IE53182B1 - Bleaching activator granules,their preparation and their use in detergent and bleaching compositions - Google Patents

Abstract

1. Claims for the Contracting states : BE, CH, DE, FR, GB, IT, LI, LU, NL, SE Bleaching activator in granular form comprising tetraacetylethylenediamine and a coating agent comprising at least one alkali metal polyphosphate and an alkali metal derivative of cellulose, characterised in that it is composed of : - 55 to 90% by weight of tetraacetylethylenediamine and - 10 to 45% by weight of coating agent. 1. Claims for the Contracting State : AT Process for washing articles based on natural, synthetic or artificial fibres, characterised in that there is used a bleaching activator in granular form, comprising tetraacetylethylenediamine and a coating agent comprising at least one alkali metal polyphosphate and an alkali metal derivative of cellulose, and composed of : - 55 to 90% by weight of tetraacetylethylenediamine and - 10 to 45% by weight of coating agent.

Description

The present invention relates to granules of coated bleaching activator, to a process for coating and granulating the said activator, and to the use of resulting granules in or with detergent and bleaching compositions. Textile materials may be washed and bleached by means of a washing and bleaching bath using the granules of the invention.

More precisely, the present invention relates to granules of coated Ν,Ν,Ν1,Ν'-tetraacetylethylenediamine, their preparation and their use in detergency.

In the following description of the present invention: tetraacetylethylenediamine is to be understood as meaning: Ν,Ν,Ν',Ν'-tetraacetylethylenediamine; per-compound is to be understood as meaning: a salt which releases hydrogen peroxide in aqueous solution, as is the case, for example, of alkali metal perborates, percarbonates, persilicates and pexphosphates; detergent composition, also called detergent, is to be understood as meaning: a solid product containing at least one organic surface-active agent, at least one per-compound and at least one builder, which is a detergency adjuvant, one of the functions of which is to sequester the ions responsible for hardness in water; textile materials are to be understood as meaning: either natural, artificial and/or synthetic fibres or the products manufactured therefrom; and particle size is to be understood as meaning: the average diameter of the particles. The average diameter is defined as being a diameter such that 50% by weight of . the particles have a diameter which is more or less than the average diameter.

The conventional detergent compositions used for washing textile materials comprise a surface-active agent (anionic, non-ionic, cationic or amphoteric), a builder and a bleaching per-compound.

It is well known that per-compounds, and in particular perhydrates, release, in an aqueous medium under certain conditions, an amount of hydrogen peroxide which, by virtue of its oxidising power, makes it possible to remove certain coloured stains.

The per-compounds used in detergent compositions generally only have sufficient oxidising activity at temperatures above 60°C.

To enhance the bleaching effect of the detergent or bleaching composition at lower temperatures, it has been recommended to add an organic activator for the per-compound to the composition. The activator reacts with the hydrogen peroxide released by the per-compound to form, in the detergent medium, a bleaching agent which is active at lower temperatures, for example at between 20 and 60°C.

Amongst the known organic activators, tetraacetylethylenediamine has proved particularly effective.

Unfortunately, this activator presents problems of storage stability when it is incorporated in the detergent compositions. When in contact with the other constituents of the detergent composition, namely alkaline substances, the per-compound and hydrated compounds, the activator tends to hydrolyse and .to perhydrolyse. This partial decomposition results in the appearance of pungent odours and colouration, and also in a reduction of its bleaching power.

To overcome these disadvantages, attempts have been made to protect the tetraacetylethylenediamine with the aid of a coating so as to isolate it from the other constituents capable of causing its degradation.

The choice of coating agent is governed by a number of essential requirements, namely: it must be solid at ambient temperature and must therefore have a melting point above 40°C; it must be inert towards the activator and the usual components of the detergent compositions; it must be soluble or dispersible in the washing bath; it must facilitate the solubilisation of the tetraacetylethylenediamine and not delay its dissolution at all; it must not reduce the detergent power and bleaching power of the washing baths; it preferably has a particular detergency activity and, consequently, it preferably already exists in the detergent compositions; and it is preferably inexpensive.

In addition to these various conditions which the coating agent must satisfy, it should be noted that the nature of the coating agent influences the characteristics of the granules to be obtained. Consequently, the choice of the coating agent must also take account of the properties required of the granules, which are as follows: the granules obtained must release the crystals of tetraacetylethylenediamine from the start of the washing cycle, to form peracetic acid ions as rapidly as possible in the detergent bath; the granules must possess a good binder and must have adequate mechanical properties so as not to disintegrate prematurely during the manufacture of the detergent composition or during its handling, in particular during its packaging or transportation; and finally, the granules must have a composition such that the amount of coating agent introduced into the detergent composition does not cause an imbalance in its formulation, thus leading to undesired side-effects such as, for example, redeposition or poor foam control.

There is therefore also a difficulty to be overcome as regards the composition of the granules to be obtained, which implies, on the one hand, a minimum amount of coating agent so as not to cause an imbalance in the detergent composition, and, on the other hand, a maximum amount of coating agent so as to enhance the binding effect and the mechanical properties and so as to obtain effective protection of the tetraacetylethylenediamine.

There is also a difficulty to be overcome as regards the manufacture of granules containing a high proportion of tetraacetylethylenediamine. In fact, the latter does not possess any property of self-agglomeration11 and it is necessary to use a coating agent having binding properties, and the problem of the granulation of the tetraacetylethylenediamine will be the more difficult to solve, the smaller the amount of the coating agent.

From the foregoing, it will be apparent that it is difficult to choose a coating agent so as to obtain good protection of the tetraacetylethylenediamine during storage, in order to preserve its bleaching activity to the maximum extent.

It has been proposed for some time to use different types of coating for the tetraacetylethylenediamine.

Thus, French Patent 2 281 160 describes, as coating substances, long-chain fatty acids such as myristic acid, stearic acid, hydrogenated tallow fatty acids, acid waxes or oxidised paraffin waxes. The disadvantage of using 53162 η these organic substances is that the granules obtained are frequently awkward to handle because of the physical nature of the binder. Moreover, a delay in the formation of the peracetic acid ions is observed.

French Patent 2 109 941 describes granular compositions containing from 5 to 50% by weight of the bleaching activator, tetraacetylglycolurile, and from 95 to 50% by weight of a coating substance comprising sodium triphosphate. As the amount of binder used is large, it is not possible to obtain granules containing a high concentration of activator.

The present invention proposes to provide granules of coated tetraacetylethylenediamine which, to a very large extent, satisfy all the conditions listed above and avoid the above-mentioned disadvantages.

