GB2372261A - Bleaching composition - Google Patents

Abstract

A bleaching composition is provided comprising <SL> <LI>a) a bleach-effective amount of an oxidoreductase; <LI>b) 0 to 10 wt% of a surfactant; <LI>c) less than 20 wt% of a modifier; and <LI>d) an effective dry cleaning amount of densified carbon dioxide. </SL> It is particularly useful for removing stains from textiles.

Description

Bleaching composition

Field of the invention The present invention relates to the field of bleaching compositions to remove stains from articles, in particular textile articles. In addition the present invention relates to a method of preparing a bleaching composition and method to bleach articles.

Background of the invention It is known in the art to use hydrogen peroxide or organic peracids or their precursors to remove stains from metal, ceramic, plastic or textile articles. Notorious are tea stains or oily tomato stains from for example tomato sauces.

More recently, cleaning with carbon dioxide has been described. Dense phase carbon dioxide has been suggested as an alternative to perchloroethylene for health and environmental reasons. For example, a dry cleaning system in which chilled liquid carbon dioxide is used to extract soils from fabrics is described in US-A-4 012 194.

However, it has been recognised that additives are needed to boost the cleaning by this medium. For example, the use of ethoxylated tertiary acetylenic alcohol and diol surfactants for boosting the cleaning performance from condensed phase carbon dioxide are taught in US-A-5 789 505. US-A-5 431 843 discloses a perhydrolysis system for use in condensed fluid medium for bleaching of stained garments. This perhydrolysis system comprises two essential components: hydrogen peroxide and an organic peracid precursor. The peracid may be the product of an enzymatic hydrolysis of a substrate and a source of peroxide. The

enzymes should be esterase, lipase or protease. However, using peracids has many drawbacks. Although a better overall stain removal with the bleaching system of US-A-5 431 843 is possible when compared to hydrogen peroxide alone, to obtain these results, the bleaching process takes place for at least 1 hour. US-A-5 676 705 describes the use of organic peracid precursor in a dry cleaning process using carbon dioxide. Herein, both the preformed peracids and the directly added organic peracid precursor should be soluble in densified carbon dioxide.

Although organic peracids and/or precursor systems are generally effective they still exhibit several disadvantages. For example, these precursor systems have large formulation space requirements as they also need addition of hydrogen peroxide and/or a hydrogen peroxide delivery system. Consequently, a significant proportion of the cleaning formulation must be devoted to the bleach components, leaving less room for other active ingredients and complicating the development of concentrated formulations. Moreover, organic precursor systems do not bleach very efficiently in situations wherein short bleach times are desired and processing environment is acidic or pH neutral.

Accordingly, it is an object of the invention to provide an alternative bleaching composition and method of bleaching which shows effective stain removal but does not display one or more of these drawbacks. One particular object of the invention is to provide a bleaching composition and method of bleaching which are economical and require short bleach times. Another object of the invention is to provide

a bleaching composition and a method of bleaching which are particularly suitable for removing, tea and oily tomato stains.

Surprisingly, we have now found that one or more of these objects can be achieved by the inventive bleaching composition and method of bleaching.

Definition of the invention Accordingly, in a first aspect of the invention a bleaching composition is provided comprising a) a bleach-effective amount of an oxidoreductase ; b) 0 to 10 wt% of a surfactant; c) less than 20 wt% of a modifier; and d) an effective dry cleaning amount of densified carbon dioxide.

In a second aspect of the invention a bleaching method is provided comprising the step of contacting an article with a bleaching composition according to the invention.

Preferably, the inventive composition and method is suitable to bleach articles in less than 45 min.

Detailed description of the invention The present invention is particularly advantageous for bleaching methods that require a short period of time. US A-5 431 843 describes bleaching times of 1 hour for effective stain removal. Unexpectedly we have now found that the present invention provides effective bleaching in 45 minutes or less. Another advantage of the present invention is the simplicity. Organic peracid precursors as

described in the prior art often need a high pH to drive the perhydrolysis process. Since carbon dioxide has a low pH, special measures have to be taken to ensure the formation of relatively unstable peracids in a separate premix process. Furthermore, the low temperatures used in carbon dioxide cleaning will also slow this reaction. It is believed that the oxidoreductases are able to rapidly and effectively remove stains because these oxidoreductases do not need to be formed from a precursor such as is the case with organic peroxyacid precursor and hydrogen peroxide. Consequently, another advantage of the present invention is that it is remarkably effective on a variety of stains, especially tea and oily tomato stains. Without wishing to be bound by theory it is believed that because the inventive oxidoreductase s are insoluble in carbon dioxide, only minute amounts will be present in the carbon dioxide phase resulting in less dye damage.

