EP2358852B1

EP2358852B1 - Laundry detergent composition

Info

Publication number: EP2358852B1
Application number: EP09768105.0A
Authority: EP
Inventors: Ian Howell; Anthony Mckee
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2008-12-17
Filing date: 2009-12-15
Publication date: 2019-03-27
Anticipated expiration: 2029-12-15
Also published as: AU2009327141B2; PL2358852T3; CN102257109B; BRPI0922587A2; EP2358852A1; TR201906017T4; AU2009327141A1; ES2731593T3; WO2010069957A1; ZA201103716B; BRPI0922587B1; CN102257109A; CA2745559A1

Description

The present invention relates to the use of hydroxamic acid and its corresponding salts in laundry detergent compositions with low levels of zeolite and phosphate builder, leading to improved detergency and stain removal.
Improvement of stain removal is one of the constant goals of the detergents industry, as this may lead to savings on the use of chemicals in detergent compositions, or may lead to washing at lower temperature, and/or for shorter times, and therewith saving energy. Therefore there is still an interest to improve the detergency effect, especially the primary detergency effect of laundry detergent compositions on textile stains, for example particulate stains, such as stains comprising soils or clay, or plant based stains, such as grass. Especially particulate stains are difficult to remove during the laundering process.
Hydroxamic acids are a class of chemical compounds in which a hydroxylamine is inserted into a carboxylic acid. The general structure of a hydroxamic acid is the following:
in which R¹ is an organic residue, for example alkyl or alkylene groups. The hydroxamic acid may be present as its corresponding alkali metal salt, or hydroxamate.
The hydroxamates may conveniently be formed from the corresponding hydroxamic acid by substitution of the acid hydrogen atom by a cation:
L⁺ is a monovalent cation such as for example the alkali metals (e.g. potassium, sodium), or ammonium or a substituted ammonium.
Hydroxamic acids and hydroxamates are known to be useful as metal chelators. They have also been used in detergent compositions in order to improve bleaching performance, as well as use as a builder substance.
EP 388 389 A2 discloses bleach free under built liquid detergent compositions containing hydroxamic acids and their derivatives which assist in the removal of bleachable wine stains from fabrics during laundering. Hydroxamic acids as in formula 1 are disclosed, wherein R¹ represents an optionally substituted straight- or branched chain C₅-C₂₁ alkyl or C₅-C₂₁ alkenyl group or an optionally-substituted phenyl group, and R² represents hydrogen, or an optionally substituted C₁-C₆ alkyl group, or an optionally-substituted phenyl group. One of the examples shows an improved bleaching performance when a hydroxamate is used in a detergent composition in hard water (20° German hardness, which is about 143 milligram calcium per litre). The examples use C₁₂ linear, C₁₂ branched, C₁₃ branched and C₁₈ hydroxamates in detergent formulations comprising mixtures of anionic surfactant and nonionic surfactant. In examples I, II and IV there is an excess of nonionic surfactant of at least 1.25 to 1 and in example III there is 100% anionic surfactant. The liquids also contain at least 6 wt% ethanol, which assists in solubilising the long chain hydroxamates.
EP 384 912 A2 discloses the use of hydroxamic acids and their derivatives as stabilizers for peroxygen bleach compounds in built, mainly granular, detergent compositions. Fully formulated detergent powder examples with 20 wt% zeolite used C₁₂, C₁₃ and C₁₂ branched hydroxamates. C₁₈ was also used.
US 4,874,539 discloses polymeric carboxy hydroxamic acids useful as detergent additives, especially as metal ion chelating agents, and also leading to improved tea stain removal from a test cloth, as compared to a detergent powder without a metal ion chelating agent.
US 4,863,636 discloses liquid detergent compositions comprising one or more detersive surfactants and one or more of N-hydroxyimide or carboxy hydroxamic acid detergent additives. These compounds serve as active metal ion chelants, leading to improved stain removal.
WO 97/48786 discloses a multicomponent system for use with detergent substances, containing an oxidation catalyst, a suitable oxidant, at least one mediator that has been selected from the group of, among others, hydroxamic acids and hydroxamic acid derivatives, a co-mediator, and optionally a low quantity of at least one free amine of each inserted mediator. This system leads to improved bleach function of the detergent, and less consumption of a mediator.
GB 1317445 discloses detergent compositions comprising an alkali-metal salt of a hydroxamic acid. The function of this salt is to prevent the corrosion of copper and copper alloys that is utilised in the construction of the washing machines.
We have now surprisingly found that the primary detergency effect, especially on red clay particulate soil, can be improved by incorporating specific hydroxamic acids and/or hydroxamates in specific laundry detergent compositions.
Laundry detergents need to be able to remove everyday dirt and stains that are commonly found in a wash load. Two particular stains that are problematic, especially when children's wear or sport's wear is being washed, are clay soil stains and grass stains. One type of clay that is particularly resistant to removal by surfactants alone is red clay, such as red pottery clay or Red Georgia clay. This is a particulate soil stain.
Accordingly, the present invention provides a laundry detergent composition according to claim 1.
It should be understood that references to a number of carbon atoms include mixed chain length materials provided that some of the hydroxamate material falls within the ranges specified and the ratios and amounts are determined by excluding any material falling outside of the specified range.
Soap is not included in the calculation of anionic surfactant amounts and ratios.
It is undesirable to have ethanol present at all as it is an explosion hazard during manufacture, and subsequently. Due to the relatively high levels of hydroxamate that are present in the formulation, if a high level of surfactant is present, it is necessary to seek alternative hydrotrope systems. We prefer a hydrotrope system comprising propylene glycol and glycerol at levels of at least 6 wt%, more preferably at least 10 wt%. By using high levels of hydroxamate and surfactant in the composition, it is possible to use less composition per wash, which has consequential benefits for the storage and transportation of the resulting concentrated formulation. Such concentrated formulations comprise at least 20 wt% of the detersive surfactant system, preferably at least 30 wt% and more preferably over 40 wt%.
The preferred hydroxamates are those where R² is Hydrogen and R¹ is C₈ to C₁₄ alkyl, preferably normal alkyl, most preferably saturated.
The detergent composition is preferably used in an aqueous wash liquor, but may comprise one or more solvents suitable for use for domestic laundry purposes. Preferably, the improved stain removal occurs during the main wash of the laundry process, i.e. preferably the laundry detergent composition in which the hydroxamates are used is a main wash product. The wash liquor is preferably free of formate salts. Furthermore, it is preferably free from bleach, especially peroxygen bleach.
The composition may comprise from 1 to 15 wt% soap. The preferred soaps are made from saturated fatty acids.
Especially preferred compositions comprise at least 0.5 wt% of soil release polymer. This improves the multiwash performance of the detergent system for the removal of the clay. Inclusion of at least 0.5 wt% anti redeposition polymer is also beneficial due to the very high efficiency of primary detergency soil removal meaning that there is an increased level of soil in the wash liquor, which must then be prevented from redeposition onto the same or a different piece of fabric.
The preferred ratio of hydroxamate to detersive surfactant system for optimum particulate red clay soil removal lies in the range 1:7 to 1:13. An even more preferred range of ratios being 1:9 to 1:11 parts by weight.
The preferred ratio of anionic to nonionic surfactant for particulate red clay soil removal is at least 1:1, more preferably at least 3:2. Preferably, it is at most 9:1. So a most preferred range is 1:1 to 9:1, or 3:2 to 9:1.
The compositions are particularly suitable for use on particulate stains such as soils and clays, especially red clay, and also surprisingly grass.
The invention also extends to the use of 0.5 to 20 wt% hydroxamic acid or its corresponding hydroxamate of the structure:
wherein R¹ is a C₈ normal alkyl group, and R² is a hydrogen atom, in a laundry detergent composition, for improving the particulate soils stain removal from a textile substrate, wherein the composition further comprises a detersive surfactant system comprising anionic surfactant and nonionic surfactant at a concentration from 3 to 80 wt%; and optionally other ingredients to 100 wt%.
The hydroxamate may be incorporated within the laundry detergent compositions in any suitable fashion within the knowledge of a person of ordinary skill in the art.

