WO1999033942A1

WO1999033942A1 - Detergent composition having improved cleaning power

Info

Publication number: WO1999033942A1
Application number: PCT/US1998/027158
Authority: WO
Inventors: Hoai-Chau Cao; Marie-Christine Houben; Patricia Pagnoul
Original assignee: Colgate-Palmolive Company
Priority date: 1997-12-29
Filing date: 1998-12-21
Publication date: 1999-07-08
Also published as: AU1935799A

Abstract

Detergent compositions which are formulated for use in wash water at a pH of 7.5 and below are disclosed. The compositions contain at least one anionic surfactant and optional builders and enzymes, and also contain at least one water soluble organic polymer, such as polyethylene glycol, which is miscible with or soluble in the surfactant. The presence of the water soluble polymer leads to enhanced fabric cleaning performance in an acidic to near basic wash medium.

Description

DETERGENT COMPOSITION HAVING IMPROVED CLEANING POWER

Field of the Invention

This invention relates to detergent compositions

Description of Related Art

Detergent compositions, particularly liquid laundry and/or dishwasher detergents, are generally formulated to contain one or more anionic surfactant materials, builder materials, electrolyte materials and other adjuvants dispersed or dissolved in an aqueous medium. They are generally formulated at an alkaline pH of above 7, e.g., 8-12, and generally contain buffer ingredients and/or builder materials which will maintain an alkaline pH in both the detergent composition if it is a liquid, and in the wash water to which the detergent composition is added.

The main reason for the development of basic pH is to insure that the anionic surfactant components, enzymes or other organic components present in the composition remain solubilized and dispersed in the wash water and that greasy or oily stains removed from soiled clothing are also dispersed in the wash water.

An example of a liquid detergent composition is found in U.S. Patent 5,108,644 which discloses a liquid detergent concentrate comprising a mixture of nonionic polyalkoxy-lated anionic surfactants, a salting out electrolyte/ builder and a water soluble, viscosity reducing polymer which may be a polyethylene glycol. The composition is formulated to have an alkaline pH of around 11, as shown in Table II.

Although the use of an alkaline medium can facilitate the performance of anionic surfactants and greasy stain removal, such a medium can have an adverse effect on fabrics, mainly cotton, wool and mixed fiber fabrics, after cumulative washes. Examples of such adverse effects are fabric damage caused by alkaline hydrolysis of plant fibers such as cotton, rayon or linen, deterioration of delicate animal fibers such as wool, silk, cashmere, mohair and alpaca, and also solubilization and removal of color printing dyes from natural and synthetic fibers. These fabric damages are perceived by the consumer as one or more of a loss of shape, shrinkage, pilling, felting, color fading and dye transfer.

Despite these negative effects, heavy duty detergents containing anionic surfactants are generally formulated to deliver a wash water pH above about 7.5 because poorer cleaning performance is observed where the wash water is acidic to near neutral pH. The very weak cleaning performance at lower pH is due primarily to low solubility, and thus less efficacy of anionic surfactants which are not completely neutralized, poor neutralization and therefore less solubilization of fatty and greasy soils present in soiled fabrics, low enzyme performance for removal of biologically degradable stains and high risk of soil redeposition.

There are detergent compositions which can be adapted for use at neutral or near neutral pH, but these generally have low cleaning performance and are formulated mainly as fine fabric compositions to refresh the fabric and remove light soils. They are generally formulated using mild non- ionic surfactants and may contain an enzyme to facilitate removal of biodegradable stains. For example, U.S. Patent 3,819,528 discloses aqueous enzyme-containing compositions comprising water, an amylolytic enzyme, a water soluble calcium salt present as an enzyme stabilizing agent, an aliphatic glycol present as a co-stabilizing agent for the enzyme and an optional non- ionic or zwitterionic detergent. The composition is adjusted to a pH of from about 5.0 to 10.0, more preferably from about 6.5 to 8.5.

