EP0561656A1 - Builder based on silicate and a mineral product - Google Patents

Abstract

"Builder" agent, for a detergent composition, consisting of an aqueous solution of an alkali metal silicate, in particular of sodium or potassium, with an SiO2/M2O molar ratio of the order of 1.6 to 4, and of an inorganic product, inert with respect to the silicate, the said inorganic product representing from 5 to less than 55 % of the total weight expressed on a dry basis and the remaining water in combination with the silicate/silicate expressed on a dry basis ratio by weight being greater than or equal to 33/100, preferably greater than or equal to 36/100. Use of this builder agent in detergent compositions, more particularly in powder detergent compositions, in particular for washing machines and dishwashers.

Description

The present invention relates to a "builder" agent consisting of a solution of alkali metal silicates rich in silicon atoms in Q₂ and Q₃ form, this solution being in the presence of a mineral product inert with respect to silicate . This "builder" agent is intended for detergent compositions, in particular for powdered detergents, in particular for washing machines or dishwashers.

The invention also relates to cogranules of hydrated alkali metal silicates and alkali metal carbonates.

The term “builder” is understood to mean any active adjuvant which improves the performance of the surfactants of a detergent composition.

The builder must have a so-called "softening" effect on the water used for washing. It must therefore eliminate the calcium and magnesium which are present in the water in the form of soluble salts, and in the stains of the linen in more or less soluble complex forms. The elimination of calcium and magnesium can be done either by complexation, in the form of soluble species, or by ion exchange, or by precipitation. If precipitation is involved, it must be checked to avoid encrustations on the laundry or on the elements of washing machines.

This precipitation control is in particular obtained by water-soluble polymers having an affinity for calcium and magnesium.

It is also necessary that the builder adds to the emulsifying effect of surfactants vis-à-vis fatty stains a dispersing effect vis-à-vis "pigmentary" stains, such as metal oxides, clays, silica, various dusts, humus, limestone, soot ...

This dispersing effect is generally obtained thanks to the presence of polyanions, providing a high density of negative charges at the interfaces.

The builder must also provide an ionic strength favorable to the functioning of the surfactants, in particular by increasing the size of the micelles.

It must also provide OH⁻ ions, for the saponification of fats and again, for the increase of the negative surface charges of textile surfaces and particulate stains.

Silicates have long been regarded as good detergency builders, but are currently less used in phosphate-free compositions for washing machines.

The most used silicates in this application are those having a SiO₂ / Na₂O molar ratio of between 1.6 and 2.7.

They are marketed either in the form of concentrated solutions containing approximately 35-45% by weight of dry extract, or in the form of powdered atomized and optionally compacted silicates.

Concentrated commercial solutions are most often prepared from completely amorphous silicate called "glassy", also called "water glass".

These soluble glasses are water-solubilized in an autoclave under pressure at 140 ° C. Commercial solutions are thus obtained having a dry extract of about 45% by weight for a silicate of ratio 2 and about 35% for a silicate of ratio 3.5.

The concentrated silicate solutions are introduced by the detergent formulator into the aqueous suspension (slurry) containing the other constituents of the detergent. The slurry is then spray dried. The silicate, coatomised and co-dried with the other constituents, no longer contains approximately 25% of associated water relative to its dry weight, or even less.

As for commercial powder silicate, it is obtained by spray drying of concentrated solutions of glassy silicate; it is necessary to conserve 19 to 22% by weight of water relative to the finished product to ensure good solubility of said product.

It has been found that, when dissolved in a washing bath in the proportion of 1 to 3 g / liter, this powdered silicate which contains only 19 to 22% by weight of associated water (relative to the finished product), has only weak builder properties.

Indeed, this powdered silicate in solution essentially generates monomeric silicic species of formula Si (OX) ₄, where X represents H or Na, having no builder effect. Such monomeric species can only re-associate with each other to form polyanions if the silicate concentration is at least 50 to 500 g / liter and this slowly.

Such silicate concentrations as well as the slow polymerization kinetics of the monomeric species are not compatible with the conditions and the durations of washing in a washing machine.

What has been observed for a powder containing 19 to 22% of chemically associated water (relative to the finished product) is of course valid for formulations containing a silicate containing approximately 25% associated water (relative to dry silicate) ) prepared by introducing a concentrated silicate solution into a slurry, then drying.

The Applicant has found that, when an alkali metal silicate in solution is rich in silicon atoms in Q₂ and Q₃ form, these species found in the form of polyanions have a sufficient lifespan to enable them to play a role of " builder "in detergency when diluted to 1 to 3g / l in a detergent medium.

The expression "silicon atoms in Q₂ and Q₃ form" is a representation of the degree of association of the silicon atoms with each other; "Q₂" means that each silicon atom participates in two -Si-O-Si- bonds, the two remaining bonds being a -Si-O-X termination where X is an alkali metal or H; "Q₃" means that each silicon atom participates in three -Si-O-Si- bonds, the remaining bond being a -Si-O-X termination.

The "builder" agent for a detergent composition, which is the subject of the invention, is characterized in that it consists of an aqueous solution of an alkali metal silicate, in particular of sodium or potassium, of ratio SiO₂ / M₂O molar of the order of 1.6 to 4, and of a mineral product inert with respect to silicate and miscible in said silicate solution, this product representing from 5 to less than 55% of the total weight expressed in dry and the water weight ratio remaining associated with the silicate / silicate expressed in dry being greater than or equal to 33/100, preferably 36/100, M representing an alkali metal.

By "inert" is meant chemically inert.

The mineral products inert with respect to silicate and miscible in the aqueous solution of silicates are preferably water-soluble. Among these products, there may be mentioned in particular. sodium carbonate, sodium sulfate, sodium borate, sodium perborate, sodium metasilicate, phosphates or polyphosphates such as trisodium phosphate, sodium tripolyphosphate ..., these products being present alone or as a mixture between them.

Use is preferably made of products having a detergency activity, and more particularly sodium carbonate.

The mineral product represents from 5 to less than 55%, preferably from 20 to 40%, of the total weight expressed in dry, that is to say of the sum of the weights of the solution expressed in dry and of the mineral product.

The mineral product is either introduced directly into the aqueous solution of alkali metal silicate, or is introduced into water and then mixed, subsequently, with the aqueous solution of alkali metal silicate.

The "builder" agent according to the invention can be in any form, structured (powder, granules, etc.) or not.

Said silicate may have a SiO₂ / M₂O molar ratio of the order of 1.6 to 4, preferably of the order of 1.8 to 3.5.

