Alkaline laundry liquid composition comprising sodium alkyl benzene sulphonate

Abstract

The present invention relates to an isotropic liquid detergent composition comprising, sodium alkyl benzene sulphonate, ethanolamine, secondary surfactant and hydrophilic solvent. The pH of the composition is from 9.5 to 13. The composition maintains the pH without use of buffering agents. Disclosed is an isotropic liquid detergent composition, comprising: a) sodium alkyl benzene sulphonate; b) an ethanolamine selected from monoethanolamine (MEA), diethanolamine (DEA) or triethanolamine (TEA), or a combination thereof; c) a secondary surfactant having HLB of 12 to 20 which is stable at pH 9.5 to 13; and, d) a hydrophilic solvent selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, sorbitol, glycerol or a combination thereof; wherein, said composition comprises sodium hydroxide in an amount such that pH of the composition is from 9.5 to 13, and ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1:1.

Description

[0001] Alkaline Laundry Liquid Composition

[0002] Field of the invention

[0003] The present invention relates to isotropic liquid detergent compositions for fabric wash, or alternatively for dishwash applications.

[0004] Background of the invention

[0005] Liquid laundry detergent compositions are available in a standard format containing about 4 to 20 wt% total surfactants, and the total surfactants is also referred to as the active detergent (AD) of such compositions.

[0006] Such compositions are also available in concentrated or super-concentrated formats (i.e., premix) suitable for 3X to 6X dilution by water to form ready-to-use liquid laundry detergent compositions. The concentrated and super-concentrated versions may contain 30 to 65 wt% AD (active detergent also known as total surfactants). Concentrated compositions are also suitable for use in laundry pods, which contain a unit dose of the composition packaged in a water-soluble film, especially a PVOH film. The unit dose pod can be added directly into a front or top load washing machine during the wash cycle. Likewise, liquid machine dish wash compositions are formulated on similar lines.

[0007] Liquid laundry detergent compositions are isotropic clear liquids where all the ingredients are usually solubilised in the carrier.

[0008] Usually, the pH of such isotropic liquid detergent compositions is around 7.0 or it could be slightly alkaline around 8.0. Alkaline formulations clean better than neutral compositions and are especially effective against tough stains deposited on soiled fabrics. However, such highly alkaline isotropic aqueous detergents are difficult to formulate and maintain in a stable condition.

[0009] Generally, such compositions are based on linear alkyl benzene sulphonates in which sulphonic acid groups of the corresponding sulphonic acid precursor are neutralised by a base such as sodium hydroxide . The hydroxide is preferred for neutralisation over carbonate because hydroxide is more soluble in water and is a stronger base than the carbonate. WO2023151991 Al (Unilever) discloses dilutable concentrated laundry premix containing non-ionic and anionic surfactants. In an exemplary embodiment, LABSA i.e., linear alkylbenzene sulphonic acid is added to brine, water, propylene glycol, glycerin, triethanolamine, NaOH (60% of amount required for complete neutralisation) to cause partial neutralisation of LAS acid with NaOH, and the unreacted LAS acid is further neutralised with the remaining part of NaOH. The pH of this composition is nearly neutral.

[0010] Other publications disclose compositions having linear alkyl benzene sulphonic acid having ammoniacal counteraction, (e.g., TEA-LAS) which is the triethanolamine salt of LABSA. Formulations containing such surfactants may become turbid upon dilution with water.

[0011] WO2022128372 Al (Unilever) discloses concentrated detergent comprising up to 5 wt% water, anionic surfactant, non-ionic surfactant, a fatty amide and a solvent. LAS (sulphonic) acid is neutralised by MEA (monoethanolamine) without adding water, and the resultant paste is heated to 60°C followed by addition of fatty amide and non-ionic surfactant. The ratio of anionic to non-ionic surfactant is about 1: 1 parts by weight. The formulations contain equimolar amounts of LAS acid and MEA.

[0012] WO2023235369 Al (Lubrizol) discloses dilution-thickening surfactant concentrates and cleaning compositions prepared from them. The concentrate comprises a surfactant chassis comprising a nonionic surfactant comprising a fatty alcohol ethoxylate and a polysorbate, and additionally alkylbenzene sulfonate. The composition comprises polyethoxylated alkyl glucoside ester.

[0013] EP0243685 Al (Lanza) discloses laundry detergent composition in which LABSA acid is neutralised with TEA. The pH is about 7.

[0014] EP2670788 Bl (Unilever, 2013) discloses aqueous alkaline isotropic concentrated detergent liquid composition with an undiluted pH between 7.8 and 9. The LAS (linear alkyl benzene sulphonic) acid is, at least in part, neutralised with TEA (triethanolamine).

[0015] EP3143111 Bl (Unilever, 2017) discloses an aqueous alkaline hand dishwash liquid comprising 9 to 20 wt% of a surfactant system comprising a linear alkyl benzene sulfonate and alkyl ether sulphate. The pH is 9.1 to 11 achieved through buffers selected from sodium / potassium carbonate or bicarbonate, provided with a sufficient buffering capacity to maintain the alkaline pH during the cleaning process. The composition does not contain ethanolamine.

