Particulate detergent compositions

Abstract: A particulate high-density detergent composition having excellent flow properties comprises 15 to 50 wt% of a high-performance surfactant system - selected ethoxylated alcohol nonionic surfactant plus optionally a minor amount of primary alkyl sulphate - and from 20 to 60 wt% of zeolite. The ethoxylated nonionic surfactant preferably has a peaked ethoxylation distribution, and the zeolite may advantageously be maximum aluminium zeolite P. The composition is preferably prepared by an agglomeration process utilising a high-speed mixer/granulator.

Description: TECHNICAL FIELD The present invention is concerned with particulate detergent compositions that combine exceptionally good cleaning performance with high bulk density and excellent powder properties. The compositions contain a high level of high-performance organic surfactant - selected ethoxylated alcohol optionally plus a minor amount of alkyl sulphate - and zeolite detergency builder, and are preferably prepared by an agglomeration process using a high-speed mixer/granulator. BACKGROUND Recently the trend in detergent powders has been towards increased bulk density, for example, above 600 g/l. These high-density or "concentrated" powders have been prepared by various processes, some involving post-densification of a spray-dried powder, and others based on dry mixing, agglomeration or other wholly non-tower processes. The move to higher densities, and thus inherently less porous particles, has made the incorporation of high levels of mobile organic ingredients without loss of powder flow properties more difficult. However, it has become highly desirable to improve detergency performance by incorporating higher levels of surfactant, and by using surfactants having the greatest possible effectiveness against oily and fatty soils. One class of such surfactants consists of ethoxylated alcohols having a relatively low degree of ethoxylation, and those are generally mobile liquids at ambient temperature. In view of increasing environmental awareness, it has also become desirable to use alkyl sulphates in preference to the linear alkylbenzene sulphonates traditionally used in laundry detergents. Alkyl sulphates are readily biodegradable and can be obtained from renewable sources such as coconut and palm oil. However, they are generally more difficult to process into high quality detergent powders than are alkylbenzene sulphonates. Nonionic surfactants, alkyl sulphates and mixtures of the two have been found to provide highly efficient detergency, but because of their mobility are difficult to incorporate, even at moderate levels, into free-flowing powders that will disperse in the wash liquor. When higher proportions of these surfactants are required in order to push detergency performance to ever higher levels, these difficulties would be expected to increase, and to be exacerbated even further in the highly concentrated, dense powders currently favoured by the consumer and the detergents industry. The present inventors, however, have succeeded in formulating high bulk density free-flowing detergent powders combining excellent performance with good powder properties and dispersibility, despite their containing relatively high levels of high-performance mobile surfactants. The powders of the invention contain relatively high levels of zeolite builder, and may be prepared by a granulation process in a high-speed mixer/granulator. Especially good powder properties may be obtained by use of a novel zeolite P as the builder; and especially good detergency may be obtained by use of selected nonionic surfactants. PRIOR ART EP 265 203A (Unilever) discloses a surfactant blend mobile at a temperature within the range of from 20 to 80°C, comprising from 20 to 80 wt% of alkylbenzene sulphonate or alkyl sulphate, from 80 to 20 wt% of ethoxylated nonionic surfactant and from 0-10 wt% water. The surfactant blend may be sprayed on to an absorbent particulate solid material, for example, spray-dried polymer-modified Burkeite, to give free-flowing detergent powder containing up to about 25 wt% of surfactant. EP 436 240A (Unilever) discloses a similar mobile surfactant blend additionally containing a fatty acid soap. When sprayed onto an absorbent solid material, this blend gives powders having improved flow and dispensing properties. GB 1 462 134 (Procter & Gamble/Collins) discloses linear or predominantly linear ethoxylated primary alcohols of closely defined chain length, chain length distribution, ethylene oxide content, ethoxylation distribution and free alcohol content. These materials give improved oily soil detergency as compared with conventional commercially available materials. EP 133 715A (Union Carbide) discloses an alkoxylation product mixture having an especially highly peaked distribution of alkoxylation species, in which a single prevalent alkoxylation species constitutes 20 to 40 wt% and the amounts of species differing substantially from the prevalent species are strictly limited. EP 384 070A (Unilever) discloses the use as a detergency builder of zeolite P having a silicon to aluminium ratio not greater than 1.33 (zeolite MAP). This zeolite has been found to be a more effective and rapid binder of calcium ions than is conventional zeolite 4A. Our copending European Patent Application No. 92 305 590.9, filed on 18 June 1992, claiming a priority date of 25 June 1991, and to be published in December 1992, discloses free-flowing particulate detergent compositions based on zeolite MAP and containing high levels of liquid, viscous-liquid, oily or waxy components (for example, nonionic surfactants) while displaying excellent flow properties. Example K of that application discloses a high bulk density powder consisting of 50 wt% zeolite 4A, 23.4 wt% sodium carbonate, and 26.6 wt% of the nonionic surfactant Synperonic A3 (synthetic C 12-15 alcohol having an average degree of ethoxylation of 3); and Example 7 discloses a high bulk density powder consisting of 56.6 wt% zeolite MAP, 13.3 wt% sodium carbonate, and 30.1 wt% Synperonic A3. These compositions are specifically disclaimed in the present application. Our copending British Patent Application No. 91 25035.7 filed on 26 November 1991, from which the present application claims