FABRIC SOFTENING COMPOSITION

Abstract: A liquid fabric conditioning composition giving good water absorbency to fabrics. The composition comprises a substantially water-insoluble fabric softening compound characterised in that the fabric softening compound has a phase structure with greater than one dimensional order as defined by x-ray crystallography.

Description: FABRIC SOFTENING COMPOSITION Technical Field The present invention relates to fabric softening compositions, in particular the invention relates to fabric softening compositions that give excellent absorbency properties to fabrics. Background and Prior Art Rinse added fabric softener compositions are well known. However, a disadvantage associated with conventional rinse conditioners is that although they increase the soft feel of a fabric they decrease the fabric's absorbency. A decrease in the absorbency properties of a fabric means that its ability to take up water decreases, this is particularly disadvantageous with towels, where the consumer requires the towel to be soft and yet to have a high absorbency. Conventional liquid fabric softening compositions are in the form of dispersed colloidal particles of the fabric softening compound. The rinse added fabric softening compositions of the prior art soften by depositing dispersed colloidal particles of softening compound onto fabrics. These dispersed colloidal particles have a lamellar phase structure, that is the rinse conditioners of the prior art are structured such that they have only one-dimensional long range order. Typical fabric softening compositions contain a water insoluble fabric softening agent dispersed in water at a level of softening agent of up to 7% by weight in which case the compositions are considered dilute, or at levels from 7% to 30% in which case the compositions are considered concentrates. As well as reducing fabric absorbency properties fabric softening compositions formed from dispersed colloidal particles have complex, unstable structures. Because of this instability there are many problems associated with conventional fabric softening compositions. The principal problems are; physical instability at high and low temperatures; when frozen they are converted [irreversibly] to gels. Concentrated products, good dispersibility and dispensability, and storage stability at low or high temperature are however desired by the consumer. In an attempt to overcome the problems associated with dispersed colloidal particles, the prior art has turned to fabric conditioners in the form of solutions of fabric softening compounds in organic solvents. Systems of this type are exemplified by WO 94/17169A (Unilever) . However on contact with water dispersed colloidal particles are still formed. A further way of making solutions of fabric conditioners is by specific structural modifications. US 3 892 669 (Lever Brothers) discloses a clear, homogeneous, aqueous based liquid fabric softening composition and is limited to solubilised tetraalkyl quaternary ammonium salts having two short-chain alkyl groups and two long-chain alkyl groups, the longer chain groups having some methyl and ethyl branching. The solubilisers comprise aryl sulphonates, diols, ethers, low molecular weight quaternaries, sulphobetaines, and nonionic surfactants. The specification teaches that nonionic surfactants and phosphine oxides are not suitable for use alone and only have utility as auxiliary solubilizers. We have found that a novel fabric softening composition can be formed without any disadvantages of the prior art. The present invention discloses fabric softening compositions having excellent softening properties yet which also give excellent absorbency to fabrics. In addition, the composition of this invention also exhibits excellent hydrolytic stability. Definition of the Invention Thus according to one aspect of the invention there is provided a liquid fabric conditioning composition comprising a substantially water insoluble fabric softening compound and characterised in that the composition has a phase structure with greater than one-dimensional long range order as defined by x-ray crystallography. A further aspect of the invention provides the use of a fabric conditioning composition comprising a dispersed fabric softening compound and characterised in that the composition has a phase structure with greater than one-dimensional long range order as defined by x-ray crystallography to aid water absorbency by a fabric. The invention also provides a process for preparing a rinse conditioner according to the invention which comprises the steps of: i) adding the substantially water-insoluble fabric softening compound to cold water; ii) adding the resulting mixture to conventional detergent ingredients. A further process for preparing rinse conditioners of the invention comprises the steps of: i) adding the insoluble fabric softening compound to a mixture of cold water and nonionic surfactant. Detailed Description of the Invention X-ray diffraction is commonly used to investigate the structure of crystalline materials. X-ray diffraction of crystalline materials give diffraction patterns which consist of a series of peaks, and it is possible from the separation and