Detailed Description of the Invention

Whenever either the term 'hydroxamic acid' or 'hydroxamate' is used in this specification, this encompasses both hydroxamic acid and the corresponding hydroxamate (salt of hydroxamic acid), unless indicated otherwise.
All percentages mentioned herein are by weight calculated on the total composition, unless specified otherwise. The abbreviation 'wt%' is to be understood as % by weight of the total composition.
The stained fabric is treated with the laundry detergent composition comprising hydroxamate according to the invention and the primary detergency is the measured stain removal by the laundry composition on the stain. This is a separate process to so-called soil release using a polymer, which is treatment of fabric with a polymer (through a wash or other such treatment), with subsequent staining of the fabric, the soil release polymer having the effect of the easier removal of the stain.
The following definitions pertain to chemical structures, molecular segments and substituents:
Molecular weights of monomers and polymers are expressed as weight average molecular weights, except where otherwise specified.
The textile/fabric substrates used can be any typical textile/fabric substrate, such as cotton (woven, knitted & denim), polyester (woven, knitted & micro fibre), nylon, silk, polycotton (polyester/cotton blends), polyester elastane, cotton elastane, viscose rayon, acrylic or wool. Particularly suitable textile/fabric substrates are cotton, polycotton and polyester substrates.
Particulate stains are stains comprising for example dirt, soil, clay, mud or soot. They are predominately solid in nature and come into contact with fabrics in the course of their regular use.

Hydroxamic acid and derivatives

The general structure of a hydroxamic acid in the context of the present invention has been indicated in formula 3, and R¹, is as defined above. R¹ is chosen from the group consisting of C₄, C₅, C₆, C₇, C₈, C₉, C₁₀, C₁₁, or C₁₂ or C₁₄ normal alkyl group, most preferably R¹ is at least a C_8-14 normal alkyl group. When the C₈ material is used this is called octyl hydroxamic acid. The potassium salt is particularly useful.
Without wishing to be bound by theory, we believe that the hydroxamate acts by binding to metal ions that are present in the soil on the fabric. This binding action, which is, in effect, the known sequestrant property of the hydroxamate is not, in itself, of any use to remove the soil from the fabric. The key is the "tail" of the hydroxamate i.e. the group R¹ minus any branching that folds back onto the amate Nitrogen via group R². The tail is selected to have an affinity for the surfactant system. This means that the soil removal ability of an already optimised surfactant system is further enhanced by the use of the hydroxamate as it, in effect, labels the difficult to remove particulate material (clay) as "soil" for removal by the surfactant system acting on the hydroxamate molecules now fixed to the particulates via their binding to the metal ions embedded in the clay type particulates. The detersive surfactants will adhere to the hydroxamate, leading overall to more surfactants interacting with the fabric, leading to better soil release. Therewith the hydroxamic acids act as a linker molecule facilitating the removal and suspension of the particulate soil from the fabric into a wash liquor and thus boosting the primary detergency.
This enhancing of the primary detergency of surfactant systems is especially relevant when using concentrated liquid detergent compositions, as the pH during the laundering process is relatively low (pH 7.5-8) as compared to traditional laundering processes with particulate detergent compositions (pH 9-10.5). The lower pH during the laundering process with liquid detergent compositions may lead to reduced soil release, as the surface charges of the soils are less negative as compared to the higher pH during the conventional well built and buffered laundering processes, achieved with conventional zeolite or phosphate built powder products. This surface charge of the soil may lead to increased repellence of the surfactants by the soil, possibly leading to reduced release of the soil. Hence, in a preferred embodiment, the hydroxamates are used in liquid detergent compositions, and more preferred the detersive surfactant concentration in said liquid detergent compositions is from 20 to 80 wt%.
The hydroxamates have a higher affinity for transition metals, like iron, than for alkaline earth metals like calcium and magnesium, therefore the hydroxamic acid primarily acts to improve the removal of soil on fabric, especially particulate soils, and not additionally as a builder for calcium and magnesium. This selectively is especially beneficial if the laundering composition is underbuilt; especially when it comprises less than 5 wt% zeolite or phosphate builder.

