Process for producing a percarbonate

IS 2 175 387 T3

DESCRIPTION

Compositions containing sodium percarbonate.

This invention relates to sodium percarbonate and to compositions containing it, especially detergent compositions that additionally contain one of its constituents that interacts destructively with sodium percarbonate.

Detergent compositions, and specifically particulate detergent compositions intended for general purposes of domestic fabric laundering, or for special uses such as disinfection of linens or dishwashing, often contain in addition one or more surfactants, a builder, a bleach, and optionally fillers / processing aids and minor amounts of a number of other adjuvants, including one or more chosen ooptic bleach, complexing agents, perfumes, and colorants. Traditionally, the builder has been selected from inorganic phosphates such as sodium tripolyphosphate in view of the beneficial properties of phosphates in fabric washing, but phosphates have been shown to produce or contribute to eutrophication, and a source of phosphates is effluent from domestic or industrial fabric washing. Consequently, and in response to increasingly stringent legislation in different countries, the detergent industry in recent years has sought alternatives to phosphates, of which an important class of substitution builders comprises zeolites.

The bleach constituent typically comprises a peroxo compound, of which a favored example comprises sodium carbonate peroxyhydrate in view of its solubility and other characteristics. This compound has been commonly called sodium percarbonate, and is thus called here. However, sodium percarbonate can interact destructively with other detergent constituents, resulting in the progressive decomposition of percarbonate, and therefore its loss of bleaching power during storage and transport of the composition, and the problem is especially evident when the detergent builder comprises zeolites.

A number of proposals have been made to overcome or ameliorate the problem of sodium percarbonate breakdown in zeolite-enhanced detergent compositions. In general, the proposals refer to two methods. In a method, exemplified by Unilever EP-A-0451893, a sodium percarbonate particle size distribution is selected according to a given formula. Indeed, the formula favors a mean particle size of at least 400 µm and a narrow particle distribution. This method simply uses the gross external dimensions of the percarbonate to indicate which are higher and which are lower particles to use. However, sodium percarbonate generally has a porous or irregular outer layer, so the gross dimensions do not directly control the effective surface area of ​​the percarbonate. The regularity and porosity of the outer surface of sodium percarbonate varies depending on its method of manufacture, and this is an additional and very important factor that directly affects the effective surface area and stability of the percarbonate.

A second and frequently described method of improving the stability of sodium percarbonate is to coat the surface of the percarbonate with a surface layer of material that interposes phosphically between the surface of the percarbonate and any other particulate constituents of the composition. The effectiveness of the coating to retard or improve the rate and extent of decomposition of the percarbonate depends on the nature of the material used for the coating and the integrity of the coating. Although a number of coating materials that are beneficial in retarding decomposition of zeolite-enhanced detergent compositions, including particularly coatings containing sodium borates, have been described in US-A-4526698 by Kao Soap, they do not teach the reader anything. on the inherent stability of uncoated percarbonate. Similarly, in WO 95/15291 to Kemira, the use of carbon dioxide gas in contact with wet percarbonate during the coating operation is described to improve the resulting stability of the resulting coated percarbonate. As with the Kao Soap disclosure, no teaching is provided on the stability of uncoated percarbonate.

The continuing desire to incorporate both zeolites and sodium percarbonate into a detergent composition, and especially concentrated or ultra-concentrated detergent compositions, means that there is still a need to find more and / or better ways to improve percarbonate stability and / or determine how to properly select Of the different methods of manufacture of sodium percarbonate, the product that presents improved or optimized stability.

However, in at least some parts of the world, a significant fraction of the compositions

ES 2 175 387 T3 washings or bleach additive compositions are improved with a majority proportion of non-zeolite builders or even without any zeolite builder, so that it would also be commercially advantageous to improve or optimize the stability of the sodium percarbonate also incorporated in said compositions. .

A first objective of at least some aspects of the present invention is to provide different and / or improved detergent compositions containing both sodium percarbonate and a zeolite.

Another objective of the present invention, at least in certain other aspects, is to identify a method for selecting sodium percarbonate that is intrinsically suitable for incorporation into improved compositions.

According to the present invention, a detergent composition is provided containing a zeolite builder and sodium percarbonate, characterized in that the sodium percarbonate intrinsically has an average particle size of 500 to 1000 μm and not more than 20% by weight below 350 μm, and has a moisture absorption when measured in a test performed in a humid room, with a relative humidity of 80% and 32 C after 24 hours, not more than 30 g / 1000 g of sample.

Here, "intronsically" when used in conjunction with sodium percarbonate, or "intronsically sodium percarbonate", both indicate dry sodium percarbonate, which has been obtained by a crystallization or other manufacturing process without a subsequent coating or surface treatment interposing a layer. of sodium non-percarbonate material between itself and other constituents of the composition. It was recognized that the properties of particulate sodium percarbonate can be modified by subsequent treatments, but that it is still advantageous to select as the core material sodium percarbonate having inherently good stability.

According to another aspect, there is provided a process for selecting sodium percarbonate for incorporation in a composition containing builder, characterized by carrying out in any order the steps of:

1) measure your particle size distribution, determine your mean particle size, and the fraction by weight below 350 μm, and from step 1 reject material that has a mean particle size outside the range of 500 to 1000 µm or containing more than 20% by weight below 350 µm; Y

2) measure the extent to which moisture is absorbed by the material in a test carried out for 24 h at 32 ° C, and 80% relative humidity, and reject the material that absorbs more than 30 g of moisture per 1000 g of material, the retained material fulfilling the intrinsically acceptable standards for sodium percarbonate, in relation to its particle size and moisture absorption.

By selecting the intronsic sodium percarbonate that simultaneously has a desirable particle size distribution, and adequate moisture absorption in the specified tests, one can identify the sodium percarbonate that has superior stability in an improved composition, such as especially a detergent composition. enhanced with zeolite, when compared for example to commercially available uncoated percarbonate incorporation that does not meet or meets only one of the selected parameters.

