WO2009040174A1

WO2009040174A1 - Improvements relating to fabric laundering compositions comprising mild reducing agents

Info

Publication number: WO2009040174A1
Application number: PCT/EP2008/060351
Authority: WO
Inventors: Stuart Anthony Barnett; Neil Stephen Burnham; Deborah Jane Cooke; Andrew Philip Parker; Stephen John Singleton
Original assignee: Unilever Plc; Unilever N.V.; Hindustan Unilever Limited
Priority date: 2007-09-24
Filing date: 2008-08-06
Publication date: 2009-04-02

Abstract

A method of conferring a colour benefit or dye benefit to a textile during a laundry process where chemically treated water is utilised, said process comprising at least a wash step and a rinse step, comprising the steps of: i) preparing an aqueous composition comprising an active agent, ii) contacting the textile with the aqueous composition, characterised in that: a) the active agent includes a reducing agent having a reduction potential in the range of from 0 to -800 mV in reference to a normal hydrogen electrode, b) the textile article is first contacted with the aqueous composition comprising the active agent in the wash, and is contacted with further active agent in a rinse step, and, the further active agent is incorporated in a different and separate rinse-added laundry treatment composition, and, the chemically treated water comprises active chlorine species or ozone.

Description

IMPROVEMENTS RELATING TO FABRIC LAUNDERING COMPOSITIONS COMPRISING MILD REDUCING AGENTS

TECHNICAL FIELD OF THE INVENTION

The present invention relates to fabric laundering compositions, which comprise a mild reducing agent and which are suitable for domestic use in an automatic washing machine. The invention also relates to a method of imparting a fabric care benefit, particularly a colour benefit, to a textile article during such a domestic laundering process.

BACKGROUND OF THE INVENTION

The appearance of fabric such as clothing, bedding and household articles like table linen is a key area of concern to many consumers. During their normal lifetime, clothing and domestic fabrics are subjected to repeated wearing or use, washing (generally in the presence of chemicals), rinsing and drying (for example line-drying or tumble-drying). Such treatments expose the fabrics to a variety of chemical and mechanical processes, including exposure to sunlight, which lead to a progressive and generally detrimental change in fabric appearance.

Many factors are believed to contribute to this change in appearance. Suspects include mechanical or chemically induced textural changes on the fabric surface, dye loss, dye extraction, dye transfer, dye modification (particularly by the extraction, substitution or addition of metal ions) or dye degradation, soiling, abrasion and so forth. Damage is therefore believed to arise from several causes, including: loss of colour, transfer of dyes or damage leading to a perception of colour change. One such cause of fabric colour change is believed to arise from the chemical treatment of water supplies. Addition of chlorine species or ozone to the water supply is common, such treatment acts to disinfect the water supply for domestic use. However, the chemical treatment of water supplies causes damage to coloured fabrics; in particular, it causes dye degradation of coloured fabrics.

It is known to use reducing agents in combination with other components to prevent damage in the wash.

WO01/21746 (Proctor & Gamble) discloses the use of organic sulphur containing compounds having the formula R-S-R or R-S-S-R or an inorganic sulphur compound (such as a metabisulphite, thiosulphate, sulphite or bisulphite) as a bleach scavenger. These sulphur compounds are used to remove bleaches that could otherwise react with polyamine chelating agents. The polyamines are present in the composition to bind metal ions (such as copper) which could otherwise change the appearance of dyes, but are bleach sensitive and, additionally, must be present in a narrow concentration range if they are to be effective without extracting metals from the chromophores of dyes (for example from phthalocyanine dyes) and therefore themselves becoming detrimental. By pre-treating the fabrics with a substantive bleach scavenger the effect of a later exposure to bleach on the effectiveness of polyamines can be reduced, enabling polyamines to be used at an effective but non-damaging level. Optional components of the formulations disclosed include chlorine scavengers, such as ammonium salts (ammonium chloride being particularly preferred).

WO2004/038084 (The Clorox Company) discusses many causes of fabric fading and proposes a composition which seeks to protect clothing and domestic textiles against the combined effects of wear, fading, chlorine damage, dye-transfer and re-deposition. This is done by the use of a dye-transfer inhibitor which is present at a level effective to prevent dye transfer but not so high that it extracts dye from the articles being laundered. Suitable compositions comprise one of each of UV protectants, enzymes and dye-transfer inhibitors, together with optional components selected from: solubilisers, lubricants, sequestrants, chlorine and/or active oxygen scavengers, crystal growth inhibitors etc. Examples of suitable active oxygen/chlorine scavengers include sodium thiosulphate (a reductant), butylated hydroxytoluene and butylated hydroxyanisole (BHT and BHA, both antioxidants) and enzymes having the activity of Catalase. Hydroxyamine chlorine/chloride scavengers are preferred and, given that the composition comprises an enzyme, lysine reducing anions such as sulphite, bisulphite, thiosulphate and nitrite should be avoided.

US2004/038852 (Proctor & Gamble) discloses the use of a high level of a chlorine scavenger in a liquid laundry detergent composition in combination with a polymeric dye transfer inhibitor and a surfactant and in the absence of more than 0.02% of a thazinylaminostilbene optical brightener. It is believed that using a washing composition which comprises this specific combination (including a high level of chlorine scavenger) ensures that sufficient chlorine scavenger is carried over from the wash (to which the liquid composition is added) into the rinse. Suitable chlorine scavengers comprise trivalent nitrogen species; reducing species such as sulphite, bisulphite, thiosulphite, thiosulphate, iodide, nitrite; antioxidants and a range of other materials.

Despite these proposals, there still remains a need to reduce and preferably eliminate the colour change problems experienced by consumers due to laundering their textile garments and articles in chemically treated water.