According to a preferred embodiment of the invention, said "builder" agent consists of an aqueous solution of about 10 to 60%, preferably about 35 to 50% by weight of dry extract of a metal silicate alkaline, especially sodium or potassium.

The concentrated solution of alkali metal silicate used in the "builder" agent is preferably obtained by water-solubilization of "soluble glasses" in an autoclave under pressure at 140 ° C., then optional dilution; it can also be obtained by other known means, such as direct attack on sand with caustic soda in concentrated solution.

• . une solution à 45 % d'extrait sec de silicate vitreux de rapport molaire SiO₂/Na₂O = 2 contient 34 % d'espèces Q₃, 51 % d'espèces Q₂, 12 % d'espèces Q₁ et 3 % d'espèces Q₀.
• . une solution à 35 % d'extrait sec de rapport 3,5 contient 46 % d'espèces Q₃, 27 % d'espèces Q₂, 16 % d'espèces Q₄, 9 % d'espèces Q₁ et 2 % d'espèces Q₀.

NMR analysis shows that:

• . a 45% solution of dry extract of vitreous silicate with a SiO₂ / Na₂O molar ratio = 2 contains 34% of Q₃ species, 51% of Q₂ species, 12% of Q₁ species and 3% of Q₀ species.
• . a 35% solution of dry extract of ratio 3.5 contains 46% of Q₃ species, 27% of Q₂ species, 16% of Q₄ species, 9% of Q₁ species and 2% of Q₀ species.

The term water "associated" with silicate means water from said aqueous solution which is not combined with the mineral product, in particular which is not in the form of a crystallized hydrate.

The weight ratio of water remaining associated with the silicate / silicate expressed as dryness which must be greater than or equal to 33/100, preferably 36/100, corresponds to the need to be in the presence of silicates in polyanionic forms. It is within the reach of those skilled in the art to set the upper limit of this ratio, this limit corresponding, of course, to the limits for which a silicate is kept in powder form with fluid flow ("free flowing"), it is to say usable in detergency. To fix the ideas, the weight ratio of water remaining associated with the silicate / silicate expressed as dry must be less than or equal to approximately 120/100.

The high content of silicate in the products of the present invention makes it possible in particular to obtain "anti-fouling" performances on the laundry or on the elements of washing machines that are very satisfactory.

The "builder" agent, when it is in an unstructured form and in particular in solution, can be used in post addition by spraying on the "bottom of tower" washing powder in the case of an installation by atomization or on mixing the components of the detergent formula in the case of dry mixing, and this within the limit of the adsorption capacity of the powders present. The powder mixture obtained can be dried moderately, if necessary, so that the remaining water weight ratio associated with silicate / silicate expressed as dry remains greater than or equal to 33/100, preferably 36/100.

The amount of silicate solution of this builder agent in solution which can be used preferably corresponds to a dry silicate / detergent powder weight ratio of between 1/100 and 30/100, even more preferably at a ratio of '' about 10/100 to 20/100.

The builder agent of the present invention, when it is in a structured form, can in particular be prepared by contacting an aqueous solution (A) consisting of a mixture of a concentrated aqueous solution of a alkali metal silicate (1) of SiO₂ / M₂O molar ratio of the order of 1.6 to 4, preferably of the order of 1.8 to 3.5, and of a mineral product (2) solution, the mineral product being inert with respect to the silicate and miscible in the aqueous solution (1) and representing from 5 to less than 55% by total weight expressed as dry, with a compound (B) of composition identical to the aqueous solution (A) mentioned above, so that the water weight ratio remaining associated with the total silicate / total silicate expressed as dry, after contacting, is greater than or equal to 33/100, preferably 36 / 100.

In all that follows and that which precedes, "M" represents, unless otherwise stated, an alkali metal.

The aqueous solution (A) was prepared by any means known per se. It can in particular be prepared by introducing the mineral product, in the form of powder or liquid, into the aqueous silicate solution.

By "compound (B) of composition identical to the aqueous solution (A)" is meant any compound comprising an alkali metal silicate and a mineral product as defined above, the mineral product representing from 5 to less than 55% of the total weight expressed in sec. Said compound (B) preferably has a water weight ratio remaining associated with the silicate / silicate expressed as dryness greater than or equal to 33/100, preferably 36/100.

This compound (B) can be obtained by any means known per se. Thus, it can in particular be obtained by drying a solution identical to the aqueous solution (A). This drying is preferably controlled so as to keep the desired proportions of water associated with the silicate, that is to say that the weight ratio of water remaining associated with the silicate / silicate expressed as dry is greater than or equal to 33/100, preferably 36/100.

In the aqueous solution (A), the concentrated aqueous solution of alkali metal silicate preferably has a water weight ratio remaining associated with the silicate / silicate expressed as dryness greater than or equal to 33/100, preferably 36/100.

The contacting operation can be carried out by adding, in particular by spraying (A) onto (B), in any known mixer with high shear, in particular of the LODIGE® type, or in granulation tools (drum, plate, etc.). .) ..., at a temperature of the order of 20 to 95 ° C, preferably of the order of 70 to 95 ° C.

The mineral products which can be used are those already mentioned previously.

The quantity and concentration of the aqueous solution (A) to be used depends on the absorbing and / or adsorbing power of the mineral products present in the solution (A) and the compound (B) with respect to the silicate present in the solution (A) and the compound (B), taking into account a possible possibility for said mineral products to form in particular crystallizable hydrates; the level of water not associated with the silicate which may be in the form of a hydrate in the support can be determined in a known manner by differential thermal analysis or by quantitative X-ray diffraction. The water possibly combined with the support in forms other than hydrates can be determined by appropriate physicochemical methods (thermoporosimetry, thermogravimetry, proton NMR, IR).

The limit of absorbing and / or adsorbing capacity of said mineral products can be determined according to known methods, for example by measuring the evolution of the angle at the base of the landslide as a function of the rate of addition of the solution. silicate.

If necessary, after this contacting of (A) and (B), it is possible to implement a drying step, but this in a moderate manner so as to obtain the desired proportions of water associated with the silicate.

The alkali metal silicate solutions in the form adsorbed and / or absorbed on an alkali metal carbonate and which are in the form of cogranules of hydrated alkali metal silicate and alkali metal carbonate are builder agents of the invention particularly efficient.