Surfactants

The laundry detergent composition in which the hydroxamate is used comprises a detersive surfactant system at a concentration from 3 to 80 wt%. By a detersive surfactant system, we mean that the surfactants therein provide a detersive, i.e. cleaning effect to textile fabrics treated as part of a laundering process. Other surfactants, which are not detersive surfactants, can be used as part of the composition.
Preferably, the detersive surfactant is present at a level of from 5 to 60 wt%, more preferably from 10 to 50 wt%. Even more preferably, the detersive surfactant system comprises at least 20, or 30 or even 40 wt% of the composition.
In general, any surfactant may be used as detersive surfactants, including anionic, nonionic, cationic, and amphoteric or zwitterionic surfactants, or combinations of these, provided that there is anionic and nonionic surfactant present in the range of ratios specified above.
Cationic surfactant may optionally be present as part of the detersive surfactant.
Anionic surfactant is present at a level of from 0.1 to 50 wt%, preferably from 1 to 40 wt%, more preferably from 1.5 to 25 wt%. Nonionic surfactant is incorporated at a level of from 0.1 to 50 wt%, preferably from 1 to 40 wt%, more preferably from 1.5 to 25 wt%. The ratio of anionic surfactant to nonionic surfactant is from 19:1 to 1:1.1, more preferably from 9:1 to 1:1.
In general, the nonionic and anionic surfactants of the surfactant system may be chosen from the surfactants described in 'Surface Active Agents' Vol. 1, by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, in the current edition of 'McCutcheon's Emulsifiers and Detergents' published by Manufacturing Confectioners Company or in Tenside-Taschenbuch', H. Stache, 2nd Edn., Carl Hauser Verlag, 1981.

Nonionic surfactant

For the purposes of this disclosure, 'nonionic surfactant' shall be defined as amphiphilic molecules with a molecular weight of less than about 10,000, unless otherwise noted, which are substantially free of any functional groups that exhibit a net charge at the normal wash pH of 6-11.
Any type of nonionic surfactant may be used, although preferred materials are further discussed below. Highly preferred are fatty acid alkoxylates, especially ethoxylates, having an alkyl chain of from C₈-C₃₅, preferably C₈-C₃₀, more preferably C₁₀-C₂₄, especially C₁₀-C₁₈ carbon atoms, for example, the Neodol range from Shell (The Hague, The Netherlands); ethylene oxide/propylene oxide block polymers which may have molecular weight from 1,000 to 30,000, for example, Pluronic (trademark) from BASF (Ludwigshafen, Germany); and alkylphenol ethoxylates, for example Triton X-100, available from Dow Chemical (Midland, Mich., USA).
Other nonionic surfactants should also be considered within the scope of this invention. These include condensates of alkanolamines with fatty acids, such as cocamide DEA, polyol-fatty acid esters, such as the Span series available from Uniqema (Gouda, The Netherlands), ethoxylated polyol-fatty acid esters, such as the Tween series available from Uniqema (Gouda, The Netherlands), alkylpolyglucosides, such as the APG line available from Cognis (Düsseldorf, Germany) and n-alkylpyrrolidones, such as the Surfadone series of products marketed by ISP (Wayne, N.J., USA). Furthermore, nonionic surfactants not specifically mentioned above, but within the definition, may also be used.
The more preferred nonionic surfactants are the fatty acid ethoxylates with an average degree of ethoxylation of 7, alkoxylates with one propylene oxide and multiple ethylene oxide units, seed oil based surfactant, such as Ecosurf SA7 or SA9 available from Dow Chemical, APGs, and branched alcohol Guerbet nonionics.

Anionic surfactant

'Anionic surfactants' are defined herein as amphiphilic molecules comprising one or more functional groups that exhibit a net anionic charge when in aqueous solution at the normal wash pH of between 6 and 11.
Preferred anionic surfactants are the alkali metal salts of organic sulphur reaction products having in their molecular structure an alkyl radical containing from about 6 to 24 carbon atoms and a radical selected from the group consisting of sulphonic and sulphuric acid ester radicals.
Although any anionic surfactant hereinafter described can be used, such as alkyl ether sulphates, soaps, fatty acid ester sulphonates, alkyl benzene sulphonates, sulphosuccinate esters, primary alkyl sulphates, olefin sulphonates, paraffin sulphonates and organic phosphate; preferred anionic surfactants are the alkali and alkaline earth metal salts of fatty acid carboxylates, fatty alcohol sulphates, preferably primary alkyl sulfates, more preferably they are ethoxylated, for example alkyl ether sulphates; alkylbenzene sulphonates, alkyl ester fatty acid sulphonates, especially methyl ester fatty acid sulphonates and mixtures thereof.

Cationic, amphoteric surfactants and/or zwitterionic surfactants

Also cationic, amphoteric surfactants and/or zwitterionic surfactants may be present in the laundry detergent compositions in which the hydroxamate is used as cosurfactant according to the invention.
Preferred cationic surfactants are quaternary ammonium salts of the general formula R₁R₂R₃R₄N⁺ X^-, for example where R₁ is a C₁₂-C₁₄ alkyl group, R₂ and R₃ are methyl groups, R₄ is a 2-hydroxyethyl group, and X^- is a chloride ion. This material is available commercially as Praepagen (Trade Mark) HY from Clariant GmbH, in the form of a 40% by weight aqueous solution.
In a preferred embodiment the laundry detergent composition in which the hydroxamate is used according to the invention further comprises an amphoteric or zwitterionic surfactant. Amphoteric surfactants are molecules that contain both acidic and basic groups and will exist as zwitterions at the normal wash pH of between 6 and 11. Preferably an amphoteric or zwitterionic surfactant is present at a level of from 0.1 to 20% by weight, more preferably from 0.25 to 15% by weight, even more preferably from 0.5 to 10% by weight.
Suitable zwitterionic surfactants are exemplified as those which can be broadly described as derivatives of aliphatic quaternary ammonium, sulfonium and phosphonium compounds with one long chain group having about 8 to about 18 carbon atoms and at least one water solubilizing radical selected from the group consisting of sulfate, sulfonate, carboxylate, phosphate or phosphonate. A general formula for these compounds is:

R₁(R₂)_xY⁺R₃Z^-

wherein R₁ contains an alkyl, alkenyl or hydroxyalkyl group with 8 to 18 carbon atoms, from 0 to 10 ethylene-oxy groups or from 0 to 2 glyceryl units; Y is a nitrogen, sulphur or phosphorous atom; R₂ is an alkyl or hydroxyalkyl group with 1 to 3 carbon atoms; x is 1 when Y is a sulphur atom and 2 when Y is a nitrogen or phosphorous atom; R₃ is an alkyl or hydroxyalkyl group with 1 to 5 carbon atoms and Z is radical selected from the group consisting of sulfate, sulfonate, carboxylate, phosphate or phosphonate.
Preferred amphoteric surfactants are amine oxides, for example coco dimethyl amine oxide.
Preferred zwitterionic surfactants are betaines, and especially amidobetaines. Preferred betaines are C₈ to C₁₈ alkyl amidoalkyl betaines, for example coco amido betaine. These may be included as co-surfactants, preferably present in an amount of from 0 to 10 wt %, more preferably 1 to 5 wt %, based on the weight of the total composition. Other betaines that may be employed are sulfatobetaines, such as 3-(dodecyldimethylammonium)-1-propane sulfate; and 2-(cocodimethylammonium)-1-ethane sulfate. Sulfobetaines, such as: 3-(dodecyldimethyl-ammonium)-2-hydroxy-1-propane sulfonate; 3-(tetradecyldimethylammonium)-1-propane sulfonate; 3-(C₁₂-C₁₄ alkyl-amidopropyldimethylammonium)-2-hydroxy-1-propane sulfonate; and 3-(cocodimethylammonium)-1-propane sulfonate. Carboxybetaines, such as (dodecyldimethylammonium) acetate (also known as lauryl betaine); (tetradecyldimethylammonium) acetate (also known as myristyl betaine); (cocodimethylammonium) acetate (also known as coconut betaine); (oleyldimethylammonium) acetate (also known as oleyl betaine); (dodecyloxymethyldimethylammonium) acetate; and (cocoamido-propyldimethylammonium) acetate (also known as cocoamido-propyl betaine or CAPB).
The sulfoniumbetaines, such as: (dodecyldimethylsulfonium) acetate; and 3-(cocodimethyl-sulfonium)-1-propane sulfonate.
The phosphoniumbetaines, such as 4-(trimethytphosphonium)-1-hexadecane sulfonate; 3-(dodecyldimethylphosphonium)-1-propanesulfonate; and 2-(dodecyldimethylphosphonium)-1 -ethane sulfate.
The laundry detergent compositions preferably comprise carboxybetaines or sulphobetaines as amphoteric or zwitterionic surfactants, or mixtures thereof. Especially preferred is lauryl betaine. The betaines and hydroxamates may provide even further enhanced particulate soil removal when used together in the compositions according to the invention.

Detergency builders

The laundry detergent compositions in which the hydroxamate is used preferably comprise low levels of detergency builder, based on the weight of the total composition. The amounts of the inorganic builders zeolite and phosphate are less than 5 wt%. These builders are considered to be harmful to the environment when used in large quantities. Furthermore they need to be used at high levels to have a significant building effect and this is inconsistent with the modern concentrated highly weight efficient laundry detergent formulations.
Preferably the builder is selected from the group of alkali and alkaline earth metal carbonates (e.g. sodium carbonate), silicates (e.g. layered silicate), and organic builders such as citrates (e.g. sodium citrate), succinates, sulphamates and malonates, and any combination of these. The organic builders are preferred. They may be used at levels of 1 wt% or more, up to, say, 50 wt%.
Organic builders that may be present include polycarboxylate polymers such as polyacrylates and acrylic/maleic copolymers; polyaspartates; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-di- and trisuccinates, carboxymethyloxysuccinates, carboxy-methyloxymalonates, dipicolinates, hydroxyethyliminodiacetates, alkyl- and alkenylmalonates and succinates; and sulphonated fatty acid salts.
Organic builders may be used in minor amounts Especially preferred organic builders are citrates, suitably used in amounts of from 1 to 30 wt%, preferably from 1.5 to 10 wt%; and acrylic polymers, more especially acrylic/maleic copolymers, suitably used in amounts of from 0.5 to 15 wt%, preferably from 1 to 10 wt%.
Builders, both inorganic and organic, are preferably present in alkali metal salt, especially sodium salt, form.