[0016] W02009078868 Al (Colgate-Palmolive) discloses a cleaning composition comprising a buffering system comprising a strong base and an organic acid, such that pH of the composition is 9 to 13, an alkanolamine and a surfactant. The composition is useful to remove bumt-on and / or baked-on soil deposits and grease. Buffers and buffering systems are used to resist changes in pH, thereby keeping the pH of the solution at or near a desired level.

[0017] Summary of the invention

[0018] There is need for alkaline isotropic detergent compositions for washing clothes as well as for dishwashing. However, despite the compositions disclosed in prior art, especially EP’ 111 and WO’868 in which pH beyond 9 is maintained by use of buffers, there is need for compositions that do not necessarily require buffering agents. The present inventors have observed that when an alkanolamine is used to neutralise the linear alkylbenzene sulphonic acid, the pH can increase only up to around 9.3. That is presumably due to the inherent buffering ability of the alkanolamines.

[0019] The present inventors have determined that to formulate stable compositions with pH 9.5 to 13, especially 9.5 to 11, as per process of the invention, the alkyl benzene sulphonic acid should be first neutralized completely, or nearly completely, with an ethanolamine, example, triethanolamine, (to form the LAB SA-TEA salt or also known as LAS-TEA or TEA-LAS) until the pH is from 7 to about 9. The molar ratio of alkyl benzene sulphonic acid to ethanolamine should preferably be 1:0.8 to 1: 1.35.

[0020] Thereafter, sodium hydroxide should be added in stoichiometric excess, but in a regulated amount, to allow the formation of Na-LABSA (also known as Na-LAS / LAS-Na) which gets formed when LABSA-TEA reacts with NaOH, such that pH of the composition increases to 9.5 to 13.

[0021] In an alternative manner, the alkyl benzene sulphonic acid should be first neutralized completely, or nearly completely, with an ethanolamine, example, triethanolamine, (to form the LABSA-TEA salt or also known as LAS-TEA or TEA-LAS) until the pH is from 7 to about 7.5. Thereafter, sodium hydroxide should be added in stoichiometric excess, but in a regulated amount, to allow the formation of Na-LABSA (also known as Na-LAS / LAS- Na) which gets formed when LABSA-TEA reacts with NaOH, such that pH of the composition increases to 9.5 to 13.

[0022] Then all of LABSA-TEA is converted to LAS-Na due to reaction between LABSA-TEA and NaOH, and the pH of the composition increases to 9.5 to 13, depending on the molar excess of sodium hydroxide.

[0023] The ethanolamine reacted with LABSA is released which serves as free ethanolamine in the composition of the invention. The compositions of the invention are isotropic clear liquids.

[0024] A composition is said to be isotropic when it has liquid layers of one dimension and is transparent.

[0025] In accordance with a first aspect, disclosed is an isotropic liquid detergent composition, comprising: a) sodium alkyl benzene sulphonate; b) an ethanolamine selected from monoethanolamine (MEA), diethanolamine (DEA) or triethanolamine (TEA), or a combination thereof; c) a secondary surfactant having HLB of 12 to 20 which is stable at pH 9.5 to 13; and, d) a hydrophilic solvent selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, sorbitol, glycerol or a combination thereof; wherein, said composition comprises sodium hydroxide in an amount such that pH of the composition is from 9.5 to 13, and ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1: 1.

[0026] In accordance with a second aspect, disclosed a kit-of-parts comprising: a) package comprising an isotropic liquid detergent composition of the first aspect, as a dilutable concentrated detergent composition; b) a bottle to accommodate a corresponding ready-to-use detergent composition diluted with water; and, c) instructions regarding dilution.

[0027] In accordance with a further aspect, disclosed is a packaged product comprising a bottle comprising a volume of isotropic liquid detergent composition of the first aspect in the form of a dilutable concentrated detergent composition where said bottle comprises an indicia to aid a user regarding dilution with a recommended volume of water.

[0028] In accordance with a further aspect, disclosed is a laundry pod comprising at least a unit dose of an isotropic liquid detergent composition of the first aspect contained in a water- soluble film, where said isotropic liquid detergent composition comprises 2 to 15 wt% water.

[0029] Detailed description of the invention

[0030] These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word “comprising” is intended to mean “including” but not necessarily “consisting of’ or “composed of.” In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight / weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material or conditions of reaction, physical properties of materials and / or use are to be understood as modified by the word “about”. Numerical ranges expressed in the format “from x to y” are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format “from x to y”, it is understood that all ranges combining the different endpoints are also contemplated. In other words, in specifying any ranges of values, any upper value can be associated with any lower value.

[0031] The composition of the invention

[0032] The composition of the invention is an isotropic liquid detergent composition. Preferably the isotropic aqueous detergent composition of the invention comprises 10 to 70 wt% water. The amount of water depends on the nature of the composition and the intended application; for example, a concentrated composition for (do-it-yourself) DIY dilutable use at home would comprise lesser water. On the other hand, a ready to use format comprises comparatively more water.

[0033] The term detergent composition means that the composition of the invention is suitable for those applications which need detergency. Therefore, in one aspect of the invention the composition of the invention is a laundry detergent composition. In an alternative aspect the composition is a dishwash composition which is suitable for hand or machine dish wash.