priority, claims a process for preparing a granular detergent composition having a bulk density of at least 650 g/l, which comprises treating a particulate starting material in a high speed mixer/densifier in the presence of a liquid surfactant composition comprising an alkyl sulphate (20-80 wt%), an ethoxylated nonionic surfactant (80-20 wt%) and water (0-20 wt%). DEFINITION OF THE INVENTION The present invention provides a particulate detergent composition having a bulk density of at least 650 g/l, preferably at least 700 g/l and advantageously at least 800 g/l, comprising: (a) from 15 to 50 wt% of a surfactant system consisting essentially of: (i) 60 to 100 wt% of ethoxylated nonionic surfactant which is a primary C 8 -C 18 alcohol having an average degree of ethoxylation not exceeding 6.5 based on the total weight of the surfactant system, (ii) 0 to 40 wt% of primary C 8 -C 18 alkyl sulphate based on the total weight of the surfactant system; (b) from 20 to 60 wt% of zeolite; (c) optionally other detergent ingredients to 100 wt%; the composition being prepared by a wholly non-tower route by granulating the zeolite and surfactants in a high speed mixer/granulator. DETAILED DESCRIPTION OF THE INVENTION The particulate detergent composition of the invention is characterised by an especially high level of a high-performance organic surfactant system. At least 15 wt% of the composition is constituted by the surfactant, and as much as 50 wt% may be present. Compositions may advantageously contain at least 20 wt%, more advantageously at least 25 wt%, of the surfactant system. The surfactant system consists essentially of ethoxylated alcohol having a relatively low degree of ethoxylation, optionally with a minor proportion (not exceeding 40 wt% of the surfactant system) of primary alkyl sulphate. The proportion of primary alkyl sulphate preferably does not exceed 35 wt% (of the surfactant system), and more preferably does not exceed 30 wt% of the surfactant system. Preferred proportions of alkyl sulphate in the surfactant system are from 0.1 to 35 wt%, more preferably from 5 to 35 wt%, and advantageously from 10 to 30 wt%. Also preferred are surfactant systems in which the proportion of alkyl sulphate does not exceed 15 wt%, for example, from 0.1 to 15 wt%, preferably from 0.1 to 10 wt%. The ethoxylated alcohol nonionic surfactant The ethoxylated alcohol nonionic surfactant employed in the detergent compositions of the present invention has a relatively low degree of ethoxylation, not exceeding 6.5. When primary alkyl sulphate is absent, the average degree of ethoxylation of the nonionic surfactant is preferably at least 4, but it may be lower, for example, from 3 to 4, when primary alkyl sulphate is present. Accordingly, when primary alkyl sulphate is present, the ethoxylated alcohol preferably has an average degree of ethoxylation within the range of from 3 to 6.5. Whether or not alkyl sulphate is present, the preferred range for the average degree of ethoxylation of the nonionic surfactant is within the range of from 4 to 6.5, more preferably from 4 to 6 and most preferably from 4 to 5.5. A mixture of differently ethoxylated materials may be used, provided that the overall degree of ethoxylation meets the stated requirements. The HLB value of the nonionic surfactant preferably does not exceed 11.0, and more preferably does not exceed 10.5. Desirably the HLB value is within the range of from 9.5 to 10.5. The chain length of the ethoxylated alcohol may generally range from C 8 to C 18 , preferably from C 12 to C 16 ; an average chain length of C 12-15 is preferred. Especially preferred is ethoxylated alcohol consisting wholly or predominantly of C 12 -C 14 material. The ethoxylated alcohol is preferably primary, but secondary alcohol ethoxylates could in principle be used. The alcohol is preferably wholly or predominantly straight-chain. Suitable alcohols are vegetable-derived, for example, coconut, which is the most preferred material. Among the synthetic alcohols, Ziegler alcohols are preferred to oxo-based alcohols. According to a preferred embodiment of the invention, giving exceptionally good oily soil detergency, the ethoxylated alcohol (which of course is always a mixture of species having different numbers of ethylene oxide units) is a "narrow range" material having a distribution of ethoxylated species that is more highly peaked about a single prevalent value than is the case in conventional commercial nonionic surfactants. The content of unethoxylated material is also generally lower, and may be reduced further by so-called "stripping". "Narrow range" alkoxylates are described and claimed, for example, in EP 133 715A (Union Carbide) mentioned previously. These are especially highly peaked mixtures having an average alkoxylation number of at least 4, in which at least one alkoxylation species (the "prevalent species") constitutes about 20 to 40 wt% of the mixture; the proportion of species having 3 or more alkoxylation units above the mean is less than 12 wt%; and the species having 1 more and 1 less alkoxylation unit that the mean are each present in a weight ratio to the prevalent species of 0.6:1 to 1:1. Preferred product mixtures contain from 80 to 95 wt% of alkoxylation species having alkoxylation numbers within plus or minus 2 of the mean. However, the term "narrow range" as used in the present specification also covers materials that are not so highly peaked as to meet the requirements of the Union Carbide patent claims, but yet are substantially more peaked than, for example, the commercially available ICI "Synperonic" (Trade Mark) ethoxylated alcohols. The term therefore is defined herein as covering any ethoxylated alcohol product in which a single ethoxylation species constitutes 13 wt% or more, preerably 15 wt% or more, of the product. Conventional ethoxylates contain no more than about 10 wt% of any one ethoxylation species. The prevalent species preferably contains 4 or 5 ethoxylation units. Preferred "narrow range" ethoxylated alcohol used in the compositions of the invention may have any one or more of the following characteristics: at least 20 wt% of the ethoxylated alcohol may be constituted by a single ethoxylation species; at least one ethoxylation species (hereinafter the prevalent species) may