FR2808267A1 - Precipitated thickening silica granules used in dental products have specified properties - Google Patents

Abstract

Precipitated thickening silica granules comprises a mixture of silicas (a) and (b) of average diameter at least 100 (120-650) microns, cohesion factor at least 0.3 (0.4-1), DOP at least 230 (290) ml/100 g and D50 at least 14 (14-30) microns are obtained by wet granulation and contain water at 25-40 (30-35) wt.% and a weight ratio of (a)/(b) of 1.5-6 (2-3.5).

Description

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HIGH STRUCTURE PRECIPITATION SILICA GRANULES OBTAINED
BY GRANULATION AND THEIR USE AS A THICKENING AGENT
IN DENTAL COMPOSITIONS
The subject of the present invention is high-structure (thickening) silica granules of variable cohesion obtained by granulation of at least two high-structure precipitation silicas (thickeners) and their use in compositions for cleaning and / or treatment. skin, teeth and other hard surfaces; it relates more particularly to medium cohesion granules that can be used in dental compositions as a thickening agent to provide sensory properties in the mouth.

 It is known to prepare silica granules of 0.03 to 3 mm by granulation, by water, of so-called "thickening" silica of primary particles of 0.01 to 0.2 m.

These granules can be used in toothpaste compositions; they are friable under the brushing conditions (GB-A-2,272,640).

 It is known to granulate with water mixtures of silica of low structure (abrasive) and of high structure (thickening) and to adjust the cohesion of the agglomerates obtained by the ratio between the two types of silica; these agglomerates are friable to brushing and may be used as a cleaning agent providing sensory benefit in toothpaste compositions (WO 96/09033 and WO 96/09034). This document teaches that agglomerates formed from high-silica (thickening) alone do not break during the time allotted to brushing and that agglomerates formed from low-silica (abrasive) silica alone are not cohesive and break when preparing toothpaste.

 The Applicant has found silica granules of high structure (thickening) and not containing low-silica (abrasive) obtained by granulation, whose cohesion can be controlled by the granulation process and be adapted to the desired application .

 The Applicant has found in particular thickening silica granules containing no abrasive silica and having a cohesive force sufficient to be introduced into the toothpaste compositions, but however limited to be partially breakable brushing. These cogranules can be used as a thickening agent in dental or oral compositions, which agent also provides sensory properties in the mouth, namely the perception of a roughness perception property at the beginning of brushing, then perception of creaminess and a phenomenon of burst granules (breackdown perception) as the progress of brushing.

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moins 100 pm, de préférence de 120 à 650 um, obtenus par granulation par voie humide de silice de précipitation de haute structure (épaississante), séchage et éventuellement tamisage, lesdits granulés étant caractérisés en ce qu'ils présentent un facteur de cohésion FC d'au moins 0,3, de préférence de 0,4 à 1, et en ce que l'étape de granulation est réalisée dans un appareil de granulation faiblement cisaillant, par mise en #uvre * d'au moins une poudre de silice de précipitation (a) de haute structure présentant . une DOP d'au moins 230 ml/1 00g, de préférence d'au moins 290 ml/1 00g . un diamètre médian D50a d'au moins 14 m, de préférence d'au moins de 14 à 50um, tout particulièrement de 14 à 30um * de particules d'au moins une silice de précipitation (b) présentant

. une DOP d'au moins 230 ml/1 00g, de préférence d'au moins 290 mll100g . un diamètre médian D50b d'au moins 0,3 m et d'au plus 13um, de préférence de 0,5 à 13 m * et d'eau (W) comme liant l'extrait sec du mélange formé par les silices (a) et (b) et l'eau (W) étant de 25 à 40% en poids, de préférence de 30 à 35% en poids, le rapport pondéral (a)/(b), exprimé en sec, de la silice (a) à la silice (b) allant de 1,5 à 6, de préférence de 1,8 à 4, tout particulièrement de 2 à 3,5. These granules having a perfectly homogeneous silica structure, namely consisting essentially of thickening silica, can be used in a relatively large amount in dentifrices or dental compositions, without risk of damaging tooth enamel, and can replace at least partially usual thickeners such as gums, thickening silica powders
A first subject of the invention consists of precipitation silica granules of high structure (thickening), having a median diameter of from

less than 100 μm, preferably from 120 to 650 μm, obtained by wet granulation of high structure precipitation silica (thickening), drying and optionally sieving, said granules being characterized in that they exhibit a cohesion factor FC d at least 0.3, preferably from 0.4 to 1, and in that the granulation step is carried out in a weakly shearing granulation apparatus, using at least one silica powder of at least precipitation (a) of high structure presenting. a DOP of at least 230 ml / 100 g, preferably at least 290 ml / 100 g. a median diameter D50a of at least 14 m, preferably at least 14 to 50 μm, most preferably 14 to 30 μm * particles of at least one precipitation silica (b) having

