FIELD OF THE INVENTION

This invention relates to a laundry composition. More particularly, the invention is directed to a softening in the wash laundry composition.

BACKGROUND OF THE INVENTION

Textile fabrics, including clothes, have traditionally been cleaned with laundry detergents. After cleaning, fabrics can often feel harsh and they will wear and lose colour over repeat wash cycles. To prevent the drawbacks of fabrics feeling harsh after cleaning and those experienced by multiple wash cycles, technologies have been developed to increase the softness of fabrics, including rinse-added conditioner compositions and softening systems added to the detergent composition.

One such softening system comprises a cationic polysaccharide and anionic surfactant. Such systems are known from WO 2004/069979 which discloses particular combinations of cationic polymers and anionic surfactants.

WO 2008/022838 discloses liquid laundry compositions comprising anionic surfactant, nonionic surfactant, fatty acid and cationic polymers. The compositions are stated to provide both effective softening and cleaning.

There still remains a need for softening laundry detergent compositions that provide improved softening. SUMMARY OF THE INVENTION

In a first aspect, this invention is directed to a liquid detergent composition comprising:-

(a) from 6 to 40 wt.% nonionic surfactant;

(b) from 6 to 20 wt.% anionic surfactant;

(c) from 2 to 14 wt.% fatty acid or salt thereof;

(d) from 0.2 to 1.5 wt.% cationic polysaccharide-based polymer; and, wherein,

the weight ratio of (a) to (b) is from 1.25:1 to 2.25:1 , and wherein the total level of surfactant present in the composition is at least 25 wt.%.

In a second aspect, this invention is directed to a method for the provision of softness to a textile, comprising the steps:

(a) provision of a liquid detergent composition as defined in the first aspect of the invention; and, (b) contacting one or more textile articles with the composition at one or more points during the main wash of a laundering process; and, (c) allowing the textile articles to dry or mechanically tumble-drying them.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "comprising" means including, made up of, composed of, consisting and/or consisting essentially of.

All percentages quoted are wt.% unless otherwise stated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts or ratios of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about".

As used herein, a formula shall be considered physically "stable" when after 1 week at 21 degrees Celsius it exhibits no signs of phase separation.

The present invention is directed to laundry compositions containing fatty acid or salt thereof, a polysaccharide-based cationic polymer, a non-ionic surfactant and an anionic surfactant, wherein the ratio of nonionic to anionic surfactant is from 1.25:1 to 2.25:1 , and wherein the total level of surfactant is at least 25 wt.%. The composition delivers a high level of softening to fabrics in comparison to the prior art. The composition also displays excellent stability.

Softening Benefits

The primary conditioning benefit afforded by these products is softening. Softening includes, but is not limited to, an improvement in the handling of a garment treated with the compositions of this invention relative to that of an article laundered under identical conditions but without the use of this invention. Consumers will often describe an article that is softened as "silky" or "fluffy", and generally prefer the feel of treated garments to those that are unsoftened.

The conditioning benefits of these compositions are not limited to just softening, however. They may, depending on the particular embodiment of the invention selected, also provide an antistatic benefit. In addition to softening, the cationic polymer/an ionic surfactant compositions of this invention are further believed to lubricate the fibres of textile articles, which can reduce wear, pilling and colour fading, and provide a shape-retention benefit. This lubricating layer is also - A -

believed to provide a substrate on the fabric for retaining fragrances and other benefit agents.

Form of the Invention

The present invention can take any of a number of forms that are included as main wash products. It can take the form of a laundry treatment agent for the main wash, which may be dilutable or non-dilutable. The laundry treatment agent may for example be an isotropic liquid, or a surfactant-structured liquid. Particularly preferred forms of this invention include combination detergent/ softener products to provide "softening in the wash".

Softening in the Wash

By the term "softening in the wash" is meant a composition which provides a fabric softening benefit as well as providing cleaning to the laundered fabric. Such a composition can be added as part of a main wash product, or as a separate product for use in combination with another. However, for the purposes of this disclosure, the composition is intended for use in the main wash cycle. Preferably the softening in the wash composition of the invention is incorporated as part of a single product for use in the main wash.

