrated hereinafter in the present specification, the enzyme stabilizing effect provided by a mixture of glycerine and borax in a built aqueous liquid detergentcomposition is relatively modest.

In European Patent Application Publication No. 0126505, there is disclosed an aqueous enzyme-containing liquid detergent composition containing an enzyme stabilizing mixture consisting of certain dicarboxylic acids and borax. The dicarboxylic acids are recommended as a substitute for a polyol such as glycerol in known enzyme stabilizing mixtures consisting of glycerol and a boron compound. However, the dicarboxylic acid-borax mixtures of this publication in common with the aforementioned prior art mixture of glycerine and borax are incapable of providing anything otherthan a modest stabilizing effect in the present built liquid detergent compositions.

The present invention provides a stabilized fabric softening, enzyme-containing built liquid detergent composition comprising: (a) from about 5 to 20%, by weight, of one or more surface active detergent compounds selected fromthe group consisting ofanionic, nonionic and amphotericdetergentcompounds; (b)from about5to 30%, by weight, of one or more builder salts selected from the group consisting of alkali metal tripolyphosphates, alkali metal carbonates, alkali metal nitrilotriacetates, and poly-acetal carboxylates;; (c) from about 5 to 20%, by weight, of a swelling bentonite clay, (d) an effective amountofan enzyme or an enzyme mixture selected from the group consisting of alkaline protease enzymes and alpha-amylase enzymes; (e) an enzyme-stabilizing system containing, based on the weight of the detergent composition, (i) from about 1 to 10% glycerine; (ii)from about 1 to 8% of a boron compound selected from the group consisting of boric acid, boric oxide and alkali metal borates and; (iii) from about 0.5 to 8% of a carboxylic acid compound selected from the group consisting of mono, di and/or polycarboxylic acids having 1 to 8 carbon atoms and water-soluble salts thereof; and (f)the balance comprising water and optionally perfume and otheradjuvants.

In a preferred embodiment of the present invention, the liquid detergent composition comprises (a)from about 5 to 15% of an alkali metal alkylbenzene sulphonatewherein the alkyl group contains 12 to 1 5 carbon atoms; (b) from about2to 5% ofan alkali metal alkyl polyethoxy sulphate wherein the alkyl group contains 10to 18 carbon atoms and the polyethoxy is of to 11 ethylene oxide groups, the weight ratio of (a) to (b) being from about 2:1 to about 8: 1; (c) from about 5 to 20% of sodium tripolyphosphate; (d) from about 1 to 10% ofsodium carbonate,theweight ratio of (c) to (d) being from about 2:1 to about6:1; (e) from about 10 to 15% of a sodium bentonite; (f) an effective amount ofthe aforesaid enzyme or enzyme mixture; (g) an enzyme stabilizing system containing, based on the weight of the detergent composition, (i) from about3to 7% glycerine, (ii)from about 1 to 5% of an alkali metal borate and (iii) from about 0.5 to 4% ofthe said carboxylic acid compound; and (h) the balance comprising water and optionally perfume and other adjuvants.

In accordance with the process of the present invention, laundering of stained and/or soiled materials is affected by contacting such materials with an aqueous solution ofthe above-defined liquid detergent compositions.

The described liquid detergent is a commercially acceptable heavy duty laundry detergent, capable of satisfactorily cleaning laundry items containing both oily and particulate soils. Additionally, the described compositions may be employed for the pre-treatment of badly soiled areas, such as collars and cuffs, of items to be laundered.

The present invention is predicated upon the discovery of a three component enzyme stabilizing system as herein defined which provides an enzyme stabilizing effectto the liquid detergent compositions of the pre- sent invention far in excess ofthatwhich can be achieved with conventional enzyme stabilizers. The enzyme stabilizing effect thus achieved reflects a synergy among the three components.In accordance with the present invention,the enzyme stability provided by a mixture of glycerine and borax or a mixture of borax and a dicarboxylic acid as disclosed in the prior art can be synergistically improved by the use ofthethree compo nent stabilizing system herein defined in the present liquid compositions so as to raise the level of enzyme stability significantly above that provided by either the mixture of glycerine and borax or the mixture of borax and dicarboxylic acid when used independently of each other as enzyme stabilizers. For commercial purposes, a desirable enzyme stability generally corresponds to about a half-life of one week at a temperature of 110 F (43 C).

