WO2005037712A1

WO2005037712A1 - Method for the preparation of a suspension

Info

Publication number: WO2005037712A1
Application number: PCT/NL2004/000634
Authority: WO
Inventors: Theo Jan Osinga
Original assignee: Theo Jan Osinga
Priority date: 2003-10-20
Filing date: 2004-09-14
Publication date: 2005-04-28
Also published as: ZA200602827B

Abstract

The present invention relates to a method for the preparation of a suspension, in particular a sol, comprising amorphous small particles of a salt selected from the group consisting of a silicate based calcium salt, a silicate based magnesium salt, a silicate based strontium salt, a silicate based aluminium salt, a silicate based barium salt, a silicate based zinc salt, a silicate based zirconium salt, or a combination thereof, the method comprising the step of mixing an aqueous solution of a salt selected from the group consisting of a salt of calcium, magnesium, strontium, aluminium, barium, zinc and zirconium or a mixture thereof with a soluble alkali metal silicate salt and a soluble carbonate salt.

Description

Title: Method for the preparation of a suspension

The present invention relates to detergent compositions at least comprising a soluble carbonate salt in combination with a soluble alkali metal silicate. Detergent compositions known in the art apart from silicates and carbonates generally contain surface active agents, builders, (e.g.: zeolites, amorphous sodium alumino-silicates, crystalline alkali metal silicates, phosphates) , peroxide-type bleaching agents, and a series of additives, e.g.: co-builders, additives to minimise deposition of precipitates on the heating coils of the washing machine or on the fibres of the wash-goods and soluble silicates, also offering alkalinity, corrosion protection to metal parts and improving bleaching as well as having a builder function. Further additives that are generally used are bleach promoters (e.g.: TAED) , anti-re-deposition agents, preventing the re-deposition of soil, perfumes, fluorescing agents etc. Soluble alkali metal carbonates and alkali metal silicates' offer alkalinity in the wash and are potentially also suitable as builders or co-builders In practice detergent producers are confronted with the problem of deposition of various components on the wash-good as well as on the heating coils of the washing machine, during the washing operation. These deposits can have various sources, e.g.: • Re-deposition of soil. This can be due to insufficient dispersion of the soil. • Larger solid particles (above approx. 10 micrometers) , present in the detergent product that are not dissolved during the washing procedure, can_. be "trapped" between the fibres of the wash-good and consequently are not rinsed out. These larger particles can either be insoluble detergent components or be due to poor dispersion or poor solubility of components. • Due to reactions between components present in the wash, precipitates can be formed. When these precipitates are present as dispersed small particles they may not cause a problem, as very small particles can be rinsed out. However, precipitation can also take place on fibres of the wash-good or on parts of the washing machine (e.g.: on heating coils) . Residues on the wash-good is causing the so called "incrustation" and can be measured by the "ashing test". In this test the wash-good is burned after a series of repeated washes and the weight of the remaining ash is compared with the weight of the ash obtained after burning new fibres of the same wash-good. • Ca and Mg ions present in hard water, used for the washing process, are a major cause for precipitation during the wash. These ions can form precipitates with carbonate, silicates, phosphates and many organic acids, incl . : fatty acids, present in soaps or formed during the washing process as a result of hydrolysis of fatty soil. White deposits form an increasing problem due to a trend towards coloured fibres. • When precipitation takes place on the fibre surface, other components can be co-precipitated (trapped) , causing the so- called graying or yellowing of the wash-good. Silicate ions, and fatty acid ions cause precipitates of calcium silicates and calcium soaps and to a much lesser extent of magnesium silicates and magnesium soaps. Calcium silicate, magnesium silicate and the calcium soaps and magnesium soaps can form deposits on the fabrics and on the heating coils of the washing machine. Also carbonate ions react with calcium ions and magnesium ions potentially also forming precipitates on the fabrics and the heating coils, however this tendency is much less, as these carbonates tend to form crystalline particles, making them potential builders. However the formation of calcium carbonate is slow and retarded as a result of which there is sufficient time left for the calcium and magnesium ions to react with silicate or soap ions causing precipitation of calcium soaps, magnesium soaps, calcium silicates, magnesium silicates or other soils on fibres and heating coils having a detrimental effect on detergency. The detergent industry has actively been searching for solutions to minimise the formation of deposits on the surfaces of fibres or on the heating coils of the machine. The first solution was to use the well known builders which bind calcium and magnesium ions by keeping these ions in solution using complex forming agents (e.g.: sodium tri-phosphate, NTA, citrates etc.) or by binding the calcium and magnesium ions in small particles (zeolite 4A, zeolite X, zeolite MAP, amorphous alumino silicates or crystalline sodium silicate) . These builders were effective in binding Ca or Mg ions, but none of them completely solved the problem. Also sodium carbonate as potential builder has been extensively investigated, as carbonates are very cheap and would therefore be the preferred builder in case it would sufficiently fulfil all desired properties for a builder • Sodium-tri-phosphate slowly decomposes in aqueous media, forming phosphate ions, which form highly insoluble calcium phosphate precipitates. These precipitates even contribute to the deposit formation on fibres and machine parts. Furthermore it is not popular and banned in many countries as it is found to cause an environmental problem in surface waters. • NTA is banned in most countries for general use, due to environmental issues related to its use. • Citrate is not binding calcium strong enough, leaving a relatively high calcium concentration in solution, still allowing precipitation of insoluble calcium salts. • Zeolite 4A, zeolite X and the most efficient zeolite MAP bind calcium ions by exchange of sodium ions, present in the zeolites. Magnesium ions are bound less efficiently. The residual calcium ion concentration in solution is determined by the exchange equilibrium of the specific zeolite for sodium ions and calcium ions. Even when an excess of zeolite is present in the wash, the residual calcium concentration in solution will still be at a level comparable to the equilibrium calcium concentration for calcium-silicate. Therefore calcium- silicate formation can not be completely avoided. Zeolite MAP having by far the lowest equilibrium calcium concentration is superior in calcium binding. Zeolites are also relatively slow in binding calcium ions. This means, that precipitation of insoluble calcium salts (e.g.: calcium-silicate) can take place during the first minutes of the wash process, as long as the zeolite has not yet reached its equilibrium calcium concentration. • Crystalline sodium silicates were first introduced by the German firm Hoechst as another alternative to phosphate. These crystalline silicates were produced by heating precipitated amorphous sodium silicates with a molar ratio Si0₂/Na₂0 of above 1.5 at a temperature above 400^u C. The crystalline silicates, thus obtained, have a layered structure and function in the same way as zeolites, exchanging sodium present in the crystalline silicate by calcium and magnesium ions. With respect to binding of calcium and magnesium these crystalline silicates have the same limitation as zeolites, still allowing precipitation of calcium silicate during the first minutes of the wash process. These crystalline silicates have an extremely poor solubility and therefore are not falling under the heading soluble silicates.

• Several organic compounds can be further used as complex- forming agents for calcium ions, but are either too costly to be used as main builder or not sufficiently effective. Organic compounds also add to the oxygen demand when ending in the surface waters (BOD) while others are not completely biodegradable .

• Organic compounds are used as co-builder in combination with a main builder like STP or zeolite (4A, X or MAP) . Well-known co- builders are polysaccharides and co-polymers of acrylic acid and maleic acid.

• Soluble silicates (e.g. sodium silicates) bind calcium and magnesium ions and are used as builders. However as these builders function by forming insoluble calcium and magnesium silicates, which do not only form dispersed small particles, but can also precipitate on the various surfaces (e.g.: heating coils and textile fibres) , these silicate builders are inferior to zeolites and tri-phosphate .

• Soluble carbonate salts (e.g.: sodium carbonates, incl . sodium bicarbonate and sodium sesquicarbonate) seem to be the most suitable soluble salts to be used as detergent builders, as they are extremely low priced and do not tend to precipitate on fibre surfaces, but mainly forming very finely dispersed precipitates of (crystalline) calcium- and magnesium carbonates. Carbonates were intensively studied around 1970 as alternative "Builder", when an alternative for phosphate had to be found. A major problem related to the use of carbonate being however, that the reaction between carbonate ions and the free metal ions (Ca and Mg) is relatively slow, even having an initiation phase. This initial delay being caused by a retarded nucleation of the calcium carbonate ana τ.ne magnesium carbonate.

