WO2021069256A1 - Silice pour compositions de soins buccaux - Google Patents

Silice pour compositions de soins buccaux Download PDF

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Publication number
WO2021069256A1
WO2021069256A1 PCT/EP2020/077218 EP2020077218W WO2021069256A1 WO 2021069256 A1 WO2021069256 A1 WO 2021069256A1 EP 2020077218 W EP2020077218 W EP 2020077218W WO 2021069256 A1 WO2021069256 A1 WO 2021069256A1
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Prior art keywords
silicate
precipitated silica
silica
anyone
acid
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PCT/EP2020/077218
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English (en)
Inventor
Jules VALENTE
Cédric FERAL-MARTIN
Caroline FAYOLLE
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Rhodia Operations
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Publication of WO2021069256A1 publication Critical patent/WO2021069256A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
    • A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K8/00—Cosmetics or similar toiletry preparations
    • A61K8/02—Cosmetics or similar toiletry preparations characterised by special physical form
    • A61K8/0241—Containing particulates characterized by their shape and/or structure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K8/00—Cosmetics or similar toiletry preparations
    • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
    • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
    • A61K8/20—Halogens; Compounds thereof
    • A61K8/21—Fluorides; Derivatives thereof
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K8/00—Cosmetics or similar toiletry preparations
    • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
    • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
    • A61K8/25—Silicon; Compounds thereof
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K8/00—Cosmetics or similar toiletry preparations
    • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
    • A61K8/30—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds
    • A61K8/33—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds containing oxygen
    • A61K8/36—Carboxylic acids; Salts or anhydrides thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/152—Preparation of hydrogels
    • C01B33/154—Preparation of hydrogels by acidic treatment of aqueous silicate solutions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • C01B33/187—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates
    • C01B33/193—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates of aqueous solutions of silicates
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
    • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
    • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
    • A61K2800/60—Particulates further characterized by their structure or composition

Definitions

  • the present invention relates to a precipitated silica for use in oral care compositions.
  • the invention relates to a precipitated silica having a good compromise between thickening and abrasive properties as well as good compatibility with therapeutic agents such as stannous fluoride and zinc.
  • Oral care products such as toothpastes can provide both therapeutic and cosmetic hygiene benefits.
  • Therapeutic benefits include caries prevention which is typically provided by the use of various fluoride salts; gingivitis prevention by the use of antimicrobial agents; or hypersensitivity control.
  • Cosmetic benefits provided by oral products include the control of plaque and calculus formation, removal and prevention of tooth stain, tooth whitening, breath freshening, and overall improvements in mouth feel impression.
  • fluoride One differentiating factor among oral care products, such as toothpaste, is the active ingredient, fluoride.
  • fluoride sources are typically sodium fluoride, sodium monofluorophosphate, and stannous fluoride.
  • Sodium fluoride and sodium monofluorophosphate are effective sources of fluoride ions that remineralize and strengthen weakened enamel thus allowing fighting cavities.
  • stannous fluoride not only delivers cavity fighting fluoride, but it also has antibacterial properties, and it provides an anti-sensitivity mechanism of action.
  • Stannous fluoride has both bactericidal and bacteriostatic properties, which fight plaque and gingivitis.
  • Stannous fluoride also deposits a protective mineral barrier over exposed dentinal tubules to help prevent sensitivity pain from triggers such as hot or cold liquids and foods.
  • Toothpaste compositions commonly contain so-called thickening silica for controlling the rheology of the toothpaste composition.
  • Silica is known to interact with other co-ingredients of the compositions such as fluorides and zinc compounds. Silica is also not adequately compatible with tin, strontium and other metallic cations. Such incompatibilities have the consequence that these ingredients are no longer available to elicit their beneficial effects.
  • EP396460A1 discloses precipitated silica, suitable either as abrasive or as thickening agent, having good compatibility with metallic cations, in particular Zn, as well as with the fluoride ion.
  • thickening silicas prepared according to EP396460A1 do not possess an optimal balance of properties like thickening ability and low abrasion on one end and good compatibility to ions such as zinc and tin.