BRIEF DESCRIPTION OF THE INVENTION

While the prior art teaches the use of mixtures of materials in a 'one-shot' addition, we have now found that the addition of a suitable agent or agents both to the main - A -

wash liquor and also to at least one of the rinse liquors results in an advantageous reduction of oxidative processes affecting fabric in a simple and highly effective manner.

Accordingly, the present invention provides a method of conferring a colour benefit or dye benefit to a textile during a laundry process where chemically treated water is utilised, said process comprising at least a wash step and a rinse step, comprising the steps of:

i) preparing an aqueous composition comprising an active agent, ii) contacting the textile with the aqueous composition,

characterised in that:

a) the active agent includes a reducing agent having a reduction potential in the range of from 0 to -800 mV in reference to a normal hydrogen electrode, b) the textile article is first contacted with the aqueous composition comprising the active agent in the wash, and is contacted with further active agent in a rinse step, and,

the further active agent is incorporated in a different and separate rinse-added laundry treatment composition, and, the chemically treated water comprises active chlorine species or ozone.

By ensuring contact of this specific reducing agent with fabric during at least a wash and rinse step of the laundry process, an unexpectedly high colour change benefit is obtained. This does not require any reliance on ensuring adequate and selective carry-over of already dissolved materials from the wash to the rinse. Details of the normal hydrogen electrode can be found in: "Encyclopaedia of Analytical Chemistry: Applications, Theory & Instrumentation", R.A. Meyers, 2000 Vol.2 pp 1258-1259 (Published by John Wiley & Sons, ISBN 0471976709).

A list of redox potentials measured using this technique can be found in the "CRC Handbook of Chemistry and Physics", 86th Edition pp 8.20 - 8.29 (Published by CRC, ISBN 0849304865). Thiosulphate, a preferred reducing agent, is listed at - 571 mV.

As will be described in further detail below, the reducing agent may be released together with other components, for example, colour care benefit agents, preferably selected from sequestrants, dye transfer inhibitors, cellulases, fluorescers and anti-abrasion polymers such as certain polysaccharides, an example of which is HEC (hydroxyethylcellulose).

DETAILED DESCRIPTION OF THE INVENTION

As outlined above, the present invention is based on the surprising finding that the presence of a mild reducing agent or agents that can act as oxygen scavengers or chlorine neutralisers, especially those that are capable of removing oxidising species and/or oxidation catalysts, in certain stages of a domestic wash cycle (i.e. both the main wash and at least one of the rinse stages) produces an unexpectedly large reduction in fabric colour change when compared to addition of the agent or agent(s) in only one step of a laundry process (i.e. just the main wash).

The Chemically Treated Water

The water used in the laundry process of the current invention is chemically treated. By this we mean that the used is treated with an active chlorine agent or ozone. This means that the water used in the method comprises a certain level of active chlorine species or ozone. The chemical treatment of water is generally carried out by the relevant water supplier. Levels of active chlorine species or ozone present in the water supply vary. However, the invention is particularly suitable for use with chemically treated water comprising active chlorine species or ozone at a level of from 0.01 to 5ppm (parts per million), preferably from 0.01 to 3ppm.

The active chlorine species include, for example, chlorine dioxide, hypochlorite (and various salts thereof) and chlorine itself, as well as their associated breakdown products.

The Laundry Process

The method of the invention is applied to a textile article, preferably a non- keratinaceous textile article, more preferably a cellulosic or cellulose containing textile article. Cotton articles (such as "Denim Jeans") are known to be particularly sensitive to colour changes (generally known as "fading") following extended laundering.

The laundry process to which the method of the present invention applies can be any laundry process comprising a wash and a rinse step. The process may be manual, such as hand-washing or, more preferably, semi-automatic or automatic such as performed by an automatic washing machine.

The laundry process comprises at least one main wash step and a rinse step. Typically, there will be more than one rinse step. Thus a laundry process according to the present invention preferably comprises a main wash step, at least one, preferably two, most preferably three or more intermediate rinse steps and a final rinse step. The laundry process is preferably facilitated by an automatic washing machine. Such a laundry process typically comprises at least one main wash step, in which textile articles are contacted with the or each main wash liquor. This liquor comprises an aqueous solution or dispersion of a main wash detergent product. In some machines facility is provided for a 'pre-wash' during which detergent may or may not be added.

At the end of the main wash, the main wash liquor is usually drained from the machine and one or more rinses takes place. Typically a series of sequential rinses takes place, culminating in a final rinse.

A number of machines employ alternative processes. One such process differs in that the first rinse is added to the machine drum without draining the wash liquor. Subsequent rinses can then be employed in a similar fashion to a normal wash process. In other machines the number of rinses may be determined by the level of materials in the rinses. In such machines the number of rinses may vary with the washload.

Machine rinses involve the intake of water into the machine and the contacting of the textile articles with this water. The intake of water in the rinse can be in any conventional fashion, such as flood filling the washing vessel. Machines are known whereby the intake of water is done by spraying said water into the washing vessel.

As used herein, the term "rinse liquor" refers to the rinse water. Each rinse is usually drained from the machine before the next rinse is applied, although as noted above, alternative processes are known whereby the first rinse can be added to the machine without draining the wash liquor - draining and subsequent rinses can then follow. As used herein, the term "intermediate rinse" means a rinse which is not the final rinse of the laundry process and the term "final rinse" means the last rinse in the series of rinses.

In a typical automatic washing machine laundry process, a composition comprising a benefit agent, such as a rinse conditioner, is added to the final rinse only.

The reducing agent is preferably present both in the, or each, main wash and preferably throughout the rinses, or in at least one of the rinses. The present invention is not concerned with those instances where the reducing agent is only present in the main wash, or only present in the final rinse.

Employing both a rinse conditioner containing a reducing agent and a main wash detergent containing a reducing agent will ensure that the reducing agent is present in the main wash and the final rinse. This will have some benefit, but during the intermediate rinses the reducing agent will be removed unless supplemented.