Other optional Ingredients

In addition to the essential components detailed in the claims, the formulation may include one or more optional ingredients to enhance performance and properties. While it is not necessary for these elements to be present in order to practice this invention, the use of such materials is often very helpful in rendering the formulation acceptable for consumer use.
Examples of optional components include, but are not limited to: hydrotropes, fluorescent whitening agents, photobleaches, fibre lubricants, reducing agents, enzymes, enzyme stabilising agents (such as borates and polyols), powder finishing agents, defoamers, bleaches, bleach catalysts, soil release agents, especially soil release polymers for cotton or polyester or both, antiredeposition agents, especially antiredeposition polymers, dye transfer inhibitors, buffers, colorants, fragrances, pro-fragrances, rheology modifiers, anti-ashing polymers, preservatives, insect repellents, soil repellents, water-resistance agents, suspending agents, aesthetic agents, structuring agents, sanitisers, solvents, including aqueous and non-aqueous solvents, fabric finishing agents, dye fixatives, wrinkle-reducing agents, fabric conditioning agents and deodorizers.
These optional ingredients may include, but are not limited to, any one or more of the following: soap, peroxyacid and persalt bleaches, bleach activators, sequestrants, cellulose ethers and esters, other antiredeposition agents, sodium sulphate, sodium silicate, sodium chloride, calcium chloride, sodium bicarbonate, other inorganic salts, fluorescers, photobleaches, polyvinyl pyrrolidone, other dye transfer inhibiting polymers, foam controllers, foam boosters, acrylic and acrylic/maleic polymers, proteases, lipases, cellulases, amylases, other detergent enzymes, citric acid, soil release polymers, fabric conditioning compounds, coloured speckles, and perfume.
The laundry detergent composition may suitably contain a bleach system based on peroxy bleach compounds, for example, inorganic persalts or organic peroxyacids, capable of yielding hydrogen peroxide in aqueous solution. Suitable peroxy bleach compounds include organic peroxides such as urea peroxide, and inorganic persalts such as the alkali metal perborates, percarbonates, perphosphates, persilicates and persulphates. Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate. Especially preferred is sodium percarbonate having a protective coating against destabilisation by moisture. Sodium percarbonate having a protective coating comprising sodium metaborate and sodium silicate is disclosed in GB 2 123 044B (Kao).
The peroxy bleach compound is suitably present in an amount of from 5 to 35% by weight, preferably from 10 to 25% by weight.
The peroxy bleach compound may be used in conjunction with a bleach activator (bleach precursor) to improve bleaching action at low wash temperatures. The bleach precursor is suitably present in an amount of from 1 to 8% by weight, preferably from 2 to 5% by weight.
Preferred bleach precursors are peroxycarboxylic acid precursors, more especially peracetic acid precursors and peroxybenzoic acid precursors; and peroxycarbonic acid precursors. An especially preferred bleach precursor suitable for use in the present invention is N,N,N',N'-tetracetyl ethylenediamine (TAED). Also of interest are peroxybenzoic acid precursors, in particular, N,N,N-trimethylammonium toluoyloxy benzene sulphonate.
A bleach stabiliser (heavy metal sequestrant) may also be present. Suitable bleach stabilisers include ethylenediamine tetraacetate (EDTA) and the polyphosphonates such as Dequest (Trade Mark), EDTMP.
However, notwithstanding the above it is preferred for the composition to contain no bleach and to rely on the improved clay stain removal derived from the novel hydroxamate and surfactant combination. This is particularly the case for liquid compositions.
The detergent compositions may also contain one or more enzymes. Suitable enzymes include the proteases, amylases, cellulases, oxidases, peroxidases and lipases usable for incorporation in detergent compositions.
In particulate detergent compositions, detergency enzymes are commonly employed in granular form in amounts of from about 0.1 to about 3.0 wt%. However, any suitable physical form of enzyme may be used in any effective amount.
Antiredeposition agents, for example cellulose esters and ethers, for example sodium carboxymethyl cellulose, may also be present.
The compositions may also contain soil release polymers, for example sulphonated and unsulphonated PET/POET polymers, both end-capped and non-end-capped, and polyethylene glycol/polyvinyl alcohol graft copolymers such as Sokolan (Trade Mark) HP22. Especially preferred soil release polymers are the sulphonated non-end-capped polyesters described and claimed in WO 95 32997A (Rhodia Chimie).

Product form and preparation

A product according to the invention may take any suitable form, such as a solid, liquid or paste composition, for example as particulates (powders, granules), tablets or bars.
Preferably, the product is in a concentrated liquid with a surfactant concentration of at least 30wt%. Such compositions require the presence of hydrotropes to solubilise the ingredients. Ethanol is preferably avoided. Preferred hydrotropes are propylene glycol and glycerol. Based on this teaching the skilled person will be able to select other hydrotropes that avoid the use of highly volatile solvents like ethanol without the need for inventive activity.
According to a second embodiment of the invention, the detergent composition is in particulate form. The ratio of anionic to nonionic surfactant in the detersive surfactant system is then preferably at least 3:2, preferably at least 7:2.
Powders of low to moderate bulk density may be prepared by spray-drying slurry, and optionally post dosing (dry-mixing) further ingredients. Routes available for powder manufacture include spray drying, drum drying, fluid bed drying, and scraped film drying devices such as the wiped film evaporator. A preferred form of scraped film device is a wiped film evaporator. One such suitable wiped film evaporator is the 'Dryex system' based on a wiped film evaporator available from Ballestra S.p.A.. Alternative equipment would be the Chemithon the 'Turbo Tube' dryer system wherein a high active surfactant paste is heated and metering to a multi tube, steam-jacketed drying vessel.
'Concentrated' or 'compact' powders may be prepared by mixing and granulating processes, for example, using a high-speed mixer/granulator, or other non-tower processes.
Tablets may be prepared by compacting powders, especially 'concentrated' powders.
The invention will now be further described with reference to the following non-limiting examples.

EXAMPLES

Measurement of Soil Release Index (SRI)

SRI is a measure of how much of a stain on textile is removed during a washing process. The intensity of any stain can be measured by means of a reffectometer in terms of the difference between the stain and a clean cloth giving ΔE* for each stain. It is defined as ΔE* and is calculated as: $Δ E^{*} = \sqrt{{(L_{stain - before}^{*} - L_{clean - cloth}^{*})}^{2} + {(a_{stain - before}^{*} - a_{clean - cloth}^{*})}^{2} + {(b_{stain - before}^{*} - b_{clean - cloth}^{*})}^{2}}$
L*, a*, and b* are the coordinates of the CIE 1976 (L*, a*, b*) colour space, determined using a standard reflectometer. ΔE* can be measured before and after the stain is washed, to give ΔE* _bw (before wash) and ΔE*_aw (after wash). SRI is then defined as: $SRI = 100 - Δ E_{aw}^{*}$
A SRI of 100 means complete removal of a stain.
ΔE after wash is the difference in L a b colour space between the clean (unwashed) fabric and the stain after wash. So a ΔE after wash of zero means a stain that is completely removed. Therefore, a SRI_aw of 100 is a completely removed stain. The clean (or virgin) fabric is an "absolute standard" which is not washed. For each experiment, it refers to an identical piece of fabric to that which the stain is applied. Therefore, its point in L a b colour space stays constant.