The present invention is especially suitable to bleach and clean garments but may also be employed to bleach articles with hard surfaces.

For purposes of the invention, the following definitions are used: "The bleaching composition" describes the total of the densified carbon dioxide, the oxidoreductase, the modifier if present and optionally other additives.

"Additives"are compounds to enhance the cleaning effect of the bleaching composition such as surfactants, whiteners, softeners, enzymes, perfume and antistat.

"Liquid carbon dioxide"means carbon dioxide which has a temperature of about 30 C or less.

"Supercritical fluid carbon dioxide"means carbon dioxide which is at or above the critical temperature of 31 C and the critical pressure of 7.2 Mpa (71 atmospheres) and which cannot be condensed into a liquid phase despite the addition of further pressure.

The term"densified carbon dioxide"encompasses both liquid and supercritical fluid carbon dioxide.

The bleaching composition is defined as the composition wherein the actual bleaching occurs analogous to a wash liquor. In practice this bleaching composition may be prepared by adding a bleaching product to the carbon dioxide analogous to adding a detergent product to the wash liquor.

Oxidoreductase To the class of oxidoreductases belong all enzymes catalysing oxidoreduction reactions. The substrate that is oxidised is regarded as hydrogen donor. The systematic name is based on donor: acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever is possible; as an alternative, reductase can be used. Oxidase is only used in cases where 02 is the acceptor.

Examples of preferred oxidoreductases are oxidases such as glucose oxidase, methanol oxidase, bilirubin oxidase, catechol oxidase, laccase, peroxidases such as ligninase and those described in WO-A-97/31090, monooxygenase, dioxygenase such as lipoxygenase and other oxygenases as described in WO-A-99/02632, WO-A-99/02638, WO-A-99/02639 and the cytochrome based enzymatic bleaching systems described in WO-A-99/02641.

Peroxidases are used in combination with hydrogen peroxide, which can be formulated into a detergent composition as percarbonate or perborate. The hydrogen peroxide may also be generated during the cleaning and/or rinsing process by an enzymatic system as e. g. described in EP-A-537381.

The activity of oxidoreductases, in particular the phenol oxidising enzymes in a process for bleaching stains on fabrics and/or dyes in solution and/or antimicrobial treatment can be enhanced by adding certain organic compounds, called enhancers. Examples of enhancers are 2, 2'-azo-bis- (3-ethylbenzo-thiazoline-6-sulphonate (ABTS) and Phenothiazine-10-propionate (PTP). More enhancers are described in WO-A-94/12619, WO-A-94/12620, WO-A-94/12621, WO-A-97/11217, WO-A-99/23887. Accromonium Murorum Oxidase is example of a phenol oxidase from the subclass of laccases.

Phenol oxidases and peroxidases are preferably used together with a enhancer. The level of enhancer is preferably from 0 to 5000 microM, more preferably from 1 to 2000 microM, more preferably, from 5 to 1000 microM most preferably 10 to 800 microM (per L carbon dioxide).

If hydrogen peroxide is used, e. g. with peroxidases, it is

preferably used from 0 to 400 mM, more preferably from 0. 01 to 200 mM, more preferably from 0. 05 to 150 mM, most preferably from 0.1 to 100 mM (per L carbon dioxide).

Preferably, the oxidoreductase according to the invention is selected from oxygen oxidoreductases, hydrogen-peroxide oxidoreductases and mixtures thereof.

Preferred examples of oxygen oxidoreductases are lipoxigenase [EC classification 1. 13. 11. 12], glucose oxidase [EC classification 1.1. 3. 4], maltose oxidase [EC classification 1.1. 3. 5] and Accromonium Murorum Oxidase (AMO) [EC classification 1.10. 3. 2]. Examples of hydrogenperoxide oxidoreductases are Arthromyces Ramosus Peroxidase ; a hemoprotein (ARP) [EC classification

1. 11. 1. 7] and Chloride peroxidase (CPO) [EC classification 1. 11. 1. 10].