It was recognized that various soda percarbonate products having the same or similar particle size distribution, but widely different moisture absorptions, can be produced and isolated by choosing the manufacturing procedure and by the proper selection of working conditions / parameters within of the chosen manufacturing process. Said various products have variable stability against decomposition in an improved composition, and especially in a zeolite-enhanced detergent composition. Some will be better and some will be worse, and the choice of which sodium percarbonate is best to use can be made using the two test methods of the invention.

Without being bound by any particular theory or belief, it is considered probable that the moisture absorption measured by the test is indicative of the extent of irregularity and / or porosity of the potassium percarbonate that it presents to the atmosphere, as long as the particle size distribution is indicative of the physical contact between the particulate constituents of the composition, and that when considered together rather than individually, both trials present a clear basis for selecting sodium percarbonate which has intrinsically good stability in the presence of the zeolite builder, and indeed

ES 2 175 387 T3 also in the presence of other enhancers.

It is preferable that the sodium percarbonate particles fall substantially in the range of 250 to 1250 µm and particularly that at least 80%, and advantageously at least 95% by weight of the particles fall in the range of 350 to 1000 µm. It is particularly convenient to use sodium percarbonate having an average particle size of 550 to 850 µm, and in a series of preferred embodiments of 600 to 800 µm. A product that has an average particle size of at least 600 µm and especially at least 650 µm and a path of 0.9 to 1.2 will often meet the criteria for particle size without carrying out further classification. From the point of view of percarbonate stability, it is desirable to avoid or minimize the proportion of relatively small particles, such as particles below 350 µm, and particularly below 250 µm. Relatively large particles, such as over 1000 µm in diameter do not impair stability, but can be segregated from the minor constituents of the compositions to a greater extent.

Sodium percarbonate particle size distribution can be determined by a standard method of sieving a representative sample of the material through a set of sieves of known decreasing aperture, and weighing the fraction of material retained on each sieve. As the number of sieves increases, the precision of the measurement increases. In an alternative method of measurement, the particulate product is passed through a beam of light from a laser and the resulting scattered light is analyzed, for example using a particle size analyzer available under the trade name Malvorn 2600 C.

The particle size distributions listed here can be obtained by one or more of the following methods. When using a crystallization process, one can use external sorting, for example dry percarbonate, and / or an internal built-in sorter attached to the crystallizer, and sorting the percarbonate particles in a liquid medium, to isolate the required fraction or make a convenient range of percarbonate particles respectively. For example, a product having an average particle size, of dried particles, in the range of 500 to 700 µm can be easily obtained from a dried product of a conventional "wet" manufacturing process, by sieving and substantially excluding all particles below a specified sieve size, such as 350 μm, thus leaving a fraction typically ranging from 350 to about 850 μm, and a maximum fraction of about 500 to 600 µm. By sieving to exclude product below a larger sieve size, for example 500 µm, a product with a larger average particle size, for example 600 to 700, can be obtained. Alternatively or additionally, the excess particles of a larger size such as 1250 to 1000 µm, they can be separated to leave a narrower range. It would also be recognized that the particle size distribution of the product obtained in the manufacturing processes can be varied by controlling the process parameters. Therefore, in a crystallization process, by controlling the nucleation rate relative to growth in the crystallizer, and avoiding or minimizing the introduction of preformed nuclei, the average particle size of the resulting product can be increased.

In another variation, the size distribution of sodium percarbonate particles having an average particle size below 500 μm can be increased to within the convenient range by a granulation / agglomeration process of the particles, typically with the aid of an aqueous solution. of a known agglomeration / granulation aid for alkaline materials, sprayed onto the percarbonate in conventional apparatus, such as a granulation container. For example, water soluble coating agents for sodium percarbonate, such as silicate, may be suitably used under the proper process conditions for the granulation to bind the percarbonate particles together than to simply form a coating.

It is especially preferable to use crystallized sodium percarbonate that has been produced by a process in which there is a classifier integrated with the crystallizer, and it operates in such a way that particles above and below a desired minimum size are separated outside the classifier, the particles large mais are recovered as a product, while the very small particles are recycled to the crystallizer where they can grow as a result of additional sodium percarbonate deposition from the solution, typically by adding saline reagent to the saturated or supersaturated sodium percarbonate solution in the crystallizer, and the increased particles become to flow to the classifier. Such combined classifiers / crystallizers are particularly beneficial in that by proper control of operation, the particle size can be controlled during manufacture, rather than having to use an external and therefore additional classifying procedure. The product normally has a particle distribution that is similar to "normal", the dispersion of which depends on the type of installation used. Often has a stroke of about 0.6 to about

IS 2 175 387 T3

0.9. The product normally has at least 80% and frequently at least 90% by weight of its particles within the range of +/- 50% of the mean particle size, with a mean particle size above 600 to 1000 and in many cases 650 to 850 μm.

Another process capable of producing sodium percarbonate with the convenient particle size range, comprises a crystallization process that works with the ratio of hydrogen peroxide to sodium percarbonate maintained substoichiometric, and particularly in the range of 0.8-1.2: 1, being the mother liquor in the recycling to the crystallizer less than saturated in carbonate, and the crystallization being carried out without the addition of saline reactive agent.

Advantageously, the process that avoids a saline reactive agent such as sodium chloride which readily coprecipitates with sodium percarbonate, and particularly the processes that avoid the saline reactive agent, can produce product with a high purity, for example with a COD (content of available oxygen) of at least 14.5% and in some embodiments a DOC of at least 14.8%.

Said crystallization processes above can be carried out naturally using stabilizers and crystal habit modifiers such as sodium silicate, polyphosphoinic acids, phosphates and homo or copolyacrylates in the art recognized manner, although with greater benefit when no saline reactive agent is used. , so that residual peroxide concentrations may be higher than in chloride saline reagent procedures. In many cases, the resulting product has a smooth round shape that encourages tight packing and allows its bulk density to drop in the region of 800 to 1100 g / 1000 g in a standard free-flowing bulk density test.

