DETERGENT COMPOSITION

Abstract: A detergent composition for washing and softening fabrics comprises a detergent active system, preferably a mixture of soap, non-soap anionic and nonionic detergent active materials, a water-soluble carbonate, such as sodium carbonate, ideally mixed with sodium bicarbonate, a seed crystal such as calcite and a fabric softening clay. The calcite is clay ratio is less than 1.8:1.

Description: This invention relates to a detergent composition, particularly to a detergent composition for washing and softening fabrics. Detergent compositions generally contain in addition to a detergent active material to remove soil from fabrics, a detergency builder material whose role is primarily to prevent calcium ions in hard water from reducing the efficiency of the detergent active material. For many years, phosphates such as sodium tripolyphosphate have been used as detergency builders. It has become desirable for a number of reasons to provide detergent compositions which are free or essentially free of phosphorus. A number of alternative, non-phosphorous, builders have been proposed, especially a mixture of an alkali metal carbonate, such as sodium carbonate, with a calcium carbonate seed material, such as calcite (see GB 1 437 950 - UNILEVER Case No. C720), and it is compositions containing such builders to which the present invention is directed. The use of a sodium carbonate/calcite builder mixture in place of sodium tripolyphosphate leads to a number of differences, in particular a greater tendency to harshen fabrics. Harshening is a phenomena which occurs with many detergent compositions, where the feel of the fabric becomes harsh after washing. This occurs particularly with fabrics formed of natural fibres such as cotton and may be due in part to the removal of natural lubricating materials from the fibres of the fabric. A number of materials are suggested in the art as fabric softeners, capable of reducing the degree of harshening obtained in the wash. Such a class of materials are the smectite clays having a high exchange capacity as disclosed in GB1400898 (Procter & Gamble). It has been found however that such clays are most effective when used in the presence of a peptising agent, such as sodium tripolyphosphate. Such clays are less effective however in the absence of tripolyphosphate ions. The art has not therefore recommended clays as effective fabric softening or anti-harshening agents for use with detergent compositions in which alkali metal carbonates are used in place of tripolyphosphate salts. We have now discovered that the fabric harshening effect of compositions containing a sodium carbonate/calcite builder mixture can be substantially overcome by the presence of a fabric softening clay material. Thus, according to the invention, there is provided a detergent composition for washing and softening fabrics, which is essentially free of phosphate builder and comprises: (i) from 2% to 40% by weight of at least one non-soap detergent active material; (ii) from 5% to 40% by weight of a builder material which comprises a water soluble carbonate in an amount which is at least 5% by weight of the composition; (iii) from 10% to 60% by weight of a water-insoluble carbonate having a surface area of at least 10 m²/g as calcium carbonate seed crystal; and (iv) up to 35% by weight of a fabric softening clay material; the weight ratio of the seed crystal to the clay material being less than 1.8:1. The compositions of the invention necessarily contain at least one non-soap detergent active material, preferably at a level of 5 to 40% by weight. These materials are preferably selected from non-soap anionic and nonionic detergent actives and mixtures thereof. Other detergent active materials, including soaps, may also be used but this will normally be in admixture with non-soap anionic and/or nonionic materials. The non-soap (synthetic) anionic detergent active compound is usually the water-soluble alkali metal salt of an organic sulphate and sulphonate having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates, especially those obtained by sulphating higher (C₈-C₁₈) alcohols produced for example from tallow or coconut oil, sodium and potassium alkyl (C₉-C₂₀) benzene sulphonates, particularly sodium linear secondary alkyl (C₁₀-C₁₅) benzene sulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulphates and sulphonates; sodium and potassium salts of sulphuric acid esters of higher (C₈-C₁₈) fatty alcohol-alkylene oxide, particularly ethylene oxide, reaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralised with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyl taurine; alkane monosulphonates such as those derived by reacting alpha-olefins (C₈-C₂₀) with sodium bisulphite and those derived from reacting paraffins with SO₂ and Cl₂ and then hydrolysing with a base to produce a random sulphonate; and olefin sulphonates, which term is used to describe the material made by reacting olefins, particularly C₁₀-C₂₀ alpha-olefins, with SO₃ and then neutralising and hydrolysing the reaction product. The preferred anionic detergent compounds are sodium (C₁₁-C₁₅) alkyl benzene sulphonates and sodium (C₁₆-C₁₈) alkyl sulphates. Suitable nonionic detergent compounds include in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionic detergent compounds are alkyl (C₆-C₂₂) phenols-ethylene oxide condensates, generally up to 25 EO, ie up to 25 units of ethylene oxide per molecule, the condensation products of aliphatic (C₈-C₁₈) primary