The enzyme stabilizing system of the present invention is a mixture of glycerine, a boron compound selected from among boric acid, boric oxide and an alkali metal borate and a carboxylic acid compound as herein defined. The weight of the stabilizing system in the present built liquid detergent compositions is generally from about3 to 25%, preferably about 6 to 15%, by weight. The weight ratio of glycerine to borax in the stabilizing mixtures is generally from about 1 to 3. The preferred amount ofglycerine in the composition is from about 1 to 5%, and the preferred amount of carboxylic compound is from about O.5to4% based onthe weight of the composition.

The carboxylic acid compounds which are useful in the enzyme stabilizing system of the present invention encompass saturated as well as unsaturated mono, di and polycarboxylic acids having 1 to 8 carbon atoms among which are included oxalic acid (HOOCCOOH), malonic acid, (HOOCCH2COOH), maleic acid (HOOCCH:CHCOOH)and succinic acid (HOOCCH2CH2COOH). The carboxylic acids may contain hydroxy or amino substituents as exemplified by malic acid (HOOCCHOHCH2COOH), tartaric acid (dihydroxysuccinic acid) aspartic acid (amino succinic acid) and citric acid. Preferred carboxylic acids ofthe present invention are aspartic acid, tartaric acid, malonic acid and malic acid. From a commercial standpoint, a particularly preferred carboxylic acid compound is citric acid and/or its salts because of their relatively low cost.

The alkaline proteolytic enzymes suitable for the compositions of the present invention include the various commercial liquid enzyme preparations which have been adapted for use in detergent compositions. Enzyme preparations in powdered form are also useful although, as a general rule, less convenient for incorporation into the built liquid detergent compositions. Thus, suitable liquid enzyme preparations include "Alcalase" and "Esperase" sold by Novo Industries, Copenhagen, Denmark, and "Maxatase" and "AZ-Protease" sold by Gist-Brocades, Delft,The Netherlands.

Among the suitable a-amylase liquid enzyme preparations arethose sold underthetradenames "Termamyl" and Mazamyl", respectively.

"Esperase" is particularly preferred for the present compositions because of its optimized activity at the higher pH values corresponding to the built detergent compositions.

The preferred detergents for use in the present liquid compositions are the synthetic anionic detergent compounds, and particularly a mixture of higher alkylbenzene sulphonate and alkyl polyethoxy sulphate.

While other water soluble higher alkyl-benzene sulphonates may also be present in the formulas of the pre sentinvention,such as potassium salts and in some instances the ammonium oralkanol-ammonium salts, where appropriate, it has been found that the sodium salt is highly preferred, which is also the case with respect to the alkyl polyethoxy sulphate detergent component. The alkylbenzene sulphonate is onewherein the higher alkyl group is of 12 to 15 carbon atoms, preferably 13 carbon atoms.The alkyl polyethoxy sulphate, which also may be referred to as a sulphated polyethoxylated higher linear alcohol orthe sulphated condensation product of a higherfatty alcohol and ethylene oxide or polyethoxylene glycol, is one wherein the alkyl group is of 10 to 18 carbon atoms, preferably 12 to 15 carbon atoms, e.g. about 13 carbon atoms, and which includes 3to 11 ethylene oxide groups, preferably 3 to 7, more preferably 3to 5 and most preferably 3 or about 3 ethylene oxide groups. The ratio of alkylbenzene sulphonateto polyethoxy sulphate in the detergent mix- ture is preferably from about 2:1 to 6:1 and most preferablyfrom about 2:1 to 4:1, by weight. At ratios above 5:1, the physical stability of the product may be adversely affected.