• (a). pulvérisation d'une solution aqueuse constituée d'un mélange d'une solution aqueuse de silicate de métal alcalin de rapport molaire SiO₂/M₂O de l'ordre de 1,6 à 4, de préférence de l'ordre de 1,8 à 3,5, et de carbonate de métal alcalin, ce carbonate représentant de 5 à moins de 55 % en poids total exprimé en sec, sur un lit roulant de particules de composition identique au mélange pulvérisé, défilant dans un dispositif rotatif de granulation, la vitesse de défilement des particules, l'épaisseur du lit roulant et le débit de la solution pulvérisée étant tels que chaque particule se transforme en un cogranulé plastique en entrant en contact avec d'autres particules,
• (b). séchage, éventuel, desdits cogranulés obtenus en (a).,

ces étapes étant mises en oeuvre de telle sorte que le rapport final pondéral eau associée au silicate / silicate exprimé en sec soit supérieur ou égal à 33/100, de préférence à 36/100.Said cogranules of hydrated alkali metal silicates and alkali metal carbonates are characterized in that they are capable of being obtained by a process comprising the following stages:

• (at). spraying of an aqueous solution consisting of a mixture of an aqueous solution of alkali metal silicate with a SiO₂ / M₂O molar ratio of the order of 1.6 to 4, preferably of the order of 1.8 to 3 , 5, and of alkali metal carbonate, this carbonate representing from 5 to less than 55% by total weight expressed as dry, on a rolling bed of particles of composition identical to the pulverized mixture, moving in a rotary granulation device, the speed scroll particles, the thickness of the rolling bed and the flow rate of the sprayed solution being such that each particle is transformed into a plastic co-granule by coming into contact with other particles,
• (b). drying, if any, of said co-granules obtained in (a).,

these steps being implemented so that the final water weight ratio associated with silicate / silicate expressed as dry is greater than or equal to 33/100, preferably 36/100.

These cogranules can be used as a simple and effective means of supplying silicate and carbonate in detergent compositions.

By "particles of composition identical to the spray mixture" is meant particles comprising an alkali metal silicate and an alkali metal carbonate representing from 5 to less than 55% of the total weight expressed as dry. These said particles preferably have a weight ratio of water remaining associated with the silicate / silicate expressed as dryness greater than or equal to 33/100, preferably 36/100.

These particles can be obtained by any means known per se.

They can in particular be obtained by drying a solution identical to the aqueous solution consisting of silicate and alkali metal carbonate mentioned above. This drying is preferably controlled so as to keep the desired proportions of water associated with the silicate, that is to say that the weight ratio of water remaining associated with the silicate / silicate expressed as dry is greater than or equal to 33/100, of preferably 36/100.

The rolling bed of particles of composition identical to the sprayed mixture can also be obtained by initially starting with a dry mixture of carbonate and silicate of ratio expressed by weight carbonate / silicate identical to the sprayed solution, until this bed is completely renewed by the co-granules obtained (recycling).

In the aqueous solution consisting of the silicate / carbonate mixture, the concentrated aqueous solution of alkali metal silicate preferably has a weight ratio of water associated with the silicate / silicate expressed as dryness greater than or equal to 33/100, preferably 36 / 100.

Among the alkali metal silicates and carbonates, mention may preferably be made of those of sodium and potassium, and very particularly those of sodium.

Preferably, between steps (a). and (b)., the cogranules obtained in (a) are subjected. to a densification operation.

According to a preferred embodiment of the invention, the silicate solution, used during the preparation of the cogranules, has a dry silicate extract of the order of 10 to 60%, preferably of the order of 35 to 50 %.

The spraying of the aqueous solution based on the silicate / carbonate mixture is carried out at a temperature of the order of 20 to 95 ° C, preferably of the order of 70 to 95 ° C; this can be promoted by the joint introduction (for example using a two-fluid nozzle) of pressurized air at a temperature of the same order.

The carbonates used can be those of common qualities. Preferably, carbonates which dissolve easily and which have a high adsorbent / absorbent capacity are used.

In addition to these carbonate / silicate mixture particles, small amounts (less than 10% of the weight of the cogranules) may be present, other particles, such as anti-deposition polymers (carboxymethyl - cellulose, etc.), enzymes, polyacrylates, ... commonly used in the detergency field, having a diameter and a density close to those of the particles of carbonate / silicate mixture.

The device used to carry out the co-granulation operation by spraying can be any rotary device of the rotating plate, bezel, rotating drum, mixer-granulator type, etc.

A first preferred embodiment of these cogranules consists in using a rotary granulator allowing the particles to travel in a thin layer. Drageeners having an axis of rotation inclined relative to the horizontal at an angle greater than 20 °, preferably greater than 40 °, are particularly well suited; their geometry can be very diverse: frusto-conical, flat, stepped, a combination of these three forms ...

A second preferred embodiment of these cogranules consists in using a rotary drum, the angle of inclination of which is at least 3% and preferably at least 5%.

The particles based on a carbonate / silicate mixture pass at a temperature of the order of 15 to 200 ° C, preferably of the order of 15 to 120 ° C and very particularly of the order of 15 to 30 ° C .

The quantities of solution based on silicate / carbonate mixture to be sprayed and of particles based on silicate / carbonate mixture to be used correspond to a liquid flow rate / particle flow rate (wetting ratio) which can range from 0.05 to 0.8 l / kg, preferably 0.1 to 0.5 l / kg and very particularly 0.15 to 0.3 l / kg, these values being expressed as sodium salts.

The flow rate of the sprayed solution, the speed of movement of particles as well as the thickness of the layer of particles in movement are such that each particle absorbs liquid and agglomerates with the other particles with which it comes into contact in order to obtain plastic granules and not a paste.

The speed of movement of the particles and the thickness of the layer are regulated by the rate of introduction of the particles into the granulation device and by the characteristics of the latter.

The residence time of the particles in a device of the plate or drum type is generally of the order of 15 to 40 minutes.

• . sa géométrie (troncônique, plat, en escalier, ou combinaison des trois formes),
• . ses dimensions (profondeur, diamètre),
• . son angle d'inclinaison,
• . sa vitesse de rotation,
• . les positions relatives des alimentations en solide et en liquide.

Pour un tambour :

• . sa géométrie (diamètre du tube)
• . son angle d'inclinaison
• . sa vitesse de rotation
• . la charge du tube
• . les positions relatives des alimentations en solide et en liquide.