The oxidoreductases can be described by the reaction they catalyse. For example lipoxigenase (Lipoxidase or carotene oxidase, systematic name: Linoleate: oxygen 13-oxidoreductase)

catalyses the following reaction Linoleate + Oz < - (9Z, 11E)- (13S)-13hydroperoxyoctadeca-9, 11-dienoate Glucose oxidase (Glucose oxyhydrase, systematic name : -D-Glucose : oxygen l-oxidoreductase) catalyses the reaction -D-Glucose + 02 #D-Glucono-1, 5-lactone + H2O2 Maltose oxidase (hexose oxidase, systematic name: D-Hexose: oxygen l-oxidoreductase) catalyses the reaction

P-D-Glucose + 02 < -D-Glucono-l, 5-lactone + H202 The hemoprotein ARP (systematic name : Donor : hydrogen peroxide oxidoreductase) catalyses the reaction Donor + H202 = oxidised donor + 2H20 The laccase AMO (systematic name: Benzenediol: oxygen oxidoreductase) catalyses the reaction 4 Benzenediol + 02 = 4 benzosemiquinone + 2H20 The peroxidase CPO (systematic name: Chloride: Hydrogenperoxide oxidoreductase) catalyses the reaction 2RH + 2Cl- + H2O2 2 RC1 + 2H20 The inventive composition comprises a bleach-effective amount of oxidoreductase. The exact amount will depend on the volume of carbon dioxide, number of articles and nature and quantity of stains. The skilled person will be able to determine the bleach-effective amount without undue burden.

Preferably, the oxidoreductase is present in the bleaching composition from 1. 0*10-4 mg/L to 1. 0*103 mg/L, more preferably, from 1. 0*10-3 mg/L to 5. 0*102 mg/L and even more preferably from 1. 0*10-2 mg/L to 2. 0*102 mg/L carbon dioxide.

Surfactants Preferably, the bleach composition according the invention comprises a surfactant. Any surfactant known to the person skilled in the art may be used. Surfactants are described

in US-A-5, 789, 505, US-A-5, 683, 977, US-A-5, 683, 473, US-A5, 858, 022 and WO 96/27704. Especially preferred are the surfactants described in WO 96/27704 (formula's I-IV).

With regard to the surfactants the following definitions will be used for the present invention. The term"densified carbon dioxide-philic"in reference to surfactants RnZm wherein n and m are each independently 1 to 50, means that the functional group, Rn-is soluble in carbon dioxide at pressures of from 101 kPa to 68.9 MPa and temperatures of from-78. 5 to 100oC to greater than 10 weight percent.

Preferably n and m are each independently 1-35. Such functional groups (Rn-) include halocarbons, polysiloxanes and branched polyalkylene oxides.

The term"densified carbon dioxide-phobic"in reference to surfactants, RnZm, means that Zm-will have a solubility in carbon dioxide of less than 10 weight percent at pressures

of from 101 kPa to 68. 9 MPa and temperatures of from-78. 5 to 100oC. The functional groups in Zm-include carboxylic acids, phosphatyl esters, hydroxyls, Cl-30 alkyls or alkenyls, polyalkylene oxides, branched polyalkylene oxides, carboxylates, Cl-30 alkyl sulphonates, phosphates, glycerates, carbohydrates, nitrates, substituted or unsubstituted aryls and sulphates.

The hydrocarbon and halocarbon containing surfactants (i. e., RnZm, containing the CO2-philic functional group, Rn , and the CO2-phobic group, Zm-) may have an HLB of less than 15, preferably less than 13 and most preferably less than 12.

The polymeric siloxane containing surfactants, R, Zm, also designated MDxD*yM, with M representing trimethylsiloxyl end groups, Dx as a dimethylsiloxyl backbone (CO2-philic functional group) and D*y as one or more substituted methylsiloxyl groups substituted with CO2-phobic R or R' groups preferably have a DxD*y ratio of greater than 0.5 : 1, preferably greater than 0.7 : 1 and most preferably greater than 1: 1.

A"substituted methylsiloxyl group"is a methylsiloxyl group substituted with a CO2-phobic group R or R'. R or R' are each represented in the following formula: - (CH2) a (C6H4) b (A) d- [ (L) e (A')f]n- (L') gZ (G) h wherein a is 1-30, b is 0-1, C6H4 is substituted or unsubstituted with a Cl-lo alkyl or alkenyl and A, d, L, e, A', F, n L', g, Z, G and h are defined below, and mixtures of R and R'.

A"substituted aryl"is an aryl substituted with a Cl-30 alkyl, alkenyl or hydroxyl, preferably a Cl-20 alkyl or alkenyl.

A"substituted carbohydrate"is a carbohydrate substituted with a C1-10 alkyl or alkenyl, preferably a Cl-5 alkyl.

