Fabric softening composition

Abstract: An aqueous fabric conditioning composition comprising a fabric softener and a polymeric thickening material, said material comprising molecules with a hydrophilic backbone and at least two hydrophobic groups per molecule attached to the hydrophilic backbone, with the proviso that the polymeric material is not a hydrophobically modified nonionic cellulose ether.

Description: This invention relates to a fabric softening composition and to a process for treating fabrics therewith. Fabric softening compositions are used in textile finishing and laundering processes to impart properties such as softness and a pleasant feel or "handle" to fabrics, and are used particularly in the rinse stage of the laundering process immediately after the laundry articles have been washed in a washing machine. A large number of proposals has been made for the formulation of fabric softening compositions, most of these involving the use of an aqueous dispersion of a cationic surfactant, for instance a quaternary ammonium salt or an imidazolinium salt, as the active component or as part of it. It is known from GB-A-2039556 that fabric softening compositions can be formulated to comprise a dispersion of cationic surfactant together with free fatty acid which functions as a nonionic surfactant. EP-A-0,299,787 relates to a high concentration cloth-softening composition which includes (a) a quaternary ammonium softener and (b) a viscosity control additive which is either (i) a polyether of a specific 5 type, or derivative thereof or (ii) a polymer or copolymer of a cationic surfactant monomer of a particular type. EP-A-0,095,580 describes polyether derivatives and their method of preparation, the derivatives being of use as dispersants in concentrated textile softening compositions based on quaternary ammonium salts. The above compositions based on dispersions of cationic surfactants are non-Newtonian in character. In compositions intended for use by consumers in the home the viscosity (or strictly the apparent viscosity) of the composition is an important factor in its acceptability to the consumer, the more viscous compositions being perceived as being of higher quality than the more mobile ones. Manufacturers therefore attempt to produce a product which is as viscous as possible without being so viscous that problems are created elsewhere, such as in pouring or dispensing characteristics. In compositions intended for automated dispensing in washing machines, a low but tightly controlled viscosity is desirable, which again is difficult to achieve if the composition behaves unpredictably during manufacture and subsequent ageing. EP-51983 discloses a process for the manufacture of a shear-thinning fabric softening composition, with good control of final viscosity, comprising the steps of sequentially or simultaneously: (i) forming an aqueous dispersion of a cationic surfactant, having a viscosity less than the final viscosity; and (ii) thickening the composition to the final viscosity with a nonionic or weakly anionic polymeric thickener. The thickener is selected from guar gum, polyvinylacetate, polyacrylamide, or a mixture of guar gum and xanthan gum containing no more than 10% by weight of xanthan gum. The polyacrylamides which are specifically referred to are the less anionic polyacrylamides. Quaternised guar gum was stated to be unsuitable. The essence of the process of EP-51983 is to form a dispersion which is less viscous than is desired, and then thicken it with a polymeric thickener. We have now found that a further class of polymeric materials is especially suitable as a thickener for fabric conditioning compositions. These materials provide dispersions the viscosity of which is relatively stable, and which do not bring with them any disadvantage which would make the product unsatisfactory for treating fabrics. These thickeners are polymeric substances comprising a hydrophilic backbone and at least two hydrophobic moieties per molecule. Accordingly the present invention relates to an aqueous fabric conditioning composition comprising a fabric softener and between 0.008 and 0.80% by weight of a polymeric material, said material comprising a hydrophobically modified nonionic polymer having a hydrophilic backbone, a significant number of the molecules thereof having at least two hydrophobic groups per molecule attached to the hydrophilic backbone, with the proviso that the polymeric material is not