The bleaching activator granules of the present invention comprise from 55 to 90% by weight of tetraacetylethylene-diamine; and from 10 to 45% by weight of a coating agent comprising an alkali metal polyphosphate and an alkali metal cellulose derivative.

Protection of the tetraacetylethylenediamine in the form of the granules of the invention makes it possible to eliminate the degradation of the tetraacetylethylenediamine during storage and does not in any way impair the activating properties of the tetraacetylethylenediamine on the per-compounds. it JOSZ Furthermore, it has been found, unexpectedly, that the rate of dissolution of the granulated and coated tetraacetylethylenediamine according to the invention is greater than the rate of dissolution of tetraacetylethyl5 enediamine by itself. The practical value of the invention is therefore that the peracetic acid ions are formed very rapidly in the detergent medium.

Finally, it has been observed that the incorporation of the tetraacetylethylenediamine into the detergent compositions can be facilitated because of the possibility of dry-mixing the granules of the invention with the other constituents of the detergent composition.

The present invention also provides a process for the preparation of the said bleaching granules, characterised in that a pulverulent mixture of the tetraacetylethylenediamine and the alkali metal polyphosphate is prepared, and in that a solution of an alkali metal cellulose derivative is sprayed onto the moving bed thus formed.

It is to be understood that the term solution, as used herein, designated either a solution or a dispersion of the cellulose derivative.

The nature and the characteristics of the components forming part of the granules of the invention will now be described.

The tetraacetylethylenediamine to be treated is in the form of particles generally having a size of 0.02 to 0.25 mm and preferably 0.05 to 0.15 mm. The tetraacetylethylenediamine used preferably has the abovementioned particle size, because if the particles are too small, undesirable dusts are formed, and if the particles are too large, there are likely to be problems on agglomeration, and, during use in detergency, the dissolution of the tetraacetylethylenediamine will be retarded. The particle size of the tetraacetylethylenediamine can be determined by any usual method, for example by dry sieving, by sedimentation or by direct counting of the particles with the aid of a COULTER-COUNTER instrument, which is based on recording conductimetric perturbations which accompany the passage of the particles through a diaphragm of given size.

The alkali metal polyphosphate is preferably a sodium polyphosphate. Sodium pyrophosphate, sodium hydrogen pyrophosphate and sodium triphosphate are suitable. These salts are preferably used in anhydrous form.

Sodium triphosphate is preferably chosen. It can be used in its commercial form, which contains metals such as iron, copper and nickel as impurities; in general, the amount of metal ions does not exceed 200 ppm. It is preferred to use sodium triphosphate having a reduced proportion of metal impurities, for example a proportion of 20 to 100 ppm.

As regards the particle size of the sodium triphosphate, which can be determined in the same way as that of the tetraacetylethylenediamine, it is suitably 0.02 to 0.08 mm, which corresponds to the sodium triphosphate commonly used in detergency.

The second component forming part of the coating agent is organic in nature, since it is a cellulose derivative. Carboxymethylcellulose, methylcellulose and hydroxyethylcellulose may be mentioned in this respect.

These cellulose derivatives are preferably used in the form of their sodium salt.

Sodium carboxymethylcellulose constitutes a preferred starting material. No precise particle size characteristic is required, because it is used in the form of an aqueous solution. According to the invention, the sodium carboxymethylcellulose commonly used in detergency can be employed.

It usually has a degree of substitution varying from 0.5 to 0.7, the degree of substitution expressing the average number of carboxyl radicals fixed to each unit of the cellulose chain. As regards its degree of polymerisation, which represents the length of the cellulose chain and determines the viscosity, it can be determined so as to obtain a solution having the desired viscosity, as specified below.

The various conponents defined above should be used in amounts such that the_bleaching granules obtained have the following composition: from 55 to 90% by weight of tetraacetylethylenediamine ; and from 10 to 45% by weight of the coating agent.

The proportions of the preferred coating agent comprising sodium triphosphate and sodium carboxymethylcellulose will now be.defined, but it is self-evident that the values given are also appropriate for another polyphosphate or another cellulose derivative.

The amount of sodium carboxymethylcellulose used in the coating agent, expressed as the weight ratio (sodium carboxymethylcellulose/tetraacetylethylenediamine), can vary within a range, the limits of which should be fixed in the following way: the lower limit can be determined so that the granules obtained possess the required mechanical strength properties, and the upper limit should be defined as a function of at least two parameters to be observed, namely, on the one hand, a physico-chemical parameter which makes it necessary to exclude excess sodium carboxymethylcellulose, which would be likely to delay the release of the tetraacetylethylenediamine and the formation of the peracetic acid ions, and, on the other hand, a process constraint relating to the manufacture of the granules, which would necessitate the use of a larger amount of water at that stage, and this would have to be removed by drying and would hinder the granulation or even make it impossible. The amount of sodium carboxymethylcellulose is desirably chosen so that the said ratio varies from 1/100 to 1/10, preferably from 1/30 to 1/15.

The amount of sodium triphosphate used, expressed as the weight ratio (sodium triphosphate/tetraacetylethyl5 enediamine), is not critical and can vary within wide limits. However, it is a function of the amounts of tetraacetylethylenediamine and sodium carboxymethylcellulose and will therefore generally be fixed so that its weight ratio to the tetraacetylethylenediamine varies from 1/10 to 4.04/5, preferably from 1/4 to 2/3.

The preferred composition of the granules of the invention are given below by way of examples (the percentages are expressed as the weight of solids): from 60 to 75% by weight of tetraacetylethylene15 diamine; from 20 to 40% by weight of sodium triphosphate; and from 2 to 4% by weight of sodium carboxymethylcellulose.

As regards the process for the preparation of the bleaching granules of the invention, it has been found that it is advantageous to carry out the coating at the same time as agglomeration, leading directly to granules suitable for addition to the detergent compositions.

The process of the invention consists in first preparing a pulverulent mixture of the tetraacetylethylenediamine and the sodium polyphosphate, converted to the 53183 desired particle size and in the appropriate ratio, and in pouring the resulting mixture onto any device making it possible to form a moving bed, onto which a solution of the cellulose derivative, in,say, the sodium form, is sprayed.

The process for the preparation of the granules of the invention is described below, sodium triphosphate and sodium carboxymethylcellulose being chosen as the coating agent, but this process can easily be adapted by those skilled in the art, when using another polyphosphate or another cellulose derivative.

According to a preferred embodiment of the invention, which makes it possible to obtain bleaching granules continuously and on an industrial scale, the procedure is as follows: Firstly, a homogeneous pulverulent mixture of tetraacetylethylenediamine and sodium triphosphate is prepared. To do this, the two abovementioned components, having the desired particle size, are first weighed and introduced into a mixer. The mixer used can be any apparatus which makes it possible to perform dry mixing without destroying the particle size. Rotating-drum mixers, Y-type rotating mixers or mixers of the mixinghopper type are suitable for this operation.