constitute from 20 to 40 wt% of the ethoxylated alcohol, the proportion of species having 3 or more ethoxylation units above the mean being less than 12 wt%, and the species having 1 more and 1 less ethoxylation unit than the mean each being present in a weight ratio to the prevalent species of 0.6:1 to 1:1; from 80 to 95 wt% of the ethoxylated alcohol may be constituted by ethoxylation species having ethoxylation numbers within plus or minus 2 of the mean. Differently defined "narrow range" ethoxylates are also described in GB 1 462 132 (Procter & Gamble/ Collins): these are materials having an average degree of ethoxylation between 3.5 and 6.5, the amount of material having a degree of ethoxylation within the 2-7EO range being at least 63 wt%, and the amount of free alcohol not exceeding 5 wt%. These materials are also suitable for use in the compositions of the present invention. The following table shows the ethoxylation distribution of some commercially available coconut-based ethoxylates, both narrow-range (NRE7, NRE5 etc), and broad-range (E7, E3), the figures indicating the nominal average degree of ethoxylation in each case. It is within the scope of the invention to achieve the preferred value of 4 to 6.5 for the average degree of ethoxylation by using a mixture of commercial materials, eg a (nominal) 3EO ethoxylate and a (nominal) 7EO ethoxylate, in appropriate proportions. However, it is especially preferred to use a single commercial material, and the materials designated NRE5, NRE4.6 and NRE4.2 are especially preferred, NRE4.2 being particularly favoured. It is especially preferred, in accordance with the invention, to use wholly or predominantly straight-chain ethoxylated alcohol that is also "narrow range". It may also be desirable to use a "narrow range" ethoxylate having a narrower distribution of chain length than do conventional commercial nonionic surfactants. For example, the nonionic surfactants described in the aforementioned GB 1 462 134 (Procter & Gamble/Collins) are such that at least 65 wt% of the material has a chain length within ± 1 carbon atom of the mean value. "Narrow range" ethoxylates are now commercially available in Europe and North America, for example, from Vista, Union Carbide and Hoechst. The primary alkyl sulphate The primary alcohol sulphate (PAS) that may optionally be present, constituting up to 40 wt% of the surfactant system, may have a chain length in the range of C 8 -C 18 , preferably C 12 -C 16 , with a mean value preferably in the C 12-15 range. Especially preferred is PAS consisting wholly or predominantly of C 12 -C 14 material. If desired, mixtures of different chain lengths may be used as described and claimed in EP 342 917A (Unilever). As for the ethoxylated alcohol, predominantly or wholly straight-chain material, is preferred. PAS of vegetable origin, and more especially PAS from coconut oil (cocoPAS) is especially preferred. However, it is also within the scope of the invention to use branched PAS as described and claimed in EP 439 316A (Unilever). The PAS is present in the form of the sodium or potassium salt, the sodium salt generally being preferred. The zeolite detergency builder The amount of zeolite builder in the compositions of the invention may range from 20 to 60 wt%, usually from 25 to 55 wt% and suitably, in a heavy duty detergent composition, from 25 to 48 wt%. Depending on the amount and composition of the surfactant system, the zeolite may be the commercially available zeolite 4A now widely used in laundry detergent powders. For example, the use of zeolite 4A can give powders having satisfactory flow properties when 17 wt% of surfactant consisting of 30 wt% PAS and 70 wt% nonionic surfactant is present. However, as the total surfactant loading and/or the proportion of nonionic surfactant is or are increased, the more difficult it is to obtain acceptable powder flow properties. According to a preferred embodiment of the invention, the zeolite builder incorporated in the compositions of the invention is zeolite MAP as described and claimed in EP 384 070A (Unilever Case T3047). Zeolite MAP is defined as an alkali metal aluminosilicate of the zeolite P type having a silicon to aluminium ratio not exceeding 1.33, preferably within the range of from 0.90 to 1.33, and more preferably within the range of from 0.90 to 1.20. Especially preferred is zeolite MAP having a silicon to aluminium ratio not exceeding 1.07. The calcium binding capacity of zeolite MAP is generally at least 150 mg CaO per g of anhydrous material. In the present invention, the use of zeolite MAP has another advantage quite independent of its greater building efficacy: it enables more higher total surfactant levels, and more nonionic-rich surfactant systems, to be used without loss of powder flow properties. Preferred zeolite MAP for use in the present invention is especially finely divided and has a d 50 (as defined below) within the range of from 0.1 to 5.0 microns, more preferably from 0.4 to 2.0 microns and most preferably from 0.4 to 1.0 microns. The quantity "d 50 " indicates that 50 wt% of the particles have a diameter smaller than that figure, and there are corresponding quantities "d 80 ", "d 90 " etc. Especially preferred materials have a d 90 below 3 microns as well as a d 50 below 1 micron. Sodium carbonate The compositions in accordance with the invention may contain sodium carbonate, to increase detergency and to ease processing. Sodium carbonate may generally be present in amounts ranging from 1 to 60 wt%, preferably from 2 to 40 wt%, and most suitably from 2 to 13 wt%. The optional powder structurant Powder flow may be improved by the incorporation of a small amount of a powder structurant, for example, a fatty acid (or fatty acid soap), a sugar, an acrylate or acrylate/maleate polymer, or sodium silicate. The preferred powder structurant is fatty acid soap, suitably present in an amount of from 1 to 5 wt%. As will be discussed below in the context of processing, this is preferably incorporated as the free acid and neutralised in situ. Powder flow properties The compositions of the invention are characterised by excellent flow properties, despite the high content of mobile high-performance organic surfactant. For the purposes of the present invention, powder