GB2131826A - Liquid detergent composition with mixed enzyme formulation - Google Patents

Abstract

Enzyme-containing liquid detergent compositions are provided comprising: (a) 5 to 75% of one or more detergent surface active agents, preferably 10 to 60% of a C2-C3 alkoxylated C10-C18 alkanol nonionic detergent compound; (b) from 25 to 85% water; and (c) an enzyme mixture consisting essentially of an alkaline protease enzyme and an ???-amylase enzyme in relative proportions such that the ratio of the enzyme activities in the mixture is from about 4,000 to about 80,000 Novo amylase units of ???-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 100 grams of detergent composition. a

Description

SPECIFICATION Liquid detergent composition with mixed enzyme formulation This invention relates, in general, to enzyme-containing liquid detergent compositions which are suitable for laundering or pre-soak formulations. More particularly, the invention relates to detergent compositions containing mixtures of protease and amylase enzymes in defined proportions which provide particularly effective soil and stain removal during laundering.

The formulation of enzyme-containing liquid detergent compositions has been the focus of such 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 the most expensive ingredients in a typcial commercial liquid detergent composition, even when present in relatively minor amounts. Moreover, an excess of enzymes is generally required in the detergent formulation.Because of the known instability of enzymes in aqueous compositions an excess of enzymes is generally added to the formulation to compensate for the expected loss of enzyme activity during prolonged periods of storage. Consequently, the expense associated with the use of enzymes in liquid detergent compositions has heretofore been a significant detergent to their widespread commercial use.

Detergent compositions containing mixtures of enzymes, e.g. proteases and amylases, have been broadly described in the prior art. Thus, for example, U.S. Patent 3,630,930 describes a granular detergent composition containing from about 0.5 to 20% of enzyme carrier granules, the enzyme granules comprising from about 0.001 to 10% of mixtures of protease and amylase enzymes in a weight ratio of protease to amylase of 50:1 to 1:5. British Patent Specification No. 1,240,058 discloses a granular detergent composition containing a mixture of protease and amylase enzymes in a weight ratio of protease to anylase of 30:1 to 3:1, the weight percent of amylase in the composition being from 0.0003 to 3%. In U.S.Patent 3,931 ,034 to Inamorato et a/ there is disclosed a granular detergent composition containing a mixture of alkaline protease and a-amylase enzymes in a ratio of activity varying from 100,000 to 400,000 Novo amylase units of amylase per Anson unit of protease.

Accordingly, while the use of enzyme mixtures in granular detergent compositions is generally disclosed in the patent literature, the mixtures themselves are, in most instances, so broadly described as to encompass, for example, mixtures wherein the percent protease may vary within 5 orders of magnitude (British Patent 1240058), or the percent amylase may vary within 5 orders of magnitude (U.S. Patent 3,630,930), thereby encouraging the belief that within such broad ranges, the greater the amount of enzyme used, the more effective the resultant stain removal. In addition, the aforementioned patents, in common with the Inamorato et al patent are strictly related to granular compositions and hence provide no teaching regarding the use of enzyme mixtures in liquid compositions.

In its broadest aspect, the present invention provides a liquid detergent composition comprising a detergent and an enzyme mixture comprising an alkaline protease enzyme and an amylase enzyme in relative proportions such that the ratio of the respective enzyme activities in the mixture is from about 4,000 to about 80,000 Novo amylase units of a-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 100 grams of detergent composition.

In a preferred aspect, the present invention provides an enzyme-containing liquid detergent composition comprising: (a) from about 5 to about 75%, by weight, of one or more detergent surface active agents, which may be anionic, nonionic, cationic, ampholytic or zwitterionic detergent compounds; (b) from about 25 to 85% water; and (c) an enzyme mixture consisting essentially of an alkaline protease enzyme and an amylase enzyme in relative proportions such that the ratio of the enzyme activities is from about 4,000 to about 80,000 Novo amylase units of cr-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 100 grams of detergent compositions.

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

The present invention is based on the discovery that the amount of alkaline protease enzyme which is ordinarily necessary for the removal of proteinaceous stain can be significantly reduced by the combination therewith of an amount of amylase enzyme in accordance with the invention so as to provide a detergent composition having equivalent or improved stain removal capabilities but at a considerably reduced formulation expense. Unlike the disclosures in the art which recommend mixing proteases and amylases over broad ranges in detergent compositions, the enzyme mixtures herein described are characterised by a synergistic interaction of protease and amylase, and encompass only those mixtures having a narrowly defined ratio of activities.

The activities of the alkaline protease and amylase enzymes are expressed in Anson units of protease, and Novo amylase units of amylase, respectively. These are units commonly used in the art to describe the activity, under common conditions, of enzyme formulations containing protease or amylase enzymes.

In a preferred embodiment of the invention the enzyme mixtures contain relative amounts of alkaline protease and a-amylase to provide from about 10,000 to 50,000 Novo amylase units of - amylase per Anson unit of protease, an activity ratio of from about 1 5,000 to 40,000 being even more preferred and a ratio of from about 30,000 to 40,000 being especially desirable.

The amount of the enzyme mixture present in the liquid detergent composition will, of course, depend to some extent on the amount of the composition which is to be added to the wash solution.

For detergent compositions intended for use at concentrations of about 0.15% in the wash solution of an automatic home laundry machine, a suitable amount of mixture will provide from about 0.25 to about 2.5 Anson units of protease per hundred grams of detergent composition, a ratio of from about 0.5 to 2.0 being preferred, and about 1.5 Anson units/1 00 grams of composition being a particularly preferred protease concentration.

The activity of the alkaline protease enzyme is, as noted above, measured in terms of Anson units.

The Anson haemoglobin method for the measurement of Anson unit activity is a procedure well known in the art for determining the activity of proteolytic enzymes, and is set forth in the "Journal of General Physiology", Volume 22, pages 79-89 (1939), such disclosure being incorporated herein by reference. The modified Anson haemoglobin method may also be used for measuring the proteolytic activity, such modified method being described in the article "Alkali-Resistant Enzyme for Detergents", S. R. Green, Soap and Chemical Specialities, pages 86, 88, 90, 94 and 133, May 1968, which disclosure is incorporated herein by reference.In principle, the method employs the alkaline protease enzyme to digest a denatured haemoglobin substrate at standard conditions in a buffered aqueous medium at the selected pH, and the amount of digested material is determined.by a colour test with phenol reagent.