The resulting mixture is then poured into a granulating apparatus, which can be a rotating-drum granulator having a large charge in motion.

An illustration of this type of apparatus, which is preferably employed, is a coating drum with a cylindrical bowl, equipped with devices for introducing and discharging the powder and also fitted with a device for spraying liquid under pressure. The coating drum has a bowl of which the inclination of the axis of rotation is preferably 43 to 45°, relative to the horizontal.

A charge consisting of the tetraacetylethylenediamine and sodium triphosphate is introduced into the coating drum, typically in an amount of 30 to 100 kg per m of coating drum, preferably 40 to 80 kg per m^ of coating drum.

The pulverulent mixture is kept in motion by virtue of the rotation of the coating drum: the speed of rotation of the coating drum is such that the tangential speed of the bowl of the coating drum is 0.5 to 3 m/second, preferably 1 to 2 m/second.

In addition, the solution of sodium carboxymethylcellulose which is to be sprayed is prepared. To do this the minimum amount of water should be used so as to avoid or minimise the drying operation. The amount of water to be used is a function of the concentration of sodium carboxymethylcellulose to be obtained, which must not be too high because this would give an excessively high viscosity, preventing any spraying. This concentration should preferably give a spraying solution with a final viscosity of less than 200 cps, this viscosity value being obtained at 50°C on a 5% strength solution, using a --------- , shear viscometer; the velocity gradient chosen for the -1 -1 measurement is 25 second to 200 second It is preferred to use a solution of sodium carboxymethylcellulose having a viscosity of 100 to 150 cps.

Generally, when using a sodium carboxymethylcellulose of detergency grade, solutions containing from 2 to 10%, preferably from 3 to 8%, by weight of sodium carboxymethylcellulose are prepared.

The spraying solution of sodium carboxymethylcellulose is prepared and kept at a temperature which is preferably 30 to 80°c, with the aid of a suitable heating device.

The solution of sodium carboxymethylcellulose is sprayed onto the pulverulent mixture by means of a spraying nozzle, under a pressure of , say, 2 to 10 bars, preferably 4 to 5 bars.

The spraying time is a function of the amount of sodium carboxymethylcellulose which it is desired to introduce into the granules.

The finished granules are removed from the bowl of the coating drum with the aid of a discharging device such as a scraper. This gives a wet powder generally having a water content of 20 to 40%, preferably 25 to 35%.

The process is advantageously carried out continuously. To do this, the coating drum is fed continuously so as to obtain an average residence time of the granules in the coating drum of 10 to 60 minutes, and the resulting granules are discharged progressively by means of a suitable discharging device.

The granules obtained are then subjected to simple sifting; this operation alone can give them the particle size desired.

Generally, so that there is no segregation of the granules during the storage of the detergents, it is desired to have a particle size distribution such that the diameter of the granules ranges from 0.4 to 2.0 mm and preferably from 0.6 to 1.2 mm.

In the process of the invention, the fine particles remain in the coating drum. On the other hand, the coarse oversized granules can be ground by any suitable apparatus and recycled into the coating drum.

By way of illustration, it may be mentioned that the sifting can be carried out by simple passage through a rotating or oblique grid of appropriate mesh size.

The coating and granulating process according to the invention .makes it possible, by virtue of the choice of the particle sizes of the pulverulent substances and by virtue of the sifting operation following the granulation, to obtain any previously defined particle size distribution.

After this operation of particle size selection, the granules can be dried in a stream of hot air, which is generally at 30 to 60°C. The drying can be carried out by any method. For example, tunnel drying can be carried out by moving the granules, deposited on a conveyor belt, in counter-current to hot air. It is also possible to dry the granules in an oven, for example an oven with a rotating hearth.

The drying apparatus should be chosen so that the granules are not disaggregated during drying.

The bleaching granules forming the subject of the invention have a generally uniform particle size and good mechanical properties and can easily be incorporated into the detergent and bleaching composition.

Generally, the bleaching granules according to the invention can be introduced into the detergent and bleaching compositions by simple dry mixing, as a post-addition to the detergeht composition dried after spraying.

In addition to their use in detergent and bleaching compositions, the granules of the invention can be added directly to the washing bath comprising a detergent and bleaching composition containing a per-compound in the case of industrial use.

The detergent compositions into which the bleaching granules can be incorporated generally comprise, in addition to the per-compound used for bleaching, at least one anionic, non-ionic, cationic or amphoteric surface-active agent and at least one builder. ί i S ϊ As examples of bleaching per-compounds which can ' be used, it is appropriate to mention, in particular, sodium perborate tetrahydrate, which is the compound most commonly employed, and also various other conventional per-compounds, such as sodium perborate monohydrate, sodium percarbonate, sodium persilicate and sodium perphosphates.

For the choice of surface-active agent, reference may be made, inter alia, to the Encyclopedia of Chemical Technology, Kirk OTHMER» Volume 19 or to the various works in the Surfactant Sciences Series, Marcel DEKKER Inc. - Volume 1 : Non-ionic Surfactants by Martin J. SCHICK; Volume 4 : Cationic Surfactants by Eric JUNGERMANN; Volume 7 : Anionic Surfactants by Warner M.

LINFIELD.