It is within the reach of the skilled person, depending on a given raw material, to adapt the characteristics of the device used to the desired product; to know for a beverage:

• . its geometry (frusto-conical, flat, stepped, or combination of the three forms),
• . its dimensions (depth, diameter),
• . its angle of inclination,
• . its speed of rotation,
• . the relative positions of the solid and liquid supplies.

For a drum:

• . its geometry (tube diameter)
• . its tilt angle
• . its rotation speed
• . tube load
• . the relative positions of the solid and liquid supplies.

The densification operation can be carried out at ambient temperature by rolling in a rotary device the cogranules obtained in step (a), that is to say in the granulation step.

This device can be dependent or independent of that of granulation.

This densification step can advantageously be carried out by introduction and stay of the cogranules in a rotary drum. The angle of inclination of the latter is at least 3%, preferably at least 5%. The dimensions of this drum, its speed of rotation and the residence time of the cogranules depend on the density sought; the residence time is generally of the order of 20 minutes to 3 hours, preferably of the order of 20 to 90 minutes.

Mixer-granulators are also well suited to this densification operation.

The cogranulation and densification operations can therefore be carried out in the same device, for example in a staircase bezel, the densification of the cogranules being obtained by rolling said cogranules on the last steps of the apparatus; similarly, these two operations can be carried out in a drum with two sections.

The cogranules, optionally densified, can therefore be dried by any known means. A particularly effective method is drying in a fluidized bed using an air stream at a temperature of the order of 40 to 90 ° C, preferably from 60 to 80 ° C. This operation is carried out for a period depending on the air temperature, the water content of the cogranules at the outlet of the granulation device and that desired of the dried cogranules, as well as the fluidization conditions; the skilled person knows how to adapt these different conditions to the product sought.

• un silicate de métal alcalin, notamment de sodium ou de potassium, de rapport molaire SiO₂/M₂O de l'ordre de 1,6 à 4, adsorbé et/ou absorbé sur du carbonate de métal alcalin, ce carbonate représentant de 5 à moins de 55 % du poids du silicate adsorbé et/ou absorbé par le carbonate et le rapport pondéral eau restant associée au silicate / silicate exprimé en sec étant supérieur ou égal à 33/100, de préférence à 36/100.
• une densité de remplissage non tassée de l'ordre de 0,4 à 1,5 g/cm3, de préférence de l'ordre de 0,5 à 1,5 g/cm3, et tout particulièrement de l'ordre de 0,75 à 1 g/cm3,
• un diamètre médian (au sens des pourcentages cumulés passants) de l'ordre de 0,4 à 1,8 mm, de préférence de l'ordre de 0,5 à 0,8 mm, avec un écart type log₁₀ de 0,02 à 0,5, de préférence de 0,05 à 0,3.

Cogranules based on hydrated sodium silicates and sodium carbonate, according to the invention, capable of being obtained by the process described above and particularly suitable for the preparation of detergent compositions for dishwashers and dishwashers. linen, are characterized in that they present:

• an alkali metal silicate, in particular of sodium or potassium, of SiO₂ / M₂O molar ratio of the order of 1.6 to 4, adsorbed and / or absorbed on alkali metal carbonate, this carbonate representing from 5 to less than 55% of the weight of the silicate adsorbed and / or absorbed by the carbonate and the weight ratio of water remaining associated with the silicate / silicate expressed as dry being greater than or equal to 33/100, preferably 36/100.
• an uncompressed filling density of the order of 0.4 to 1.5 g / cm3, preferably of the order of 0.5 to 1.5 g / cm3, and very particularly of the order of 0, 75 to 1 g / cm3,
• a median diameter (in the sense of the cumulative passing percentages) of the order of 0.4 to 1.8 mm, preferably of the order of 0.5 to 0.8 mm, with a log standard deviation of 0.02 to 0.5, preferably from 0.05 to 0.3.

Preferably, the weight ratio of water remaining associated with the silicate / silicate expressed as dry must be less than or equal to approximately 120/100.

The process described above, comprising the cogranulation steps, and optionally those of densification and drying, makes it possible to obtain cogranules based on hydrated alkali metal silicates and alkali metal carbonates dissolving rapidly in water.

Thus, the dissolution rates of 90% and 95% in water of the cogranules according to the invention are respectively less than 3 minutes and less than 5 minutes.

The term dissolution rate at 90% or 95% in water means the time necessary to dissolve 90% or 95% of product at a concentration of 35 g / l in water at 20 ° C.

When it is structured (powder, co-granulated, etc.), the builder agent of the invention is used in detergent compositions for dishwashers at a rate of 3 to 90% by weight, preferably 3 at 70% by weight, of said compositions; the quantities used in the compositions for washing machines are of the order of 3 to 60%, preferably of the order of 3 to 40%, of the weight of said compositions (these quantities are expressed by weight of dry silicate by relative to the composition weight).

Next to the builder agent which is the subject of the invention, there is present in the detergent composition at least one surfactant in an amount which can range from 8 to 20%, preferably of the order of 10 to 15. %, of the weight of said composition.

• les agents tensio-actifs anioniques du type savons de métaux alcalins (sels alcalins d'acides gras en C₈ - C₂₄), sulfonates alcalins (alcoylbenzène sulfonates en C₈ - C₁₃, alcoylsulfonates en C₁₂ - C₁₆), alcools gras en C₆ - C₁₆ oxyéthylénés et sulfatés, alkylphénols en C₈ - C₁₃ oxyéthylénés et sulfatés, les sulfosuccinates alcalins (alcoyl- sulfosuccinates en C₁₂ - C₁₆)...
• les agents tensio-actifs non ioniques du type alcoylphénols en C₆ - C₁₂ polyoxyéthylénés, alcools aliphatiques en C₈ - C₂₂ oxyéthylénés, les copolymères bloc oxyde d'éthylène - oxyde de propylène, les amides carboxyliques éventuellement polyoxyéthylénés,
• les agents tensio-actifs amphotères du type alcoyldiméthyl- bétaïnes,
• les agents tensio-actifs cationiques du type chlorures ou bromures d'alkyltriméthylammonium, d'alkyldiméthyléthylammonium.