The activity of the a-amylase enzyme is, as previously noted, measured in terms of Novo amylase units. The standard procedure for the measurement of such Novo units is a modification of the SKB method (Sandstedt, Kneen 8 Blish, Cereal Chemistry 16, 712, (1939)) without addition of betaamylase. In this procedure 20 ml of a buffered starch solution (prepared by the method described below) are measured in a test tube (diameter 24 mm, length 190 mm) and placed in a water thermostat at a temperature of 370C. After a few minutes pre-warming, 10 ml of the amylase solution to be tested (or v ml amylase solution+(10-v) ml water) is added. The contents of the tube are thoroughly mixed and at the same time a stopwatch is started.At appropriate time intervals 1 ml of the reaction mixture is added to 5 ml of a dilute iodine solution (prepared by the method described below), shaken and transferred to a comparison tube, and the colour is compared with the standard colour. If the colour endpoint is reached in less than 10 minutes, a more dilute amylase solution or a smaller volume of amylase solution is used.

As a colourimeter the Hellige Comparator 607 is used with the glass amylase standard. (cf.

Redfern Methods for determination of a-amylase, Cereal Chemistry 24,259, (1947)). The a-amylase activity of the sample may be calculated by using the following formula: 1430xV A= where txaxv A=a-amylase activity in Novo amylase units per gram t=time to reach the colour endpoint (minutes) a=weight of sample in grams V=volume to which the sample is diluted (ml) v=volume of amylase solution used (ml) The factor "1430" is not strictly constant but depends to some degree upon the starch quality used. For exact determinations, the value of the factor should be calculated by means of a commercially available standard amylase preparation with known activity.

The "dilute iodine solution" mentioned above is prepared by dissolving 1 ml of "stock iodine solution" and 20 g of potassium iodide in sufficient water to make 500 ml; the "stock iodine solution" is prepared by dissolving 11 g of iodine crystals and 22 g of potassium iodide in sufficient water to make 500 ml. The "buffered starch solution" mentioned above is prepared as follows: 10 g soluble starch (e.g. Merck, Amylum solubile, Soluble Starch, Erg. B.6) calculated as dry matter is made into a slurry with some water. The slurry is added to about 200 ml of boiling water. When the starch is compietely dissolved, the solution is cooled, transferred to a 1 litre volumetric flask and made up to the mark with water. The starch solution (made by dissolving 9.36 g NaCI, 69.00 g KH2PO4, 4.80 g Na2HPO4 .2 H20 in sufficient water to make 1 litre). Finally the solution is saturated with toluene. The pH of the finished buffered starch solution should be 5.7. The starch solution must be as freshly prepared as possible but can be stored in the refrigerator for not more than 24 hours. Distilled water is used in all cases.

The enzyme activity of protelytic and amylolytic enzyme preparations is ordinarily determined, as a practical matter, without conducting the above-described assay procedures. For the majority of commercially available liquid enzyme preparations containing protease or amylase enzymes, the enzyme activity is provided by the manufacturer and is expressed in Anson units, or Novo amylase units (or units directly proportional thereto). Alternatively, the activity of a given enzyme preparation can be readily determined analytically by a procedure wherein the enzyme reactivity with a protein or starch substrate, as the case may be, is measured at standard conditions and then compared with the reactivity of reference enzyme preparations of known activity.In such analytical procedures, enzyme reactivity may be conveniently expressed as the optical density of a test solution containing the enzyme preparation and the protein or starch substrate when measured at standard conditions: the higher the optical density, the greater the activity.

Suitable alkaline proteolytic enzymes include the various commercial liquid enzyme preparations which have been adapted for use in detergent compositions, enzyme preparations in powdered form being also useful although, as a general rule, less convenient for incorporation into the present 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. "Alcalase" is particularly preferred for the present compositions.

Among the suitable a-amylase liquid enzyme preparations are those sold by Novo Industries and Gist-Brocades under the tradenames "Termamyl" and "Maxamyl", respectively.

An organic solvent is preferably used in combination with water to serve as the solvent for the liquid detergent composition. The preferred organic solvent is a lower alkanol of 1 to 4 carbon atoms having from 1 to 3 hydroxy groups, preferably 1 or 2. The lower alkanol is most preferably ethanol or a mixture of ethanol and isopropanol, with lower monoalcohols such as propanol and butanol, and lower polyols of 2 to 3 carbon atoms such as ethylene glycol and propylene glycol being useful albeit less preferred. The use of primary, secondary and tertiary butanol or n-propanol as the lower alkanol is generally restricted to being in mixtures with ethanol, ethanol constituting preferably at least 80 to 90% of such mixtures. It is highly preferred to use ethanol as the sole alkanol and organic solvent.In mixtures of ethanol and isopropanol it is preferred that ethanol be the major component, ethanol being usually from 60 to 90% of the mixture, preferably about 75% (i.e. in a 3:1 ratio). Of course, other mixtures of the various alkanols may be used, such as ethanol and propylene glycol, and in such mixtures it is also preferred that ethanol be the major component.

The compositions of the present invention contain one or more surface active agents, which may be anionic, nonionic, cationic, ampholytic or zwitterionic detergent compounds. Synthetic organic detergents which may be employed in the practice of the invention may be any of a wide variety of such compounds which are well known and are described at length in the text SuffaceActiveAgents, Vol. II, by Schwartz, Perry and Berch, published in 1958 by Interscience Publishers, the relevant disclosures of which are hereby incorporated by reference.