The terms"polyalkylene oxide","alkyl"and"alkenyl"each contain a carbon chain which may be either straight or branched unless otherwise stated.

A preferred surfactant which is effective for use in a carbon dioxide bleach composition requires the combination

of densified carbon dioxide-philic functional groups with densified carbon dioxide-phobic functional groups (see definitions above). The resulting compound may form reversed micelles with the CO2-philic functional groups extending into a continuous phase and the CO2-phobic functional groups directed toward the centre of the micelle.

The surfactant is preferably present in an amount of less than 10 wt% or more preferably of from 0.001 to 10 wt%, preferably 0.01 to 5 wt%. An especially preferred range is from about 0.03% to about 1 wt%.

If present, the CO2-philic moieties of the surfactants are preferably groups exhibiting low Hildebrand solubility parameters, as described in Grant, D. J. W. et al.

"Solubility Behavior of Organic Compounds", Techniques of Chemistry Series, J. Wiley & Sons, NY (1990) pp. 46-55 which describes the Hildebrand solubility equation, herein incorporated by reference. These CO2-philic moieties also exhibit low polarisability and some electron donating capability allowing them to be solubilised easily in densified fluid carbon dioxide.

As defined above the CO2-philic functional groups are soluble in densified carbon dioxide to greater than 10 weight percent, preferably greater than 15 weight percent, at pressures of from 101 kPa to 68.9 MPa and temperatures of from-78. 5 to 100oC.

Preferred densified CO2-philic functional groups include halocarbons (such as fluoro-, chloro-and fluoro

chlorocarbons), polysiloxanes and branched polyalkylene oxides.

The CO2-phobic portion of the surfactant molecule is obtained either by a hydrophilic or a hydrophobic functional group which is less than 10 weight percent soluble in densified CO2, preferably less than 5 wt. %, at a pressures of from 101 kPa to 68.9 MPa and temperatures of

from-78. 5 to 100oC. Examples of moieties contained in the CO2-phobic groups include polyalkylene oxides, carboxylates, branched acrylate esters, Cl-30 hydrocarbons, aryls which are unsubstituted or substituted, sulphonates, glycerates, phosphates, sulphates and carbohydrates.

Especially preferred CO2-phobic groups include C2-20 straight chain or branched alkyls, polyalkylene oxides, glycerates, carboxylates, phosphates, sulphates and carbohydrates.

Preferred surfactants comprise CO2-philic and CO2-phobic groups. The CO2-philic and CO2-phobic groups are preferably directly connected or linked together via a linkage group.

Such groups preferably include ester, keto, ether, amide, amine, thio, alkyl, alkenyl, fluoroalkyl, fluoroalkenyl and mixtures thereof.

A preferred surfactant is: R, Z, wherein Rn-is a densified CO2-philic functional group, R is a halocarbon, a polysiloxane, or a

branched polyalkylene oxide and n is 1-50, and Zmis a densified CO2-phobic functional group, and

m is 1-50 and at pressures of 101 kPa to 68. 9 MPa and temperatures of from-78. 5 to 1000C, the Rn-group is soluble in the densified carbon dioxide to greater than 10 wt. percent and the Zm-group is soluble in the densified carbon dioxide to less than 10 wt. percent. It should be understood that Rn-and Zm-may be present in any sequence, e. g. RZR, ZRZ, RRRZ, RRRZRZ etc. etc.

Preferably, when R of the surfactant is the halocarbon or the branched polyalkylene oxide, then the surfactant has an HLB value of less than 15. In other cases it may be preferred that when R is the polysiloxane, then the surfactant has a ratio of dimethyl siloxyl to substituted methyl siloxy groups of greater than 0.5 : 1.

Surfactants which are useful in the invention may be selected from four groups of compounds (formula I-IV). The first group of compounds has the following formula: [ (CX3 (CX2) a (CH2 h) c (A) d- [ (L) e-- (A') f] n-- (L') g] oZ (G h (I) wherein X is F, Cl, Br, I and mixtures thereof, preferably F and Cl ; a is 1-30, preferably 1-25, most preferably 5-20; b is 0-5, preferably 0-3 ; c is 1-5, preferably 1-3 ; A and A'are each independently a linking moiety representing an ester, a keto, an ether, a thio, an amido, an amino, a Cl-4 fluoralkyl, a Cl-4 fluoroalkenyl, a branched or straight chain polyalkylene oxide, a phosphato, a sulphonyl, a sulphate, an ammonium and mixtures thereof ; d is 0 or 1 ;