In suitable circumstances other anionic detergents, such as fatty alcohol sulphates, paraffin sulphonates, olefin sulphonates, monoglyceride sulphates, sarcosinates and similarly functioning detergents, preferably as the alkali metal, e.g. sodium salts, can be present, sometimes in partial replacement ofthe previously mentioned synthetic organic detergents but usually, if present, in addition to such detergents. Normally,the supplementing detergents will besulphated orsulphonated products (usually as the sodium salts) andwill contain long chain (8to 20 carbon atoms) linear orfatty alkyl groups.In addition to any supplementing anionic synthetic organic detergents, there also may be present nonionic and amphoteric materials, likethe Neodols (Registered Trade Mark), sold by Shell Chemical Company, which are condensation products of ethylene oxide and higherfatty alcohols, e.g. Neodol (Registered Trade Mark) 23-6.5, which is a condensation product of a higher fatty alcohol of about 12 to 13 carbon atoms with about 6.5 moles of ethylene oxide.

Illustrations ofthe various detergents and classes of detergents mentioned may be found in the test Surface ActiveAgents, Vol. II, by Scwartz, Perry and Berch (lnterscience Publishers, 1958), the descriptions ofwhich are incorporated herein by reference.

The builder salt combination ofthe present invention, which has been found to satisfatorily improvethe detergencyofthe mixture ofsyntheticanionicorganic detergents and produce the desired pH in the liquid detergent and in the wash water, is a mixture of sodium tripolyphosphate and sodium carbonate. The builder salts are employed in the compositions of the present invention in amounts generally of from about 5 to 25%, by weight.Forthe preferred builder salt combination, sodium tripolyphosphate is present in amounts of from about 5 to 20%, preferably 1 to 16%, and sodium carbonate is present from about 1 to 10%, byweight, preferably 3 to 7%, the weight ratio oftripolyphosphate to carbonate in the preferred builder mixtures being from about 2:1 to 4:1. As used herein, the term alkali metal "carbonates" or "carbonate" is meantto include the carbonates, bicarbonates and sesquicarbonates of such alkali metals.

For best processing, easier mixing and good enduse properties it is preferred thatthe sodium tri- polyphosphate be low in content of Phase I type tripolyphosphate. Thus, normally the content of Phase I type tripolyphosphate will be less than 30% of the tripolyphosphate employed.Although in some instances in- completely neutralized tripolyphosphate may be used, normallythe phosphate employed may be considered as being pentasodium tripolyphosphate, Na5P3O10. Of course, in some instances, as when potassium salts of other materials are present, ion interchange in an aqueous medium may result in other salts than the sodium tripolyphosphate being present but forthe purpose of this specification it will be considered that sodium tripolyphosphate, as the pentasodium salt, the material which is normally charged to the mixerto makethe present liquid detergent, is the tripolyphosphate employed.

Other preferred builder salts which may be used in place of sodium tripolyphosphate and sodium carbonate or in addition thereto include a polyacetal carboxylate as herein described and sodium nit rilotriacetate (NTA). Of course, various mixtures of the mentioned water soluble builder saits can be utilized.

Yet, the tripolyphosphate-carbonate mixture described has been found to be most preferred, although the other builders and mixtures thereof are also operative. Other builders which may be employed assupplements, in addition to the proportions ofthe above-mentioned builders, include other phosphates, such as tetrasodium pyrophosphate ortetrapotassium pyrophosphate, sodium bicarbonate, sodium citrate, sodium gluconate, sodium silicate, and sodium sesquicarbonate. Among the water insoluble builders that may be used are the zeolites, such as Zeolite A, usually in the form of its crystalline hydrate, although amorphous zeolites may also be useful.

Polyacetal carboxylates are generally described in U.S. Patents 4,144,226 and 4,315,092. U.S. Patent 4,146,495 described detergent compositions containing polyacetal carboxylates as builders.