As a result of the delayed reaction between carbonate ions and calcium and magnesium ions, Ca and Mg ions react with organic components present in the wash, e.g.: surfactants and soil as well as with silicate ions when present. These reactions with surfactants lead to a reduced surfactant action i.e.: worse detergency and the reaction with the soil can lead to worse removal of soil. Furthermore the precipitates of calcium soaps, magnesium soaps, calcium silicates and magnesium silicates tend to adhere to the fibres and the heating coils. It was reported in US 1 460 646, US 3 997 692 and NL 7305925 that addition of crystallisation seeds increased the speed of the reaction between the anion of the soluble salt (i.e.: carbonate) and the free Ca and Mg ions, thus reducing the time available for the Ca and Mg ions to react with the organic compounds, the soil and silicate ions. Although in these patents many seeds were suggested for the formation of calcium carbonate or magnesium the only seeds tested and found to be successful were calcium carbonate or its precursors calcium oxide and calcium hydroxide. In fact aluminium-, calcium- and magnesium silicates were also listed as potential seeds, although these silicates were already used as flow promoters and clearly did not fulfil the required seeding effect for the precipitation of calcium- or magnesium carbonate, as CaC03 seeds had to be additionally added.

These patents also claim that magnesium carbonate and its precursors magnesium hydroxide and magnesium oxide were suitable seeds for the formation of calcium carbonate and magnesium carbonate without providing tests to back up these claims. It can be assumed that these magnesium compounds are indeed also effective, when used as seeds

Although the known "Seeded Builder System" based on alkali metal carbonates in combination with calcium carbonate or magnesium carbonate seemed to offer a good and cheap builder its success was rather poor due to the following reasons: It was difficult to create calcium carbonate with large surface areas. A large surface area is required as the surface of the calcium carbonate is easily poisoned by adsorption of fatty acids, dyes and other poisons present in the soils or in the detergent formulation, inactivating the surface of the seeds for the precipitation of calcium carbonate and magnesium carbonate. Therefore large and unacceptable high amounts of seeds are required. The carbonate particles first assessed were in the micron area and not porous, therefore the outside surface area was relatively small. To create larger surface areas extensive work was carried out to develop porous calcium carbonates, which was to some extent successful. However, although being more effective than non-porous calcium carbonates, even the best porous calcium carbonates that could be developed were still not sufficiently active seeds for the formation of calcium carbonate and magnesium carbonate. Large quantities of these specially developed calcium carbonate seeds were still required to sufficiently solve the problems (e.g.: up to around 10 percent by weight of the total detergent formulation was needed) . Furthermore these specially developed calcium carbonate seeds were very expensive, leaving no economic benefits any more for this old seeded carbonate builder system. A possible additional reason for the restricted effectiveness of the calcium carbonate seeds was that due to the larger particle size of the seeds, larger amounts were probably also required to reduce the distance between seeds in the wash liquor sufficiently to minimise the free space for calcium and magnesium ions to react with other ions, like soap ions, dyes or silicate ions. Another possible reason for the need for larger amounts of calcium carbonate seeds, which was not reported either could be, that seed particles grow by the precipitation of the calcium carbonate formed in the wash on the seeds. Starting with larger micron size particles can lead to particles, with particle sizes above 10 micrometer, becoming unacceptable in the wash. • As mentioned in WO 02/086042, calcium carbonate seeds are specific for carbonates and do not enhance the speed of calcium silicate formation or magnesium silicate formation in case soluble silicates are incorporated in the detergent formulation. In fact calcium silicate formation or magnesium silicate formation obtained from the reaction of silicate ions with calcium and to a lesser extent with magnesium ions is already very fast and without an initiation phase in the absence of seeds. • As the problems connected to the use of carbonate, being too slow as main "builder" could not be solved to complete satisfaction, carbonate was only applied in cheap, lower grade formulations or in areas where water of very low hardness was available, e.g. in Indonesia. There have been several further attempts to reduce precipitation on the various surfaces e.g.: on fabric-fibres. Additives were advised that increase the soil carrying properties of the liquor and reduce the tendency of the surfaces of the fibres to act as nucleus for precipitation. It was found, that different additives were needed for different types of surface.

The following German Patents describe a series of additives that can be applied: 2054097; 2165835; 2165898; 2165900; 2165804; 2165803; 2165834. The additives advised were mainly polymers with anionic groups, e.g.: cellulose and derivatives thereof as well as poly- acrylates, poly-metacrylates, poly-maleates and their co-polymers. It was reported in these patents, that cellulose type additives (preferably CMC) were effective for cotton, but practically ineffective for synthetic fibres, while several synthetic polymers (preferably PVP) are effective for synthetic fibres. Although these additives reduce deposit formation, some deposit is still formed. More recently a series of new attempts have been made to optimise the performance of sodium-carbonate and soluble sodium- silicate as main builder or at least as co-builder in combination with STP or with zeolite. (GP: 4406592A1; 4415362A1; 4442977A1; 4400024A1; 19509303A1; 19601840A1; 19611012A1; 19710383A1; 19709411A1; 19843773A1 and USP 6,013,617). In these patents it is either proposed to control (reduce) the dissolution rate of the silicate or to form specific polymeric silicate species, that are claimed to be more efficient in binding calcium and magnesium. These patents clearly show that, although some reduction in deposition of residues was demonstrated, residue formation still takes place. In a most recent invention, i.e.: WO 02/086042 (PCT/EPO2/04419) , a new solution to the incrustation problems connected to the use of silicates as builder system was reported. To that end that invention is characterised in that the detergent composition further comprises very small particles of amorphous calcium silicate or amorphous magnesium silicate. The smallest particles reported in this patent were far below one micron. Even sols of amorphous calcium silicate particles and amorphous magnesium silicate particles were produced in a soluble alkali metal silicate solution. These particles are so efficient, that a concentration of around 1 percent by weight related to the soluble silicate gave already sufficient protection against precipitation of the calcium silicate on fibres or heating coils. However there is still another problem connected to the use of silicate as main builder caused by the high alkalinity of soluble alkali metal silicates. For safety reasons the detergent industry is forced to either limit the quantities of alkaline alkali metal silicate used in household detergents or limit the molar ratio