Alternatively, when, for example, particulate sodium percarbonate is obtained by evaporation of a carrier fluid of a sodium percarbonate solution, or solutions of the reactants to form sodium percarbonate in situ, which are sprayed onto a bed of sodium percarbonate particles , for example fluidized by an ascending stream of inert drying gas, for example air, The process can be continued until the desired particles are obtained having at least a minimum size which provides the mean particle size with at least the widest range of 500 to 1000 µm. In said fluidized bed procedure, the working conditions can be selected that reduce or minimize the creation of nuclei by physical disintegration in situ of particles existing in the bed, and minimize the introduction of externally produced nuclei, thus promoting the formation once again. of a product that has a larger particle size.

A second important characteristic of the sodium percarbonate used in the compositions of the invention is the extent / speed with which it absorbs moisture from a humid atmosphere. Here, specifically including the exemplified and comparison compositions, the ability of sodium percarbonate to absorb moisture is measured by the following test.

A 9 cm diameter petri dish with 1 cm depth at the rim is accurately weighed on a 4 decimal scale, (W1). A sample of dry sodium percarbonate (approximately 5 g) is placed in the petri dish, shaken moderately to generate a uniform layer of particles along the base of the plate and reweighed on the same balance, (W2) . The sample in the petri dish is stored in a room approximately 3 m high, wide and long, in an atmosphere maintained for a period of 24 hours at 32 ° C, with a thermostat-controlled heater, and a relative humidity (RH ) of 80% by introducing a fine water droplet spray under the control of a humidity detector, and weighing on the same balance, (W3). Samples are protected with a sprayer screen.

The moisture absorption of sodium percarbonate is calculated as follows:

Moisture absorption (g / kg) =

1000 x (W3 - W2) (W2 - W1)

Depending on your method of manufacture, the extent of moisture absorption by sodium percarbonate in the test can vary over a very wide range, from a low amount that is below 10 g / 1000 g to 1-5 g. / 1000 g to an amount that is in the range of 100 to 200 g / 1000 g. These latter products are outside the scope of the present invention. Other manufacturing methods can generate products that have a moisture absorption between 15 and 30 g / 1000 g in the test. Its use in zeolite compositions is in accordance with the present invention, although the selection of products with lower moisture absorption (ie, up to 15 g / 1000 g) or especially the lowest is preferred.

IS 2 175 387 T3

The extent of moisture absorption has been found to be influenced by substances, such as saline reactants, that are used to promote percarbonate crystallization. Traditionally, the most important saline reactive agent has been sodium chloride, because it is readily available and has been very effective in promoting crystallization, but it has now been found, disadvantageously, that its use tends to promote the extent of moisture absorption. Consequently, and in order to control the moisture absorption of the intrinsic sodium percarbonate, it is especially desirable that the proportion of sodium chloride in the saline reagent is controlled to provide at least no more than a minor fraction of the sodium (on a basis molar), such as for example, not more than 10%. It is particularly convenient to use a saline reactant essentially chloride-free, ie with no more than one level of impurity. In some particularly preferred processes for obtaining sodium percarbonate having the desirable low moisture absorbency characteristic, sodium sulfate is used as the saline reactant. In other processes especially suitable for producing a product having low moisture absorption, crystallization can be carried out in the absence or substantially in the absence of any added saline reactant, for example by omission of the saline reactive agent of the procedure described in EP-A-0703190.

Accordingly, it will be recognized that if a coating agent is used, at least in part, to granulate intrinsically acceptable sodium percarbonate to increase its mean particle size to about 500 μm, corresponding restrictions on the presence of chloride in the agent are desirable. Coating.

It will be recognized that it is especially advantageous for the manufacturer of sodium percarbonate to use a manufacturing process for sodium percarbonate, which can be controlled to produce a product that simultaneously has low moisture absorption and a narrow particle size distribution, with a medium in the region of 500 to 1000 μm. Said manufacturing process uses in combination the crystallization of the percarbonate in an integrated crystallizer / classifier as described herein, and the use of sodium sulfate or other salt other than sodium chloride as a saline reactive agent. Indeed, within the class of especially suitable procedures are those in which the saline reagent is omitted.

One type of apparatus that can be used to advantage to produce sodium percarbonate having inherently acceptable properties, provided that the saline reagent, if any, is properly chosen, is described in Solvay Interox EP-A-703190 SA

The detergent composition of the present invention often contains sodium percarbonate meeting the average particle size combination of 500 to 1000 μm, and moisture absorption of not more than 30 g / 1000 g in the test, in an amount of at minus 2% and in many cases at least 5% by weight. It is usually no more than 40% and in many cases up to about 25% by weight of the composition.

It will be recognized that sodium percarbonate having the aforementioned combination of defined particle size and moisture absorption characteristics, can be incorporated as such into the detergent composition with zeolite or other improved detergent composition, or optionally can serve as a convenient base and preferred for coating, further combining its inherent stability with that imparted by a coating. The amount of such coating is usually selected in the range of 0 to 20% w / w based on sodium percarbonate, and a convenient amount is often selected in the range of 1 to 5% w / w. It is especially desirable to select the coating material so that it increases rather than decreases the stability improvement achieved by the inherent sodium percarbonate. Accordingly, it is preferable to use a coating that excludes a soluble halide, such as especially sodium chloride, from the coating, or to use no more than an acceptable higher amount, such as no more than about 2.5% based on the sodium percarbonate. Subject to the chloride-related restriction, the coating materials often advantageously comprise one or more materials selected from the following: alkali and / or alkaline-earth metal, particularly soluble sodium or magnesium, salts of mineral acids or other acids. inorganic substances and especially sulfate, carbonate, bicarbonate, phosphate and / or polymeric phosphates, silicates, borates and the corresponding boaric acids. The coating may additionally or alternatively contain water-soluble acids and salts of metal chelating agents such as of the aminoethylene polycarboxylates and aminoethylene polymethylene phosphonates classes, including the well-known EDTA, DTPA, EDTMPA and DTPMPA, and / or carboxylic or hydroxycarboxylic acids. chelators, such as citrate, tartrate, or gluconate. Other constituents can include fatty acids (eg up to C20) and / or the corresponding amides.