or secondary linear or branched alcohols with ethylene oxide, generally up to 40 EO, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic detergent compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides. We have found particular advantages from an anti-harshening point of view, when the detergent active system is a mixture of soap and a non-soap anionic detergent active, and optionally with the further inclusion of a nonionic detergent active material. Particularly preferred detergent active systems contain from 2 - 17% non-soap anionic detergent active, up to 8% nonionic detergent active, up to 8% soap and a ratio of nonionic to soap of from 3:1 to 1:3, most preferably from 2:1 to 1:2. As used herein, the term "soap" includes not only the usual alkali metal and alkaline earth metal salts of fatty acids, but also the organic salts which can be formed by complexing fatty acids with organic nitrogen-containing materials such as amines and derivatives thereof. Usually, the soap comprises salts of higher fatty acids containing from 8 to 24 carbon atoms, preferably from 10 to 20 carbon atoms in the molecule, or mixtures thereof. Preferred examples of soaps include sodium stearate, sodium palmitate, sodium salts of tallow, coconut oil and palm oil fatty acids and complexes between stearic and/or palmitic fatty acid and/or tallow and/or coconut oil and/or palm oil fatty acids with water-soluble alkanolamines such as ethanolamine, di- or triethanolamine, and 2,2-dimethyl ethanolamine and N-containing ring compounds such as morpholine, 2′-pyrrolidone and their methyl derivatives. Mixtures of soaps can also be employed. Particularly preferred are the sodium and potassium salts of the mixed fatty acids derived from coconut oil and tallow, that is sodium and potassium tallow and coconut soap. An essential ingredient of the composition is a water-soluble carbonate material as a builder. This is preferably sodium or potassium carbonate or a mixture thereof. We have however found particular advantages in the context of the present invention when the water-soluble carbonate material includes some bicarbonate salt. Thus, the carbonate salt may be fully neutralised but it is preferably partially neutralised, for example a sesquicarbonate may be used in partial replacement of the normal carbonate salt. A preferred carbonate to bicarbonate weight ratio is from 10:1 to 1:2, most preferably from 6:1 to 1:1. The amount of water-soluble carbonate material in the detergent composition can be varied widely, but the amount should be at least 5% by weight, such as from 10% to 40%, preferably 10% to 35% by weight. The amount of the water-soluble carbonate material is determined on an anhydrous basis, though the salts may be hydrated either before or when incorporated into the detergent composition. It should be noted that it may also be desirable to limit the carbonate content to a lower level within the range mentioned, so as to decrease the risk of internal damage following any accident ingestion, for example by children. Subject to the maximum 40% limit on the builder material in the compositions of the present invention, further builder materials may be present, although materials which act as seed crystal poisons are best avoided. Examples of such further builder materials referred to in the art include fatty acids, selected water-soluble soaps, alkyl malonates, alkenyl or alkyl succinates, sodium fatty acid sulphonates, alkali metal orthophosphates, polyacetates, carboxylates, polycarboxylates, succinates and zeolites or their amorphous equivalents. The composition necessarily contains a water-insoluble particulate carbonate material. This material must be capable of acting as a seed crystal for the precipitate which results from the reaction between the calcium hardness ions of the water and the water-soluble carbonate. Thus this water-insoluble particulate materials is a seed crystal for calcium carbonate, such as calcium carbonate itself. The water-insoluble particulate carbonate material must be finely divided, with a surface area of at least 10 m²/g, and preferably at least 15 m²/g. The particularly preferred material has surface area from 30-100 m²/g. Insoluble carbonate material with surface areas in excess of 100 m²/g may be used, if such materials are economically available. Surface area is measured by nitrogen absorption using the standard Bruauer, Emmet & Teller (BET) method. A suitable machine for carrying out this method is a Carlo Erba Sorpty 1750 (Registered Trade Mark) instrument operated according to the manufacturer's instructions. It is most preferred that the high surface area material be prepared in the absence of poisons, so as to retain its seed activity. The insoluble carbonate material will usually have an average particle size of less than 10 µm, as measured by sieve analysis, but may be granulated for ease of handling. When the insoluble carbonate material is calcium carbonate, any crystalline form thereof may be used or a mixture thereof, but calcite is preferred as aragonite and vaterite are less readily available commercially, and calcite is a little less soluble than aragonite or vaterite at most usual wash temperatures. When any aragonite or vaterite is used it is generally in admixture with calcite. In the following general description, the term 'calcite' is used to mean either calcite itself or any other suitable water-insoluble calcium carbonate seed material. The selected level of calcite in the overall composition depends on the