Example 1: Preparation of octyl hydroxamate (potassium salt)

The potassium salt of octyl hydroxamate was prepared by the method disclosed by Raghavan and Fuerstenau (Journal of Colloid and Interface Science, 1975, Vol. 50, p. 319-330).

Example 2: Removal of red clay stains on knitted polyester (2:1)

A wash liquor was formulated, containing as surfactants primary alkyl sulfate (PAS, anionic, ex Kao Emal PH10) and alcohol ethoxylate (nonionic C₁₂-7EO, Neodol 25-7 ex Shell), as shown in table 1 at the indicated concentrations. Additionally the wash liquor contained NaCl at a concentration of 5 mM. Water hardness was 6°FH (soft water, about 24 milligram calcium per litre), and water temperature was 30°C. No builder or sequestrants were added to the composition, as these ingredients were not required due to the soft water used.

Table 1 Concentrations of surfactants and hydroxamate in wash liquors.

Ingredient	Formulation 1	Formulation 2
Ingredient	concentration in wash liquor (g/L)
primary alcohol sulfate	0.33	0.33
alcohol ethoxylate (C₁₂ 7EO)	0.16	0.16
octyl hydroxamate (potassium salt) prepared in example 1	0.00	0.05

The following results were obtained for the removal of red clay stains from knitted polyester cloth, as measured in the following standard protocol, called the soft water Tergotometer wash protocol, using a Tergotometer washing machine. The red clay used is a form of pottery clay.
Soft water Tergotometer wash protocol:

1. Measurement of the colour of the stain on the textile cloth
2. Set Tergotometer to 25°C.
3. Add water and formulation stock solutions to each pot, agitate for 1 minute.
4. Add stain cloths and ballast, switch on Tergotometer.
5. Leave to wash for 12 minutes
6. Rinse cloths in 6° French hard water for 1 minute, repeat rinse.
7. Dry cloths overnight.
8. Measurement of the colour of the stain on the textile cloth

Table 2 Stain removal index (SRI) for red clay stains on knitted polyester

Formulation	SRI
	red clay stains on knitted polyester
1 (comparative)	88.0
2	97.2

This experiment shows that the formulation comprising octyl hydroxamate leads to substantially better removal of red clay stains from knitted polyester in soft water. As this is an experiment in soft water, the mechanism by which the hydroxamic acid acts is not as a builder, therefore the builder effect is excluded as a mechanism of action for improvement of the detergency effect.

Example 3: Removal of Georgia clay stains from knitted polyester and grass stains from woven cotton

Two liquid detergents were formulated. The surfactants used were sodium alkyl benzene sulphonate (Na LAS, anionic), alcohol ethoxylate (nonionic C₁₂-7EO, Neodol 25-7 ex Shell) and a neutralised saturated soap (coco fatty acid (Prifac 5908 ex Uniqema)) as shown in table 3 at the indicated concentrations. Also used were standard compounds of a laundry liquid detergent (builder (sodium citrate), hydrotrope (5% glycerol and 9% propylene glycol), buffer and sequestrant (Dequest 2066 phosphonate), enzyme (Savinase Ultra 16L protease). Two wash liquors were prepared using formulations 3 and 4, respectively, as outlined in table 3, to give surfactant and hydroxamate levels as shown in table 4. The water hardness in the liquors was 26°FH (median water, about 104 milligram calcium per litre), and water temperature was 40°C. The pH was buffered to between 7 and 8.

Table 3 Formulations used

Ingredient	Formulation 3	Formulation 4
Ingredient	% in Product
Na LAS	27.6	27.6
alcohol ethoxylate (C₁₂ 7EO)	12.5	12.5
Na soap	8	8
octyl hydroxamate (potassium salt) prepared in example 1		4
Dequest 2066	0.5	0.5
sodium citrate	2	2
triethanol amine	3.2	3.2
hydrotropes, enzymes & minors	14	14
water	32.2

Table 4 Concentrations of surfactants and hydroxamates in wash liquors based on the formulations in table 3.

Ingredient	Formulation 3	Formulation 4
Ingredient	in wash level (g/L)
Na LAS	0.72	0.72
alcohol ethoxylate (C₁₂ 7EO)	0.33	0.33
Na soap	0.24	0.24
octyl hydroxamate (potassium salt) prepared in example 1	0.00	0.12

The following results were obtained for the removal of Georgia clay stains from knitted polyester cloth and the removal of grass stains from woven cotton, as measured in the following standard protocol, called the Linitest™ wash protocol, using a Linitest™ washing machine.
Linitest™ wash protocol

1. Read before wash stains.
2. Switch on Linitester™ and leave to heat to 40°C.
3. Dose product into pots, add water to pots.
4. Place stains, ballast and 50 ball bearings in pots.
5. Start Linitester™ and leave to wash for 30 minutes.
6. Rinse ballast and cloths for 5 minutes.
7. Repeat rinse.
8. Dry stains overnight.
9. Read after wash stains.

Table 5 Stain removal index (SRI) for Georgia clay stains on knitted polyester and woven cotton and grass on knitted polyester

Formulation	SRI	SRI	SRI
	Georgia clay on knitted polyester	Grass on knitted polyester	Georgia clay on woven cotton
3 (comparative)	79.4	90.1	66.4
4	89.1	92.1	70.7

This experiment shows that the use of the hydroxamate acid leads to better removal of Georgia clay as well as grass on knitted polyester and improved removal of Georgia clay from woven cotton.
Although Savinase is present in the detergent composition, which improves grass stain removal, grass stain removal is further improved by the addition of the hydroxamate.

Example 4. Typical examples of detergent compositions

Some typical detergent compositions according to the present invention are given in table 6.

Table 6 Typical detergent compositions according to the invention.