L and L'are each independently a Cl-30 straight chained or branched alkyl or alkenyl or an aryl which is unsubstituted or substituted and mixtures thereof ; e is 0-3; f is 0 or 1; n is 0-10, preferably 0-5, most preferably 0-3; g is 0-3; o is 0-5, preferably 0-3 ; Z is a hydrogen, a carboxylic acid, a hydroxy, a phosphato, a phosphato ester, a sulphonyl, a sulphonate, a sulphate, a branched or straight-chained polyalkylene oxide, a nitryl, a glyceryl, an aryl unsubstituted or substituted with a Ci-go alkyl or alkenyl, (preferably Cl-25 alkyl), a carbohydrate unsubstituted or substituted with a C1-10 alkyl or alkenyl (preferably a Cl-5 alkyl) or an ammonium ; G is an anion or cation such as H+, Na+, Li+, K+, NH4+ Ca Mg+2 ; Cl", Br', I', mesylate, or tosylate; and h is 0-3, preferably 0-2.

Preferred compounds within the scope of the formula I include those having linking moieties A and A'which are each independently an ester, an ether, a thio, a polyalkylene oxide, an amido, an ammonium and mixtures thereof; L and L'are each independently a Cl-25 straight chain or branched alkyl or unsubstituted aryl; and Z is a hydrogen, carboxylic acid, hydroxyl, a phosphat, a sulphonyl, a sulphate, an ammonium, a polyalkylene oxide, or a carbohydrate, preferably unsubstituted. G groups which are preferred include H+, Li+, Na+, NH+4, Cl-, Br- and tosylate.

Most preferred compounds within the scope of formula I include those compounds wherein A and A'are each independently an ester, ether, an amido, a polyoxyalkylene oxide and mixtures thereof; L and L'are each independently a Cl-20 straight chain or branched alkyl or an unsubstituted aryl; Z is a hydrogen, a phosphato, a sulphonyl, a carboxylic acid, a sulphate, a poly (alkylene oxide) and mixtures thereof; and 1S, Na or Ni4+.

Compounds of formula I are prepared by any conventional preparation method known in the art such as the one described in March, J.,"Advanced Organic Chemistry", J.

Wiley & Sons, NY (1985).

Commercially available fluorinated compounds include compounds supplied as the Zony lTM series by Dupont.

The second group of surfactants useful in the bleach composition are those compounds having a polyalkylene moiety and having a formula (II).

wherein R and R'each represent a hydrogen, a 1-5 straight chained or branched alkyl or alkylene oxide and mixtures thereof; i is 1 to 50, preferably 1 to 30, and

A, A', d, L, L', e f, n, g, o, Z, G and h are as defined above.

Preferably R and R'are each independently a hydrogen, a Cl-3 alkyl, or alkylene oxide and mixtures thereof.

Most preferably R and R'are each independently a hydrogen, 1-3 alkyl and mixtures thereof. Non-limiting examples of compounds within the scope of formula II are described in WO 96/27704 Compounds of formula II may be prepared as is known in the art and as described in March et al., Supra.

Examples of commercially available compounds of formula II may be obtained as the Pluronic series from BASF, Inc.

A third group of surfactants useful in the invention contain a fluorinated oxide moiety and the compounds have a

formula : [ (CX3 (XO) r (T) s) c (A) d- [ (L) e- (A') f-] n (lut) g] Z (G) h (III) wherein XO is a halogenated alkylene oxide having Cl-6 straight or branched halocarbons, preferably Cl-3, r is 1-50, preferably 1-25, most preferably 5-20, T is a straight chained or branched haloalkyl or haloaryl, s is 0 to 5, preferably 0-3, X, A, A 1, c, d, L, Le, f, n, g, o, Z, G and h are as defined above.

Examples of commercially available compounds within the scope of formula III include those compounds supplied under the KrytoxTM series by DuPont having a formula:

wherein x is 1-50.

Other compounds within the scope of formula III are made as known in the art and described in March et al. , Supra.

The fourth group of surfactants useful in the invention include siloxanes containing surfactants of formula IV MDD*yM (IV) wherein M is a trimethylsiloxyl end group, Dx is a dimethylsiloxyl backbone which is CO2-philic and D*y is one or more methylsiloxyl groups which are substituted with a CO2-phobic R or R'group, wherein R and R'each independently have the following formula: (CH2) a (C6H4) b (A) d- [ (L) e-- (A') f-] n- (L') gZ (G) h wherein a is 1-30, preferably 1-25, most preferably 1 20,

b is 0 or 1, C6H4 is unsubstituted or substituted with a Cl-in alkyl or alkenyl, and A, A', d, L, e, f, n, L', g, Z, G and h are as defined above and mixtures of R and R'thereof.