The Aqueous Composition

In the method of the invention, the aqueous composition (be it main wash liquor or rinse liquor) comprises the reducing agent which is described in further detail below. Other materials, in addition to the reducing agent, may optionally be present in the aqueous composition and these are referred to collectively herein as the "active agent". As will be understood, the "active agent" may comprise only the reducing agent. Additional optional additional components of the "active agent", as described in more detail below, may include colour care benefit agents, examples of which include sequestrants, dye transfer inhibitors, cellulases, fluorescers and anti-abrasion polymers such as certain polysaccharides, and example of which is HEC (hydroxyethylcellulose). The concentration of the reducing agent in the aqueous composition is at a level of at least 0.0001 g/l, preferably between 0.0001 and 5 g/l, more preferably between 0.001 and 2 g/l and most preferably between 0.005 and 2 g/l in each liquor to which the active agent is applied (i.e. the main wash liquor, intermediate or final rinse liquor).

Mode of Addition

The term "active agent" as used herein includes the "further active agent", unless otherwise stated. As noted above, the active agent may be simply the reducing agent or it may, in addition, comprise other beneficial components.

During the method of the invention, the active agent is comprised in an aqueous composition as described above. This aqueous composition comprising the active agent is prepared by the dissolution or dispersion of the active agent in the wash or rinse liquor. Prior to said dissolution/dispersion, the active agent may exist in any suitable form.

The method of the invention requires that an aqueous composition comprising the mild reducing agent is contacted with a textile during a wash step. The textile is contacted with further active agent (comprising a mild reducing agent) from a separate and different rinse-added composition during a rinse step.

Various compositions may be used to supply the active agent during each step, this may be simply be a aqueous dispersion/solution of the active agent in water, or the active agent comprising the mild reducing agent may be supplied from full detergent/rinse laundry formulations. Preferred formats are that the active agent is:

a) included in a composition, for example a laundry detergent or rinse conditioner composition, which may be a powder, liquid, gel or tablet composition; b) encapsulated in a capsule or capsules, immobilised in a suitable carrier or matrix, for example in a slow release formulation; c) held on a support; or, d) simply used as the neat compound itself, with or without other components.

Any combination of these forms may be used to provide the active agents at different stages in the wash process.

In one simple format, the active agent and further active agent can be added to the wash or rinse liquor manually, for example during hand washing or a semiautomatic washing process. Examples of manual addition include adding the active agent manually into the drawer, or using a scoop or a jug to add a measured quantity of the active agent directly into the wash or into one or more rinse liquors. The scoop or jug may be calibrated.

The active agent may be added to the wash or rinse liquor by means of automatic dosing by a washing machine with automatic dosing functionality. Ideally, addition should be to every wash stage including the, or each, main wash and all the rinses.

This may be accomplished in various ways, i.e. by modification of the washing machine design such that the machine comprises specific dispensing means to ensure that materials are added to the water being supplied into the washing drum. An example of such a modification is where the dispensing means are arranged either within the machine in the drum or sump, or otherwise between the water inlet and the drum.

Addition of active agent to the water supply can also be accomplished outside of the washing machine. For example, the dispensing means may be arranged outside the machine by attachment of the dispensing means to the water inlet of the machine. This dispensing means does not have to be part of the machine, it may be a separate component attached at any point to the water inlet of the washing machine.

Dispensing means may be replaceable or renewable by addition of fresh active agent, for example in the form of a replaceable cartridge.

As washing machines are supposed to last for a number of years it is preferable to provide means to ensure that the present invention can be put into effect with an existing washing machine.

The active agent, in whichever form, may be contained in a dispensing device. The dispensing device may be suitable for use in the drum or the drawer of a washing machine. It may be attached to the interior of the drum, or the sump of the washing machine, or attached to the water inlet (either inside the machine or outside the machine) so as to come into contact with the water for the wash or rinse liquor before the water enters the drum of the washing machine. This may either be used for a single or a plurality of washes and in either case may be consumed entirely (such as a tablet or granular composition) or partially (such as a 'shuttle'). In the case of a dispensing device attached to the water inlet of the machine it is convenient that the device can be bypassed if the user wishes to employ a bleaching composition although this is not strictly necessary if a sufficient excess of bleach is present. In one preferred embodiment, the active agent is added by means of a dispensing device containing said agent immobilised in a 'slow-release' formulation. The slow release formulation preferably comprises a carrier material for the active agent. Preferably the carrier material is at best sparingly soluble in the wash or rinse liquor.

Contact with the further active agent means that a separate rinse-added composition comprising the mild reducing agent is added to a rinse step and contacted with the fabric.

The compositions used can be slow release compositions, in that they can replenish or increase the concentration of active agent in the aqueous composition during the laundry process. The replenishment typically occurs when fresh water is taken into the washing process and comes into contact with the source of active agent thus causing dissolution of a quantity of the agent into the water. Thus the active agent is slowly released into the liquor through all or part of the laundry process. The present invention does not rely on carry-over of already dissolved reducing agent from the wash into subsequent stages of the laundry process.

During use in an automatic washing machine, the active agent may be immobilised in a slow release matrix, whereby dissolution and/or dispersion into the wash or rinse liquor takes place when the water for a main wash or rinse is taken in by the machine and contacts the immobilised formulation.

A poly[ethylene glycol] (PEG) based carrier material is used in a preferred embodiment of the invention. The amount of the active agent within the PEG carrier is such that the concentration of active agent present in the wash liquor or rinse liquor is such that the concentration of reducing agent is at least 0.0001 g/l, preferably between 0.0001 and 5 g/l, more preferably between 0.001 and 2 g/l and most preferably between 0.005 and 2 g/l.