As examples of anionic surface-active agents which can be used, there may be mentioned: alkali metal soaps, such as the sodium or potassium salts of saturated or unsaturated fatty acids having from 8 to 24 carbon atoms and preferably from 14 to 20 carbon atoms, or aminocarboxylic acid derivatives, such as sodium N-laurylsarcosinate and sodium N-acylsarcosinate; alkali metal sulphonates, such as alkylsulphonates, arylsulphonates or alkylarylsulphonates, in particular the alkylbenzenesulphonates of the formula R,-C,H .SO„M,, l □ 4 o 1 in which the radical R^ is a linear or branched alkyl radical containing from 8 to 13 carbon atoms, such as a nonyl, dodecyl or tri decyl radical, and Mj represents a sodium or potassium atom, an ammonium radical, diethanolamine or triethanolamine, and alkylnaphthalenesulphonates, such as sodium nonylnaphthalenesulphoriate. Other sulphonates can be employed, such as the N-acyl-Nalkyltaurates of the formula Rg-CO-NfR^J-CHg-CHg-SOgNa, in which Rg is an alkyl radical having from 11 to 18 carbon atoms and Rg is a methyl or ethyl radical, such as sodium N-oleoyl-N-methyltaurate or sodium N-palmitoyl-N-rnethyltaurate; β-sulphoethyl esters of fatty acids, for example of 1 auric, myristic and stearic acids, and olefinesulphonates containing from 12 to 24 carbon atoms, obtained by the sulphonation, with sulphur trioxide, of a-olefines such as dodec-l-ene, tetradec-l-ene, hexadec-l-ene, octadec-l-ene, eicos-l-ene and tetracos-l-ene; sulphates and sulphated products: amongst the alkyl-sulphates corresponding to the formula RgOSOgMg, there may be mentioned those in which the radical Rg is a lauryl, cetyl or myristyl radical and Mg has the meaning given above; sulphated natural oils and fats; the disodium salt of sulphated oleic acid; sulphated polyoxyethyleneated fatty alcohols of the formula R -(0-CHo-CHo—)——OSOqM. in which the radical R. is t- t~ □ x* At an alkyl radical containing from 6 to 16 carbon atoms, such as a myristyl radical, or a linear or branched alkyl radical, such as a hexyl, octyl, decyl or dodecyl radical, n^ is the number of mols of ethylene oxide, which can vary from 1 to 4, and has the meaning given above; and sulphated polyoxyethyleneated alkylphenols of the formula R_-CcH.-(O-CH„-CH„—)—OSO„M., in which the radical Rc 6 4 2 2 n^ 3 1 5 is a linear or branched alkyl radical containing from 8 to 13 carbon atoms, such as an. octyl, nonyl or dodecyl radical, n is the number of mols of ethylene oxide units, which can vary from 1 to 6, and has the meaning given above; 1Θ primary and secondary esters of orthophosphoric acid or one of its salts, which can be represented in the case of the alkyl-phosphates by the formula (RgO)PO(OMg)g, and in the case of the dialkyl-phosphates by the formula (RgO)^O(OMg), in which formulae the radical Rg is a linear or branched alkyl radical containing from 6 to 12 carbon atoms and Mg represents a hydrogen, sodium or potassium atom. Examples of the radical Rg which may be mentioned are n-hexyl, n-octyl, n-ethylhexyl, dimethylhexyl, n-decyl, dimethyloctyl, trimethylheptyl and trimethylnonyl; and polyoxyethyleneated monoesters or diesters of orthophosphoric acid or one of its· salts, which can be represented in the case of the polyoxyethyleneated alkylphosphates by the formula and in the case of the polyoxydthyleneated di alkyl-phosphates by the formula r7-o-(ch2-ch2-o^ in which formulae the radical R? represents a linear or branched alkyl radical having from 6 to 12 carbon atoms, a phenyl radical, or an alkylphenyl radical with an alkyl chain having from 8 to 12 carbon atoms, is the number of ethylene oxide units, which can vary from 2 to 8, and M2 has the meaning given above. Examples of the radical R? which may be named are the hexyl, octyl, decyl, dodecyl and nonylphenyl radicals.

As non-ionic surface-active agents, it is possible, in general, to use compounds obtained by the condensation of an alkylene oxide with an organic compound, which can be aliphatic or alkylaromatic. Suitable non-ionic surface-active agents are: polyoxyethyleneated alkylphenols, for example the products resulting from condensation with ethylene oxide at a rate of 5 to 25 mols per mol of alkylphenol, the alkyl radical being linear or branched and containing from 6 to 12 carbon atoms. There may be mentioned, very particularly, nonylphenol condensed with about 10 to 30 mols of ethylene oxide per mol of phenol, dinonylphenol condensed with 15 mols of ethylene oxide per mol aiea of phenol, and dodecylphenol condensed with 12 mols of ethylene oxide per mol of phenol; polyoxyethyleneated aliphatic alcohols resulting from the condensation of linear or branched fatty alcohols 5 containing from 8 to 22 carbon atoms with ethylene oxide at a rate of 5 to 30 mols of ethylene oxide, for example the condensation product of about 15 mols of ethylene oxide with 1 mol of tridecanol or copra alcohol, and myristyl alcohol condensed with 10 mols of ethylene oxide; carboxylic acid amides, such as the diethanolamide of optionally polyoxyethyleneated fatty acids, such as lauric acid or the acid from coconut oil; and polyoxyethyleneated and polyoxypropyleneated alcohols: the well-known products sold under the name PLURONICS are an illustration of this type of surfaceactive agent. ' They are obtained from polypropylene glycols, which are themselves insoluble in water, or from lower aliphatic alcohols containing from 1 to 8, preferably from 3 to 6, carbon atoms, which have been condensed with propylene oxide and which are also insoluble in water.

These water-insoluble derivatives of propylene oxide are rendered soluble by reaction with ethylene oxide.

As cationic agents, it is possible to use diamines, such as those of the type R_NHC„H„NH„, in which R_ is an o c 4 Ζ o alkyl radical containing from 12 to 22 carbon atoms, for example N-(2-aminoethyl)-stearylamine and N-(2-aminoethyl)23 S3182 myristylamine; amido-amines, such as those of the type RgCONHC^H^NHg, in which Rg is an alkyl radical containing from 9 to 20 carbon atoms, for example N-(2-aminoethyl)stearylamide and N-(2-aminoethyl)-myristylamide; and quaternary ammonium compounds in which, in particular, one of the radicals fixed to the nitrogen atom is an alkyl radical having 1 to 3 carbon atoms, including alkyl radicals having 1 to 3 carbon atoms and carrying inert substituents, for example halogen, acetate or methyl10 sulphate. As representative examples of surfaceactive agents of the quaternary ammonium type, there may be mentioned: ethyldimethylstearylammonium chloride, benzyldimethylstearylammonium chloride, benzyldiethylstearylammonium chloride, trimethylstearylamrnonium chlor15 ide, trimethylcetylammonium bromide, dimethylethyldilaurylammonium chloride and dimethylpropylmyristylammonium chloride, and also the corresponding methyl-sulphates and acetates.

Finally, it is possible to use amphoteric, surface20 active agents, such as the alkyldimethylbetaines of the formula: CH„ L CHq--CH„-N -CH„-COO 32 4 2 j 2 gh3 the alkylamidopropyldimethylbetaines of the formula: CHCH--(CH--)-CO-NH-CH--CH--CH--N -CH--C00- £ 2 η4 2 2 2 | 2 CHand the alkyltrimethylsulphobetaines of the formula: CHCH+ CH2 N -CH--S0, I 2 3 CH10 in the said formulae., n^ is 9 to 16.

The various anionic, non-ionic, cationic and amphoteric surface-active agents listed above can be used by themselves or in a mixture.