The polyacetal carboxylates which are useful herein as builders may be considered to be those described in U.S. Patent 4,144,226 and may be made by the method mentioned therein. Atypical such product will be of the formula

wherein M represents an alkali metal, or ammonium, oran alkyl group of 1 to4carbon atoms, oratetraalkylammonium group oran alkanolamine group, both of 1 to4carbon atoms in the alkylsthereof, n averages at least 4, and R1 and R2 represent any chemically stable group which stabilizes the polymer against rapid depolymerization in alkaline solution.Preferablythe polyacetal carboxylate will be one wherein M is alkali metal, e.g. sodium, n is from 50 to 200, R1 is

ora mixture thereof, R2is

and n averages from 20 to 100, more preferably 30 to 80. The calculated weight average molecular weights of the polymers will normally be within the range of 2,000 to 20,000, preferably 3,500 to 10,000 and more preferably 5,000 to 9,000, e.g. about 8,000.

A particularly preferred sodium polyacetal carboxylate is supplied by Monsanto Company and is known as Builder U. It has a calculated weight average molecularweight of about 8,000 and an active polymer content of about 80%.

Although the preferred polyacetal carboxylates have been described above, it is to be understood thatthey may be wholly or partially replaced by other such polyacetal carboxylates or related organic buildersalts described in the previously cited patents on such compounds, processes for the manufacture thereof and compositions in which they are employed. Also, the chain terminating groups described inthevarious patents, especially U.S. 4,144,226, may be utilized, providing thatthey have the desired stabilizing properties, which allowthe mentioned builders to be depolymerized in acidic media, facilitating biodegradation thereof in waste streams, but maintain their stability in alkaline media, such as washing solutions.

The bentonite employed in the present invention is a colloidal clay (aluminium silicate) containing montmorillonite. Swelling bentonites are generally characterised as sodium bentonites, i.e. bentonitewherein the predominant cation is sodium. Among the sodium bentonite clays, those from Wyoming (generally referred to as Western or Wyoming bentonite) are especially preferred.

The swelling capacity of bentonite is generally associated with its fabric softening properties. In waterthe swelling capacity ofsodium bentonite is in the range of 3to 20 millilitres/gram, preferably 7to 1 Sml/gram, and its viscosity, at 6% concentration in water, is usually in the range of 3 to 30 centipoises, preferably 8 to 30 centipoises.

Preferred swelling bentonites are sold underthe trademark HI-JEL by Georgia Kaolin Co. These materials are the same as bentonites which were formerly sold underthetrademarks MINERAL COLLOID and THIXO JEL. They are selectively mined and beneficiated bentonites, and those considered to be most useful are available as HI-JELL Nos. 1,2,3 etc., corresponding to THIXO-JELS No's 1,2,3 and 4. Such materials have a maximum free moisture content (before addition to the liquid medium) of 4% to 8% and specific gravities of about 2.6. The bentonite is preferably one which will pass through a 200 mesh U.S.Sieve Series sieve, and most preferably at least 90% of the particles will pass through a No 325 sieve, so that the equivalent diameter of the bentonite may be considered to be less than 74 microns, and more preferably less than about 44 microns.

Typical chemical analyses of some bentonites that are useful for making the liquid detergents ofthe present invention show thatthey contain from 64.8 to 73.0% of Sill, 14to 18% of Al 203, 1.6 to 2.7% of MgO, 1 .3to 3.1% of CaO, 2.3 to 3.4% of Fe203, 0.8 to 2.8% of Na2O and 0.4 to 7.0% of K20.

Although the western bentonites are preferred it is also possible to utilize other bentonites, such as those which may be made by treating Italian orsimilar bentonites containing relativelysmall proportions of ex changeable monovalent metals (sodium and potassium) with alkaiine materials, such as sodium carbonate, to increase the cation exchange capacities of such products. It is considered thatthe Na2O content ofthe bentonite should be at least about 0.5%, preferably at least 1% and more preferably at least 2% so that the clay will be satisfactorily swelling, with good softening and dispersing properties in aqueous suspension. Preferred swelling bentonites of the types described above are sold underthe trade names Laviosa and Winkelmann, e.g. Laviosa AGB and Winkelmann G-13.

Other bentonites which are particularly useful for the present liquid detergent compositions because of their white or very light colour include American Colliod Company's Polarite KB 325, a California bentonite, and Georgia Kaolin's GK 129, a Mexican bentonite.