Si0₂/M₂0 of the alkali metal silicate, in which M stands for alkali metal, to higher values. However, increasing the molar ratio Si0₂/M₂0 has a negative effect on solubility. As these safety rules also apply to the soluble silicates in the suspensions or sols of WO 02/086042, the use of the suspensions or sols claimed in this patent application is also limited. Therefore, there is a strong need for solving the nucleation problems connected to the use of alkali metal carbonate as builder as it would offer a soluble and economically most attractive builder, which can be more widely applied at higher concentrations for the following reasons: • Alkali metal carbonate is much cheaper than alkali metal silicate . • Alkali metal carbonate is also less alkaline than alkali metal silicate and therefore the quantity that may be used in detergents is not limited by the safety rules. • Therefore much more carbonate could be used as builder. • Alkali metal carbonate has an excellent solubility, superior to alkali metal silicates and does not tend to cause caking of powders like soluble silicates . • Shift in the market towards more concentrated detergent products and tablets. • Shift in the market towards coloured fabrics. • The builders zeolites and crystalline sodium silicate are insoluble and can negatively influence dispersion and dissolution of denser detergent products, e.g.: concentrates and tablets, possibly causing white residues on fabrics. The industry can handle this problem at a cost • Traces of white residues are more disturbing on coloured fabrics . The object of the present invention is to provide a solution to at least one of the problems related to the use of soluble carbonates as builder or as co-builder, which is far superior to the known "Seeded Carbonate Builder System". It is a further object of the present invention to provide an alternative compound ("intermediate product") for use in detergents. To this end the present invention provides in a first aspect a method for the preparation of a suspension, in particular a sol, comprising amorphous small particles of a salt selected from the group consisting of a silicate based calcium salt, a silicate based magnesium salt, a silicate based strontium salt, a silicate based aluminium salt, a silicate based barium salt, a silicate based zinc salt, a silicate based zirconium salt or a combination thereof, the method comprising the step of: mixing an aqueous solution of a salt selected from the group consisting of a salt of calcium, magnesium, strontium, aluminium, barium, zinc and zirconium or a mixture thereof with a soluble alkali metal silicate salt and a soluble carbonate salt. In a further aspect the present invention provides an intermediate product obtainable by the method according to the present invention. In an even further aspect the present invention relates to the use of the intermediate product for the preparation of a detergent composition. Furthermore the present invention relates to a detergent composition comprising the intermediate product. The detergent composition may comprise a detergent product for fabric washing, (e.g. mechanical) dish washing and industrial cleaning products in any suitable form such as a liquid, powder, tablet, gel, etc. The present invention therefore also relates to the use of the detergent composition for fabric washing, (mechanical) dish washing, and cleaning in general. It has now been found, that fast mixing of a combination of a relatively concentrated calcium salt solution or a magnesium salt solution or mixtures thereof with a relatively concentrated mixture of a soluble alkali metal silicate and a soluble carbonate solution under intensive stirring, preferably at elevated temperatures can give very small insoluble calcium and/or magnesium salt particles and that even sols of these calcium salt particles or magnesium salt particles or mixtures thereof can be produced in the alkali metal silicate and carbonate solution. We were not able to define, whether these small sol particles were only pure amorphous calcium silicate or amorphous magnesium silicate particles or mixtures thereof or whether also calcium carbonate or magnesium carbonate was formed and present in the particles or alternatively on the surface of the particles or present as separate particles. XRD analysis did not show any crystalline calcium carbonate or magnesium carbonate. This means, that in case calcium carbonates or magnesium carbonates are co-precipitated with the calcium silicate or the magnesium silicate the calcium carbonates or magnesium carbonates are either present in amorphous form or more likely that the particle size is so small (nanometer size or smaller) that they could not be detected by XRD. The calcium silicate or magnesium silicate formed is amorphous. The composition of the small particles present in the suspensions or sols could not be defined either, as we were also not able to separate the small sol particles from the solution of silicate and carbonate in which they were produced. Therefore the small particles according to the invention will further be called "silicate based insoluble calcium salts or silicate based insoluble magnesium salts in soluble mixed alkali metal silicate and soluble carbonate". It should be understood, that these silicate based salts are produced and present in a mixed solution of soluble alkali metal silicate and soluble carbonate and most probably comprise some calcium carbonate or magnesium carbonate or mixtures thereof and that the calcium or magnesium silicate is amorphous. It should also be understood, that in stead of soluble calcium salts or soluble magnesium salts, also other soluble metal salts can be used to react with the soluble alkali metal silicate and the soluble carbonate forming suspensions but also sols of very small particles of silicate based salts. Examples of such soluble metal salts are soluble salts of strontium, barium, aluminium, zinc, zirconium etc. These salts can be used also in combinations, preferably with calcium or magnesium. As the preferred metal ions are calcium and magnesium these ions are further used in the text, although the other ions mentioned above are also meant. The original objective of the addition of soluble carbonate to the soluble alkali metal silicate to the suspensions according to WO 02/086042 was to reduce the alkalinity of the suspensions and the sols by reducing the silicate content, the surprise came when the product obtained was tested on performance in washing. In order to assess the functioning of the new products in an alkali metal carbonate rich environment in more detail a test series was carried out in a more basic model system developed for this purpose as reported in the Examples. In this test, starting with pure hard water, following components were added to the hard water: sodium carbonate (Ex. A), sodium carbonate and sodium silicate (Ex. D) , sodium carbonate and a (dried) sol of small particles of amorphous calcium silicate in a sodium silicate solution (Ex. G) and sodium carbonate and a (dried) sol of silicate based insoluble calcium salts in a mixed solution of sodium silicate and sodium carbonate (Ex. J) . The sample used in Example J being according to this invention. In Examples A, D and G there was an initial delay in the calcium uptake (clearly demonstrating the known initiation phase of calcium carbonate formation) of around 70 to 100 seconds. This demonstrates that the presence of silicate or of a sol of calcium silicate in a sodium silicate solution has no significant influence on the crystallisation of calcium carbonate in a system free of seed poisons. Surprisingly, in Example J, using a sol according to the invention, this delay was seriously reduced to around 40 seconds. Addition of large quantities of calcium carbonate seeds as shown in Examples B, E, H and K could maximally reduce the delay to around 20 to 30 seconds. The surprising result of Example J shows, that this new sol according to the invention, promotes the crystallisation of calcium carbonate in an extremely efficient manner, as the quantity of the small particles of silicate based calcium salt within this sol, probably carrying some calcium carbonate is only around 1 % of the amount of calcium carbonate seeds used in the other experiments. A quantity of around 100 mg. pure calcium carbonate seeds is needed to match the seeding effectiveness of Ex. J, i.e. to reduce the delay from 70 to 100 seconds to 40 seconds as found in Example J. The best explanation for this strong "seeding" by the sol particles according to the invention is to assume that these sol particles contain extremely small (e.g.: nanometer-size or smaller) calcium carbonate particles in combination with the amorphous calcium silicate. The amount of calcium carbonate can only be a fraction of the total weight of the sol particles. Therefore these calcium carbonate particles, when indeed present and acting as seeds, must be extremely active and efficient. The high efficiency could be explained by the extremely small size of the assumed calcium carbonate particles being more active per unit surface area and offering an extremely large surface area, that will not be matched otherwise. The extreme small size of the sol particles results in an extremely large number of particles dispersed in the liquor, thus minimising the free space between these particles for calcium ions to react with other components. Furthermore the large surface area of the amorphous calcium silicate particles protects the calcium carbonate seed surface from being poisoned. Probably the high efficiency of the sol particles according to the invention containing calcium silicate and most probably also calcium carbonate results from a combination of these possible causes. The particles in the suspensions or sols according to the invention, i.e.: silicate based calcium salts or silicate based magnesium salts or mixtures thereof in a mixed solution of a soluble alkali metal silicate and a soluble carbonate are therefore technically and economically more effective as seeds for carbonate based builder systems than the calcium carbonate seeds known already, allowing much lower seed concentrations in the wash and much higher carbonate concentrations . A concentration in the products according to the invention of around 2 percent by weight of the particles of silicate based calcium salt or magnesium salt seeds relative to the combined weight of alkali metal carbonate and soluble alkali metal silicate is already effective. A further benefit of these new small particle seeds of the silicate based insoluble calcium salts or magnesium salts is that they are easy to produce and also economically attractive, allowing alkali metal carbonate to be the main builder as also shown in Example J. There is ample space for product optimisation to further increase the seeding activity and economic efficiency of the suspensions or preferably the sols according to this invention e.g.: by increasing the content of small insoluble silicate based particles by addition of more soluble calcium-, magnesium- or alternatively strontium-, barium, zirconium, zinc or aluminium- salts or mixtures thereof to the solution of alkali metal silicate and soluble carbonate or by increasing the ratio between soluble carbonate and alkali metal silicate. Suspensions and preferably the sols according to the invention combine a few important properties and are true "Multi Functional Components" for detergent products: They combine the superior functions of this invention with those of the previous patent application WO 02/086042 (PCT/EPO2/04419) , i.e.: • A unique novel highly efficient "seeding activity" for the reaction between carbonate ions (used as detergent builder or co-builder) with hard water ions (Ca and Mg) . • Allowing higher carbonate (builder) contents in detergent products . • Minimising precipitation of calcium silicate and magnesium silicate on fabrics (incrustation) and heating coils based on the presence of the extremely small calcium silicate and/or magnesium silicate particles as already claimed in WO 02/086042 (PCT/EPO2/04419) . • Minimising precipitation of calcium silicate and magnesium silicate on surfaces of wash goods in (mechanical) dish washing. This is particularly important when washing (crystal) glass ware, as deposits of calcium silicate and magnesium silicate cause the clear (crystal) glasses to turn opaque. • Better "detergency" as calcium- and magnesium- hard water ions are bound much faster by carbonate leaving much less time for calcium- and magnesium- ions to react with other components like soap and soil. • Less re-deposition of soil and consequently less graying as no or less soil can be trapped as no or less precipitation of calcium silicate or magnesium silicate takes place • A conclusion, that is also drawn from the Examples of this patent application is that the small particles of the suspensions and preferably of the sols according to this invention adsorb compounds that poison calcium or magnesium carbonate seeds. It can be expected, that the small particles according to WO 02/086042 (PCT/EPO2/04419) show the same protection against seed poisoning .