Amongst the abovementioned surface-active agents, sodium alkylbenzenesulphonates, sodium stearate, fatty alcohol sulphates, the sulphates of polyoxyethyleneated fatty alcohols, polyoxyethyleneated fatty alcohols, and polyoxyethyleneated and polyoxypropyleneated fatty alcohols, are very particularly suitable and are preferably used in the detergent compositions.

The detergent compositions can also contain builders, one of the functions of which is to sequester the calcium ions and magnesium ions which may be present in the water.

As examples of adjuvant alkali metal salts which can be used for this purpose, there may be mentioned carbonates, silicates, phosphates and polyphosphates.

More precisely, sodium triphosphate, sodium pyrophosphate and potassium pyrophosphate, and sodium orthophosphate may be mentioned.

Other suitable builders are natural aluminosilicates or silicates containing, inter alia, alumina, such as bentonite or vermiculite; and synthetic zeolites of the A type.

Xt is also possible to use organic adjuvant alkali metal salts, such as: aminopolycarboxylic acids, preferably used in the form of alkali metal salts, generally in the form of sodium salts. Examples which may be mentioned are nitrilotriacetic acid,ethylenediaminetetraacetic acid and N-hydroxyethyl-ethylenediaminetriacetic acid. Diethylenetriaminepentaacetic acid and the higher homologues of the aminopolycarboxylic acids mentioned are also suitable. Of all the compounds mentioned above, it is preferred to use ethylenediaminetetraacetic acid (E.D.T.A.) and/or diethyl enetriaminepentaacetic acid (D.T.P.A.); hydroxycarboxylic acids, optionally in'the form of salts, such as citric acid, tartaric acid, gluconic acid or saccharic acid; sodium oxydiacetate; and phosphonic acids, preferably used in the form of alkali metal salts, generally in the form of sodium or potassium salts. It is possible to use the diphosphonic and polyphosphonic acids corresponding to the following formulae (i)to(V): HO X OH I I I = P-C -P = 0 ι ι i HO H OH HO X OH I I I = P-C -P = 0 I ι I HO Y OH (I) (II) Rio-N\ X OH I I - C - P = 0 I I I OH X - c — 1 z OH 1 -P = 0 1 OH 3 5 HO 0 = P- I X 1 -ΟΙ X 1 -C — 1 OH 1 P = 0 1 HO Z 2 Z OH (III) (IV) (V) in which denotes an . alkyl radical and R^ denotes an alkylene radical having from 1 to 8, and preferably 1 to 4, carbon atoms, X and Z represent a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms, and Y denotes one of the following groups: -OH, -NHg or -NXR1Q. It is also possible to use a phosphonic acid corresponding to the following formula (VI): -n - CH, I 2 H - C - H I HO - P - OH (I 0 o in which ηθ represents a number from 1 to 4. Other suitable examples of phosphonie acids are described in French Patent 2,437,442. The following phosphonie acids are preferentially chosen: amino-tri-(methylenephosphonic) acid (A.T.M.P.), ethylenediamine-tetra-(methylenephosphonic) acid (E.D.T.M.P.) and diethylenetriaminepenta-(methylenephosphonic) acid (D.T.P.M.P.).

The abovementioned builders can be used by themselves, but are preferably used in a mixture. Sodium disilicate, sodium carbonate, sodium orthophosphate, sodium pyrophosphate, sodium triphosphate and the sodium salt of nitrilotriacetic acid are preferentially chosen.

The detergent compositions generally contain, apart from the surface-active agents and the builders, a variable amount of a certain number of conventional additives. Examples of these ingredients are foamcontrol agents,' such as polysiloxanes; inorganic salts such as sodium sulphate; bleaching agents, such as hydrogen peroxide and its hydrates, peroxides and persalts, by themselves or in a mixture with bleaching precursors and other anti-redeposition agents, such as carboxymethylcellulose , carboxymethylhydroxyethylcellulose, polyvinyl alcohol, maleic acid/vinyl ether copolymers, acrylic acid, by itself or copolymerised with vinyl monomers, water-soluble sulphonated polyesters and watersoluble polyester-polyurethanes; fluorescence agents, such as stilbenes, furans and thiophenes, and also small amounts of perfume, colourants and enzymes.

The bleaching granules are typically introduced into the detergent compositions in an amount such that there is approximately from 1 to 10%, and preferably from 2 to 4%, by weight of tetraacetylethylenediamine.

The per-compound is typically added to the detergent compositions at a rate of 5 to 35%, preferably 10 to 20%. by weight.

The weight ratio of the tetraacetylethylenediamine 10 to the per-compound is suitably from 2/3 to 1/35 und preferably from 1/2 to 1/20.

The detergent compositions usually contain at least from 5 to 50% by weight of an anionic, non-ionic, cationic or amphoteric surface-active agent or a mixture thereof, and from 10 to 60% by weight of a builder. Preferably, from to 25% by weight of an anionic or non-ionic surface-active agent or a mixture thereof, and from 10 to 40% by weight of a builder, are introduced into the detergent compositions.

The following Exanples further illustrate the present invention. The percentages given are expressed by weight.

DETERGENT COMPOSITION (1) linear alkylbenzenesulphonate (the alkyl radical containing about 12 carbon atoms) 6.2 natural tallow soap 4.4 fatty alcohol containing 18 carbons and carrying 11 units of ethylene oxide 3.2 sodium triphosphate 41.3 sodium sulphate 12.7 sodium perborate 23.2 carboxymethylcellulose 0.5 water 8.5 DETERGENT COMPOSITION (2) fatty alcohol containing 14 carbons and carrying 7 units of ethylene oxide 11 sodium orthophosphate 4 sodium pyrophosphate 10 sodium triphosphate 26 sodium disilicate 8 sodium sulphate 13 sodium perborate 20 carboxymethylcellulose 0.5 foam-control agent (polymethylsiloxane) 0.5 water 7 DETERGENT COMPOSITION (3) linear alkylbenzenesulphonate (the alky] radical containing about 12 carbons) 11 soap of copra fatty acid 10 sodium triphosphate 35 sodium disilicate 5 sodium sulphate 5 sodium perborate enzyme water DETERGENT COMPOSITION (4) linear alkylbenzenesulphonate (the alkyl radical containing about 12 carbons) sodium stearate fatty alcohol containing 18 carbons and carrying 11 units of ethylene oxide sodium orthophosphate sodium pyrophosphate sodium triphosphate sodium disilicate sodium carbonate sodium sulphate sodium perborate water DETERGENT COMPOSITION (5) linear alkylbenzenesulphonate (the alkyl radical containing about 12 carbons) sodium -stearate fatty alcohol containing 18 carbons and carrying 11 units of ethylene oxide sodium orthophosphate sodium pyrophosphate sodium triphosphate sodium disilicate 13.5 1.3 3.7 0.9 .8 26.5 4.5 0.6 .2 9.2 6.7 4.8 1.1 3.4 .2 6.6 3/ sodium carbonate 1.2 sodium sulphate 14.2 sodium perborate 11.4 water 11.2 The granules of the present invention have excellent storage stability in the detergent compositions: the tetraacetylethylenediamine is effectively preserved from the other components of the detergent composition which would be likely to degrade it.