[0034] The composition of the invention comprises sodium alkyl benzene sulphonate. The sulphonate serves as the primary surfactant, primarily responsible for detersive action.

[0035] It is preferred that the composition of the invention comprises 8 to 45 wt% sodium alkyl benzene sulphonate. More preferably the composition comprises 10 to 40 wt% sodium alkyl benzene sulphonate. Further, preferably the composition of the invention comprises 20 to 35 wt% sodium alkyl benzene sulphonate.

[0036] Preferably in the sodium alkyl benzene sulphonate, the alkyl chain has 8 to 20 carbon atoms, more preferably C12 to C18 alkyl groups. Suitable alkyl benzene sulphonic acid (LAB SA) is obtained by sulphonating commercially available linear alkyl benzene (LAB).

[0037] Commercial LABSA sulphonic acid is available in a 90% strength and 96% strength, each containing an active LABSA content as indicated per the %. The balance in each case is usually some water and some free sulphuric acid which in the 90% variant could be about 5%. Therefore, during commercial production of sodium alkyl benzene sulphonate, the free sulphuric acid content must be taken into consideration (i.e. must also be neutralised by the neutralising agent, e.g., triethanolamine). Therefore, an appropriately calculated excess of the neutralising agent must be used to neutralise the free sulphuric acid also.

[0038] Preferably the isotropic liquid detergent composition of the invention does not comprise more than 2 wt% salt of alkyl benzene sulphonic acid neutralised with any of the ethanolamines. In such cases, corresponding precursor, i.e. the alkyl benzene sulphonic acid is not neutralized with ethanolamine in the finished product, i.e. in the final composition.

[0039] For example, in the laundry detergent composition disclosed in EP0243685 Al (Lanza), the LAB SA acid is neutralised with TEA (triethanolamine).

[0040] Ethanolamine

[0041] The isotropic liquid detergent composition of the invention comprises an ethanolamine selected from monoethanolamine (MEA), diethanolamine (DEA) or triethanolamine (TEA) or a combination thereof. Preferably the ratio of moles of the sodium alkyl benzene sulphonate to the moles of the ethanolamine is 1:0.8 to 1: 1.35. More preferably the ratio is 1:0.9 to 1: 1.2. In the most preferred embodiment, this ratio is 1: 1.

[0042] It is preferred that in the isotropic liquid detergent composition of the invention, the ethanolamine is triethanolamine (TEA).

[0043] Sodium hydroxide and pH

[0044] The isotropic aqueous detergent composition of the invention comprises sodium hydroxide in an amount such that pH of the composition is from 9.5 to 13, and ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1: 1. More preferably the isotropic liquid detergent composition of the invention comprises sodium hydroxide in an amount such that pH of the composition is from 9.5 to 12.0. More preferably the ratio of moles of the ethanolamine to the moles of the sodium hydroxide is 1:0.3 to 1:0.95.

[0045] The sodium hydroxide referred to is the free sodium hydroxide in the composition. As such, the pH of the composition could be customised based on NaOH content. It is necessary that a strong base is used as against a weak base such as Na-carbonate which, in comparison, is not as water-soluble as well.

[0046] The inventors have observed that when the ratio of moles of the ethanolamine to the moles of the sodium hydroxide is 1 : 0.2 to 1 : 1 , the ethanolamine tends to remain solubilised in the composition and the rate at which it tends to separate out and manifest as crystals is controlled and not so much accelerated by any change in temperature or the extent of storage.

[0047] However, when the ratio increases beyond 1: 1, e.g., 1: 1.2 in favour of more sodium hydroxide, the pH of the composition does not increase significantly but the rate of separation of the ethanolamine is accelerated. That might lead a formulation scientist to an inference that excessive NaOH may destabilise the composition.

[0048] Therefore, without being bound by theory it is believed that when the isotropic aqueous detergent composition of the invention comprises sodium hydroxide in an amount such that pH of the composition is from 9.5 to 13, and ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1: 1, the composition is more stable.

[0049] It is especially preferred that the isotropic liquid detergent composition does not comprise buffering system of strong base and organic acid. Such a buffering system is described inter-alia in W02009078868 Al (Colgate-Palmolive).

[0050] The secondary surfactant

[0051] The composition of the invention comprises a secondary surfactant having HLB of 12 to 20 which is stable under the pH, i,e., pH 9.5 to 13. Preferably the composition comprises 3 to 15 wt% of the secondary surfactant.

[0052] HLB (Hydrophile Lipophile Balance) is calculated using the Griffin method wherein HLB = 20 x Mh / M wherein Mh is the molecular mass of the hydrophilic portion of the molecule and M is the molecular mass of the whole molecule, giving a result on an arbitrary scale of 0 to 20.

[0053] In general, published literature indicates as follows:

[0054] HLB <10: Lipid soluble (water insoluble)

[0055] HLB>10: Water soluble

[0056] HLB from 4 to 8 indicates an anti-foaming agent

[0057] HLB from 7 to 11 indicates a W / O (water in oil) emulsifier

[0058] HLB from 12 to 16 indicates oil in water emulsifier

[0059] HLB 11 to 14 indicates a wetting agent HLB from 12 to 15 is typical of detergents

[0060] HLB from 16 to 20 indicates a solubiliser or hydrotrope

[0061] Preferably the secondary surfactant is selected from the group consisting of alkyl glucoside (HLB 15 to 16), alkyl polyglucoside (HLB 15 to 16), sucrose ester (HLB 12 to 20), sorbitan ester (HLB 12 to 20), sulphobetaine, or amine oxides or a combination thereof. Preferably the secondary surfactant is alkyl glucoside or alkyl polyglucoside.

