DETERGENT COMPOSITION

Abstract: A detergent composition comprising a detergent active system, and a hydrotalcite-like material as defined in the formula (I): Mk+m Nn+p(OH)2A2<y->x. H2O, where: M is any 1+ or 2+ cation or combination thereof; N is any 3+ or 4+ cation or combination thereof; k is the sum of the individual mole fractions of the 1+ cations; m is the sum of the individual mole fractions of the 2+ cations; n is the sum of the individual mole fractions of the 3+ cations; p is the sum of the individual mole fractions of the 4+ cations where either but not both of k and m or n and p can be zero and k+m+n+p = 1, Az<y-> is any anion of charge y- and mole fraction z, wherein the grain size of the material is less than 110 Angström. Such compositions can be effective in removing unwanted colorants from detergent wash liquors thereby reducing colorant transfer in the wash.

Description: DETERGENT COMPOSITION A first aspect of the present invention relates to a hydrotalcite-like material; particularly to a hydrotalcite-like material of fine grain size, a second aspect relates to detergent compositions; particularly it relates to fabric-washing detergent compositions having improved colour care properties and a third aspect of the present invention relates to a method of controlling colorant migration for example between textile materials in a liquid. When washing mixed coloured fabrics, various factors can contribute to a loss of colour brightness, for example redeposition of soil from the wash liquor may result in colour dulling. When washing mixed coloured or (mixed) coloure'd and white fabrics there is a risk of colorant transfer through the wash liquor from one fabric to another or bleeding of colours in the same fabric which will result in discoloration, loss of colour brightness and/or staining of the fabric. In textile production processes it is often necessary to produce or finish textiles using 'wet' processes. Again there is a risk of colorant transfer. For example, garments woven or knitted from a mixture of coloured yarns often need to be wet finished or scoured to achieve maximum fastness. When printed textiles are produced it is often necessary to wash off unbound dye and this process can result in dye transfer onto unprinted or differently coloured areas. These colorant transfer processes may give the same undesirable results as are encountered in fabric washing. With fashion moving towards coloured clothing and textile materials, especially multi-coloured the problem of colorant transfer in liquids has become more acute. Various proposals have been made in the art to resolve the problem of colorant transfer but, in the main, they have relied on compositions with bleaching systems to remove excess colorants from solution. The main drawback of these compositions is that they exert a rather strong direct fabric or textile dye bleaching, tending to cause fading of the coloured fabrics or textiles. EP 0 206 799 (The Dow Chemical Company) discloses certain crystalline anion exchange materials represented by a formula, the materials consisting of complex inorganic salts of mixed metal hydroxides and hydra ed oxides having an excess positive charge. The charge is said to be balanced by an exchangeable anion. Possible uses of the anion exchange material are said to be in controlling colorant migration in a liquid, in laundering clothes, in removing sulphonated polystyrene from corn syrup and for forming pigments. The formula of the anion exchange material excludes those crystalline salts where substantially no oxide is present. EP 0 207 707 (The Dow Chemical Company) discloses certain anion exchange materials with anion exchange properties above 160°C. The materials are represented by the same formula as the materials of EP 0 206 799. Possible uses are said to be removing chromates or dichromates from waste water streams, removing silicates from industrial boiler systems or removing dye migration from one item to another. The composition for laundering clothes proposed by EP 0 206 799 suffers from the disadvantage that it will be an inefficient detergent composition. Efficient washing of mixed coloured or coloured and white fabrics requires not only control of colourant transfer but also efficient cleaning