IS 2 175 387 T3

Coating agent combinations of interest include carbonate / sulfate, and boric acid or borate with sulfate and the combination of a) sulfate, carbonate / sulfate, bicarbonate, boric acid, or borate alone or with sulfate, citrate, or citrate / sulfate. , gluconate or gluconate / sulfate, with b) silicate and / or a metal carboxylate or phosphonate chelating agent.

A wide variety of zeolite builders, sometimes alternatively referred to as aluminosilicate builders, can be incorporated into the compositions of the invention. Suitable zeolites typically demonstrate substantial calcium (or other alkaline earth metal) ion exchange capacity (i.e. water hardness), expressed as CaCO3 equivalent to at least 150 mg CaCO3 per g, and for most zeolites their hardness exchange capacity is preferably 200 to about 350 mg CaCO3 equivalent per g.

A number of such zeolites often obey the general emporic formula M2 [(AlO2) z (SiO2) y] xH2O, in which M represents an alkali metal, preferably sodium, and zy are both at least 6, and the molar ratio of y: z is 1: 1 to 2: 1, and x is at least 5 and preferably 10 to about 280. Many of the zeolites are hydrated, and contain up to about 30% by weight of water, such as about 10 to approximately 25% water bound within the material. Zeolites can also be amorphous, although most preferred zeolites are crystalline.

Although some aluminosilicates are natural, most are synthetic. Suitable known crystalline zeolites of well-known structure and formula include zeolite A, zeolite X, zeolite B, zeolite P, zeolite Y, zeolite HS, and zeolite MAP.

The proportion of zeolite in the composition is often at least 5%, and in many cases at least 10% by weight. Typically it is not more than about 60%, often not more than 50%, and in many cases not more than 40% by weight of the composition.

The zeolite for use in the present invention can be prepared in a way that reduces or minimizes subsequent bleach attack on a composition, such as by controlling the moisture content, preferably below the equilibrium level, as described for example in WO document

95/05445.

It was understood that, in a modification of the invention, although the present invention in one aspect is primarily directed to compositions containing one or more zeolite builders together with the selected percarbonate, a similar benefit can be observed in terms of greater percarbonate stability, selected percarbonate in the same way to use together with amorphous silicates or especially in layers, that substitute for zeolite within the same proportions by weight, although on a smaller scale as corresponds due to their more benign interaction with percarbonate. Such crystalline layered silicates often obey the emporic formula Na2SixO2x + 1 and H2O or the corresponding compounds in which a sodium ion is substituted for hydrogen, where x is selected from the range 1.9 to 4, and y is selected in the range 0 to 20, as described for example in EPA-164514. In the modification of the invention, said lamellar silicates are used in the absence of zeolites.

The detergent compositions of the present invention usually contain one or more surfactants, often present in total in an amount of 2 to 40% and particularly 5 to 25% by weight.

Surfactants for incorporation into solid compositions of the present invention can be selected from particulate or flake anionic, cationic, nonionic, zwitterionic, amphoteric and ampholotic surfactants, and may be natural or synthetic soaps. A number of suitable surfactants are described in chapter 2 of "Synthetic Detergents" by A. Davidsohn and BM Milwidsky (6^to edition) published in 1978 by George Godwin Ltd and John Wiley & Sons. Without being limited to these surfactants, representative subclasses of anioine surfactants are carboxylic acid soaps, alkyl aryl sulfonates, olefin sulfonates, (linear alkane) sulfonates, hydroxy-alkane sulfonates, long chain alcohol sulfates and OXO, sulfated glycerides, sulfated ethers, sulfo-succinates, alkanesulfonates, phosphate esters, sucrose esters, and anioinic fluoro-surfactants; Representative classes of cationic surfactants include quaternary ammonium or quaternary pyridinium salts containing at least one hydrophobic alkyl or aralkyl group, representative classes of non-ionic surfactants include condensates of a long chain alkanol with poly (oxides of ethylene) or with phenols, or condensates of long chain carboxylic acids or amines or amides with polyethylene oxide, and related compounds, wherein the long chain moiety is condensed with an aliphatic polyol such as sorbitol or condensation products of ethylene propylene oxides or fatty acid alkanolamides and fatty acid amine oxides; Representative classes of amphoteric / zwitterionic surfactants include7

ES 2 175 387 T3 and in sulfonium and phosphonium surfactants, optionally substituted with an anionic solubilizing group. The surfactant ratio, expressed as a fraction of all surfactants present, is often 2/10 to 8/10 for anionic, 0 to 6/10 for nonionic, and 0 to 3/10 for the other surfactants. .

The zeolite need not comprise the entire content of the composition improver, and indeed in some respects it need not be present at all. Such non-zeolite builders can be present in the conventional range for builders, ie about 6 to 60%. However, it is essential that according to the present invention, the sodium percarbonate is selected by virtue of passing the two screening tests, namely the specified moisture absorption and particle size distribution. Other detergent builders that are suitable for inclusion in compositions according to the present invention specifically include the aforementioned layered silicates, alkali metal phosphates, particularly tripolyphosphate but also tetrapyrophosphate and hexametaphosphate, especially the sodium salt of each, metal. alkaline, preferably sodium carbonate, alkali metal and alkali metal silicates, preferably sodium borates. Still another class of builders that can be incorporated comprise organic chelating builders such as aminopolycarboxylates and aminopolymethylene phosphonates or hydroxyphosphonates, including nitrilotriacetate or trimethylene phosphonate, ethylenediamine tetraacetate or tetramethylene phosphonate, diethylene triamine pentamethylene phosphonate, diethylene triamine-1,2-phosphonate or cyclo-diathylene-tetraphosphonate. usually fully or partially in the form of the sodium salt. Chelating carboxylate builders comprise monoomeric and oligoomeric carboxylates, including glycolic acid and ether derivatives, salts and derivatives of succonic and tartaric acid, citrates, carboxy-derivatives of succinates, and polyaspartates. Others include ethane- or propane-tetracarboxylates and various sulfosuccinates. Such chelating builders can be used in a relatively small amount as an enhancement of the peroxygen builder and stabilizer, such as 1 to 10%. Additional builders, including chelating builders, may be present in amounts at the discretion of the manufacturer of the composition, and in total, represent up to no more than about 40% by weight, and in many cases from about 5 to about 20% by weight. .