[0062] Alkyl glucosides can be represented by the formula RO — (G)n, wherein R is a branched or straight chain C8 to C20 alkyl group which may be saturated or unsaturated, G is a monosaccharide, and n is the degree of polymerisation which is 1 to 10. It is preferred that G is glucose and n is from 1 to 6.

[0063] Alkyl polyglucosides are biodegradable nonionic surfactants. Alkyl polyglycoside surfactants are commercially available in a large variety. They are biodegradable and plant- derived from sugars, and these surfactants are usually glucose derivatives and fatty alcohols. An example is Planteren® APG 600 (Trademark) Ex Henkel Corporation and Triton® CG-425 Ex. Dow.

[0064] Sucrose esters are the esters of sucrose and C12-24 fatty acids, preferably C12-22. The sucrose esters are selected from monoester, di-ester, tri-ester, tetra-ester or a mixture thereof. Preferably, the fatty acids are selected from those having saturated alkyl group having the above numbers of carbon atoms. The sucrose ester may be a blend of two or more sucrose esters. Preferably the sucrose ester is a blend of sucrose laurate and sucrose dilaurate. An example of sucrose ester is Sucrose Dilaurate BC 10034 available from BASF.

[0065] It is preferred that the composition of the invention comprises 2 to 15 wt% tertiary surfactant selected from alpha olefins sulphonate, methyl ester sulphonate, sodium lauryl sulphate, sodium lauryl ether sulphate or betaine. More preferably the tertiary surfactant is sodium lauryl sulphate or betaines. It is preferred that the isotropic liquid detergent composition of the invention comprises 20 to 65 wt% total surfactants, wherein the sodium alkyl benzene sulphonate is 40 to 75 parts by weight of the total surfactants.

[0066] The total surfactants include the sodium alkyl benzene sulphonate, which serves as the primary surfactant, the secondary surfactant and tertiary surfactant if any.

[0067] Hydrophilic solvent

[0068] The isotropic liquid detergent composition of the invention comprises a hydrophilic solvent selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, sorbitol, glycerol or a combination thereof. Preferably the hydrophilic solvent is polyethylene glycol or propylene glycol or a combination thereof. Preferably the composition comprises 4 to 10 wt% solvent.

[0069] Water

[0070] Preferably the isotropic liquid detergent composition comprises 10 to 70 wt% water.

[0071] Sodium sulphate

[0072] The composition of the invention preferably comprises an amount of sodium sulphate. The sodium sulphate is generated insitu when, as per process of the invention, the free sulphuric acid in the commercial LAB SA acid reacts with sodium hydroxide. The amount of sodium sulphate that gets formed in-situ depends on the grade of commercial LAB SA acid used in the process. Commercial LABSA acid containing 90% active LABSA acid contains little more sulphuric acid as compared to Commercial LABSA acid containing 96% active LABSA acid. Such calculations and amounts are well known to persons skilled in the art of detergent formulations. However, if a commercial manufacturer is able to procure LABSA acid totally free of sulphuric acid, then the resulting liquid detergent composition will not contain sodium sulphate unless it is added separately. Additional preferred ingredients

[0073] Anti-Foam

[0074] The isotropic aqueous detergent composition preferably comprises an anti-foam. Anti-foam agents are well known in the art and include silicones and fatty acids.

[0075] Preferably, where present, the fatty acid anti-foam is present at from 1.3 to 3.0, more preferably from 1.4 to 2.0 wt% and most preferably from 1.6 to 2.0 wt%. Suitable fatty acids include aliphatic carboxylic acids of formula RCOOH, where R is a linear or branched alkyl or alkenyl chain containing from 6 to 24, more preferably 10 to 22, most preferably from 12 to 18 carbon atoms and 0 or 1 double bond. Preferred examples of such materials include saturated C12 to 18 fatty acids such as lauric acid, myristic acid, palmitic acid or stearic acid; and fatty acid mixtures in which 50 to 100% (by weight based on the total weight of the mixture) consists of saturated C12 to 18 fatty acids. Such mixtures may typically be derived from natural fats and / or optionally hydrogenated natural oils (such as coconut oil, palm kernel oil or tallow).

[0076] Any fatty acid may be present in the form of their sodium, potassium or ammonium salts and / or in the form of soluble salts of organic bases, such as mono-, di- or triethanolamine.

[0077] HASE polymer

[0078] It is preferred that the isotropic liquid detergent composition of the invention comprises a HASE polymer. Hydrophobically modified alkali swellable emulsion (HASE) polymers are a type of synthetic associative rheology modifiers. This rheology modifier typically contains a backbone consisting of randomly distributed methacrylic acid (MAA) and ethyl acrylate (EA) monomers, amongst other possible monomer components. This backbone contains small proportion of hydrophobically modified groups, usually less than 3 mol%. Dissolution in an alkaline medium induces a variety of interacting forces such as hydrophobic, hydrogen bonding, electrostatic, etc and this modifies the rheology of the liquid. HASE copolymers are usually synthesized via the emulsion polymerization technique. Preferably the composition of the invention comprises 0.5 to 5 wt% of a HASE polymer. Sequestrant

[0079] The isotropic liquid detergent composition of the invention preferably comprises 0.05 to 4 wt% sequestrant such as alkali metal citrates, succinates, malonates and carboxymethyl succinates. Specific examples include DEQUEST® grade of sequestrants.