a hydrophobically modified nonionic cellulose ether, characterised in that the hydrophobic groups constitute between 0.5 and 2.0% by weight of the polymeric material and that the combination of the softener and the polymeric material has a higher viscosity than that of the softener alone. For the purpose of this invention only combinations of softener materials and polymers are claimed which have a higher viscosity in the presence of the polymer than in the absence of the polymer. It is believed that only polymeric molecules having at least two hydrophobic moieties contribute to the thickening effect. For practical purposes, however, generally a reaction mixture of polymeric molecules will be used, in that case it is not necessary that in such a mixture the molecules contain on average two hydrophobic moieties; satisfactory results can also be obtained when the average is less than two, provided that a significant part of the molecules comprise two or more hydrophobic moieties. It is however preferred that polymeric reaction mixtures are used which comprise on average two or more hydrophobic moieties per molecule. Preferably the number of hydrophobic groups attached to the hydrophilic backbone is relatively small. Thus, the hydrophobic groups constitute between 0.5 and 2% by weight of the polymer. These relatively small numbers of hydrophobic groups ensure that the molecules remain relatively water soluble. Preferred polymeric thickeners according to the invention have a solubility in water at 25°C of more than 0,01% by weight, preferably more than 0.5% by weight, most preferred between 0.5 and 25% by weight. Preferred hydrophobic groups are linear or branched alkyl or alkenyl groups, preferably having a chain length of less than 40, more preferably between 8 and 24 carbon atoms. The polymeric thickeners for use in fabric conditioners according to the invention have a nonionic hydrophilic backbone , ie they are hydrophobically modified nonionic polymers. Preferred hydrophobically modified nonionic polymers are based on polyoxyalkylene or polyvinylalcohol hydrophilic backbones, to which a small number of alkyl groups have been attached. Examples of these materials are: (i) copolymers of ethylene oxide and/or propylene oxide with small amounts of C₈-C₂₄ side chains, for instance having the basic formula: (ii) Hydrophobically modified poly (ethylene oxide and/or propylene oxide/urethanes) for instance of the following formula: (iii) alkyl substituted poly (vinyl) alcohols, for instance of the following formula: Wherein: p = 1 to 4 preferably 1 or 2 n+m = greater than 10 m = If p is greater than 1, m is such that the group involved constitutes less than 50 mole %, preferably less than 25 mole % of the polymer. R₁ = a C₈-C₂₄ linear or branched alkyl or alkenyl R₂ = hydrogen or a C₈-C₂₄ linear or branched alkyl or alkenyl R₃ = a minimum of two R₁ groups which can be substituted at any CH₂ group along the polymer backbone. Hydrophobically modified poly (ethylene oxide and/or propylene oxide/urethanes) according to formula (ii) are marketed by UNION CARBIDE under the UCAR SCT trademark for the thickening of latex systems and generally have a molecular weight in the region of 40,000. Up till now it has not been recognised that these materials can advantageously be incorporated in fabric conditioning systems which are of a totally different nature than the latex systems in which the materials have been incorporated up till now. Also a surprising aspect of the present invention is that the level of thickener material, necessary to obtain the desired thickening effect is far less when using a polymeric material as now claimed for use in softener systems than by using other thickener materials which have up till now been used for the thickening of fabric conditioning compositions. Depending upon the viscosity required, the polymeric material will be present in the composition of the invention in an amount of from 0.008 to 0.80% by weight, preferably from 0.01 to 0.30% by weight of the composition. The preferred molecular weight of the thickener materials to be used is preferably above 15,000 more preferred from 20,000 to 1,000,000 more preferred from 25,000 to 100,000, especially preferred from 30,000 to 70,000. The fabric softener for use in the fabric conditioning composition according to the invention can be any fabric substantive cationic, nonionic or amphoteric material suitable for softening fabrics. Preferably the softening