specific surface area as described above. The amount of calcite used in the compositions should be from 10% to 60%, more preferably from 15% to 30%. A weight ratio of water soluble carbonate material to calcite of less than about 4:1 is preferred. A further essential component of the compositions of the present invention is a fabric softening clay material. This clay material should be a phyllosilicate clay with a 2:1 layer structure, the non-silicate layer being either dioctahedrally or trioctahedrally coordinated and includes the species Saponite, Hectorite, Montmorillonite or Beidellite. Other 2:1 clay minerals such as Talc, Vermiculite, Mica and Chlorite have been proved to be unsuitable for fabric softening as have been the unaltered minerals of the 1:1 layered clays of the Kaolin group. Other aluminosilicate materials which do not have a layer structure, such as zeolites are also unsuitable as fabric softening clay materials. Particularly suitable clay materials are the smectite clays described in detail in United States Patent Specification US 3 959 155 (MONTGOMERY et al assigned to THE PROCTER & GAMBLE COMPANY), especially smectite clays such as described in United States Patent Specification US 3 936 537 (BASKERVILLE). Other disclosures of suitable clay materials for fabric softening purposes include European patent specification EP 26528-A (PROCTER & GAMBLE LIMITED). The most preferred clay fabric softening materials include those materials of bentonitic origin, bentonites being primarily montmorillonite type clays together with various impurities, the level and nature of which depends on the source of the clay material. The level of fabric softening clay material in the compositions of the invention should be sufficient to provide the fabrics with a softening benefit. A level of up to 35% by weight of the composition is suitable, preferably from 8% to 15%, these percentages referring to the level of the clay mineral per se . Levels of clay raw material higher than this may be necessary when the raw material is derived from a particularly impure source. The weight ratio of the seed crystal to the clay is less than 1.8 to 1. If a higher ratio is used, such as 3.0 to 1, we have found that the fabric softening benefit obtained from the clay is insufficient. The detergent composition can optionally contain any of the conventional ingredients in the amounts in which such ingredients are normally employed in fabric washing detergent compositions. One such optional ingredient is an alkali metal silicate, particularly sodium neutral, alkaline, meta- or orthosilicate. A low level of silicate, for example 5-10% by weight, is usually advantageous in decreasing the corrosion of metal parts in fabric washing machines, and it may give processing benefits. If higher levels of silicate are used up to a practical maximum of 30%, for example from 10% to 20% by weight, there can be a more noticeable improvement in detergency, which may permit some decrease in the water-soluble carbonate material content. This effect appears to be particularly beneficial when the wash liquor is used in water with appreciable levels of magnesium hardness. The amount of silicate can also be used to some extent to control the equilibrium pH of the wash liquor, which is generally above 9, preferably 10-11 for an aqueous solution of the composition at the recommended concentration. Sodium silicate is commonly supplied in concentrated aqueous solution, but the amounts are calculated on an anhydrous basis. Examples of other optional ingredients include the lather boosters such as alkanolamides, particularly the monoethanolamides derived from palm kernel fatty acids and coconut fatty acids, lather depressants, oxygen-releasing bleaching agents such as sodium perborate and sodium percarbonate, peracid bleach precursors, chlorine-releasing bleaching agents such as trichloroisocyanuric acid, other fabric softening agents, inorganic salts such as sodium sulphate, and, usually present in very minor amounts, fluorescent agents, perfumes, enzymes such as proteases and amylases, germicides and colourants. The detergent compositions may be produced by any of the techniques commonly employed in the manufacture of fabric washing detergent compositions, including slurry-making and spray-drying processes. Thus, the composition may comprise spray-dried beads containing at least a part, such as all, of the detergent active system and the water-soluble carbonate, while the calcite or other seed crystal is added thereto as separate particles, which may be pre-granulated. The clay material may be included in the slurry for the spray-dried beads or added separately to the composition either as a powder or as a pre-granulated material. Alternatively when the composition contains sodium silicate, it may be prepared by granulating a carbonate/silicate powder with the seed crystal material, ideally in the presence of a liquid binder such as sucrose solution, as described in more detail in South African patent 87/8350 (Unilever PLC). The invention will now be described in further detail in the following non-limiting examples. In the examples, the following compositions were prepared by spray-drying some ingredients to form a base powder and then adding other ingredients thereto. Notes 1 - Dobane 112 (ex Shell Chemicals) which is sulphonated to form approximately a sodium benzene sulphonate in which the alkyl group contains from 10 to 15 carbon atoms. 2 - Dobanol 45-11 EO which is approximately a C 14/15 alcohol ethoxylated with 11 moles of ethylene oxide. 