The detergent compositions containing the bleaching granules according to the invention are suitable for washing articles of all kinds, based on natural, synthetic or artificial fibres, and more particularly for washing textile materials based on natural fibres, such as cotton, j_5 optionally blended with other fibres, in particular polyester fibres.

The concentration of the bleaching granules in the washing bath, expressed as the weight of tetraacetylethylenediamine, is generally such that there is 0.05 to 1.00 g per litre of aqueous bath. The upper limit is . obviously not of a critical nature, but it is preferable to choose a concentration of 0.1 to 0.3 g/litre, because higher concentrations do not bring any significant advantage in terms of the effectiveness of the products of the invention.

The temperature of the aqueous medium which is used during washing is not critical inasmuch as the bleaching granules behave effectively at temperatures ranging from 20 to 1OO°C and preferably from 30 to 60°C.

It should be noted that the washing is preferably carried out at low temperature, because of the presence of the tetraacetylethylenediamine, all the more so because the rate of dissolution of the granules of coated tetraacetylethylenediamine of the invention is greater than the rate of dissolution of tetraacetylethylenediamine by itself, which makes it possible rapidly to obtain the peracetic acid ions and then the active oxygen making it possible to obtain the bleaching effect.

The granules illustrated below are subjected to the tests listed below, which demonstrate their physico-chemical properties and their bleaching effectiveness when they are introduced into a detergent composition, EXAMPLES 1) Preparation of granules of the invention, having the following composition by weight (the percentages are expressed as the weight of solids): 74.5% % tetraacetylethylenediamine anhydrous sodium triphosphate sodium carboxymethylcellulose 2.5% In the Examples which follow, granule;·, having the composition by weight given below are prepared, but the tetraacetylethylenediamine and sodium triphosphate used are of different particle size, the particle size of the sodium triphosphate always being substantially smaller than that of the tetraacetylethylenediamine.

The granules are prepared according to the following procedure: EXAMPLE 1 First, a pulverulent mixture of tetraacetylethylenediamine and sodium triphosphate is prepared: the tetraacetylethylenediamine used has an average particle diameter of 0.130 mm and does not contain any particle diameter of more than 0.300 mm; and the sodium triphosphate has an average particle diameter brought to 0.06 mm, by grinding. 7.5 kg'of tetraacetylethylenediamine and 2.5 kg of sodium triphosphate are dry-mixed in a.Y-type rotating mixer: the operation lasts 15 minutes. kg of this dry mixture are introduced into a coating drum of diameter 1 m, the stainless steel bowl of which is driven with a rotational movement of 25 rpm.

In addition, 5 litres of a 5% strength by weight solution of sodium carboxymethylcellulose (BLANOSE BWS) are prepared and heated to a temperature of 50°C; the viscosity of the sodium carboxymethylcellulose used is 120 eps when measured at 50°C on a 5% strength solution, using a shear viscometer (RHEOMAT 15): the velocity gradient used is 43 second This solution is sprayed onto the dry mixture in motion in the coating drum.

The solution of sodium carboxymethylcellulose is sprayed with the aid of a spraying nozzle, under a pressure of 4 bars, onto the pulverulent mixture of tetraacetylethyl enedi-amine and sodium triphosphate, for a period of about 30 minutes.

Granules having the composition given above, which are dry in appearance and relatively firm, are extracted from the coating drum.

The granules obtained are passed through sieves having mesh sizes of 0.63 mm and 2.00 mm.

The following particle size distribution is obtained: fraction smaller than 0.63 mm 13.6% fraction between 0.63 and 2.00 mm 70.9% fraction iarger than 2.00 mm 15.5% EXAMPLE 2 In this Example, granules having the same composition by weight as given above are prepared from tetraacetylethylenediamine and sodium triphosphate having the following characteristics: ' the tetraacetylethylenediamine is in the form of a ground powder, the average particle diameter of which is equal to 0.050 mm and which does not contain any particle with a diameter of more than 0.300. mm and less than 5% of particles with a diameter of less than 0.010 mm; and the sodium triphosphate is also ground until particles with an average diameter of 0.030 mm are obtained, and does not contain any particle with a diameter of more than 0.060 mm.

The other conditions are identical to those of Example 1.

Granules having the following particle size distribution are obtained: fraction smaller than 0.63 mm 8.2% fraction between 0.63 and 2.00 mm 75 % fraction larger than 2.00 mm 16.3% EXAMPLE 3 The method of preparation of the granules described in Example 1 is repeated, the only difference being that the tetraacetylethylenediamine used has an average particle diameter of 0.180 mm and does not contain any particle with a diameter of more than 0.300 mm.

Granules having the following particle size distribution are obtained: fraction smaller than 0.63 mm 15.5% fraction between 0.63 and 2.00 mm 73.5% fraction larger than 2.00 mm % £> A o ** 2) Physico-chemical properties of the granules of the invention The granules prepared according to Examples 1 to 3 are subjected tq a series of measurements and tests in order to demonstrate their physico-chemical properties.

In the various tests, the particle size fraction of 0.63 to 2.00 mm is used. a) Bulk density The weight of 1 cm3 of granules is determined by 10 weighing 100 cm3 of tapped and untapped granules.

The results obtained are as follows: Granules Example 1 Granules Example 2 Granules Example 3 Tapped granules 0.59 g/cm3 0.62 g/cm3 0.68 g/cm3 Untapped granules 0.54 g/cm3 0.58 g/cm3 0.63 g/cm3 b) Firmness of the granules The granules are subjected to a mechanical treatment and their firmness is then evaluated by determining the percentage of fine particles formed by passage through 2o a sieve, the mesh size of which is equal to 2/3 of the diameter of* the smallest granule.

The mechanical operation consists in placing 200 g of granules in a 2 litre glass flask and rotating the flask at 40 rpm for 1 hour.

The percentage of fines is measured by passage through a standardised AFNOR sieve having a mesh size of 0.4 mm.

The percentages of fines obtained show that the granules are firm because only a very small proportion are degraded.

Granules Example 1 Granules Example 2 Granules Example 3 % of fines 0.5 0.4 0.5 c) Kinetics of release of the tetraacetylethylenediamine This test makes it possible to evaluate the rate of formation of the peracetic acid and to confirm the absence of insoluble materials after total perhydrolysis and hydrolysis of the tetraacetylethylenediamine.