of the fabric. EP 0 345 587A (Henkel KGaA) discloses the use of cationic, non-silicate layer compounds having the general formula (a) Mg χ Al (OH) y A z .nH 2 0 (a) where A is a non-silicate anion, and l<x<5, y>z, (y+z) = 2x + 3, and 0<n'<10 in a detergent composition comprising 8% by weight of alkyl benzene sulphonate and 5% by weight of (a) . The non-silicate layer compound is said to reduce fabric encrustation caused by zeolite-containing detergent compositions. For some applications is necessary or desirable to use a dye absorbing material within a specific particle size range. This leads to problems in controlling absorption kinetics or total capacity by means of particle size alone. For laundry applications it is desired to achieve fast kinetics to ensure that free dye is removed from the wash liquor before it has time to redeposit on a lightly coloured item whereas for other dye absorption applications it is more important to maximise the total amount of dye that can be absorbed by a unit mass of the material. Prior art materials tended to be too slow or to have a low total absorption capacity. The present invention seeks to mitigate the disadvantages of the prior art and provide an alternative material for controlling colorant migration in a liquor. Thus, the present invention concerns other anion exchange materials being related to a compound of the formula Mg 6 Al 2 (OH) 16 C0 3 .4H 2 0 known as hydrotalcite in any form, and for convenience referred to hereinafter as hydrotalcite-like materials. The hydrotalcite-like materials useful in detergent compositions of the present invention or in method of reducing colourant migration in a liquid according to the present invention can be described by formula I below: M k+n N- +p (OH) 2 A/ " x.H 2 0 I where: M is any 1+ or 2+ cation or combination thereof N is any 3+ or 4+ cation or combination thereof k is the sum of the individual mole fractions of the 1+ cations m is the sum of the individual mole fractions of the 2+ cations n is the sum of the individual mole fractions of the 3+ cations p is the sum of the individual mole fractions of the 4+ cations where either but not both of k and m or n and p can be zero and k+m+n+p=l. A z y~ is any anion of charge y- and mole fraction z, or combination of anions of similar or differing y- and k+2m+3n+4p-2-zy=_0 and x can range from 1 to 100. Examples of the cations M in the above formula are Li + , Mg 2 *, Zn 2 \ Fe 2 \ Cu 2 \ Sn 2 % Ca 2t and Sr 2÷ . Suitable N cations include Ai 3+ , Fe 3+ , Ti + and Sn + . Preferred divalent cations are Zn 2 Cu 2t or Mg 2+ or a combination of these ions, or a combination with other divalent cations. The anion A may be an inorganic or organic anion. Preferred inorganic anions A are Cl " , N0 3 " , S0 4 2" , C0 3 2" and OH " . Examples of organic anions are carboxylate ions such as citrate and stearate. Examples of hydrotalcite-like materials of this invention are:- Mg 6 Al 2 (0H) 16 (A-y-) xH 2 0 Cu 16 Al 2 (OH) 36 (Cl 2 ) xH 2 0 In EP 431867 we have described examples of hydrotalcite-like materials which fall within the general formula I, for use in fabric washing detergent compositions and for controlling colourant migration between textiles in a liquid. We have now found that certain hydrotalcite-like materials can for example be characterised by the grain size of the material. In GB 2 075 989A (Kyowa Chemical Industry Co. Ltd/MIYATA) there are disclosed certain hydrotalcites having specific surface area of not more than 30 m 2 /g. This prior specification also discloses that preferred hydrotalcites have a grain size of at least 300A. The hydrotalcites are used to lend thermal or ultraviolet stability to thermoplastic resins. In 'Physico-Chemical Properties of Synthetic Hydrotalicites in Relation to Composition' by Shigeo Miyata Clays and Clay Minerals, Vol 28, No. 1, 50-56, 1980) there are disclosed various Mg/Al hydrotalcites which are subjected to hydrothermal treatment for a range of times and temperatures. Table 1 refers to a sample of Mg 6 Al 2 (OH) 16 C0 3 . 