Among these surfactants, there may be mentioned:

• anionic surfactants such as alkali metal soaps (alkali salts of C₈ - C₂₄ fatty acids), alkali sulfonates (C₈ - C₁₃ alkylbenzene sulfonates, C₁₂ - C₁₆ alkylsulfonates), C₆ - C₁₆ fatty alcohols and sulfated, oxyethylenated and sulfated C₈ - C₁₃ alkylphenols, alkali sulfosuccinates (C₁₂ - C₁₆ alkyl sulfosuccinates) ...
• non-ionic surfactants of the polyoxyethylene C₆ - C₆ alkylphenol type, oxyethylenated C₈ - C₂₂ aliphatic alcohols, ethylene oxide-propylene oxide block copolymers, optionally polyoxyethylenated carboxylic amides,
• amphoteric surfactants of the alkyl dimethyl betaines type,
• cationic surfactants of the chlorides or bromides type of alkyltrimethylammonium, of alkyl dimethylethyl ammonium.

• des "builders" du type:
  • . phosphates à raison de moins de 25 % du poids total de formulation,
  • . zéolithes jusqu'à environ 40 % du poids total de formulation,
  • . carbonate de sodium jusqu'à environ 80 % du poids total de formulation,
  • . acide nitriloacétique jusqu'à environ 10 % du poids total de formulation,
  • . acide citrique, acide tartrique jusqu'à environ 50 % du poids total de formulation, la quantité totale de "builder" correspondant à environ 0,2 à 80 %, de préférence de 20 à 45 % du poids total de ladite composition détergente,
  • . des agents de blanchiment du type perborates, percarbonates, chloroisocyanurates, N, N, N', N'-tétraacétyléthylènediamine (TAED) jusqu'à environ 30 % du poids total de ladite composition détergente,
  • . des agents anti-redéposition du type carboxyméthylcellulose, méthylcellulose en quantités pouvant aller jusqu'à environ 5 % du poids total de ladite composition détergente,
  • . des agents anti-incrustation du type copolymères d'acide acrylique et d'anhydride maléïque en quantité pouvant aller jusqu'à 10 % environ du poids total de ladite composition détergente,
  • . des charges du type sulfate de sodium pour les détergents en poudre en quantité pouvant aller jusqu'à 50 % du poids total de ladite composition.

Various constituents can also be present in the detergent composition, such as:

• "builders" of the type:
  • . phosphates at a rate of less than 25% of the total weight of the formulation,
  • . zeolites up to around 40% of the total formulation weight,
  • . sodium carbonate up to approximately 80% of the total formulation weight,
  • . nitriloacetic acid up to about 10% of the total formulation weight,
  • . citric acid, tartaric acid up to approximately 50% of the total weight of formulation, the total quantity of "builder" corresponding to approximately 0.2 to 80%, preferably from 20 to 45% of the total weight of said detergent composition,
  • . bleaching agents of the perborate, percarbonate, chloroisocyanurate, N, N, N ', N'-tetraacetylethylenediamine (TAED) type up to around 30% of the total weight of said detergent composition,
  • . anti-redeposition agents of the carboxymethylcellulose, methylcellulose type in amounts which can range up to approximately 5% of the total weight of said detergent composition,
  • . anti-scaling agents of the acrylic acid and maleic anhydride copolymer type in an amount which can range up to approximately 10% of the total weight of said detergent composition,
  • . fillers of the sodium sulfate type for powdered detergents in an amount which can range up to 50% of the total weight of said composition.

The following examples illustrate the invention without, however, limiting its scope.

EXAMPLE 1: Synthesis of an agent builder:

- Silicate de sodium:

Solution de rapport molaire SiO₂/Na₂O = 2,8
Extrait sec: 45% en poids
Densité : 1,500
Répartition des espèces polyanioniques (en pourcentage molaire de Silicium): Q₀ = 0,8%, Q₁ = 6,2%, Q₂ et Q₃ = 83%, Q₄ = 10%.

- Carbonate de sodium:

Poudre anhydre
Densité de remplissage non tassée: 1,1g/cm³
Granulométrie: d50 = 0,5 mm.

Products used for this synthesis:

- Sodium silicate:

Solution of molar ratio SiO₂ / Na₂O = 2.8
Dry extract: 45% by weight
Density: 1,500
Distribution of polyanionic species (in molar percentage of Silicon): Q₀ = 0.8%, Q₁ = 6.2%, Q₂ and Q₃ = 83%, Q₄ = 10%.

- Sodium carbonate:

Anhydrous powder
Unfilled filling density: 1.1 g / cm³
Grain size: d50 = 0.5 mm.

Synthesis:

Add the predetermined sodium carbonate to the sodium silicate solution heated to 80 ° C with stirring. Adding water to the sodium carbonate in this case makes it possible to work with a mixed solution, the dry extract of which is identical to the dry extract of the starting silicate solution. The mixing is carried out in such a way that the sodium carbonate represents 30% by total weight expressed on a dry basis of silicate and carbonate.

The mixed solution is dried in an oven in a thin layer at 20 ° C for 20 hours. The solid obtained is then ground using a Forplex ® mill. The last step consists of drying in a fluid bed at 30-40 ° C so as to obtain a solid of the following composition:
Sodium carbonate therefore represents 30% by total weight expressed as dry silicate and carbonate,
The weight ratio of water remaining associated with the silicate / silicate expressed as dry is equal to: 49.7 / 100.

The product has the following properties:
Unfilled filling density: 0.8 g / cm³
Grain size: d50 = 0.5 mm, d10 = 0.1 mm, d90 = 1mm
Dissolution: less than 4 minutes for 99% of dissolved product (conductimetric measurement of the aqueous solution at 3g / l of product at 20 ° C)
Calcium sequestration capacity: 197 mg of CaCO₃ per gram of anhydrous product. This sequestration capacity is evaluated by measuring the residual calcium concentration at a time t = 15 minutes, the product to be tested being introduced at a time t = 0 into a solution of known concentration of Calcium (solution buffered at pH 10).

EXAMPLE 2

Manufacturing of co-granules:

Solution de silicate de sodium :

rapport molaire SiO₂/Na₂O = 2,0
extrait sec: 45,5% en poids
densité = 1,54 g/cm³

Silicate atomisé :

rapport molaire SiO2/Na2O = 2,05
extrait sec = 20%
densité = 0,55 g/cm³
granulométrie: d50 = 0,12 mm

Carbonate de sodium:

soude légère
densité = 0,6 g/cm³
granulométrie: d50 = 0,12 mm

The products used are:

Sodium silicate solution:

SiO₂ / Na₂O molar ratio = 2.0
dry extract: 45.5% by weight
density = 1.54 g / cm³

Atomized silicate:

SiO2 / Na2O molar ratio = 2.05
dry extract = 20%
density = 0.55 g / cm³
particle size: d50 = 0.12 mm

Sodium carbonate:

light soda
density = 0.6 g / cm³
particle size: d50 = 0.12 mm

A solution at 38% by weight of carbonate (expressed as dry silicate and carbonate) is prepared at 80 ° C. by mixing a solution of carbonate in the silicate solution of ratio 2. The dry extract of the mixed solution thus prepared is 37.7%.