The nonionic detergents are usually poly-lower alkoxylated lipophiles wherein the desired hydrophile-lipophile balance is obtained from addition of a hydrophilic poly-lower alkoxy group to a lipophilic moiety. For the present compositions the preferred nonionic detergent employed is a polylower alkoxylated higher alkanol wherein the alkanol is of 10 to 1 8 carbon atoms and wherein the number of moles of lower alkylene oxide (of 2 or 3 carbon atoms) is from 3 to 12. Of such materials it is preferred to employ those wherein the higher alkanol is a higher fatty alcohol of 11 or 12 to 1 5 carbon atoms and which contain from 5 to 8 or 5 to 9 lower alkoxy groups per mole. Preferably, the lower alkoxy is ethoxy but in some instances it may be desirably mixed with propoxy, the latter, if present, usually being a minor (less than 50%) constituent.Exemplary of such compounds are those wherein the alkanol is of 12 to 15 carbon atoms and which contain about 7 ethylene oxide groups per mole, e.g. Neodol (Registered Trade Mark) 25-7 and Neodol 23-6.5, which products are made by Shell Chemical Company, Inc. The former is a condensation product of a mixture of higher fatty alcohols averaging about 12 to 1 5 carbon atoms, with about 7 moles of ethylene oxide and the latter is a corresponding mixture wherein the carbon atom content of the higher fatty alcohol is 12 to 13 and the number of ethylene oxide groups per mole averages about 6.5. The higher alcohols are primary alkanols.Other examples of such detergents include Tergitol (Registered Trade Mark) 1 5-S-7 and Tergitol 1 5-S-9, both of which are linear secondary alcohol ethoxylates made by Union Carbide Corporation. The former is a mixed ethoxylation product of an 11 to 1 5 carbon atom linear secondary alkanol with seven moles of ethylene oxide and the latter is a similar product but with nine moles of ethylene oxide being reacted.

Also useful in the present compositions are higher molecular weight nonionics, such as Neodol 45-11, which are similar ethylene oxide condensation products of higher fatty alcohols, with the higher fatty alcohol being of 14 to 1 5 carbon atoms and the number of ethylene oxide groups per mole being about 11. Such products are also made by Shell Chemical Company. Other useful nonionics are represented by Plurafac B-26 (BASF Chemical Company), the reaction product of a higher linear alcohol and a mixture of ethylene and propylene oxides.

In the preferred poly-lower alkoxylated higher alkanols, the best balance of hydrophilic and lipophilic moieties are obtianed when the number of lower alkoxies are from about 40% to 100% of the number of carbon atoms in the higher alcohol, preferably 40 to 60% thereof. The nonionic detergent preferably comprises at least 50% of the preferred ethoxylated alkanols. Higher molecular weight alkanols and various other normally solid nonionic detergent compounds and surfactants may contribute to gelation of the liquid detergent composition and consequently are normally omitted or limited in quantity in the present compositions, although minor proportions thereof may be employed for their cleaning properties, etc.With respect to both preferred and less preferred nonionic detergents, the alkyl groups present therein are preferably linear although a minor degrse of slight branching may be tolerated, such as at a carbon next to or two carbons removed from the terminal carbon of the straight chain and away from the ethoxy chain with the proviso that such branched alkyl is no more than three carbons in length. Normally the proportion of carbon atoms in such a branched configuration will be minor, rarely exceeding 20% of the total carbon atom content of the alkyl. Similarly, although linear alkyls which are terminally joined to the ethylene oxide chains are highly preferred and are considered to result in the optimum combination of detergency, biodegradability and non-gelling characteristics, medial or secondary joinder to the ethylene oxide in the chain may occur.In such instances, it is usually in only a minor proportion of such alkyls, generally less than 20% but as is in the case of the aforementioned Tergitols may be greater. Also, when propylene oxide is present in the lower alkylene oxide chain, it will usually be less than 20% thereof and preferably less than 10% thereof.

With the nonionic detergent, which is the major preferred synthetic organic detergent in the present liquid detergent compositions, there may be employed an anionic detergent. The most preferred anionic detergent compounds are the higher (10 to 18 or 20 carbon atoms) alkyl benzene sulphonate salts wherein the alkyl group preferably contains 10 to 1 5 carbon atoms, most preferably being a straight chain alkyl radical of 1 2 to 13 carbon atoms.Preferably, such an alkyl benzene sulphonate has a high content of 3- (or higher) phenyl isomers and a correspondingly low content (usually well below 50%) of 2- (or lower) phenyl isomers; in other words, the benzene ring is preferably attached in large part at the 3, 4, 5, 6 or 7 position of the alkyl group and the content of isomers in which the benzene ring is attached at the 1 or 2 position is correspondingly low. Typical alkyl benzene sulphonate surface active agents are described in U.S. Patent 3,320,174. Of course, more highly branched alkyl benzene sulphonates may also be employed but usually are not preferred, due to their lack of biodegradability.

Other anionic detergents which are useful are the olefin sulphonate salts. Generally, these contain long chain alkenyl sulphonates or long chain hydroxyalkane sulphonates (with the OH being on the carbon atom which is not directly attached to the carbon atom bearing the -SO3H group). The olefin sulphonate detergent usually comprises a mixture of such types of compounds in varying amounts, often together with long chain disulphonates or sulphate-sulphonates. Such olefin sulphonates are described in many patents, such as U.S.Patent Nos. 2,061,618; 3,409,637; 3,332,880; 3,420,875; 3,428,654; 3,506,580; and British Patent No. 1 ,1 29,158. The number of carbon atoms in the olefin sulphonate is usually within the range of 10 to 25, more commonly 10 to 18 or 20, e.g. a mixture principally of C12/ C14 and C16, having an average of about 14 carbon atoms, or a mixture principally of C14, C16 and Cl8/ having an average of about 16 carbon atoms.

Another class of useful anionic detergents is that of the higher paraffin sulphonates. These may be primary paraffin sulphonates made by reacting long chain alpha-olefins and bisulphites, e.g. sodium bisulphite, or paraffin sulphonates having the sulphonate groups distributed along the paraffin chain, such as the products made by reacting a long chain paraffin with sulphur dioxide and oxygen under ultraviolet light, followed by neutralization with sodium hydroxide or other suitable base (as in U.S.