4H-0 having a grain size of 112 A. Accordingly, a first aspect of the present invention provides a hydrotalcite-like material as defined in formula I of grain size less than 110 A. Hydrotalcite-like materials of grain size less than 110 A can absorb colorants at a faster rate than materials of grain size greater than 110 A. These fine grain size materials can also have a greater dye binding capacity than materials of grain size greater than 110 A. Preferably, the grain size of the hydrotalcite-like materials is less than 10OA, more preferably it is between 40 and 100 A. In the present invention grain sizes are measured on the <001> direction by x-ray diffraction. Accordingly, a second aspect of the present invention provides a detergent composition comprising: a. a detergent active system, and b. a hydrotalcite-like material as defined in formula I of grain size less than 110 A. The hydrotalcite-like material is preferably present in the detergent composition of the invention at a level of at least 1% by weight, more preferably at least 5% by weight, most preferably between 5% by weight and 30% by weigh . Such compositions can be effective in removing unwanted colorants from detergent wash liquors thereby reducing colorant transfer in the wash and the tendency for fabrics to become dull after washing. While not wishing to be bound by theory it is thought that hydrotalcite-like materials control colorant transfer in a liquid by adsorbing anionic species such as dyes thus preventing their redeposition on the fabric or textile. In a wash liquor or textile production process it is therefore important that the anion exchanger adsorbs relatively quickly since in the low liquor to cloth ratios commonly encountered in the textile industry or in a typical fabric washing situation where differently coloured fabrics are in close proximity, the redeposition of colorants can occur speedily due the abundance of available redeposition sites. Preferably the hydrotalcite-like material has a particle size (as measured by light scattering) , less than 250μm, more preferably less than lOOμm. Since the hydrotalcite like materials are anion exchangers it is preferred that the detergent active system is non-anionic, preferably nonionic in nature. In particular, the detergent active system can comprise at least 25% by weight of the system of nonionic detergent active preferably at least 30%, more preferably 40% by weight of the system. In this way compositions according to the invention may provide not only good colour care for mixed coloured/white fabric loads but also provide an efficient detergent composition. Examples of suitable nonionic surfactants that can be included in the detergent active system include: 1. The polyethylene oxide condensates of alkyl phenol. eg. the condensation products of alkyl phenols having an alkyl group containing from 6 to 12 carbon atoms in either a straight chain or branched chain configuration, with ethylene oxide, the said ethylene oxide being present in amounts equal to 3 to 30, preferably 5 to 14 moles of ethylene oxide per mole of alkyl phenol. The alkyl substituent in such compounds may be derived, for example, from polymerised propylene, di-isobutylene, octene and nonene. Other examples include dodecylphenol condensed with 9 moles of ethylene oxide per mole of phenol; dinonylphenol condensed with 11 moles of ethylene oxide per mole of phenol; nonylphenol and disooctylphenol condensed with 13 moles of ethylene oxide. 2. The condensation product of primary or secondary aliphatic alcohols having 8 to 24 carbon,atoms, in either straight chain or branched chain configuration, with from 2 to about 40 moles, preferably 2 to about 9 moles of ethylene oxide per mole of alcohol. Preferably, the aliphatic alcohol comprises between 9 and 18 carbon atoms and is ethoxylated with between 2 and 9, desirably between 3 and 8 moles of ethylene oxide per mole of aliphatic alcohol. The preferred surfactants are prepared from primary alcohols which are either linear (such as those derived from natural fats or prepared by the Ziegler process from ethylene, eg. such as the Lutensols, Dobanols and Neodols which have about 25% 2-methyl branching (Lutensol being a Trade Name of BASF, Dobanol and Neodol being Trade Names of Shell) , or Synperonics, which are understood to have about 50% 2-methyl branching (Synperonic is a Trade Name of ICI) or the primary alcohols having more than 50% branched chain structure sold under the Trade Name Lial