In addition, U.S. Patent 3,860,536 discloses an enzyme/detergent composition comprising an aqueous solution of a protease enzyme, a surfactant material and a polyhydric alcohol which serves to stabilize the composition at a pH in the range of about 6 to 9.5.

There remains a need in the detergent industry to provide a heavy duty detergent which can provide the cleaning performance at least equal to conventional heavy duty detergents containing anionic surfactant, but which are formulated to provide an acidic to near neutral pH in the wash water, thereby minimizing fabric damage.

SUMMARY OF THE INVENTION

The present invention provides detergent compositions comprising a mixture of:

a) at least about 5 wt% of a surfactant comprising one or more anionic surfactants; said detergent composition being free of a quaternary nitrogen- containing cationic compound;

b) from 0 up to about 40 wt% of at least one detergent builder;

c) from 0 up to about 5 wt% of at least one enzyme; and

d) at least about 0.1 wt% of a water soluble organic polymer which is miscible with or soluble in said surfactant; said composition generating a wash water pH in the range of about 5 to 7.5 when diluted with wash water at a concentration sufficient to provide effective cleaning performance and wherein the cleaning performance provided by the detergent composition in the wash bath is superior to that provided by an otherwise identical detergent composition which is free of said water soluble organic polymer.

The invention also provides for a method for washing fabrics comprising forming a dilute aqueous solution of the detergent composition described above such that a wash water pH in the range of from about 5 to 7.5 is developed in the wash water and subjecting fabric material to washing action in said wash water.

The detergent of the invention provides improved fabric cleaning performance at a pH of up to 7.5 when used to wash stained natural or synthetic fabrics. This cleaning performance is accompanied by a reduction in fabric damage which may normally be found after cumulative washings in conventional detergent compositions formulated to provide a more alkaline wash water.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 and Fig. 2 are graphs depicting the degree of removal of various stains from fabric using a conventional washing detergent as compared with acidic washing detergents with and without the water soluble organic polymer component of this invention.

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, the detergent compositions of the invention containing anionic surfactant and formulated to an acid to near neutral pH provide equal or superior fabric cleaning performance when compared with conventional formulations which need to be formulated to provide a more alkaline pH in order to provide acceptable fabric cleaning performance. The key to improved performance in more acidic wash mediums in accordance with this invention is the presence in the detergent composition of a water soluble organic polymer which is miscible with or soluble in the anionic surfactant and is also miscible with optional enzymes which may be present in the composition. Although the water soluble polymers are not themselves known as active cleaning agents, these polymer molecules have an affinity for both the active ingredients and the fabric surface. They thus serve to "link" surfactant and/or enzyme molecules and the fiber surfaces of fabrics being washed, thereby carrying these actives into closer and more intimate contact with such surfaces . In a more acidic medium, the anionic surfactant and enzyme molecules have a much poorer cleaning performance than they do in a basic medium, mainly due to a lessened solubility of the anionic surfactants and a lessened activity of commercially available alkaline enzymes, designed to be active at a pH of above about 7.5, in an acidic washing medium. The present invention overcomes this poor cleaning performance in an acid to near neutral pH wash medium and provides the advantages of good detergent/enzyme cleaning power and reduced fabric damage brought about by cumulative washings in an alkaline wash medium. The term "near neutral pH" as used herein encompasses a pH of 7.0 ± 0.5.

Although the exact mechanism by which the water soluble organic polymers improve cleaning performance of fabric in an acidic to near neutral wash medium is not precisely known, it is believed that these polymers form hydrogen bonds by electron resonance involving oxygen atoms and/or hydroxyl groups present in the linker polymer and the hydrogen present in the non-neutralized acidic functionalities of the surfactants and enzymes, as well as with ether functionalities which may be present in alkoxylated surfactants. In turn, linker polymers containing oxygen in the polymer structure tend to similarly form hydrogen bonds with hydroxyl or other polar functional groups present in the fabric being washed, e.g., hydroxyl groups present in the glucose structure of cotton or rayon fibers. This hydrogen bonding effect occurs primarily at an acidic or near neutral pH and occurs to a much lesser extent, if at all, at a more basic pH because of neutralization of the anionic functionalities of the surfactants and/or enzymes at basic pH.