Patents 2,503,280; 2,507,088; 3,260,741; 3,372,188; and German Patent 735,096). The paraffin sulphonates preferably contain from 1 3 to 17 carbon atoms and will normally be the monosulphonate but if desired, may be di-, tri- or higher sulphonates. Typically, the di- and polysulphonates will be employed in admixture with a corresponding monosulphonate, for example, as a mixture of mono- and disulphonates containing up to about 30% of the disulphonate. The hydrocarbon substituent thereof will preferably be linear but if desired branched chain paraffin sulphonates can be employed, although they are not as good with respect to biodegradability.

Other suitable anionic detergents are sulphated ethoxylated higher fatty alcohols of the formula RO(C2H4O)rnSO3M, wherein R is a fatty alkyl of from 10 to 18 or 20 carbon atoms, m is from 2 to 6 or 8 (preferably having a value from about 1/5 to 1/2 the number of carbon atoms in R) and M is a solubilizing salt-forming cation, such as an alkali metal, ammonium, lower alkylamino or lower alkanolamino, or a higher alkyl benzene sulphonate wherein the higher alkyl is of 10 to 1 5 carbon atoms. As is the case with the preferred nonionic detergent, it will be preferred for the alkyl in the anionic alkoxylate detergent to be a mixture of different chain lengths, such as 11, 1 2, 1 3, 14 and 1 5 carbon atom chains or 12 and 1 3 carbon atom chains, rather than all of one chain length.

Ethylene oxide is the preferred lower aikylene oxide of the anionic alkoxylate detergent, as it is with the nonionic detergent, and the proportion thereof in the polyethoxylated higher alkanol sulphate is preferably 2 to 5 moles of ethylene oxide groups present per mole of anionic detergent, with three moles being most preferred, especially when the higher alkanol is of 11 or 12 to 1 5 carbon atoms.To maintain the desired hydrophile-lipophile balance, when the carbon atom content of the alkyl chain is in the lower portion of the 10 to 1 8 carbon atom range, the ethylene oxide content of the detergent may be reduced to about two moles per mole whereas when the higher alkanol is of 1 6 to 1 8 carbon atoms, in the higher part of the range, the number of ethylene oxide groups may be increased to 4 or 5 and in some cases to as high as 8 or 9. Similarly, the salt-forming cation may be altered to obtain the best solubility. It may be any suitably solubilizing metal or radical but will most frequently be alkali metal, e.g. sodium, or ammonium.If lower alkylamine or alkanolamine groups are utilized the alkyls and alkanols will usually contain from 1 to 4 carbon atoms and the amines and alkanolamines may be mono-, di- and tri-substituted, as in monoethanolamine, diisopropanolamine and trimethylamine.

The poly-lower alkoxy higher alkanol sulphates may be employed in place of or in combination with other preferred anionic detergents such as the higher alkyl benzene sulphonates to supplement the nonionic detergent in the present liquid detergent compositions. A preferred polyethoxylated alcohol sulphate detergent is available from Shell Chemical Company and is marketed as Neodol 253S.

Examples of the higher alcohol polyethenoxy sulphates which may be employed in the liquid detergent compositions of the invention include: mixed C12~l5 normal or primary alkyl triethenoxy sulphate, sodium salt; myristyl triethenoxy sulphate, potassium salt; n-decyl diethenoxy sulphate, diethanolamine salt; lauryl dietheneoxy sulphate, ammonium salt; palmityl tetraethenoxy sulphate, sodium salt; mixed C1415 normal primary alkyl mixed tri- and tetraethenoxy sulphate, sodium salt; stearyl pentaethenoxy sulphate, trimethylamine salt; and mixed C1O18 normal primary alkyl triethenoxy sulphate, potassium salt.

Other useful anionic detergents include the higher acyl sarcosinates, e.g. sodium N-lauroyl sarcosinate; higher fatty alcohol sulphates, such as sodium lauryl sulphate and sodium tallow alcohol sulphate; sulphated oils; sulphates of mono- or di-glycerides of higher fatty acids, e.g. stearic monoglyceride monosulphate; although, of these, the sodium higher alcohol sulphates have been found to be inferior to the polyethoxylated sulphates in detergency; aromatic poly(lower alkenoxy) ether sulphates, such as the sulphates of the condensation products of ethylene oxide and nonyl phenol (usually having 1 to 20 oxyethylene groups per molecule, preferably 2 to 12); polyethoxy higher alcohol sulphates and alkyl phenol polyethoxy sulphates having a lower alkoxy (of 1 to 4 carbon atoms, e.g.

methoxy) substituent on a carbon close to that carrying the sulphate group, such as monomethyl ether monosulphate of a long chain vicinal glycol, e.g. mixture of vicinal alkane diols of 1 6 to 20 carbon atoms in a straight chain; acyl esters of isethionic acid, e.g. oleyl isethionates; acyl N-methyl taurides, e.g. potassium N-methyl lauroyl or oleyl taurides, higher alkyl phenyl polyethoxy sulphonates; higher alkyl phenyl disulphonates, e.g. pentadecyl phenyl disulphonate; and higher fatty acid soaps, e.g. mixed coconut oil and tallow soaps in a 1:4 ratio.

Among the aforementioned types of anionic detergents, the sulphates and sulphonates are generally preferred but the corresponding organic phosphates and phosphonates may also be employed when their contents of phosphorus are not objectionable. Generally, the water soluble anionic synthetic organic detergent, (including soaps), as was previously indicated, are salts of alkali metal cations, such as potassium, lithium, and especially sodium, although salts of ammonium and substituted ammonium cations, such as those previously described, e.g. triethanolamine, triisopropylamine, may be used too. In the above exemplifications of water-soluble anionic detergent it should be considered that the sodium, potassium, ammonium and alkanolamminium salts are individually recited for each detergent.