• Protection against seed poisoning improves the seeding efficiency under practical wash conditions further by reducing the negative effects of seed poisons, which are always present under practical wash conditions. This seed poison protection applies to the seed function of the particles according to this invention but also to seeds of calcium carbonate added separately or additionally to the wash. • Products according to this invention deliver seeds already. Therefore no additional seeds are needed. However, optimisation programs may lead to the conclusion that for specific wash tasks an optimal result may be obtained with respect to maximum detergency, total alkalinity and/or economics by combining the product according to this invention with additionally added calcium carbonate seeds.

• Improved stability of per-oxy bleach systems (incl. per-borate, per-carbonate and systems containing bleach activators like TAED and SNOBS) , resulting from the co-precipitation (or entrapment) of titanium and iron present in soluble silicates during the reaction of calcium or magnesium ions with silicate ions and/or carbonate ions during the preparation of the suspensions or preferably sols according to this invention. A further improvement being realised by the adsorption of other heavy metal ions e.g.: copper- zinc-, tin- and manganese ions present in the wash by the small silicate based calcium salts and preferably by the silicate based magnesium salts.

• Controlled alkalinity by optimising the ratio between the silicate and the carbonate used. • Corrosion protection for metal parts due to the presence of soluble silicate.

• The suspensions or preferably the sols according to the invention can be dried to form powders or granules, which can be re-dissolved in water. The suspensions thus obtained again having the same positive properties as the original suspensions or sols . • These powders can be compressed or granulated to obtain denser products as required in more concentrated detergent products, having still the same positive properties. The dispersions or sols according to this invention can be dried and granulated according to various techniques known in the art forming powders or granules. Drying techniques comprise spray drying and Turbo drying as offered by the firm V.O.M.M. in Milan, Italy. Granulation techniques comprise Turbo drying, granulation and compaction. The presence of soluble alkali metal silicate in the carbonate solution is highly preferred for preparing the very small silicate based insoluble calcium salt particles or silicate based insoluble magnesium salt particles. Mixing a soluble calcium salt with only a soluble carbonate e.g. an alkali metal carbonate solution always gives large crystalline particles. The presence of 5 percent by weight soluble alkali metal silicate in a concentrated carbonate solution does not result in small particles of the calcium or magnesium salt either. At least 50 % by (dry) weight of soluble alkali metal silicate relative to the total (dry) weight of soluble alkali metal silicate and soluble carbonate is preferably present during the preparation of the suspensions or preferably the sols according to this invention. More carbonate can be added afterwards, e.g. before drying. An alternative, but less preferred method for preparing suspensions or preferably sols of small silicate based insoluble calcium salt particles or silicate based insoluble magnesium salt particles or mixtures thereof in the presence of solutions of mixtures of alkali metal silicate and soluble carbonate is as follows. At first produce a suspension of insoluble amorphous calcium silicate or amorphous insoluble magnesium silicate or mixtures thereof in an alkali metal silicate solution according to WO 02/086042 and add to the suspension or sol thus formed under severe stirring and preferably at higher temperatures (e.g. 50° C to 95° C) soluble carbonate, preferably in combination with additional soluble calcium salt and/or magnesium salt, or preferably solutions thereof) . It is possible to further reduce the amount of soluble silicate and increase the amount of carbonate in the wash in order to reduce the alkalinity of the wash liquor as well as improve the economics when applying the seeds containing products according to this invention, by first producing a silicate rich "base" suspension or preferably a silicate rich "base" sol of silicate based insoluble calcium salt or silicate based insoluble magnesium salt or mixtures thereof in a mixed solution of alkali metal silicate and soluble carbonate and by later adding additional alkali metal carbonate. The later addition of additional alkali metal carbonate can either be in the form of an aqueous solution or even in the form of a powder or a granule to the "base" suspension or "base" sol, or alternatively when producing the final detergent product to crutcher mixers (before spray-drying) or as separate powders or granules of sodium carbonate or sodium bicarbonate to the final detergent product by dry-mixing. The detergent compositions according to the invention are not limited to detergents in granular form or powder form, but also encompass liquid detergent compositions, detergent gels, detergent tablets and the like. Advantageously the compositions of the suspensions, according to the invention, comprise up to 25 % by weight and preferably up to 10 % by weight or more preferable up to 5 percent by weight and most preferably up to 3 % by weight of a small particle size silicate based calcium salt or a silicate based magnesium salt or mixtures thereof. This silicate based calcium salt or magnesium salt or mixtures thereof being prepared by mixing under intensive stirring a solution of a soluble calcium salt or a soluble magnesium salt or mixtures thereof with a relatively concentrated solution comprising alkali metal silicate and soluble carbonate preferably at elevated temperatures. More preferably the composition is a sol comprising 0.1 to 10 % by weight, preferably 0.1 to 5 % by weight and more preferably 0.5 to 3.0 % by weight of the small particle size silicate based calcium salt or silicate based magnesium salt or mixtures thereof. Dried products according to the invention contain preferably maximally 35 percent by weight water and preferably max. 23 percent by weight water and most preferably 15 to 21 percent by weight water and 0.1 to 40 % by weight, more preferably 0.2 to 25 %, more preferably 0.2 to 10 percent by weight and more preferably 1.0 to 6.0 percent by weight of the small particle size silicate based calcium salt or silicate based magnesium salt or mixtures thereof. The particle size of the synthetically produced small particles of silicate based calcium salt or silicate based magnesium salt or mixtures thereof according to this invention, present in detergent compositions according to the invention, is more than 99 percent by weight below 10 micrometers, preferably more than 90 percent by weight below 2 micrometers, more preferably 85 percent by weight below 1 micrometer, more preferably 85 percent by weight below 0.5 micrometer and more preferably 85 percent by weight below 0.2 micrometer and more preferably 80 percent by weight below 0.1 micrometer and most preferably 70 percent by weight below 0.05 micrometer. Preferably the particles being formed in a relatively concentrated aqueous solution of a mixture of soluble carbonate and alkali metal silicate by quickly adding a relatively concentrated solution of a calcium salt or a magnesium salt or mixtures thereof, preferably at an elevated temperature.