One preferred dispensing device is a dispensing ball or 'shuttle', more preferably a dual or multi compartment dispensing device. The dual or multi-compartment dispensing device comprises the active agent immobilised on a carrier material with one or more separate compartments available for the incorporation of a solid or liquid detergent in a separate compartment of the device to the slow release active agent formulation.

The dispensing device can be tailored for a single use, i.e. for a single wash with one or more rinse cycles. Alternatively, the dispensing device can be tailored for use on multiple occasions, i.e. numerous wash and rinse cycles. In this case, the dispensing device will preferably take the product form of a slow release dispensing device present in the main wash drum, tray or sump of the washing machine.

By slow release is meant a means by which addition of the active agent to the wash or rinse liquor is allowed to progress in portions over time. This can be through an automatic dosing device either as part of the washing machine, or exterior to the washing machine. Preferably the means for slow release is through a device which allows for constant contact between the wash or rinse liquor and the slow release device. More preferred is a device which allows constant contact between a constant available surface-area of the active agent immobilised on a carrier material.

This ensures that under the same conditions, the same amount of active agent can be dispensed each time. A person skilled in the art will know that the main wash liquor and rinse liquor will have different properties (temperature of the liquor, presence of additional chemicals in the wash liquor (depending on the detergent product used), different volumes of water), and so the amount of active agent so dispensed will differ between a main wash and a rinse step. Nevertheless, the preferred embodiment of the product is formulated so that the active agent is dispensed from the slow release formulation in an amount such that the reducing agent is maintained at a level of at least 0.0001 g/l, preferably between 0.0001 and 5 g/l, more preferably between 0.001 and 2 g/l and most preferably between 0.005 and 2 g/l.

It is also envisaged that the present invention may be put into effect by means of a so-called "smart shuttle". In such a device, which may include means for measuring parameters of the liquor, release of materials occurs when predetermined conditions are met. A device of this general description is disclosed in US 2004/0088796.

The Reducing Agent

As noted above the active agent for use in the present invention always includes a mild reducing agent which is believed to act as an oxygen scavenger or a chlorine neutraliser.

The active agent is believed to remove oxidising agents from the laundry process environment, or to reduce oxidation catalysts to a non-catalytic oxidation state, or otherwise neutralise the active chlorine species or ozone present in the water supply. The further active agent is defined in the same way as the active agent.

During the method of the invention, the further active agent may be the same material as the active agent (which is preferred), or may be a different one. In either case it will still comprise a mild reducing agent. Preferred reducing agents are selected from the group consisting of the soluble, preferably alkali and alkaline earth metal, salts of thiosulphate, sulphite, bisulphite and metabisulphite anions.

The preferred reduction potential of the reducing agent is in the range of from - 500 to -600 mV in reference to a normal hydrogen electrode.

The most preferred reducing agent is a soluble thiosulphate salt, most preferably the sodium salt. Sodium thiosulphate is relatively inexpensive, readily soluble, effective and can be incorporated into detergent formulations without difficulty.

Optional Sequestrants

The active agent may also additionally comprise a transition metal sequestrant. This acts to bind transition metals present in the wash or rinse liquor so as to suppress their capacity to either catalyse undesirable oxidation reactions, deposit on fabrics or to undesirably interact with dyes on fabrics.

Preferred sequestrants are those that will bind transition metal ions, especially iron and copper. Although many common sequestrants used in the laundry detergent industry have the potential to bind said transition metal ions and so will have some degree of effectiveness, preferred sequestrants are transition metal chelating agents. These chelating agents typically have two or more groups present that can bind to the transition metal ion.

Generally, chelating agents suitable for use herein can be selected from the group consisting of aminocarboxylates, aminophosphonates, polyfunctionally-substituted aromatic chelating agents and mixtures thereof. Without intending to be bound by theory, it is believed that the benefit of these materials is due in part to their exceptional ability to remove heavy metal ions from washing solutions by formation of soluble chelates; other benefits include inorganic film or scale prevention. Other suitable chelating agents for use herein are the commercial DEQUEST series, and chelants from Monsanto, DuPont, and Nalco, Inc.

Aminocarboxylates useful as optional chelating agents include:

ethylenediaminetetracetates,

N-hydroxyethylethylenediaminetriacetates, nithlotriacetates, ethylenediaminetetraproprionates, triethylenetetraaminehexacetat.es, diethylenetriaminepentaacetates, and, ethanoldiglycines, preferably as the alkali metal, ammonium, and substituted ammonium salts thereof and mixtures thereof.

Aminophosphonates are also suitable for use as chelating agents in the compositions of the invention when at least low levels of total phosphorus are permitted in detergent compositions, and include ethylenediaminetetrakis (methylenephosphonates). Preferably, these amino-phosphonates do not contain alkyl or alkenyl groups with more than about 6 carbon atoms.

Polyfunctionally-substituted aromatic chelating agents are also useful in the compositions herein. See U.S. Patent 3,812,044. Preferred compounds of this type in acid form are dihydroxydisulfobenzenes such as 1 ,2-dihydroxy-3,5- disulfobenzene.

A chelator for use herein is ethylenediamine disuccinate ("EDDS"), especially (but not limited to) the [S₁S] isomer as described in U.S. Patent 4,704,233. The trisodium salt is preferred though other forms, such as magnesium salts, may also be useful. Optional Additional Colour Care Benefit Agents

The active agent may additionally comprise one or more colour care benefit agents, examples of which include sequestrants, dye transfer inhibitors, cellulases, fluorescers and anti-abrasion polymers such as certain polysaccharides, one example being hydroxyethylcellulose (HEC).

These materials are believed to prevent perceived or real colour loss by reducing damage to the articles being laundered.

Preferred colour care benefit agents are polysaccharides. Typically, the wash/rinse liquor will comprise around 0.01 g/L of a polysaccharide colour care benefit agent.