The peracetic and acetic acids formed by perhydrolysis and hydrolysis of the tetraacetylethylenediamine released are neutralised so as to keep the pH constant at 10.

By way of comparison, a test is carried out in which the tetraacetylethylenediamine is not coated: the tetraacetylethylenediamine used has an average particle diameter of 0.130 mm, 0.050 mm or 0.180 mm, that is to say the same particle size as that of the tetraacetylethylenediamine introduced into the granules to be tested.

The half-reaction times (tj.) are then determined, these corresponding to the formation of half the amounts of peracetic and acetic acids, relative to the amount of tetraacetylethylenediamine introduced.

In practice, a solution containing 1.58 g/litre jio of sodium perborate tetrahydrate is prepared, which gives a pH of 10.

An accurately determined concentration of about 0.5 g/litre of tetraacetylethylenediamine, in the case of the comparison test, or the corresponding amount of granules in the case of the test for the products of the invention, is added, at a temperature which is kept constant (25°C and 50°C). 0.5 N sodium hydroxide solution is then added so as to keep the pH at 10.

The amounts of peracetic and acetic acids formed are thus determined.

The following half-reaction times are determined (the half-reaction times are expressed in minutes): EXAMPLE 1 t1 at 25°C 2 tl 2 at 50°C Granules of coated TAED 1.8 0.75 TAED without coating 3 0.75 EXAMPLE 2 t. at 25°C 2 tl 2 at 50°C Granules of coated TAED 1.75 0.5 TAED without coating 2.75 0.7 EXAMPLE 3 t. at 25°C 3 t. at 50°C 2 Granules of coated TAED 2.3 1 TAED without coating 3.3 0.9 * TAED : Tetraacetylethylenediamine A distinct improvement in the rate of formation of the acids at low temperature is observed, showing a rapid release of the tetraacetylethylenediamine crystals.

Furthermore, it is found that there are no insoluble materials after total hydrolysis and perhydrolysis, d) Storage stability As the main object of the coating is to protect the tetraacetylethylenediamine, during storage, from the action of the other constituents of the detergent composition which are likely to cause its decomposition, the storage stability of tetraacetylethylenediamine having different particle sizes and coated in the form of granules of the invention will be demonstrated. By way of comparison, a test is carried out with uncoated tetraacetylethylenediamine having the same particle size as that of.the tetraacetylethylenediamine introduced into the granules to be tested.

The granules of the invention or the uncoated tetraacetylethylenediamine are mixed with a detergent composition having the following formulation: S31S2 sodium dodecylbenzenesulpho'nate (ERGANOL 25 % AT3) sodium stearate 3 % fatty alcohol containing 18 carbon atoms and 12 units of ethylene oxide (CEMULSOL DB 6-18) 3 % fatty alcohol containing 18 carbon atoms and 50 units of ethylene oxide (CEMULSOL DB 25-17) 2 % sodium triphosphate 27.5% sodium pyrophosphate (neutral - anhydrous) 0.5% sodium orthophosphate (anhydrous) 0.5% sodium disilicate 8.6% sodium carboxymethylcellulose (BLANOSE B.W.S.) 1.5% distyrylbiphenyl derivative (TINOPAL fluorescent brightener) 0,4% alkaline protease (ESPERASE NOVO enzyme) 0.3% sodium perborate tetrahydrate , 15 % granules of the invention in an amount ) ) expressed as tetraacetylethylenediamine ) ) 3 % or tetraacetylethylenediamine without ) ) coating ) sodium sulphate qsp 100 % The test is carried out on ten 1 g samples of the detergent composition defined above, containing either the granules of coated tetraacetylethylenediamine or the tetraacetylethylenediamine without coating, which is placed in a glass powder flask, which is itself placed, open, in a packet of detergent so as to simulate the usual conditions of storage of detergents. The storage is effected at 40°C in an atmosphere with a relative humidity of 80%.

After storage times of 8, 18 and 43 days, the samples are removed and the tetraacetylethylenediamine is recovered in the presence of all the components of the detergent composition, and the loss in activity of the tetraacetylethylenediamine is then determined.

The principle of the method consists in determining the peracetic acid formed by perhydrolysis of the residual tetraacetylethylenediamine, in a basic medium.

In the presence of potassium iodide, the peracetic acid formed oxidises the latter, and the iodine released is determined with a standardised solution of sodium thiosulphate.

The experimental procedure is explained below: First, the contents of the powder-flasks are crushed on the bottom of a mortar, and they; are then dissolved by adding 15 cm3, of dimethylformamide and stirring the resulting the mixture vigorously for 20 minutes. cm3 of a solution containing 0.15 g/litre of hexapotassium ethylenediaminetetra-(methylenephosphonate), marketed under the name Dequest 2044, are added to the suspension obtained.

The mixture is stirred for exactly 5 minutes. ύ j j-ΰ λ The mixture-is then transferred rapidly and quantitatively into a beaker containing 100 g of crushed ice and 10 cm3 of glacial acetic acid.

About 1 g of potassium iodide is then added and the iodine released is determined with a standardised 0.1N solution of sodium thiosulphate, in the presence of starch paste.

The results obtained are as follows (the loss in activity is expressed as a percentage of the initial activity): Loss in activity (ii 1 %) 0 days 8 days 18 days 43 days EXAMPLE Granules of coated TAED 0 - 2.6 - 7.4 -13 1 TAED without coating 0 -35 -50 -64 EXAMPLE Granules of coated TAED 0 - 3.2 -8.5 -15.2 2 TAED without coating 0 -40 -56 -71.5 EXAMPLE Granules of coated TAED 0 - 2 - 6.5 -12.5 3 TAED wi thout coating 0 -23 -38 -52.1 * TAED : Tetraacetylethylenediamine Analysis of this table shows that the granules of the invention have a very good storage stability, and the tetraacetylethylenediamine contained in the granules is therefore effectively protected against the other constituents of the detergent composition. 3) Detergency test In this test, the behaviour of the granules of the invention during washing is followed in order to determine whether or not they have an adverse influence on the bleaching.

Standard soiled fabrics are used, with stains which are coloured and hence sensitive to bleaching, namely wine soil or tea soil deposited on cotton test-pieces of dimensions 10 x 12 cm (fabrics originating from the St. Gall laboratory).

The reflectance of the soiled fabrics before washing is measured on a GARDNER instrument (GARDNER INSTRUMENTS).

