Fabric softening composition

Abstract: Environmentally acceptable liquid fabric softening compositions are provided which comprise a combination of an amine softening material, a fatty acid material and preferably a buffer acid.

Description: The present invention relates to a fabric softening composition, in particular to an aqueous based fabric softening composition containing one or more amines as active materials. It is known to treat fabrics, particularly after washing, with fabric softening agents in order to improve the feel of the fabrics and, in the case of clothes, to improve comfort in wear. Traditionally, fabric softening agents are applied from an aqueous liquor which is made up by adding a relatively small volume of a fabric softening composition to a large volume of water, for example during the rinse cycle in an automatic washing machine. The fabric softening composition is usually an aqueous liquid product containing a cationic fabric softening agent,most typically a quaternary ammonium salt such as ditallow dimethyl ammonium chloride. For a number of reasons it would be preferred if alternative softeners to the quaternary ammonium salts could be used in aqueous liquid products for example to replace or partially replace the quaternary ammonium salts with softeners which are most environmentally friendly or less costly, easier to handle or less prone to causing skin reaction. However this replacement or partial replacement with alternative softeners should maintain or substantially maintain the softening performance of the product. Amine fabric softening agents provide a potential solution to these problems however, one of the problems of amine containing fabric softener compositions for use in the rinse is that they often do not soften as well as compositions comprising quaternary ammonium softener materials. EP 0 043 622A (Procter and Gamble) discloses certain concentrated fabric softening compositions comprising water-insoluble imidazoline salts and a viscosity control system. EP 0 194 127 (Procter and Gamble) discloses a certain fabric softening composition comprising a tertiary amine softener and a soil release polymer for application to fabrics in a tumble dryer. GB 2 192 909 (Colgate-Palmolive) discloses certain detergent compositions for fabric washing which can comprise amine complexes to soften during the wash. EP 0 281 975 (Henkel) discloses fabric softening compositions comprising a carboxylic acid and an amine and/or quaternary ammonium compound. The document contains no teaching as to the pH's of the compositions. EP 0 206 375 (Unilever) discloses liquid detergent compositions for simultaneous cleaning and softening of fabrics. The compositions include a long-chain fatty amine softener; a nonionic and/or anionic detergent; and a hydrotropic agent. The pH of the composition is said to be below the isoelectric point of the amine component. It is an object of the present invention to formulate fabric softening compositions comprising one or more amines as the active materials. It is a further object of the present invention to provide fabric softening compositions which are environmentally acceptable. It has now been found that the softening performance of amine containing fabric softener compositions can significantly be improved by incorporation of non-saponified fatty acid materials in the composition. Furthermore compositions of the invention have the advantage that they can easily be prepared and that they are of acceptable stability and viscosity. Accordingly the present invention relates to a fabric conditioning composition comprising an amine softener material; a non-saponified fatty acid material; and a buffer acid; the pH of the composition being less than 6.5. The term "amine" as used herein can refer to any amine material which can be used for the softening of fabrics, for example one or more amines of the following formula can be used: (i) amines of formula wherein R₁₅, R₁₆ and R₁₇ are defined as below; (ii) amines of formula wherein R₁₈, R₁₉, R₂₀ and R₂₁, m and n are defined as below. (iii) imidazolines of formula herein R₁₁, R₁₂ and R₁₄ are defined as below. (iv) condensation products formed from the reaction of fatty acids with a polyamine selected from the group consisting of hydroxy alkylalkylenediamines and dialkylenetriamines and mixtures thereof. Suitable materials are disclosed in European Patent Application 199 382 (Procter and Gamble), incorporated herein by reference. When the amine is of the formula I above, R₁₅ is a C₆ to C₂₄, hydrocarbyl group, R₁₆ is a C₁ to C₂₄ hydrocarbyl group and R₁₇ is a C₁ to C₁₀ hydrocarbyl group. Suitable amines include those materials wherein both R₁₅ and R₁₆ are C₆-C₂₀ alkyl with C₁₆-C₁₈ being most preferred and with R₁₇ as C₁₋₃ alkyl, or R₁₅ is an alkyl or alkenyl group with at least 22 carbon atoms and R₁₆ and R₁₂ are C₁₋₃ alkyl. When the amine is of formula II above, R₁₈ is a C₆ to C₂₄ hydrocarbyl group, R₁₉ is an alkoxylated group of formula -(CH₂CH₂O) y H, where y is within the range from 0 to 6, R₂₀ is an alkoxylated group of formula -(CH₂CH₂O) z H where z is within the range from 0 to 6 and m is an integer within the