flow is defined in terms of the dynamic flow rate, in ml/s, measured by means of the following procedure. The apparatus used consists of a cylindrical glass tube having an internal diameter of 35 mm and a length of 600 mm. The tube is securely clamped in a position such that its longitudinal axis is vertical. Its lower end is terminated by means of a smooth cone of polyvinyl chloride having an internal angle of 15° and a lower outlet orifice of diameter 225 mm. A first beam sensor is positioned 150 mm above the outlet, and a second beam sensor is positioned 250 mm above the first sensor. To determine the dynamic flow rate of a powder sample, the outlet orifice is temporarily closed, for example, by covering with a piece of card, and powder is poured through a funnel into the top of the cylinder until the powder level is about 10 cm higher than the upper sensor; a spacer between the funnel and the tube ensures that filling is uniform. The outlet is then opened and the time t (seconds) taken for the powder level to fall from the upper sensor to the lower sensor is measured electronically. The measurement is normally repeated two or three times and an average value taken. If V is the volume (ml) of the tube between the upper and lower sensors, the dynamic flow rate DFR (ml/s) is given by the following equation: DFR = V t ml/s The averaging and calculation are carried out electronically and a direct read-out of the DFR value obtained. Compositions and components of the present invention generally have dynamic flow rates of at least 90 ml/s, preferably at least 100 ml/s. Other optional ingredients Fully formulated laundry detergent compositions in accordance with the present invention may additionally contain any suitable ingredients normally encountered, for example, inorganic salts such as sodium silicate or sodium sulphate; organic salts such as sodium citrate; antiredeposition aids such as cellulose derivatives and acrylate or acrylate/maleate polymers; fluorescers; bleaches, bleach precursors and bleach stabilisers; proteolytic and lipolytic enzymes; dyes; coloured speckles; perfumes; foam controllers; fabric softening compounds. Preparation of the detergent compositions The compositions of the invention may advantageously be prepared by granulating the zeolite and surfactants in a high-speed mixer/granulator. If the surfactant system includes PAS, that may be incorporated either in salt form (generally as an aqueous paste), or as the free acid (for neutralisation in situ). An especially preferred process includes the steps of: (i) preparing the surfactant system in the form of a homogeneous mobile liquid blend, and (ii) agglomerating the mobile liquid surfactant blend with the zeolite and other solids present in a high-speed mixer/granulator. If no PAS is to be present, the surfactant system is simply an ethoxylated alcohol (mixture) which will already take the form of a homogeneous mobile liquid blend. If PAS is to be present, the homogeneous mobile liquid blend may be prepared by mixing PAS paste with the nonionic surfactant. Alternatively, the nonionic may be admixed during the neutralisation of PAS acid by alkali, for example in a loop reactor, as described and claimed in EP 507 402A (Unilever) filed on 31 March 1992 and published on 7 October 1992. The high-speed mixer/granulator, also known as a high-speed mixer/densifier, may be a batch machine such as the Fukae (Trade Mark) FS, or a continuous machine such as the Lödige (Trade Mark) Recycler CB30. The process is described in more detail, and claimed, in our copending British Patent Application No. 91 25035.7 (Unilever) filed on 26 November 1991, from which the present application claims priority. The process allows the incorporation of high levels of surfactant without loss of powder flow properties, especially when the zeolite component of the composition is zeolite MAP and/or when soap is present as a structurant. If soap is to be included as a structurant, this is preferably incorporated in the mobile surfactant blend, either as such, or as the corresponding fatty acid (together with a suitable amount of alkali) for neutralisation in situ. The other optional ingredients mentioned above may be incorporated at any suitable stage in the process. In accordance with normal detergent powder manufacturing practice, bleach ingredients (bleaches, bleach precursors and bleach stabilisers), proteolytic and lipolytic enzymes, coloured speckles, perfumes and foam control granules are most suitably admixed (postdosed) to the dense granular product after it has left the high-speed mixer/granulator. Of course the compositions of the invention may also be prepared by other processes, involving spray-drying or non-tower technology or combinations of the two. The invention is further illustrated by the following non-limiting Examples, in which parts and percentages are by weight unless otherwise stated. EXAMPLES The abbreviations used in the Examples indicate the following materials: CocoPAS Linear C 12-14 primary alcohol sulphate (sodium salt) derived from coconut oil, ex Philippine Refining Co. E7(s) C 13-15 oxo alcohol 7EO, not "narrow range": Synperonic (Trade Mark) A7 ex ICI E3(s) C 13-15 oxo alcohol 3EO, not "narrow range": Synperonic (Trade Mark) A3 ex ICI E7 Coconut alcohol 7EO, not "narrow range" E3 Coconut alcohol 3EO, not "narrow range" NRE7 (s) C 12-14 Ziegler linear "narrow range" alcohol 7EO: Alfonic (Trade Mark) 7 ex Vista NRE3(s) C 12-14 Ziegler linear "narrow range" alcohol 3EO: Alfonic (Trade Mark) 3 ex Vista NRE7 Coconut alcohol 7EO, "narrow range" NRE5 Coconut alcohol 5EO, "narrow range" NRE4.6 Coconut alcohol 4.6EO, "narrow range" NRE4.2 Coconut alcohol 4.2EO, "narrow range" NRE3 Coconut alcohol 3EO, "narrow range" Zeolite 4A Wessalith (Trade Mark) P powder ex Degussa Zeolite MAP Zeolite MAP prepared by a method similar to that described in Examples 1 to 3 of EP 384 070A (Unilever); Si:Al ratio 1.07. Polymer Acrylic/maleic copolymer: Sokalan (Trade Mark) CP5 ex BASF LAS Linear alkylbenzene sulphonate, sodium salt Perborate mono Sodium perborate monohydrate TAED Tetraacetylethylenediamine, as 83 wt% granules EDTMP Ethylenediaminetetramethylenephosphonic acid, calcium salt: Dequest (Trade Mark) 2041 or 2047 ex Monsanto (34 wt% active) Antifoam Antifoam