The alkali metal silicate solutions used for this invention preferably have a Molar Ratio Si0₂/M₂0 between 1.0 and 4.0, preferably between 1.5 and 3.3 and more preferably between 1.8 and 2.8. The soluble carbonate salts used for this invention preferably have a Molar Ratio C0₂/M₂0 between 0.5 and 3, preferably between 0.8 and 2.1. The most preferred form of the products according to the invention is a stable sol, which is not settling during storage and with more than 95 % by weight of the silicate based calcium salt or silicate based magnesium salt particles having a particle size below 2.0 micrometer, preferably more than 90 having a particle size below 1 micrometer, more preferably 85 % of the particles having a particle size below 0.2 micrometers and more preferably 80 % of the particles having a particle size below 0.05 micrometers and most preferably 80 % of the particles having a particle size below 0.01 micrometer. In case a few percent of larger size particles is present, these can optionally be separated by settling, centrifuging etc. if required. Soluble carbonates or soluble alkali metal silicates used for this invention, comprise sodium-, potassium-, lithium- and ammonium- carbonates and sodium-, potassium- or lithium- silicates, including bicarbonates and sesquicarbonates . For detergent applications sodium carbonates and sodium silicates are preferred for economic reasons, while potassium carbonates and potassium silicates can be used in some special applications. The mixtures of soluble carbonates and alkali metal silicates according to this invention, containing small particles of silicate based calcium salt seeds or silicate based magnesium salt seeds or mixtures thereof can be supplied to detergent producers either as liquors (aqueous suspensions or sols) , as dried powders or as granules . The weight ratio between the soluble alkali metal silicate and the soluble carbonate in the mixture used for preparing the silicate based calcium salt or silicate based magnesium salt according to this invention is preferably between 1 to 10 and 99.9 to 1, preferably between 1 to 3 and 99 to 1 and more preferably between 1 to 2 and 99 to 1 and even more preferably between 1 to 1 and 99 to 1 and most preferably between 70 to 30 and 95 to 5. In order to increase the level of carbonate for economical reasons or to reduce the alkalinity in detergent products or in the wash, it is possible to add more carbonate to the "base" product according to the invention later, either to the suspension or to the sol before drying or alternatively in dry form to the dried products according to the invention or during the detergent production process . Other components can be added before drying the soluble mixed carbonate/silicate suspensions or sols ("the intermediate product") according to this invention, comprising citrate salts, polymers or co-polymers of acrylic acid and maleic acid, PVP, additional sodium carbonate, sodium sulphate, surface active agents, textile softeners etc. The dried powders thus formed generally called "Compounds" ("the intermediate product" or "the dried intermediate product") and in this case being based on the mixtures of soluble carbonate and alkali metal silicate containing the small particles of silicate based calcium salt or magnesium salt or mixtures thereof according to the invention, can also be granulated or compacted to form "Compound" granules. Drying can preferably take place in a spray-tower or in a "turbo-dryer" as offered by the Italian firm VOMM (Milan) . A special feature of these dried suspensions or sols is that when these powders are dissolved, the suspensions or sols are formed again as was the case for the silicate suspensions and sols reported in WO 02/086042 (PCT/EPO2/04419) . Intermediate products according to the invention can be introduced into detergent products in various manners. They can be supplied to the detergent industry either as suspension or preferably as a stable sol or as a dried powder or as granules. The dried powders and granules may comprise other detergent components and then be introduced as Compounds (or "intermediate products") . Intermediate products according to the invention, i.e.: synthetically produced suspensions or sols of the silicate based calcium salt and silicate based magnesium salt or mixtures thereof in mixed aqueous solutions of carbonate and alkali metal silicate can be incorporated in a spray-dried detergent similarly as carbonates and silicates are being introduced in various manners, e.g.: by addition as suspensions, preferably as sols, as fine powders or as granules to the detergent slurry before spray-drying, e.g. in the "crutcher". Synthetically produced suspensions or sols of a silicate based calcium salt or a silicate based magnesium salt or mixtures thereof in alkali metal silicates and soluble carbonates can also be post dosed in the form of powders or granules to the spray dried detergent "base" powder. Other components may be present in these powders in which case the "compounds" can be post-dosed as well. In case detergent powders are produced in a dry-mix process, silicate based calcium salt or silicate based magnesium salt or mixtures thereof in a solution of soluble alkali metal silicate and soluble carbonate can be dosed to the detergent mix in powder form or in granular form or as "compounds", containing preferably also one or more of the other components of the detergent formulation. Detergent powders can be further processed according to various techniques known in the art, thus forming "compacts" extrudates, tablets etc. In order to maximise economics it is preferred to maximise the ratio between soluble alkali metal silicate and soluble carbonate in the products according to this invention and to add the remaining part of the soluble carbonate which is needed for the detergent formulation later, either before drying of the product according to the invention or when producing the detergent product. This procedure also provides more flexibility with respect to the formulations of various detergent products with varying ratios between silicate and carbonate. The ratio between calcium, magnesium or a mixture thereof and soluble silicate should preferably be such, that less than 50 % of the silicate can be precipitated by the calcium or magnesium ions. More preferably the ratio is such, that less than 25% of the silicate can be transferred into calcium silicate or magnesium silicate or mixtures thereof and more preferably the ratio is such, that less than 10 % of the silicate can be transferred into calcium silicate or magnesium silicate or mixtures thereof and most preferably the ratio is such, that less than 5 % of the silicate can be transferred into calcium silicate or magnesium silicate or mixtures thereof. The present invention further provides a process for the preparation of powders or granules of a mixture of alkali metal silicates and alkali metal carbonates comprising the step of drying the dispersions, suspensions or preferably sols to a suitable water content. The suspensions or sols containing before drying a suitable amount of small particle size insoluble silicate based salts selected, from the group of calcium, magnesium, strontium, zirconium, aluminium, barium, zinc or mixtures thereof. In the above mentioned method apart from the silicate based calcium and silicate based magnesium salts, also other compounds may be added before drying, e.g. additional soluble alkali metal carbonate, surfactants etc. Advantageously the granules are milled to a powder having a particle size of below 2000 micrometer, preferably 90 percent by weight of the powder having a particle size of below 800 micrometer and most preferably 90 percent by weight of the powder having a particle size of below 600 micrometer. Preferably the powder formed is granulated or compacted (e.g.: in a roller compacter) to form larger and more dense particles. More preferably the granules obtained are milled and sieved to suitable particle sizes, preferably between 25 and 1200 micrometer, more preferably 90 percent by weight of the granules having a particle size of between 25 and 800 micrometer and most preferably 90 percent by weight of the granules having a particle size of between 50 and 600 micrometer. Further the invention provides suspensions, sols, powders or granules of a mixture of silicates and carbonates obtainable by the methods according to the invention. Finally the invention provides the use of suspensions, sols, powders or granules of mixtures of silicates and carbonates according to the invention for the preparation of detergent compositions. The detergent compositions are preferably used for fabric washing, (mechanical) dish washing, and industrial cleaning. It is furthermore possible to add one or more other components to the suspension or sol of synthetically produced silicate based calcium salt or silicate based magnesium salt or mixtures thereof in mixtures of soluble alkali metal silicate and soluble carbonate before drying (e.g.; citrate, polymers or co-polymers of acrylate and maleate, PVP, sodium carbonate, sodium sulphate, surface active agents, textile softeners etc.) forming the so-called "compounds". These compounds in powder form can also be granulated or compacted producing the "compounds" in powder or granular form. Preferably the powders or granules of "compounds" thus obtained are milled and sieved to suitable particle sizes, preferably between 25 and 1200 micrometer, more preferably 90 percent by weight of the granules having a particle size of between 25 and 800 micrometer and most preferably 90 percent by weight of the powders or granules having a. particle size of between 50 and 600 micrometer. It is preferred to apply the products according to this invention in combination with other systems advised to reduce the formation of residues, and to reduce the problem of incrustation, graying and yellowing related to deposits on fabric surfaces. In a specially preferred system synthetically produced silicate based calcium salt seeds or silicate based magnesium salt seeds or mixtures thereof in combination with soluble alkali metal silicate and soluble carbonate are used in combination with one or more other builders (STP, crystalline sodium silicate, zeolite 4A, X or preferably MAP and amorphous sodium alumino silicates) , additional soluble alkali metal carbonate and optionally also a co-builder (e.g.: co-polymers of acrylic and maleic acid or polysaccharide) orr even some additional quantity of the known crystallisation seed (porous) calcium carbonate. It is possible to also use additives like CMC, derivatives of CMC and PVP to reduce the tendency of fibre surfaces to act as nucleus for precipitation. For economic reasons sodium carbonates and sodium silicates arre generally most preferred. Potassium silicates and potassium carbonates are being used in liquid detergent products or in combination with sodium carbonate or sodium silicate to improve solubility (e.g. max. 10 wt. % of potassium carbonate or potassium carbonate) . Detergent products comprising soluble alkali metal silicates and soluble alkali metal carbonates and synthetically produced silicate based calcium salt or silicate based magnesium salt or mixtures thereof according to this invention, can furthermore comprise all known detergent components in suitable amounts, e.g.: • Zeolite builders, e.g. : zeolite 4A, zeolite X, preferably zeolite MAP • Other builders, e.g.: crystalline sodium silicates with a layered structure, sodium tri-phosphate (STP) , sodium citrate, amorphous alumino silicates or additional alkali metal carbonate and alkali metal silicates containing small particle size amorphous calcium silicate and/or magnesium, silicate according to WO 02/086042 (PCT/EPO2/04419) . • Co-builders, e.g.: polysaccharides, co-polymers of acrylic acid and maleic acid • Surface active agents e.g.: of the anionic type, the nonionic type or the cationic type. • Bleaching agents, e.g.: per-borate, per-carbonate • Bleach activators, e.g.: TAED or SNOBS. • Anti re-deposition agents, e.g. derivatives of cellulose (e.g.: CMC) , PVP and other synthetic polymers • Fluorescing agents * Perfumes * Fabric-softeners * Calcium carbonates * Dispersants etc.... • Anti-caking agents or powder flow promoting agents, e.g. inert silicates, and carbonates, generally being crystalline and of natural sources, silica (e.g. milled quartz powder, zeolites, alumino-silicate etc.