The only other required component ofthe liquid detergents ofthe present invention is water. Normallythe hardness content of such waterwill be less than about 300 ppm, as CaCO3, and preferably it will be lessthan 150 ppm. Often it may be desirable to utilize deionized water although city water with less than 50 or 100 p.p.m. hardness content will frequently be equally satisfactory.

Various adjuvants may be present in the liquid detergents of the present invention, such as fluorescent brighteners, perfumes and colourants. The fluorescent brighteners include the well known stilbene deri vatives, including the cotton and nylon brighteners, such asthose sold underthetrademarkTinopal (5BM Conc.). The perfumes that are employed usually include essential oils, esters, aldehydes and/or alcohols, all of which are known in the perfumery art. The colourants may include dyes and water dispersible pigments of various types, including ultramarine blue. lnorganicfillersalts, such as sodium sulphate and sodium chloride may be present, as may be antiredeposition agents, such as sodium carboxymethylcellulose; dispersing agents, such as sodium polyacrylate; bleaches; bactericides; fungicides; anti-foam agents; such assil- icones; antisoiling agents, such as copolyesters; preservatives such as formalin; foam stabilizers, such as lauric myristic diethanolamide; and auxiliary solvents, such as ethanol.Normally the individual proportions of such adjuvants will be less than 3%, often less than 1 % and sometimes even less than 0.5%, exceptfor any fillers and solvents, and additional detergents and buildersforwhich the proportions may sometimes beas high as 10%. The total proportion of adjuvants, including non-designated synthetic detergents and builders, will normally be no more than 20%ofthe product and desirably will be less than 10% thereof, more desirably less than 5% thereof. Of course, the adjuvants employed will be selected so as not to interfere with the washing action of the liquid detergent and to avoid instability ofthe product on standing.Also, adjuvants which cause the production of objectionable deposits on the laundryareto be avoided.

The liquid compositions of the present invention are efficient and easy to use. Compared to heavy duty laundry detergent powders, much smaller volumes ofthe liquids ofthe present invention are employed to obtain comparable cleaning of soiled laundry. For example, using atypical preferred formulation ofthe present invention, only about 132 grams or 1/2 cup of liquid is needed for a full tub of wash in atop-loading washing machine in which the water volume is 15 to 18 gallons (57 to 68 litres); and even less is needed for front-loading machines. Thus, the concentration of the liquid detergent composition in the wash water is of the order of about 0.2%. Usually, the amount of the liquid composition in the wash solution will rangefrom about 0.05 to 0.3%, preferably from 0.15 to 0.25%.The proportions of the various constituents ofthe liquid composition may vary accordingly. Equivalent results can be obtained by using greateramountsofa more dilute formulation but the greater quantity needed will require additional packaging and will generally be less convenientforconsumer use and may also result in product separation.

The viscosity ofthe liquid detergent composition of the present invention is normally in the range of about 1000 to 10,000 centipoises, preferably 2000-5000 centipoises, but products of other suitableviscosities may also be useful. At the viscosities mentioned, the liquid detergent is pourable, stable, non-separating and uniform. The pH ofthe liquid detergent suspension usually in the range of 7to 11.5, preferably8to 10.5, appears two helpto maintain productstabilityand pourability.

The invention may be put into practice in various ways and a number of specific embodiments will be described to illustrate the invention with reference to the accompanying examples. Unless otherwise indicated all parts are by weight and temperatures are in "C.

Example 1 A liquid detergent composition is made up with the ingredients and proportions shown in Table 1 below.

Table 1 Component Percent Pentasodium tripolyphosphate 11.0 Bentonite (Georgia-Kaolin 129) 12.0 Sodium carbonate 2.0 Sodium sesquicarbonate 2.0 Sodium lineartridecylbenzenesulphonate 8.0 AEOS(') 3.0 Carboxymethyl cellulose (CMC) 0.2 Optical brightener 0.3 Perfume 0.4 Enzyme (Esperase8.OL)(2) 1.0 Glycerine 3.0 Borax 2.5 Citric Acid 2.0 Water and adjuvants Balance Notes on Table 1: (1) Sodium alkyl polyethoxy sulphate wherein the alkyl group is of 12 to 15 carbon atoms and the polymethoxy is of 3 ethoxygroups.