Thus, the water soluble organic polymers useful in the present invention are those which are capable of forming hydrogen bonds with the surfactants and/or enzymes present in the detergent composition at an acidic or near neutral pH. Such polymers include polyvinyl alcohols, polysaccharides, polyalkylene glycols, vinyl pyrrolidone polymers and like materials containing hydroxyl, ether and/or anhydride functionalities.

Preferred organic polymers which are both water soluble and are miscible with or soluble in anionic surfactants include polyethylene glycol, polypropylene glycol and mixtures thereof having a molecular weight in the range of from about 200 to 20,000, preferably from about 500 to 10,000 and most preferably from about 500 to 5,000. Other preferred polymers include vinylpyrrolidone polymers, which includes polyvinylpyrrolidone as well as water soluble copolymers of vinylpyrrolidone with up to 50 mole % of copolymerizable unsaturated hydrophilic monomers such as acrylic monomers. The molecular weight of the vinyl pyrrolidone polymers may range from about 4,000 to 200,000, more preferably from about 10,000 to 50,000.

The organic polymer is present in the composition in an amount sufficient to enhance the cleaning performance of the detergent composition at an acid or near neutral pH, generally at a level of from about 0.1 to about 5 wt%, more preferably at a level of from about 0.25 to 2.5 wt%.

The detergent composition also contains at least about 5 wt% of one or a mixture of anionic surfactants and may also contain a mixture of anionic surfactant with non- ionic, cationic or amphoteric surfactants .

Suitable anionic surfactants include the water-soluble alkali metal salts 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 (Cg-Ciβ) alcohols produced, for example, from tallow or coconut oil; sodium and potassium alkyl (C₉-C₂₀) benzene sulfonates, particularly sodium linear secondary alkyl (C₁₀-C₁₅) benzene sulfonates; sodium alkyl glycerol ether sulfates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulfates and sulfonates; sodium and potassium salts of sulfuric 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 neutralized with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyl taurine; alkane monosulfonates such as those derived from reacting alpha-olefins (C₈-C₂₀) with sodium bisulfite and those derived from reacting paraffins with S0₂ and Cl₂ and then hydrolyzing with a base to produce a random sulfonate; and olefin sulfonates which term is used to describe the material made by reacting olefins, particularly C₁₀-C₂₀ alpha-olefins, with SO₃ and then neutralizing and hydrolyzing the reaction product. The preferred anionic surfactants are (Cio-Cis) alkyl polyethoxy (1-11 Eo) sulfates and mixtures thereof having differing water solubilities.

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 and alkyl phenols with alkylene oxides, especially ethylene oxide, either alone or with propylene oxide. Specific nonionic surfactant compounds are alkyl (C₆-Cιg) primary or secondary linear or branched alcohols condensed with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic surfactant compounds include long chain tertiary amine oxides, long-chain tertiary phosphine oxides, dialkyl sulfoxides, fatty (Cs-Cig) esters of glycerol, sorbitan and the like, alkyl polyglycosides, ethoxylated glycerol esters, ethyoxylated sorbitans and ethoxylated phosphate esters .

The preferred non- ionic surfactant compounds are those of the ethoxylated and mixed ethyoxylated-propyloxylated (Cg-Cis) fatty alcohol type, containing 2-11 EO groups.

Examples of amphoteric surfactants which can be used in the compositions of the present invention are betaines and those which can be broadly described as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Examples of compounds falling within this definition are sodium 3-dodecylaminopropionate, sodium 3-dodecylaminopropane sulfonate, N-alkyltaurines, such as prepared by reacting dodecylamine with sodium isothionate, N- igher alkyl aspartic acids and the products sold under the trade name "Miranol".