[0080] Cleaning polymers

[0081] The isotropic liquid detergent composition of the invention preferably comprises 0.05 to 5 wt% anti-redeposition polymer., e.g., alkoxylated polyethyleneimines with an average degree of ethoxylation of 10 to 30.

[0082] Soil release and other polymers

[0083] The isotropic liquid detergent composition of the invention preferably comprises 0.01 to 5 wt% soil release polymer (SRP). The SRP may be selected from copolyesters of dicarboxylic acids (for example adipic acid, phthalic acid or terephthalic acid), diols (for example ethylene glycol or propylene glycol) and polydiols (for example polyethylene glycol or polypropylene glycol).

[0084] Structuring agents

[0085] The isotropic liquid detergent composition of the invention may have the rheology modified by use of one or more structurant which forms a structuring network within the composition, such as hydrogenated castor oil or microfibrous cellulose. A structurant may provide shear thinning rheology and may also enable materials such as encapsulates and visual cues to be suspended stably in the liquid.

[0086] Enzymes

[0087] The isotropic liquid detergent composition preferably comprises an efficacious amount of an enzyme, or a cocktail of enzymes, selected from the group of pectate lyase, protease, amylase, cellulase, lipase, or mannanase. The enzymes are preferably present with corresponding enzyme stabilizers.

[0088] Fluorescent Agent

[0089] The isotropic aqueous detergent composition of the invention preferably comprises an optical brightener, preferably from 0.0001 to 0.5 wt% of the composition. Preferred fluorescers include Di-styryl biphenyl compounds, e.g., Tinopal® CBS-X, Di-amine stilbene di-sulphonic acid compounds, e.g., Tinopal® DMS pure Xtra and Blankophor® HRH, and pyrazoline compounds, e.g. Blankophor® SN.

[0090] Shading dyes

[0091] The isotropic liquid detergent composition of the invention preferably comprises a shading dye.

[0092] Dyes suitable for use generally have an extinction coefficient (Xmax) in the visible range (400 to 700 nm) of greater than 5000 L mol^cm’1. It is preferred that the chromophore in the dye is azo, azine, anthraquinone, phthalocyanine or triphenylmethane. Preferably the shading dye is a blue or violet shading dye. Such dyes deposit onto the cloth during the washing or rinsing step. When the composition comprises a shading dye, it is preferred that the amount is 0.0001 to 0.1 wt %. In general, the shading dye is incorporated as a formulation containing the dye and variety of other ingredients. An alternative and preferred way is to include the shading dye in liquid form.

[0093] Dye Transfer Inhibiting Agent

[0094] The isotropic liquid detergent composition of the invention preferably comprises a dye transfer inhibiting agent. Examples include polyvinylpyrrolidone polymers, polyamine N- oxide polymers, copolymers of N-vinylpyrrolidone and N-vinylimidazole, polyvinyloxazolidones, polyvinylimidazoles, manganese phthalocyanine, peroxidases, polyvinylpyrrolidone polymers, ethylene-diamine-tetraacetic acid (EDTA); diethylene triamine penta methylene phosphonic acid (DTPMP); hydroxy-ethane diphosphonic acid (HEDP). Other equivalent agents are known to persons skilled in the art.

[0095] Perfume

[0096] The isotropic liquid detergent composition of the invention preferably comprises a perfume. The perfume may be of synthetic origin. Alternatively, the perfume ingredients may be in the encapsulated form and a variety of products is available from suppliers such as Firmenich and IFF.

[0097] Properties

[0098] It is preferred that viscosity of the isotropic liquid detergent composition of the invention is at 25°C and at shear rate of 21 sec'1is 200 to 5,000 mPa.s [0.2 to 5 Pa.s.]. Viscosity could be measured by any method known in the art. Preferably it is determined using a Brookfield LV viscometer and measured using spindle #3 at 20 RPM. It is preferred that viscosity of isotropic liquid detergent composition of the invention when in the concentrated form at 25°C and at shear rate of 21 sec'1is 400 to 5,000 mPa.s [0.4 to 5 Pa.s.]. Rheological profile of the composition is such that it is amenable for manufacture, packaging, transportation, and display.

[0099] Where the composition of the invention is in the form of a dilutable concentrate, preferably the viscosity of corresponding diluted (i.e., post-dilution at home) composition is 50 to 1500 mPa.s [0.05 to 0.8 Pa.s.], preferably from 200 to 800 mPa.s [0.2 to 0.8 Pa.s.]. This composition is ready for use, i.e., ready for use for laundering clothes. It is preferred that dilution of 1 part by volume of the composition of the invention (concentrate) with three to five parts by volume water forms a laundry liquid detergent composition having viscosity at 25°C and at shear rate of 21 sec'1of 200 to 800 mPa.s [0.2 to 0.8 Pa.s.].