granules in accordance with EP 266 863B (Unilever) EXAMPLES 1 TO 10 - DETERGENCY Examples 1 to 4 Detergent compositions were prepared to the following general formulation: parts % Surfactant system (see below) 17 20.11 Zeolite 4A 32 37.86 Polymer 4 4.73 Carbonate 14.5 17.16 Silicate 0.5 0.59 Metaborate 16.5 19.53 84.50 100.00 The surfactant systems were made up as follows (wt%): Example CocoPAS E7(s) E3(s) NRE7(s) NRE3(s) 1 30 30 40 - - 2 30 - - 30 40 3 10 40 50 - - 4 10 - - 40 50 Both mixtures of 30 parts of 7EO nonionic surfactant and 40 parts of 3EO nonionic surfactant had an average EO number of 4.7 and an HLB value of 10.1. The percentage of the predominant ethoxylation species (4EO) in the NRE mix was estimated to be 14 wt%. Detergencies (removal of radio-labelled triolein soil from polyester) were compared in the tergotometer using a 5 g/l product concentration, 24° (French) hard water and a wash temperature of 23°C. The results were as follows: Example % triolein removal 1 42.2 2 47.4 3 59.8 4 61.6 Comparison of the results for Comparative Example A, Example 1 and Example 3 shows how increasing the proportion of nonionic surfactant at the expense of PAS increases detergency: while comparison of the results for Examples 1 and 2, and for Examples 3 and 4, shows the detergency benefit obtained by changing to "narrow range" ethoxylated alcohol. The outstandingly good result for Example 4 shows the benefit of combining these two measures. Examples 5 to 7 A further detergency comparison was carried out, using test cloths carrying a number of different soils. This experiment was carried out using a Miele (Trade Mark) computer-controlled washing machine, using a product concentration of 5 g/l, and a 30-minute wash at 20°C in 26° (French) hard water. The compositions had the following general formulation: parts % Surfactant system (see below) 17.0 19.50 Zeolite 4A 30.5 35.00 Sodium carbonate 12.77 14.65 Sodium silicate 0.5 0.57 Sodium perborate monohydrate 16.25 18.65 TAED (83% granules) 7.25 8.32 EDTMP 0.37 0.42 Antifoam granules 2.50 2.87 87.14 100.00 The surfactant systems were made up as follows (wt%): Example CocoPAS E7(s) E3(s) NRE7(s) NRE3(s) 5 30 30 40 - - 6 30 - - 30 40 7 10 - - 40 50 The results (expressed as reflectance changes at 460 nm) were as follows: Test cloth 1 : kaolin and wool fat on polyester/cotton (WFK 10C) Reflectance change (delta R 460 ) Example 5 10.9 Example 6 11.8 Example 7 12.4 Test cloth 2 : kaolin and wool fat on polyester/cotton (WFK 30C) Reflectance change (delta R 460 ) Example 5 21.4 Example 6 24.5 Example 7 27.5 Test cloth 3 : kaolin and sebum on cotton (WFK 10D) Reflectance change (delta R 460 ) Example 5 16.5 Example 6 17.4 Example 7 18.8 Test cloth 4 : kaolin and sebum on polyester (WFK 30D) Reflectance change (delta R 460 ) Example 5 18.7 Example 6 21.5 Example 7 25.1 Example 8 Using the same tergotometer procedure as in Examples 1 to 4, the detergencies of various surfactant mixtures containing different ethoxylated coconut alcohols were compared. In each case the compositions were as given in Example 1, and the surfactant systems consisted of 30 wt% cocoPAS, and 70 wt% ethoxylated alcohol. The ethoxylated alcohol component was made up (i) by mixing E7 and E3 (broad range) in varying proportions, or (ii) by mixing NRE7 and NRE3 (narrow range) in varying proportions, or (iii) by use of a single narrow range ethoxylate. The true degrees of ethoxylation will be recognised from the Table given earlier in this specification. Detergencies (% removal of radio-labelled triolein from polyester) as a function of degree of ethoxylation and starting ethoxylated alcohol are shown in the following Table. (i) (ii) (iii) EO (average) E7 + E3 NRE7 + NRE3 Single NRE 6.88 9.9 (E7) 5.96 14.1 (NRE7) 5.90 15.7 5.22 18.4 5.20 25.1 (NRE5) 5.17 21.0 4.94 21.2 4.86 30.7 (NRE4.6) 4.70 23.3 4.66 26.4 4.49 31.1 4.27 35.7 (NRE4.2) 3.96 27.3 3.75 35.5 3.01 36.4 (NRE3) 3.00 28.5 (E3) These results illustrate the advantage of average degrees of ethoxylation of 6 or below; the improvements obtained by moving to narrow range ethoxylates; and the especial benefits of using a single, narrow range material, in particular NRE4.2. Example 9 The procedure of Example 8 was repeated using a series of compositions having a more nonionic-rich surfactant system: 10 wt% cocoPAS and 90 wt% ethoxylated alcohol. The results are shown in the following Table. (i) (ii) (iii) EO (average) E7 + E3 NRE7 + NRE3 Single NRE 6.88 22.6 (E7) 5.96 34.3 (NRE7) 5.20 44.1 45.5 (NRE5) 5.17 35.3 4.94 35.5 51.5 (NRE4.6) 4.70 36.1 4.66 44.5 4.49 43.0 4.31 43.1 4.27 53.5 (NRE4.2) 3.75 44.1 3.01 35.4 (NRE3) 3.00 37.2 (E3) Again the benefits of using narrow range ethoxylates, especially single materials, are apparent. Example 10 The procedure of Examples 8 and 9 was repeated using a series of compositions in which the surfactant system consisted wholly of ethoxylated nonionic surfactant. The results are shown in the following Table. (i) (ii) (iii) EO (average) E7 + E3 NRE7 + NRE3 Single NRE 6.88 33.1 (E7) 5.96 42.9 (NRE7) 5.90 43.5 5.33 45.7 5.22 49.6 5.20 53.9 (NRE5) 4.94 47.6 4.86 55.5 (NRE4.6) 4.55 44.5 4.49 55.3 4.27 59.4 (NRE4.2) 4.19 55.9 3.96 38.5 3.75 51.2 3.01 12.8 (NRE3) 3.00 12.5 (E3) These results show a similar pattern to those shown by the results of Examples 8 and 9, and also illustrate clearly the substantial fall in detergency at average degrees of ethoxylation below 4 when no PAS is present. EXAMPLES 11 TO 32 - POWDER PROPERTIES Examples 11 and 12, Comparative Example A Detergent base powders of high bulk density, consisting of the surfactant system, zeolite and (in some cases) sodium carbonate, were prepared by agglomeration in a Fukae FS100 batch high-speed mixer/granulator. These powders are not intended as fully formulated detergent compositions, but are readily converted to such compositions by admixture (postdosing) of other components such as bleach ingredients, enzymes, lather control granules and perfume. The surfactant system was as follows: 30 wt% cocoPAS 30 wt% E7(s) 40 wt% E3(s) The compositions, in parts by weight and percentages, are shown below. A 11 12 Surfactant 17 (38.64) 17 (31.48) 17 (40.48) Zeolite 4A 27 (61.36) 27 (50.00) - Zeolite MAP - - 25 (59.52) Carbonate - 10 (18.52) - 44 (100.00) 54 (100.00) 42 (100.00) A