The Dx : D*y ratio of the siloxane containing surfactants should be greater than 0.5 : 1, preferably greater than 0.7 : 1 and most preferably greater than 1: 1.

The siloxane compounds should have a molecular weight ranging from 100 to 100,000, preferably 200 to 50,000, most preferably 500 to 35,000.

Silicones may be prepared by any conventional method such as the method described in Hardman, B."Silicones"the Encyclopaedia of Polymer Science and Engineering, v. 15, 2nd Ed. , J. Wiley and Sons, NY, NY (1989).

Examples of commercially available siloxane containing compounds which may be used in the invention are those supplied under the ABIL series by Goldschmidt.

Suitable siloxane compounds within the scope of formula IV are compounds of formula V:

the ratio of x : y and y'is greater than 0. 5 : 1, preferably greater than 0. 7 : 1 and most preferably greater than 1: 1, and R and R'are as defined above.

Preferred CO2-phobic groups represented by R and R'include those moieties of the following formula: (CH2) a (C6H4) b (A) d- [ (L) e- (A') f-]- (L') gZ (G) h wherein a is 1-20, b is 0, C6H4 is unsubstituted, A, A', d, L, e, f, n, g, Z, G and h are as defined above, and mixtures of R and R'.

Particularly useful surfactants are selected from the group consisting of the classes of ethoxy modified

polydimethylsiloxanes (e. g. SilwetT surfactants from Witco), acetylenic glycol surfactants (from Air Products) and ethoxy/propoxy block copolymers (e. g. Pluronic surfactants from BASF) and mixtures thereof.

Modifier In addition to the enzyme-compatible solvent, if present, it may be desirable to include a modifier in the bleaching composition, such as water, or an organic solvent up to only about 20 wt%, and additives to boost the bleaching and or cleaning performance such as enzymes surfactants, perfumes, and antistats, each up to about 10 wt%,.

In a preferred embodiment, a modifier such as water, or a useful organic solvent may be added with the stained cloth in the cleaning drum in a small volume. Preferred amounts of modifier should be from 0.0 to about 20 wt% (weight/weight of the densified CO2), more preferably 0.001 to about 10 wt%, even more preferably 0.001 to about 5 wt%, even more preferably 0.01 to about 3 wt%, most preferably from about 0.05 to about 0.2 wt%. Preferred solvents include water, ethanol, acetone, hexane, methanol, glycols, acetonitrile, CI-io alcohols and 5-15 hydrocarbons.

Especially preferred solvents include water, ethanol and methanol. If the modifier is water, optionally 0.1 to 50% of an additional organic cosolvent may be present as described in US-A-5 858 022. In those circumstances it may be preferred to use surfactants as described in US-5 858 022 which do contain a C02 philic group.

Method of preparing the bleaching composition The oxidoreductase may be added to the bleaching composition in any suitable manner. It may added to the cleaning vessel before or after the carbon dioxide has been let in. The enzyme may also be added in any suitable form to get effective bleaching of the articles. The enzyme may

be added in the form of granules, a dispersion or a solution. Often the dispersion or solution will be formulated to increase the stability of the enzyme.

Method of Bleaching The inventive bleaching method may be used in cleaning systems with carbon dioxide such as described in US-A-5 683 473, US-A-5 676 705, US-A-5 683 977, US-5 881 577, US-A-5 158 704, US-A-5 266 205, US-A-5 858 022 and the references cited therein. According the present invention an effective dry cleaning amount of densified carbon dioxide is used.

The exact amount will depend on the volume of the vessel, pressure at which the dry cleaning is performed, number of articles and nature and quantity of stains. The skilled person will be able to determine effective dry cleaning amount of densified carbon dioxide without undue burden using the references above. Usually, the amount of carbon dioxide will correspond to a volume of from 0.1 and 500 litre, more preferably of from 0.2 to 100 litre at the operating pressure and temperature.

The bleaching method may be used to bleach and/or clean any suitable article. The items to be cleaned should be compatible with the densified carbon dioxide. Preferably, the items include garments and domestic articles with hard surfaces. The bleaching method is especially useful to clean textile articles with bleachable stains, in particular those with grass stains.

A second aspect of the invention provides a method to bleach articles characterised in that said method comprises

the step of contacting an article with a bleaching composition according the invention.