[0100] A kit-of-parts:

[0101] In another aspect the invention relates to a kit-of-parts comprising: a) a package comprising an isotropic liquid detergent composition of the first aspect, as a dilutable concentrated detergent composition; b) a bottle to accommodate a corresponding ready-to-use detergent composition diluted with water; and, c) instructions regarding dilution.

[0102] Unit dose pods

[0103] The composition of the invention could also be offered in the form of a laundry pod. Accordingly in one aspect of the invention is provided a laundry pod comprising at least a unit dose of an isotropic liquid detergent composition of the first aspect contained in a water-soluble film, where said isotropic liquid detergent composition comprises 2 to 15 wt% water. Preferably the water-soluble material is alkali-stable such that it can hold the alkaline composition and remain stable.

[0104] Packaged product

[0105] In accordance with another aspect, disclosed is a packaged product comprising a bottle comprising a volume of isotropic liquid detergent composition of the first aspect in the form of a dilutable concentrated detergent composition where the bottle comprises an indicia to aid a user regarding dilution with a recommended volume of water.

[0106] The indicia is preferably in the form of a line or symbol or clear demarcation indicating, for example, “pour water up to here” or an equivalent instruction. The composition of the invention may be packaged in a variety of packaging formats which depends on nature and purpose of the composition.

[0107] Isotropic liquid detergent compositions are usually packaged in bottles made of rigid plastic. The bottle containing the liquid can be of different sizes and shapes to accommodate different volumes of the liquid; preferably between 500 ml and 2 L. The bottle is preferably provided with a dispenser or a pour spout, which enables the consumer an easier mode of dispersion of the liquid. The bottles may be made entirely or partly by using recycled plastic material or at least recyclable material. Isotropic aqueous detergent composition of the invention may also be packaged in pouches, usually in large size, which serve as refdl pouches for pouring or emptying into the bottles.

[0108] In one aspect of the invention the composition is a laundry liquid detergent. Alternatively, the composition is a dishwash composition, especially a hand dishwash composition.

[0109] Other ingredients of the composition could be chosen or selected keeping the end use in mind.

[0110] Process of preparing the isotropic aqueous detergent composition

[0111] In accordance with yet another aspect of the invention, disclosed is a process of preparing an isotropic liquid detergent composition, comprising: a) reacting an amount of alkyl benzene sulphonic acid (LAB SA acid) with an ethanolamine selected from monoethanolamine (MEA), diethanolamine (DEA) or triethanolamine (TEA) or a combination thereof at molar ratio of 1:0.8 to 1: 1.35, in the presence of a hydrophilic solvent selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, sorbitol, glycerol or a combination thereof, and a secondary surfactant having HLB of 12 to 20 which is stable under pH of 9.5 to 13, b) allowing for formation of a salt of LAB SA acid with said ethanolamine; c) adding an amount of aqueous solution of sodium hydroxide to cause reaction of said salt of LAB SA acid with said ethanolamine with said sodium hydroxide to form a corresponding sodium alkyl benzene sulphonate with concomitant release of said ethanolamine from the salt of LABSA acid with ethanolamine as free ethanolamine, wherein, said sodium hydroxide is added in stoichiometric excess such that pH of said composition is from 9.5 to 13, and ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1: 1.

[0112] In summary, the chemical reactions that are involved in the process of the invention are as follows, taking TEA as an exemplary ethanolamine:

[0113] In step (a), the LABSA acid reacts with an ethanolamine at molar ratio 1:0.8 to 1: 1.35, (example triethanolamine TEA) to form the corresponding TEA salt.

[0114] (salt as per step b)

[0115] In step (c), the LABSA-TEA acid reacts with NaOH to form Na-LAS and the TEA is concomitantly released to get incorporated as free TEA in the composition.

[0116] The free sodium hydroxide which is in stoichiometric excess over that required for the reaction in step (c) ensures that pH is in the range 9.5 to 13. The moles of stoichiometric excess of NaOH determines the pH of the composition.

[0117] In both the steps (a) and (c), it is necessary to factor in that commercial LABSA is not available in 100% active basis and that it contains free sulphuric acid which remains from the process of sulphonation using oleum or equivalent thereof.

[0118] In general, a 90% active commercial grade LABSA contains 90% LABSA and about 5% sulphuric acid. Similar information can be found about the 96% grade. Therefore, when LABSA is to be neutralised or reacted with a base such as ethanolamine or even for that mater sodium hydroxide, the formulation chemists should ensure an appropriate overdose of the base to first neutralise the sulphuric acid present in the commercial product in addition to the active wt% of LAB SA acid.

[0119] The invention will now be explained in detail with the help of the following non-limiting examples of compositions of the invention and a process of the invention.

[0120] Examples

[0121] Example 1 - Compositions

[0122] A series of compositions 1, 2, 3 and 4 were prepared as detailed in Table 1. All compositions were as per the invention.

[0123] Composition 1 and 2 did not contain any tertiary surfactant. Compositions 3 and 4 were prepared as alternative formulations within the invention containing additional tertiary surfactants, SLS or CAPB as applicable, whilst still maintaining pH in the range of 9.5 to 13.0.