Ampholytic detergents may be employed in the present compositions, for example in minor proportions in replacement of the anionic detergent or a part thereof or in replacement of part of the nonionic detergent. Ampholytic detergents include the higher fatty carboxylates, phosphates, sulphates or sulphonates which contain a cationic substituent such as an amino group, which may be quaternized, e.g. with a lower alkyl group, or chain extended at the amino group by condensation with a lower alkylene oxide, e.g. ethylene oxide. Generally the compositions containing such ampholytic or cationic detergents will not be as effective and may have a greater tendency to gel or thicken on standing. Therefore they are often avoided.However, if such properties are unobjectionable, minor proportions of ampholytics such as Miranol C2M, sold by Miranol Chemical Company, or Deriphat 151, a sodium N-coco betaamine propionate, sold by General Mills, Inc., may be utilized. A cationic detergent that may sometimes be useful is distearyl dimethyl ammonium chloride (it has fabric softening activity) and the higher fatty amine oxides, such as bis(2-hydroxyethyl) octadecyl amine oxide.

The viscosity control agent preferably utilized to maintain the desired viscosity of the liquid detergent composition, prevent gelation at low temperatures and allow a reduction in lower alkanol solvent content may be a water soluble formate. Sodium formate is preferred but alkali metal formates may be utilized, e.g. potassium formate and various other water soluble formates, including formic acid, which may be added to the liquid detergent composition wherein it dissolves, ionizes and/or reacts to produce essentially the same type of liquid detergent as results from the addition of the alkali metal formate in salt form. Other formates that may be employed are those of water soluble cations, such as previously described as salt-forming cations for the anionic detergents.Although it is preferred to employ the formate viscosity control agent, it has been found that various salts of dibasic acids can also be successfully used, among which the best appears to be disodium adipate, referred to herein as sodium adipate. Other salts of dibasic acids of the formula (CH2)n(COOH)2 where n is 1 to 6 may also be employed and in some instances the salts of monounsaturated acids of the same chain lengths and configurations may be used. However, it is highly preferred to utilize the saturated aliphatic straight chain terminally carboxylated compounds. It is more preferable to employ those wherein n is 3 to 5, most preferably 4, and wherein the acid is fully neutralized, but the acid salts may also be used.

Among the disbasic acids that may be employed, either as the mono- or disalts, are malonic, succinic, glutaric, adipic and pimelic acids. An unsaturated dibasic acid, such as maleic acid, can also be used, at least in part. The acids may be employed without prior neutralization or may be used as their salts, such as disodium malonate, monopotassium succinate, di-triethanolamine glutarate, disodium adipate and monosodium pimelate.

To assist in solubilizing the detergents and optical brighteners which may be present in the liquid detergent compositions, a small proportion of alkaline material or a mixture of such materials is often included in the present formulations. Suitable alkaline materials include mono-, di- and trialkanolamines, alkyl amines, ammonium hydroxides. Of these, the preferred materials are the aikanolamines, preferably the trialkanolamines and of these, especially triethanolamine. The pH of the final liquid detergent composition containing such a basic material will usually be neutral or slightly basic. Satisfactory pH ranges are from 7 to 10, preferably from about 7.5 to 9, and most preferably from about 7.5 to 8.5.

Optical fluorescent brighteners or whiteners preferably employed in the liquid detergent compositions are important constituents of modern detergent compositions which give washed laundry and materials a bright appearance so that the laundry is not only clean but also appears clean.

Although it is possible to utilize a single brightener for a specific intended purpose in the present liquid detergent it is generally desirable to employ mixtures of brighteners which will have good brightening effects on cotton, nylons, polyesters and blends of such materials and which are also bleach stable. A good description of such types of optical brighteners is given in the article "The Requirements of Present Day Detergent Fluorescent Whitening Agents" by A. E. Siegrist, J. Am. Oil Chemists Soc., January 1978 (Vol. 55). That article and U.S. Patent 3,81 2,041, issued 21st May, 1 974, both of which are hereby incorporated by reference for their reievant disclosures, contain detailed descriptions of a wide variety of suitable optical brighteners.

Among the brighteners that are useful in the present liquid detergent compositions are: Calcofluor 5BM (American Cyanamid); Calcofluor White ALF (American Cyanamid); SOF A-2001 (Ciba); CDW (Hilton-Davis); Phorwite RKH, Phorwite BBH and Phorwite SHO (Verona); CSL, powder, acid (American Cyanamid); FB 766 (Verona); Blanchophor PD (GAF); UNPA (Geigy); Tinopal RBS 200 (Geigy). The acid or "nonionic" forms of the brighteners tend to be solubilized by alcohols of the present formulas, while the salts tend to be water soluble.

Adjuvants may be present in the liquid detergent composition to give it additional properties, either functional or aesthetic. Included among the useful adjuvants are soil suspending or antiredeposition agents, such as polyvinyl alcohol, sodium carboxymethyl cellulose, hydroxypropylmethyl cellulose; thickeners, e.g. gums, alginates, agar agar; foam improvers, e.g. lauric myristic diethanolamide; foam destroyers, e.g. silicones; bacteriocides, e.g. tribromosalicylanilide, hexachlorophene; dyes; pigments (water dispersible); preservatives; ultraviolet absorbers; fabric softeners; opacifying agents, e.g. polystyrene suspensions; and perfumes. Of course, such materials will be selected for the properties desired in the finished product and to be compatible with the other constituents thereof.Other adjuvants that may be employed are dihydric or trihydric lower alcohols which, in addition to being solvents and reducing the flash point of the product, can act as anti-freezing constituents and may improve compatibilities of the solvent system with particular product components. Among these compounds the most preferred group includes the lower polyols of 2 to 3 carbon atoms, e.g. ethylene glycol, propylene glycol and glycerol, but the lower alkyl (C1C4) etheric derivatives of such compounds, known as Cellosolves (Registered Trade Mark), may also be employed.

The proportions of such substitutes for the lower alkanols will be limited, normally being held to no more than 20% of the total alcohol content of the liquid detergent.

Another category of useful additives are hydrotropes which serve to enhance the solubility in aqueous solution of components which otherwise have limited solubility in water. Useful hydrotropes includes the alkali metal, ammonium and ethanolamine salts of the following acids: (1) aryl sulphonic acids, such as benzene sulphonic acid and C1-C3 alkyl-substituted benzene sulphonic acids, e.g.

toluene sulphonic acid and xylene sulphonic acid; and (2) C5Ce alkyl sulphuric acids, such as hexyl sulphuric acid.

