Fabric softening composition

Abstract: A fabric softening composition is provided which comprises: (i) an amphoteric fabric softening material; (ii) a nonionic cellulose ether having a gel point of less than 58°C, an HLB of between 3.1 and 4.3, said cellulose ether being substituted with C₁₋₃ alkyl and/or hydroxyalkyl groups; said composition preferably having a pH of between 1.5 and 6.0 at a concentration of 1 g/l of amphoteric softening material in water at 25°C.

Description: FABRIC SOFTENING COMPOSITION This invention relates to a fabric softening composition. In particular it relates to a fabric softening composition, which comprises an amphoteric material as active ingredient and which is intended for addition to the rinse or drying step of a fabric laundering process. British Patent Specification No. 1 260 584 (ARMOUR) discloses a method of softening fabrics by the use of a composition containing a quaternary ammonium compound and a tertiary amine oxide. The use of the amine oxide in addition to the quaternary ammonium compound leads to a number of advantages including improved performance on cotton in the presence of anionic surfactants, which can be carried over from the wash step in a fabric laundering process. Despite these advantages on cotton fabric softening compositions known in the art generally suffer from the disadvantage that they do not perform particularly well in the softening of fabrics which contain a substantial amount of wool. EP-A-0 269 939 describes the use of amphoteric detergent compounds to wash wool. Nonionic cellulose ethers are mentioned as one class of polymer which can also be included in the detergent composition. British Patent Specification GB 2 083 353 discloses certain detergent compositions for through the wash softening which optionally comprise ionic cellulose ethers. EP-A-0 276 999 discloses the use of nonionic cellulose ethers to improve the deposition of various softeners. The compositions of this reference are shown to improve the softening of terry towelling. It is an object of the present invention to provide a fabric softening composition which is especially suitable for the softening of wool in the rinse or drying step of a fabric laundering process. It has been found that the softening performance on wool can markedly be improved, when specific cellulose ether compounds are used in combination with an amine oxide material. It has also been found that the combination of these specific cellulose ethers with other amphoteric materials provides similar softening benefits to wool. Fabric conditioning compositions according to the present invention preferably have a pH of between 1.5 and 6.0 at a concentration of 1g/1 of amphoteric softening material in water at 25°C. The specific cellulose ethers useful in compositions of the present invention are low gel point cellulose ethers having an HLB value of between 3.1 and 4.3, a gel point of less than 58°C and are substituted with C₁₋₃ alkyl and/or hydroxyalkyl groups. Accordingly the present invention relates to a fabric softening composition comprising: (i) an amphoteric fabric softening material selected from amphoteric or zwitterionic ammonium compounds having two long hydrocarbyl chains, each chain having from 8 to 25 carbon atoms, said softening material being capable of forming a particulate dispersion at a concentration of less than 1g/l at at least one temperature between 0°C and 100°C and having a solubility in water at pH2.5 at 20°C of less than 10g/l (ii) a nonionic cellulose ether having a gel point of less than 58°C, an HLB of between 3.1 and 4.3, said cellulose ether being substituted with C₁₋₃ alkyl and/or hydroxyalkyl groups; said composition preferably having a pH of between 1.5 and 6.0 at a concentration of 1 g/l of amphoteric softening material in water at 25°C. Preferably compositions of the invention are liquids comprising an aqueous base. The amphoteric fabric softening material for use in a composition according to the invention is preferably a fabric substantive amphoteric material. Preferably the amphoteric material forms a particulate dispersion at a concentration of less than 1g/l at at least one temperature between 10 and 90°C, more preferred between 20 and 80°C. Amphoteric or zwitterionic ammonium compounds for use in compositions according to the present invention have two long hydrocarbyl chains, each chain having 8-25 C-atoms, preferably 10-20 C-atoms, most preferably around 16 C-atoms. In this specification the expression hydrocarbyl chain refers to linear or branched alkyl or alkenyl chains optionally substituted or interrupted by functional groups such as -OH, -O-, -CONH-, or -COO-. Suitable amphoteric fabric substantive materials for use in a fabric treatment compositions according to the invention are for instance: I) Ampholytes of the following formula: II) Hydrocarbyl betaines of the following formula: III) Hydrocarbylamido betaines of the following formula: IV) Glycinates or propionates of the following formula: V) tertiary amine oxides of the following formula wherein: R₁ and R₂ are C₈₋₂₅ hydrocarbyl chains, R₃ is an hydrocarbylgroup containing 1-4 carbon atoms or a group -(CH₂CH₂O) n H, R₄, R₅, are -(CH₂) n -, which can be interrupted with -O-, -CONH-, -COO- etc, n is an integer from 1-6, X, Y are SO 3 - , SO 4 2- or COO-. The amphoteric fabric substantive materials are water insoluble and have a solubility in water at pH 2.5 at 20°C of less than 10 g/l. The HLB of the amphoteric fabric substantive material is preferably less than 10.0. Examples of amphoteric materials of the above groups are the following: Group i (1) R₁ and R₂ being tallow, R₄ being -(CH₂)₂-, X being -COO- (2) R₁ and R₂ being hardened tallow, R₃ being (CH₂)₂, X being -COO- (3) R₁ and R₂ being coco, R₄ being -(CH₂)₃-, X being SO₃- (4) R₁ and R₂ being stearyl, R₄ being -(CH₂)₃- X being SO 4 2- Group ii (5) R₁ and R₂ being tallow, R₃ being methyl, R₄ being -(CH₂)₂-, X being -COO- Group iii (6) R₁ and R₂ being tallow, R 4,5 being -(CH₂)₂₋, R₃ being methyl, X being -COO- (7) R₁ and R₂ being coco, R 4,5 being -(CH₂)₂₋, R₃ being methyl, X being SO₃- Group iv (8) R₁ and R₂ being hardened tallow, R₅ being -(CH₂)₂-, X being SO 4 2- Group v (9) R₁ and R₂ being hardened tallow, R₃ being methyl (10) R₁ and R₂ being tallow, R₃ being methyl (11) R₁ and R₂ being stearyl, R₃ being methyl (12) R₁ and R₂ being coco, R₃ being methyl (13) R₁ and R₂ being CH₃ (CH₂)₁₄ COO-, R₃ being ethyl (14) R₁ and R₃ being CH₃(CH₂)₁₂ COO(CH₂)₂₋, R₂ being methyl From the above listed materials, particularly the group V materials are preferred, especially those amine oxides containing two hydrocarbyl groups with at least 14C-atoms. The level of amphoteric fabric conditioning material in the composition is preferably at least 1% by weight of the composition, especially preferred from 1-75% by weight, generally from 2-25% by weight, especially preferred from 3-15% by weight of the composition. The cellulose ethers useful in the present invention are nonionic cellulose ethers, of which some or all of the three hydroxyl sites per anhydroglucose rings of the polymer have been substituted with a nonionic substituent group. Preferably the substituent groups are selected from the C2-C3 alkyl and C2-C3 mono- or polyhydric hydroxy alkyl groups, or combinations thereof. Especially the use of alkyl hydroxyalkyl cellulose ethers is preferred. Most preferred is the use of ethyl hydroxyethyl substituted cellulose ethers. The choice and percentage of substituent groups has a direct influence on the HLB value of the cellulose ether. A suitable method for determining the HLB value of cellulose ethers is the method as described for emulsifiers by J T Davies, 2nd Int Congress of Surface Activity 1957, I pp 426-439. This method has been adopted to derive a relative HLB ranking for cellulose ethers by summation of Davies's HLB assignments for substituent groups at the three available hydroxyl sites on the anhydroglucose ring of the polymer. The HLB assignments for the substituents groups include the following: The cellulose ethers useful herein are polymers. The gel point of polymers can be measured in a number of ways. In the present context the gel point is measured on a polymer solution prepared at 10 g/l concentration in deionised water by heating 50 ml solution placed in a beaker, with stirring, at a heating rate of approximately 5°C/minute. The temperature at which the solution clouds is the gel point of the cellulose ether being tested and is measured using a Sybron/Brinkmann colorimeter at 80% transmission/450 nm. Provided that the HLB and gel point of the polymer fall within the required ranges, the degree of substitution (DS) of the anhydroglucose ring may be any value up to the theoretical maximum value of 3, but is preferably from about 1.7-2.9, there being a maximum of 3 hydroxyl groups on each anhydroglucose unit in cellulose. The expression 'molar substitution' (MS) is sometimes also used in connection with these polymers and refers the number of hydroxylakyl substituents per anhydroglucose ring and may be more than 3 when the substituents themselves carry further substituents. The most highly preferred polymers have an average number of anhydroglucose units in the cellulose polymer, or weight average degree of polymerisation, from about 50 to about 1,200. For certain product forms, e.g. liquids, it may be desirable to include polymers of relatively low degree of polymerisation to obtain a satisfactory product viscosity. A number of cellulose ethers suitable for use in the present invention are commercially available, as follows: Trade Name Gel Point °C HLB (Davies) DS/MS alkyl/hydroxyalkyl BERMOCOLL CST035 35 3.40 ) 1.4 ethyl (ex Berol Nobel) ) 0.5 hydroxyethyl DVT 88 004 37 3.11 ) 1.5 ethyl (ex Berol Nobel) ) 1.0 hydroxyethyl TYLOSE MHB 1000 54 3.52 ) 2.0 methyl (ex Hoechst) ) 0.1 hydroxyethyl A number of other cellulose ethers are known from the prior art, but have been found to be unsuitable for use in the present invention. Thus, British Specification No. GB 2 038 353B (COLGATE-PALMOLIVE) discloses TYLOSE MH 300 (ex Hoechst) which has a gel point of 58°C and METHOCEL XD 8861 (ex Dow Chemical Company, now coded METHOCEL HB12M) which contains about 0.1 hydroxybutyl substituents per anhydroglucose ring, while Japanese Patent Specification No. 59-6293 (LION KK) discloses KLUCEL H (ex Hercules Chemical