homogeneous liquid blend of the surfactants was prepared by neutralising PAS acid with sodium hydroxide solution in a loop reactor in the presence of the nonionic surfactants. Zeolite and (where present) sodium carbonate were dosed into the Fukae mixer, the liquid surfactant blend added and the mixture granulated. The granular product was then dried using a fluidised bed. In the case of Comparative Example A it proved impossible to obtain a granular product; the mixture formed a solid mass. The addition of 10 parts of sodium carbonate (Example 11) enabled a granular product to be prepared. With zeolite MAP (Example 12), at a slightly lower level, the same amount (in parts - actually a slightly higher percentage loading) of the surfactant system could be incorporated without the need for sodium carbonate, and a free-flowing granular product was obtained. Comparative Examples B to E Further attempts to prepare base powders containing zeolite 4A with differing amounts of surfactant (the same system as in Examples A, 11, and 12) and carbonate were unsuccessful: Compositions in parts by weight B C D E Surfactant 13 15.3 17.2 18.5 Zeolite 4A 27 27 27 27 Carbonate - 5 10 15 40 47.3 54.2 60.5 Compositions in percentages B C D E Surfactant 32.50 32.35 31.73 30.58 Zeolite 4A 67.50 57.08 49.82 44.63 Carbonate - 10.57 18.45 24.79 Composition B produced a solid mass, while Compositions C, D and E initially produced free-flowing powders which, however, lost their flow on drying. Examples 12 to 15 An experiment similar to that of Comparative Examples B to E, but using zeolite MAP, gave powders having good flow properties, even at substantially higher surfactant contents. The compositions and powder properties are shown below. 12 13 14 15 Compositions in Part by weight Surfactant 17 18.4 19.6 20.8 Zeolite MAP 25 25 25 25 Carbonate - 4.4 8.9 13.9 42 47.8 53.5 59.7 Compositions in percentages Surfactant 40.48 38.49 36.64 34.84 Zeolite MAP 59.52 52.30 46.73 41.88 Carbonate - 9.21 16.64 23.28 Powder properties Bulk density (g/l) 794 817 829 867 DFR (ml/s) 100 93 56 72 Examples 16 and 17 Compositions similar to those of Comparative Examples B to E were prepared, but this time fatty acid soap was present. The method of preparation of these powders was slightly different from that used in previous Examples. A homogeneous mobile blend was prepared by mixing PAS in sodium salt form (70 wt%), fatty acid, sufficient sodium hydroxide solution to neutralise the fatty acid, and the nonionic surfactants. Ingredients were dosed into the Fukae mixer in the order zeolite, carbonate, surfactant blend, granulation/densification was carried out as in previous Examples, and the products were finally dried using a fluidised bed. Powders having excellent flow properties were obtained. Compositions 16 17 parts % parts % Surfactant 17 25.95 17 29.18 Zeolite 4A 32 48.85 32 54.94 Carbonate 14.5 22.14 7.25 12.45 Soap 2 3.05 2 3.43 65.5 100.00 58.25 100.00 Powder properties 16 17 Bulk density (g/l) 918 872 DFR (ml/s) 122 143 These Examples, when compared to Comparative Examples C to F, show that the inclusion of fatty acid soap made it possible to produce good high density powders from formulations unprocessable in its absence. Examples 18 and 19 Compositions similar to those of Examples 16 and 17 were prepared, by the same method, but using zeolite MAP instead of zeolite 4A. Compositions 18 19 parts % parts % Surfactant 17 25.95 17 29.18 Zeolite MAP 32 48.85 32 54.94 Carbonate 14.5 22.14 7.25 12.45 Soap 2 3.05 2 3.43 65.5 100.00 58.25 100.00 Powder properties 18 19 Bulk density (g/l) 980 959 DFR (ml/s) 131 143 Comparison of these Examples with Examples 12 to 15 shows that the inclusion of soap improved flow, but when zeolite MAP was used it was not essential in order to obtain acceptable powders. Examples 20 and 21, Comparative Examples F and G Detergent base powders generally as described in Examples 11, 12 and A were prepared using a different surfactant system: 10 wt% cocoPAS 40 wt% E7(s) 50 wt% E3(s) The surfactant system was prepared as a homogeneous mobile blend by the method described in Examples 11, 12 and A, and the other process steps were also carried out as in those Examples. Compositions in parts by weight F 20 G 21 Surfactant 17 17 17 17 Zeolite 4A 27 27 - - Zeolite MAP - - 25 25 Carbonate - 25 - 15 44 69 42 57 Compositions in percentages F 20 G 21 Surfactant 38.64 24.64 40.48 29.82 Zeolite 4A 61.36 39.13 - - Zeolite MAP - - 59.52 43.86 Carbonate - 36.23 - 26.32 In the case of Comparative Examples F and G it proved impossible to obtain a granular product; both mixture formed a solid mass. The addition of 25 parts of sodium carbonate to the zeolite 4A-based composition (Example 20) was required to enable a granular product to be prepared. With zeolite MAP (Example 21), only 15 parts of sodium carbonate were required. Examples 22 and 23, Comparative Example H Compositions similar to those of Examples 18 and 19 were prepared, but containing higher levels of zeolite. Compositions in parts by weight H 22 23 Surfactant 17 17 17 Zeolite 4A 32 32 - Zeolite MAP - - 32 Carbonate - 10 - 49 59 49 Compositions in percentages H 22 23 Surfactant 34.69 28.81 34.69 Zeolite 4A 65.31 54.24 - Zeolite MAP - - 65.31 Carbonate - 16.95 - Composition H would not give a granular product: 10 parts of sodium carbonate were required to produce a processable formulation. With zeolite MAP at this level, however, no carbonate was required despite the high percentage level of surfactant in this composition (Example 23). Example 24, Comparative Examples J and K Formulations based on zeolite 4A, with and without soap, were prepared using the surfactant system of Examples 20 to 22. The fatty acid soap was incorporated by mixing fatty acid and an equivalent amount of sodium hydroxide solution into the surfactant blend (prepared as described in Example 11) before addition of the blend to the Fukae mixer. J K 24 Compositions in parts by weight Surfactant 17 17 17 Zeolite 4A 32 32 32 Carbonate 14.5 14.5 14.5 Soap - 2 4 63.5 65.5 67.5 Compositions in percentages Surfactant 26.77 25.95 25.19 Zeolite 4A 50.39 48.85 47.41 Carbonate 22.83 22.14 21.48 Soap - 3.05 5.93 Composition J gave a non-flowing product both before and after drying, while Composition K initially gave a good product but