Examples of betaines useful herein include the high alkyl betaines such as coco dimethyl carboxymethyl betaine, lauryl dimethyl carboxymethyl betaine, lauryl dimethyl alpha- carboxymethyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis (2-hydroxyethyl) carboxy methyl betaine, stearyl bis- (2-hydroxypropyl) carboxymethyl betaine, oleyl dimethyl gamma- carboxypropyl betaine, lauryl bis- (2-hydroxypropyl) alpha- carboxymethyl betaine, etc. The sulfo-betaines may be represented by coco dimethyl sulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, lauryl bis- (2-hydroxyethyl) sulfopropyl betaine, amino betaine amidosulfobetaines, and the like.

Other suitable betaines include 1- (lauryl, dimethylammonio) acetate- 1- (myristyl dimethylammonio) propane-3 -sulfonate, 1- (myristyl dimethylamino) -2 -hydroxypropane-3 -sulfonate, cocoamidoethylbetaine and cocoamidopropylbetaine .

A more detailed illustration of the various surfactants and classes of surfactants mentioned may be found in the text Surface Active Agents, Vol. II, by Schwartz, Perry and Berch (Interscience Publishers, 1958) , in a series of annual publications entitled McCutcheon's Detergents and Emulsifiers, issued in 1969, or in Tenside-Taschenbuch. H. Stache, 2nd Ed. Carl Hanser Verlag, Munich and Vienna, 1981.

The anionic surfactant or mixture of surfactants may be present in the composition at a level of from about 5 to 75 wt%, more preferably from about 5 to 35 wt% where the detergent is in liquid form. Where a mixture of anionic and non-anionic surfactants are used, the mixture preferably contains at least about 40 wt% of the anionic surfactant.

The composition may also contain one or more detergency builders. The selection of particular builders from those known in the art is dictated by the fact that it is preferably not be a material that will generate a significantly basic pH above about 7.5, preferably not above 7.0, in the wash water, or in the detergent composition itself if it is in the form of a liquid, or at least is preferably not present in the detergent composition at levels high enough to generate such a pH. Thus known builders such as Zeolites are less preferred as the main builder component because of proton exchange from the acidic detergent medium with the alkali metal, e.g., sodium cation, of the zeolite after a period of storage. Other builders which are less preferred as the main builder component include the alkali metal carbonates, bicarbonates, phosphates and silicates, since these materials also generate a more basic pH in an aqueous medium.

Preferred builders include organic builders, for example, polycarboxylate builders, such as aminopolycarboxylates , for example, sodium and potassium ethylene-diamine tetraacetate; sodium and potassium nitrotriacetate; and the polyacetal polycarboxylates , such as those described, for example, in U.S. Patent Nos. 4,144,226 and 4,315,092. Other organic builders of the polycarboxylate type include the water-soluble salts, especially sodium and potassium salts, of mellitic acid, citric acid, pyromellitic acid, benzene polycarboxylic acids, carboxymethyloxy succinic acid, cis-cyclohexane hexacarboxylic acid, and the like. Citric acid salt, e.g., potassium or sodium citrate, is often a preferred builder in non-phosphate or low phosphate formulations. In liquid detergent compositions, the citric acid salt also serves a dual function as a builder and an electrolyte which helps maintain the surfactant micelles dispersed in the aqueous liquid medium.

This is not to say that conventional builders which tend to generate a basic pH in aqueous medium cannot be used, particularly in granular or powder detergents. Such builders include phosphates such as sodium polyphosphate, and alkali or alkaline earth metal silicates, carbonates, and bicarbonates, as well as zeolites and like well known builders. However, when such builders are used, there may be a need to also include an amount of a weak acid in the formulation sufficient to lower the pH of the liquid detergent and the pH of the wash water to the required acidic to near-neutral range. Suitable such acids include mono or polycarboxylic acids such as citric acid, acetic acid, adipic acid, succinic acid, glutaric acid and the like, as well as mixtures thereof.