  • Objective of the present invention is to provide a silica that has improved compatibility with the active ingredients of the toothpaste composition and that is, at the same time, an effective rheology control agent for the composition.
  • Object of the invention is a precipitated silica which is characterised by: a CTAB surface area SCTAB of at least 80 m 2 /g; a volume of the pores having a diameter of 1 pm or less of at least 1.90 ml_/g; and a stannous ion compatibility equal to or greater than 40%.
  • the CTAB surface area SCTAB is a measure of the external specific surface area as determined by measuring the quantity of N hexadecyl-N,N,N- trimethylammonium bromide adsorbed on the silica surface at a given pH.
  • the CTAB surface area SCTAB is at least 85 m 2 /g, typically at least 90 m 2 /g.
  • the CTAB surface area does not exceed 190 m 2 /g.
  • the CTAB surface area SCTAB may be lower than 185 m 2 /g, preferably lower than 180 m 2 /g.
  • CTAB surface area SCTAB are from 85 to 180 m 2 /g, preferably from 90 to 170 m 2 /g.
  • the BET surface area SBET of the inventive silica is not particularly limited, but it is at least 85 m 2 /g, typically at least 90 m 2 /g. BET surface area SBET is generally at most 200 m 2 /g. The BET surface area may advantageously be from 85 to 190 m 2 /g, even from 90 to 185 m 2 /g, preferably from 95 to 180 m 2 /g.
  • volume generated by the pores of the inventive silica is measured by mercury porosimetry as described in detail hereafter.
  • the volume of the pores having a diameter of 1 pm or less, hereinafter referred to as volume “Vi “, is at least 1.95 ml_/g, even at least 2.00 mL/g. Volume Vi is at most
  • Volume V 1 may conveniently be from 1.90 to 4.00 mL/g, even from 1.95 to
  • the inventive silica is advantageously characterised by a compatibility with stannous ions, as determined using the stannous ion compatibility method described hereafter, equal to or greater than 40%.
  • Stannous ions are generally Sn(ll) ions deriving from SnF2 .
  • the stannous ion compatibility may advantageously be 100%, even up to 80%.
  • the inventive silica has a stannous ion compatibility greater than 40% and up to 80%, even greater than 40% and up to 75%.
  • the inventive silica has a compatibility with zinc, as determined using the Zn compatibility method described hereafter, greater than 70%, even at least 75%.
  • the inventive silica exhibits in general a high compatibility with respect to other cations which are customarily present in toothpaste compositions.
  • cations are for instance, calcium, strontium, barium, manganese, indium, nickel, titanium, zirconium, silver, palladium, ammonium or amino cations.
  • These cations may be in the form of mineral salts, for example chloride, fluoride, nitrate, phosphate, sulfate or in the form of organic salts such as acetates, citrates.
  • the inventive silica is also provided with good compatibility towards the fluoride ion.
  • fluoride ion-yielding materials can be employed as sources of soluble fluoride in toothpaste compositions.
  • suitable fluoride ion-yielding materials include, for instance, sodium fluoride, (NaF), stannous fluoride (SnF2), potassium fluoride, (KF), potassium stannous fluoride (SnF2-KF), indium fluoride (lnF3), zinc fluoride (ZnF2), ammonium fluoride (NFUF), and stannous chlorofluoride (SnCIF).
  • the fluoride ion compatibility of the inventive silica is typically greater than 80%, preferably equal to or greater than 90%.
  • the inventive silica is characterised by a number of OFI groups per surface area, expressed as mmol of OFI/g of silica, which is less than 3.2, even less than 3.0 mmol of OFI/g of silica, preferably less than 2.8 mmol of OFI/g of silica.
  • the number of OFI groups per surface area typically is not less than 1.0 mmol of OFI/g of silica.
  • the inventive silica is further characterised by an oil absorption, measured as bis(2-ethylhexyl)adipate (DOA) absorption, which is between 200 and 400 mL/100 g, typically between 220 and 380 mL/100 g, preferably between 240 and 350 ml_/100g, even between 250 and 350 ml_/100g.