Additional and optional constituents of the detergent composition may include antiredeposition and soil suspension agents, bleach activators, optical brightening agents, soil release agents, foam controllers, enzymes, fabric softening agents, perfumes, colorants. and processing assistants. In total the optional constituents often comprise up to about 20% by weight of the composition, and often up to 10% by weight, excluding processing aids which may additionally constitute, if appropriate, from 0 to 30% by weight of the composition.

Antiredeposition / soil suspension agents are often selected from methyl, carboxymethyl or hydroxyethyl derivatives of cellulose, or polyvinylpyrrolidones and polycarboxylic acid polyomers such as copolymers of maleic anhydride with methacrylic acid, ethylene or methyl vinyl. Ether. At least 0.5%, and often 1 to 5% of such agent is suitably present.

The bleach activators that can normally be included are O-acyl or N-acyl compounds, which generate peroxy acid upon reaction with sodium percarbonate. Suitable classes of activators include activators a1 to a20 described in EP-A-0556017. Activators of particular or interest include TAED, SNOBS and their isononoyl analog, TAGU, and sugar osters. Such activators, when used, are typically used in an equivalent molar ratio to percarbonate of 2: 1 to 1:10, and often about 1: 1 or 1: 5 to 1: 8. In many cases this may correspond to a content between 1 and 8%, and especially 2 to 6% by weight of the composition. The user can also contemplate the incorporation of one of the manganese, cobalt or titanium complexes, also called accelerators, according to the published literature, optionally with a calcium promoter.

Ooptic brightening agents are often selected from suitably substituted aminostilbenes and especially from triazinaminostilbenes.

Soil release agents are often selected from copolymers of terephthalic acid and poly (ethylene oxide) and / or poly (propylene oxide).

Foam suppressants are often silicones or alkylated silicone materials or finely divided aerogels or solid xerogels.

Enzymes can be selected from amylases, neutral or alkaline proteases, lipases, esterases, and

ES 2 175 387 T3 cellulases that are commercially available.

Fabric softening agents include smectite clay and water insoluble tertiary amines, often in conjunction with long chain quaternary ammonium salts and / or high molecular weight polyethylene oxides. The total content of such agents is often selected from the range of 5 to 15% by weight, with the organic component providing about 0.1 to 2% by weight.

Processing aids are often selected from sodium and / or magnesium sulfate. In concentrated or ultra-concentrated compositions, they often make up a relatively small proportion of up to about 5%, but in traditional powders, they can often make up 20 to 40% of the weight of the composition.

The detergent compositions of the present invention are often prepared by dry mixing the particulate sodium percarbonate, and sometimes a fraction of the zeolite, with a pre-formed mixture of the remaining constituents. The mixture of the non-percarbonate / zeolite constituents can be obtained in a conventional manner by spray drying a paste of these constituents to form a particulate mixture, or by agglomeration.

It would also be recognized that the benefit of selecting sodium percarbonate by the two trials for incorporation into improved detergent compositions can equally be applied to other improved compositions containing the same builders, such as for example bleach additive compositions, which normally contain at least 5% of each of the builders and percarbonate in a weight ratio often 5: 1 to 1: 5.

Detergent compositions are prepared on a bulk scale, therefore their constituents such as sodium percarbonate, in practice must be stored in bulk and transported to the bulk detergent storage / manufacturing site. It is very convenient to use in detergent compositions such as those described above, sodium percarbonate that has been prepared in a crystallizer or crystallizer-classifier without adding a chloride, or in many cases particularly without any saline reactive agent, but which produces or can be classified to produce particulate product having the convenient size range and particle distribution indicated above. It is especially desirable to select such products that have a very low heat emission rate. A representative figure that allows a realistic comparison between products prepared using different procedures and at different sites can be obtained by first subjecting the percarbonate sample to a 7 day aging procedure in a sealed ampoule in a chamber at a constant temperature maintained at 40^°C, then bringing the percarbonate to a substantially constant value for the heat emission. Such aging is indicated herein by reference to the product that is 7 days old. The product is then transferred to a microcalorimeter, model LKB 2277, also called a thermal activity controller, which is marketed by Thermometric Limited, Sweden. The heat that is emitted by the sample is measured in a standard period, which here is 16 hours, and at a standard test temperature, which is here 40^°C. By comparison, a typical product obtained from a humid process involving the reagent saline chloride, can often emit 5 to 7 μW / g in the 16 hour test period, whereas the products of the process of the invention, they typically emit less than 3 μW / g, often at least 0.5 μW / g, and in many cases 1 to 2 μW / g. The products of the invention that have lower thermal emission can allow sodium percarbonate to be handled and stored in very adverse conditions, such as in areas with hot climates or with fewer facilities in precautionary means to eliminate heat.

It is beneficial in practice to select for incorporating into detergent compositions PCS product that not only has a large particle size, preferably with a narrow path below 1, and an HA (moisture absorption) below 30 g / 1000 g, otherwise it has a 7-day aging LKB below 3 μW / g.

Having described the invention in general terms, its specific embodiments are described in greater detail by way of example only.

