CLEAR SOFTENER FORMULATIONS

FIELD OF THE INVENTION

The present invention generally relates to mixtures of cationic surfactants useful for preparing optically transparent softening compositions; compositions comprising such mixtures; and their use for softening fabrics and/or fibres.

BACKGROUND OF THE INVENTION

Quaternary ester ammonium compounds, commonly referred to as “esterquats” (EQ), have found broad use as fabric softener actives due to their high softening performance (e.g., for softening textile fibers and fabrics as well as keratinous fibers, such as hair), their biodegradability, reasonably low aquatic toxicity, and good cosmetic compatibility with the skin.

However, common softener formulations comprising with esterquats have the disadvantage of being turbid and not clear (optically transparent). Optical transparency is a highly desirable property of softening compositions, and is important for the visual appeal of such products. Particularly desirable are esterquat formulations that form clear solutions in water. Additionally, such solutions should be stable upon storage.

While there are attempts in the state of the art aiming at related objectives, there remains a demand for surfactant mixtures capable of providing softening formulations meeting the above requirements even at relatively low EQ concentrations, and which do not necessitate the excessive use of solvents or further additives.

In WQ2016096614A1 , a fabric treatment agent comprising specific esterquats is described. However, an optically clear, fabric softener formulation with high storage stability is provided only in the additional presence of cationic thickeners and non-ionic emulsifiers.

In view of the above, the present invention aims at the problem of providing new cationic surfactant mixtures allowing to prepare clear and stable softener formulations when mixed with water below 40 °C, preferably at room temperature, and preferably even in the absence of further additives. Additionally, it is preferable that such formulations exhibit advantageous storage stability under various conditions, advantageous handleability (simple handling), and/or advantageous softening properties.

SUMMARY OF THE INVENTION

As a solution to the above problems, the present invention provides a mixture of cationic surfactants is obtainable from a process comprising the steps: Step I: esterification of a) with b), and Step II: cation formation from the reaction products of Step I, wherein: a) is a hydroxyl group-containing compound or a mixture of hydroxyl group-containing compounds comprising a.1 and optionally a.2, wherein:

- a.1 is an alkanolamine or a mixture of alkanolamines of the general formula (I): R ³

R ² — O(CHCH2O) _n H

R ¹ — N (I)

R ² — O(CHCH2O) _n H

R ³ in which R ¹ is selected from hydrogen, a C-j-Cg alkyl group, and the residue - R ² -O(CHCH ₂ O) _n H

R ³

R^ is a C-j-Cg alkylene group, R® is hydrogen or methyl, n is 0 or an integer from 1 to 20; and a.2 is a polyol, which can be optionally alkoxylated, and is characterized by a MW in the range 60 to 190 g/mol; b) is a mixture of compounds containing one or more carboxylic groups comprising b.1 and b.2, wherein: b.1 is a monocarboxylic acid or a mixture of monocarboxylic acids of formula (II):

R ⁶ -COOH (II) in which R® is a linear or branched Cg-C23 alkyl or alkenyl group; or an alkyl ester or glyceride thereof, preferably a linear or branched Cg-C23 alkyl or alkenyl ester; and b.2 is a dicarboxylic acid or a mixture dicarboxylic acids of the general formula (III), or reactive derivative(s) thereof: HOOC — L— COOH (III) wherein L is a saturated or unsaturated, linear, branched or cyclic group having 1 to 10 carbon atoms, each of which carbon atoms is optionally substituted by a C-j-Cg saturated or unsaturated group; and is preferably represented by (CH(R ⁷ )) _m or by (Cg- C-| Q arylene) optionally substituted by one or more R ⁷ , in which each R ⁷ is independently a hydrogen, OH or a C-j-Cg saturated or unsaturated group, m is 0 or an integer from 1 to 10, wherein for m > 2, the chain (CH) _m optionally contains one or more double bonds and/or cyclic group(s); wherein a.1), a.2), b.1) and b.2) are introduced in the reaction system of Step I in amounts resulting in the following molar ratios:

- the molar ratio of monoacid(s)/diacid(s) (b.1 /b.2) is 0.10 to 1.0;

- the molar ratio between organic carboxylic groups and organic hydroxyl groups (COOH/OH) present in the system is 0.30 to 0.80; and

- the molar ratio between the compound(s) within the definition a.2 and the compound/s under definition a.1 is 0 to 0.5.

The present invention further provides use of the above mixture for preparing an optically transparent composition, e.g., by mixing with water. The present invention further provides a softener composition, e.g., a fabric-softening and/or keratin-based- fibres-softening composition, comprising the above mixture; as well as a concentrated softener composition comprising such mixture.

The present invention further provides use of the softener composition(s) for softening fabrics and/or keratin-based-fibres.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have surprisingly found that particular mixtures of cationic surfactants (esterquats (EQ)) obtainable by reacting a combination of mono- and di-carboxylic acids with alkanolamine(s) and optionally polyol(s), and subsequent cation formation, form clear, optically transparent solutions in water at room temperature. These effects can be observed even in the absence of further additives, and without the necessity to use high EQ or solvent concentrations.

Mixtures of cationic surfactants

The cationic surfactant mixtures of the present invention can be directly dissolved in water, thereby providing softener compositions that are optically transparent and stable upon storage under various conditions. No additives are necessary for achieving the optical transparency and stability of the final compositions.

The cationic surfactant mixtures of the present invention can be used to formulate clear fabric softener compositions below 40°C, preferably below 30°C, more preferably below 25°C, and at 20 °C or more, most preferably at 20 °C. Addition of non-ionic surfactants and solvents is optional, not necessary for, and not affecting the optical transparency of the final composition. Optical transparency is an attractive and desirable feature of the products. Using less adititives is advantageoous from of environmental, bio- and skin compatibility, and economical perspective.