The pH range of the composition is 7-12, preferably 8.5 to 9.5. It is desirable to buffer the formulation at whatever the target pH of the composition is.

Method of Use

The liquid detergent composition provides a softness benefit to the laundered fabrics by a method comprising the steps: (a) provision of a liquid detergent composition as defined in the first aspect of the invention; and,

(b) contacting one or more textile articles with the composition at one or more points during the main wash of a laundering process; and, (c) allowing the textile articles to dry or mechanically tumble-drying them.

Fatty Acid or Salt thereof

The liquid detergent compositions include fatty acid or salt thereof, a term used herein interchangeably with the term 'soap'. Both terms are herein defined as an alkali or alkaline earth metal salt of a natural or synthetic fatty acid containing between 6 and 30 carbon atoms. Preferably the soap contains between C8-C26, more preferably Cs-C2 ₄ , still more preferably Cs-Cis carbon atoms. The incorporation level of the soap is from 2 to 14%, preferably from 2.5 to 10%, more preferably from 3 to 9% by weight of the total composition. Particularly preferred forms of soap are outlined below.

Carboxylic Acid Salts

R ¹ COOM where R ¹ is a primary or secondary alkyl group of 5 to 29 carbon atoms and M is a solubilising cation. The alkyl group represented by R ¹ may represent a mixture of chain lengths and may be saturated or unsaturated, although it is preferred that at least two thirds of the R ¹ groups have a chain length of between 7 and 17 carbon atoms. Non-limiting examples of suitable alkyl group sources include the fatty acids derived from coconut oil, tallow, tall oil and palm kernel oil. For the purposes of minimising odour, however, it is often desirable to use primarily saturated carboxylic acids. Such materials are well known to those skilled in the art, and are available from many commercial sources, such as Uniqema (Wilmington, Del.) and Twin Rivers Technologies (Quincy, Mass.). The solubilising cation, M, is an alkali or alkaline earth metal cation. Preferred examples of cations include alkali metals such as sodium and potassium. Although, when used, the majority of the fatty acid should be incorporated into the formulation in neutralised salt form, it is often preferable to leave a small amount of free fatty acid in the formulation, as this can aid in the maintenance of product viscosity.

Surfactants

The liquid detergent composition comprises nonionic surfactant, and anionic surfactant other than soap. For the avoidance of doubt, the soap present in the composition is not included in the calculation of anionic surfactant for weight inclusion or weight ratios present in the composition. Thus the wt.% of soap present is not included the total amount of surfactant present.

They may be chosen from the surfactants described in "Surface Active Agents" Vol. 1 , by Schwartz & Perry, lnterscience 1949, Vol. 2 by Schwartz, Perry & Berch, lnterscience 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. Preferably the surfactants used are saturated.

Suitable nonionic detergent compounds which may be used include, in particular, the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionic detergent compounds are Cβ to C22 alkyl phenol- ethylene oxide condensates, generally 5 to 25 EO, i.e. 5 to 25 units of ethylene oxide per molecule, and the condensation products of aliphatic Cs to C18 primary or secondary linear or branched alcohols with ethylene oxide, generally 5 to 40 EO. Suitable anionic detergent compounds which may be used are usually water- soluble alkali metal salts of organic sulphates and sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates, especially those obtained by sulphating higher C ₈ to Ci ₈ alcohols, produced for example from tallow or coconut oil, sodium and potassium alkyl Cg to C ₂ O benzene sulphonates, particularly sodium linear secondary alkyl Cio to Ci ₅ benzene sulphonates; and sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum. The preferred anionic detergent compounds are sodium Cu to Ci ₅ alkyl benzene sulphonates and sodium C12 to Ci ₈ alkyl sulphates. Salts of sulphonates included as hydrotrobes can additionally be considered as anionic surfactants as defined herein. Also applicable are surfactants such as those described in EP-A-328 177 (Unilever), which show resistance to salting-out, the alkyl polyglycoside surfactants described in EP-A-070 074, and alkyl monoglycosides.

The nonionic detergent is present in amounts of from 6 to 40 wt.%, preferably from 7.5 to 35 wt.%, more preferably from 10 to 25 wt.%.

The anionic surfactant is present in amounts of from 6 to 20 wt.%, preferably from 6.5 to 17.5 wt.%, more preferably from 7.5 to 15 wt.%.