3 - Hardened tallow soap. 4 - Socal U3 (ex Solvay) having a nominal surface area of 100m²/g. 5 - RH412, a calcium bentonite from Morocco, ex English China Clays 6 - As the monohydrate. 7 - Having a Na₂O:SiO₂ ratio of 1:3.3 8 - A granule comprising a mixture of waxes, hydrocarbon oil and hydrophobed silica. * - Composition A is included for the purposes of comparison. "Dobane", "Dobanol", "Socal" are Registered Trade Marks. EXAMPLES 1 Composition A was tested in the following manner. A 2.5kg fabric load comprising a mixture of prewashed and preharshened terry cotton monitors were washed for 30 minutes at 40°C or 95°C in an automatic washing machine. The water hardness was 24°FH and the product dosage was 140g into 20 litres of wash liquor. A similar wash liquor was prepared containing the same amount of composition A together with 17g of clay, being therefore equivalent to a composition (B) containing about 12% clay. After each wash the monitors were line dried and washed again. After 5 such washes the softness of the monitors was determined by a panel of trained assessors. Results are expressed as the number of preferences - the higher the score the softer the cloth. The results were: These results demonstrate that at both wash temperatures after 5 washes product B, containing post-dosed clay, is rated softer than the otherwise identical product without clay. EXAMPLE 2 Compositions A and D were tested in the same manner as in Example 1 except that the wash load comprised naturally soiled articles, the wash temperature was 60°C and for each wash 70g of product was used for a pre-wash followed by 140g of product as a main wash. The water hardness was 40°FH and softness assessments were made after 2 and 6 washes. The results were: These results demonstrate the benefit of the invention, when the clay is included in the spray dried base powder. When composition D was modified by post-dosing the clay and the calcite and the modified composition was tested, it was found to be very similar in softness performance to composition D. EXAMPLE 3 Compositions G to J were tested in the same manner as Example 1 except that the wash temperature was 60°C and the product dosage was 7.7 g/l. In place of an automatic washing machine, a laboratory scale apparatus fitted with an impellor agitator was used, the fabric load consisting of pre-washed terry cotton monitors. Softness was assessed after 1 wash. The initial pH of the wash liquor was measured in each case. The results were: These results demonstrate the benefit of progressively replacing part of the carbonate salt with bicarbonate, and the consequential fall in the pH of the wash liquor. When compositions G and J were tested in the same way, either at 40°C or at 60°C and the fabric load included two different standard cotton detergency test cloths, and the observed % detergency results were: where Δ₉₅ is the confidence limit for a significant difference of 95% probability. It will be seen that although composition J exhibited the lower pH and was preferred in terms of softening, the observed detergency results are not significantly different. EXAMPLE 4 Compositions K to P were tested in the same manner as Example 3 and softness was assessed after 1 wash. The results were: These results show not only the benefit of adding bicarbonate to the compositions, but also that in the absence of bicarbonate there is a benefit for the inclusion of higher levels of soap and nonionic actives.

Claims: A detergent composition for washing and softening fabrics which is essentially free of phosphate builder and comprises: (i) from 2% to 40% by weight of a detergent active system comprising at least one non-soap detergent active material; (ii) from 5% to 40% by weight of builder material which comprises water-soluble carbonate in an amount which is at least 5% by weight of the composition; and (iii) from 10% to 60% by weight of a water-insoluble carbonate having a surface area of at least 10m²/g as calcium carbonate seed crystal; characterised in that the composition further comprises: (iv) up to 35% by weight of a fabric softening clay material; the weight ratio of the seed crystal to the clay material being less than 1.8:1. A composition according to Claim 1, wherein the water-soluble carbonate builder material comprises a mixture of an alkali metal carbonate salt and an alkali metal bicarbonate salt. A composition according to claim 1 or claim 2, wherein the detergent active system comprises non-soap anionic detergent active or a mixture of non-soap anionic detergent active with nonionic detergent active, the amount of non-soap anionic detergent active being greater than the amount of any nonionic detergent active. A composition according to any one of the preceding claims, wherein the detergent active system comprises a mixture of soap and a non-soap anionic detergent active material. A composition according to claim 4, wherein in that the detergent active system also comprises a nonionic detergent active material. A composition according to any one of the preceding claims, wherein at least a part of the detergent active system and the water soluble carbonate builder material is present in the form of spray-dried granules, the remaining ingredients, including at least a part of the seed crystal, being present in the form of separate particles.

Inventors: LLOYD, JOHN
Applicants: UNILEVER N.V., UNILEVER PLC
Application year: 1988
Main classification: C11D3
IPC codes: D06M11, C11D10, C11D3