In an embodiment of the invention, the molar ratio of monoacid(s)/diacid(s) (b.1/b.2) is 0.20 to 1.0, preferably 0.30 to 1 .0; and/or the molar ratio between organic carboxylic groups and organic hydroxyl groups (COOH/OH) present in the system is 0.40 to 0.70, preferably 0.50 to 0.70; and/or the molar ratio between the compound(s) within the definition a.2 and the compound/s under definition a.1 is 0 or 0.1 to 0.5, preferably 0.1 to 0.5. Without wishing to be bound by theory, each of these particular ratios is may even further improve the optical transparency. Additionally, handleability (simple handling), and/or softening properties may be improved.

In an embodiment of the invention, the alkanolamine(s) of formula (I) is/are selected from triethanolamine, N-methyldiethanolamine, N-methyldiisopropanolamine and triisopropanolamine, each of which is optionally alkoxylated with ethylene oxide or propylene oxide, and mixtures thereof.

In an embodiment of the invention, in the dicarboxylic acid(s) of formula (III), each L is selected from ethane- 1 ,2-diyl, 1-hydroxyethane-1 ,2-diyl, c/s-ethene-1 ,2-diyl, trans-ethene-1 ,2-diyl, propane-1 ,2-diyl, propane- 1 ,3-diyl, butane-1 ,4-diyl, pentane-1 ,5-diyl, hexane-1 ,6-diyl, cyclohexane-1 ,4-diyl, octane-1 ,8-diyl and 1 ,4- phenylenyl; preferably butane-1 ,4-diyl, hexane-1 ,6-diyl or octane-1 ,8-diyl.

In an embodiment of the invention, the dicarboxylic acid of formula (III) is selected from succinic, malic, glutaric, adipic, sebacic, pimelic, suberic, maleic and terephthalic acid, acids obtained by thermal oligomerisation of unsaturated fatty acids, and mixtures thereof.

In an embodiment of the invention, the reactive derivative(s) of the dicarboxylic acid(s) of the general formula (III) are one or more selected from halide, anhydride, preferably mixed anhydride with acetic acid or cyclic anhydride.

The inventors have surprisingly found out that by using the particular ratios of the components as in the present invention, it is possible to obtain cationic surfactant mixtures allowing to prepare clear and stable softener formulations when mixed with water below 40°C, preferably below 30°C, more preferably below 25°C, and at 20 °C or more, most preferably at 20 °C, even when using a broader variety of monocarboxylic acid(s) than in the prior art.

For example, the monocarboxylic acid(s) of formula (II) are synthetic fatty acids and/or are obtained from fats or oils of natural origin, and are optionally hydrogenated; or are derived from oils of vegetal origin which are optionally hydrogenated.

In an embodiment of the invention, the monocarboxylic acid(s) of formula (II) are selected from those which are obtained from tallow, palm, olive, coconut, sunflower, soya, rapeseed, grape marc and grape, each of which can be hydrogenated, partially hydrogenated, or non-hydrogenated.

In an embodiment of the invention, the iodine value of the carboxylic monoacid(s) of formula (II) is preferably > 5, more preferably > 35, even more preferably > 45, most preferably > 50; and/or preferably < 280, more preferably < 180, even more preferably < 100, most preferably < 80. Preferably, the iodine value of the carboxylic monoacid(s) of formula (II) is 5-280, more preferably 5-180, more preferably 35-180, more preferably 45-100, more preferably 45-80, most preferably 50-80. Without wishing to be bound by theory, using carboxylic monoacid(s) having such iodine values may contribute to even further improving the optical transparency at various temperatures, and/or the storage stability of the aqueous formulations obtained from the mixture of cationic surfactants according to the present invention.

In an embodiment of the invention, the carboxylic monoacid(s) of formula (II) is one or more selected from caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, eleostearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid, and mixtures thereof which are obtained for example by pressure splitting of natural fats and oils, in the reduction of aldehydes from Roelen's oxosynthesis or dimerization of unsaturated fatty acids, stearic acids, isostearic acid, palmitic acid, myristic acid, lauric acid, capric acid, caprylic acid, 2-ethylhexanoic acid, 2- octyldodecanoic acid, capric acid, oleic acid, linoleic acid, linolenic acid, partially hydrogenated coconut fatty acid, palm fatty acid, partially hydrogenated distilled palm fatty acid, hydrogenated distilled palm fatty acid, palm kernel fatty acid, tallow fatty acid, distilled tallow fatty acid, and rapeseed fatty acid.

In an embodiment of the invention, the compounds corresponding to a.1 and/or a.2 can be from natural origin or from synthetic origin.

In an embodiment of the invention, the polyol a.2 is one or more selected from trimethylolpropane (TMP), glycerine, neopentyl glycol (NPG) and sorbitol, each of which can be optionally alkoxylated, preferably ethoxylated; wherein the polyol a.2 is more preferably trimethylolpropane (TMP), or is absent.

Step I is and esterification step of reacting a) with b). In an exemplary embodiment, monoacid b.1 and diacid b.2 are combined with alkanolamine a.1 and optionally the polyol b.2. The obtained mixture is heated. Preferably, the mixture is heated to reflux under atmospheric pressure, e.g., for 1-5, preferably 2-4 hours at 140-200 °C, preferably 160-180°C. Preferably, step I is performed until no more water is distilled off the reaction mixture.