material is a cationic material which is water-insoluble in that these materials have a solubility in water at pH 2.5 and 20°C of less than 10 g/l. Highly preferred materials are cationic quaternary ammonium salts having two C12-24 hydrocarbyl chains. Well-known species of substantially water-insoluble quaternary ammonium compounds have the formula wherein R₁ and R₂ represent hydrocarbyl groups from about 12 to about 24 carbon atoms; R₃ and R₄ represent hydrocarbyl groups containing from 1 to about 4 carbon atoms; and X is an anion, preferably selected from halide, methyl sulfate and ethyl sulfate radicals. Representative examples of these quaternary softeners include ditallow ammonium chloride; ditallowdimethyl ammonium methyl sulfate; dihexadecyl dimethyl ammonium chloride; di(hydrogenated tallow) dimethyl ammonium methyl sulfate; dihexadecyl diethyl ammonium chloride; di(coconut) dimethyl ammonium chloride. Ditallow dimethyl ammonium chloride, di(hydrogenated tallow) dimethyl ammonium chloride, di(coconut) dimethyl ammonium chloride and di(coconut) dimethyl ammonium methosulfate are preferred. Other preferred cationic compounds include those materials as disclosed in EP 239 910 (P&G). 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. Other preferred materials are the materials of the formula R₅ being tallow, which is available from Stepan under the tradename Stepantex VRH 90 and where R₈, R₉ and R₁₀ are each alkyl or hydroxyalkyl groups containing from 1 to 4 carbon atoms, or a benzyl group. R₆ and R₇ are each an alkyl or alkenyl chain containing from 11 to 23 carbon atoms, and X⁻ is a water soluble anion. Another class of preferred water-insoluble cationic materials are the hydrocarbylimidazolinium salts believed to have the formula: wherein R₁₃ is a hydrocarbyl group containing from 1 to 4, preferably 1 or 2 carbon atoms, 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. Preferred imidazolinium salts include 1-methyl-1-(tallowylamido-) ethyl -2-tallowyl- 4,5,-dihydro imidazolinium methosulfate and 1-methyl-1-(palmitoylamido) ethyl -2-octadecyl-4,5- dihydroimidazolinium chloride. Other useful imidazolinium materials are 2-heptadecyl-1-methyl-1-(2-stearylamido)-ethyl-imidazolinium chloride and 2-lauryl-1-hydroxyethyl-1-oleyl-imidazolinium chloride. Also suitable herein are the imidazolinium fabric softening components of US patent No. 4 127 489. Preferably the level of softening material in a composition according to the invention is from 1-75 weight %, preferably from 2-60% by weight more preferred from 2 to 15% by weight of the compositions. The compositions may also contain preferably, in addition to the cationic fabric softener, other non-cationic fabric softeners, such as nonionic or amphoteric fabric softeners. Suitable nonionic fabric softeners include glycerol esters, such as glycerol monostearate, fatty alcohols, such as stearyl alcohol, alkoxylated fatty alcohols C₉-C₂₄ fatty acids and lanolin and derivatives thereof. Suitable materials are disclosed in EP-A-0,088,520 (Unilever NV), EP-A-0,122,141 (Unilever PLC/NV) and EP-A-0,079,746 (Procter and Gamble). Typically such materials are included at a level within the range of from 1-75%, preferably from 2-60%, more preferred from 2 to 15% by weight of the composition. The compositions according to the invention may also contain preferably in addition to cationic fabric softening agents, one or more amines. The term "amine" as used herein can refer to (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 wherein R₁₁, R₁₂ and R₁₄ are defined as above. (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 EP-A-0 199 382 (Procter and Gamble). 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 from which the quaternary ammonium compounds disclosed above are derived, in which R₁₅ is R₁, R₁₆ is R₂ and R₁₇ is R₃. Preferably, the amine is such that 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. Preferably these amines are protonated with hydrochloric acid, orthophosphoric acid (OPA), C₁₋₅ carboxylic acids or any other similar acids, for use in the fabric conditioning compositions of the invention. 