Preferably the polysaccharide is a beta 1 -4 polysaccharide; more preferably a cellulose derivative. Cellulose derivatives are widely available.

Preferably the polysaccharide is a hydroxy C2-C4 alkyl derivative. More preferably the hydroxy C2-C4 alkyl derivative is a hydroxy ethyl derivative.

In a preferred embodiment the polysaccharide is the hydroxy-alkyl ether of cellulose. This material is not only commonly available, but also shows excellent lubrication benefits.

Preferably the degree of substitution (DS) of the polysaccharide is 1 -3, more preferably 1.5-2.25. Most preferably the DS falls in the range 1.5-2.0. Lower DS levels have poor water solubility, which appears to be important for the colour care benefit. Higher levels appear to lead to problems with particulate soil redeposition. Preferably the molecular weight of the polysaccharide is 100,000 to 500,000 Dalton, preferably less than 300,000 Dalton. The polysaccharide is preferably such that viscosity of the material is 300-400 cps at 2% solution (measured on a Brookfield viscometer using ASTM D2364). The solution viscosity under standard conditions is related to the molecular weight of the polysaccharide, and the preferred materials have nearly Newtonian viscosity profiles between 1 and 10 reciprocal seconds.

Suitable hydroxy C2 alkyl derivatives of cellulose are available in the marketplace from Dow under the trade name "Cellosize" and from Hercules under the trade name "Natrasol".

Preferred dosage levels are such that the concentration of the 1 -4 beta polysaccharide is 0.01-0.06 g/L. In typical European was conditions the dosage of a laundry product is 7g/L in about 8-15 litres of water depending on the machine and load.

Preferably the level of polysaccharide is 0.1 -3%wt on full formulated product, more preferably 0.2-0.8%wt. In this specification, all percentages are weight percentages unless otherwise stated. A typical product would contain 0.5%wt of the polysaccharide which would give an in use concentration of around 0.035g/L.

The colour care benefit agent may be present together with the reducing agent as part of the active agent which is maintained at some level throughout the main wash and at least one subsequent rinse or it may be present in the balance of a main-wash composition which is removed in the rinse. Other Components

As noted above the present invention may be embodied as a fully functional laundry detergent composition and rinse-added composition. In such cases the usual components of such a detergent composition will typically be present. Typically these include one or more of surfactants, hydrotropes, preservatives, fillers, builders, complexing agents, polymers, stabilizers, enzymes and perfumes. These are described briefly below. The composition may also be a rinse-added composition such as a rinse conditioner. Typical constituents of such are also described.

Surfactants

The surfactants may be non-ionic including semi-polar and/or anionic and/or cationic and/or zwitterionic.

The surfactants may be present in the composition at a level of from 0.1 % to 75% by weight.

When included therein the composition usually contains from about 1 % to about 40% of an anionic surfactant such as:

linear alkylbenzenesulfonate, alpha-olefinsulfonate, alkyl sulfate (fatty alcohol sulfate), alcohol ethoxysulfate, secondary alkanesulfonate, alpha-sulfo fatty acid methyl ester, alkyl- or alkenylsuccinic acid, soap, and, mixtures thereof.

Preferred surfactants are alkyl ether sulphates and blends of alkoxylated alkyl nonionic surfactants with either alkyl sulphonates or alkyl ether sulphates. Preferred alkyl ether sulphates are C8-C15 alkyl and have 2-10 moles of ethoxlation. Preferred alkyl sulphates are alkylbenzene sulphonates, particularly linear alkylbenzene sulphonates having an alkyl chain length of C8-C15. The counter ion for anionic surfactants is typically sodium, although other counter-ions such as TEA or ammonium can be used. Suitable anionic surfactant materials are available in the marketplace as the 'Genapol'™ range from Clariant.

When included therein the composition usually contains from about 0.2% to about 60% of a non-ionic surfactant such as:

alcohol ethoxylate, nonylphenol ethoxylate, alkylpolyglycoside, alkyldimethylamineoxide, ethoxylated fatty acid monoethanolamide, fatty acid monoethanolamide, polyhydroxy alkyl fatty acid amide, N-acyl N-alkyl derivatives of glucosamine ("glucamides"), and, mixtures thereof.

Preferred nonionic surfactants include the primary and secondary alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C10-C15 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol.

Higher levels of surfactant may be employed (up to almost 100%) but this can leave little space in the formulation for builders and other components and may lead to a sticky product which requires special processing.

As the purpose of the rinse is to remove surfactant and soil it is not preferable that surfactant is present as part of the "active agent". Hvdrotropes/Sol vents

The term "hydrotrope" generally means a compound with the ability to increase the solubilities, preferably aqueous solubilities, of certain slightly soluble organic compounds. Examples of hydrotropes include sodium xylene sulfonate. The composition may comprise a solvent such as water or an organic solvent such as isopropyl alcohol or glycol ethers. Solvents are typically present in liquid or gel compositions.

Builders or Complexing Agents

Builder materials may be selected from 1 ) calcium sequestrant materials, 2) precipitating materials, 3) calcium ion-exchange materials and 4) mixtures thereof.

Examples of calcium sequestrant builder materials include alkali metal polyphosphates, such as sodium thpolyphosphate and organic sequestrants, such as ethylene diamine tetra-acetic acid.

Examples of precipitating builder materials include sodium orthophosphate and sodium carbonate.

Examples of calcium ion-exchange builder materials include the various types of water-insoluble crystalline or amorphous aluminosilicates, of which zeolites are the best known representatives, e.g. zeolite A, zeolite B (also known as zeolite P), zeolite C, zeolite X, zeolite Y and also the zeolite P-type as described in EP-A- 0,384,070.