by Liquichimica. Specific examples of nonionic surfactants falling within the scope of the invention include Dobanol 45-4, Dobanol 45-7, Dobanol 45-9, Dobanol 91-2.5, Dobanol 91-3, Dobanol 91-4, Dobanol 91-6, Dobanol 91-8, Dobanol 23-6.5, Synperonic 6, Synperonic A7, Synperonic 14, the condensation products of coconut alcohol with an average of between 5 and 12 moles of ethylene oxide per mole of alcohol, the coconut alkyl portion having from 10 to 14 carbon atoms, and the condensation products of tallow alcohol with an average of between 7 and 12 moles of ethylene oxide per mole of alcohol, the tallow portion comprising essentially between 16 and 22 carbon atoms. Secondary linear alkyl ethoxylates are also suitable in the present compositions, especially those ethoxylates of the Tergitol series having from about 9 to 15 carbon atoms in the alkyl group and up to about 11, especially from about 3 to 9, ethoxy residues per molecule. The compound formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The molecular weight of the hydrophobic portion generally falls in the range of about 1500 to 1800. Such synthetic nonionic detergents are available on the market under Trade Name, of "Pluronic", supplied by Wyandotte Chemicals Corporation. When the detergent active system comprises a mixture of anionic and nonionic actives, the preferred nonionic material or mixtures thereof for use in this invention will have an HLB (hydrophillic-lipophilic balance) of not- more than 10.5, preferably in the range of from 6 to 10,. most preferably in the range of 8 to 9.5. As explained,, the composition can contain one or a mixture of more than one nonionic detergent-active materials. The mixture can contain one or more nonionic materials having an HLB of more than ' 10.5, providing the average HLB of the mixture of nonionic materials is not more than 10.5. The HLB scale is a known measure of hydrophiliic-lipophilic balance in any compound. It is fully defined in the literature, for example in "Nonionic Surfactants", Volume 1, edited by M J Schick. A method of determining the HLB of a mixture of nonionic materials is also defined in this reference. Preferred nonionic materials are the alkoxylate adducts of fatty compounds selected from fatty alcohols, fatty acids, fatty esters, fatty amides and fatty amines. The fatty compound contains at least 10 carbon atoms and the nonionic material contains an average of less than 8 alkylene oxide groups per molecule. Alkylene oxide adducts of fatty alcohols useful in the present invention, preferably have the general formula: R 10 -0-(C n H 2n O) y H wherein R 10 is an alkyl or alkenyl group having at least 10 carbon atoms, most preferably from 10 to 22 carbon atoms, y is preferably not more than 10, such as from 0.5 to about 3.5, and n is 2 or 3. Examples of such materials include Synperonic A3 (ex ICI) , which is a C 13 -C 15 alcohol with about three ethylene oxide groups per molecule, and E pilan KB3 (ex Marchon) which is lauric alcohol 3EO. Alkylene oxide adducts of fatty acids useful in the present invention, preferably have the general formula: O t - 1 n 0 -C 0-0 (C n H 2n O) y H, wherein R 10 , n and y are as given above. Suitable examples include ESONAL 0334 (ex Diamond Shamrock) , which is a tallow fatty acid with about 2.4 ethylene oxide groups per molecule. Alkylene oxide adducts of fatty esters useful in the present invention include adducts of mono-, di- or triesters of polyhydric alcohols containing 1 to 4 carbon atoms; such as coconut or tallow oil (triglyceride) 3EO (ex Stearine Dubois) . Alkylene oxide adducts of fatty amides useful in the present invention preferably have the general formula: wherein R 10 is an alkyl or alkenyl group having at least 10 carbon atoms, most preferably from 10 to 22 carbon atoms, n is 2 or 3 and x and z in total are not more than 4.0, preferably from about 0.5 to about 3.5, while one of x and z can be zero. Examples of such materials include tallow monoethanolamide and diethanolamide, and the corresponding coconut and soya compounds. Alkylene oxide adducts of fatty amines useful in the present invention preferably have the general formula: wherein R 10 and n are as given above, and x and z in total are preferably not more than 4.0, most preferably