Where present, the builder is used at generally low levels of from about 1 to about 40 wt% of the detergent composition, more preferably from about 1 to 20 wt% of said composition.

The detergent composition may also contain one or more enzymes which are active against biodegradable stains, e.g., starches, vegetable and blood, and which are also active at a pH of about 5 to about 12, more preferably at a pH of 7 or below. Indeed, one of the main advantages of the present invention is that enzymes which are generally not active at a wash water pH of below about 7.5 are made to be active at a lower pH because the presence of the water soluble polymer component, which serves to enhance the performance of enzymes in an acidic medium in a manner analagous to enhancement of surfactant performance as described above. Preferred enzymes which may be used include amylolytic enzymes (alpha amylases) , alkaline and neutral proteases, lipolases, cellulases and the like, and mixtures thereof .

Alkaline or neutral proteolytic enzymes suitable for the present composition 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 a built liquid detergent composition. Thus, suitable liquid enzyme preparations include "Alcalase" and "Savinase", trademarked products sold by Novo Industries, Copenhagen, Denmark, and "Maxatase", "Maxacal", "Maxaperm" and "AZ-Protease" sold by Gist-Brocades, Delft, The Netherlands. Low pH active enzymes such as Alcalase and Maxatase are preferred as compared with enzymes active at a pH above 7.5.

Other suitable alpha-amylase liquid enzyme preparations are those sold by Novo Industries and Gist-Brocades under the tradenames "Termamyl" and "Maxamyl", respectively. Another enzyme preparation which may be used is a powdered enzyme preparation containing alpha-amylase and a mixture of alkaline and neutral proteases available as CRD-Protease from the Monsanto Co of St. Louis, Missouri.

Where used, the enzymes are normally present in the detergent composition at a level of from about 0.01 up to about 5 wt%, more preferably from about 0.1 to 2 wt% .

The composition may also contain a suitable stabilizer system for the enzyme such as up to 1 wt% calcium chloride or the combination of boric acid, boric oxide or alkali metal borate and water soluble calcium salt as disclosed in U.S. Patent 5,364,533.

An optional, but often preferred additive, is a higher fatty acid, which may be saturated or unsaturated, and may contain from about 10 to about 22 carbon atoms, preferably from about 12 to 20 carbon atoms. Oleic acid is especially preferred in amounts of from 0.1 to about 10% by weight of the composition. These higher fatty acids function in the detergent compositions as anti- foaming agents and also function as soap surfactants in combination with neutralizing cations, e.g., sodium or potassium, present in the composition. They may be used alone for this anti-foaming function but are often used in combination with polysiloxane (silicone) anti- foaming agents. The silicone anti-foaming agents will generally be present in minor amounts compared to the fatty acid. Suitable ratios (by weight) of the fatty acid anti- foaming agent to silicone anti- foaming agent may range from about 100:1 to 1:10, preferably 50:1 to 1:1, especially 30:1 to 2:1.

The detergent composition may also contain one or more softening components known in the art. For reasons discussed above, preferred softeners are those materials which will not generate a basic wash water pH or materials which are not present in the composition at levels sufficient to generate a basic pH above 7.5, preferably not above 7.0. Suitable softeners include swelling bentonite clays such as sodium and calcium montmorillonites, sodium saponites and sodium hectorites. These may be present in the detergent composition at levels of from about 0.5 to 20wt%, more preferably from about 5 to 15 wt% .