The composition may also contain 0-65% of a builder or complexing agent such as: ethylenediaminetetraacetic acid, diethylenetriamine-pentaacetic acid, alkyl- or alkenylsuccinic acid, nitrilotriacetic acid, or, mixtures thereof.

Many builders also give some colour benefits by virtue of their ability to complex metal ions. Some builder may therefore be present as part of the "active agent".

Where builder is present, the compositions may suitably contain less than 20%wt, preferably less than 10% by weight, and most preferably less than 10%wt of detergency builder. The composition may contain as builder a crystalline aluminosilicate, preferably an alkali metal alumino-silicate, more preferably a sodium aluminosilicate. This is typically present at a level of less than 15%wt.

Aluminosilicates are materials having the general formula:

0.8-1.5 M₂O. AI₂O₃. 0.8-6 SiO₂

where M is a monovalent cation, preferably sodium. These materials contain some bound water and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g. The preferred sodium aluminosilicates contain 1.5-3.5 SiO₂ units in the formula above. They can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply described in the literature. The ratio of surfactants to alumuminosilicate (where present) is preferably greater than 5:2, more preferably greater than 3:1.

Alternatively, or additionally to the aluminosilicate builders, phosphate builders may be used. In this art the term 'phosphate' embraces diphosphate, triphosphate, and phosphonate species. Other forms of builder include silicates, such as soluble silicates, metasilicates, layered silicates (e.g. SKS-6 from Hoechst). For low cost formulations carbonate (including bicarbonate and sesquicarbonate) and/or citrate may be employed as builders.

Polymers

The composition may comprise one or more polymers, for example: carboxymethylcellulose, poly(vinylpyrrolidone), poly (ethylene glycol), polyvinyl alcohol), poly(vinylpyridine-N-oxide), poly(vinylimidazole), polycarboxylates (such as polyacrylates, maleic/ acrylic acid copolymers and lauryl methacrylate/acrylic acid copolymers), and, mixtures thereof.

Modern detergent compositions typically employ polymers as so-called 'dye- transfer inhibitors'. These prevent migration of dyes, especially during long soak times. Any suitable dye-transfer inhibition agents may be used in accordance with the present invention.

Generally, such dye-transfer inhibiting agents include: polyvinyl pyrrolidone polymers, polyamine N-oxide polymers, copolymers of N-vinylpyrrolidone and N-vinylimidazole, manganese pthalocyanine, peroxidases, and, mixtures thereof.

Nitrogen-containing, dye binding, DTI polymers are preferred. Of these polymers and co-polymers of cyclic amines such as vinyl pyrrolidone, and/or vinyl imidazole are preferred.

Polyamine N-oxide polymers suitable for use herein contain units having the following structural formula: R-A_x-P; wherein P is a polymehzable unit to which an N-O group can be attached or the N-O group can form part of the polymerizable unit; A is one of the following structures: -NC(O)-, -C(O)O-, -S-, -O-, -N=; x is 0 or 1 ; and R is an aliphatic, ethoxylated aliphatic, aromatic, heterocyclic or alicyclic group or combination thereof to which the nitrogen of the N-O group can be attached or the N-O group is part of these groups, or the N-O group can be attached to both units. Preferred polyamine N-oxides are those wherein R is a heterocyclic group such as pyridine, pyrrole, imidazole, pyrrolidine, piperidine and derivatives thereof. The N-O group can be represented by the following general structures: N(O)(R')o-3, or =N(O)(R')o-i, wherein each R' independently represents an aliphatic, aromatic, heterocyclic or alicylic group or combination thereof; and the nitrogen of the N-O group can be attached or form part of any of the aforementioned groups. The amine oxide unit of the polyamine N-oxides has a pKa<10, preferably pKa<7, more preferably pKa<6.

Any polymer backbone can be used provided the amine oxide polymer formed is water-soluble and has dye transfer inhibiting properties. Examples of suitable polymeric backbones are polyvinyls, polyalkylenes, polyesters, polyethers, polyamides, polyimides, polyacrylates and mixtures thereof. These polymers include random or block copolymers where one monomer type is an amine N- oxide and the other monomer type is an N-oxide. The amine N-oxide polymers typically have a ratio of amine to the amine N-oxide of 10:1 to 1 :1 ,000,000. However, the number of amine oxide groups present in the polyamine oxide polymer can be varied by appropriate copolymehzation or by an appropriate degree of N-oxidation. The polyamine oxides can be obtained in almost any degree of polymerization. Typically, the average molecular weight is within the range of 500 to 1 ,000,000; more preferably 1 ,000 to 500,000; most preferably 5,000 to 100,000. This preferred class of materials is referred to herein as "PVNO". A preferred polyamine N-oxide is poly(4-vinylpyhdine-N-oxide) which as an average molecular weight of about 50,000 and an amine to amine N-oxide ratio of about 1 :4.

Copolymers of N-vinylpyrrolidone and N-vinylimidazole polymers (as a class, referred to as "PVPVI") are also preferred. Preferably the PVPVI has an average molecular weight range from 5,000 to 1 ,000,000, more preferably from 5,000 to 200,000, and most preferably from 10,000 to 20,000, as determined by light scattering as described in Barth, et al., Chemical Analysis, Vol. 113. "Modern Methods of Polymer Characterization". The preferred PVPVI copolymers typically have a molar ratio of N-vinylimidazole to N-vinylpyrrolidone from 1 :1 to 0.2:1 , more preferably from 0.8:1 to 0.3:1 , most preferably from 0.6:1 to 0.4:1. These copolymers can be either linear or branched. Suitable PVPVI polymers include Sokalan™ HP56, available commercially from BASF, Ludwigshafen, Germany. Also preferred as dye transfer inhibition agents are polyvinylpyrrolidone polymers ("PVP") having an average molecular weight of from about 5,000 to about

400,000, preferably from about 5,000 to about 2000,000, and more preferably from about 5,000 to about 50,000. PVP's are disclosed for example in EP-A- 262,897 and EP-A-256,696. Suitable PVP polymers include Sokalan(TM) HP50, available commercially from BASF. Compositions containing PVP can also contain polyethylene glycol ("PEG") having an average molecular weight from about 500 to about 100,000, preferably from about 1 ,000 to about 10,000. Preferably, the ratio of PEG to PVP on a ppm basis delivered in wash solutions is from about 2:1 to about 50:1 , and more preferably from about 3:1 to about 10:1.