inter-relationship of these peaks to define the structure of the crystalline material. The term 'd-spacing' is ascribed to the distance between each peak observed. The structure of the crystalline material is assessed by its d-spacing (also called D-spacing) . The term d-spacing ascribed to each peak is defined mathematically by Bragg's law: d = n λ 2d sinθ where λ is the wavelength (of X-ray source) ; θ is the angle over which the radiation is scattered (Bragg angle) ; d is a regular repeating distance between the layers, n is the number of orders of reflection Without wishing to be bound by theory it is believed that the dispersed fabric softening particles in the fabric conditioning composition of the present invention are structured in more than one dimension, preferably in three dimensions, and have short and long range order compared with the compositions of the prior art in which the dispersed fabric softening particles are structured in one dimension and have short range order. The dispersed fabric softening compound found in conventional liquid fabric conditioning products have liquid crystalline structures. The liquid crystalline structure found in fabric conditioning products, when subject to X-ray diffraction, produce characteristic X-ray scattering patterns typical of lamellar phases (only one-dimensional long range order) . A simple method for detecting the lamellar phase present in conventional rinse conditioners is that on dilution the d- spacings in the lamellar phase system become larger. In the present invention the d-spacings remain constant on dilution. The d-spacings of the dispersed fabric softening compound within the fabric conditioning composition can be measured in two ways using laboratory X-ray equipment. One method is to undertake the X-ray diffraction using a small angle of radiation (SAX) . This method detects short range order which is present in both crystalline and liquid crystalline (ie lamellar systems) structures. Information regarding the periodic (repeating) structure in both types of system can be obtained. The second method of X-ray diffraction is using a wide angle of radiation (WAX) . This method gives structural information for systems which are structured in more than one dimension (ie not lamellar systems) . By this method the structure of the lamellar phase or phases can be easily distinguished from systems with greater long range order. With WAX lamellar systems structured in only one dimension yield only a single Bragg reflection. Systems with more than one-dimensional order yield more complex X-ray diffraction patterns. WAX can be used to distinguish systems with more than one-dimensional order (greater than one long range order) from systems with only one-dimensional long range order (ie lamellar) . Thus the fabric conditioning compositions of the present invention can easily be distinguished from those of the prior art in that when assessed using wide beam X-ray (WAX) crystallography and structural information can be obtained whilst the rinse conditioners of the prior art only show one Bragg reflection and no long range structural information can be obtained It is preferable if the fabric softening compounds in the compositions of the present invention have a d-spacing value of less than 85 A, more preferably less than 70 A. Particle sizes of the fabric softening compound in the conditioning composition should be less than lOOu , preferably less than 50um, more preferably less than 20um. It is especially preferred if 90 wt% of the fabric softening compound has a particle size of less than 3um. The Fabric Softening Co nonnd The fabric softening compound is either a compound comprising a polar head group and a single alkyl or alkenyl chain of chain length greater than C 20 or more preferably a compound comprising a polar head group and two alkyl chains each having an average chain length greater than C 14 or a single chain length greater than C 20 . For both types of compound it is preferred if the polar head group is cationic such as a quaternary ammonium group. Preferably the fabric softening compound of the invention has two long chain alkyl or alkenyl chains with an average chain length greater than C 14 . More preferably each chain has an average chain length greater than C 16 , and more preferably at least 50% of each long chain alkyl or alkenyl group has a chain length of C 18 . It is preferred if the long chain alkyl or alkenyl groups of the fabric softening compound are predominantly linear. The fabric softening compositions of the invention are compounds molecules which provide excellent softening, characterised by chain melting -Lβ to Lα - transition temperature greater than 25°C, preferably greater than 35°C, most preferably greater than 45°C. This Lβ to Lα transition can be measured by DSC as defined in "Handbook of Lipid Bilayers, D Marsh, CRC Press, Boca Raton Florida, 1990 (Pages 137 and 337) . Substantially water-insoluble fabric softening compounds in the context of this invention are defined as fabric softening compounds having a solubility less than 1 x IO "3 wt% in demineralised water at 20°C. Preferably the fabric softening compounds have a solubility less than 1 x 10 "4 wt * , most preferably the fabric softening compounds have a solubility of from 1 x 10 "8 to 1 x IO "6 - It is especially preferred if the fabric softening compound is a water insoluble quaternary ammonium material which comprises a compound having two C 12 . 