The granulation of this solution is carried out in a drum of length 1300 mm and diameter 500 mm which rotates at 20 revolutions per minute. Granulation is initiated from a footboard composed of a ground mixture of light carbonate and atomized silicate of ratio 2. The carbonate / silicate composition of this mixture is that of the mixed solution. Granulation takes place in the first part of the drum where the solution is sprayed, via a ramp, onto the powder bed. Drying takes place in the second part of the drum, fitted with lifters, and swept by hot air against the current.

• alimentation en solution mixte:   6 à 8 l/h
• alimentation en poudre (recyclage):   50kg/h
• ratio de mouillage:   0,12 à 0,16 l/kg
• débit d'air de séchage:   110 à 120 m3/h
• température d'air de séchage:   105-110°C
• temps de séjour moyen dans le tambour:   30-40 min.

Granulation, densification and drying are therefore done in the same device. The product leaving the drum is partly recycled at the top of the drum after grinding and sieving the cut: 0.2-1.25 mm. Thus, in established regime, that is to say when the initial footboard is completely renewed by newly manufactured products, the granulation parameters are as follows:

• mixed solution feed: 6 to 8 l / h
• powder feed (recycling): 50kg / h
• wetting ratio: 0.12 to 0.16 l / kg
• drying air flow: 110 to 120 m3 / h
• drying air temperature: 105-110 ° C
• average residence time in the drum: 30-40 min.

• rapport exprimé en sec: carbonate / silicate = 38/62,
• sa teneur en eau associéee au silicate/ silicate exprimé en sec = 51/100
• densité de remplissage non tassée = 0,89 g/cm³,
• granulométrie: d50 = 0,45 µm, d95 = 0,8 mm, avec un écart type log₁₀ de 0,37.

We thus recover cogranules whose characteristics are as follows:

• ratio expressed in dry: carbonate / silicate = 38/62,
• its water content associated with silicate / silicate expressed as dry = 51/100
• unfilled filling density = 0.89 g / cm³,
• particle size: d50 = 0.45 µm, d95 = 0.8 mm, with a log standard deviation of 0.37.

• 90 % en poids du produit se dissout en 50 s (solution aqueuse à 35g/l à 20°C),
• 95% en poids du produit se dissout en 67 s (solution aqueuse à 35g/l à 20°C).
• 99% en poids du produit se dissout en 154 s (solution aqueuse à 35g/l à 20°C).

The granules obtained have the following dissolution times:

• 90% by weight of the product dissolves in 50 s (aqueous solution 35g / l at 20 ° C),
• 95% by weight of the product dissolves in 67 s (35g / l aqueous solution at 20 ° C).
• 99% by weight of the product dissolves in 154 s (35g / l aqueous solution at 20 ° C).

• 90 % en poids du produit se dissout en 55 s (solution aqueuse à 35g/l à 20°C),
• 95% en poids du produit se dissout en 108 s (solution aqueuse à 35g/l à 20°C).
• 99% en poids du produit se dissout en 266 s (solution aqueuse à 35g/l à 20°C).

In comparison, the simple initial dry mixture of carbonate and atomized silicate initially constituting the footboard, which is not the subject of the present invention, has the following dissolution times:

• 90% by weight of the product dissolves in 55 s (aqueous solution at 35g / l at 20 ° C),
• 95% by weight of the product dissolves in 108 s (35g / l aqueous solution at 20 ° C).
• 99% by weight of the product dissolves in 266 s (35g / l aqueous solution at 20 ° C).

Calcium sequestration capacity: 243-249 mg of CaCO₃ per gram of anhydrous product. This sequestration capacity is evaluated as in Example 1.

EXAMPLE 3 Manufacturing of cogranules

The granulation method is the same as in Example 2, but the granulator operates in an open loop, that is to say it is supplied by the dry atomized carbonate / silicate mixture and the mixed solution but without recycling of the product obtained. . There is also simultaneous drying.

• alimentation en solution mixte:   6 à 8 l/h
• alimentation en poudre:   30kg/h
• ratio de mouillage:   0,2 à 0,27 l/kg
• débit d'air de séchage:   110 à 120 m3/h
• température d'air de séchage:   105-110°C
• temps de séjour moyen dans le tambour:   30-40 min.

The granulation parameters are as follows:

• mixed solution feed: 6 to 8 l / h
• powder feed: 30kg / h
• wetting ratio: 0.2 to 0.27 l / kg
• drying air flow: 110 to 120 m3 / h
• drying air temperature: 105-110 ° C
• average residence time in the drum: 30-40 min.

• rapport exprimé en sec: carbonate / silicate = 37/63,
• sa teneur en eau associéee au silicate/ silicate exprimé en sec = 42/100
• densité de remplissage non tassée = 0,54 g/cm³,
• granulométrie: d50 = 0,57 mm, d95 = 0,78 mm, avec un écart type log₁₀ de 0,12.

We thus recover cogranules whose characteristics are as follows

• ratio expressed in dry: carbonate / silicate = 37/63,
• its water content associated with silicate / silicate expressed as dry = 42/100
• unfilled filling density = 0.54 g / cm³,
• particle size: d50 = 0.57 mm, d95 = 0.78 mm, with a log standard deviation of 0.12.

• 90 % en poids du produit se dissout en 55 s (solution aqueuse à 35g/l à 20°C),
• 95% en poids du produit se dissout en 122 s (solution aqueuse à 35g/l à 20°C).
• 99% en poids du produit se dissout en 300 s (solution aqueuse à 35g/l à 20°C).

The granules obtained have the following dissolution times:

• 90% by weight of the product dissolves in 55 s (aqueous solution at 35g / l at 20 ° C),
• 95% by weight of the product dissolves in 122 s (35g / l aqueous solution at 20 ° C).
• 99% by weight of the product dissolves in 300 s (35g / l aqueous solution at 20 ° C).

Calcium sequestration capacity: 245 mg of CaCO₃ per gram of anhydrous product. This sequestration capacity is evaluated as in Example 1.