Also suitable as dye transfer inhibiting agents are those from the class of modified polyethyleneimine polymers, as disclosed for example in WO-A-0005334. These modified polyethyleneimine polymers are water-soluble or dispersible, modified polyamines. Modified polyamines are further disclosed in US-A-4,548,744; US-A- 4,597,898; US-A- 4,877,896; US-A- 4,891 , 160; US-A- 4,976,879; US-A- 5,415,807; GB-A-1 ,537,288; GB-A-1 ,498,520; DE-A-28 29022; and JP-A- 06313271.

Preferably the composition according to the present invention comprises a dye transfer inhibition agent selected from polyvinylpyrridine N-oxide (PVNO), polyvinyl pyrrolidone (PVP), polyvinyl imidazole, N-vinylpyrrolidone and N- vinylimidazole copolymers (PVPVI), copolymers thereof, and mixtures thereof.

The amount of dye transfer inhibition agent in the composition according to the present invention will be from 0.01 to 10%, preferably from 0.02 to 5%, more preferably from 0.03 to 2%, by weight of the composition.

As mentioned above polymeric dye transfer inhibitors may be present either in the active agent which is maintained at some level throughout the wash and some or all of the subsequent rinses or in the balance of the composition which is released in the main wash and lost in subsequent rinses.

Enzymes

Additional colour benefits can be obtained by the incorporation of enzymes. Enzymes contemplated for use in laundry detergent compositions include proteases, alpha-amylases, cellulases, lipases, peroxidases/oxidases, pectate lyases, mannanases, or mixtures thereof.

Cellulases have been proposed as enzymes which give a colour/appearance benefit. Suitable cellulases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included.

It is envisaged that suitable cellulases will be found among cellulases from the genera Bacillus, Pseudomonas, Humicola, Fusahum, Thielavia, Acremonium, e.g. the fungal cellulases produced from Humicola insolens, Thielavia terrestris, Myceliophthora thermophila, and Fusarium oxysporum disclosed in US 4,435,307, US 5,648,263, US 5,691 ,178, US 5,776,757, WO 89/09259, WO 96/029397, and WO 98/012307. Especially suitable cellulases are the alkaline or neutral cellulases with color care benefits. Examples of such cellulases are cellulases described in EP 0 495 257, EP 0 531 372, WO 96/11262, WO 96/29397, WO 98/08940. Other examples are cellulase variants such as those described in WO 94/07998, EP 0 531 315, US 5,457,046, US 5,686,593, US 5,763,254, WO 95/24471 , WO 98/12307 and PCT/DK98/00299.

Commercially available cellulases include Celluzyme™, Carezyme™, Endolase™, Renozyme™ (Novozymes A/S), Clazinase™ and Puradax HA™ (Genencor International Inc.), and KAC-500(B)™ (Kao Corporation).

Stabilizers

Any enzyme present in the composition may be stabilized using conventional stabilizing agents, e.g., a polyol such as propylene glycol or glycerol, a sugar or sugar alcohol, lactic acid, boric acid, or a boric acid derivative, e.g., an aromatic borate ester, or a phenyl boronic acid derivative such as 4-formylphenyl boronic acid, and the composition may be formulated as described in e.g. WO 92/19709 and WO 92/19708.

Other Detergent Ingredients

The composition may also contain other conventional detergent ingredients such as e.g. fabric conditioners including clays, foam boosters, suds suppressors (anti- foams), anti-corrosion agents, soil-suspending agents, anti-soil redeposition agents, dyes, anti-microbials, tarnish inhibitors, or perfumes. Rinse Conditioners

For the rinse added composition, preferably the composition comprises a cationic compound.

Preferred cationic compounds are quaternary ammonium compounds.

It is advantageous if the quaternary ammonium compound is a quaternary ammonium compound having at least one C12 to C22 alkyl chain.

It is preferred if the quaternary ammonium compound has the following formula:

in which R¹ is a C12 to C22 alkyl or alkenyl chain; R², R³ and R⁴ are independently selected from Ci to C₄ alkyl chains and X^" is a compatible anion. A preferred compound of this type is the quaternary ammonium compound cetyl trimethyl quaternary ammonium bromide.

A second class of possible materials are the quaternary ammonium of the above structure in which R¹ and R² are independently selected from C12 to C22 alkyl or alkenyl chain; R³ and R⁴ are independently selected from Ci to C₄ alkyl chains and X^" is a compatible anion.

Other suitable quaternary ammonium compounds are disclosed in EP 0 239 910 (Proctor and Gamble). The cationic compound may be present from 1.5 wt % to 50 wt % of the total weight of the composition. Preferably the cationic compound may be present from 2 wt % to 25 wt %, a more preferred composition range is from 5 wt % to 20 wt %.

Where the present invention comprises a main wash detergent and a rinse conditioner which both provide the reducing agent (thus ensuring that it is present through a significant part of the wash process) the products are preferably provided with instructions that they are to be used together. These instructions may be provided on one of the products or both. The products may be provided as a kit together with these instructions.

In order that the invention may be further understood and carried forth into practice it will be described below with reference to non-limiting examples.