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 O to 6, R₂₀ is an alkoxylated group of formula -(CH₂CH₂O) z H where z is within the range from 0 to 6, and is preferably 3. When m is O, 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 (Trade Mark) (ex Armour) and Ethodoumeen (Trade MarK) (ex Armour). Preferably the amines of type (ii) or (iii) are also protonated for use in the fabric conditioning compositions of the invention. When the amine is of type (iv) given above, a particularly preferred material is where R₂₂ and R₂₃ are divalent alkenyl chains having from 1 to 3 carbon atoms, and R₂₄ is an acyclic aliphatic hydrocarbon chain having from 15 to 21 carbon atoms. A commercially available material of this class is Ceranine HC39 (Trade Mark) (ex Sandoz). Mixtures of the amines may also be used. When present, amine materials are typically included at a level within the range of from 1-75%, preferably 2-60% more preferred 2 to 15% by weight of the composition. Optionally compositions according to the invention may also comprise one or more amine oxides of the formula: wherein R₂₅ is a hydrocarbyl group containing 8 to 24, preferably 10 to 22 carbon atoms, R₂₆ is an alkyl group containing 1 to 4 carbon atoms or a group of formula-(CH₂CH₂O) v H, v is an integer from 1 to 6, R₂₇ is either R₂₅ or R₂₆, R₂₈ is R₂₆, r is 0 of 1 and q is 3. The invention is particularly advantageous if the amine oxide contains two alkyl or alkenyl groups each with at least 14 carbons atoms, such as dihardened tallow methyl amine oxide, or one alkyl or alkenyl group with at least 22 carbon atoms. When present such materials are typically included at a level of from 1-75, preferably 2-60 more preferred 2 to 15% by weight of the composition. Preferably, the compositions of the invention contain substantially no anionic material, in particular no anionic surface active material. If such materials are present, the weight ratio of the cationic fabric softening agent to the anionic material should preferably be more than 5:1. The composition can also contain one or more optional ingredients selected from non-aqueous solvents such as C₁-C₄ alkanols and polyhydric alcohols, pH buffering agents such as strong or weak acids e.g. HCl, H₂SO₄, phosphoric, benzoic or citric acid (the pH of the compositions are preferably less than 5.0), 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 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, are each present at levels up to 5% by weight of the composition. The pH of the composition is preferably 5 or below, or adjusted thereto. Fabric conditioning compositions according to the invention may be prepared by any conventional method for the preparation of dispersed softener systems. A well-known method for the preparation of such dispersed systems involves the preheating of the active ingredients, followed by formation of a pre-dispersion of this material in water of elevated temperature, and diluting said systems to ambient temperature systems. The invention also provides a process for the manufacture of a shear-thinning fabric conditioner, comprising the steps of sequentially (a) forming an aqueous dispersion of a softener having a viscosity of less than the final viscosity; and (b) thickening the composition to a final viscosity by including between 0.008 and 0.80% by weight of the final composition of a polymeric material comprising a hydrophobically modified nonionic polymer having a hydrophilic backbone, a significant number of the molecules thereof having at least two hydrophobic groups per molecule attached to the hydrophilic backbone, the polymeric material not being a hydrophobically modified nonionic cellulose ether, the hydrophobic groups constituting between 0.5 and 2.0% by weight of the polymeric material. The final viscosity of the composition will be chosen in accordance with the end-use desired, but will generally be between 10 and 200 mPas, preferably between 20 and 120 mPas at 25°C and 106 s-1. 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 concentration of the fabric softener, in this liquor will be between about 10 ppm and 1,000 ppm. The weight ratio of the fabrics to liquor will generally be between 40:1 and 4:1. The invention will be further illustrated by means of the following examples. EXAMPLE I Basic fabric conditioner compositions of the following compositions were prepared by the following process (i) charge water into a mixing vessel, heat to 65°C and add dye (ii) heat cationic/nonionic active materials to 70°C (iii)add heated active materials to water while stirring at 250 rpm (iv) cool the product and add the appropriate amount of thickener (v) add perfume and formalin. Composition A B Ingredients % by weight % by weight Arquad 2HT (Trade Mark) 4.5 10.4 Pristerine 4916 (Trade Mark) (ex Unichema) -- 2.6 