. a DOP of at least 230 ml / 100 g, preferably at least 290 ml / 100 g. a median diameter D50b of at least 0.3 m and at most 13 μm, preferably 0.5 to 13 m * and water (W) as binder the dry extract of the mixture formed by the silicas (a ) and (b) and the water (W) being from 25 to 40% by weight, preferably from 30 to 35% by weight, the weight ratio (a) / (b), expressed as dry, of the silica ( a) silica (b) ranging from 1.5 to 6, preferably from 1.8 to 4, most preferably from 2 to 3.5.

 For a good realization of this granulation operation, it is preferable that the median diameter D50b of the silica particles (b) is from 1 to 3 times, preferably from 1 to 2 times less than the median diameter D50a of the silica powder particles. (at).

 According to a first embodiment of the invention, the silica particles (b) are used in the form of a dry powder.

The moisture content of the powders (a) and (b) may be of the order of 3 to 15% by weight; this rate is generally of the order of 6 to 12% by weight.

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 According to a second embodiment of the invention, the silica particles (b) are used in the form of a suspension in water (W) and form a binding assembly (L).

This binding group (L) may be a binder assembly (L1) obtained by redispersion in water (W) of silica particles (b) in the form of a dry powder.

Preferably, this binder assembly (L) is a binder assembly (L2) formed by the suspension (cake or "slurry") of precipitated silica (b) directly from the synthesis by precipitation in an aqueous medium of the silica ( b) and before drying said silica. This binder assembly (L2) may contain from 10 to 30%, preferably from 15 to 25%, of its weight of silica (b) expressed in dry matter. This binder assembly (L2) may optionally be diluted by the addition of water up to 5% by weight of silica (b).

 The granulation operation may be carried out by spraying the water (W) or the binding assembly (L) on the silica powders or bringing the water (W) or the binding assembly into contact with each other. (L) and silica powder (s) in a low shear granulation apparatus.

The term "low shear granulation apparatus" is understood to mean a granulation apparatus comprising shearing means capable of developing a peripheral speed at the end of the rotor from 0.5 m.s to less than 4 m.

 Said granulation operation can be carried out continuously or discontinuously.

 The residence time of the raw materials in the granulator (contact time of the raw materials with each other) can generally be of the order of 15 to 45 minutes for a granulator operating in a batch, the granulation time generally being from 10 to 20 minutes. .

This residence time is in particular a function of the granulation apparatus used, its volume, the amount of granulation water used and the particle size distribution of the powder or powders used. The determination of these different parameters as a function of the desired cohesive strength can easily be determined by those skilled in the art.

 The drying operation can be integrated or not be integrated in the granulation operation.

 Preferably, the granulation operation does not include a drying operation. The granulation operation can be carried out preferably at room temperature (temperature of the installation site) in a batchwise manner by spraying the water (W) or the binding assembly (L) on the powder kept in motion or in continuous feed continuously and contacting the water (W) or the binding assembly (L) and the silica powder.

 The product obtained by granulation is then transferred to a drying apparatus (drying oven, fluidized bed, crossed bed or other known means of drying), where it is

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 dried until it has a residual moisture of the order of 3 to 15% by weight (generally of the order of 6 to 12% by weight). The temperature of the drying air may be for example of the order of 100 to 120 C.

 By way of example of granulation apparatuses that can be used to carry out the invention, mention may be made of those of the LODIGE (from Lôdige), WAM (from Wam) or DRAIS (from Drais) type, operating continuously or batchwise.

 For a good realization of the invention, it is preferable that the total amount of water (WT) used in the granulation medium (that is to say the one used as a granulation binder as well as that present in the form of moisture in the silica powder) relative to the total amount (ST), expressed as dry, of silica used will correspond to a weight ratio (WT) / (ST) greater than 1.8 and less than 2.5.

#uvre une poudre de silice (a) dont le diamètre DlOa est d'au moins lem, de préférence d'au moins 3 um, et inférieur à 10m
De même il peut être conseillé, pour une bonne réalisation de l'invention, de mettre en #uvre des particules de silice (b) dont le diamètre D10b est d'au moins 0,1um et d'au plus 7 m. It may be advisable, for a good realization of the invention, to implement

a silica powder (a) having a diameter DlOa of at least 1 μm, preferably at least 3 μm and less than 10 μm
Similarly it may be advisable, for a good embodiment of the invention, to implement silica particles (b) whose diameter D10b is at least 0.1um and at most 7 m.

dans l'eau, celle-ci peut de préférence présenter un diamètre DlOb de 3um à 7um. When the silica (b) is in the form of a dry powder or a redispersed dry powder

in water, it may preferably have a diameter D10b of 3um to 7um.

préférence présenter un diamètre DlOb inférieur à 4um. When the silica (b) is an undried silica suspension resulting directly from the synthesis by precipitation in an aqueous medium of the silica (b), this can

preferably have a diameter D10b less than 4um.