The reaction product obtained from step I is subjected to cation formation in step II. Preferably, an organic solvent is added before step II. Step II can corresponds to the formation of the addition salts of the alkanolamine esters obtained from Step I with mineral or organic acids, preferably wherein the mineral or organic acids are one or more selected from hydrochloric, sulphuric, phosphoric, citric and lactic acid. Alternatively, Step II can corresponds to the quaternisation of reaction mixtures of Step I with alkylating agent(s), preferably wherein the alkylating agents are one or more selected from methyl chloride, methyl bromide, dimethyl sulphate, diethyl sulphate and dimethyl carbonate. Step II can be performed at room temperature or elevated temperature, e.g., 40-100 °C, preferably 50-90 °C; preferably for 1-5, more preferably 2-4 hours, or until the virtually complete absence of amine value was verified by acid/base assay.

In an embodiment of the invention, the mixture further comprises an organic solvent, preferably an alcohol, more preferably ethanol, n-propanol or isopropanol, butanols, glycol, propane or butanediol, glycerol, diglycol, propyl or butyl diglycol, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, propylene glycol methyl, ethyl or propyl ether, dipropylene glycol methyl or ethyl ether, methoxy, ethoxy or butoxy triglycol, 1-butoxyethoxy-2-propanol, 3-methyl-3-methoxybutanol, or propylene glycol t- butyl ether. For instance, such solvent may be added during the preparation step, e.g., before, during and/or after II, preferably before Step II.

In an embodiment of the invention, the content of the organic solvent in the cationic surfactant mixture is 0-30%, preferably 0-20%, more preferably 10-20% by weight.

In an embodiment of the invention, the mixture is essentially water-free. In an embodiment of the invention, the mixture essentially consists of the reaction products of steps I and II, and optionally an organic solvent. Preferably, the mixture consists of the reaction products of steps I and II and solvent, if any, and unreacted starting materials as well as inevitable impurities from the production process, if any.

Softener compositions

Further provided is a softener composition, preferably a fabric-softening and/or keratin-based-fibres- softening composition, comprising the cationic surfactant mixture according to the invention. The composition preferably further comprises water.

Such compositions exhibit may advantageous storage stability under various conditions, as well as further advantageous properties, such as handleability (simple handling) and/or softening properties.

Such compositions are clear solutions at RT, and can be stable upon storage RT, or 5°C, or at 40°C, e.g., for at least 2 months.

In an embodiment of the invention, the composition is optically transparent at room temperature, and preferably also at temperatures of 26-40 °C, more preferably 20-50 °C, even more preferably 16-50 °C, most preferably 5-60 °C.

In the composition, the water content is preferably higher than 50%, more preferably higher than 80%, most preferably higher than 85% w/w. The solid residue is preferably lower than 50%, more preferably lower than 25%, even more preferably between 15 and 2%. Clear diluted formulations are preferably formulated with 2-20% of solid residue (e.g., EQ + optional nonionic surfactant), and a minimum water content of 75%.

In an embodiment of the invention, the composition further comprises a perfume. The perfume consists of one or more substance(s). The average logP of the perfume substance(s) is from 1 to 6, preferably from 1 to 4, preferably from 2 to 4. The weight ratio between the cationic surfactant mixture according to the invention, as defined hereinabove, and the perfume is from 99:1 to 40:60, more preferably from 80:20 to 60:40, even more preferably 80:20 to 70:30.

In an embodiment of the invention, the composition further comprises a non-ionic surfactant. The weight ratio between the cationic surfactant mixture and the non-ionic surfactant is preferably from 100:0 (i.e., no non-ionic surfactant is present) to 70:30. A non-ionic surfactant can advantageously improve solubility of a perfume in the composition, especially when high amounts of perfume are used (e.g., > 1 %, optionally up to 3% by weight of the composition, or more). Preferably, when the amount of perfume in the composition is 0.3% by weight or less, no non-ionic surfactant is used; otherwise, a non-ionic surfactant may optionally be used. Additionally, the addition of a non-ionic surfactant can even further improve the good stability of the formulation upon storage.

In an embodiment of the invention, the composition further comprises a thickener, e.g., a thickening polymer. The weight ratio the cationic surfactant mixture to the thickener is preferably from 100:0 to 10:5, more preferably from 100:1 to 10:2. A thickener may be added to increase the viscosity of the composition. Suitable thickeners are, e.g., PEG-150 distearate, Hydroxyethyl cellulose, hydroxymethyl cellulose and derivatives thereof, PEG-120 Methyl Glucose Dioleate, PEG-120 Methyl Glucose Trioleate (and) propanediol, ethoxylated Sorbitan Triisostearate (e.g., PEG-160 Sorbitan Triisostearate, such as Kaopan TW IS-559S from Kao Chemicals Europe, S.L.), and copolymers of acrylamide and dimethyl amino ethyl methacrylate methyl chloride cross- methylene bisacrylamide (such as FLOSOFT 222 manufactured by SNF).

In an embodiment of the invention, the composition comprises: (i) the mixture of cationic surfactants as described hereinabove, and (ii) optionally one or more non-ionic surfactants, wherein the sum of components (i) and (ii) is from 2% to 20% by weight, and wherein: the content of component (i) is from 2% to 20%, preferably from 5 to 15% by weight, relative to the weight of the composition; and the content of component (ii) is from 0% to 10%, preferably from 0 to 7%; more preferably from 0 to 5%, even more preferably 0 to 2%, most preferably 0 to 0.05% by weight, relative to the weight of the composition.