(2) "Esperase" sold by Novo Industries having an activity of 8.0 KNPU/gram (Kilo Novo Protease units/gm.

The composition set out in Table 1 was prepared by the following procedure: 30.0 parts of deionized water at40"F (4"C) are added to a suitable mixing apparatus such as a vertical cylindricai tank equipped with a stirrer. With the stirrer adjusted for medium agitation, a mixture consisting of 2.0 parts anhydrous soda ash, 2.0 parts sodium sesquicarbonate, and 0.2 parts sodium carboxymethyl cellulose is incorporated into the water. The stirrer speed is then increased to maximum agitation and a mixture comprised of 11.0 parts pentasodium tripolyphosphate and 12.0 parts bentonite is slowly added to the mixing apparatus over a period of 10-15 minutes to form an off-white suspension.The agitation speed is then decreased to a slow/ medium setting while 8.64 parts of a high Al (about 55%) LTBS (lineartridecylbenzenesulphonate) slurry is added. Thereafterthe optical brightener/coloursolution is added consisting of 0.3 parts Tinopal LMS-X (CIBA-GEIGY), 0.99 parts colourant, and 4.02 parts deionized water. Once a uniform blueish-green coloured solution is obtained, 0.4 parts of perfume are added to the mixture underagitation.This is followed bythe slow addition of 3.0 parts glycerine and 2.5 parts borax as a two component slurry. Stirring is continued until the mixture is uniform in appearance and then 2.0 parts of sodium citrate and 9.0 parts water are slowly added.Agitation of the mixture is then reduced while 10.95 parts of a mixed Al detergent base consisting of an LTBS slurry (about 30% Al) and AEOS (about 27.5% Al) is added to the mixture. This is followed by the slow addition of 1.0 part proteolytic enzyme with continuous agitation until all materials are completely dispersed or dissolved.

Examples2A to2G Enzyme-containing built liquid detergent compositions, Examples 2Ato 2G, were formulated as setforth below in Table 2. The percentages shown indicate weight percent. It will be appreciated that the compositions are identical in respect of the first ten components listed in Table 2.

Examples 2Ato 2F are comparison examples.

Table 2 Component 2A 2B 2C 20 2E 2F 2G Pentasodium tripolyphosphate 11.0 11.0 11.0 11.0 11.0 11.0 11.0 Bentonite 12.0 12.0 12.0 12.0 12.0 12.0 12.0 (Georgia-Kaolin 129) Sodium Carbonate 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Sodium sesquicarbonate 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Sodium lineartridecylbenzenesulphonate 8.0 8.0 8.0 8.0 8.0 8.0 ? 8.0 AEOS(2' 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Optical brightener 0.3 0.3 0.3 0.3 0.3 0.3 0.3 (Tinopal LMS-X) Perfume 0.4 0.4 0.4 0.4 0.4 0.4 0.4 CMC 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Enzyme(2) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Glycerine - 3.0 - 3.0 - - 3.0 Borax - - 2.5 2.5 - 2.5 2.5 Carboxylic acid - - - - 2.0 2.0 2.0 compound Water and Balance adjuvants Notes on Table 2:: (1) Sodium alkyl polyethoxy sulphate wherein the alkyl group is of 12 to 15 carbon atoms and the polyethoxy is 3 of ethoxy groups.

(2) "Esperase" sold by Novo Industries having an activity of 8.0 KNPU/gm (Kilo Novo Protease units/gm).

The enzyme activities ofthe compositions of Examples 2Ato 2G were tested after 7 days storage at 11 0"F (43"C). The measured enzyme activity for each composition after thins period of storage is indicated inTables 3Ato 3Cand Table4as a percent of the initial value. The various carboxylic acids and salts used inthe formulas ofthe compositions of Examples 2Ato 2D are shown in Table 3A as well as the enzyme activities corresponding to each composition; for Example 2E in Table 3B (these all being comparison examples) and for Example 3G in Table 3C (this being in accordance with the invention).