rnage from 0 to 6, and is preferably 3. When m is 0, it is preferred that R₁₈ is a C₁₆ to C₂₂ alkyl and that the sum total of z and y is within the range from 1 to 6, more preferably 1 to 3. When m is 1, it is preferred that R₁₈ is a C₁₆ to C₂₂ alkyl and that the sum total of x and y and z is within the range from 3 to 10. Representative commercially available materials of this class include Ethomeen (ex Armour) and Ethoduomeen (ex Armour). When the amine is of formula (III), R₁₁ is a hydrocarbyl group containing from 8 to 25 carbon atoms, R₁₄ is an hydrocarbyl group containing from 8 to 25 carbon atoms and R₁₂ is hydrogen or an hydrocarbyl containing from 1 to 4 carbon atoms and A⁻ is an anion, preferably a halide, methosulfate or ethosulfate. It is necessary that the amines be protonated for use in the fabric conditioning compositions of the invention. Acids with a buffer action are used to effect protonation and diminish the unwanted effects of anionic actives carried over from the main wash. Suitable buffer acids for use in the invention are citric acid, phosphoric acid, hydrochloric acid, sulphuric acid and benzoic acid. Preferred buffer acids are citric and phosphoric acids. The amine and buffer acid may be used in a molar ratio of from 5:1 to 1:10 amine to buffer acid but preferably the buffer acid is used in molar excess to the amine so that molar ratios of from 1:1 to 1:10 are preferred. Preferred amine materials are materials of formula (i), which comprise two long alkyl groups and one short alkyl group. Especially preferred is the use of dihardened tallow methyl amine, as marketed under the tradename ARMEEN M2HT (Atlas). In this specification the expression hydrocarbyl group refers to alkyl or alkenyl groups optionally substituted or interrupted by functional groups such as -OH, -O-, -CONH, -COO-, etc. The level of amine softener materials is preferably more than 1% by weight of the composition, more preferred more than 2%, most preferred more than 3%. Preferably the level of amine softener materials will not exceed 70% by weight of the composition, more preferred the level is less than 30%, especially preferred are compositions comprising from 3 to 20% by weight of amine softener materials. The non-saponified fatty acid material can be any mono-, di- or tri-carboxylic acid comprising an alkyl or alkenyl chain having from 8 to 28 carbon atoms. Preferred fatty acid materials may be represented by the formula: R₁COOR₂ wherein R₁ is a straight or branched alkyl or alkenyl chain having from 8 to 28 carbon atoms, and wherein R₂ is hydrogen. Preferred is the use of free fatty acids having a chain length of from 12 to 18, such as oleic acid, lauric acid, tallow fatty acid etc. Preferably the level of fatty acid material is more than 0.1% by weight of the composition, more preferred more than 0.2%, especially preferred are systems comprising more than 0.5% of fatty acid material. The level of fatty acid material will usually not exceed 50% by weight of the composition, more preferred the level of fatty acid material is less than 30%, typically from 0.5 to 10% by weight of the composition. The weight ratio of amine softening material to fatty acid material is preferably from 10:1 to 1:10, more preferred from 9:1 to 1:1, most preferred from 7:1 to 3:1. Surprisingly it has been found that compositions according to the invention can be further improved by incorporating therein a nonionic material of specific HLB value. Preferred nonionic materials for use in compositions of the invention have an HLB value in the range from 7.0 to 21.0, more preferred from 9.0 to 19.0, especially preferred from 10.0 to 18.0. It is believed that the nonionic materials may contribute in two ways to a quality improvement of the compositions of the invention: firstly the softening performance may be enhanced and secondly the viscosity of the product is decreased. It has also been found that nonionic materials of relative low HLB are especially useful for use in compositions of low active level, while compositions of high active level preferably comprise nonionic materials of relative high HLB. Preferably compositions, wherein the total level of amine and fatty acid material is from 5 to 10% by weight of the composition comprise a nonionic material having an HLB of between 9.0 and 13.0; compositions wherein the active level is from 10-15% by weight of the composition, preferably comprise a nonionic material of HLB between 11.5 and 16.5. An active level of 15-20% by weight corresponds to a preferred HLB value of from 14.0-19.0; compositions of active level between 20 and 25% preferably comprise a nonionic material of HLB of between 16.5 and 21.0. Preferred nonionic materials are alkoxylated fatty alcohols, preferably containing a fatty alcohol having from 8-28 carbon atoms, said alcohol being ethoxylated with from 2-50, preferably from 4-40 ethoxy-groups. Preferably the level of nonionic material is more than 0.1% by weight of the composition, more preferred more than 0.2%, especially preferred are systems comprising more than 0.5% of nonionic material. The level of nonionic material will usually not exceed 50% by weight of the