Preferred embodiments of compositions according to the invention comprise, preferably essentially consist, more preferably consist of: esterquats (EQ) and water; or EQ, water and thickener; or EQ, water and up to 3.0% by weight of perfume; or EQ, water, non-ionic surfactant(s) and perfume; or EQ, water, thickener, and perfume; or EQ, organic solvent, such as ethanol or glycerine, and perfume.

Preferred embodiments of water-free compositions according to the invention comprise, preferably essentially consist, more preferably consist of: esterquats (EQ); or EQ and thickener; or EQ and perfume; or EQ, non-ionic surfactant(s) and perfume; or EQ, thickener, and perfume; or EQ, organic solvent, such as ethanol or glycerine, and perfume.

The present invention further provides a concentrated softener composition comprising the cationic surfactant mixture as described hereinabove, and having a water content lower than 20%, preferably lower than 10%, more preferably lower than 5%. Such composition can be liquid and transparent at temperature from 26-60 °C, preferably 20-40 °C, more preferably 16-60 °C, most preferably 0-80 °C. Particularly good transparency is achieved at a water content lower than 5%, preferably 0-5% w/w, most preferably in the absence or essential absence of water.

In a particularly preferred embodiment, the liquid and transparent compositions comprise the mixture of cationic surfactants as described hereinabove in an amount of 1 to 20% (diluted composition), or >95% w/w (concentrated composition).

In an embodiment of the invention, the concentrated softener composition further comprises:

A) a perfume, preferably wherein:

(i) the perfume consists of one or more substance(s); and/or

(ii) the average logP of the perfume substance(s) is from 1 to 6; and/or (iii) the perfume can be an encapsulated perfume, preferably the perfume is encapsulated in a biodegradable microcapsule, more preferably the microcapsule is based on chitosan; and/or

B) a non-ionic surfactant, which is preferably characterised in that the weight ratio of the described components are values according to the following ratios:

P:C is a value from 0:100 to 60:40 NI:C is from 0:100 to 30:70

P corresponds to the perfume, optionally microencapsulated perfume;

C corresponds to the cationic surfactant mixture;

Nl corresponds to the non-ionic surfactant.

As used herein, the non-ionic surfactants) can be selected from fatty acids, linear or branched, alkoxylated or non-alkoxylated esters of fatty acids, especially those containing from 8 to 18 carbon atoms, alkoxylated or non-alkoxylated Guerbet alcohols, optionally alkoxylated glycerol and polyglycerol esters, xylitol esters, alkoxylated or non-alkoxylated sorbitan esters, esters of sugars, such as glucose, fructose, galactose, mannose, xylose, arabinose, ribose, 2-deoxyribose and sucrose, Cs-18 fatty alcohols, alkyl polyglucosides, non-ionic surfactants with amide groups derived from amines, such as glucamine, and the derivatives of methylethanolamine, diethanolamine, isopropanolamine and monoethanolamine, with linear or branched fatty acids, especially those containing from 8 to 18 carbon atoms, waxes, such as paraffins, microcrystalline waxes derived from petroleum, and synthetic waxes, and pentaerythritol esters, especially having a tallow, hydrogenated tallow, palm, behenic or oleic chain, preferably non-ionic surfactants are selected from glycerine esters that are ethoxylated, sorbitan monoesters and pentaerythritol esters, especially those having a tallow, hydrogenated tallow, palm, behenic or oleic chain.

Suitable non-ionic surfactants are Glycereth-6 Cocoate (e.g., Levenol F-200), Glycereth-17 Cocoate (e.g., Levenol C-201 ), ethoxylated C-j 3.-] 5 alcohol (e.g., with 7EO, such as Findet 1315/19), ethoxylated C-j g.-j g alcohol (e.g., with 23 EG, such as Findet 1618/35); particularly suitable is ethoxylated hydrogenated castor oil (e.g., with 40 EO, such as Findet ARH-52).

The softener composition or the concentrated softener composition may have a viscosity at 20 °C of 2- 50,000 cps, as measured on a Brookfield LVT viscometer with spindle 2 at 60 rpm or with spindle 4 at 12 rpm. Preferably, such compositions have a viscosity of 2 to 5,000 mPas as measured on a Brookfield LVT viscometer with spindle 4 at 12 rpm, optionally 2 to 800 mPas; or have a viscosity of 2 to 800 mPas as measured on a Brookfield LVT viscometer with spindle 2 at 30 rpm.

For example, concentrated EQ and their mixtures with Nl, perfume and/or glycols can have a viscosity values between 100 and 50000 mPa s. Diluted formulations (from 2% active to 50% active) can have viscosity values between 2 and 500 mPa s. Uses

The present invention further provides the use of the cationic surfactant mixture as described hereinabove for preparing an optically transparent composition, and process for preparing an optically transparent composition from said mixture is also provided, e.g., comprising combining the mixture with water. The thus obtained composition can be used in a method for softening fabrics and/or keratin-based-fibres, comprising a step of contacting the composition of any one of aspects 25-36 with the fabrics and/or fibres.

Additionally, the concentrated transparent composition can be used for softening fabrics and/or keratin- based-fibres. That is, a fabric softener can be prepared by a user by directly mixing the composition with tap water, or by introducing the composition directly into a washing machine.

The present invention further provides the following aspects.