from about 0.5 to about 3.5. Examples of such materials include Ethomeen T12 (tallow amine 2E0, available from AKZO) , Optameet PC5 (coconut alkyl amine 5EO) and Crodamet 1.02 (oleylamine 2EO, available from Croda Chemicals). Cationic detergent-active materials suitable for use herein include quaternary ammonium surfactants and surfactants of a semi-polar nature, for example amine oxides. Amounts of amphoteric or zwitterionic detergent compounds can also be used in the composition of the invention, but this is not normally desired owing to their relatively high cost. If any amphoteric or zwitterionic detergent compounds are used, it is generally in small quantities relative to the much more commonly used anionc and/or nonionic detergent-active compounds. The effective amount of the detergent-active compound or compounds used in the composition of the invention will generally be in the range of from 5 to 50% by weight, preferably from 6 to 30% by weight based on the total composition. The detergent composition according to the invention may also contain a detergency builder, which can be an inorganic builder or an organic builder, in an amount generally within the range of from about 5% to about 80%, preferably from 10% to 60% by weight. Examples of phosphorus-containing inorganic detergency builders, when present, include water-soluble salts, especially alkali metal pyrophosphates, orthophosphates and polyphosphates. Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphtes, phosphates and hexametaphosphates. Examples of non-phosphorus-containing inorganic detergency builders, when present, include water-soluble alkali metal carbonates, bicarbonates, silicates and crystalline and amorphous alumino silicates. Specific examples include sodium carbonate (with or without calcite seeds), potassium carbonates, sodium and potassium bicarbonates and silicates. Examples of organic detergency builders, when present, include the alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates, polyacetal carboxylates and polyhydroxysylphonates. Specific examples include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetracetic acid, nitrilotriacetic acid, oxydisuccinic acid, melitic acid, benezene polycarboxylic acids and citric acid. The detergent compositions of the invention may also contain any of the conventional additives in amounts in which such materials are normally employed in fabric-washing detergent compositions or textile washing detergent compositions and which serve to further improve the laundering or scouring characteristics. Examples of these additives include lather boosters , anti-foaming agents, alkaline materials such as sodium silicates, fabric softening agents, enzymes such as proteolytic, lipolytic and amylolytic enzymes, corrosion inhibitors, inorganic salts, sequestering agents, bleaching agents, colouring agents and perfumes, so long as these additives do not adversely influence the invention. In a preferred embodiment the detergent compositions do not contain fluorescent agents or optical bleaching agents as these additives could change the hue of the original textile or fabric colours. The detergent compositions of the invention can be manufactured and presented in the form of a powder, including granules, flakes, etc; liquid; paste; or bar or included in a sachet. Detergent powder compositions according to the invention can be prepared using any of the conventional manufacturing techniques commonly used or proposed for the preparation of fabric washing detergent compositions. These include spray-drying or spray cooling and subsequent dry-dosing of sensitive ingredients not suitable for incorporation prior to the drying or heating step. A third aspect of the present invention relates to a method of controlling colorant migration in a liquid by contacting said liquid with a sufficient amount of a hydrotalcite-like material of formula I of grain size less than 110 A. Such a method can be effective in removing unwanted colourants including anionic dyes from fabric washing liquors and textile treatment liquors. The hydrotalcite-like material is present in the liquid in an amount from 0.01-30 g/1. Preferably from 0.05 to 10 g/1. 