Ingredient	Powder Formulation (concentration in final product [weight %])	Liquid Detergent Formulation (concentration in final product [weight %])	Concentrated Liquid Detergent (concentration in final product [weight %])
linear alkyl benzene sulphonate	15	16	24
alcohol ethoxylate	5	8	12
Sodium sulphate	40
Sodium carbonate	20
enzymes	1	1	2
whitening agent	0.1	0.1	0.1
hydroxamate	1	2	3
sodium citrate		5	5
sodium chloride		2	2
sodium hydroxide		1	1
dispersant		1	2
perfume, foam control & other minors	balance	balance	balance

Example 5 Hydroxamates with various alky chain lengths

The following results were obtained for the removal of Georgia Clay stains from woven cotton cloth, as measured in the following standard protocol, called the Tergotometer hard water wash protocol, using a Tergotometer washing machine. Different hydroxamates were used according to table 7.

Tergotometer hard water wash protocol:

Measurement of the colour of the stain on the textile cloth
Set Tergotometer to 30°C.
Add water and formulation stock solutions to each pot, agitate for 1 minute.
Add stain cloths and ballast, switch on Tergotometer.
Leave to wash for 12 minutes
Rinse cloths in 26° French hard water for 1 minute, repeat rinse.
Dry cloths overnight.
Measurement of the colour of the stain on the textile cloth

Table 7

Ingredient	Formulation 5	Formulation 6	Formulation 7	Formulation 8	Formulation 9
	wt% in Product
Na LAS	14.3	14.3	14.3	14.3	14.3
alcohol ethoxylate (C₁₂ 7EO)	20.11	20.11	20.11	20.11	20.1 1
Na soap	8.02	8.02	8.02	8.02	8.02
SLES	6.7	6.7	6.7	6.7	6.7
Sodium Citrate	1	1	1	1	1
Triethanolamine	3.2	3.2	3.2	3.2	3.2
Sequestrant (Dequest 2066)	0.5	0.5	0.5	0.5	0.5
Hydrotropes, enzymes and minors	14	14	14	14	14
Hexyl Hydroxamate		5
Octyl Hydroxamate			5
Decyl hydroxamate				5
Dodecyl hydroxamate					5
Water	Balance	Balance	Balance	Balance	Balance

Table 8

Formulation	Dose of Formulation in wash (g/L)	SRl_aw Georgia Clay from Woven Cotton
5 (control)	1.42	69.4
6 (hexyl hydroxamate, potassium salt)	1.42	71.0
7 (Octyl hydroxamate, potassium salt)	1.42	72.7

Table 9

Formulation	Dose of Formulation in wash (g/L)	SRlaw Georgia Clay from knitted polyester
5 (control)	2.72	71.4
7 (Octyl hydroxamate, potassium salt	2.72	72.7
8 (Decyl Hydroxamate, potassium salt)	2.72	81.9
9 (Dodecyl Hydroxamate, potassium salt)	2.72	79.5

Tables 8 and 9 summarise the results on the different cloths.

Example 6: Effect of Anionic Nonionic ratio

Table 10 Formulations A to F (Comparative - without Octyl Hydroxamate)

Ingredient	A	B	C	D	E	F
Ingredient	In Wash Level (g/L)
NaLAS	1	0.8	0.67	0.5	0.25	0
Neodol 25-7 (nonionic surfactant Ex Shell)	0	0.2	0.33	0.5	0.75	1
Sodium salt of Prifac 5908	0.2	0.2	0.2	0.2	0.2

Table 11 Formulations with Octyl hydroxamate

Ingredient	A_OH	B_OH	C_OH	D_OH	E_OH	F_OH
Ingredient	In Wash Level (g/L)
Na LAS (anionic surfactant)	1	0.8	0.67	0.5	0.25	0
Neodol 25-7 (nonionic surfactant) (ex Shell)	0	0.2	0.33	0.5	0.75	1
Octyl Hydroxamate	0.12	0.12	0.12	0.12	0.12	0.12
Sodium salt of Prifac 5908 (soap)	0.2	0.2	0.2	0.2	0.2

This example shows the effect of varying the ration of anionic to nonionic surfactant for the removal of Georgia Clay stains from knitted polyester, as measured in the Tergotometer hard wash protocol described above. The formulations are given in table 11 and the comparative formulations without the hydroxamate are given in table 10.

The results are summarised in table 12. Formulations A-OH, E-OH and F-OH are comparative.

Table 12

Formulation	Anionic:nonionic	SRI_aw (no hydroxamate)	SRI_aw (with hydroxamate)	% increase SRI
A / A_OH	1 to 0	67.3	68.4	1.63
B / B_OH	4 to 1	73.8	80.2	8.67
C / C_OH	2 to 1	73.8	80.4	8.94
D / D_OH	1 to 1	68.9	78.0	13.21
E / E_OH	1 to 3	66.3	69.7	5.13
F / F_OH	0 to 1	66.6	66.2	-0.60

Example 7 - Higher Anionic to Nonionic ratios (Georgia Clay removal from woven cotton)

A number of Anionic/Nonionic formulations were made where the anionic to nonionic surfactant ratio was at least 4:1. A set of comparative formulations without hydroxamate was first made up as per table 13. Then a set of corresponding formulations comprising 5 wt% of octyl hydroxamate was made up as per table 14.

Table 13 (Comparative formulations)

Ingredient	G	H	I	J
Ingredient	wt% in formulation
Na LAS	32.9	37.0	39.0	41.1
alcohol ethoxylate (C₁₂ 7EO)	8.2	4.1	2.1	0
Na soap	8.02	8.02	8.02	8.02
Sodium Citrate	1	1	1	1
Triethanolamine	3.2	3.2	3.2	3.2
Sequestrant (Dequest 2066)	0.5	0.5	0.5	0.5
Hydrotropes, enzymes and minors	14	14	14	14
Water	Balance	Balance	Balance	Balance

The soap used was Prifac 5908. The hydrotropes were glycerol and propylene glycol.