Usually, the method of bleaching comprises loading a variety of soiled articles, preferably clothing, into a vessel (preferably a pressurisable vessel) and contacting the articles with the bleaching composition comprising the oxidoreductase. The bleaching composition minus the carbon dioxide may be contacted with the soiled articles before or together with the carbon dioxide. The carbon dioxide may be introduced into the cleaning vessel as described in US-A5, 683, 473. Preferably, the carbon dioxide is introduced into the cleaning vessel which is then pressurised to a pressure in the range of about 0.1 to about 68.9 MPa and

adjusted to a temperature range of from about -78. 5OC up to about 100oC. Although it may not always be desirable, the bleaching method may be carried out in supercritical carbon dioxide where the temperature is between 31 C and 100oC, preferably between 31 C and 60oC. Often it is preferred that the carbon dioxide is in a liquid phase so the temperature is held at - 78. 5OC up to about 30oC.

Preferably the pressure range is from 0.5 to 48 MPa, more preferably from 2.1 to 41 MPa. Preferably, the temperature range is from-56. 2 to 25OC, more preferably from -25OC to 20oC. After the bleaching step, the articles may be rinsed by introducing fresh carbon dioxide into the vessel after removing the bleaching composition.

As described above, one of the advantages of the present invention is that very short bleaching times are needed to obtain good bleaching. Preferably, the articles are

contacted with the bleaching composition for less than 45 min, more preferably less than 35 min, most preferably less 25 min.

The inventive bleaching method may be used in densified carbon dioxide although in some case liquid carbon dioxide may be preferred.

Other than in the examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term"about". Similarly, all percentages are weight/weight percentages of the carbon dioxide unless otherwise indicated. If the quantity is expressed per volume of carbon dioxide (L), this is the volume carbon dioxide used during the cleaning process.

Where the term"comprising"is used in the specification or claims, it is not intended to exclude any terms, steps or features not specifically recited.

The invention is more fully illustrated by the following non-limiting examples showing some preferred embodiments of the invention.

EXAMPLES Example 1 The commercially available, bleach sensitive test cloth BC-1 and an oily tomato elefante stained test cloth were dry cleaned using liquid carbon dioxide, oxidoreductases f according to the invention.

BC-1 is a tea stained test cloth made by CFT. Four 2"X 2" swatches of a given stain cloth were placed on the stirrer of a 600 ml autoclave having a gas compressor and an extraction system. An enzyme solution and, if appropriate other additives, was placed on the bottom of the autoclave.

The cloths were allowed to move freely in the autoclave.

Good agitation was ensured by visual observation with an endoscope through a small sapphire window in the autoclave.

After placing the cloths in the autoclave, dosing of the enzyme solution and sealing it, liquid CO2 at a tank pressure of 5.86 Mpa was allowed into the system and was

cooled to reach a temperature of about 12 C at which point the liquid C02 was at a pressure of about 5. 52 MPa. The stirrer was then turned on for 15 minutes to mimic a wash cycle (300 rpm alternating 5 sec clockwise, 5 sec anti clockwise). At the completion of the wash cycle, 20 cubic feet (566 litre) of fresh CO2 were passed through the system to mimic a rinse cycle. The pressure of the autoclave was then released to atmospheric pressure and the cleaned cloths were removed from the autoclave. Two runs were performed with each system tested. To measure the extent of cleaning, the cloths were placed in a Reflectometer supplied by Colorguard. The R scale, which measures the reflection of light at 460 nm, was used to determine stain removal. Cleaning results were reported as the percent

stain removal according to the following calculation :

% stain removal = stain removed = stain applied

cleaned cloth reading-stained cloth reading x 100% unstained cloth reading-stained cloth reading

Significant stain removal was observed when the following composition was tested on a BC-1 cloth : 0.058 mg/L ARP (Arthromyces Ramosus Peroxidase) 0.5 mM H202 0.01 wt% PTP : (Phenothiazine-10-Propionic Acid; Mw: 271. 15) 0.5 wt% H20 0.4 wt% Ethanol Example 2 Significant stain removal was observed when the following composition was tested on a oily tomato stained cloth: 0.058 mg/L ARP (Arthromyces Ramosus Peroxidase) 0.5 mM H202 0.01 wt% PTP 0.1 wt% H20 0.08 wt% Ethanol Example 3 Significant stain removal was observed when the following composition was tested on a BC-1 cloth and an even better stain removal on the oily tomato stained cloth. The latter example was repeated with 3.2 wt% ethanol with similar results.