1. A magnesium/aluminium hydrotalcite-like material useful in the present invention was prepared as follows: An alkali solution comprising 150 litres of a mixed sodium hydroxide/sodium carbonate alkali solution and having a total anion concentration of 5M and a hydroxide to carbonate ratio of 3:1, was added to a vessel containing around 66 litres of demineralised water to raise the pH from neutral to around pH 10. A solution of aluminium sulphate and magnesium sulphate having a total metal ion concentration of 2M and a magnesium to aluminium ratio of 3:1, was added to the vessel and the vessel contents were agitated. The rate of addition of the sulphate solution was adjusted to maintain a pH in the solution of 10 to 10.5. Immediate precipitation occurred on addition of the sulphate solution, however, the resulting slurry was cooled to maintain a temperature of 25°C- The reaction time was approximately 50 minutes, plus 10 minutes agitation once additon of the solutions was complete. The slurry was then pressed to form a filter cake and the cake was washed with demineralised water. The wash filtrate was tested for the presence of sulphate anion using barium chloride solution, which indicated that most of the sulphate had been removed from the cake. The cake was then air dried for 1 hour and then passed through a ring drier and then milled in a fluid energy mill to a particle size of 5 to 7 microns. 2. A magnesium/aluminium hydrotalcite-like material useful in the present invention was prepared in the following way. To 98 litres of water 19.5 kg of sodium hydroxide was added followed by 25kg of magnesium nitrate and 18.3kg of aluminium nitrate dissolved in 73 lites of water to give a Mg:Al ratio of 3:1. The nitrate solution was added over a period of 30 minutes with stirring. The resulting precipitate was filtered, washed and oven dried at approximately 120°C and micronised using a fluid energy mill. 3. A zinc/aluminium hydrotalcite-like material useful in the present invention was prepared in the following way: 3 litres of a mixed sodium hydroxide/sodium carbonate alkali solution having a total anion concentration of 5 Molar and a hydroxide to carbonate ratio of 3:1 and 3 litres of metal sulphate solutions were prepared having a total metal ion concentration of 2M and a zinc to aluminium ratio of 3:1. These solutions were introduced over a period of 15 minutes, into an agitated 1.5 litre water pool, in a vessel fitted with an overflow. The flow rate of the alkali solution was adjusted to maintain the pH at 6.5 - 7. The first 2 litres from the overflow were discarded. Immediate precipitation occured. The solid was then removed by filtration and was then washed and carefully oven dried at 110°C to avoid loss of surface area. Care must always be taken when drying hydrotalcite-like materials if surface area is to be retained. The material was then ground and fractionated using an air swept sieve. The following Examples illustrate the invention. Example 1 A sample of Mg/Al hydrotalcite was prepared as in method 1 above. The grain size of this material was measured by X-ray powder diffraction using a Philips series 17 diffractometer and Cuk ό radiation. The (001) reflection peak was converted into full-width-at-half- maximum values using either FWHML = 2.00 or FWHMSQL = 1.29 B B by measuring the breadth (B) and fitting these to either lorentzian or squared-lorentzian profiles. The peak position and FWHM values are inserted into the Scherrer equation described in EF Kaelbu, Handbook of X-rays, McGraw-Hill, (1967) from which the grain size can be calculated. The rate of colorant absorption of this hydrotalcite was compared to a commercially available Mg/Al hydrotalcite sold under the trade name KYOWA SHT-4A ex Kyowa by measuring the absorbance of filtered samples of liquid, as compared to a blank, at timed intervals. The rate of absorbtion was then expressed as an absorbance ratio. absorbance ratio = absorbance at time t = t absorbance at time t = 0 The lower the absorbance ratio, the faster the rate of colorant absorbtion by the hydrotalcite-like material. A solution in demineralised water of lg/1 nonionic surfactant (Synperonic A7 (ex ICI)), 0.01 mol dm "3 sodium chloride and 0.01 g/1 dyestuff (Direct Red 80: CI35780) was prepared. 