These cogranules are introduced by dry mixing with additives in order to obtain the following composition for washing machine: Laundry composition parts by weight . granules obtained 40 . Sokalan CP5 ® (BASF copolymer) 4.8 . Tixolex 25 ® (amorphous silico-aluminate from Rhône-Poulenc) 5 . Sodium sulphate 7 . TAED 5 . LAB (80%) ® 6 . Synperonic A3 ® 3 . Synperonic A9 ® 9 . Esperase ® (NOVO enzyme) 0.3 . Tinopal DMSX ® 0.2 . Tinopal SOP ® (brighteners from Ciba-Geigi) 0.2 . Defoamer 2.5 . Carboxymethyl cellulose 2

The soil removal performance test is carried out in a WASCATOR FOM 71 r washing machine.

• cycle utilisé : 60°C
• durée totale du cycle : 70 minutes ; pas de prélavage
• nombres de cycles : 3 par lessive
• dureté de l'eau : 32 degrés hydrotimétriques français
• charge de linge: 3,5 kg de torchons en coton blanc
• tissus testés : par lavage, on introduit, en les épinglant sur des torchons, deux séries de tissus suivants :

Coton gris :

Test-Fabric
Krefeld 10 C
IEC 106
EMPA 101

Polyester/coton gris :

Test-Fabric
Krefeld 20 C
EMPA 104

Taches protéiniques:

Sang (EMPA 111)
Cacao (EMPA 112)
Mixte (EMPA 116)

Taches oxydables:

Thé (Krefeld 10 G)
Coton écru (EMPA 222)
Vin (EMPA 114)

   - Doses de lessives :
   1ère série : 5 g/l soit 5 x 20 = 100 g par lavage
   2ème série: 8 g/l soit 8 x 20 = 160 g par lavageThe test conditions are as follows:

• cycle used: 60 ° C
• total cycle time: 70 minutes; no prewash
• number of cycles: 3 per detergent
• water hardness: 32 French hydrotimetric degrees
• laundry load: 3.5 kg of white cotton tea towels
• fabrics tested: by washing, we introduce, by pinning them on cloths, two series of following fabrics:

Gray cotton:

Test-Fabric
Krefeld 10 C
IEC 106
EMPA 101

Polyester / gray cotton:

Test-Fabric
Krefeld 20 C
EMPA 104

Protein stains:

Blood (EMPA 111)
Cocoa (EMPA 112)
Mixed (EMPA 116)

Oxidizable stains:

Tea (Krefeld 10 G)
Unbleached cotton (EMPA 222)
Wine (EMPA 114)

- Doses of detergents:
1st series: 5 g / l i.e. 5 x 20 = 100 g per wash
2nd series: 8 g / l i.e. 8 x 20 = 160 g per wash

Method for measuring the removal of dirt and stains

Photometric measurements (measurements of the amount of light reflected by the fabric) make it possible to calculate the percentages of soil removal. We use the ELREPHO 2000 device from DATACALOR.

où
   A = réflectance de l'échantillon blanc témoin
   B = réflectance de l'échantillon sali témoin
   C = réflectance de l'échantillon sali après lavageThe elimination of soiling is expressed by the formula: $$\text{Elimination in\% =}\frac{\text{C - B}}{\text{A - B}}\text{X 100}$$

or
A = reflectance of the blank control sample
B = reflectance of the soiled control sample
C = reflectance of the soiled sample after washing

The reflectances are determined using the blue trichromatic component, without the action of optical brighteners. Number of measurements made per sample = 4 Number of samples per wash = 2 Number of washes = 3
Or 4 X 2 X 3 = 24 measurements by soiling, by product and by concentration studied.
The anti-fouling performance test in a washing machine is carried out in a SCHULTESS SUPER 6 DE LUXE drum machine.

• cycle utilisé : 60°C
• durée totale du cycle = 65 minutes; pas de prélavage
• nombre de cycles : 25 lavages cumulés
• dureté de l'eau : 21,2 degrés hydrotimétriques français
• tissu test utilisé : bande témoin répondant exactement aux spécifications développées dans la norme NFT 73.600
• charge de linge : 3 kg de serviettes éponges 100 % coton
• doses de lessive : 5 g/l

The test conditions are as follows:

• cycle used: 60 ° C
• total cycle time = 65 minutes; no prewash
• number of cycles: 25 cumulative washes
• water hardness: 21.2 French hydrotimetric degrees
• test tissue used: control strip exactly meeting the specifications developed in standard NFT 73.600
• laundry load: 3 kg of 100% cotton terry towels
• detergent doses: 5 g / l

The test pieces which have been washed 25 times are dried: they are weighed and calcined at 900 ° C.

The% of weight of ash is measured relative to the weight of the starting test pieces.

The results of the various tests are shown in Table I.

COMPARATIVE EXAMPLE 4 Manufacturing of co-granules:

The granulation system consists of a drum rotating at 40 revolutions per minute identical to that described in Example 2. The outlet diaphragm is adjusted so that the residence time of a particle is of the order of 15 to 20 minutes.

The drum is continuously fed at a flow rate of 37 kg / h by a carbonate powder having the same characteristics as that of the powders of Example 2.

On this powder brought into rotation in the drum is sprayed with air at 80 ° C via a bi-fluid nozzle with flat jet located at the first third of the drum, a silicate solution identical to that of Example 2 at 80 ° C with a flow rate of 18l / h.

The cogranules leaving the drum are at room temperature and have a density of 0.68 g / cm3.

The cogranules are then densified batchwise for one hour in a rotary drum with smooth walls of diameter 500 mm, length 1300 mm and having an inclination of 5%.

The drum rotation speed is 20 rpm.

The granules thus obtained are dried in a fluidized bed at a temperature of the order of 65 ° C (temperature of the fluidizing air equal to 70 ° C) for 15 min.

• rapport exprimé en sec: carbonate / silicate = 66/34,
• sa teneur en eau associéee au silicate/ silicate exprimé en sec = 61 /100

The dried product has the following characteristics:

• ratio expressed in dry: carbonate / silicate = 66/34,
• its water content associated with silicate / silicate expressed as dry = 61/100

Calcium sequestration capacity: 285 mg of CaCO₃ per gram of anhydrous product. This sequestration capacity is evaluated as in Example 1.

The granules exhibit excellent storage behavior.

These co-granules are introduced by dry mixing with additives in order to obtain a composition for washing machine identical to that described in Example 4 (with the exception of the co-granule).

The dirt removal and encrustation performance tests are also carried out on this detergent composition.