In these Examples and Comparisons, moisture absorption and particle size distribution were measured and used as the basis for selecting sodium percarbonate. The data shown for moisture absorption were obtained by testing at 80% relative humidity and at 32^°C previously described here.

The sodium percarbonate used respectively in Examples 1-3 was obtained by sieving a sample

ES 2 175 387 T3 of sodium percarbonate produced by Solvay Interox and which had a low moisture absorption, by a set of sieves having the mesh sizes indicated below, in three fractions. Similarly the sodium percarbonate used in Comparisons R1 to R3 was obtained by sieving a differently produced sodium percarbonate that had much higher moisture absorption, through the same set of sieves to produce three fractions. The mean particle sizes of the three corresponding fraction pairs, 1 and R1, 2 and R2, and 3 and R3, were similar.

The sodium percarbonate of Examples 1-3 was obtained by a crystallization method in which a saturated or nearly saturated sodium percarbonate bulk aqueous solution was obtained by first reacting hydrogen peroxide and sodium carbonate in solution, and then introducing an agent Saline reagent without chloride, sodium sulfate, in order to promote the crystallization and precipitation of sodium percarbonate. The crystallization process was carried out in an integrated apparatus comprising a crystallizer positioned above and attached to a classifier. The liquid flowed up through the classifier and crystallizer, and a fraction was recycled to the base of the classifier. The saline sodium sulfate reagent reduced the solubility of the sodium percarbonate solution introduced into the crystallizer, producing some nucleation and also deposition of the percarbonate on the percarbonate particles present in the crystallizer. As the particles grew in the crystallizer they tended to fall under the influence of gravity in the classifier below. A product mainly comprising particles of at least 400 µm in diameter was extracted from a lower zone of the crystallizer. By virtue of the tendency for sodium percarbonate particles to exit the crystallizer as they increased in size, rather than staying in it to increase in size, the resulting product tended to have a narrower particle size distribution than that of the crystallizer. product of a conventional "huomeric" crystallization process to prepare sodium percarbonate. Thus, although the unscreened product had a mean particle size in the range of 600 to 650 µm, there were relatively few particles above 800 µm in diameter. The product was dried with hot air.

In the comparison compositions, sodium percarbonate was obtained by a commercial "huomer" manufacturing route from Solvay Interox, in which sodium percarbonate was reacted in solution with hydrogen peroxide to form a concentrated percarbonate solution. sodium chloride, in the presence of sodium chloride as a saline reactive agent in solution, and the mixture was cooled, resulting in the formation of crystalline percarbonate. Likewise, the comparison product was dried with hot air.

In the Examples and Comparisons, the detergent composition was obtained by dry mixing 10% by weight / weight of sodium percarbonate with 90% by weight of a base detergent composition containing zeolite A (Na) in an amount of about 30% by weight / weight. weight.

Samples (50 g) of the mixed composition were transferred to polyethylene lined cardboard boxes that were hermetically sealed, and the cardboard boxes were stored in a temperature and humidity controlled cabinet at 26.7 ° C, 80% humidity. relative, for 6 weeks. The available oxygen content (DOC) of the composition was measured at the beginning and at the end of the storage period, using a standard titration method with potassium permanganate, and the remaining DOC at the end was expressed as a percentage of its initial value.

TABLE 1

<td>Ex / Comp.</td><td>Particle size μm</td><td>Moisture absorption (g / kg)</td><td>% COD recovery</td>

<td> 1</td><td> 600-850</td><td> 10</td><td> 50</td>

<td> 2</td><td> 425-600</td><td> 10</td><td> 32</td>

<td> 3</td><td> 250-425</td><td> 10</td><td> 19</td>

<td>C1</td><td> 600-850</td><td> 100</td><td> 38</td>

<td>C2</td><td> 425-600</td><td> 100</td><td> 16</td>

<td>C3</td><td> 250-425</td><td> 120</td><td> 0</td>

IS 2 175 387 T3

From the Table it can be seen that the sodium percarbonate used which intrinsically has a mean particle size of about 500 or higher, combined with low moisture absorption, had a stability in the presence of zeolite builder that was significantly and perceptibly greater than if only one of the two parameters had been selected. In particular, it was observed that the stability of percarbonate having a very similar particle size range / distribution differs remarkably, despite the fact that from the description of the products of EP451893 of the same particle size range (which does not have been coated to modify stability) would be expected to be very similar; for example the product in Ex2 was twice as stable as the product in C2. The improvement in DOC retention using percarbonate having low moisture absorption compared to high, was systematically about 14 to 18% in the test. This can be seen by comparing samples with the same particle size fraction, for example Ej2 with C2, and likewise, the improvement of selecting larger particles is maintained in the range of 14 to 18% as can be seen by comparing the results with those of the Respective examples Ej1, Ej2 and Ej3.

The results clearly demonstrate that the process of selecting sodium percarbonate based on the double measurement of moisture absorption and particle size represents a practical method for selecting sodium percarbonate that is intrinsically suitable for incorporation into detergent compositions, that is, the selection of the materials in Examples 1 and 2.

In another series of tests, a sodium percarbonate sample of the same type as that used before sieving in Examples 1 to 3 and having a moisture absorption of 10 g / 1000 g in the relevant test, was contacted with materials. in fine particles contemplated as coating agents. It was found that the effect of putting it in contact with sodium carbonate, sodium sulfate and sodium silicate, even at 5% of the material did not increase the relevant determining stability (moisture absorption) to more than approximately 15 g / 1000 g, but that the presence from 5% sodium chloride I increased the moisture absorption to approximately 100 g / 1000 g, confirming that it is very important to prevent the presence of an excess of chloride to retain the benefit of the inherent stability of the selected percarbonate of the invention, in a subsequent coating operation.