lost its flow on drying. A larger amount of soap (Example 24) gave an excellent powder having a bulk density of 920 g/l and a dynamic flow rate of 109 ml/s. Examples 25 and 26 Compositions similar to those of Examples 24 and J but containing zeolite MAP and a higher level of surfactant were prepared. Compositions 25 26 parts % parts % Surfactant 20.5 30.60 20.5 29.71 Zeolite MAP 32 47.76 32 46.37 Carbonate 14.5 21.64 14.5 21.01 Soap - - 2 2.90 67.0 69.0 Powder properties 25 26 Bulk sensity (g/l) 928 898 DFR (ml/s) 115 114 Example 27, Comparative Example L Compositions similar to those of Examples J and K were prepared using a different surfactant system: 40 wt% E7(s) 60 wt% E3(s) Compositions L 27 parts % parts % Surfactant 17 26.77 17 25.95 Zeolite 4A 32 50.39 32 48.85 Carbonate 14.5 22.83 14.5 22.14 Soap - - 2 3.05 63.5 65.5 Composition L initially gave a good product but lost its flow on drying. Inclusion of soap (Example 27) gave an excellent powder having a bulk density of 801 g/l and a dynamic flow rate of 139 ml/s. Examples 28 and 29 Examples L and 27 were repeated using zeolite MAP instead of zeolite 4A. Compositions 28 29 parts parts % % Surfactant 17 26.77 17 25.95 Zeolite MAP 32 50.39 32 48.85 Carbonate 14.5 22.83 14.5 22.14 Soap - - 2 3.05 63.5 65.5 Powder properties 28 29 Bulk density (g/l) 850 810 DFR (ml/s) 145 131 With this composition the incorporation of soap was not necessary in order to obtain good powder properties; on the contrary, no benefit was observed. Example 30 A composition similar to that of Example 24 but containing a different nonionic surfactant, NRE5, was prepared. All solid components had a particle size lower than 200 microns. The method of preparation was substantially as described in Example 11. The mean residence time of the granular detergent composition in the batch high-speed mixer/granulator was approximately 3 minutes. Composition % Surfactant: PAS 8.3 NRE5 19.5 Zeolite 4A 43.7 Carbonate 16.2 Water 12.3 100.00 The granular detergent composition obtained had a bulk density of about 770 g/l and a dynamic flow rate of 101 ml/s. Examples 31 and 32 Granular detergent compositions similar to that of Example 30 were prepared using a continuous high-speed mixer/granulator, the Lödige (Trade Mark) Recycler CB30. The liquid surfactant mix included fatty acid in combination with a stoichiometric amount of sodium hydroxide, which during the course of the mixing and densifying process formed soap. The rotational speed was 1600 rpm and the mean residence time of the granular mixture in the Recycler was approximately 10 seconds. The compositions of the granular materials leaving the Recycler were as follows. 31 32 Surfactant: PAS 8.5 8.3 NRE5 19.4 18.8 Zeolite 4A 52.6 47.1 Carbonate - 8.0 Soap 2.9 2.9 Water 16.4 14.9 100.0 100.0 Bulk densities were about 700 g/l, particle sizes 500-600 microns, and powder properties were good. Examples 33 to 35, Comparative Example M Fully formulated detergent powders were prepared to the formulations given below. M 33 34 35 Base powders LAS 7.85 - - - Coco PAS - 5.20 5.20 1.70 E7(s) 3.92 5.20 - - E3(s) 5.23 6.60 - - NRE7(s) - - 5.20 6.80 NRE3(s) - - 6.60 8.50 Soap 2.00 2.00 2.00 2.00 Zeolite 4A 32.00 32.00 32.00 - Zeolite MAP - - - 32.00 Carbonate 11.52 11.52 11.52 - Fluorescers 0.81 0.81 0.81 0.81 SCMC 0.60 0.60 0.60 0.60 Moisture 9.00 9.00 9.00 9.00 Postdosed Carbonate - - - 11.52 Silicate 0.45 0.45 0.45 0.45 Perborate mono 15.00 15.00 15.00 15.00 TAED 7.75 7.75 7.75 7.75 EDTMP 0.37 0.37 0.37 0.37 Enzymes 1.00 1.00 1.00 1.00 Antifoam 2.50 2.50 2.50 2.50 Perfume 0.60 0.60 0.60 0.60 100.00 100.00 100.00 100.00 Comparative Composition M is a high-performance concentrated powder based on a different surfactant system (LAS with nonionic surfactants) similar to that used in premium powders presently on sale in Europe. Surfactant systems (wt%) M 33 34 35 LAS 46 - - - Coco PAS - 30 30 10 E7(s) 23 30 - - E3(s) 31 40 - - NRE7(s) - - 30 40 NRE3(s) - - 40 50 100 100 100 100 The total amount of (non-soap) surfactant in each formulation was 17 wt%. All base powders were prepared in the Fukae FS100 batch high-speed mixer/granulator mentioned previously. Composition M was prepared as follows. Zeolite and carbonate (including an additional amount for neutralisation of LAS acid) were dosed into the Fukae mixer, followed by LAS acid, then a homogeneous surfactant blend (nonionic surfactant), fatty acid and an equivalent amount of sodium hydroxide solution). After granulation, the powder was dried using a fluidised bed, and the remaining ingredients postdosed. Compositions 33 and 34 were prepared as follows. Homogeneous surfactant blends were prepared by mixing PAS paste (70%), nonionic surfactant, fatty acid and an equivalent amount of sodium hydroxide solution. Zeolite and carbonate were dosed into the Fukae, followed by the surfactant blend. After granulation, the powders were dried using a fluidised bed, and the remaining ingredients postdosed. Composition 35 was prepared similarly except that no carbonate was present during granulation. Powder properties M 33 34 35 Bulk density 861 826 841 841 DFR 89 111 120 128 Detergency results Detergency was assessed in a Miele washing machine, in the presence of a soiled load, using a product concentration of 5 g/l, 26° (French) hard water, and a wash temperature of 30°C. The measure of detergency was the change in reflectance (460 nm) of a polyester test cloth soiled with kaolin and sebum (WFK 30D). Delta R 460 16.2 15.0 15.7 17.2 Examples 36 to 38 Further detergent powder formulations, containing zeolite MAP and coconut nonionic surfactants, are shown below. 36 37 38 Base powders Coco PAS 5.20 1.70 - E7 5.20 6.80 7.50 E3 6.60 8.50 9.50 Soap 2.00 2.00 2.00 Zeolite MAP 32.00 32.00 32.00 Fluorescers 0.81 0.81 0.81 SCMC 0.60 0.60 0.60 Moisture 9.00 9.00 9.00 Postdosed Carbonate 11.52 11.52 11.52 Silicate 0.45 0.45 0.45 Perborate mono 15.00 15.00 15.00 TAED 7.75 7.75 7.75 EDTMP 0.37 0.37 0.37 Enzymes 1.00 1.00 1.00 Antifoam 2.50 2.50 2.50 Perfume 0.60 0.60 0.60 100.00 100.00 100.00 Similar compositions may be formulated containing the narrow-range coconut nonionic surfactants NRE7 and NRE3, instead of the broad range materials E7 and E3, in the same proportions; or instead using one of the single materials NRE5, NRE4.6 or NRE4.2.