[0124] The pH of Composition 1 was 10.3, while the same was increased to 13.0 in Composition 2.

[0125] For comparison, a composition with pH greater than 13.0 was prepared (Composition A) which was found to be turbid, i.e. not isotropic, presumably due to excessive NaOH over the amount of Triethanolamine. All other compositions were clear, isotropic to begin with.

[0126] Table 1

[0127] Information about Moles of triethanolamine (TEA) and NaOH in compositions of Table 1 is included in Table 2.

[0128] Molecular weight of TEA = 149 g / mol; Molecular weight of NaOH = 40 g / mol *HLAS is the acid precursor of Na-LAS

[0129] Table 2

[0130] Note:

[0131] The actual amount of lauryl glucoside has been indicated. It is available in the form of 50% strength / active material, the balance being water which gets incorporated into the composition(s). The corresponding LABSA was of commercial grade containing 90% active and actual Na-LAS formed has been included in the table.

[0132] It was observed that the compositions 1 to 4 were stable for longer period at room temperature whereas the composition A showed evidence of crystals of free TEA after a few hours of preparation of the composition.

[0133] It was believed that the high alkalinity coupled with absence of pH buffer could possibly destabilise the compositions of the invention as in Table 1.

[0134] Therefore, a representative composition (1) was selected for stability studies in which samples of the composition were stored under varied conditions of temperature and relative humidity (RH). This experiment was carried out for three weeks at a stretch and after the end of each week the samples were removed from respective storage cabinets and observed. After the observations were recorded the samples were kept back in their cabinets and the experiment continued. All the observations are shown in Table 3. RH stands for relative humidity.

[0135] Table 3 The data in Table 3 clearly indicates that the pH remained constant, and the composition remained clear and isotropic under all test conditions without any phase separation or salting-out effect or crystal formation of TEA that is usually expected from unstable compositions.

[0136] Example 2: Comparative

[0137] A series of compositions as per Table 4 were prepared.

[0138] Table 4 The data in Table 4 clearly indicates that addition of excess TEA leads to an effect like salting out because the excess TEA crystallises out. This experiment demonstrates the additional need to keep molar ratio of sodium alkyl benzene sulphonic acid to the ethanolamine at 1:0.8 to 1: 1.35.

[0139] The observations pertaining to comparative formulation C indicates that simply adding stoichiometric excess of NaOH does not provide a technical solution. It is necessary to have an appropriate amount of ethanolamine also. Even an excess of ethanolamine leads to further technical problems as demonstrated by the observations pertaining to comparative formulation B.

[0140] Example 4: Process

[0141] An isotropic liquid laundry detergent composition was prepared with the following ingredients as the input raw materials.

[0142] Table 5

[0143] As per the process for preparing an isotropic liquid detergent composition, in step (a)

[0144] The commercial LASBA acid (alkyl benzene sulphonic acid (LABSA acid)) was reacted with all the triethanolamine (TEA), in presence of a hydrophilic solvent (propylene glycol) and the secondary surfactant (lauryl glucoside).

[0145] The chemical reaction between LABSA acid and the triethanolamine, led to formation of the corresponding salt. At this stage pH of the mass was little over 7. Thereafter in step (b), the aqueous solution of sodium hydroxide was added which caused reaction with the salt of LABSA acid with triethanolamine to form a corresponding sodium alkyl benzene sulphonate with concomitant release of triethanolamine from the salt of LABSA acid with triethanolamine as free triethanolamine.

[0146] As the triethanolamine was gradually released back into the mass, the pH increased gradually to 9.2. Addition of sodium hydroxide in stoichiometric excess raised the pH of said composition further to 9.5 to 13.

[0147] The illustrated examples indicate that the present invention addresses the need for isotropic liquid detergent compositions for washing clothes or for dishwashing that do not necessarily require buffering agents to maintain pH from 9.5 to 13.0. The examples illustrate the observation that when an alkanolamine is used to neutralise the linear alkylbenzene sulphonic acid, the pH may increase only upto and around 9.3. Additional strong base such as sodium hydroxide keeps the pH around 9.3. The examples illustrate that to formulate stable compositions with pH 9.5 to 13, especially 9.5 to 12, the alkyl benzene sulphonic acid should be first neutralized completely, or nearly completely, with an ethanolamine, such that molar ratio of alkyl benzene sulphonic acid to the ethanolamine is 1:0.8 to 1: 1.35. Thereafter, an amount of sodium hydroxide should be added in stoichiometric excess over the molar ratio of TEA salt of alkyl benzene sulphonic acid, such that the composition comprises sodium hydroxide in an amount such that pH of the composition is from 9.5 to 13, and ratio of moles of the ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1: 1. Then all, or practically all of LAS-TEA is converted to LAS-Na, i.e., sodium alkyl benzene sulphonate wherein alkyl benzene sulphonic acid is neutralized with sodium hydroxide, the pH of the composition increases to 9.5 to 13.0, depending on the molar excess of sodium hydroxide. In this case, an equimolar amount of the ethanolamine is released which serves as free ethanolamine.