In another demonstration, the COD stability of sodium percarbonate samples was measured in a mixture in particles with a detergent composition containing a zeolite A (Na salt) in particles, and a laminar silicate (SKS-6) as builders, taking Carry out the test in wax-laminated boxes at 32 ° C and 60% relative humidity. In test 4, the sodium percarbonate had been produced by a method essentially like the one that produced the products used in Examples 1-3, that is, an integral crystallizer / classifier, using sodium sulfate saline reagent, but with the conditions controlled to produce a product having an average particle size of approximately 750 µm and a moisture absorption &lt;10 g / 1000 g. In Test 5, another sample of sodium percarbonate used in Test 4 was coated with a 50/50 weight / weight mixture of sodium carbonate and sodium sulfate, wetting the particulate percarbonate with a concentrated aqueous solution of the coating agents in on a laboratory scale, stirred in the mixer at about 25-30 ° C to provide a total dry weight of 3% coating agents, and drying the wet percarbonate in a fluid bed drier.

In test C6 (comparative), the sodium percarbonate used was obtained by taking a conventional "wet bed" product manufactured using a chloride saline reagent (moisture absorption approximately 100 g / 1000 g) and coating the particulate material of the same form as the product for test 5 with a 50/50 weight / weight mixture of sodium carbonate and sodium sulfate (total 3% dry weight of coating), the resulting material has an average particle size of approximately 720 µm. The COD recovered after 6 weeks of storage for the test products was respectively

<td>Essay 4</td><td> 43%</td>

<td>Essay 5</td><td> 65%</td>

<td>Test C6</td><td> 32%</td>

From the above data, it can be seen that in the presence of the zeolite / lamellar silicate, the uncoated percarbonate of test 4 was more stable than the coated product of test C6 in a significant amount, confirming that by meeting an adequate combination of parameters According to the present invention, a product with better stability in relation to the percarbonate obtained conventionally can be obtained, even with a similar particle size, after coating. Second, it can be seen that the percarbonate from Test 4 was a particularly suitable base for a coating.

ES 2 175 387 T3 later, as the coating also further enhances the stability of the percarbonate. Although the coating level was the same in tests 5 and 6, the stability of the coated product that meets the criteria for particle size and moisture absorption of the compositions of the invention, was twice as good as the coated product. comparison.

Example 7 and Comparison 8

In this Example, particle size and moisture absorption tests were carried out on two samples of sodium percarbonate that had been produced by reaction between a concentrated solution of hydrogen peroxide and bulk sodium carbonate, and precipitation of bone in the presence of of a low concentration of diphosphonic acid stabilizer, and sodium silicate, polyacrylate, and modifiers of the crystalline pyrophosphate, but in the absence of a saline reactive agent.

The moisture absorption test was carried out in the same way as previously described here, and produced results of 14.1 and 10.7 g / kg in 24 hours of storage, demonstrating that it was within the acceptable range below 30 g. / kg. The particle size distribution was obtained by sieving through a set of standard sieves, and this showed that the mean particle size was respectively 723 and 747 µm, and that less than 7% of the particles were below 425 µm. This product passes the selection procedure.

For comparison , at C8 the same tests were carried out on a commercially available standard sodium percarbonate sample obtained using a standard saline reagent procedure. This comparison absorbed 122 g / kg of moisture in 24 hours and had an average particle size of 465 µm. This sample did not pass the screening procedure.

Then other samples of the Example and comparison products were mixed with the reference detergent A in a weight ratio of 15%: 85%, and stored in boxes lined with polyethylene in a constant temperature room maintained at 32 ° C and 80 ° C. % relative humidity. The active oxygen content of the compositions was periodically measured by the standard titration method, and compared with the initial measurement to determine the proportion of active oxygen that had been retained.

Detergent A contained approximately 7.5% (linear alkyl) benzene sulfonate, 25% zeolite A, 4% alcohol ethoxylate, 3% soap, 5% SIK foam inhibitor, 9% sodium carbonate. , 5% sodium sulfate, and a series of detergent additives including proteolytic enzyme, soil redeposition agent, and optical brightener, in minor amounts.

TABLE 2

<td></td><td>COD retained after 6 weeks</td>

<td></td><td>Detergent A</td>

<td>Example 7</td><td> 66</td>

<td>Comparison 8</td><td> 18</td>

From Table 2, it can be seen that the sodium percarbonate selected according to the two tests, demonstrated a significantly higher stability.

Other tests on detergent compositions containing zeolites, containing a bleach activator, tetraacetyl-ethylenediamine (3%), confirmed that the sodium percarbonate selected according to the two tests retained its DOC longer than the sodium percarbonate, which did not satisfy both. essays.

Example 9 and Comparison 10

In this Example, another sample of sodium percarbonate was tested that had been produced by the same general method as for Example 7. In the moisture absorption test, it absorbed 7.6g / kg for 24 hours. The particle size was measured as for Example 7, and showed a mean particle size of 716 µm, and 10% below 425 µm. Therefore, this sample passed both tests.

IS 2 175 387 T3

Its stability in a detergent composition B was tested against another sample of sodium percarbonate described in Comparison 8, in a mixture of 20% sodium percarbonate to 80% base detergent, in the same way as for Example 7.

Base detergent B contained approximately 8% (linear alkyl) benzene sulfonate, 3% ethoxylated tallow alcohol, 3% soap, 44% sodium tripolyphosphate, 7% sodium silicate, 20% sodium sulfate, and agent. antiredeposition of dirt and chelating agent in minor quantities.

TABLE 3

<td></td><td>COD retained after 6 weeks</td>

<td></td><td>Detergent B</td>

<td>Example 9</td><td> 72</td>

<td>Comparison 10</td><td> 62</td>

From Table 3, it can be seen that the benefit of selecting sodium percarbonate that inherently passes both tests is also evident in compositions that are enhanced with a phosphate builder, although the difference is not as great as for compositions enhanced with zeolite. .