Table 3A Enzyme stability PercentActive EnzymeAfter 7 Daysat 1 lO"F Example Composition (43"cm 2A (control) ND* 2B (with glycerine) ND 2C (with borax) ND 2D (with glycerine and borax) 45 Composition E (with carboxylic acid compound) wherein the carboxylic acid compoundis:: PercentActive EnzymeAfter 7 Daysat llO"F Example Composition (43" C) 2E(1) Succinicacid ND* 2E(2) Malonicacid ND 2E (3) Malicacid ND 2E(4) Tartaricacid ND 2E(5) Asparticacid ND 2E(6) Citric acid ND 2E (7) Sodiumtartrate ND 2E (8) Sodium citrate ND Note on Tables 3A and3B *ND = Not detectable (below 10% residual activity).

Table 3C Composition G (with glycerinelboraxicarboxylic acid compound) wherein the carboxylic acid compound is: PercentActive EnzymeAfter 7 Days at 110 F Example Composition (43" C) 2G (1) Succinicacid 70 2G (2) Malonicacid 70 2G (3) Malicacid 78 2G (4) Tartaricacid 73 2G (5) Asparticacid 90 2G (6) Citric acid 74 2G (7) Sodium tartrate 66 2G (8) Sodium citrate 52 As is evident from Table 3A, the control composition of Example 2A, as well as the comparison compositions of Examples 2B and 2C which contained glycerine and borax, respectively, as individual stabilizers, manifested almost no enzyme activity after the 7 days storage period of 11 0"F (43"C).Since enzyme activities below 10% could not be precisely measured they are designated "ND".The comparison composition of Example 2D containing glycerine and borax in the absence of a carboxylic acid compound provided an improvement in enzyme stability relative to the compositions of Examples 2Ato 2C but about 50% of the enzyme was deactivated. The various comparison compositions of Examples 2E(l)to 2E(8) containing a variety of carboxylic acid compounds but no borax or glycerine, as indicated, manifested absolutely no improvement in enzyme stability relative to the compositions of Examples 2Ato 2C.However, the compositions of Examples 2G(1 ) to 2G(8) formulated in accordance with the invention (using the same carboxylic acids) demonstrate the unexpected and synergistic improvement in enzyme stability which is achieved with the use of glycerine and borax in combination with a carboxylic acid compound in liquid detergent compositions as required by the present invention. It is noted that almost every one of the compositions corresponding to Examples 2G(1 ) to 2G(8) demonstrated a significant improvement in enzyme activity relative to the composition of Example 2D (containing only glycerine and borax).

A comparison of the enzyme activities achieved with the compositions of Example 2D (glycerine and borax) and various compositions of Example ?F (borax and carboxylic acid compound) and of Example 2G (formulated in accordance with the invention) is setforth below in Table4.

Table 4 Enzyme stability PercentActive EnzymeAfter 7 Days at 'lO"F Example Composition (43" C) 2D (Glycerineborax) 59 2F(1) (Borax/malonicacid) 45 2G (2) (Glycerineborax/malonic acid) 70 2F (2) (Borax/aspartic acid) 72 2G (5) (Glycerineboraxasparticacid) 90 2F(3) (Borax/citric acid) 42 2G (6) (Glycerine/borax/citric acid) 74 Notes on Table 4 2F(1) correspondsto 2G(2); 2F(2) corresponds to 2G(5) and 2F(3) correspondsto 2G(6).

As shown in Table 4, the various compositions of Example 2G(2), 2G(5) and 2G(6) containing a three com- ponent stabilizer system in accordance with the present invention provided a synergistic improvement in enzyme stability relative to the compositions of Examples 2D and 2F(1), 2F(2) and 2F(3)formulated in accordance with the prior art.