The soiled cotton test-pieces are washed in a LINI-TEST apparatus (ORIGINAL HANAU), which simulates a 20 minute washing cycle at 60°C. cotton test-pieces are introduced into each chamber, together with 300 cm3 of the detergent composition defined for the storage stability tests, in a concentration of 8 g/litre.

After washing, the test-pieces are dried in the open air and then measured again on the GARDNER reflectometer.

The bleaching effectiveness is given by the variation in reflectance before and after washing.

The following results are obtained: Bleaching effectiveness wine soil tea soil EXAMPLE Granules of coated TAED 24.0 14.0 1 TAED without coating 23.8 13.6 EXAMPLE 2 Granules of coated TAED 23.8 14.5 TAED without coating 24.1 14.0 EXAMPLE Granules of coated TAED 23.8 13.9 3 TAED without coating 22.4 13.0 * TAED : Tetraacetylethylenediamine It is therefore noted that the coating agent and the particle size of the tetraacetylethylenediamine used in the bleaching granules of the invention do not cause any substantial reduction, in the bleaching effectiveness, compared with the uncoated activator; furthermore, it is noted that very good bleaching performance characteristics are always obtained, irrespective of the particle size of the tetraacetylethylenediamine chosen within the range defined according to the invention.

In conclusion, an advantage of the present invention is that it makes available a flexible process for the manufacture of granules containing a high proportion of tetraacetylethylenediamine (more than 55% by weight), which makes it possible to granulate and coat any type of tetraacetylethylenediamine with a particle size of 0.02 to 0.25 mm, whilst at the same time always resulting in granules having a good storage stability and a good bleaching effectiveness.

Claims (22)

1. Granules suitable for use as bleaching activator which comprise from 55 to 90% by weight of tetraacetylethylenediamine and from 10 to 45% by weight of a coating agent which comprises an alkali metal polyphosphate 5 and an alkali metal cellulose derivative.

2. Granules according to claim 1, in which the coating agent comprises sodium triphosphate and sodium carboxymethylcellulose.

3. Granules according to claim 2, in which 10 the coating agent comprises sodium triphosphate in an amount such that its weight ratio to the amount of tetraacetylethylenediamine used is from 1/10 to 4.04/5 and sodium carboxymethylcellulose in an amount such that its weight ratio to the amount of tetraacetylethylenediamine 15 used is from 1/100 to 1/10.

4. Granules according to claim 3 in which the said weight ratios are 1/4 to 2/3 and 1/30 to 1/15, respectively.

5. Granules according to any one of claims 1 to 4, which comprise: from 60 to 75% by weight of tetraacetylethylenediamine , 5 at least 20% by weight of sodium triphosphate and from 2 to 4% by weight of sodium carboxymethylcellulose.

6. Granules according to any one of claims 10 1 to 5, in which the tetraacetylethylenediamine has a particle size of 0.02 to 0.25 mm.

7. Granules according to claim 6 in which the tetraacetylethylenediamine has a particle size of 0.05 to 0.15 mm. 15

8. Granules according to any one of claims 2 to 7, in which the sodium triphosphate has a particle size of 0.02 to 0.08 mm.

9. Granules according to claim 8 in which the sodium triphosphate contains an amount of other metal 20 ions which does not exceed 200 ppm.

10. Granules according to claim 9 in which the amount of said other metal ions is from 20 to 100 ppm.

11. Granules according to any one of claims 1. to 10, which have a diameter from 0.4 to 2.0 mm.

12. Granules according to claim 11 which have a diameter from 0.6 to 1.2 mm.

13. Granules according to claim 1 substantially as described in any one of the Exanples. 5 14. Process for the preparation of granules as claimed in any one of claims 1 to 13 which comprises preparing a pulverulent mixture of tetraacetylethylenediamine and an alkali metal polyphosphate, and spraying a solution (as hereinbefore 10 defined) of an alkali metal cellulose derivative onto a moving bed of the mixture. 15. Process according to claim 14 which comprises preparing a pulverulent mixture of tetraacetylethylenediamine and sodium triphosphate, 15 pouring the resulting mixture into a coating drum with a cylindrical bowl, spraying a solution (as hereinbefore defined) of sodium carboxymethylcellulose onto the mixture, set in motion by the rotation of the coating drum, and discharging the granules obtained. 20 16. Process according to claim 14 or 15 in which the charge of the coating drum, consisting of the tetraacetylethylenediamine and the sodium triphosphate, is 30 to 100 kg/m^ of coating drum. 17. Process according to claim 16 in which the 25 charge is 40 to 80 kg/m of coating drum. 18. Process according to any one of claims 15 to 17 in which the speed of rotation of the coating drum is such that the tangential speed of the bowl of the coating drum is 0.5 to 3 m/second. 5 19. Process according to claim 18 in which the said tangential speed is 1 to 2 m/second. 20. Process according to any one of claims

14. To 19 which comprises preparing a solution of sodium carboxymethylcellulose having a viscosity of less than 10 200 cps,keeping said solution at a temperature from 30 to 80°C, and spraying it under a pressure of 2 to 10 bars onto the pulverulent mixture, in motion, of tetraacetylethylenediamine and sodium triphosphate. 21. Process according to claim 20 in which the

15. Said viscosity is 100 to 150 cps and said pressure is 4 to 5 bars. 22. Process according to any one of claims 15 to 21 in which the average residence time of the granules in the coating drum is 10 to 60 minutes.

16. 20 23. Process according to any one of claims 14 to 22, in which the granules are sifted and dried.

17. 24. Process according to claim 14 substantially as described in any one of the Examples.

18. 25. Granules as defined in claim 1 whenever 25 prepared by a process as claimed in any one of claims 14 to 24. Ο Ο 1 Ο Λ

19. 26. A detergent and bleaching composition which comprises at least one surface-active agent, a per-compound which liberates hydrogen peroxide in aqueous solution, a builder and bleaching activator granules as claimed in any one 5 of claims 1 to 13 and 25.

20. 27. A composition according to claim 26 which comprises: from 5 to 50% by weight of anionic, non-ionic, cationic or amphoteric surface-active agent or a mixture 10 thereof, from 10 to 60% by weight of builder, from 5 to 35% by weight of per-compound and from 1 to 10% by weight of tetraacetylethylenediamine in the form of said granules. 15

21. 28. A composition according to claim 26 or 27 which comprises: from 5 to 25% by weight of an anionic or nonionic surface-active agent or a mixture thereof, from 10 to 40% by weight of a builder, 20 from 10 to 20% by weight of a per-compound and from 2 to 4% by weight of tetraacetylethylenediamine in the form of said granules.

22. 29. A composition according to any one of claims 26 to 28, in which the per-compound is sodium perborate. 25 30. A composition according to claim 26 substantially as described in any one of the Examples.