1 . A mixture of cationic surfactants obtainable from a process comprising the steps: Step I: esterification of a) with b), and

Step II: cation formation from the reaction products of Step I, wherein: a) is a hydroxyl group-containing compound or a mixture of hydroxyl group-containing compounds comprising a.1 and optionally a.2, wherein:

- a.1 is an alkanolamine or a mixture of alkanolamines of the general formula (I):

R ³

R ² — O(CHCH2O) _n H

R ¹ — N (I)

R ² — O(CHCH2O) _n H

R ³ in which R ¹ is selected from hydrogen, a C-j-Cg alkyl group, and the residue

- R ² -O(CHCH ₂ O) _n H

R ³

R^ is a C-j-Cg alkylene group, R® is hydrogen or methyl, n is 0 or an integer from 1 to 20; and a.2 is a polyol, which can be optionally alkoxylated, and is characterized by a MW in the range 60 to 190 g/mol; b) is a mixture of compounds containing one or more carboxylic groups comprising b.1 and b.2, wherein: b.1 is a monocarboxylic acid or a mixture of monocarboxylic acids of formula (II):

R ⁶ -COOH (II) in which R® is a linear or branched Cg-C23 alkyl or alkenyl group; or an alkyl ester or glyceride thereof, preferably a linear or branched Cg-C23 alkyl or alkenyl ester; and b.2 is a dicarboxylic acid or a mixture dicarboxylic acids of the general formula (III), or reactive derivative(s) thereof:

HOOC — L— COOH (III) wherein L is a saturated or unsaturated, linear, branched or cyclic group having 1 to 10 carbon atoms, each of which carbon atoms is optionally substituted by a C-j-Cg saturated or unsaturated group; and is preferably represented by (CH(R ⁷ )) _m or by (Cg-C-j g arylene) optionally substituted by one or more R ⁷ , in which each R ⁷ is independently a hydrogen, OH or a C-j-Cg saturated or unsaturated group, m is 0 or an integer from 1 to 10, wherein for m > 2, the chain (CH) _m optionally contains one or more double bonds and/or cyclic group(s); wherein a.1), a.2), b.1) and b.2) are introduced in the reaction system of Step I in amounts resulting in the following molar ratios:

- the molar ratio of monoacid(s)/diacid(s) (b.1/b.2) is 0.10 to 1 .0;

- the molar ratio between organic carboxylic groups and organic hydroxyl groups (COOH/OH) present in the system is 0.30 to 0.80; and

- the molar ratio between the compound(s) within the definition a.2 and the compound/s under definition a.1 is 0 to 0.5.

2. The mixture according to aspect 1 , wherein the molar ratio of monoacid(s)/diacid(s) (b.1/b.2) is 0.20 to 1 .0, preferably 0.30 to 1 .0.

3. The mixture according to any one of the preceding aspects, wherein the molar ratio between organic carboxylic groups and organic hydroxyl groups (COOH/OH) present in the system is 0.40 to 0.70, preferably 0.50 to 0.70.

4. The mixture according to any one of the preceding aspects, wherein the molar ratio between the compound(s) within the definition a.2 and the compound/s under definition a.1 is 0 or 0.1 to 0.5, preferably 0.1 to 0.5.

5. The mixture according to any one of the preceding aspects, wherein the amounts of the compounds a.1 , a.2, b.1 and b.2 are introduced in the reaction system of Step I in amounts that result in the following molar ratios:

- the molar ratio of monoacid(s)/diacid(s) (b.1 /b.2) is 0.30 to 1 .0;

- the molar ratio between organic carboxylic groups and organic hydroxyl groups (COOH/OH) present in the system is 0.40 to 0.70, preferably 0.50 to 0.70; and

- the molar ratio between the compound(s) within the definition a.2 and the compound/s under definition a.1 is 0, or is 0.1 to 0.5.

6. The mixture according to any one of the preceding aspects, wherein the alkanolamine(s) of formula (I) is/are selected from triethanolamine, N-methyldiethanolamine, N-methyldiisopropanolamine and triisopropanolamine, each of which is optionally alkoxylated with ethylene oxide or propylene oxide, and mixtures thereof.

7. The mixture according to any one of the preceding aspects, wherein in the dicarboxylic acid(s) of formula (III), each L is selected from ethane-1 ,2-diyl, 1-hydroxyethane-1 ,2-diyl, c/s-ethene-1 ,2-diyl, trans- ethene-1 ,2-diyl, propane-1 ,2-diyl, propane-1 ,3-diyl, butane-1 ,4-diyl, pentane-1 ,5-diyl, hexane-1 ,6-diyl, cyclohexane-1 ,4-diyl, octane-1 ,8-diyl and 1 ,4-phenylenyl; preferably butane-1 ,4-diyl, hexane-1 ,6-diyl or octane-1 ,8-diyl.

8. The mixture according to any one of the preceding aspects, wherein the dicarboxylic acid of formula (III) is selected from succinic, malic, glutaric, adipic, sebacic, pimelic, suberic, maleic and terephthalic acid, acids obtained by thermal oligomerisation of unsaturated fatty acids, and mixtures thereof.

9. The mixture according to any one of the preceding aspects, wherein the reactive derivative(s) of the dicarboxylic acid(s) of the general formula (III) are one or more selected from halide, anhydride, preferably mixed anhydride with acetic acid or cyclic anhydride.

10. The mixture according to any one of the preceding aspects, wherein the monocarboxylic acid(s) of formula (II) are synthetic fatty acids and/or are obtained from fats or oils of natural origin, and are optionally hydrogenated.

11 . The mixture according to any one of the preceding aspects, wherein the monocarboxylic acid(s) of formula (II) are derived from oils of vegetal origin which are optionally hydrogenated.

12. The mixture according to any one of the preceding aspects, wherein the monocarboxylic acid(s) of formula (II) are selected from those which are obtained from tallow, palm, olive, coconut, sunflower, soya, rapeseed, grape marc and grape, each of which can be hydrogenated, partially hydrogenated, or nonhydrogenated.