Claims

CLAIMS1) An isotropic liquid detergent composition, comprising: a) sodium alkyl benzene sulphonate; b) an ethanolamine selected from monoethanolamine (MEA), diethanolamine (DEA) or triethanolamine (TEA), or a combination thereof; c) a secondary surfactant having HLB of 12 to 20 which is stable at pH 9.5 to 13; and, d) a hydrophilic solvent selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, sorbitol, glycerol or a combination thereof; wherein, said composition comprises sodium hydroxide in an amount such that pH of the composition is from 9.5 to 13, and ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1: 1.2) The isotropic liquid detergent composition as claimed in claim 1, wherein said composition comprises 8 to 45 wt% sodium alkyl benzene sulphonate.3) The isotropic liquid detergent composition as claimed in claim 1 or 2 wherein said composition comprises 5 to 25 wt% of said ethanolamine.4) The isotropic liquid detergent composition as claimed in any of claims 1 to 3 wherein ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.3 to 1:0.95.5) The isotropic liquid detergent composition as claimed in any of claims 1 to 4, wherein said composition does not comprise buffering system of strong base and organic acid.6) The isotropic liquid detergent composition as claimed in any of claims 1 to 5, wherein said composition comprises less than 2 wt% of salt of alkyl benzene sulphonic acid neutralized with any of said ethanolamine.7) The isotropic liquid detergent composition as claimed in any of claims 1 to 6 wherein said secondary surfactant is selected from the group consisting of alkyl glucoside, alkyl polyglucoside, sucrose ester, sorbitan ester, sulphobetaine, amine oxides or a combination thereof.8) The isotropic liquid detergent composition as claimed in any of claims 1 to 7 wherein said composition comprises 3 to 15 wt% of said secondary surfactant.9) The isotropic liquid detergent composition as claimed in any of claims 1 to 8, wherein said hydrophilic solvent is polyethylene glycol or propylene glycol or a combination thereof.10) The isotropic liquid detergent composition as claimed in any of claims 2 to 9, wherein said composition comprises 10 to 40 wt% of said sodium alkyl benzene sulphonate.11) The isotropic liquid detergent composition as claimed in any of claims 1 to 10 wherein said ethanolamine is triethanolamine (TEA).12) The isotropic liquid detergent composition as claimed in any of claims 1 to 11 wherein said composition comprises 10 to 70 wt% water.13) The isotropic liquid detergent composition as claimed in any of claims 1 to 12 wherein said composition comprises 2 to 15 wt% tertiary surfactant selected from the group consisting of alpha olefin sulphonate, methyl ester sulphonate, sodium lauryl sulphate, sodium lauryl ether sulphate, betaine, or a combination thereof.14) The isotropic liquid detergent composition as claimed in any of claims 2 to 13, wherein said composition comprises total of 20 to 65 wt% surfactants, wherein said sodium alkyl benzene sulphonate accounts for 40 to 75 parts by weight of said total surfactants.15) The isotropic liquid detergent composition as claimed in any of claims 1 to 14, wherein viscosity of said composition at shear rate of 21 sec'1and at 25°C is 200 to 5,000 mPa.s [0.2 to 5 Pa.s.].16) The isotropic liquid detergent composition as claimed in any of claims 1 to 15, wherein said composition is:(a) a ready-to-use detergent composition; or,(b) a dilutable concentrated detergent composition, where dilution of 1 part by volume of said composition with three to five parts by volume water forms a corresponding ready-to-use detergent composition having viscosity at shear rate of 21 sec'1and at 25°C of 200 to 5000 mPa.s [0.2 to 5 Pa.s.].17) A kit-of-parts comprising: a) a package comprising an isotropic liquid detergent composition as claimed in claim 1, as a dilutable concentrated detergent composition; b) a bottle to accommodate a corresponding ready-to-use detergent composition diluted with water; and, c) instructions regarding dilution.18) A packaged product comprising a bottle comprising a volume of an isotropic liquid detergent composition as claimed in claim 1 in the form of a dilutable concentrated detergent composition, where said bottle comprises an indicia to aid a user regarding dilution with a recommended volume of water.19) A laundry pod comprising at least a unit dose of an isotropic liquid detergent composition as claimed in claim 1 contained in a water-soluble film, where said isotropic liquid detergent composition comprises 2 to 15 wt% water.20) A process of preparing an isotropic liquid detergent composition, comprising: a) reacting an amount of alkyl benzene sulphonic acid (LAB SA acid) with an ethanolamine selected from monoethanolamine (MEA), diethanolamine (DEA) or triethanolamine (TEA) or a combination thereof at molar ratio of 1:0.8 to 1: 1.35, in the presence of a hydrophilic solvent selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, sorbitol, glycerol or a combination thereof, and a secondary surfactant having HLB of 12 to 20 which is stable under pH of 9.5 to 13, b) allowing for formation of a salt of LAB SA acid with said ethanolamine;c) adding an amount of aqueous solution of sodium hydroxide to cause reaction of said salt of LABSA acid with said ethanolamine with said sodium hydroxide to form a corresponding sodium alkyl benzene sulphonate with concomitant release of said ethanolamine from the salt of LABSA acid with ethanolamine as free ethanolamine, wherein, said sodium hydroxide is added in stoichiometric excess such that pH of said composition is from 9.5 to 13, and ratio of moles of said ethanolamine to the moles of said sodium hydroxide is 1:0.2 to 1: 1.

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