Other conventional materials may also be present in the liquid detergent compositions of the invention, for example, soil- suspending agents, thickening agents, sequesterants such as salts of ethylene diamine tetraacetic acid or analogous phosphonic acid salts, hydrotropes, corrosion inhibitors, dyes, perfumes, optical brighteners, suds boosters, germicides, e.g., quaternary ammonium salts, preservatives, e.g., quaternium 15, anti-tarnishing agents, opacifiers, oxygen-liberating bleaches such as sodium perborate or percarbonate with or without bleach precursors, buffers and the like. Such other conventional materials may be used in the amounts they are normally used generally up to about 5% by weight, more preferably up to about 3% by weight, although higher amounts which do not interfere with the stability of the composition or give rise to an unacceptably high pH may be used, if desired. The detergent compositions of the present invention may be in liquid or in granular form. The liquid carrier for the liquid compositions of this invention is preferably water alone, but an aqueous carrier containing minor amounts of a lower alcohol, such as ethanol or isopropanol, may also be used in some cases. Generally, water levels may be up to about 90% by weight of the composition, for example, from about 20% to about 90%, preferably from about 20% to 70%, by weight. The water may be deionized, but usually tap water is sufficient.

The viscosity of the liquid detergent is normally in the range of about 800 to 10,000 centipoises, preferably 2,000-7,000 centipoises, but products of other suitable viscosities may also be useful. At the viscosities mentioned, the liquid detergent is pourable, stable, nonseparating and uniform.

As necessary, pH modifiers, such as water soluble bases, e.g., NaOH, KOH, amines, or ammonia, will be added to obtain the desired pH level. The preferred pH will range from about 5 up to 7.5, more preferably from about 5.0 up to less than 7.0 and most preferably from about 5.5 up to 6.9. Where the detergent composition is in the form of a liquid, the liquid will also exhibit a pH within these specified ranges.

Powder or granular forms of the detergent composition may be prepared by conventional granulation techniques, such as spray drying, wherein a liquid formulation (crutcher slurry) is spray dried and the resulting granular product collected. The crutcher slurry also preferably will contain one or a mixture of granulation aids such as sodium sulfate, silicates, clays and other well known material as such as disclosed in U.S. Patents 5024778 and 5332513. The amount of such granulation aids will generally range from about 10 to 50 wt%. The water content of such granular detergents generally ranges from about 5 to 15 wt%.

The detergent compositions of this invention are suitable for use as laundry detergents, dish washer detergents, shampoos, body lotions and the like and may be modified by inclusion of specific known ingredients to accommodate these applications, e.g., dispersing agents, skin conditioning agents, anti- dandruff agents and the like.

Conventional manufacturing methods may be used to formulate the liquid detergent composition. In one procedure, a portion of the aqueous medium may be added to a mixing vessel and the surfactant components may be mixed therewith in any suitable order, followed by addition of builder, acidic components and sufficient neutralizing base, e.g., KOH, to produce the desired pH. Softeners, enzyme, water soluble polymer, minors, e.g., perfume, optical brighteners, foam control agents, and the balance of water may then be added and mixing continued to form an aqueous dispersion. Granular forms of the detergent may be prepared by spray drying a liquid formulation to a water content of up to about 15 wt%, followed by the addition of any volatiles after spray dry processing.

The detergents of the invention are generally added to wash water at levels in the range of about 0.05 to 0.30 wt%. For conventional washing machines, detergents in the form of liquids are preferably added at levels in the range of from about 60 to 240 ml per load; powder detergents are preferably used at levels of about 60 to 300 grams per load.

The following examples are illustrative of the invention.

Example 1

Three different liquid detergent formulations were prepared having a composition of main ingredients, by weight, as shown in Table 1. Formulation A is typical of a conventional detergent formulation containing zeolite builder, clay softener and formulated to a pH of about 8.2. Formulation B is free of Zeolite builder and contains citric acid (neutralized to potassium citrate) and is adjusted to a pH of about 6.0. Formulation C is within the present invention and is similar to Formulation B except that it contains a water soluble polyethylene glycol polymer having a molecular weight of about 4000 (PEG 4000) . Ingredients were mixed in the order shown in Table 1.

TABLE 1

* AEOS - C₁₂ -C₁₄ fatty alcohol ether sulfate (3EO) .

NI-3EO - CJ₂ -C₁₄ fatty alcohol containing 3 ethylene oxide (EO) groups.