Examples

Example 1 - Demonstration of the dye degradation effect of active chlorine species on dyed fabrics

The link between dye degradation in solution and dye on fabric is proposed in the paper "Influence of Surfactants on Homogeneous and Heterogeneous Oxidation of Azo Dyes", J. Oakes, American Dyestuff Reporter Nov.2000 pp 47-52

Thus the data in table 1 , which shows the degradation of dye in solution, equates to a showing that dye degradation applies to dyes on fabric.

Table 1 - The effects of hypochlorite concentration, pH and temperature on dye degradation

From the data in table 1 , it is clear that higher hypochlorite concentration causes higher dye degradation. It is also apparent that this effect is increased at higher temperature, and the effect is demonstrated at wash pH (generally around pH 10) as well as rinse pH (usually from pH 7-5). Example 2 - Demonstration of the beneficial effect of adding a mild reducing agent in the method according to the invention.

The water was used had an active chlorine species content of 0.2ppm

Examples were carried out in a Miele Novotronic W980 washing machine. The wash program used was as follows:

Main wash - 40⁰C, 15 litres Wirral water, 35 minutes • Four rinses - ambient temperature, 21 litres Wirral water, 120 seconds per rinse

60 second distribution spin at 90rpm

120 second spin @ 400rpm

300 second spin at 1200rpm 60 second distribution spin at 90rpm

The detergent composition used (110g) was Persil Colour sourced direct from Lever in May 2006 (identical to that available in the marketplace).

Loads comprised dyed mercerised woven cotton sheeting cloths: twelve in total, two panels for each of the six dyes used -. 10OxδOcm folded over and interlocked along the open sides to make a 50x50cm "double panel". In addition the load contained seven 50x50cm "double panels" of undyed cotton drill + 14 50x50cm single panels of undyed cotton interlock as 'ballast' making the total load weight up to 2.5kg.

Sodium thiosulphate was added as the pentahydate at a level of 1 % on weight of formulation.

In 'control' no thiosulphate was added. In 'compare' the thiosulphate was added entirely (1.1g) to the main wash. This is comparable to the examples in the prior art.

In 'invention' the thiosulphate addition was split evenly across the main wash and each of the four rinses (0.22g in each stage).

The wash load was dried in a Miele Novotronic T430 tumble dryer (extra dry cycle) after each wash. The loads were washed a total of 10 times.

After 10 wash/dry cycles the dyed cloths were measured and the differences from new were calculated. Measurements were carried out on a Datacolor Spectraflash ™ SF600+, UV excluded (400nm cutt-off), specular included, large apeture (25mm). Changes in colour/lightness were determined using the "CIELAB" system (L = lightness, a = red-green, b = blue-yellow).

Example 2a: Fabric 1 - 5% Vat Blue 4 (95% confidence limits shown in parenthesis).

Example 2b: Fabric 2 - 6% Reactive Black 5

Example 2c: Fabric 3 - 4% Reactive Orange 16

Example 2d: Fabric 4 - 3.85% Reactive Yellow 138:1 + 1.35% Reactive Red 231 + 2.41 % Reactive Blue 198

Example 2e: Fabric 5 - 1.6% Reactive Orange 107 + 1.2% Reactive Red 198 + 1.2% Reactive Blue 220

Example 2f: Fabric 6 - 2.2% Reactive Orange 107 + 1.3% Reactive Red 198 + 1.3% Reactive Black 5

In all cases, adding the thiosulphate reducing agent to the rinse as well as the main wash reduces the level of fading, particularly as regards the lightness (dl_).

Claims

1. A method of conferring a colour benefit or dye benefit to a textile during a laundry process where chemically treated water is utilised, said process comprising at least a wash step and a rinse step, comprising the steps of:

characterised in that:

the further active agent is incorporated in a different and separate rinse- added laundry treatment composition, and, the chemically treated water comprises active chlorine species or ozone.

2. A method according to claim 1 or claim 2, wherein the chlorinated water comprises active chlorine species at a level of from 0.01 to 5ppm.

3. A method according to claim 2, wherein the chlorinated water comprises active chlorine species at a level of from 0.01 to 3ppm.

4. A method according to any one of claims 1 to 3, wherein the active chlorine species are, or are derived from chlorine, chlorine dioxide, or hypochlorite or salts thereof.

5. A method as claimed in any one of claims 1 to 4, wherein the rinse-added laundry treatment composition is contacted with the fabric during the final rinse step.

6. A method as claimed in claim 5, wherein the laundry process comprises a wash step, at least one intermediate rinse step and a final rinse step.

7. A method as claimed in claim 6, wherein the laundry process comprises three intermediate rinse steps.

8. A method as claimed in any one of claims 1 to 7, wherein the reduction potential of the reducing agent is in the range of from -500 to -600 mV in reference to a normal hydrogen electrode.

9. A method claimed in any one of claims 1 to 8, wherein the reducing agent is selected from the group consisting of the alkali and alkaline earth metal salts of thiosulphate, sulphite, bisulphite and metabisulphite anions.

10. A method claimed in claim 9, wherein the reducing agent is sodium thiosulphate.

11. A method as claimed in claim 8 or claim 9, wherein the reducing agent is present in the main wash and at least one rinse stage at a concentration of between at least 0.0001 g/l, preferably between 0.0001 and 5 g/l, more preferably between 0.001 and 2 g/l and most preferably between 0.005 and 2 g/l.

12. A method as claimed in any one of claims 1 to 11 , wherein the further active agent is encapsulated, contained in a dispensing device, immobilised in a carrier or in a slow release formulation.

13. A method as claimed in any one of claims 1 to 12, wherein the further active agent is added by means of automatic dosing by a washing machine.

14. A method as claimed in claim 12, wherein the further active agent is added by means of a dispensing device containing said active agent immobilised in a PEG-based carrier.

15. A method as claimed in claim 12 or 14, wherein the dispensing device is a dual or multi compartment dispensing device comprising the active agent immobilised on a carrier material with one or more separate compartments.