EXAMPLES Materials used: • Hard water (40° FH = French Hardness) , of which the pH was raised to 10.0 by means of a pure 5 % ammonia solution. • A commercially available aqueous sodium silicate solution from the firm Ineos Silicas B.V., Eijsden, the Netherlands, (Crystal 00012) with a Molar Ratio Siθ₂/Na₂0 of 2.0 and a dry solids content of 45.7 % by weight. (Si0₂ content 30.3 % and Na₂0 content 15.4 % by weight) . • A concentrated aqueous solution of 2.2 N (pure) calcium chloride, containing 20.7 % CaCl₂ .2aq. (ex Merck, Germany) by weight) . • A concentrated aqueous solution of 2.2 N. (pure) magnesium chloride, containing 18.21 % MgCl₂.2aq. (ex Merck, Germany) by weight). • A concentrated aqueous solution of aluminium sulphate obtained by dissolving 510.1 g aluminium sulphate.18 aq. in 643 g de- mineralised water. This solution of 1153 g, having a volume of 900 ml, has a concentration of 44.2 % by weight of Al₂ (S0₄) ₃.18aq. and a strength of 1.7 Molar (on the basis of Al) . The aluminium sulphate used being a technical grade ex. Rumania. • Anhydrous sodium carbonate powder (pro analysis, ex Merck, Germany) . • Calcium carbonate powder (precipitated, pro-analysis, ex. Merck, Germany) . • Commercially available spray-dried soluble sodium silicate powder ex. Ineos Silicas B.V. Eijsden, the Netherlands. Dry Solid content: 80 %, Molar Ratio: Si0₂/Na₂0: 2.0. • A solution of 5.0 g per litre of sodium stearate in 1 litre of a warm 0.01 molar sodium hydroxide solution.

Preparation of sols of very small amorphous particles of insoluble metal silicates in aqueous solutions of a soluble alkali metal silicate and spray-dried powders thereof used in the Examples ■ Sol 1 Sol of amorphous calcium silicate in a sodium silicate solution.

Procedure: Heating 64.6 parts by weight of a sodium silicate solution with a molar ratio Si0₂/Na₂0 of 2.0 and a sodium silicate content of 45.7 % by weight to around 75° C and adding during 5 - 10 minutes under severe stirring 3.4 parts by weight of an aqueous solution of calcium chloride (20.7 % by weight CaCl₂.2aq. ) . This sol is comparable to the product P6 of Example 2 of patent application PCT/EP02/04419. Sol Powder 1 Powder of a sol of amorphous calcium silicate in soluble sodium silicate Product: A spray-dried powder of a sol of amorphous calcium silicate in a sodium silicate solution, having a dry solid content of approx. 80 % by weight. Procedure: Spray-drying of above calcium silicate sol 1.

Sol 2 Sol of amorphous magnesium silicate in a sodium silicate solution Procedure: Heating 68 parts by weight of a sodium silicate solution with a molar ratio Si0₂/Na₂0 of 2.0 and a sodium silicate content of 45.7 % by weight to around 75° C and adding during 5 to 10 minutes under severe stirring 3.58 parts by weight of an aqueous solution of magnesium chloride (18.21 % by weight concentration).

Sol Powder 2. Powder of a dried sol of amorphous magnesium silicate in soluble sodium silicate Product: A spray-dried powder of a sol of amorphous magnesium silicate in a sodium silicate solution, having a dry solid content of approx. 80 % by weight. Procedure: Spray-drying of above magnesium silicate sol 2.

Sol 3 Sol of a silicate based calcium salt in a solution of sodium silicate and sodium carbonate.

Product: A sol of amorphous calcium silicate, most probably also containing calcium carbonate in an aqueous solution of a mixture of sodium silicate and sodium carbonate. This product is an Example according to this invention. Procedure: Mixing 52.8 parts by weight of a sodium silicate solution (molar ratio Si0₂/Na₂0: 2.0 and a dry solid content of 45.7 %) with 7.5 parts by weight of demineralised water and 6.04 parts by weight of anhydrous sodium carbonate. Heating this mixture to approx. 75° C and adding during 5 - 10 minutes under severe stirring 4.2 parts by weight of an aqueous solution of calcium chloride (20.7 % by weight CaCl₂) .

Sol Powder 3 Powder of a dried sol of silicate based calcium salt in a mixture of soluble sodium silicate and sodium carbonate .

Product: A spray-dried powder of a sol of a silicate based calcium salt most probably also containing calcium carbonate in a mixture of soluble sodium silicate and sodium carbonate. The powder having a dry solid content of approx. 80 % by weight ani a concentration of insoluble calcium salts (silicate + carbonate) of approx. 2.1 % by weight.

This product is an Example according to this invention. Procedure: Spray-drying of Sol 3. Sol 4. Sol of amorphous aluminium silicate in an aqueous solution of soluble sodium silicate Procedure: Heating 851.7 parts by weight of a sodium silicate solution (Crystal 0112) to a temperature of around 75° C and adding under severe stirring 58 parts by weight of a concentrated solution of aluminium sulphate in demineralised water (Dry weight: 22.7 wt. %) The weight of the stable sol obtained was 890 g. due to some evaporation. The sol contains 10.4 g. aluminium silicate (1.22 wt. %) . The dry solids content of the sol being 45.2 wt. %.

Sol Powder 4. Powder of a dried sol of amorphous aluminium silicate in soluble sodium silicate Product: A spray-dried powder of a sol of amorphous aluminium silicate in a sodium silicate solution, having a dry solid content of approx. 80 % by weight and an aluminium silicate content of approx. 2.16 wt. %. Procedure: Spray-drying of above aluminium silicate sol 4.

PROCEDURE

In all the following Examples , the same basic procedure was followed i.e. : • 1000 ml. hard water (40° FH) was added to a glass vessel placed in a water bath. • The temperature was kept at 25° C during the tests. • The pH of the reaction mixture was measured and always found to be around 10.7. • Under severe stirring the various components were simultaneously added practically instantaneously.. • The Ca concentration was measured at regular intervals during the tests using a calcium-selective electrode. The calcium concentration is expressed as pCa [-log(Ca)] in analogy with the pH. • All tests were carried out up to 15 minutes. • The pCa values measured are all presented in the table. • All tests were at least carried out in duplicate and demonstrated good reproducibility . Series 1 : Reaction between hard water and sodium carbonate

A Using only sodium carbonate Components added to the hard water: • 509.8 mg. anhydrous sodium carbonate powder.

The example was carried out 4 times. The average results are presented in the table.

Analysis of the results shows that the Ca uptake is delayed by 90 - 120 seconds, due to the delay in crystal-nucleation of calcium carbonate. The results also demonstrate, that even when an excess of 20 % of sodium carbonate is used in relation to the hardness calcium ions, a final pCa is reached of only around 3.8

A"_rep. As Example A, but using the double amount of sodium carbonate

The same procedure was followed as in 1A. However, after 15 minutes a second portion of 509.8 mg sodium carbonate powder was added. The results presented in the table show that using a 140 % excess of sodium carbonate gives a higher final pCa of around 4.6

B Using sodium carbonate and calcium carbonate as seed. Components added to tte hard water: • 509.8 mg anhydrous sodium carbonate powder • 200 mg calcium carbonate powder. The example was carried out in duplicate.

The average results are presented in the table..

The Ca uptake is much less delayed (20-25 seconds) , due to the addition of the crystallisation seeds (calcium carbonate powder) .

Varying the quantity of calcium carbonate seeds shows, that a delay of approx. 20-25 seconds seems a minimum reached using appprox. 200 mg. calcium carbonate in this test.

B"_rep, As Example B, starting with water of pH = 10.7 and predosing of the seeds . Experiment B was repeated with two small adjustments, i.e.: • The hard water pH was adjusted to 10.7 using a solution of 1 Molar NaOH. • The calcium carbonate seeds were added first to the hard water (10O0 ml, pH: 10.7) under stirring. After 5 min. further stirring, the sodium carbonate was added. The pH was again around 10.7 during the test. The purpose of this test was to assess whether the higher initial pH had an influence on the pCa measurements during the test and whether the seeds needed some time for activation in the alkaline liquor. There was no difference at all between the results of Example B and B'_rep. The delay in Ca-uptake was again 20-25 seconds.