Durazym™ 16L - Protease enzyme from Novo Industries

Alcalase™ 2.5L - Protease enzyme from Novo Industries

Dequest™ 2066 - Sodium salt of diethylene-triamine- pentamethylene phosphonic acid from Monsanto Chem. Co.

Both prototypes B and C are formulated at a slightly acid pH (pH=6) compared to the conventional liquid made in an alkaline medium (pH=8.2) . The difference between prototypes B and C is the presence of 0.7 wt% of the polymer linker in C.

All products were tested in a European tumble type front loading washing machine (MIELE™) at 40°C and at a 200ppm CaC0₃ water hardness at a dosage level of about 180 ml. of liquid per load. Figs. 1 and 2 show respectively the greasy (sensitive to surfactants) and the bio-stains (sensitive to enzymes) removal performance of these products . The detergency expresses the difference (Δ Rd) between the reflectance Rd before washing and the reflectance Rd after washing. The term "Krefeld" refers to an artificial, particulate soiled cotton fabric (code WFK 10c) supplied by wfK-Testgewebe G bh of Germany.

In Fig. 1, it can be observed that the cleaning performance of the surfactants of formulation B on greasy stain is significantly lower compared to the commercial product A having alkaline pH. The incorporation of 0.7% PEG 4000 as in formulation C recovers back the greasy cleaning performance of this new acidic detergent due to the linker effect of the polymer.

Figure 2 shows the cleaning performances of enzyme sensitive stains between the conventional product A and the detergent of the invention (C) . It can be observed that, due to the inappropriate medium - low pH - the enzymes in formulation B are not fully active resulting in a strong drop of soil removal performance on all stains: cocoa, groundnut/milk and blood/milk/ink. The incorporation of 0.7% PEG 4000 as in formulation C again corrects this tremendous weakness.

These results evidence that the PEG polymer linker not only can bind with conventional molecules such as surfactants and bring them close to the fabric surface, but can "link" also unconventional complex molecules such as enzymes.

Example 2

Three different powder formulations were mixed in the laboratory and had a composition of main ingredients, by weight, as shown in Table 2. Formulation D is typical of a conventional powder formulation containing anionic surfactant (LAS) , builder (STPP) enzyme and granulation aid (sodium sulfate) , which is formulated to provide an alkaline pH in the wash water. Formulation E is similar to D except that it contains "SOKALAN" DCS from BASF corporation, which is a powdered mixture of adipic, glutaric and succinic acids, added to impart an acidic wash water pH after the powder is dispersed in the wash water medium. Formulation F is within the scope of the present invention and is similar to Formulation E except that it also contains the polyethylene glycol linker polymer. The ingredients were mixed in the order shown in Table 2.

TABLE 2

*LAS - C₁₃-C₁₅ alkyl benzene sulfonate surfactant STPP - sodium tripolyphosphate builder

Cleaning performance of each product with respect to removal of bio and greasy stains from soiled cotton fabric was evaluated by washings in the Miele™ machine as described in Example 1 except the powder dosage level was 100 grams per washing. The detergency efficiency (ΔRd) was measured as an Example 1 for each product before and after the wash and results are shown in Table 3. TABLE 3

These results demonstrate improved performance of the powder containing the linker polymer mainly with respect to bio stain removal in the slightly acidic medium even where an alkaline active enzyme issued. The performance of the surfactant is also significantly improved with respect to the removal of skin soils.

Claims

CLAIMSWhat is claimed:

1. A detergent composition comprising a mixture of:

b) from 0 up to about 40 wt% of at least one detergent builder;

c) from 0 up to about 5 wt% of at least one enzyme; and

2. The composition of claim 1 wherein said water soluble organic polymer is present at a level of up to about 5 wt%.

3. The composition of claim 2 wherein said water soluble organic polymer comprises a glycol selected from the group consisting of polyethylene glycol, polypropylene glycol and mixtures thereof having a molecular weight in the range of from about 200 to 20,000.