Corp) which has an HLB of about 4.4, METHOCEL K4M (ex Dow Chemical Company) which has a gel point of about 69°C, and NATROSOL 250H (ex Hercules Chemical Corp) which has an HLB of about 6.9. The amount of cellulose ether to be employed in compositions according to the invention is preferably from 0.05 to 5%, more preferably from 0.5 to 3% by weight of the composition. The ratio of amphoteric softening material to nonionic cellulose ether is preferably from 50:1 to 1:10 by weight, more preferably 20:1 to 1:5 most preferably 10:1 to 1:5. Preferred cellulose ethers for use in compositions of the present invention have an HLB of between 3.3. and 3.8 and a gel point of between 30 and 55°C. Especially preferred is the use of Bermocoll CST035. Compositions of the present invention have a pH of between 1.5 and 6.0 when adjusted to an amphoteric softener level of 1 g/l in water of 25°C, more preferred between 2.0 and 5.0. Compositions having a pH value above 6.0 or below 1.5 are less suitable for use in the rinse or drying step of a fabric washing process. Fabric conditioning compositions according to the present invention may in addition to the amphoteric softener material and the cellulose ether also comprise other fabric softener materials such as nonionic or cationic fabric softening materials. In this respect the use of cationic fabric softening materials is preferred, these materials tend to promote the degree of deposition of the amphoteric materials and the cellulose ether materials, therwith increasing the softening performance of the composition. Preferably the cationic fabric softener material for optional use in a composition according to the present invention is a cationic material which is water-insoluble in that the material has 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 dimethyl ammonium chloride; ditallow dimethyl 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 methosuldate are preferred. Suitable materials also include dialkyl ethoxyl methyl ammonium methosulphate based on soft fatty acid, dialkyl ethoxyl methyl ammonium methosulphate based on hard fatty acid, and a material in which R₃ and R₄ represent methyl, R₁ is C₁₃₋₁₅, R₂ is CH₂CH₂OCOR, where R is stearyl , and X is methosulphate. Ditallow dimethyl ammonium chloride, di(hydrogenated tallow alkyl) dimethyl ammonium chloride, di(coconut alkyl) dimethyl ammonium chloride and di(coconut alkyl) dimethyl ammonium methosulfate are preferred. Other preferred cationic compounds include those materials as disclosed in EP-A-239, 910 (P&G) . Other preferred materials are the materials of 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. These materials and their method of preparation are described in US-A-4 137 180 (LEVER BROTHERS). 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- dihydro-imidazolinium chloride. Other useful imidazolinium materials are s-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. Representative commercially available materials of the above classes are the quaternary ammonium compounds Arquad 2HT (ex AKZO); Noramium M2SH (ex CEKA); Aliquat-2HT (Trade Mark of General Mills Inc), Stepantex Q185 (ex Stepan); Stepantex VP85 (ex Stepan); Stepantex VRH90 (ex Stepan); Synprolam FS (ex ICI) and the imidazolinium compounds Varisoft 475 (Trade Mark of Sherex Company, Columbus Ohio) and Rewoquat W7500 (Trade Mark of REWO). The compositions according to the invention may also possibly in addition to the 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 and are defined as below; (ii) amines of formula wherein R₁₈, 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 European Patent Application 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 us R 15y us 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 R 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, 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 range 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). 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 carbons 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 (ex Sandoz). Especially preferred is a composition comprising in addition to the amphoteric softener material and the cellulose ether both a cationic fabric softening material and an amine. Such compositions preferably comprise an aqueous base and: from 1 to 15% by weight of the amphoteric softening material; from 1 to 15% by weight of cationic softening material; and from 1 to 15% by weight of an amine. Compositions of the invention may take a variety of forms such as pastes, liquids, tablets, granules eventually attached to carrier substrates like tumble dryer sheets, preferably compositions of the invention are liquids, comprising an aqueous base. Compositions according to the present invention may be prepared by any well-known for the preparation of fabric conditioning compositions. One suitable method for instance involves the premelting of the active materials followed by the dispersing of the pre-melt in the aqueous base or vice versa. An especially useful method for the preparation of a fabric conditioning composition according to the present invention involves the pre-addition of the cellulose ether material to the aqueous