Claims (14)

1. A stabilized fabric softening enzyme-containing built liquid detergent composition comprising: (a) from about 5to 20%, by weight, of one or more surface active detergent compounds selected from the group consisting of anionic, nonionic and amphoteric detergentcompounds; (b) from about 5to 30%, by weight, of one or more builder salts selected from the group consisting of alkali metal tripolyphosphates, alkali metal carbonates, alkali metal nitrilotriacetates and polyacetal carboxylates; (c) from about 5 to 20%, by weight, of a swelling bentonite clay; (d) an effective amount of an enzyme or an enzyme mixture selected from the group consisting of alkaline protease enzymes and alpha-amylase enzymes;; (e) an enzyme-stabilizing system containing, based on the weight of the detergent composition, (i) from about 1% to 10% glycerine; (ii) from about 1 to 8% of a boron compound selected from the group consisting of boric acid, boric oxide and alkali metal borates; and (iii) from about 0.5 to 8% of a carboxylic acid compound selected from the group consisting of mono, di and/or polycarboxylic acids having 1 to 8 carbon atoms and water-soluble salts thereof; and (f) the balance comprising water and optionally perfume and otheradjuvants.

2. A liquid detergent composition as claimed in Claim 1 comprising: (a)from about5to 15% ofan alkali metal alkylbenzenesulphonate in which the alkyl group contains 12to 15 carbon atoms; (b)from about2to 5% ofan alkali metal alkyl polyethoxysulphate in which the alkyl group contains lOto 18 carbon atoms and the polyethoxy is of3 to 11 ethylene oxide groups, the weight ratio of (a) to (b) being from about 2:1 to about 8:1; (c) from about 5 to 20% of sodium tripolyphosphate; (d)from about 1 to 10% of sodium carbonate, the weight ratio of (c) to (d) being from about 2:1 to about6::1, (e)from about 10to 15% ofa sodium bentonite; (f) an effective amount of the said enzyme or enzyme mixture; (g) the enzyme stabilizing system containing, based on the weight ofthe detergent composition, (i) from about3to 7% glycerine, (ii)from about 1 to 5% of an alkali metal borate and (iii)from about 0.5to 4% ofthe said carboxylic acid compound; and (h) the balance comprising water and optionally minoradjuvants.

3. A liquid detergent composition as claimed in Claim 1 or Claim 2 in which the said alkali metal alkylbenzene sulphonate is sodium lineartridecylbenzene sulphonate and the said alkali metal alkyl polyethoxy sulphate is one in which the alkali metal is sodium, the alkyl group contains 12 to 15 carbon atoms and the polyethoxy is of about 3 ethylene oxide groups.

4. A liquid detergent composition as claimed in Claim 2 or Claim 3 in which the ratio of alkylbenzene sulphonateto polyethoxy sulphate is from about 2:1 to about 4:1.

5. A liquid detergent composition as claimed in any one of Claims 1 to 4 in which the said boron compound is an alkali metal borate.

6. A liquid detergent composition as claimed in Claim 5 in which the said borate is borax.

7. A liquid detergent composition as claimed in any one of Claims 2 to 6which contains from about8to 16% sodium tripolyphosphate and from about 2to 6% sodium carbonate, sodium bicarbonate or mixtures thereof.

8. A liquid detergent composition as claimed in any one of Claims 1 to 7 in which the said carboxylicacid compound is aspartic acid or a water-soluble saltthereof.

9. A liquid detergent composition as claimed in any one of Claims 1 to 7 in which the said carboxylicacid compound is tartaric acid our a water-soluble saltthereof.

10. A liquid detergent composition as claimed in any one of Claims 1 to 7 in which the said carboxylicacid compound is citric acid orawater-solublesaltthereof.

11. A liquid detergent composition as claimed in any one of Claims 1 to 7 in which the said carboxylicacid compound is malonic acid or a water-soluble salt thereof.

12. A liquid detergent composition as claimed in any one of Claims 1 to 7 in which the said carboxylicacid compound is malic acid or a water-soluble salt thereof.

13. A liquid detergent composition as claimed in Claim 1 substantially as specifically described herein with reference to anyone of Examples 1 or Examples 2G(1 ) to 2G(8).

14. A method of laundering comprising contacting the stained and/or soiled fabricsto be laundered with a stabilized enzyme-containing built liquid detergent composition as claimed in anyone of Claims 1 to 13.