  • DOA bis(2-ethylhexyl)adipate
  • the inventive silica is characterised by a high thickening capacity when tested in standard toothpaste applications. Toothpaste Brookfield viscosity measured after 50 days at 20°C is typically above lOOPa.s.
  • the precipitated silica of the invention does not possess abrasive properties.
  • the inventive silica is characterised by an abrasion depth value, Flm, as determined using the PMMA abrasion test described hereafter, of less than 3.5 miti, preferably less than 3.0 pm.
  • the abrasion depth value, Hm is typically from 0.1 to less than 3.5 pm.
  • a second object of the present invention is a process for the preparation of a precipitated silica having high stannous ion compatibility and good rheology control abilities.
  • Said process comprises the general steps of a precipitation reaction between a silicate and an acid whereby a silica suspension is obtained, followed by the separation of a wet precipitated silica and the drying of the wet precipitated silica.
  • the process comprises the steps of:
  • step (vi) The silica suspension obtained at the end of step (vi) is generally submitted to a liquid/solid separation step to provide a filter cake.
  • the wet precipitated silica thus obtained is subsequently dried.
  • silicate is used herein to refer to one or more than one silicate which can be added during the course of the inventive process.
  • the silicate is typically selected from the group consisting of the alkali metal silicates.
  • the silicate is advantageously selected from the group consisting of sodium and potassium silicate.
  • Si0 2 /Na 2 0 weight ratio of from 2.0 to 4.0, in particular from 2.4 to 3.9, for example from 3.1 to 3.8.
  • the silicate may have a concentration of from 3.9 wt% to 25.0 wt%, for example from 5.6 wt% to 23.0 wt%, in particular from 5.6 wt% to 20.7 wt%.
  • the silicate concentration is expressed in terms of % by weight of S1O2.
  • the term “acid” is used herein to refer to one or more than one acid which can be added during the course of the inventive process. Any acid may be used in the process. Use is generally made of a mineral acid, such as sulfuric acid, nitric acid, phosphoric acid or hydrochloric acid, or of an organic acid, such as carboxylic acids, e.g. acetic acid, formic acid or carbonic acid.
  • a mineral acid such as sulfuric acid, nitric acid, phosphoric acid or hydrochloric acid
  • an organic acid such as carboxylic acids, e.g. acetic acid, formic acid or carbonic acid.
  • the acid may be metered into the reaction medium in diluted or concentrated form.
  • the same acid at different concentrations may be used in different stages of the process.
  • the acid is sulfuric acid.
  • sulfuric acid and sodium silicate are used in all of the stages of the process.
  • the same sodium silicate that is sodium silicate having the same concentration expressed as S1O2 is used in all of the stages of the process.
  • an aqueous silicate solution having a pH from 8.0 to 10.0 is provided in the reaction vessel.
  • the starting solution is an aqueous solution, the term “aqueous” indicating that the solvent is water.
  • the starting solution has a pH from 8.5 to 10.0. The pH is measured at the temperature of the reaction.
  • the concentration of the aqueous silicate solution provided in the reaction vessel in step (i) is less than 15 g/L.
  • the silicate concentration is typically less than 12 g/L, preferably less than 10 g/L.
  • the silicate concentration is at least 1 g/L.
  • the starting aqueous silicate solution may be obtained in different manners. In a first embodiment the starting aqueous silicate solution is obtained by adding an acid to a sodium silicate solution so as to obtain a pH value from 8.0 to 10.0.
  • the starting aqueous silicate solution may be obtained by simultaneously adding an acid and a silicate to water or an initial silicate solution in such a way that the desired pH and initial silicate concentration are achieved.
  • step (ii) of the process leads to a drop in the pH of the reaction medium.
  • the pH at the end of step (ii) is lower than the pH of the initial silicate solution.
  • Addition of the acid is carried out until a value of the pH of the reaction medium between 6.0 and 9.0, for example between 7.0 and 8.5, even between 7.0 and 8.0, is reached.