Another sample of sodium percarbonate described in Example 9 was coated with 3% by weight of sodium carbonate / sodium sulfate (but with a 2: 1 weight ratio) in the manner described for Example 5. The stability of the COD of the resulting product in the reference detergent A, under the same conditions as for Example 7. It will be found that after 6 weeks of storage, 70% of the DOC had been retained, indicating that the coating had further improved the storage quality of the sodium percarbonate core that had intrinsically passed both tests. Examples 11 to 13

In these Examples, washing compositions are obtained by dry mixing sodium percarbonate obtained by working with a crystallization process in which sodium percarbonate precipitates from a solution containing hydrogen peroxide and sodium carbonate in a molar ratio of 0.85: 1, and in which no additional saline reagent had been introduced, the product having thermal emission properties after 7 days of aging (LKB) of &lt;3 μW / g in 16 hours, water absorption (HA) of 10 g / 1000g, tmp (mean particle size) of 770 μm (path 1.0), apparent density (DA) 920 g / 1000 g in a previously formed mixture of the other constituents. The constituents and their respective proportions are summarized in the following Table 4.

In Table 4, ABS denotes alkyl benzene sulfonate, AEO ethoxylated alcohol, other surfactants include a soap, and / or a cationic surfactant, the bleach activator is tetraacetyl ethylenediamine, or sodium nonanoyl or acetyloxybenzenesulfonate, and adjuvants. detergent include one or more complexing polycarboxylate or polyphosphonate builders, one or more cellulose derivatives, PVP and / or maleic anhydride copolymers that act as soil anti-redeposition agents, an amino stilbene optical brightener, colorant and perfume and optionally an enzyme amylase, protease, lipase, esterase or cellulase.

IS 2 175 387 T3

TABLE 4

<td rowspan="2">Example no.</td><td> 11</td><td> 12</td><td> 13</td>

<td colspan="3">Amount% by weight / weight</td>

<td>An ^ mco surfactant - ABS</td><td> 9</td><td> 15</td><td> 7</td>

<td>Non-ionic surfactant - AEO</td><td> 4</td><td> 3</td><td> 3</td>

<td>Other surfactant</td><td> 9</td><td></td><td> 3</td>

<td>Zeolite 4A</td><td> 28</td><td> 20</td><td></td>

<td>Na tripolyphosphate</td><td></td><td></td><td> 37</td>

<td>Na carbonate</td><td> 10</td><td> 14</td><td></td>

<td>Sodium percarbonate</td><td> 15</td><td> 20</td><td> 15</td>

<td>Bleach activator</td><td></td><td> 3</td><td></td>

<td>Sodium sulfate</td><td> 6</td><td> 18</td><td> 17</td>

<td>Detergent adjuvants</td><td> 9</td><td> 3</td><td> 8</td>

Similar compositions can be obtained by varying the amounts of the above listed constituents, within ranges known in the detergent industry to remain effective, and substituting all or part of the individual constituents, such as substituting all or a fraction of the ABS for an alkyl sulfate, alcohol sulfate, glyceride sulfate or succinate or phosphate esters, and / or substituting the AEO at least in part by an ethoxylated alkylphenol, a copolymer of PEO / PPO or fatty acid / amide-polyols and / or substituting zeolite 4A for SKS6, or zeolites MAP and / or partially with sodium silicate, and / or substituting at least partially tripolyphosphate for sodium tetraphosphate and / or substituting the sodium sulfate diluent for sodium chloride.

The sodium percarbonate incorporated in the compositions of each of Examples 11 to 13 respectively, can be varied using the following percarbonate products (P1 and P2) that were obtained in a crystallizer working without saline reactive agent, and that intrinsically meet the parameters of low heat emission, low moisture absorption and acceptable average particle size.

TABLE 5

<td>Product ref.</td><td>P1</td><td>P2</td><td>Q3</td>

<td>AH g / 1000 g</td><td> 14</td><td> 1,5</td><td> 9,4</td>

<td>LKB μW / g</td><td> 1</td><td> 2</td><td> 2,3</td>

<td>TMP μm</td><td> 680</td><td> 650</td><td> 950</td>

<td>route</td><td> 1,0</td><td>not measured</td><td> 0,9</td>

<td>DA g / 1000 g</td><td> 880</td><td>not measured</td><td> 900</td>

<td>COD%</td><td> 14,7</td><td> 14,9</td><td> 15,0</td>

IS 2 175 387 T3

Other examples of PCS (P4 to P7) that can be used instead of the P2 or P3 products include products prepared in the same apparatus under varied working conditions, still avoiding the addition of a saline reactive agent, and whose AH is acceptable ( &lt;30 g / 1000 g) and low LKB at 7 days of aging of &lt;3μ W / g at 16 hours, and other phasic characteristics are listed below

TABLE 6

<td>Product ref.</td><td>Q4</td><td>P5</td><td>Q6</td><td>Q7</td>

<td>TMP μm</td><td> 680</td><td> 770</td><td> 840</td><td> 700</td>

<td>route</td><td> 1,1</td><td> 1,2</td><td> 1,0</td><td> 1,2</td>

<td>DA g / 1000 g</td><td> 930</td><td> 920</td><td> 920</td><td> 860</td>

<td>COD%</td><td> 15,0</td><td> 14,8</td><td> 15,0</td><td> 14,4</td>

The PCS can be further varied using products that are inherently acceptable as a core for a coating, for example, in an amount of 2 to 5% w / w (particularly 3%) sodium sulfate / carbonate, borate / sodium silicate, or coating agents in contact in acid form such as a mixture of baric acid with neutral salts such as sodium sulfate and / or chloride, and optionally a carboxylic acid and / or hydroxycarboxylic acid capable of forming a complex with an oxy-boron compound, or especially using mother liquors containing added sodium sulfate in a molar ratio of Na2 C O3: Na2S O4 from 1: 2 to 2 :1.

The compositions will demonstrate different rates of decomposition of sodium percarbonate, but all will have the benefit of using the easily storable PCS in bulk and the stability offered by a large particle size compared to the use of PCS that do not comply with either or both. characteristics of low thermal emission and large particle size.