C Using sodium carbonate, calcium carbonate seeds and soap. Components added to the hard water: • 509.8 mg anhydrous sodium carbonate powder • 200 mg calcium carbonate powder • 50 mg soap (sodium stearate) dissolved in warm 0.01 N NaOH The example was carried out in duplicate. The average results are presented in the table. The delay in Ca uptake (25 seconds) is only slightly more than in test B due to the possible poisoning of the seeds. This delay is slightly more pronounced than analysed, due to the fact, that the soap contributes to the calcium uptake by approx. 0.1 unit of pCa. This effect was confirmed by carrying out separate experiments with only sodium carbonate and soap. These experiments showed that the addition of soap to sodium carbonate in the absence of silicate only causes a completely parallel upwards lift of the total curve depending on the quantity of soap added. This means that sodium stearate has practically no influence on the crystallisation of calcium carbonate using pure sodium carbonate in the absence of calcium carbonate seeds. Calcium stearate is therefore not at all a seed for the calcium carbonate formation. It can be concluded on the contrary however, that the soap seemed to have the opposite effect, showing that (after correction for the uptake of calcium by the soap) the soap acted indeed as a weak poison for the calcium carbonate seeds formed and that the main effect was a lowering of the pCa during the first 2 minutes.

Series 2 Reactions between hard water with sodium carbonate in the presence of sodium silicate

D Using sodium carbonate powder and sodium silicate powder Components added to the hard water: • 407 mg anhydrous sodium carbonate powder • 117.2 mg sodium silicate powder

The example was carried out in duplicate. The average results are presented in the table. The Ca uptake (70 seconds) is also delayed here, although slightly less than in Example A, This confirms earlier findings, that the presence of soluble silicate does not seriously influence the crystallisation of the calcium carbonate. There is only a small influence in this case. The pCa values remain below the curves found in Series 1. The reason for this being, that the total number of Moles of sodium silicate and sodium carbonate is less than the number of Moles of sodium carbonate in Series 1, resulting in a lower total calcium uptake capacity in this series. For a real match 146.4 mg sodium silicate would have been required.

E Using sodium carbonate powder, sodium silicate powder and calcium carbonate as seed. Components added to the hard water: • 407 mg anhydrous sodium carbonate powder • 117.2 mg sodium silicate powder • 200 mg calcium carbonate powder.

The example was carried out in duplicate. The average results are presented in the table. The Ca uptake is much less delayed (20 seconds) due to the addition of the crystallisation seeds (calcium carbonate powder) .

F Using sodium carbonate powder , calcium carbonate seed and soap ■ Components added to the hard water: • 407 mg anhydrous sodium carbonate powder • 117.2 mg sodium silicate powder • 200 mg calcium carbonate powder • 50 mg soap (sodium stearate) dissolved in warm 0.01 N NaOH. The example was carried out in duplicate. The average results are presented in the table. As the dosing of the sodium silicate and sodium carbonate was not corrected for the calcium uptake of soap also these pCa values were lifted when compared to Examples D and E (as was the case in Example C compared to Examples A and B) . Hardly a poisoning effect of the seeds by soap could be established. Corrected pCa values show however, that the corrected pCa was lower during the first minute compared to test E.

Series 3 Reactions between hard water with sodium carbonate in the presence of a sol of a calcium silicate in sodium silicate (Sol 1) .

G_ Using sodium carbonate powder and the dried sol 1 (Sol Powder l∑

Components added to the hard water : • 407 mg anhydrous sodium carbonate powder • 117.2 mg powder of a dried sol of calcium silicate in sodium silicate (Sol Powder 1) The example was carried out in duplicate. The average results are presented in the table. The Ca uptake is also delayed here up to around 70 seconds. This confirms earlier findings, that calcium silicate even when extremely dispersed and with an extremely large surface area is not a suitable seed for the crystallisation of calcium carbonate

H Using sodium carbonate powder, the dried sol 1 (Sol Powder 1) , and calcium carbonate seeds .

Components added to the hard water: • 407 mg anhydrous sodium carbonate powder • 117.2 mg powder of a dried sol of calcium silicate in sodium silicate (Sol Powder 1) • 200 mg calcium carbonate powder. The example was carried out in duplicate. The average results are presented in the table.

The Ca uptake is hardly delayed (22 seconds) any more due to the addition of the crystallisation seeds (calcium carbonate powder). This confirms, that calcium carbonate is a good seed for the crystallisation of calcium carbonate, while calcium silicate is not.

1_^ Using sodium carbonate powder, the dried sol 1 (Sol Powder 1) , calcium carbonate seeds and soap. Components added to the hard water: • 407 mg anhydrous sodium carbonate powder • 117.2 mg powder of a dried sol of calcium silicate in sodium silicate (powder 1) • 200 mg calcium carbonate powder. • 50 mg soap (sodium stearate) dissolved in warm 0.01 N NaOH The example was carried out in duplicate. The average results are presented in the table. As no correction was made for the calcium uptake of soap the curves were again lifted when compared with Examples G and H. This made it again more difficult to exactly quantify the poisoning effect by the soap (delay measured: 23 seconds) .

Series 4 Reactions between hard water with sodium carbonate in the presence of a sol of a silicate based calcium salt in a sodium silicate/ sodium carbonate mixture (Sol 3) .

J_ Using sodium carbonate powder and the dried sol 3 (Sol Powder 3) of a silicate based calcium salt in a mixture of sodium silicate and sodium carbonate. Components added to the hard water: • 407 mg anhydrous sodium carbonate powder • 117.2 mg powder (powder 3) of a dried sol of calcium silicate/calcium carbonate in a mixture of sodium silicate and sodium carbonate. The example was carried out in duplicate. The average results are presented in the table. The Ca uptake is surprisingly much less delayed here (only 40 seconds) , when compared with the other Examples, carried out in the absence of calcium carbonate crystallisation seeds, i.e.: Examples A, D and G (delays 70 - 100 seconds) . This reduction of the initial delay of calcium carbonate formation was a surprising and very interesting finding, as it is significantly superior over these previous tests.

K Using sodium carbonate powder, calcium carbonate as seed and the dried sol 3 (Sol Powder 3) of a silicate based calcium salt in a mixture of sodium silicate and sodium carbonate. Components added to the hard water: • 407 mg anhydrous sodium carbonate powder. • 200 mg calcium carbonate powder. • 117.2 mg powder 3 of a dried sol (Sol 3) of a silicate based calcium salt (i.e.: probably calcium silicate/calcium carbonate) in a mixture of sodium silicate and sodium carbonate. The example was carried out in duplicate. The average results are presented in the table. The Ca uptake is again only delayed by approx. 20 seconds. Comparing the results of Examples J and K is very interesting, as it shows, that the addition of seeds of calcium carbonate did not show a large improvement in crystallisation of calcium carbonate. A delay of 20 seconds seemed a minimum delay achievable in these Examples.

L Using sodium carbonate powder, calcium carbonate seeds, soap and the dried sol 3 (Sol Powder 3) of a silicate based calcium salt in a mixture of sodium silicate and sodium carbonate, Components added to the hard water: • 407 mg anhydrous sodium carbonate powder. • 200 mg calcium carbonate powder. • 117.2 mg powder (Powder 3) of a dried sol of calcium silicate/calcium carbonate in a mixture of sodium silicate and sodium carbonate. • 50 mg soap (sodium stearate) dissolved in warm 0.01 N. NaOH The example was carried out in duplicate. The average results are presented in the table. Again no correction for the calcium uptake of soap was made lifting also these pCa values. After correction of the curves the possible poisoning effect by soap could be better assessed. After this correction the pCa values of examples K and L seem to coincide, indicating, that there is no poisoning effect at all on the delay. Comparing this result of Example L with Examples C, F, I and P there is an indication, that these sols according to the invention also seem to offer a better resistance against seed poisons. Series 5 Reactions between hard water with sodium carbonate in the presence of a sol of aluminium silicate in sodium silicate (Sol 4) .

N_ Using sodium carbonate powder and the sol (Sol 4) of aluminium silicate in an aqueous sodium silicate solution. Components added to the hard water: • 510 mg anhydrous sodium carbonate powder • 199 mg of a sol of aluminium silicate in sodium silicate (Sol 4) The example was carried out in duplicate. The average results are presented in the table. The Ca uptake is also delayed in this Example (in the absences of added calcium carbonate seeds) to around 70 seconds. This confirms earlier findings, that aluminium silicate even when in an extremely dispersed form and with an extremely large surface area does not function as an efficient seed for the crystallisation of calcium.