 The granules obtained can then, if necessary, be sieved to eliminate those outside the desired particle size cut.

DOP oil intake of silicas (a) and (b) is determined according to ISO 787/5 by using dioctyl phthalate, on silica particles dried according to the protocol described in this same standard.

Granutometric distribution. starting silicas as well as that of the final granules is controlled by wet laser diffraction in a MALVERN MASTERSIZER apparatus (from Malvern Instruments).

The parameters of the device are set as follows: * 300RF lens (size range 0.05 to 880um) * 3-SiO2 configuration (refractive index 1.4600, 0. 0100) * analysis model: polydisperse * pump and stirring: 60% dispersant: water A dispersion of starting silica or silica granules is prepared.

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The granulometric measurements of the final granules are carried out on the 630um-125um section obtained by sieving.

The particle size distribution is first controlled without ultrasound. This is again checked after subjecting the dispersion to two minutes of ultrasound. The ultrasound power is 100% in the case of starting silicas and 50% in the case of final granules.

The diameter D50 corresponds to the size of not more than 50% by volume of the particles or granules of silica.

The diameter D10 corresponds to the size of not more than 10% of the volume of the particles or granules of silica.

The diameter D90 corresponds to the size of not more than 90% of the volume of the particles or granules of silica.

The FC cohesion force of the granules is determined by the ratio of the D50 of the granules treated with ultrasound (50% power) to the D50 of the granules before ultrasonic treatment.
FC = D50 after ultrasound / D50 without ultrasound
The silica (a) used in powder form, as well as the silica (b) used in the form of a powder or a suspension, are precipitating silicas of DOP oil uptake. less than 230 ml / 100 g, they can be obtained according to known techniques for the preparation of high-silica precipitation or thickening silica from an aqueous solution of an alkali metal silicate (for example a sodium or potassium silicate of molar ratio SiO 2 / M 2 O 2 to 4) and an acidifying agent (for example sulfuric, nitric, hydrochloric, carbonic, acetic, formic acid, etc.).

The precipitated silica slurry formed is then separated to obtain a silica slurry. A silica powder is then obtained by drying. The powder is then optionally milled and sieved if necessary.

 The alkali metal silicate is advantageously sodium silicate. It is preferably used in the form of an aqueous solution having a concentration expressed as SiO 2, of the order of 20 to 350 g / l, preferably of the order of 100 to 260 g / l.

 In a preferred manner, the acidifying agent is sulfuric acid. It can be used in diluted or concentrated form, preferably in the form of an aqueous solution having a concentration of the order of 60 to 400 g / l.

 The silica slurry forming step can be carried out according to various known methods at a temperature of at least 60 ° C, preferably of the order of 70 to 98 ° C, most preferably 80 to 98 ° C.

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 This step can be carried out by progressive neutralization of a base of an aqueous solution of alkali metal silicate optionally containing an electrolyte, by continuous or discontinuous addition of an acid. Such a procedure is described in particular in Examples 1 of documents FR-A-1 054 175 and US-A-2 940 830.

Another method may consist in simultaneously introducing a solution of alkali metal silicate and acid on a base of tank consisting of: - water optionally added with an acid or a base, pH of the order of 4 to
11 - or an aqueous solution of alkali metal silicate optionally containing an electrolyte, optionally partially neutralized with an acid, or a suspension (slurry) of silica, of pH of the order of 6 to 9, the simultaneous introduction of the reagents being carried out either in order to maintain a pH of the medium at a substantially constant value of the order of 7 to 9, or at a constant rate until a pH of about 8 to 9 * is obtained and then, if desired, to introduce a acid until a pH of about 3 to 6 is reached.

 Among the electrolytes that may be present in the stock stem, mention may in particular be made of the soluble salts of the alkali or alkaline earth metals, in particular the salt of the metal of the starting silicate and of the acidifying agent, namely preferably the sulphate of sodium in the case of the reaction of a sodium silicate with sulfuric acid. The amount of electrolyte present can be of the order of 0.1 to 1 mole of alkali metal electrolyte salt or of the order of 10 to 100 mmol of alkaline earth metal electrolyte salt per liter of stock foot. In the case of sodium sulphate, it may be up to 17 g / l, preferably up to 14 g / l of stock.