Table 14

Ingredient	G_OH	H_OH	I_OH	J_OH
Ingredient	wt% in formulation
Na LAS	32.9	37.0	39.0	41.1
alcohol ethoxylate (C₁₂ 7EO)	8.2	4.1	2.1	0
Na soap	8.02	8.02	8.02	8.02
Sodium Citrate	1	1	1	1
Triethanolamine	3.2	3.2	3.2	3.2
Sequestrant (Dequest 2066)	0.5	0.5	0.5	0.5
Octyl hydroxamate (potassium salt)	5	5	5	5
Hydrotropes, enzymes and minors	14	14	14	14
Water	Balance	Balance	Balance	Balance

The following results were obtained for the removal of Georgia Clay stains from woven cotton, as measured using the standard hard water Tergotometer wash protocol described above and with an In wash formulation concentration of 2.6 g/L for each of the formulations in tables 13 and 14. The results are given in table 15. Example J-OH is comparative.

Table 15

Formulations	Anionic:nonionic	SRI_aw (no hydroxamate)	SRI_aw (with hydroxamate)	% increase SRI
G / G_OH	4 to 1	67	72.9	8.81
H / H_OH	9 to 1	68.2	70.6	3.52
I / I_OH	19 to 1	67.2	68.6	2.08
J / J_OH	1 to 0	68.8	68.6	-0.29

Example 8: Alternative Anionic: Primary Alkyl sulphate

Table 16 (comparative formulations)

Ingredient	K	L	M	N	O	P
Primary Alkyl Sulphate	0	27.5	32.9	41.1	20.55	10.3
Alcohol ethoxylate (C₁₂ 7EO)	41.1	13.6	8.2	0	20.55	30.8
Na soap	8.02	8.02	8.02	8.02	8.02	8.02
Sodium Citrate	1	1	1	1	1	1
Triethanolamine	3.2	3.2	3.2	3.2	3.2	3.2
Sequestrant (Dequest 2066)	0.5	0.5	0.5	0.5	0.5	0.5
Hydrotropes, enzymes and minors	14	14	14	14	14	14
Water	Balance	Balance	Balance	Balance	Balance	Balance

Table 17 (formulations with hydroxamate)

Ingredient	K_OH	L_OH	M_OH	N_OH	O_OH	P_OH
Primary Alkyl Sulphate	0	27.5	32.9	41.1	20.55	10.3
Alcohol ethoxylate (C₁₂ 7EO)	41.1	13.6	8.2	0	20.55	30.8
Na soap	8.02	8.02	8.02	8.02	8.02	8.02
Sodium Citrate	1	1	1	1	1	1
Triethanolamine	3.2	3.2	3.2	3.2	3.2	3.2
Sequestrant (Dequest 2066)	0.5	0.5	0.5	0.5	0.5	0.5
Octyl hydroxamate (potassium salt)	5	5	5	5	5	5
Hydrotropes, enzymes and minors	14	14	14	14	14	14
Water	Balance	Balance	Balance	Balance	Balance	Balance

The following results in table 18 were obtained for the removal of Georgia Clay stains from knitted polyester, as measured using the hard water Tergotometer wash protocol using 2.6 g/L formulation in wash. The comparative formulations without hydroxamate are given in table 16 and the hydroxamate containing formulations are given in table 17. The hydrotrope system, as usual, comprised 5 wt% glycerol and 9 wt% propylene glycol. Compositions N-OH and P-OH are comparative as the ratio of anionic to nonionic is outside of the claimed range.

Table 18

Formulation	Anionic:nonionic	SRI_aw (no hydroxamate)	SRI_aw (with hydroxamate)	% increase SRI
K / K_OH	0 to 1	73.6	75.4	2.45
P / P_OH	1 to 3	74.0	73.4	-0.81
O / O_OH	1 to 1	74.1	75.6	2.02
L / L_OH	2 to 1	73.4	77.2	5.18
M / M_OH	4 to 1	73.9	77.7	5.14
N / N_OH	1 to 0	73	74.7	2.33

Claims

A laundry detergent composition comprising
a) 0.5 to 20, preferably 6, wt% hydroxamic acid or its corresponding hydroxamate of the structure:

wherein R¹ is chosen from the group consisting of C₄, C₅, C₆, C₇, C₈, C₉, C₁₀, C₁₁, C₁₂ or C₁₄ alkyl group

and R² is hydrogen,

b) 3 to 80 wt% of detersive surfactant system comprising
(i) anionic surfactant; and

(ii) nonionic surfactant
wherein the weight ratio of (i) to (ii) lies in the range 1:1.1 to 19:1, and the weight ratio a) to b) lies in the range 1:5 to 1:15

c) optionally, other ingredients to 100 wt% provided that zeolite and phosphate builders are present at less than 5 wt% and ethanol is present at a level of less than 5 wt%, whereby soap is not included in the calculation of anionic surfactant amounts and ratios.
Composition according to claim 1, wherein R¹ is a C_8-14 normal alkyl group.
A composition according to any of claims 1 to 2, wherein the composition comprises detergency builder at a concentration from 1 to 50 wt%.
A composition according to any preceding claim which comprises at least 20 wt% of the detersive surfactant system, preferably at least 30 wt% and more preferably over 40 wt%.
A composition according to any preceding claim which comprises from 1 to 15 wt% soap, preferably made from saturated fatty acids.
A composition according to any preceding claim comprising at least 0.5 wt% of soil release polymer.
A composition according to any preceding claim comprising at least 0.5 wt% anti redeposition polymer.
A composition according to any preceding claim wherein the ratio of hydroxamate to detersive surfactant system lies in the range 1:7 to 1:13, preferably 1:9 to 1:11 parts by weight.
A composition according to any preceding claim in which the ratio of anionic to nonionic surfactant is at least 1:1, preferably at least 3:2.
A composition according to claim 9 in which the ratio of anionic to nonionic surfactant is 1:1 to 9:1, preferably 3:2 to 9:1.
A composition according to any preceding claim in which the composition is a liquid composition.
A composition according to claim 11 comprising a hydrotrope system comprising propylene glycol and glycerol at levels of at least 6 wt%.
A composition according to claim 11 or 12, which is a liquid composition, comprising detersive surfactant at a concentration from 20 to 80% by weight of the total composition.