composition, more preferred the level of nonionic material is less than 30%, typically from 0.5 to 10% by weight of the composition. Surprisingly it has been found that a further improvement in the softening performance can be obtained by incorporating a fatty acid ester material of a short chain polyol into the fabric conditioning composition of the invention. The ester materials for incorporation into a product of the present invention is preferably a mono-di- or triester of a C₁₋₅ polyol with a fatty acid material. preferably the polyol is ethylene glycol, glycerol or propylene glycol. Preferred fatty acid materials comprise an alkyl or alkenyl chain of from 8 to 28 carbon atoms, preferably from 12 to 20 carbon atoms. Especially suitable are fatty acid materials selected from lauric acid, tallow fatty acid, hardened tallow fatty acid, coconut fatty acid, stearic acid or mixtures thereof. Particularly preferred are the di-esters of fatty acid materials and polyols. Especially the di-fatty acid of ethylene glycol. Specifically preferred is the use of ethylene glycol distearate. Preferably the level of fatty ester materials is more than 0.1% by weight of the composition, more preferred more than 0.5%. Preferably the level of fatty ester material does not exceed the 30%, more preferably the level is less than 20%, most preferred between 0.7 and 10%. Compositions of the present invention may comprise in addition to the above mentioned amine, fatty acid and optional materials one or more other softener materials selected from cationic, amphoteric and nonionic softening materials. Suitable materials are for example described in EP 239 910 (P&G), US 3 915 865 (STEPAN) and US 4 137 180 (Lever Brothers). Preferably the weight ratio of these additional softening materials to the total of the two above mentioned essential softening materials is less than 3:1, more preferred less than 1:1, especially preferred less than 0.5:1. Compositions of the present invention may take a variety of forms such as liquids, pastes and gels. Preferably compositions of the present invention are liquids, comprising an aqueous phase. Preferably the water level in such aqueous liquids is from 97 to 20% by weight of the composition, more preferred from 95 to 70%. The composition can also contain one or more optional ingredients selected from non-aqueous solvents such as C₁-C₄ alkanols and polyhydric alcohols, rewetting agents, viscosity modifiers such as electrolytes, for example calcium chloride, antigelling agents, perfumes, perfume carriers, fluorescers, colourants, hydrotropes, antifoaming agents, antiredeposition agents, enzymes, optical brightening agents, opacifiers, stabilisers such as guar gum and polyethylene glycol, emulsifiers, anti-shrinking agents, anti-wrinkle agents, fabric crisping agents, anti-spotting agents, soil-release agents, germicides, linear or branched silicones, fungicides, anti-oxidants, anti-corrosion agents, preservatives such as Proxel, ascoric acid, Bronopol (Trade Mark), a commercially available form of 2-bromo-2-nitropropane-1,3-diol, dyes, bleaches and bleach precursors, drape imparting agents, antistatic agents and ironing aids. These optional ingredients, if added, preferably are present at levels up to 5% by weight of the composition. The liquid compositions according to the inventions may be prepared by a variety of methods. One suitable method is to form a molten mixture of the amine materials and the fatty acid materials eventually in combination with other softening materials, and adding this premix to water under stirring to form a dispersion and thereafter adding any optional ingredients. Compositions of the present invention have a pH of less than 6.5, more preferred less than 5.0, especially preferred are compositions which have a pH of between 2.0 and 4.0, especially from 3.0 to 4.0. In use, the fabric conditioning composition of the invention may be added to a large volume of water to form a liquor with which the fabrics to be treated are contacted. Generally, the total concentration of the amine compound and the fatty acid ester compound in this liquor will be between about 30ppm and 1000ppm. The weight ratio of the fabrics to liquor will generally be between 1:1 to 1:10. Surprisingly it has also been found that a decrease in the pH in the rinse liquor provides a further increase in softening performance of compositions of the invention. The pH of a rinse liquor comprising the amine and fatty acid materials in a total concentration of from 30 to 1000ppm (preferably around 200ppm) should be less than 6.5, more preferred less than 6.0. This low pH is preferably effected by acidifying ingredients such as phosphoric or citric acid which are already present in the fabric softener; if necessary, however, separate ingredients may be added to the rinse water for lowering the pH. The invention will be further illustrated by means of the following examples. EXAMPLE 1 The following compositions were made by pre-heating a mixture of amine, fatty acid and nonionic and dispersing the mixture in water. In all the examples the amine materials were protonated with an equimolar amount of citric acid. The compositions