4. The composition of claim 3 wherein said glycol has a molecular weight in the range of about 200 to 6,000.

5. The composition of claim 3 wherein said water soluble organic polymer is polyethylene glycol .

6. The composition of claim 2 wherein said water soluble organic polymer comprises a vinylpyrrolidone polymer.

7. The composition of claim 1 containing from about 5 to 35 wt% of said surfactant.

8. The composition of claim 1 containing at least about 1 wt% of said builder.

9. The composition of claim 8 wherein said builder is characterized as producing a pH not greater than 7.5 after dilution with water.

10. The composition of claim 9 wherein said builder is characterized as prodcuing a pH below 7.0 after dilution with water.

11. The composition of claim 9 wherein said builder is an alkali metal polycarboxylate.

12. The composition of claim 11 wherein said builder is sodium or potassium citrate.

13. The composition of claim 1 containing at least 0.01 wt% of said enzyme.

14. The composition of claim 1 further containing from about 0.1 to about 10 wt% of at least one fatty acid containing from about 10 to 22 carbon atoms.

15. The composition of claim 14 wherein said fatty acid is oleic acid.

16. The composition of claim 1 wherein said detergent is in the form of a liquid and contains at least about 20 wt% water.

17. The composition of claim 16 wherein said liquid detergent contains from about 20 to 70 wt% water.

18. The composition of claim 16 wherein said liquid detergent has a pH in the range of from about 5 to 7.5.

19. The composition of claim 18 wherein said liquid has a pH of less than 7.0.

20. The composition of claim 16 wherein said liquid contains at least 0.01 wt% of said enzyme.

21. The composition of claim 19 wherein the pH of said detergent composition ranges from about 5.5 up to 6.9.

22. The composition of claim 1 wherein said detergent is in granular form.

23. The composition of claim 22 which contains at least 0.01 wt% of said enzyme.

24. The composition of claim 1 wherein said anionic surfactant comprises an alkali metal salt of an alkyl polyethoxy sulfate wherein the alkyl group contains from about 8 to 22 carbon atoms and the polyethoxy is of 1 to 11 ethylene oxide groups .

25. The composition of claim l wherein said water soluble organic polymer is capable of forming hydrogen bonds with the surfactant and enzyme present in said composition at an acidic to near neutral pH.

26. The composition of claim 1 wherein said wash water pH ranges from about 5 to less than 7.0.

27. The composition of claim 26 wherein said wash water pH ranges from 5.5 to 6.9.

28. A liquid detergent composition comprising a mixture of:

a) from about 5 to 35 wt% of one or more anionic surfactants;

b) from about 0.25 up to 2.5 wt% of polyethyleneglycol;

c) from about 1 to 20 wt% of sodium or potassium citrate;

d) from about 0.1 to about 2 wt% of an enzyme selected from amylolytic enzymes, alkaline and neutral proteases, and mixtures thereof; and

e) from about 20 to 70 wt% water;

said composition characterized by a pH of from about 5 to less than 7.

29. A method for washing fabrics comprising forming a dilute aqueous solution of the detergent composition of claim 1 such that a wash water pH in the range of from about 5 to 7.5 is developed and subjecting fabric material to washing action in said wash water.

30. The method of claim 29 wherein a pH in the range of about 5 to 6.9 is developed in said wash water.

31. The method of claim 29 wherein said detergent composition contains at least 0.01 wt% of said enzyme.

32. The method of claim 31 wherein said detergent composition contains at least about 1 wt% of said builder.

33. The method of claim 31 wherein said water soluble organic polymer is present in said detergent composition at a level of up to about 5 wt%.

34. The method of claim 29 wherein said detergent composition is in the form of a liquid containing at least about 20 wt% water.

35. The method of claim 34 wherein said detergent contains from about 20 to 70 wt% water.

36. The method of claim 29 wherein said detergent composition is in the form of a powder containing less than 15 wt% water.