The proportions of the various components of the present liquid detergent compositions are important for the manufacture of a uniform product of desirable viscosity and acceptable heavy duty laundering action which does not gel at low temperatures or upon standing in an open container at room temperature.

To promote solubility of the fluorescent brighteners and other constituents in the detergent composition and to make a clear, homogeneous and readily pourable liquid product, from 10 to 60% of the total liquid detergent concentrate should be nonionic detergent. Preferably, especially when an anionic detergent is present in the liquid product, the proportion of the nonionic detergent is from 20 to 40% and more preferably it is 30 to 40%, with the best formula known at the present time including about 32%. The proportion of anionic detergent will usually be in the range of 3 to 15%, preferably 4 to 12% and most preferably 6 to 10% with the best formula known at the present including about 7% thereof.The ratio of total nonionic detergent to anionic detergent will normally be from 15:1 to 1 :1, with 8:1 to 2:1 being preferred and 5:1 to 3:1 being most preferred.

When present, the lower alkanol in the liquid detergent compositions will generally be present in a sufficient proportion to aid in dissolving and/or stabilizing the various constituents in the final product. The proportions of lower alkanol used will normally be from about 3 to 15%, preferably 4 to 12%, more preferably 4 to 8% and at the present time most preferably about 5%.' Viscosity control agents which may be used or a mixture of such agents will normally be from about 0.5% to 5% of the final liquid detergent composition, preferably about 0.5 to 3%, and most preferably about 1%.

The percentage of water, generally the main solvent in the present compositions, will usually be from about 25 to 85%, preferably 35 to 65% and most preferably from about 40 to 55%, by weight, of the liquid composition. In the most preferred formulations there will be about 45 to 50% water.

The content of the alkaline additive, such as triethanolamine, when provided in the liquid composition is usually from about 0.1 to 5% of the composition and preferably 1 to 3%, by weight, thereof. The total proportion of optical brightener is normally from about 0.05 to 1.5%, preferably about 0.1 to 1% and most preferably about 0.2 to 0.5%.

The liquid detergent compositions of the present invention, can be made by simple manufacturing techniques. In a typical manufacturing method the optical brighteners are slurried in the monohydric alcohol, after which water is added to the slurry together with a small amount of a base, such as triethanolamine, which helps partially to dissolve the previously suspended material. Addition of the anionic detergent compound usually results in the remainder of the brightener dissolving to make a clear solution. The viscosity control agent is then added as the acid, acidic salt or completely neutralized salt, preferably the sodium or potassium salt, and agitation is continued until the solution becomes clarified, which may normally take about 5 to 10 minutes.At this point the principal detergent, the nonionic, is added along with a minor amount of acid for purposes of pH regulation, the pH being generally adjusted to a value at which the proteolytic enzyme used is most stable. This is followed by agitation of the solution and the addition of adjuvants, such as, perfume and dye which give the product its final desired properties. The protease and a-amylase enzyme preparations are then added to the solution and mixed therewith as the final step in producing the product liquid detergent composition. If desired the viscosity control additive may be incorporated earlier in the procedure.

The above operations may be effected at room temperature, although suitable temperatures within the range of 20C to 500C may be employed, as desired, with the proviso that when volatile materials, such as perfume, are added, the temperature should be low enough so as to avoid objectionable losses. The product obtained will usually have a pH within the range of 7 to 10, and a density within the range of from 0.9 to 1.1, preferably from 0.95 to 1.05. The viscosity of the final product at 24"C will be in the range of 60 to 1 50 centipoises, preferably from about 80 to 140 centipoises, and most preferably from about 11 5 to 135 centipoises, according to measurements that are made with a Brookfied viscosimeter at room temperature.

The present liquid compositions are efficient and easy to use. Compare to heavy duty laundry detergent powders, much smaller volumes of the present liquids are employed to obtain comparable cleaning of soiled laundry. For example, using a typical preferred formulation of this invention, only about 60 grams or 1/4 cup of liquid is needed for a full tub of wash in a top-loading automatic washing machine in which the water volume is 15 to 18 U.S. gallons (55 to 75 litres); and even less (about 1/2) is needed for front-loading machines.Thus, the concentration of the liquid detergent composition in the wash water is in the order of about 0.1%. Usually, the proportion of the liquid composition in the wash solution will range from about 0.05 to 0.3%, preferably from 0.08 to 0.2% and most preferably from about 0.1 to 0.1 5%. The proportions of the various constituents of the liquid composition may vary accordingly. Equivalent results can be obtained by using greater proportions of a more dilute formulation but the greater quantity needed will require additional packaging and will generally be less convenient for consumer use. Also, more highly diluted products will be more apt to freeze in cold weather, and may be more subject to hydrolysis and chemical changes on storage.

The following examples are given to illustrate the invention.

Example 1 A liquid detergent composition (containing no enzymes) designed as composition "A" was prepared at room temperature by mixing the following components in the stated proportions: Component Weight percent Ethoxylated C12-C15 primary alcohol 32.0 (7 Moles EO/mole alcohol) Sodium dodecyl benzene sulphonate 7.0 Triethanolamine 2.8 Ethanol 5.0 Sodium formate 1.0 H2SO4 (conc.) 0.7 Optical brighteners)l) 0.27 Dye(2) 0.01 Perfume 0.35 Water balance (1) A mixture of Phorwite RKH and Phorwite BHC brighteners manufactured by Verona.

(2) Polar Brilliant Blue (PBB) manufactured by Ciba-Geigy.

Enzyme-containing liquid detergent compositions B-U were formulated by adding various amounts of protease and alpha-amylase enzymes to the above-described composition A. The enzyme concentration in each of the detergent compositions is shown in Table 1, expressed in terms of percent of enzyme formulation based on the weight of the composition. The protease enzyme employed was a liquid enzyme formulation sold under the name "Alcalase" by Novo Industries of Copenhagen, Denmark having a concentration of 2.5 Anson Units per gram of enzyme preparation. The alphaamylase enzyme employed was a liquid enzyme formulation sold under the name "Termamyl" by Novo Industries having a concentration of 120,000 Novo amylase units per gram of liquid enzyme preparation.