were tested by adding 2g of the compositions to 1 litre of water (11 FH) and rinsing therein 3 pieces of terry towelling (total weight 48g) for 5 minutes at 100 rpm. The pieces of cloth were line dried and assessed for softness by a trained panel of 8 persons. A higher score indicates a better softening. INGREDIENT (%wt) A B C Armeen M2HT 6.4 6.0 7.5 Fatty acid 1.1 1.5 -- nonionic 1.1 1.5 -- softening score 0.25 0.48 -0.36 These results clearly show an increase in performance for softening compositions which comprise amines in combination with fatty acid materials. EXAMPLE 2 Composition D was prepared as in example 1 and compared to a commercially available rinse conditioner containing a conventional dihardened tallow dimethyl ammonium chloride softener material. A 2.5kg load of terry towelling was washed at 60°C in an AEG Lavamat 570 with water of 26 FH in the presence of 100g Persil Automatic (UK). To the last rinse cycle of the washing process an amount of softener material was added corresponding to the indicated levels of active material. The cloths were line dried and assessed for softness by a trained panel of 8 persons; a higher softness indicates a better softening. INGREDIENT (%wt) D E Armeen M2HT 6.0 -- fatty acid 1.5 -- nonionic 1.5 -- DTDMAC -- 4.5 grms active 4 7 10 4 7 10 softening score 2.7 5.1 5.2 4.0 4.8 5.3 This example shows that, surprisingly amine containing softening compositions can be formulated which are almost as effective as commercial available softener materials comprising environmentally less preferred quaternary ammonium materials. EXAMPLE 3 Compositions F and G were prepared as in example 1, and compared to a commercially available softener material on the basis of dihardened tallow dimethyl ammonium chloride. A 2.5kg load of desized terry towelling cloths was washed at 60°C in a Siemens washing machine with water of 26 FH in the presence of 100g of Persil Automatic (UK). 100g of the compositions F-H was added to the last rinse cycle, the cloths were line dried and assessed for softness by a trained panel of 8 members, a higher softening score indicates a better softening. INGREDIENT (%wt) F G H Armeen M2HT 6.0 5.2 -- fatty acid 1.5 1.3 -- nonionic 1.5 1.3 -- EGDS -- 1.0 -- citric acid 1.0 1.0 -- DTDMAC -- -- 4.5 softening score 0.01 0.65 -0.87 These results clearly illustrate that the addition of a polyol ester further increases the softening performance of compositions of the invention. EXAMPLE 4 The following compositions were prepared as in example 1 and tested as in example 3. INGREDIENT (%wt) I J K Armeen M2HT 6.0 6.0 6.0 Fatty acid ) 1.5 1.5 1.5 nonionic 1.5 1.5 1.5 citric acid 3.0 4.25 8.0 pH (in rinse) 6.5 5.9 4.9 softening score -0.38 0.12 0.33 This example illustrates that by lowering the pH in the rinse water, a better softening can be obtained. EXAMPLE 5 The following compositions were prepared as in example 1. The viscosity of the products was measured at 110 s-1. INGREDIENT (%wt) L M N O Armeen M2HT 12.0 12.0 13.0 13.0 fatty acid 3.0 3.0 2.0 2.0 nonionic 1 3.0 -- 2.0 -- nonionic 2 -- 3.0 -- 2.0 CaCl₂ 0.01 0.01 0.01 0.01 viscosity MPa.s 40 275 25 275 These results illustrate that for obtaining products of low viscosity, preferably at high active levels a highly ethoxylated nonionic of relative high HLB is used.

Claims: A liquid fabric softening composition in the form of a dispersion in aqueous medium comprising: (i) an amine softening material; (ii) a non-saponified fatty acid material; and (iii) a buffer acid; the pH of the composition being less than 6.5. A liquid fabric softening composition as claimed in claim 1 wherein the amine softening material is of the formula: wherein R₁₅ is a C₆ to C₂₄ hydrocarbyl group, R₁₆ is a C₁ to C₂₄ hydrocarbyl group, and R₁₇ is a C₁ to C₁₀ hydrocarbyl group. A liquid fabric softening composition as claimed in claim 1 or claim 2 wherein the composition further comprises a nonionic material of HLB between 7.0 and 21.0. A liquid fabric softening composition as claimed in any preceding claim wherein the composition further comprises an ester of a fatty acid and a short chain polyol. A liquid fabric softening composition as claimed in any preceding claim comprising less than 30% by weight of the non-saponified fatty acid material. A liquid fabric softening composition in the form of a dispersion in aqueous medium comprising: (i) from 3 to 20% by weight of an amine softening material; (ii) from 0.5% to 10% by weight of a non-saponified fatty acid material; and (iii) a buffer acid; the molar ratio of the amine softening material to the buffer acid being from 5:1 to 1:10 and the pH of the composition being less than 6.5. A liquid fabric softening composition as claimed in claim 6 which further comprises a nonionic material of HLB between 7.0 and 10.0. A liquid fabric softening composition as claimed in any preceding claim providing upon dilution in water to a total concentration of amine materials and fatty acid materials of between 30 and 1000ppm a liquor having a pH of less than 6.5.

Inventors: TANDELA SABINE DAGMER
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1990
Main classification: C11D1
IPC codes: C11D3, D06M13, C11D1