The ratio of nonionic surfactant to anionic surfactant present in the liquid composition is from 1.25:1 to 2.25:1 , based on weight.

The total amount of surfactant present in the liquid composition is at least 25 wt.%. Preferably the total amount of surfactant is from 25 to 65 wt.%, preferably from 25.5 to 50 wt.%. Other surfactants such as amphoteric, zwitterionic and cationic surfactants may also be present in addition to the aforementioned nonionic and anionic surfactants.

Cationic Polysacchahde-based Polymer

The term "cationic polysaccharide-based polymer" refers to polymers having a polysaccharide backbone and an overall positive charge. Polysaccharides are polymers made up from monosaccharide monomers joined together by glycosidic bonds.

The cationic polysaccharide-based polymers present in the compositions of the invention have a modified polysaccharide backbone, modified in that additional chemical groups have been reacted with some of the free hydroxyl groups of the polysaccharide backbone to give an overall positive charge to the modified cellulosic monomer unit.

A preferred class of cationic polysaccharide polymers suitable for this invention are those that have a polysaccharide backbone modified to incorporate a quaternary ammonium salt. Preferably the quaternary ammonium salt is linked to the polysaccharide backbone by a hydroxyethyl or hydroxypropyl group. Preferably the charged nitrogen of the quaternary ammonium salt has one or more alkyl group substituents.

Preferred cationic polysaccharide-based polymers have a guar based, or cellulosic based backbone. Cellulose based cationic polymers are most preferred.

Guar is a galactomannan having a β-1 ,4 linked mannose backbone with branchpoints to α-1 ,6 linked galactose units. An example of a guar based cationic polymer is guar 2-hydroxy-3-(trimethylammonium) propyl ether salt. Cellulose is a polysaccharide with glucose as its monomer, specifically it is a straight chain polymer of D-glucopyranose units linked via β-1 ,4 glycosidic bonds and is a linear, non-branched polymer. Typical examples of preferred cationic cellulosic polymers include cocodimethylammonium hydroxypropyl oxyethyl cellulose, lauryldimethylammonium hydroxypropyl oxyethyl cellulose, stearyldimethylammonium hydroxypropyl oxyethyl cellulose, and stearyldimethylammonium hydroxyethyl cellulose; cellulose 2-hydroxyethyl 2- hydroxy 3-(thmethyl ammonio) propyl ether salt, polyquaternium-4, polyquaternium-10, polyquaternium-24 and polyquaternium-67 or mixtures thereof.

More preferably the cationic cellulosic polymer is polyquaternium-10. Suitable commercial cationic cellulosic polymer products for use according to the present invention are marketed by the Amerchol Corporation, a subsidiary of The Dow Chemical Company, under the trade name UCARE Polymer LR-400.

The term cationic cellulosic polymer can include a single polymer or a mixture of different polymers.

The countehon of the cationic polymer is freely chosen from the halides: chloride, bromide, and iodide; or from hydroxide, phosphate, sulphate, hydrosulphate, ethyl sulphate, methyl sulphate, formate, and acetate.

Without wishing to be bound by theory, it is believed that the species responsible for providing a softening benefit in these formulations is a polymer/surfactant complex, especially a cationic polymer/soap complex.

The cationic polysacchahde-based polymer is present at a level of from 0.2 to 1.5 wt.%, preferably from 0.25 to 1 wt.%. Many of the aforementioned cationic polymers can be synthesised in, and are commercially available in, a number of different molecular weights. Preferably the molecular weight of the cationic polysacchahde-based polymer is from 10,000 to 850,000 Daltons, more preferably from 10,000 to 500,000 Daltons.

Optional Ingredients

The liquid detergent composition may additionally comprise one or more of the following optional ingredients.

Builders or Complexing Agents

The composition optionally comprises from 1 to 50 wt.% of a builder. Preferably the builder is present at a level of from 1 to 40 wt.%.

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

It is preferred that when an insoluble inorganic builder, e.g., zeolite is used, the size is in the range 0.1 to 10 microns (as measured by The Mastersizer 2000 particle size analyzer using laser diffraction ex Malvern™).