 Neutralization procedures by simultaneous introduction of silicate and acid in a stock base are described in particular in EP-A-18 866; EP-A-396450; EP-A-520 862; FR-A-2,710,629 and EP-A-670,813.

 The step of separating the slurry can be carried out by filtration or by any other means; operation is preferably coupled with a washing operation.

The filtration / washing steps of the slurry are preferably carried out using a filter press and water as washing agent.

 The cake ("slurry") can then, if necessary, before drying, be disintegrated (that is to say fluidized), for example by simple mechanical stirring using a shearing mobile, possibly with the addition of water or acid.

 The cake, optionally disintegrated, generally having a solids content of the order of 10 to 30%, preferably 15 to 25%, is then dried to obtain a

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 dry powder by any known means, for example in a tunnel or muffle furnace or by atomization in a stream of hot air; the dried silica obtained can have a humidity of the order of 3 to 15%, preferably 6 to 12% by weight.

 In order to obtain the desired median diameter D 50, the powder obtained after drying of the silica cake optionally disintegrated is, if necessary, ground and / or micronized; a step of grinding the silica cake according to the known methods of wet grinding may further be provided.

 In order to obtain the desired median diameter D50 of the binder (L2), the silica cake optionally disintegrated is, if necessary, ground according to the known methods of wet grinding.

 These silicas may have a BET surface area of at least 140 m 2 / g (determined according to the method of BRUNAUER - EMMET - TELLER described in "The Journal of the American Chemical Society", Vol 60, page 309, February 1938 and corresponding to ISO 5794/1 (Annex D)).

 Among the commercially available silicas that may be used as silica powder (a), mention may be made of the silicas known under the names Tixosil 38AB from Rhodia, Hisil 267 from PPG ...

 Among the commercially available silicas that can be used as silica powder (b) which is dry or redispersed in water (W), mention may be made of the silicas known under the names Tixosil 43 from Rhodia, Sident 22S from Degussa, Sorbosil TC15 of Crosfield, Tixosil 333 of Rhodia ...

 Among the silica particles (b) in aqueous suspension forming the binder (L2) that may be used, mention may be made of silica suspensions ("slurry") obtained directly during the synthesis, for example from silicas (a) ci above or their precursors, before drying, said suspensions being crushed and optionally sieved to obtain the desired particle size distribution.

The granules according to the invention may have a DOP of at least 190 ml / 100 g, preferably at least 210 ml / 100 g. '
The granules subject of the invention may be used as additives in compositions for cleaning and / or treating skin, teeth and other hard surfaces. They can be used at a rate of 0.1 to 50% of the weight of said compositions.

They may for example be used as an exfoliating agent in cosmetic compositions (shower gels, creams, etc.) in a proportion of 0.5 to 5% by weight of said compositions, in hard surface cleaning compositions (powders or scouring creams) at 20 to 50% by weight of said compositions.

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 A particular embodiment, constituting a second object of the invention, consists of silica granules of high structure (thickening), capable of being used as thickening agents with sensory effect in the mouth for dental compositions.

. un diamètre médian d'au moins 250 nom, de préférence de 300 à 450 nom, tout particulièrement de 300 à 400 m . et un facteur de cohésion FC de 0,45 à 0,75 , tout particulièrement de 0,5 à 0,7. According to the invention, these are granules prepared according to the granulation process described above and having

. a median diameter of at least 250 nom, preferably 300 to 450 nom, especially 300 to 400 m. and an FC cohesion factor of 0.45 to 0.75, most preferably 0.5 to 0.7.

 Said granules may further comprise coloring agents, opacifying agents (in particular titanium dioxide), perfumes, active agents with respect to the teeth or the oral wall, therapeutic or non-therapeutic, such as fluorinated agents, zinc citrate , anti-scale agents, anti-caries agents ....

 The granules of this second subject of the invention can be used in particular as a thickening agent in oral compositions, in particular in dentifrice compositions (pastes, gels in particular), providing said compositions with sensory properties in the mouth.

Indeed, being of limited cohesion, these granules bring a sensory effect by disintegration to the brushing, resulting in the perception of a certain roughness (roughness perception, crunchy) at the beginning of brushing, then the perception of a phenomenon of bursting granules (breackdown perception) and creaminess as the brushing progresses.

In addition, being obtained from so-called "high-structure" or "thickening" silicas (high DOP oil uptake), they can be used in a relatively large amount in the dental compositions without giving an unpleasant feeling of sand ( "gritty feeling") and without risk of damage to tooth enamel. They can at least partially replace the usual thickeners such as thickening gums or silica powders.

 Said granules can be used in dental or oral compositions, at a rate of 0.1 to 12%, preferably from 0.5 to 10% by weight of said compositions.