Preservative 0.02 0.02 Colouring 0.00055 0.00165 Phosphoric acid 0.03 0.04 Magnesium chloride -- 0.02 Perfume 0.21 0.55 Water balance Composition D Ingredient % by weight Arquad 2HT 3.43 Pristerine 4916 0.51 Formaldehyde 0.08 Colouring 0.0018 Perfume 0.25 Silicone (b) 0.029 Water balance The viscosity of the products at 25°C and 106 s-1 were measured in the presence and in the absence of 0.03% by weight of a polymeric thickener UCAR SCT 215 (Trade Mark) (ex Union Carbide), added in the form of a 25% solution as supplied. The results were the following viscosity in mPas Composition o% UCAR 0.03% UCAR A 28 300 B 33 231 C 38.5 55.5 D 35 43 EXAMPLE 2 The viscosity of compositions D of Example I was measured after addition of various levels of UCAR SCT-215 or Acrysol RM-825 (Trade Mark) (polyurethane polymer ex Rohm and Haas added in the form of a 15% solution as supplied). Viscosities were measured in mPas at 25°C at 110 s-1. The results were the following: UCAR SCT-215 Weight % polymer viscosity (mPas 110s-1) 0 33 0.02 38 0.04 63 0.06 92 0.10 145 ACRYSOL RM-825 Weight % polymer viscosity (mPas 110s-1) 0 34 0.02 34 0.04 43 0.06 52 0.10 77

Claims: An aqueous fabric conditioning composition comprising a fabric softener and between 0.008 and 0.80% by weight of a polymeric material, said material comprising a hydrophobically modified nonionic polymer having a hydrophilic backbone, a significant number of the molecules thereof having at least two hydrophobic groups per molecule attached to the hydrophilic backbone, with the proviso that the polymeric material is not a hydrophobically modified nonionic cellulose ether, characterised in that the hydrophobic groups constitute between 0.5 and 2.0% by weight of the polymeric material and in that the combination of the softener and the polymeric material has a higher viscosity than that of the softener alone. A fabric conditioning composition according to claim 1, wherein the polymeric thickening material has a molecular weight of more than 15,000. A fabric conditioning composition according to claim 2, characterised in that the molecular weight of the polymeric material is between 25,000 and 100,000. A fabric conditioning composition according to one or more of the preceding claims, comprising from 0.01 to 0.30% by weight of the polymeric material. A fabric conditioning composition according to one or more of the preceding claims, wherein the polymeric material is selected from: (i) copolymers of ethylene oxide and/or propylene oxide with small amounts of C₈-C₂₄ side chains, for instance having the basic formula: (ii) Hydrophobically modified poly (ethylene oxide and/or propylene oxide/urethanes) for instance of the following formula: (iii) alkyl substituted poly (vinyl) alcohols, for instance of the following formula: Wherein: p = 1 to 4 preferably 1 or 2 n+m = greater than 10 m = If p is greater than 1, m is such that the group involved constitutes less than 50 mole %, preferably less than 25 mole % of the polymer R₁ = a C₈-C₂₄ linear or branched alkyl or alkenyl R₂ = hydrogen or a C₈-C₂₄ linear or branched alkyl or alkenyl R₃ = a minimum of two R₁ groups which can be substituted at any CH₂ group along the polymer backbone. A method for the treatment of fabrics wherein fabrics are contacted with an aqueous liquor comprising a fabric conditioning composition according to one or more of the preceding claims, the concentration of fabric softener in the liquor being between 10 and 1,000 ppm. A process for the manufacture of a shear-thinning fabric conditioner, comprising the steps of sequentially (a) forming an aqueous dispersion of a softener having a viscosity of less than the final viscosity; and (b) thickening the composition to a final viscosity by including between 0.008 and 0.80% by weight of the final composition of a polymeric material comprising a hydrophobically modified nonionic polymer having a hydrophilic backbone, a significant number of the molecules thereof having at least two hydrophobic groups per molecuie attached to the hydrophilic backbone, the polymeric material not being a hydrophobically modified nonionic cellulose ether, the hydrophobic groups constituting between 0.5 and 2.0% by weight of the polymeric material.

Inventors: BUTTERWORTH ROBERT MICHAEL, SAUNDERS KENWYN DAVID, BUTTERWORTH, ROBERT MICHAEL, SAUNDERS, KENWYN DAVID
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1990
Main classification: C11D3
IPC codes: C11D1, C11D7, D06M13, C11D3, D06M15