200ml of the solution was placed in a water bath and maintained at a temperature of either 25°C or 40°C. The solution was stirred at all times. 5ml samples were withdrawn at timed intervals and filtered through a 0.45μm cellulose nitrate filter. The absorbance of each sample was determined against a water/nόnionic/NaCl standard at 525nm as measured on a UV/visible spectrophotometer this being the maximum absorbtion for Direct Red 80. After the first reading 0.14g of Mg/Al hydrotalcite according to the invention was added. Samples were then withdrawn at timed intervals. This procedure was repeated with KYOWA SHT-4A. Material Grain Particle Absorbance Ratio at 525 run Size Size t=lmin t=2min t=3min t=4min t=5min A μ Mg/Al 53 5-7 0.009 0.000 0.000 0.000 0.000 Hydrotalcite KYOWA 373 5-7 0.856 0.761 0.635 0.561 0.461 SHT-4A These results show that a hydrotalcite-like material of grain size less than 110 A has a faster rate of colorant absorbtion than a commercially available hydrotalcite. Example 2 The rate of colorant absorption of a Mg/Al hydrotalcite material prepared as in method 2 above was compared to that of a material prepared as in method 2 excepting that the solution was aged by heating at 90°C to 100°C for 2 hours before being filtered, by measuring the absorbance ratio as described in Example 1. The grain size of both materials was measured by the method described in Example 1. Material Grain Particle Absorbance Ratio at 525 nm Size A Size μm t-lmin t=2min t=3min t=4min Mg/Al 87 56-100 0.065 0.021 0.010 0.003 Hydrotalcite Method 2 Mg/Al 250 56-100 0.990 0.911 0.797 0.743 Hydrotalcite Method 2 and Aged These results show that a hydrotalcite-like material of grain size less than 110 A has a faster rate of colorant absorbtion than a hydrotalcite-like material of grain size 250 A. Example 3 The rate of colorant absorption of a Mg/Al hydrotalcite-like material according to the invention and prepared as in method 3 above but using the reaction conditions and materials of method 1 was compared to that of a Mg/Al hydrotalcite-like material also prepared as in method 3 and aged by adjusting the pH to 11.5 and heating at 90°C to 100°C for 6 hours before filtering. The absorbance ratio was measured as described in Example 1. The grain size of both materials was measured by the method described in Example 1. Material Grain Size Particle Size Absorbance Ratio A Microns t=lmin t=2min t=3min Mg/Al Hydrotalcite 60 56-80 0.559 0.454 0.281 Method 3/1 Mg/Al Hydrotalcite 160 56-80 0 . 839 0 .748 0 .426 Method 3/1 and Aged These results show that a hydrotalcite-like material of grain size less than 110 A has a faster rate of colorant absorbtion than a hydrotalcite-like material of grain size 250 A. Colorant binding capacities were measured by adding 200ml of a solution of 0.lg of dyestuff in 1 litre of water to a flask containing 1 litre of water. 0.06g of the hydrotalcite sample was then added to the flask which was shaken vigorously for 2 minutes and left to stand for 2 hours with shaking every 15 minutes. The solution was then filtered and its absorbancy measured (as described in Example 1) and compared to an identical solution with hydrotalcite omitted. The binding capacity was then calculated from the difference between these absorbancies and expressed as a percentage weight for weight. ' λ Binding Capacity % w/w Dyestuff max Mg/Al Mg/Al nm Hydrotalcite Hydrotalcite Method 3/1 Method 3/1 (aged) Procion Turquoise HA grain size 60A grain size 16θA ex ICI 670 6.6 3.5 Example 4 The colorant binding capacity and the rate of colorant uptake of Zn/Al hydrotalcite-like material according to the invention and prepared as in method 3 were compared with those of that of Zn/Al hydrotalcite material prepared by the same method except that prior to removal of solid from the slurry it was adjusted to a pH of 11.5 and aged at 95°C for 6 hours. The evaluation method used for dye concentration measurement were the same as for example 1. Material Grain Particle Absorbance Ratio size size A μ 20s 40s 60s 2min 5min Zn/Al Hydrotalcite Method 3 <50 56-100 0.771 0.716 0.646 0.553 0.397 Zn/Al Hydrotalcite Method 3 230 56-100 0.915 0.876 0.841 0.800 0.670 Colourant binding capacities were measured using the method for Example 3. λ Binding Capacity % w/w Dyestuff max Zn/Al Hydrotalcite Zn/Al Hydrotalcite nm Method 