 These compositions may also contain other usual ingredients, in particular mineral abrasives, insoluble in water, thickeners, humectants ...

 As abrasive agents, mention may in particular be made of abrasive silicas, calcium carbonate, hydrated alumina, bentonite, aluminum silicate, zirconium silicate, metaphosphates and phosphates of sodium, potassium and calcium.

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 and magnesium. The total amount of powder (s) can be of the order of 5 to 50% of the weight of the dental composition.

 Among the thickening agents, mention may be made, in particular, of thickening silicas in an amount of up to 15% by weight of said composition, xanthan gum, guar gum, carrageenans, cellulose derivatives, alginates, in an amount up to 5% of the weight of said composition ...

 Among the humectants, mention may be made, for example, of glycerol, sorbitol, polyethylene glycols, polypropylene glycols, xylitol, in an amount of the order of 2 to 85%, preferably of the order of 3 to 55% of the weight of dentifrice composition expressed in sec.

These toothpaste compositions may further comprise surfactants, detergents, dyes, antibacterials, fluorinated derivatives, opacifiers, flavors, sweeteners, antiscalants, anti-plaque agents, bleaching agents, sodium bicarbonate, antiseptics, enzymes, natural extracts (chamomile, thyme ...) ...

 The present invention also relates to the use of the above thickening silica granules having an FC cohesion force of the order of 0.45 to 0.75, preferably 0.5 to 0.7 as thickening agent. with sensory effect in the mouth in toothpaste compositions. Said granules may be present in a proportion of 0.1 to 12%, preferably 0.5 to 10% by weight of said compositions.

These compositions can be in the form of a paste, a gel ...

 A final subject of the invention consists of dental compositions, comprising said thickening silica granules above having a cohesion force FC of the order of 0.45 to 0.75, preferably 0.5 to 0, 7; granules may be present in a proportion of 0.1 to 12%, preferably 0.5 to 10% by weight of said compositions.

 The following examples are given for illustrative purposes.

Example 1 Equipment used * MOINEAU volumetric pump * 20 liter LODIGE granulator M20 with plow shares * LECHLER pressure nozzle (Ref .: 460.403.17, 0 0.85 mm)

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D50b 8,71 nom 8,65hum D90b 21,26nom 20,23hum Granulation 3463,4 g de "slurry" de silice sont introduits dans la cuve en verre. L'agitation est mise en marche (réglage vitesse n 6). * 8 liter glass feed tank with stirring * IR balance for dry tests (160 C) Products used * silica powder (a): Tixosil 38AB from Rhodia. particle size distribution (measured in MALVERN 100% US) without ultrasound after ultrasound
D10a 8.43um 7.52um
D50a 24.65um 18.72um
D90a 102.50um 66.25 m. humidity = 10% * silica particles (b): suspension or silica cake (called "silica slurry") of the synthesis of Rhodia Tixosil 38A silica before drying, then grinding. dry extract: 15.3% by weight. particle size distribution (measured in MALVERN 100% US) without ultrasound with ultrasound
D10b 3,59um 3,66um

D50b 8,71 name 8,65hum D90b 21,26nom 20,23hum Granulation 3463.4 g of silica "slurry" are introduced into the glass vessel. Stirring is started (speed setting n 6).

1078.0 g of silica powder (a) are introduced into the tank of the Lodige granulator (peripheral speed of 1.96 meters). The stirring speed of the Lodige granulator is set at 150 rpm. The potentiometer of the pump is set to 5.

The slurry is then sprayed on the silica powder (a) for 4 minutes and 40 seconds; the spray pressure is 2 bar.

After stopping the pump at the end of the spraying, mixing is continued for another 15 minutes.

The product obtained is drained into a tank and then dried in an oven at 90-100 C for 48 hours.

The moisture of the dried product is 3.8%.

Granulometric analysis of the product obtained * sieving

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 Two sieves of opening 630um and 125um are weighed beforehand 100g of dry product are sieved with a sieve (Retsch type) for 5 minutes with an amplitude of 0.5.

The sieves are then weighed; the percentage of silica granules in each granulometric section is as follows:> 0.630 mm 27.8% [0.125 mm; 0.630mm] 51.9% <0.250mm 20.3% The cut [0.125mm; 0.630mm] is retained.

 * measure MALVERN particle size. cutting [0.125mm; 0.630mm]. dispersant: water. pump: 60%. agitation 60%. ultrasound 50% * moisture content The moisture content of the dried granules is measured on the section [0.125mm; 0.630mm] It is made with an Infra-Red scale.

The heater of the device is set at 160 C.

2 g of product are introduced into the apparatus. The appliance is switched on and off when the weight loss of the product no longer varies (approximately 15 minutes).