O Using sodium carbonate powder, an aluminium silicate sol (Sol 4), and calcium carbonate seeds. Components added to the hard water: • 510 mg anhydrous sodium carbonate powder • 209 mg of a sol of aluminium silicate in sodium silicate (Sol 4) • 198 mg calcium carbonate The example was carried out in duplicate. The average results are presented in the table. The Ca uptake is delayed slightly more (approx. 30 seconds) , when compared with the comparable Examples carried out in the presence of the added calcium carbonate seeds. This reduction in crystallisation delay from 70 seconds to 30 seconds again confirms, that calcium carbonate is functioning as a seed for the crystallisation of calcium carbonate, while aluminium silicate is not. A possible explanation for the observation that in this system the calcium carbonate seeds are less efficient is the fact that the aluminium sulphate was of a technical grade and already visibly containing impurities (slightly brown colour) . These impurities probably act as seed poisons. P Using sodium carbonate powder, an aluminium silicate sol (Sol 4) , calcium carbonate seeds and soap. Components added to the hard water: • 509 mg anhydrous sodium carbonate powder • 202 mg of a sol of aluminium silicate in sodium silicate (Sol 4) • 202 mg calcium carbonate • 50 mg sodium stearate dissolved in warm 0.01 N NaOH The example was carried out in duplicate. The average results are presented in the table. The crystallisation of calcium carbonate was delayed by approx. 47 seconds, showing, that in this case there is a much higher poisoning effect caused by the addition of the soap. This is probably caused by the impurities in the aluminium sulphate in combination with the soap.

Discussion on Examples • Examples A, D, G, J and N show, that the initial delay of the Ca uptake due to the time needed to produce crystallisation nuclei is strongly reduced in Example J from 70 - 100 seconds to 40 seconds. It is therefore concluded, that the sol in Example J, being a product according to the invention is providing effective seeds for the crystallisation of calcium carbonate . • Examples B, E and H show that addition of 200 mg calcium carbonate as seeds in this model test, in the absence of seed poisons, reduces the initiation phase to approx. 20 seconds. To match the seeding effect of the sol according to the invention (Example J) approx. 100 mg calcium carbonate seeds is required. • Examples C, F, I and L show, that sodium stearate is not a good model compound to demonstrate seed poisoning. Only minor increases of the initiation phase are realised by the soap addition. Comparing these increases in initiation time it seems apparent, that the increase is maximal in the experiments C and F, while there is absolutely no increase in Examples and probably no increase in Example I either, where sols of calcium silicate or silicate based calcium salts were present. Sol particles according to this invention and to WO 02/086042 apparently protect seeds against poisoning. • Examples 0 and P indicate, that the sol containing aluminium silicate particles does not protect seeds. Probably due to the impurities in this sol, acting as seed poison. • From the Examples it can be concluded, that sols according to WO 02/086042 do not function as seeds, but do protect calcium carbonate seeds added separately against seed poisoning, thus improving the efficiency of seeds added in a practical wash situation, where seed poisons are generally present. • Sols according to this invention do not only protect seeds present in a practical situation, where seed poisons are present, but surprisingly also provide themselves effective seeds, meaning that no additional seeds are required or that much less seeds will be additionally needed. • The Examples using soap also demonstrate the known effect of soap in the wash, i.e.: the fast reaction of the soap with calcium and/or magnesium ions. This being one of the main reasons for the well known problems caused by the slower reaction of several builders in the wash like carbonates. During the initial phase the calcium and magnesium ions can react with other faster reacting compounds like soap, causing various negative effects, e.g.: reduced detergency, part of the surfactants being inactivated, and calcium and magnesium soap deposition on fabrics and machine parts (e.g.: on heating coils) .

Acknowledgement I thank Mr. Remo Kanders of the firm Ineos Silicas B.V. Eijsden, the Netherlands, for skillfully carrying out all above experiments and Mr. Peter Schouren, R&D manager of Ineos Silicas for his support.

Table 1 : Results of Examples A- I ,

Claims

C L A I M S

1. Method for the preparation of a suspension, in particular a sol, comprising amorphous small particles of a salt selected from the group consisting of a silicate based calcium salt, a silicate based magnesium salt, a silicate based strontium salt, a silicate based aluminium salt, a silicate based barium salt, a silicate based zinc salt, a silicate based zirconium salt, or a combination thereof, the method comprising the step of:

- mixing an aqueous solution of a salt selected from the group consisting of a salt of calcium, magnesium, strontium, aluminium, barium, zinc and zirconium or a mixture thereof with a soluble alkali metal silicate salt and a soluble carbonate salt.

2. Method according to claim 1, wherein the soluble ailkali metal silicate salt and the soluble carbonate salt are combined before mixing with the solution of a salt selected from the group consisting of a salt of calcium, magnesium, strontium, aluminium, barium, zinc and zirconium or a mixture thereof.

3. Method according to claim 1, wherein 50 - 90% of the solution of a salt selected from the group consisting of a sa.lt of calcium, magnesium, strontium, aluminium, barium, zinc and zirconium or a mixture thereof is mixed with the soluble alkali metal silicate salt, which is subsequently mixed with the soluble carbonate salt, and thereafter with the remainder 50 - 10% of the solution of: a salt selected from the group consisting of a salt of calcium, magnesium, strontium, aluminium, barium, zinc and zirconium or a mixture thereof.

4. Method according to claim 1, wherein the soluble alkali metal silicate salt and the solution of a salt selected from the group consisting of a salt of calcium, magnesium, strontium, aluminium, barium, zinc and zirconium or a mixture thereof are combined before mixing with the soluble carbonate salt. 5. Method according any of the preceding claims, wherein the soluble alkali metal silicate salt has a molar ratio Si0₂/M₂O between 1.0 and 4.0, preferably between 1.

5 and 3.3, more preferably loetween 1.8 and 2.8; M being selected from the group consisting of sodium and potassium or a mixture thereof.

6. Method according any of the preceding claims, wherein the soluble carbonate salt has a molar ratio C0₂/MO between 0.5 and 3.0; M being selected from the group consisting of sodium and potassium or a mixture thereof.

7. Method according to any of the preceding claims, wherein the mixing is performed at a temperature > 20 °C, preferably > 40°C, more preferably > 60°C, even more preferably at 65-100°C, most preferred at 70-85°C.

8. Method according to any of the preceding claims, wherein the suspension is dried.

9. Intermediate product obtainable by the method according to any of the preceding claims.

10. Intermediate product according to claim 9, wherein the product comprises amorphous small particles, at least 99 % by weight of which having a particle size below 10 micrometer; preferably more than 90 % by weight having a particle size of below 2 micrometers; more preferably 85 % by weight having a particle size of below 1 micrometer; more preferably 85 % by weight having a particle size below 0.2 micrometers; even more preferably more than 80 % by weight having a particle size below 0.1 micrometers; and most preferably 70 % by weight having a particle size of below 0.05 micrometers.

11. Intermediate product according to claim 9 or 10, wherein the intermediate product is in the form of a suspension, in particular a sol.

12. Intermediate product according to any of the preceding claims 9-11, wherein the intermediate product is in a dried form, in particular in the form of a powder or granules.

13. Intermediate product according to claim 12, wherein the powders or the granules have been milled to a powder having a particle size below 2000 micrometer; preferably 90 percent by weight of the powder having a particle size of below 8O0 micrometer; and most preferably 90 percent by weight of the powder having a particle size below 600 micrometer.

14. Intermediate product according to claims 12 or 13, wherein 5 it has been compacted or granulated, preferably having a bulk density of > 600 g/1, more preferably 800 - 1200 g/1.

15. Intermediate product according to claim 13 or 14, wherein the granules obtained are milled and sieved to a suitable particle

10 size, preferably between 25 and 1200 micrometer; more preferably 90 percent by weight of the granules having a particle size of between 25 and 800 micrometer and most preferably 90 percent by weight of the granules having a particle size of between 50 and 600 micrometer.

15 16. Use of the intermediate product according to any of the preceding claims 9-15 for the preparation of a detergent composition, in particular a detergent composition intended for fabric washing, (mechanical) dish washing or industrial cleaning.

20 17. Detergent composition comprising at least 0.01 % by weight of the intermediate product according to one of the preceding claims 9-15.

18. Detergent composition according to claim 17 comprising < 25 25 % by weight of the intermediate product, preferably < 10 % by weight, more preferably < 5 % by weight.