Examples of calcium sequestrant builder materials include alkali metal polyphosphates, such as sodium tripolyphosphate 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 0-50 wt.% of a builder or complexing agent such as ethylenediaminetetraacetic acid, diethylenetriamine-pentaacetic acid, alkyl- or alkenylsuccinic acid, nithlotriacetic acid or the other builders mentioned below. Many builders are also bleach-stabilising agents by virtue of their ability to complex metal ions.

Zeolite and carbonate (carbonate (including bicarbonate and sesquicarbonate) are preferred builders.

The composition may contain as builder a crystalline aluminosilicate, preferably an alkali metal aluminosilicate, 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 M ₂ O. AI ₂ O ₃ . 0.8-6 SiO ₂

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 SiO ₂ 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).

Preferably the laundry detergent formulation is a non-phosphate built laundry detergent formulation, i.e., contains less than 1 wt.% of phosphate.

Shading Agent

The laundry treatment composition preferably comprises a blue or violet shading agent in the range from 0.0001 to 0.01 wt.%. The shading agents reduce the perception of damage to many coloured garments and increase whiteness of white garments.

The shading agents are preferably selected from blue and violet dyes of the solvent disperse basic, direct and acid type listed in the colour index (Society of Dyers and Colouhsts and American Association of Textile Chemists and Colorists 2002).

Preferably a direct violet or direct blue dyes is present. Preferably the dyes are bis-azo, tris-azo dyes or thphendioxazine dye. The carcinogenic benzidene based dyes are not preferred.

Fluorescent Agent

The composition preferably comprises a fluorescent agent (optical bhghtener). Fluorescent agents are well known and many such fluorescent agents are available commercially. Usually, these fluorescent agents are supplied and used in the form of their alkali metal salts, for example, the sodium salts. The total amount of the fluorescent agent or agents used in the composition is generally from 0.005 to 2 wt.%, more preferably 0.01 to 0.1 wt.%. Preferred classes of fluorescer are: Di-styryl biphenyl compounds, e.g. Tinopal (Trade Mark) CBS-X, Di-amine stilbene di-sulphonic acid compounds, e.g. Tinopal DMS pure Xtra and Blankophor (Trade Mark) HRH, and Pyrazoline compounds, e.g. Blankophor SN. Preferred fluorescers are: sodium 2-(4-styryl-3-sulfophenyl)-2H-napthol[1 ,2- d]trazole, disodium 4,4'-bis{[(4-anilino-6-(N methyl-N-2 hydroxyethyl) amino 1 ,3,5- thazin-2-yl)]amino}stilbene-2-2' disulfonate, disodium 4,4'-bis{[(4-anilino-6- morpholino-1 ,3,5-thazin-2-yl)]amino} stilbene-2-2' disulfonate, and disodium 4,4'- bis(2-sulfoslyryl)biphenyl.

Perfume

Preferably the composition comprises a perfume. The perfume is preferably in the range from 0.001 to 3 wt.%, most preferably 0.1 to 1 wt.%. Many suitable examples of perfumes are provided in the CTFA (Cosmetic, Toiletry and Fragrance Association) 1992 International Buyers Guide, published by CFTA Publications and OPD 1993 Chemicals Buyers Directory 80th Annual Edition, published by Schnell Publishing Co.

It is commonplace for a plurality of perfume components to be present in a formulation. In the compositions of the present invention it is envisaged that there will be four or more, preferably five or more, more preferably six or more or even seven or more different perfume components.

In perfume mixtures preferably 15 to 25 wt.% are top notes. Top notes are defined by Poucher (Journal of the Society of Cosmetic Chemists 6(2):80 [1955]). Preferred top-notes are selected from citrus oils, linalool, linalyl acetate, lavender, dihydromyrcenol, rose oxide and cis-3-hexanol. Perfume and top note may be used to cue the fabric care benefit of the invention.

It is preferred that the laundry treatment composition does not contain a peroxygen bleach, e.g., sodium percarbonate, sodium perborate, and peracid.

Polymers

The composition may comprise one or more polymers. Examples are carboxymethylcellulose, poly(ethylene glycol), polyvinyl alcohol), polycarboxylates such as polyacrylates, maleic/acrylic acid copolymers and lauryl methacrylate/acrylic acid copolymers.