13. The mixture according to any one of the preceding aspects, wherein the iodine value of the carboxylic monoacid(s) of formula (II) is preferably > 5, more preferably > 35, even more preferably > 45, most preferably > 50; and/or preferably < 280, more preferably < 180, even more preferably < 100, most preferably < 80.

14. The mixture according to any one of the preceding aspects, wherein the iodine value of the carboxylic monoacid(s) of formula (II) is 5-280, more preferably 5-180, more preferably 35-180, 35-100, more preferably 45-100, more preferably 45-80, most preferably 50-80.

15. The mixture according to any one of the preceding aspects, wherein the carboxylic monoacid(s) of formula (II) is one or more selected from caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, eleostearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid, and mixtures thereof which are obtained for example by pressure splitting of natural fats and oils, in the reduction of aldehydes from Roelen's oxosynthesis or dimerization of unsaturated fatty acids, stearic acids, isostearic acid, palmitic acid, myristic acid, lauric acid, capric acid, caprylic acid, 2-ethylhexanoic acid, 2-octyldodecanoic acid, capric acid, oleic acid, linoleic acid, linolenic acid, partially hydrogenated coconut fatty acid, palm fatty acid, partially hydrogenated distilled palm fatty acid, hydrogenated distilled palm fatty acid, palm kernel fatty acid, tallow fatty acid, distilled tallow fatty acid, and rapeseed fatty acid.

16. The mixture according to any one of the preceding aspects, wherein the compounds corresponding to a.1 and/or a.2 are from natural origin.

17. The mixture according to any one of the preceding aspects, wherein the compounds corresponding to a.1 and/or a.2 are from synthetic origin.

18. The mixture according to any one of the preceding aspects, wherein Step II corresponds to the formation of the addition salts of the alkanolamine esters obtained from Step I with mineral or organic acids, preferably wherein the mineral or organic acids are one or more selected from hydrochloric, sulphuric, phosphoric, citric and lactic acid.

19. The mixture according to any one of aspects 1-17, wherein Step II corresponds to the quaternisation of reaction mixtures of Step I with alkylating agent(s), preferably wherein the alkylating agents are one or more selected from methyl chloride, methyl bromide, dimethyl sulphate, diethyl sulphate and dimethyl carbonate.

20. The mixture according to any one of the preceding aspects, wherein the polyol a.2 is one or more selected from trimethylolpropane (TMP), glycerine, sorbitol and neopentyl glycol (NPG), each of which can be optionally alkoxylated, preferably ethoxylated; wherein the polyol a.2 is more preferably trimethylolpropane (TMP), or is absent.

21 . The mixture according to any one of the preceding aspects, further comprising an organic solvent, preferably an alcohol, more preferably ethanol, n-propanol or isopropanol, butanols, glycol, propane or butanediol, glycerol, diglycol, propyl or butyl diglycol, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, propylene glycol methyl, ethyl or propyl ether, dipropylene glycol methyl or ethyl ether, methoxy, ethoxy or butoxy triglycol, 1-butoxyethoxy-2-propanol, 3-methyl-3-methoxybutanol, or propylene glycol t-butyl ether.

22. The mixture according to aspect 21 , wherein the content of the organic solvent is 0-30%, preferably 0-20%, more preferably 10-20% by weight. 23. The mixture according to any one of the preceding aspects, wherein the mixture is essentially water-free.

24. The mixture according to any one of the preceding aspects, wherein the mixture essentially consists of the reaction products of steps I and II, and optionally an organic solvent.

25. The mixture according to any one of the preceding aspects, wherein the mixture consists of the reaction products of steps I and II and solvent, if any, and unreacted starting materials as well as inevitable impurities from the production process, if any.

26. A softener composition, preferably a fabric-softening and/or keratin-based-fibres-softening composition, comprising the cationic surfactant mixture according to any one of the preceding aspects.

27. The composition according to aspect 26, further comprising water.

28. The composition according to aspect 26 or 27, which is optically transparent at room temperature, and preferably at temperatures of 26-40 °C, more preferably 20-50 °C, even more preferably 16-50 °C, most preferably 5-60 °C.

29. The composition according to any one of aspects 26-28, wherein: the water content is preferably higher than 75%, more preferably higher than 80%, more preferably higher than 85%, most preferably higher than 90% w/w; and/or the solid residue is 25% or less, preferably 20% or less, more preferably 15% or less, even more preferably 10% or less; most preferably 2 to 10% w/w.

30. The composition according to any one of aspects 26-29, further comprising:

A) a perfume, preferably wherein:

(i) the perfume consists of one or more substance(s); and/or

(ii) the average logP of the perfume substance(s) is from 1 to 6; and/or

(iii) the weight ratio between the cationic surfactant mixture and the perfume is from 99:1 to 40:60, more preferably from 80:20 to 60:40, even more preferably 80:20 to 70:30; and/or

(iv) the perfume can be partially encapsulated, preferably the perfume is encapsulated in a biodegradable microcapsule, more preferably the microcapsule is based on chitosan; and/or

B) a non-ionic surfactant, the weight ratio between the cationic surfactant mixture and the nonionic surfactant is from 100:0 to 70:30; and/or

C) a thickener, wherein the weight ratio of the mixture according to aspect 1 to 25 to the thickener is from 100:0 to 10:5, preferably from 100:1 to 10:2

31 . The composition according to 26-30 comprising:

(i) the mixture of cationic surfactants as defined in any one of aspects 1 to 25, and

(ii) optionally one or more non-ionic surfactants, in which the sum of components (i) and (ii) is from 2% to 20% by weight, wherein, the content of component (i) is from 2% to 20%, preferably from 5 to 15% by weight, relative to the weight of the composition; and the content of component (ii) is from 0% to 6%, preferably from 0 to 4%; more preferably from 0 to 3%, even more preferably 0 to 2%, most preferably 0 to 0.05% by weight, relative to the weight of the composition..