18 alkyl or alkenyl groups connected to the molecule via at least one an ester link. It is more preferred if the quaternary ammonium material has two ester links present. A preferred ester-linked quaternary ammonium material for use in the invention can be represented by the formula: R 1 R 1 IST (CH 2 ) n -T-R 2 (CH 2 ) n -T-R 2 wherein each R 1 group is independently selected from alkyl, hydroxyalkyl or C 2 . 4 alkenyl groups; X " is a suitable anion and wherein each R 2 group is independently selected from C 8 _ 28 alkyl or alkenyl groups; O O I I T is -C-O- or -O-C-; and n is an integer from 0-5. A preferred material of this class is N-N-di(tallowoyl-oxy- ethyl) N,N-dimethyl ammonium chloride. A second preferred type of quaternary ammonium material can be represented by the formula: OOCR 2 (R 1 ) 3 N + - (CH 2 ) n CH CH 2 OOCR 2 wherein R 1 , n, R 2 and X " are as defined above. Preferred materials of this class such as 1,2 bis [hardened tallowoyloxy]-3- trimethylammonium propane chloride and their method of preparation are, for example, described in US 4 137 180 (Lever Brothers) . Preferably these materials comprise small amounts of the corresponding monoester as described in US 4 137 180 for example 1-hardened tallowoyloxy -2-hydroxy trimethylammonium propane chloride. It is advantageous for environmental reasons if the quaternary ammonium material is biologically degradable. The fabric softening compound of the composition may also be compounds having the following formula: R 2 (R 1 -C-0-) m A(-0-C-B-N + -R 3 ) n nX " R 4 wherein X is an anion, A is an (m+n) valent radical remaining after the removal of (m+n) hydroxy groups from an aliphatic polyol having p hydroxy groups and an atomic ratio of carbon to oxygen in the range of 1.0 to 3.0 and up to 2 groups per hydroxy group selected from ethylene oxide and propylene oxide, m is 0 or an integer from 1 to p-n, n is an integer from 1 to p-m, and p is an integer of at least 2, B is an alkylene or alkylidene group containing 1 to 4 carbon atoms, R 1 , R 2 , R 3 and R 4 are, independently from each other, straight or branched chain C^C^ alkyl or alkenyl groups, optionally with substitution by one or more functional groups and/or interruption by at most 10 ethylene oxide and/or propylene oxide groups, or by at most two functional groups selected from O O O O O II II II I I II II -C-O-, -O-C-, -C-N-, -N-C-, and -O-C-O- or R 2 and R 3 may form a ring system containing 5 or 6 atoms in the ring, with the proviso that the average compound either has at least one R group having 22-48 carbon atoms, or at least two R groups having 16-20 carbon atoms, or at least three R groups having 10-14 carbon atoms. The level of fabric softening compounds is preferably from 3 to 60 wt% more preferably from 8 to 50 wt%, most preferably from 8 to 30 wt%. The composition may also contain nonionic fabric softening agents such as lanolin and derivatives thereof. Composition PH The compositions of the invention preferably have a pH of at least 1.5, and more preferably less than 5. Other Ingredients The fabric softening composition may also contain a nonionic stabilising agent, it is preferred if the nonionic stabilising agent is present at a level of from 0.1 to 10.0 % by weight and preferably at a level of from 0.2 to 2.5% by weight. Most preferred nonionic stabilising agents are the ethoxylated long chain fatty alcohols. The composition may also contain long chain fatty acid material for example C 8 - C 24 alkyl or alkenyl monocarboxylic acids or polymers thereof. Preferably saturated fatty acids are used, in particular hardened tallow C 16 - C 18 fatty acids. Preferably the fatty acid is non-saponified, more preferably the fatty acid is free for example oleic acid, lauric acid or tallow fatty acid. The level of fatty acid material is preferably at least 0.1%, more preferably at least 0.2% by weight. Especially preferred are dilutes in which the fatty acid material is present in an amount of from 0.25 wt% to 20 wt%. The weight ratio of quaternary ammonium compound to fatty acid material is preferably from 1:10 to 50:1. It is desirable if the viscosities of these fabric compositions lie in the range of from 1 mPa.s to 400 mPa.s at a shear rate of 110s "1 , preferably in the range of from 5 to 250 mPa.s and most preferably from 10 to 150 mPa.s. The composition can also contain one or more optional ingredients, selected from non-aqueous solvents, pH buffering agents, perfumes, perfume carriers, fluorescers, colorants, hydrotropes, antifoaming agents, antiredeposition agents, polymeric thickeners enzymes, optical brightening agents, opacifiers, anti-shrinking agents, anti-wrinkle agents, anti- spotting agents, germicides, fungicides, anti-oxidants, anti- corrosion agents, drape imparting agents, antistatic agents and ironing aids. Detergent Compositions This invention is also suitable for use in compositions designed for use in the main wash cycle of a washing machine. Such compositions would preferably have a high level of nonionic