Claims: A particulate detergent composition having a bulk density of at least 650 g/l, characterised in that it comprises: (a) from 15 to 50 wt% of a surfactant system consisting essentially of: (i) 60 to 100 wt% of ethoxylated nonionic surfactant which is a primary C 8 -C 18 alcohol having an average degree of ethoxylation not exceeding 6.5 based on the total weight of the surfactant system, (ii) 0 to 40 wt% of primary C 8 -C 18 alkyl sulphate based on the total weight of the surfactant system; (b) from 20 to 60 wt% of zeolite; (c) optionally other detergent ingredients to 100 wt%; the composition being prepared by a wholly non-tower route by granulating the zeolite and surfactants in a high speed mixer/granulator. A particulate detergent composition as claimed in claim 1, characterised in that the surfactant system (a) comprises from 0.1 to 35 wt% of alkyl sulphate (ii). A particulate detergent composition as claimed in any preceding claim, characterised in that the surfactant system includes alkyl sulphate (ii) and the ethoxylated alcohol (i) has an average degree of ethoxylation of from 3 to 6.5. A particulate detergent composition as claimed in claim 1 or claim 2, characterised in that the surfactant system contains no alkyl sulphate (ii) and the ethoxylated alcohol (i) has an average degree of ethoxylation of from 4 to 6.5. A particulate detergent composition as claimed in any preceding claim, characterised in that the ethoxylated alcohol has an average degree of ethoxylation of from 4 to 5.5. A particulate detergent composition as claimed in any preceding claim, characterised in that at least 13 wt% of the ethoxylated alcohol is constituted by a single ethoxylation species. A particulate detergent composition as claimed in claim 6, characterised in that the single ethoxylation species contains 4 or 5 ethoxylation units per mole of alcohol. A particulate detergent composition as claimed in claim 6 or claim 7, characterised in that the ethoxylated nonionic surfactant consists of a single material having an average degree of ethoxylation within the range of from 4 to 5. A particulate detergent composition as claimed in any preceding claim, characterised in that it contains at least 17 wt% of the surfactant system. A particulate detergent composition as claimed in any preceding claim, characterised in that the zeolite is zeolite P having a silicon to aluminium ratio not exceeding 1.33. A particulate detergent composition as claimed in any preceding claim, characterised in that it comprises from 1 to 5 wt% of fatty acid soap. A process for the preparation of a particulate detergent composition as claimed in claim 1, characterised in that it comprises mixing and granulating the zeolite, ethoxylated alcohol, the primary alkyl sulphate (if present) in acid or salt form, and optionally other compatible ingredients, in a high-speed mixer/granulator. A process as claimed in claim 12, characterised by the steps of: (i) preparing the surfactant system in the form of a homogeneous liquid blend, and (ii) agglomerating the homogeneous liquid surfactant blend with the zeolite and other solids present in the high-speed mixer/granulator. A process as claimed in claim 12 or claim 13, characterised in that the homogeneous liquid surfactant blend also comprises a fatty acid and an alkali, or a fatty acid soap.

Inventors: AKKERMANS JOHANNES H M, CHAPPLE ANDREW PAUL, EMERY WILLIAM DEREK, EUSER HUIG, HULL MICHAEL, JOYEUX CHRISTOPHE, KNIGHT PETER CORY, SWINKELS PETRUS L J, AKKERMANS, JOHANNES H.M., CHAPPLE, ANDREW PAUL, EMERY, WILLIAM DEREK, EUSER, HUIG, HULL, MICHAEL, JOYEUX, CHRISTOPHE, KNIGHT, PETER CORY, SWINKELS, PETRUS L.J., AKKERMANS, JOHANNES H.M., UNILEVER RESEARCH, CHAPPLE, ANDREW PAUL, UNILEVER RESEARCH, EMERY, WILLIAM DEREK, UNILEVER RESEARCH, EUSER, HUIG, UNILEVER RESEARCH, HULL, MICHAEL, UNILEVER RESEARCH, JOYEUX, CHRISTOPHE, UNILEVER RESEARCH, KNIGHT, PETER CORY, UNILEVER RESEARCH, SWINKELS, PETRUS L.J., UNILEVER RESEARCH
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1992
Main classification: C11D17
IPC codes: C11D11, C11D17, C11D1, C11D3