32. A concentrated softener composition comprising the cationic surfactant mixture according to any one of aspects 1 to 25, and having a water content lower than 20%, preferably lower than 10%, preferably lower than 5%.

33. The composition of aspect 32, which is liquid and transparent at temperature from 26-60 °C, preferably 20-40 °C, more preferably 16-60 °C, most preferably 0-80 °C.

34. The composition according to aspect 32 or 33, further comprising:

A) a perfume, preferably wherein:

(i) the perfume consists of one or more substance(s); and/or

(ii) the average logP of the perfume substance(s) is from 1 to 6; and/or

(iii) the perfume can be an encapsulated perfume, preferably the perfume is encapsulated in a biodegradable microcapsule, more preferably the microcapsule is based on chitosan; and/or

B) a non-ionic surfactant; and/or

C) characterised in that the weight ratio of the described components are values according to the following ratios:

P:C is a value from 0:100 to 60:40 NI:C is from 0:100 to 30:70

P corresponds to the perfume, optionally microencapsulated perfume;

C corresponds to the cationic surfactant mixture according to any of aspects 1 to 25; Nl corresponds to the non-ionic surfactant.

35. The composition according to aspect 30, 31 or 34, wherein the non-ionic surfactant(s) are selected from fatty acids, linear or branched, alkoxylated or non-alkoxylated esters of fatty acids, especially those containing from 8 to 18 carbon atoms, alkoxylated or non-alkoxylated Guerbet alcohols, optionally alkoxylated glycerol and polyglycerol esters, xylitol esters, alkoxylated or non-alkoxylated sorbitan esters, esters of sugars, such as glucose, fructose, galactose, mannose, xylose, arabinose, ribose, 2-deoxyribose and sucrose, Cs-18 fatty alcohols, alkyl polyglucosides, non-ionic surfactants with amide groups derived from amines, such as glucamine, and the derivatives of methylethanolamine, diethanolamine, isopropanolamine and monoethanolamine, with linear or branched fatty acids, especially those containing from 8 to 18 carbon atoms, waxes, such as paraffins, microcrystalline waxes derived from petroleum, and synthetic waxes, and pentaerythritol esters, especially having a tallow, hydrogenated tallow, palm, behenic or oleic chain, preferably non-ionic surfactants are selected from glycerine esters that are ethoxylated, sorbitan monoesters and pentaerythritol esters, especially those having a tallow, hydrogenated tallow, palm, behenic or oleic chain.

36. The composition according to any one of aspects 26-35, preferably 32-35, characterised in having a viscosity at 20 °C of 200-50,000 cps, as measured on a Brookfield LVT viscometer with spindle 2 at 60 rpm or with spindle 4 at 12 rpm.

37. The composition according to aspect 36, wherein the composition:

A) has a viscosity of 200 to 5,000 mPas as measured on a Brookfield LVT viscometer with spindle

4 at 12 rpm, optionally 200 to 800 mPas; or

B) the composition has a viscosity of 200 to 800 mPas as measured on a Brookfield LVT viscometer with spindle 2 at 30 rpm.

38. Use of the mixture of any one of aspects 1-25 for preparing an optically transparent composition; or a process for preparing an optically transparent composition from the mixture of any one of aspects 1-25.

39. The use or process according to aspect 38, comprising combining the mixture with water.

40. Use of the composition of any one of aspects 26-37 for softening fabrics and/or keratin-based- fibres, or a method for softening fabrics and/or keratin-based-fibres comprising a step of contacting the composition of any one of aspects 36-37 with the fabrics and/or fibres.

41 . Use of the composition of any one of aspects 32-37 for softening fabrics and/or keratin-based- fibres comprising preparing a fabric softener by mixing the composition with tap water, or comprising introducing the composition directly into a washing machine; or a method for preparing a fabric softener suitable for softening fabrics and/or keratin-based-fibres comprising mixing the composition with tap water, or introducing the composition directly into a washing machine.

As used herein, “clear” or “optically transparent” appearance of a mixture/composition/formulation refers to essentially complete optical transmittance, e.g., preferably > 90%, more preferably > 95%, even more preferably > 98%, most preferably > 99%. Preferably, and unless specified otherwise, the optical transmittance of such mixture/composition/formulation is measured at = 600 nm (1 cm thickness, 20 °C).

As used herein, in cases where a ratio (e.g., molar ratio) “x/y” between compound(s) within a first definition “x” and compound(s) under a second definition “y” is 0, this means that compounds within the first definition “x” are absent or essentially absent.

As used herein, and unless specified otherwise, “stable” or “stable upon storage” refer to compositions comprising the cationic surfactant mixture according to the present invention which maintain essentially complete optical transmittance as described above immediately after their preparation and after storage. Preferably, the compositions are stable over at least 7 days at 20 °C; over at least 7 days at 5 °C; over at least 14 d at 20 °C; over at least 28 days at 20 °C; or over at least 28 days at 40 °Cs.

As used herein, viscosity is measured on a Brookfield LVT viscometer at 20 °C with a spindle 2 at 30 or 60 rpm (preferably: for low viscosities), or with a spindle 4 at 12 rpm (preferably: for high viscosities).