3 Method 3 Procious Turquois HA 670 3.5 2.2 ex ICI These results show that the faster rate of colour absorption and the greater dye binding capacity also occur with the zinc/Aluminium hydrotalcite material of grain size below 110 A. Example 5 A Zn/Al hydrotalcite-like material was prepared by the method disclosed in EP 431867. The grain size was measured to be 100 A and half the material was aged to increase the grain size to 140 A. The materials were then treated by the same methods as used for Example 1 and the results are; Absorbance Ratio Grain size Particle size lmin 2min 5min Zn/Al 100 A 56-80 μm 0.867 0.799 0.647 Hydrotalcite Method of EP 431867 Zn/Al 140 A 56-80 μm 0.892 0.846 0.734 Hydrotalcite Method of EP 431867 and Aged These results demonstrate that moving below the 110 A grain size gives increased rate of dye absorption. Example 6 The colorant binding capacity of a Mg/Al hydrotalcite-like material according to the invention and prepared as in method 1 above was compared to that of a Mg/Al hydrotalcite-like material prepared as in method 2 above excepting that the solution was aged by heating at 90°C to 100°C for 2 hours before being filtered. Both particles has a size in the range of 5-7 μm. Binding Capacity % w/w Dyestuff max Mg/Al Mg/Al nm Hydrotalcite Hydrotalcite method 1 method 2 Grain size 53A and Aged. Grain size 250A Neutrichrome Navy 580 20 S-B ex ICI Levafix Brilliant 535 17 Red E-4BA ex Bayer Irqalan Grey BRL 570 15 200% ex Ciba-Geigy Acidol Black M-SRL 575 24 12 ex BASF These results show that a hydrotalcite-like material of grain size less than 110 A according to the invention has a greater dye binding capacity than a. hydrotalcite-like material of grain size 250 A.

Claims: - 23 - Claims 1. A hydrotalcite-like material as defined in formula (I), M fc* . N n+p (0H) 2 A -x. H 2 0 (I) where M is any 1+ or 2+ cation or combination thereof; N is any 3+ or 4+ cation or combination thereof; k is the sum of the individual mole fractions of the 1+ cations; m is the sum of the individual mole fractions of the 2+ cations; n is the sum of the individual mole fractions of the 3+ cations; p is the sum of the individual mole fractions of the 4+ cations where either but not both of k and m or n and p can be zero and k+m+n+p = 1 and A. y" is any anion of charge y- and mole fraction 2, or combination of anions of similar or differing y- and x can range from 1 to 100, characterised in that the grain size of the material is less than 110 A. 2. A hydrotalcite-like material as claimed in claim 1 wherein the grain size is less than or equal to 100 Angstrom. 3. A hydrotalcite-like material as claimed in claim 1 or 2 wherein the grain size is from 40 to 100 A. 4. A hydrotalcite-like material as claimed in any preceding claim wherein M is magnesium and N is aluminium. 5. A hydrotalcite-like material as claimed in any preceding claim wherein the hydrotalcite-like material has the following formula: Mg 6 Al 2 (OH) 16 (A/ " ) 2 xH 2 0. 6. A hydrotalcite-like material as claimed in any preceding claim wherein the material has a particle size of less than 250 microns. 7. A detergent composition comprising: a. a detergent active system, and b. a hydrotalcite-like material as defined in any one of claims 1 to 6. 8. A method of reducing colorant migration in a liquid by contacting said liquid with a sufficient amount of a material substantially as described by formula (I) as defined in claim 1. 9. A method as claimed in claim 8 wherein the hydrotalcite-like material is present in the liquid at a concentration of at least 0.01 g/1 "1 . 10. A method as claimed in claim 8 or claim 9 wherein the hydrotalcite-like material is present in the liquid at a concentration of at least 0.05 g/1 "1 . 11. A method of preparing a hydrotalcite-like material substantially as described by formula (I) as defined in claim 1 comprising the steps of reaching a solution of a salt of metal M with a salt of metal N under alkali conditions followed by removal of the precipitate.

Inventors: COCKETT KEITH ROBERT FRASER, CONCANNON MARTIN, WEBB MAURICE, COCKETT, KEITH, ROBERT, FRASER, CONCANNON, MARTIN, WEBB, MAURICE
Applicants: CROSFIELD JOSEPH & SONS, JOSEPH CROSFIELD & SONS
Application year: 1991
Main classification: C01F7
IPC codes: C01F7, C11D3