The product moisture determined by the apparatus is 3.8%.

* results

<Tb>
<tb> diameter <SEP> of <SEP> granules <SEP> without <SEP> ultrasound <SEP> after <SEP> 2 <SEP> minutes
<tb> in <SEP> m <SEP> ultrasound
<tb> in <SEP> m
<tb> D10 <SEP> 185.58 <SEP> 16.48
<tb> D50 <SEP> 404.27 <SEP> 251.10
<tb> D90 <SEP> 675.69 <SEP> 567.89
<Tb>
which corresponds to an FC cohesion factor of 0.62

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Examples 2 to 4 The granulation process described in Example 1 is carried out using a "slurry" of silica of different particle size.

<Tb>
<tb> diameter <SEP> of <SEP> example2 <SEP> example3 <SEP> example <SEP> 4
<tb>"slur<SEP> comparative
<tb> D10b <SEP> without <SEP> US <SEP> 3.24 <SEP> m <SEP> 0.32 <SEP> m <SEP> 8.21 <SEP> m
<tb> D10b <SEP> after <SEP> US <SEP> 3.09 <SEP> m <SEP> 0.31 <SEP> m <SEP> 8.04 <SEP> m
<tb> D50b <SEP> without <SEP> US <SEP> 18.51 <SEP> m <SEP> 4.25 <SE> pm <SEP> 35.50 <SE> pm <SEP>
<tb> D50b <SEP> after <SEP> US <SEP> 14.15 <SEP> m <SEP> 4.06 <SEP> m <SEP> 19.15 <SEP> m
<tb> D90b <SEP> without <SEP> US <SEP> 185.47 <SEP> m <SEP> 15.70 <SE> pm <SEP> 289.12 <SEP> m
<tb> D90b <SEP> after <SEP> US <SEP> 33.94 <SEP> m <SEP> 14.62 <SEP> m <SEP> 39.19 <SEP> m
<Tb>
The characteristics of the granules obtained are as follows

<Tb>
<tb> example <SEP> diameter <SEP> of <SEP> without <SEP> ultrasound <SEP> after <SEP> 2 <SEP> minutes <SEP> FC
<tb> granules <SEP> in <SEP> m <SEP> ultrasound
<tb> in <SEP> m
<tb> D10 <SEP> 185 <SEP> 10.9
<tb> 2 <SEP> D50 <SEP> 395.5 <SEP> 122.8 <SEP> 0.31
<tb> D90 <SEP> 664.7 <SEP> 364.8
<tb> D10 <SEP> 146.5 <SEP> 62.9
<tb> 3 <SEP> D50 <SEP> 356 <SEP> 309.9 <SEP> 0.87
<tb> D90 <SEP> 640.9 <SEP> 608.2
<tb> D10 <SEP> 162.7 <SEP> 7.9
<tb> 4 <SEP> comparative <SEP> D50 <SEP> 358 <SEP> 34.8 <SEP> 0.1
<tb> D90 <SEP> 639.3 <SEP> 99.3
<Tb>
Example 5 Equipment used * MOINEAU displacement pump * 20 liter LÖDIGE granulator * LECHLER pressure nozzle (Ref .: 460.403.17; 0 0.85 mm) * 8 liter glass feed tank with stirring

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* IR balance for dry tests (160 C) Products used * silica powder (a): Tixosil 38AB from Rhodia. particle size distribution (measured in MALVERN 100% US) without ultrasound after ultrasound
D10a 8.43um 7.52um
D50a 24.65um 18.72um
D90a 102.50um 66.25um. moisture = 10% * silica particles (b): Tixosil 43 silica powder from Rhodia. particle size distribution (measured in MALVERN 100% US) without ultrasound with ultrasound
D10b 6.53 m 5.4 m
D50b 14.31 m 10.9 m
D90b. 37.57 m 19.6 m. humidity = 9.4% Granulation 1078 g of silica powder (a) and 488 g of silica powder (b) are introduced into the granulator.

The stirring speed of the Lodige granulator is set at 200 rpm (peripheral speed of 2.6 m / s).

The powders are premixed for 10 minutes.

3132 g of water are introduced into the Lôdige's supply tank, which corresponds to a ratio (Rm) of the total quantity of water (WT) to the total quantity (ST) of silica, (Rm) = ( WT) / (ST), of 2.

The potentiometer of the pump is set to 5.

The water is then sprayed onto the silica powders mixture for 4 minutes 30 seconds; the spray pressure is less than 1 bar.

After stopping the pump at the end of the spraying, mixing (granulation time TG) is continued for 15 minutes.