Hvdrotrobe

The liquid detergent composition may optionally include a hydrotrope, which can prevent liquid crystal formation. The addition of the hydrotrope thus aids the clarity/transparency of the composition. Suitable hydrotropes include but are not limited to propylene glycol, ethanol, urea, salts of benzene sulphonate, toluene sulphonate, xylene sulphonate or cumene sulphonate. Suitable salts include but are not limited to sodium, potassium, ammonium, monoethanolamine, triethanolamine. Salts of sulphonates can also be considered as anionic surfactants as defined herein. Preferably, the hydrotrope is selected from the group consisting of propylene glycol, xylene sulfonate, ethanol, and urea to provide optimum performance. The amount of the hydrotrope is generally in the range of from 0 to 30%, preferably from 0.5 to 30%, more preferably from 0.5 to 30%, most preferably from 1 to 15%. Examples

Method of Production

Water, fluorescer and hydrotropes are mixed together at ambient temperature (approximately 22 ⁰ C) for 2-3 minutes at a shear rate of 130 rpm using a Janke & Kunkel IKA RW20 overhead mixer. Salts and alkalis are added and mixed for 5 minutes prior to addition of surfactants and fatty acid. The temperature of the mix rises to around 50-60 ⁰ C at this point. After allowing to cool to <30C, the LR400 solution, PVP or PVP/PVI and remaining components such as perfume, preservatives, opacifier and dyes are added.

Example Formulations

Table 1

Softening Data

Formulations in table 2 were made according to the aforementioned method of production. The formulations were used to wash fabrics, which were then assessed for softness with a level of softness attributed to the washed fabrics. Softness testing took place in real washing machine tests conducted in typical European front-loading automatic machines. Washes were ~2 hours duration and included 2 rinses. Equal volumes of product (35ml) were tested.

The wash load consists of a 'ballast' portion made of cotton & poly-cotton sheets to achieve a 'standard' wash load weight of 2.5kg. The cloths actually used to check for softness are pieces of terry-towelling, previously pre-harshened, which measure -20 x 20cm. Cloths are line dried afterwards. 4 repeat washes are carried out to allow the softness effect to build up, after which the towelling monitors are assessed for softness. Softness assessment was carried out by a panel of volunteers. They were asked to rank the towels in order of softest to harshest, using a 7-point scale (1 =softest, 7=harshest). The scores for a given product were added up and the average value calculated.

The anionic surfactant used was LAS acid. This is neutralised in formulation to give sodium linear alkylbeneze sulphonate (NaLAS). The actual weight of anionic surfactant used is based on this neutralised form, and is therefore slightly higher than the formulation weight of LAS acid. LAS acid has an average molecular weight of 326.5 based on a formula of (CH ₃ (CH ₂ )IiC ₆ H ₄ SO ₃ H). NaLAS has molecular weight of 348.5 based on a formula of (CH ₃ (CH ₂ )i 1CeH ₄ SO ₃ Na). An example value of 1Og of LAS acid would have a total weight of anionic surfactant of 10.7g (based on the calculation (10g/326.5) x 348.5).

A comparative example (comparative A) was prepared according to

WO 2008/022838 examples 1 -3. According to the definitions herein, these example comprise nonionic surfactant at 12 wt.%, anonionic surfactant at 10.5 wt. % (made up from 7.5g NaLAS (rounded up from 10.47g) - i.e. the neutralised form of the acid + 3g of sodium xylenesulfonate, which is classed herein as both a surfactant and a hydrotrobe), 10g of fatty acid and 0.45g of cationic polymer. The total level of surfactant is 22.5g, the surfactant level as defined herein is not inclusive of the fatty acid or salt thereof. Comparative B was similar to A, but with the nonionic and anionic surfactant scaled up to -30% in total. Comparative examples C and D are further examples. The formulations were compared to a control formulation (Control) which did not contain any cationic polymer.

Table 2

The softening scores are presented as a lower score = a better softness level. As is clear from the table, formulations with a weight ratio of nonionic surfactant to anionic surfactant (NI:An ratio) within the range 1.25:1 to 2.25:1 are shown to have a superior effect on the softness of fabric when used in wash conditions.