surfactant and include a builder material. The invention will now be illustrated by the following non¬ limiting examples. In the examples all percentages are expressed by weight. Comparative Examples are designated by letters, while Examples of the invention are designated by numbers. Preparation of Examples The Examples were prepared by the following methods: Preparation of Examples 1-4 Nonionic surfactant was warmed until molten and added to water containing antifoam at ambient temperature, the resulting mixture was cooled. Coarsely ground cationic active and other solid material was gradually added and the dispersion was mixed using high shear. Finally liquid minor ingredients were added. Preparation of Examples A-D A molten premix of cationic active and nonionic surfactant was gradually added to water containing antifoam at 75°C with high shear mixing. Minor ingredients were then added to the resulting dispersion. Examples 1 to 4 Examples 1 to 4 had the following compositions: Table 1 Examples expressed in weight % Example 1 2 3 4 HT-TMAPS 15 - 27 - HT-TMAPC - 15 - 27 nonionic 1 1 1 1 perfume 1 1 1 1 an ifoam 0 . 2 0 . 2 0 . 2 0 . 2 water To balance HT TMAPS = 1,2 bis[hardened tallowoyloxy]-3 trimethylammonium propane methylsulphate HT TMAPC = 1,2 bis[hardened tallowoyloxy]-3 trimethylammonium propane chloride Nonionic is coco alcohol ethoxylated with 20 ethylene oxide groups. Accosoft 540 HC ( ex Stepan) = H [OCH 2 CH 2 ] n N + CH 3 [CH 2 CH 2 NHCOR] CH 3 SO 3 where n is 1.7 and " COR is modified tallowoyl such that 90% of the unsaturation remains. DEEDMAC = N,N"di(tallowoyl-oxy-ethyl)N, -dimethyl ammonium chloride. Comparative Examples A-D Comparative Examples A-D had the following composition: Table 2 Wicking test The wicking properties of fabrics treated with the compositions were evaluated by adding 1ml of softening composition to 1 litre of tap water (10°FH) , at ambient temperature containing 0.001% (w/w) sodium alkyl benzene sulphonate (ABS) in a tergotometer. Three pieces of terry towelling (standard 8(20cm long by 3cm wide)) were added to the tergotometer pot. The cloths were treated or 5 minutes at 65 rpm, spin dried to remove excess liquor and line dried overnight. The strips of treated fabric were held vertically and lowered into a dish containing a 0.02% solution of direct red 81 dye, so that ca. 0.5cm of the fabric was below the surface of the water. The height to which the liquid rose up the strip was measured at intervals of time for a total of 15 minutes. The average height for each treatment was calculated. Higher values are indicative of better absorbency Table 3 demonstrates the results of the wicking test. in in

Claims: CLAIMS 1. A liquid fabric conditioning composition comprising a substantially water-insoluble fabric softening compound characterised in that the fabric softening compound has a phase structure with greater than one dimensional order as defined by x-ray crystallography. 2. A liquid fabric conditioning composition according to claim 1 in which the fabric softening compound has a d- spacing value of less than 85 A. 3. A liquid fabric conditioning composition according to claim 2 in which the fabric softening compound has a d- spacing value of less than 70 A. 4. A fabric softening composition according to any preceding claim in which the fabric softening compound is a cationic active. 5. A fabric softening composition according to claim 4 in which the fabric softening compound is a quaternary ammonium compound. 6. A fabric softening composition according claim 5 in which the fabric softening compound is a quaternary ammonium compound having at least one ester link. 7. A fabric softening composition according to claim 6 in which the fabric softening compound is an ester-linked quaternary ammonium material represented by the formula: R 1 R 1 N + (CH 2 ) n -T-R 2 (CH 2 ) n -T-R 2 wherein each R 1 group is independently selected from C x . alkyl, hydroxyalkyl or C 2 - alkenyl groups; X " is a suitable anion and wherein each R 2 group is independently selected from C 8 . 28 alkyl or alkenyl groups; O O I I T is -C-O- or -O-C-; and n is an integer from 0-5. 8. A fabric softening composition according to claim 5 in which the fabric softening compound is a quaternary ammonium material represented by the formula: OOCR 2 (R 1 ) 3 N + - (CH 2 ) n CH X" I CH 2 OOCR 2 wherein R 1 , n, R 2 and X " are as defined in claim 7. A process for preparing a rinse conditioner according to claim 1 which comprises the steps of: i) adding the substantially water-insoluble fabric softening compound to cold water; ii) adding the resulting mixture to conventional detergent ingredients. 10. A process for preparing a rinse conditioner according to claim 1 which comprises the steps of i) adding the insoluble fabric softening compound to a mixture of cold water and nonionic surfactant. 11. Use of a fabric conditioning composition according to claim 1 to aid water absorbency by a fabric.

Inventors: FRASER STUART BERNARD, NEILLIE WILLIAM FREDERICK SOUT, THORPE JACQUELINE MARIE, FRASER, STUART, BERNARD, NEILLIE, WILLIAM, FREDERICK, SOUTAR, THORPE, JACQUELINE, MARIE
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1996
Main classification: C11D1
IPC codes: C11D1, C11D3