The product obtained is emptied into a tank; its dry extract is 30% in weight. It is then dried in an oven at 90-100 C overnight.

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Particle size analysis of the product obtained * sieving> 0.630 mm 41.7% [0.125 mm; 0.630mm] 46.2% <0.250mm 12.1% The cut [0.125mm; 0.630mm] is retained.

* humidity: 1.8% * results

<Tb>
<tb> diameter <SEP> of <SEP> granules <SEP> without <SEP> ultrasound <SEP> after <SEP> 2 <SEP> minutes
<tb> in <SEP> m <SEP> ultrasound
<tb> in <SEP> m
<tb> D10 <SEP> 57.5 <SEP> 14.2
<tb> D50 <SEP> 169.6 <SEP> 87.9
<tb> D90 <SEP> 406.2 <SEP> 257.6
<Tb>
which corresponds to an FC cohesion factor of 0.52 Examples 6 and 7 The granulation operation of Example 5 is repeated with the following modifications:

<Tb>
<tb> example <SEP> diameter <SEP> without <SEP> ultrasound <SEP> 2 <SEP> minutes <SEP> FC
<tb><SEP> in <SEP> m <SEP> ultrasound
<tb> granules <SEP> in <SEP> m
<tb> 6 <SEP> D10 <SEP> 153.9 <SEP> 9.1
<tb> Rm <SEP> = <SEP> 1.9 <SEP> D50 <SEP> 376.2 <SEP> 42.4 <SEP> 0.11
<tb> TG <SEP> = <SEP> 15 <SEP> minutes <SEP> D90 <SEP> 659.6 <SEP> 242
<tb> 7 <SEP> D10 <SEP> 187.8 <SEP> 170
<tb> Rm <SEP> = <SEP> 2 <SEP> D50 <SEP> 354.8 <SEP> 332.1 <SEP> 0.94
<tb> TG <SEP> = <SEP> 20 <SEP> minutes <SEP> D90 <SEP> 619.5 <SE> 591
<Tb>
EXAMPLE 8 Dentifrice Formulation The granules prepared in Example 1 (FC = 0.62) or in Example 5 (FC = 0.52) can be used for the preparation of the following toothpaste formulation:

<Desc / Clms Page number 15>

<Tb>
<tb> Constituents <SEP>% <SEP> in <SEP> weight
<tb> Gum <SEP> Xanthan <SEP> Rhodicare <SEP> S <SEP> (*) <SEP> 0.7
<tb> Sorbitol <SEP> Neosorb <SEP> 70170 <SEP> (**) <SEP> 25
<tb> Glycerine <SEP> 15
<tb> Polyethylene <SEP> glycol <SEP> mass <SEP> 400g <SEP> (PEG400) <SEP> 3
<tb> Saccharinate <SEP> of <SEP> sodium <SEP> 0.2
<tb> Benzoate <SEP> of <SEP> sodium <SEP> 0.3
<tb> Monofluorophosphate <SEP> of <SEP> sodium <SEP> (MFP) <SEP> 0.76
<tb> H20 <SEP> 23.47
<tb> Silica <SEP> polishing <SEP> Tixosil <SEP> 73 <SEP> (*) <SEP> 13
<tb> Silica <SEP> thickening <SEP> Tixosil <SEP> 43 <SEP> (*) <SEP> 4
<tb> TiO2 <SEP> (anatase) <SEP> Kronos <SEP> 1171 <SEP> 0.2
<tb> Color <SEP> FDC <SEP> blue <SEP> dye <SEP> Nr <SEP> 1 <SEP> (0.12% <SEP> in <SEP> H20) <SEP> 1
<tb> Aroma <SEP>: <SEP> spearmint <SEP> (***) <SEP> 0. <SEP> 7
<tb> Granules <SEP> of <SEP> Example <SEP> 1 <SEP> or <SEP> 5 <SEP> 8
<tb><SEP> foaming agent <SEP>: <SEP> Sipon <SEP> LCS <SEP> 98 <SEP> (30% <SEP> in <SEP> water) <SEP> 4,67
<Tb>
(*) marketed by RHODIA (**) marketed by ROQUETTE FRERES (***) marketed by MANE The initial premix mixture of sorbitol, glycerine and PEG allows the dispersion of Xanthan gum. After solubilization in water, sodium saccharin, sodium benzoate and MFP are then introduced.

In the type of mixer GUEDU, then operates the dispersion of Tixosil 43, Tixosil 73, TiO2, dye and flavor, and that of silica granules. We end with the addition of the foaming agent under vacuum.