19.8 mg/L AMO (Acremonium Murorum Oxidase expressed in Aspergillus awamori) 0.01 wt% PTP

14 wt% H20 0. 4% LES (Sodium Lauryl Ether Sulphate) ex STEPAN Example 4 Significant stain removal was observed when the following composition was tested on a BC-1 cloth 0.70 mg/L CPO (Chloride Peroxidase) l. OmM H202 To this composition lOuL 50 mM Sodium Vanadate and 1.0 mL 10 mM NaCl was added.

Example 5 Significant stain removal was observed when the following composition was tested on the oily tomato stained cloth an even better stain removal was found with 1.4 wt% water.

34 mg/L Lipoxigenase (Lipoxidase Sigma L-7395 EC 1.13. 11.12, from soya bean corresponding to 13. 4*106 Units/L) 14 wt % water, 0.7 wt% ethanol Example 6 Excellent stain removal was observed when the following composition was tested on the oily tomato stained cloth.

8. 17 mg/L Glucose oxidase, (Sigma G-6891, 4. 9 mg prot./mL, 1200 units/mL from Aspergillus niger, EC 1. 1. 3. 4) 1 g/L Glucose: D- (+)-Glucose Sigma G-7528 0.2 wt% water In either of the compositions above 0.05 wt% of the

following surfactant may be used Silwet L-7602 (an organosilicone surfactant from Witco), Pluronic L-62 (an ethoxy/propoxy block copolymer from BASF) or Surfynolm 440 (an ethoxy-modified tertiary acetylenic glycol surfactant from Air Products).

Claims (13)

1. Claims 1. A bleaching composition comprising a) a bleach-effective amount of an oxidoreductase ; b) 0 to 10 wt% of a surfactant; c) less than 20 wt% of a modifier; and d) an effective dry cleaning amount of densified carbon dioxide.
2. 2. A composition according to claim 1, characterised in that the oxidoreductase is selected from oxygen oxidoreductases, hydrogen-peroxide oxidoreductases and mixtures thereof.
3. 3. A composition according to claim 2, characterised in that the oxidoreductase is selected from the group of phenol oxidases and peroxidases and mixtures thereof.
4. 4. A composition according to claim 2, characterised in that the oxidoreductase is selected from the group consisting of lipoxygenase, glucose oxidase, maltose oxidase, Accromonium Murorum Oxidase, Arthromyces Ramosus Peroxidase and Chloride peroxidase and mixtures thereof.
5. 5. A composition according to any preceding claim, characterised in that composition comprises oxidoreductase in an amount of from 1. 0*10-4 mg/L to 1. 0*103 mg/L, more

   preferably, from 1. 0*10-3 mg/L to 5. 0*102 mg/L and even more preferably from 1. 0*10-2 mg/L to 2. 0*102 mg/L carbon dioxide.
6. 6. A composition according to claim 3, characterised in that the composition further comprises is from 1 to 2000 microM, more preferably, from 5 to 1000 microM, most preferably 10 to 800 microM of an enhancer.
7. 7. A composition according to claim 3 or 6, characterised in that the oxidoreducase is a peroxidase and the

   composition further comprises from 0. 01 to 200 mM, more preferably from 0. 05 to 150 mM, most preferably from 0. 1 to 100 mM of hydrogen peroxide.
8. 8. A composition according to any preceding claim, characterised in that the composition comprises from 0.001 to 10 wt% of a surfactant.
9. 9. A composition according to claim 8, characterised in that the surfactant is represented by a formula RnZm wherein Rn is a densified CO2-philic functional group, R is a halocarbon, a polysiloxane, or a branched polyalkylene oxide and n is 1-50; Zm-is a densified CO2-phobic functional group and m is 1-50; and at pressures of 101 kPa to 68.9 MPa and temperatures of from-78. 5 to 100oC, the Rn-group is soluble in the densified carbon dioxide to greater than 10 wt. percent

   and the Zm-group is soluble in the densified carbon dioxide to less than 10 wt. percent.
10. 10. A composition according to any preceding claim, characterised in that the composition comprises 0.001 to about 10 wt% of a modifier.
11. 11. A method to bleach articles characterised in that said method comprises the step of contacting an article with a bleaching composition according to any preceding claim.
12. 12. A method according to claim 11 characterised in that the article is contacted with the composition for less than 45 min, more preferably for less than 35 min.
13. 13. A method according to claims 11 or 12 wherein the articles are textile articles, preferably with grass stains and/or oily tomato stains.