The results are collated in Table I. COMPARATIVE EXAMPLE 4 EXAMPLE 3 5G / L INLAYS 3.72 2.88 WASHING PERFORMANCE Gray cotton 5 g / l 40 ° C 32.2 32.9 Gray cotton 8 g / l 40 ° C 47 41.9 Gray cotton 5 g / l 60 ° C 51.4 49 Gray cotton 8 g / l 60 ° C 56.3 54.8 46.73 44.65 Polyester / Cotton gray 5 g / l 40 ° C 39.2 35.3 Polyester / Gray cotton 8 g / l 40 ° C 56.1 50.1 Polyester / Cotton gray 5 g / l 60 ° C 56.8 55.7 Polyester / Cotton gray 8 g / l 60 ° C 65.4 62.3 54.38 50.85 Protein stains 5 g / l 40 ° C 38.8 34.8 Protein stains 8 g / l 40 ° C 46.3 40.2 Protein stains 5 g / l 60 ° C 50.6 51 Protein stains 8 g / l 60 ° C 58.6 56.4 48.58 45.60 Oxidizable stains 5 g / l 40 ° C 42.1 42.1 Oxidizable stains 6 g / l 40 ° C 59.5 55 Oxidizable stains 5 g / l 60 ° C 75.7 72.8 Oxidizable stains 8 g / l 60 ° C 83.8 82 73 69.93 GENERAL PERFORMANCE 55.67 52.76

Claims (19)

1) "Builder" agent for a detergent composition, characterized in that it consists of an aqueous solution of an alkali metal silicate with a SiO₂ / M₂O molar ratio of the order of 1.6 to 4, and of a mineral product inert with respect to silicate and miscible in said silicate solution, this product representing from 5 to less than 55% of the total weight expressed in dry matter and the water weight ratio remaining associated with silicate / silicate expressed in dry matter being greater or equal to 33/100, preferably 36/100, M representing an alkali metal. 2) Agent "builder" according to claim 1 characterized in that the mineral product is sodium carbonate, sodium sulfate, sodium borate, sodium perborate, sodium metasilicate, phosphates or polyphosphates such as phosphate trisodium, sodium tripolyphosphate, these products being present alone or as a mixture. 3) Agent "builder" according to claim 1 or 2 characterized in that the mineral product represents from 20 to 40% of the total weight expressed in dry. 4). Builder agent according to any one of the preceding claims, characterized in that the aqueous alkali metal silicate solution has a dry silicate extract of the order of 10 to 60%, preferably of the order of 35 to 50 %. 5). Builder agent according to any one of the preceding claims, characterized in that the water weight ratio remaining associated with the silicate / silicate expressed as dry is less than or equal to approximately 120/100. 6). Builder agent according to any one of the preceding claims, characterized in that the SiO₂ / M₂O molar ratio is of the order of 1.8 to 3.5, M representing an alkali metal. 7). Cogranules of hydrated alkali metal silicates and alkali metal carbonates characterized in that they are capable of being obtained by a process comprising the following steps: (at). spraying of an aqueous solution consisting of a mixture of an aqueous solution of alkali metal silicate with a SiO₂ / M₂O molar ratio of the order of 1.6 to 4, preferably of the order of 1.8 to 3 , 5, and of alkali metal carbonate, this carbonate representing from 5 to less than 55% by total weight expressed as dry, on a rolling bed of particles of composition identical to the pulverized mixture, moving in a rotary granulation device, the speed of movement of the particles, the thickness of the rolling bed and the flow rate of the sprayed solution being such that each particle is transformed into a plastic cogranulate by coming into contact with other particles, (b). drying, if any, of said co-granules obtained in (a)., these steps being implemented so that the weight ratio of water associated with silicate / silicate expressed as dry is greater than or equal to 33/100, preferably 36/100, M representing an alkali metal. 8). Cogranules according to claim 7, characterized in that the alkali metal silicate and the alkali metal carbonate are those of sodium or potassium and preferably those of sodium. 9). Cogranules according to claim 7 or 8 characterized in that, between steps (a) and (b), the cogranules obtained in (a) are subjected to a densification operation. 10). Cogranules according to any one of Claims 7 to 9, characterized in that the silicate solution has a dry silicate extract of the order of 10 to 60%, preferably of the order of 35 to 50%. 11). Co-granules according to any one of Claims 7 to 10, characterized in that step (a) is carried out at a temperature of the order of 20 to 95 ° C. 12). Cogranules according to any one of Claims 7 to 11, characterized in that the particles of composition identical to the sprayed mixture are obtained by drying a solution identical to said aqueous solution consisting of silicate and alkali metal carbonate. 13). Cogranules according to any one of the renditions 7 to 12, characterized in that the granulation device is a rotary granulator allowing the particles to travel in a thin layer. 14). Co-granules according to claim 13, characterized in that the rotary granulator is a bezel. 15). Cogranules according to any one of Claims 7 to 12, characterized in that the granulation device is a drum. 16). Cogranules according to any one of the renditions 7 to 15 characterized in that the particles of composition identical to the pulverized mixture pass at a temperature of the order of 15 to 200 ° C. 17). Cogranules according to any one of Claims 7 to 16, characterized in that the quantities of solution based on silicate / carbonate mixture to be sprayed and of particles based on silicate / carbonate mixture to be used correspond to a liquid flow / particle flow rate which can range from 0.05 to 0.8 l / kg, preferably from 0.1 to 0.5 l / kg, these values being expressed as sodium salts. 18). Cogranules according to any one of the renditions 7 to 17 characterized in that the densification operation is carried out at ambient temperature by rolling the cogranules obtained in step (a) in a rotary device. 19). Spherical co-granules based on hydrated alkali metal silicates and alkali metal carbonate, characterized in that they have: an alkali metal silicate, in particular of sodium or potassium, of SiO₂ / M₂O molar ratio of the order of 1.6 to 4, adsorbed and / or absorbed on alkali metal carbonate, this carbonate representing from 5 to less 55% of the weight of the silicate adsorbed and / or absorbed by the carbonate and the weight ratio of water remaining associated with the silicate / silicate expressed as dry being greater than or equal to 33/100, preferably 36/100. - an uncompressed filling density of the order of 0.4 to 1.5 g / cm3, preferably of the order of 0.5 to 1.5 g / cm3, and very particularly of the order of 0 , 75 to 1 g / cm3, - a median diameter of the order of 0.4 to 1.8 mm, preferably of the order of 0.5 to 0.8 mm, with a standard deviation log₁₀ of 0.02 to 0.5, preferably from 0.05 to 0.3.