Claims (21)

1) Precipitation silica granules of high structure (thickening), having a median diameter of at least 100 m, preferably from 120 to 650 m, obtained by wet granulation of precipitation silica of high structure (thickening), drying and optionally sieving, said granules being characterized in that they have an FC cohesion factor of at least 0.3, preferably 0.4 to 1, and in that the granulation step is carried out in a weakly shearing granulation apparatus, using at least one high-silica precipitating silica powder (a) having a DOP of at least 230 ml / 100 g, preferably at least 290 ml / 100 g. a median diameter D50a of at least 14 m, preferably at least 14 to 50 m, most preferably 14 to 30 m * particles of at least one precipitating silica (b) having. a DOP of at least 230 ml / 100 g, preferably at least 290 ml / 100 g. a median diameter D50b of at least 0.3 μm and at most 13 μm, preferably 0.5 to 13 μm, and water (W) as binder the dry extract of the mixture formed by the silicas ( a) and (b) and the water (W) being 25 to 40% by weight, preferably 30 to 35% by weight, the weight ratio (a) / (b), expressed as dry, of the silica (a) silica (b) ranging from 1.5 to 6, preferably from 1.8 to 4, most preferably from 2 to 3.5.  2) Granules according to claim 1), characterized in that the median diameter D50b of the silica particles (b) is from 1 to 3 times, preferably from 1 to 2 times less than the median diameter D50a of the silica powder particles (a). ).  3) Granules according to claim 1) or 2), characterized in that the silica particles (b) are used in the form of dry powder.  4) Granules according to claim 1) or 2), characterized in that the silica particles (b) are implemented in the form of a suspension in water (W) and form a binding assembly (L).  5) Granules according to claim 4, characterized in that the binding assembly (L) is a binder assembly (L1) obtained by redispersion in water (W) of silica particles (b) in dry powder form. <Desc / Clms Page number 17>  6) Granules according to claim 4), characterized in that the binding assembly (L) is a binding assembly (L2) formed by the suspension of precipitated silica (b) directly from the synthesis by precipitation in an aqueous medium of the silica (b) and before drying of said silica 7) Granules according to any one of claims 1) to 6), characterized in that the granulation operation is carried out by spraying the water (W) or the binding assembly (L) on the powder or powders silica or contacting the water (W) or the binding assembly (L) and the silica powder or powders in the granulation apparatus.  8) Granules according to any one of claims 1) to 7), characterized in that the granulation apparatus comprising shearing means capable of developing a peripheral speed at the end of the rotor from 0.5 m.s to less than 4 ms  9) Granules according to any one of claims 1) to 8), characterized in that the granulation operation is carried out continuously or discontinuously.  10) Granules according to claim 9, characterized in that the granulation operation is carried out batchwise, the residence time of the raw materials in the granulator being from 15 to 45 minutes, the granulation time being from 10 to 20 minutes .  11) Granules according to any one of claims 1) to 10), characterized in that the amount of total water (WT) used in the granulation medium relative to the total amount (ST), expressed in dry, silica applied corresponds to a weight ratio (WT) / (ST) greater than 1.8 and less than 2.5.  12) Granules according to any one of claims 1) to 11), characterized in that the silica powder (a) has a diameter D10a of at least 1 m, preferably at least 3 m, and less than 10 m Granules according to one of claims 1 to 12, characterized

 in that silica particles (b) have a diameter Dlpb of at least 0.1 Nm and at most 7 m. <Desc / Clms Page number 18>  14) Granules according to Claim 13, characterized in that the silica (b) is in the form of a dry powder or of a dry powder which is redispersed in water, and presents

 a diameter DlOb of 3m to 7hum.  15) Granules according to claim 13, characterized in that the silica (b) is an undried silica suspension resulting directly from the synthesis by precipitation in an aqueous medium of the silica (b) before drying, having a diameter D10b less than 4 m.  16) Use of the granules according to any one of claims 1) to 15) as additives in the compositions for cleaning and / or treating the skin, teeth and other hard surfaces, at a rate of 0, 1 to 50% by weight of said compositions.  17) Use according to claim 16), as an exfoliating agent in the cosmetic compositions in a proportion of 0.5 to 5% of the weight of said compositions.  18) Use according to claim 16), as cleaning agent in the compositions for cleaning hard surfaces in a proportion of 20 to 50% of the weight of said compositions.  19) Granules according to any one of claims 1) to 15), characterized in that they present. a median diameter of at least 250 m, preferably 300 to 450 m, especially 300 to 400 m. and an FC cohesion factor of 0.45 to 0.75, most preferably 0.5 to 0.7.  20) Use of the granules as claimed in claim 19) as thickening agents with sensory effect in the mouth in dental compositions.  21) Dental compositions comprising from 0.1 to 12%, preferably from 0.5 to 10% by weight of the granules forming the subject of claim 19).