As used herein, “iodine number” (or “iodine value”, IV) describes the degree of unsaturation, e.g., of a fatty acid, and can be determined according to EN 1411 1 :2003.

EXAMPLES

Example 1

Synthetic procedure

(i) Esterification:

115.1 grams (0.42 mol) of tallow fatty acid and 202.9 grams (1 .39 mol) of Adipic acid were introduced in an inert atmosphere into a glass reactor. Then, 292.3 g (1 .96 mol) of triethanolamine, together with 65.8 grams of Trimethylolpropane (0.49 mol) were introduced, which were added with stirring. The mixture was heated for at least 4 hours at 160-180°C in order to remove water from the reaction. The final point of the reaction is monitored by an acid value assay until the value was below 2 mg KOH/g.

A yellowish liquid product from the esterification was obtained, consisting essentially of a mixture of unesterified fatty acids and adipic acid, mono-, di- and triesterified triethanolamine with fatty acids, mono-, di- and triesterified triethanolamine with adipic acid or a combination thereof, mono-, di- and triesterified trimethylolpropane with fatty acids, mono-, di- and triesterified trimethylolpropane with adipic acid or a combination thereof, together with unreacted triethanolamine and trimethylolpropane.

(ii) Quaternisation:

611.5 grams of the product from esterification step (containing 1.94 mol of amine equivalent product) are mixed with 149.0 g of Ethanol (3.23 mol), then, 232.4 grams (1 .84 mol) of dimethyl sulphate were added with stirring at a temperature of 50-90 °C.

After four hours of digestion, the virtually complete absence of amine value was verified by acid/base assay. 992.9 grams of the final product was obtained.

Calculations

Molar ratio monocarboxylic acid I dicarboxylic acid:

0.42 mol tallow fatty acid / 1 .39 mol adipic acid = 0.30

Equivalents ratio COOH / OH: (1 eq * 0.42 mol tallow fatty acid + 2 eq * 1 .39 mol adipic acid) / (3 eq * 1 .96 mol triethanolamine +

3 eq * 0.49 mol trimethylolpropane) = 0.44

Molar ratio polyol / triethanolamine:

0.49 mol trimethylolpropane 1 1 .96 mol triethanolamine = 0.25

Example 2

Further exemplary EQ mixtures (Table 1 ) were prepared by a procedure analogous to that of Example 1 .

Table 1 : Exemplary EQ mixtures, and properties thereof

Mono/Di: Molar ratio monocarboxylic acid/dicarboxylic acid in step (i)

Monoacid: b.1 used in step (i)

COOH/OH: Equivalents ratio COOH/OH in step (i)

Diacid: diacid (b.2) used in step (i)

Polyol: component a.2 used in step (i)

Solubility measurement

88.3 g of deionized water at 20°C were added in a beaker provided with a magnetic stirrer at low stirring rate. Then, 11 .7 g of the respective EQ mixture were added while stirring at 20°C. The resulting mixture is stirred for 15 minutes at 20 °C. To quantify the optically transparent appearance, transmittance was measured at A = 600 nm (1 cm thickness, 20 °C) immediately after that (t = 0), or after various periods of storage and temperatures (Table 2).

Table 2. Transmittance measurement results

The results show that the EQ mixtures of the present invention can be directly dissolved in water, thereby providing compositions that are optically transparent and stable upon storage under various conditions. No additives are necessary for achieving the optical transparency and stability of the final compositions.

Example 3

Further exemplary EQ mixtures were prepared by a procedure analogous to that of Example 1 , and measured under the conditions of Example 2 (transmittance measured at A = 600 nm, 1 cm thickness, t = 0, 20 °C).

Table 4. Further EQ mixtures and transmittance measurement results

Mono/Di: Molar ratio monocarboxylic acid/dicarboxylic acid in step (i)

COOH/OH: Equivalents ratio COOH/OH in step (i)

Diacid: diacid (b.2) used in step (i)

Monoacid: monoacid (b.1 ) used in step (i)

TLH-D: Distilled tallow fatty acid / Edenor® Ti E GA, CYPACID TL-12

Palm PH: Partially hydrogenated distilled palm fatty acid / CYPACID P-50-H, Radiacid® 0438

Example 4

88.5g of distilled water are added at room temperature to a flask. 0.2 g of a thickening polymer (hydroxyethyl cellulose, NATROSOL 250 HHX) are added to the water and the mixture is left under stirring until homogeneity. Then, 10 g of the product of the present invention (EQ ref. 25106) are added on, and provided with proper stirring at room temperature. Mixture is left stirring for 15 minutes. Then, 1 g of commercially available LEVENOL C-201 is added to the mixture and it is left for 15 minutes under stirring. Once incorporated, 0.3 g of fragrance is added to the mixture under stirring. After 15 minutes, mixture is unloaded, and the mixture is left for 24 hours at room temperature before measuring transmittance at A = 600 nm, 1 cm thickness, and 20 °C (Tables 5 and 6).

The results show that the EQ mixtures of the invention can be used to formulate clear fabric softener compositions at 20°C. Addition of non-ionic surfactants and solvents is optional, not necessary for, and not affecting the optical transparency of the final composition. Table 5

Table 6

EQ (25633): See Table 1 for details. FINDET 1315/19 is C-13-15 alcohol 7EO, available from KAO Chemicals Europe.

LEVENOL C-201 is Glycereth-17 Cocoate, available from KAO Chemicals Europe.

LEVENOL F-200 is Glycereth-6 Cocoate, available from KAO Chemicals Europe.

Fragrance: BLUESKY SF154641 , available from KAO Chemicals Europe.