Test procedure A total of 6 cotton swatches, 3 stained with beef liver blood and 3 stained with grass, were placed in each of 4 buckets of a Tergotometer vessel manufactured by U.S. Testing Company. A series of laundering tests were conducted using a different liquid detergent composition from compositions A-U in each bucket of the Tergotometer under the following test conditions: Liquid detergent concentration 0.09% Agitation 100 rpm Agitation time 10 minutes Water temperature 120 F Water hardness About 1 50 ppm as calcium carbonate At the end of the wash, the test swatches were rinsed in tap water and then dried. The percent stain removal was measured by taking a reflectance reading for each stained test swatch prior to and after the washing using a Gardner XL-20 Colorimeter, and the percent stain removal (% S.R.) was calculated as follows: (Rd after washing)-(Rd before washing) % S.R.= (Rd before staining)-(Rd before washing) wherein "Rd before washing" represents the Rd value after staining.

The values of percent stain removal calculated for each of the three test swatches having a common stain were averaged for each liquid detergent composition tested. The results are shown in Table 1 which sets forth the percentage S.R. for each of the liquid detergent compositions tested (compositions A-U) and the enzyme concentration of such detergent compositions.

Table 1 Comparative stain removal with enzyme-containing detergent compositions % Stain removal Beef Weight % Weight % liver Composition protease (1) a-amylase(2) blood Grass A 0.0 0.0 42.0 31.5 B 0.2 0.0 50.8 37.6 C 0.4 0.0 52.8 36.7 D 0.6 0.0 53.9 36.8 E 0.8 0.0 55.5 36.1 F 0.0 0.2 44.2 37.6 G 0.2 0.2 55.3 42.4 H 0.4 0.2 58.4 44.8 I 0.6 0.2 60.6 44.5 J 0.8 0.2 60.5 44.1 K 0.0 0.4 47.1 38.3 L 0.2 0.4 56.2 43.4 M 0.4 0.4 58.6 45.0 N 0.6 0.4 63.3 44.8 0 0.8 0.4 63.2 45.0 P 0.0 0.6 47.7 37.6 Q 0.2 0.6 55.4 41.3 R 0.4 0.6 57.5 42.1 S 0.6 0.6 60.9 43.7 T 0.8 0.6 62.0 44.5 U 0.0 0.8 47.7 36.5 the proteolytic activity of Alcalase is 2.5 Anson units per gram.Thus, a concentration of, for exmaple,0.2% of Alcalase in the liquid detergent composition corresponds to a protease enzyme activity of 0.5 Anson units (0.2x2.5) per 100 grams of detergent composition.

12)The amylolytic activity of Termamyl is 1 20,000 Novo amylase units per gram. Thus, a concentration of 0.2% Termamyl in the liquid detergent composition corresponds to an a-amylase emzyme activity of 24,000 Novo amylase units (0.2x 120,000) per 100 grams of detergent composition.

As indicated in Table 1 , the percentage stain removal (S.R.) achieved with composition A represents the S.R. achieved in the absence of enzymes in the detergent composition. Referring to the S.R. data for the beef liver blood stain, a comparison of the S.R. achieved with compositions F, K, P and U, all of which contain amylase enzyme, but no protease and are therefore not in accordance with the invention, shows that composition P containing 0.6 wt.% a-amylase provided the maximum improvement in S.R. (47.7%) achievable with amylase enzyme, i.e. an increase of about 5.7 percentage points relative to the S.R. value of 42.0% for the enzyme-free composition A. Similarity, a comparison of the S.R. achieved with compositions B, C, D and E, all of which contain protease enzyme, but no amylase, shows that composition E containing 0.8% protease provided the maximum improvement in S.R. (55.5%) with protease enzyme, i.e. an increase of about 1 3.5 percentage points relative to the 42% S.R. achieved with enzyme-free composition A.

The synergistic interaction of protease and amylase enzymes for the removal of proteinaceous stains is evident from Table 1. Thus, for example, composition G containing 0.2 wt% protease and 0.2 wt% amylase enzymes (corresponding to an amylase-protease enzyme activity ratio of 24,000 Novo amylase units per 0.5 Anson units) provided nearly the same improvement in S.R. (relative to enzymefree composition A) as was achieved with 0.8 wt% protease in composition E. From an economic standpoint, the use of composition G containing a mixture of enzymes in accordance with the invention clearly represents a substantial reduction in the reequirement for the relatively expensive protease enzyme, as compared to composition E.

The highest percentage of stain removal was achieved with composition N. Specifically, the combination of 0.6 wt% protease and 0.4 wt% amylase in composition N provided a greater than 21% increase in the percent S.R. for, the blood stain relative to enzyme-free composition A. Thus, the 63.3% S.R. achieved with composition N is significantly higher than the maximum S.R. that should be achieved with detergent compositions containing protease enzyme in the absence of a-amylase. The amylase-protease enzyme activity ratio of such composition N is 48,000 Novo amylase units per 1.5 Anson units.

The synergistic interaction of protease and alpha-amylase enzymes is likewise evident in the S.R.

data for the grass stain. Thus, for example, composition H containing 0.2% amylase and 0.4% protease enzymes provided a substantially higher S.R. than could be achieved with detergent compositions containing either protease or amylase as individual enzymes in the composition.

Claims (27)

Claims

1. A liquid detergent composition comprising a detergent and an enzyme mixture comprising an alkaline protease enzyme and an a-amylase enzyme in relative proportions such that the ratio of the respective enzyme activities in the mixture is from about 4,000 to about 80,000 Novo amylase units of a-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 100 grams of detergent composition.

2. A detergent composition as claimed in Claim 1, including one or more anionic, nonionic, cationic, ampholytic and/or zwitterionic detergent compounds.

3. A detergent composition as claimed in Claim 1 or 2, wherein the detergent is present from 5% to 75% by weight.

4. A detergent composition as claimed in Claim 1,2 or 3, including from 25% to 85% water.

5. A detergent composition as claimed in any one of Claims 1 to 4 wherein the ratio of the enzyme activities in the enzyme mixture is from about 1 5,000 to about 40,000 Novo amylase units of a-amylase per Anson unit of protease, and the protease is present in an amount to provide from about 0.5 to about 2.0 Anson units per 100 grams of detergent composition.