phase, followed by the addition of the amphoteric fabric softening material to the aqueous phase. This final addition process may for instance involve the dispersing of a premelt including the amphoteric material plus eventual other active materials into the aqueous phase. In use the fabric conditioning compositions according to the present invention will preferably be diluted with water to form an aqueous liquor preferably comprising from 10 to 1000 ppm active material, the liquor will be contacted with fabrics, preferably in the rinse stage of a fabric washing process. The invention will be further illustrated by means of the following examples. Example I A fabric softening composition of the following composition: was prepared by co-melting the active ingredients and adding the co-melt to demineralised water at 80°C. The cellulose ether (Bermocoll CST 035) was added to this formulation at 75°C. The pH of the composition was adjusted with orthophosphoric acid to a value of 3.15. The performance of the composition was tested by rinsing 40g of pieces of woollen cloth in 1 litre of Wirral water (10 deg FH) whereto 2 ml of the composition was added, plus 0.01 g alkyl benzene sulphonate, and subsequently line drying the cloths. The dried woollen cloths were assessed for softness by a trained panel of four members. A piece of woollen cloth treated with the same composition was used as the control, a positive softening score indicates a better softness. The following results were obtained. % Polymer in product softening score 0.0 0.0 0.25 + 0.51 0.50 + 1.95 These results show an increase in softness on wool when adding a cellulose ether product as presently claimed to the fabric softener composition. Example II The fabric softening compositions of example I were tested in a front loading washing machine. The machine was loaded with 2.5 kg of towelling and polyester cotton cloth plus 10 monitors of woollen cloths, which were washed in with 100 g NS Persil Auto (UK) at 50°C in Wirral water (10 FH) and subsequently rinsed. 100 ml of the softening composition was added to the final rinse. The woollen cloths were line dried and assessed for softness as in example I; the following results were obtained: % polymer in product softening score 0 0.00 0.25 + 0.37 0.50 + 1.10 These results confirm that the use of selected cellulose ethers according to the invention improves the softening performance on wool. EXAMPLE III The following compositions were prepared by co-melting the amine oxide and the coactive, and adding a mixture of water and the cellulose ether at 80°C to the co-melt under agitation, followed by cooling and adjusting the pH to 3.0 with orthophosphoric acid. The softness scores were determined as in example I, the following results were obtained: COMPOSITION SOFTENING SCORE A 0.0 B 1.08 C 1.13 D 1.52 Again a good softening performance on wool was found in the presence of the specific cellulose ether. The names Bemocoll, DVT, Tylose, Methocol, Klucol, Natrosol, Arquad, Noramium, Stepantex, Synprolam, Ethomeen, Ethoduomeen, Ceranine, Lilaminox, Tween and Span used in this specification are all trade marks.

Claims: A fabric softening composition comprising a fabric softening material and a nonionic cellulose ether characterised in that: (i) the fabric softening material is an amphoteric fabric softening material selected from amphoteric or zwitterionic ammonium compounds having two long hydrocarbyl chains, each chain having from 8 to 25 carbon atoms, said softening material being capable of forming a particulate dispersion at a concentration of less than 1g/l at at least one temperature between 0°C and 100°C and having a solubility in water at pH2.5 at 20°C of less than 10g/l and (ii) the nonionic cellulose ether has a gel point of less than 58°C, an HLB of between 3.1 and 4.3, said cellulose ether being substituted with C₁₋₃ alkyl and/or hydroxyalkyl groups. A fabric softening composition as claimed in claim 1 having a pH of between 1.5 and 6.0 at a concentration of 1g/l of amphoteric softening material in water at 25°C. A composition as claimed in claim 1 or claim 2 wherein the amphoteric softener contains two hydrocarbyl groups with at least 14 C-atoms. A composition as claimed in any preceding claim wherein the cellulose ether has an HLB of between 3.3 and 3.8. A composition as claimed in any preceding claim wherein the cellulose ether has a gel point of between 30 and 55°C. A composition as claimed in any preceding claim wherein the cellulose ether is substituted with C₂₋₃ hydroxy alkyl groups. A composition as claimed to any preceding claim the cellulose ether is an ethyl hydroxyethyl cellulose ether. A composition as claimed in any preceding claim which also comprises a cationic fabric softening material. A fabric softening composition as claimed in any preceding claim which also comprises an amine fabric softening material. A composition as claimed in any preceding claim comprising an aqueous base.

Inventors: FOSTER FRANCIS GEOFFREY, TURNER GRAHAM ANDREW, FOSTER, FRANCIS GEOFFREY, TURNER, GRAHAM ANDREW
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1990
Main classification: C11D3
IPC codes: D06M13, D06M15, C11D1, C11D3, D06M101