6. A detergent composition as claimed in any one of Claims 1 to 5 wherein the ratio of enzyme activities is from about 30,000 to about 40,000 Novo amylase units of a-amylase per Anson unit of protease.

7. A detergent composition as claimed in any one of Claims 1 to 6 inlcuding from 20 to 40% by weight of a mixture of a nonionic detergent compound.

8. A detergent composition as claimed in Claim 7, wherein the nonionic detergent compound is a water-soluble C2-C3 alkoxylated C10-C18 alkanol.

9. A detergent composition as claimed in any one of Claims 1 to 8 including from 4 to 12% by weight of an anionic detergent compound.

1 0. A detergent composition as claimed in Claim 9, wherein the anionic detergent compound is a water soluble salt of a C10-C16 alkyl benzene sulphonate.

11. A detergent composition as claimed in any one of Claims 1 to 10 which contains, in addition, from 3 to 15%, by weight, of a lower alkanol.

12. A detergent composition as claimed in Claim 11, wherein the lower alkanol comprises a lower monoalcohol having 1 to 4 carbon atoms and/or a lower polyol having 2 to 3 carbon atoms.

1 3. A detergent composition as claimed in any one of Claims 1 to 9 which contains, in addition, from about 0.5 to 5%, by weight, of a viscosity control agent.

1 4. A detergent composition as claimed in Claim 13, wherein the viscosity control agent comprises a water-soluble formate salt and/or dibasic acid of the formula (CH2)n(COOH)2 wherein n is 1 to 6.

1 5. A detergent composition as claimed in any one of Claims 1 to 14 which, in addition, contains from 0.1 to 5%, by weight, of an alkanolamine.

1 6. A detergent composition as claimed in any one of Claims 1 to 1 5 wherein the ratio of enzyme is from about 30,000 to about 40,000 Novo amylase units of a-amylase per Anson unit of protease.

1 7. A detergent composition as claimed in Claim 7 wherein the nonionic detergent compound is a polyethoxylated C12-C15 alkanol having from 3 to 12 ethylene oxide groups per mole.

1 8. A detergent composition as claimed in Claim 9, wherein the anionic detergent is a C12-C13 alkyl benzene sulphonate.

19. A detergent composition as claimed in Claim 11, wherein the lower alkanol is ethanol or a mixture of ethanol and isopropanol.

20. A detergent composition as claimed in Claim 13, wherein the viscosity control agent is sodium formate.

21. A method of laundering comprising contacting stained and/or soiled fabrics to be laundered with a liquid detergent composition as claimed in any one of Claims 1 to 20.

22. A liquid detergent composition as claimed in Claim 1 substantially as described with reference to any one of the Examples.

23. A method of laundering as claimed in Claim 21 substantially as described with reference to any one of the examples.

24. An enzyme-containing liquid detergent composition comprising: (a) from 5 to 75%, by weight, of one or more detergent surface active agents selected from nonionic, cationic, ampholytic and zwitterionic detergent compounds; (b) from 25 to 85% water; and (c) an enzyme mixture consisting essentially of an alkaline protease enzyme and an a-amylase enzyme in relative proportions such that the ratio of the respective enzyme activities in the mixture is from about 4,000 to about 80,000 Novo amylase units of a-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 100 grams of detergent composition.

25. An enzyme-containing liquid detergent composition consisting essentially of (a) from 20 to 40%, by weight, of a nonionic detergent compound consisting essentially of a water-soluble C2-C3 alkoxylated C,OC18 alkanol; (b) from 4 to 12%, by weight, of an anionic detergent compound consisting essentially of a water soluble salt of a C10-C15 alkyl benzene sulphonate; (c) from 3 to 1 5%, by weight, of a lower alkanol selected from lower mono-alcohols having 1 to 4 carbon atoms, a lower polyol having 2 to 3 carbon atoms and mixtures thereof; (d) from 0.5 to 5%, by weight, of a viscosity control agent consisting essentially of a water soluble formate salt; (e) from 35 to 65%, by weight, water; and (f) an enzyme mixture consisting essentially of an alkaline protease enzyme and an a-amylase enzyme in relative proportions such that the ratio of the respective enzyme activities in the mixture is from about 4,000 to about 80,000 Novo amylase units of a-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 1 00 grams of detergent composition.

26. A method of laundering comprising contacting stained and/or soiled fabrics to be laundered with an enzyme-containing liquid detergent composition comprising: (a) from 5 to 75%, by weight, of one or more detergent surface active agents selected from anionic, nonionic, cationic, ampholytic and zwitterionic detergent compounds; (b) from 25 to 85% water; and (c) an enzyme mixture consisting essentially of an alkaline protease enzyme and an a-amylase enzyme in relative proportions such that the ratio of the respective enzyme activities in the mixture is from about 4,000 to about 80,000 Novo amylase units of a-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 100 grams of detergent composition.

27. A method as claimed in Claim 26 wherein the liquid detergent composition consists essentially of (a) from 20 to 40%, by weight, of a nonionic detergent compound consisting essentially of a water-soluble C2-C3 alkoxylated C10-C18 alkanol; (b) from 4 to 12%, by weight, of an anionic detergent compound consisting essentially of a water soluble salt of a C10-C16 alkyl benzene sulphonate; (c) from 3 to 1 5%, by weight, of a lower alkanol selected from the group consisting of a lower mono-alcohol having 1 to 4 carbon atoms, a lower polyol having 2 to 3 carbon atoms and mixtures thereof; (d) from 0.5 to 5%, by weight, of a viscosity control agent consisting essentially of a water soluble formate salt; (e) from 35 to 65%, by weight, water; and (f) an enzyme mixture consisting essentially of an alkaline protease enzyme and an a-amylase enzyme in relative proportions such that the ratio of the respective enzyme activities in the mixture is from about 4,000 to about 80,000 Novo amylase units of a-amylase per Anson unit of protease, the protease being present in an amount to provide from about 0.25 to about 2.5 Anson units per 100 grams of detergent composition.