  • the temperature of the reaction medium during step (i) and (ii) of the process is typically between 70 and 97°C, typically between 80 and 95°C.
  • the rates of addition of the acid and of the silicate during step (iii) are controlled in such a way that the pH of the reaction medium is maintained in the range from 6.0 to 9.0.
  • the pH of the reaction medium is preferably maintained in the range from 7.0 to 8.5, more preferably from 7.0 to 8.0.
  • step (iii) is advantageously performed in such a manner that the pH value of the reaction medium is always equal (to within ⁇ 0.2 pH units) to the pH reached at the end of step (ii).
  • step (iii) the simultaneous addition of acid and silicate is continued, however the flow rates of either the silicate or the acid are modified in such a way that the pH of the reaction medium is lowered to a value of less than 7.0, preferably between 5.5 and 7.0 and, even more preferably, between 6.0 and 7.0 (step (iv)).
  • the flow rate of the acid is increased with respect to the flow rate in step (iii) while the flow rate of the silicate is maintained as during step (iii).
  • the flow rate of the silicate can be decreased while maintaining the flow rate of the acid constant.
  • step (iv) The pH at the end of step (iv) is lower than the pH of the reaction medium in step (iii).
  • step (v) a further simultaneous addition of acid and silicate is made to the reaction medium in step (v).
  • the rates of addition of the acid and of the silicate during step (v) are controlled in such a way that the pH of the reaction medium is maintained in the range from 5.0 to 7.0.
  • the pH of the reaction medium is preferably maintained in the range from 5.5 and 7.0 and, more preferably, between 6.0 and 7.0.
  • the value of the pH in step (v) is the same as the value at the end of step (iv).
  • step (v) an acid is added to the reaction medium to lower the pH to a value of less than 5.0, preferably between 3.0 and 5.0 (step (vi)) to obtain a suspension of precipitated silica.
  • a maturing step may optionally be performed between step (v) and step (vi).
  • the maturing step typically lasts 1 to 120 minutes, preferably 1 to 60 minutes.
  • a liquid/solid separation step is subsequently carried out on the suspension of precipitated silica.
  • the separation step normally comprises a filtration, followed, if necessary, by a washing operation.
  • the filtration is performed according to any suitable method, for example by means of a belt filter, a rotary filter, for example a vacuum filter, or, preferably a filter press.
  • the washing is typically carried out with water and/or with an aqueous acidic solution having a pH of between 2.0 and 7.0. Depending on the case, one or more washing steps may be carried out.
  • the filter cake may optionally be subjected to a liquefaction operation.
  • liquefaction is intended herein to indicate a process wherein a solid, namely the filter cake, is converted into a fluid-like mass.
  • the expressions “liquefaction step”, “liquefaction operation” or “disintegration” are interchangeably intended to denote a process wherein the filter cake is transformed into a flowable suspension, which can then be easily dried. After the liquefaction step the filter cake is in a flowable, fluid-like form and the precipitated silica is again in suspension.
  • an aqueous solution containing salts of metallic cations is added to the precipitated silica.
  • suitable metallic cations are for instance selected from the group consisitng of the divalent and/or tetravalent cations of Ti, Sn, Zr, Mg, Ca, Sr, Zn, Ba.
  • the cations are preferably selected from the group consisting of the divalent cations of Zn and Sn.
  • Suitable salts for the preparation of the solutions are for instance sulfates.
  • concentration of the metallic cation in the solution is at least 0.1 wt%, even at least 0.5 wt%. The cation concentration generally does not exceed 2.0 wt%.
  • the precipitated silica suspension obtained at the end of the liquefaction step is typically dried. Drying may be carried out using any means known in the art. Preferably, drying is carried out by spray drying. For this purpose, any suitable type of spray dryer may be used, especially a turbine spray dryer or a nozzle spray dryer (liquid-pressure or two-fluid nozzle). In general, when the filtration is carried out by means of a filter press, a nozzle spray dryer is used, and when the filtration is carried out by means of a vacuum filter, a turbine spray dryer is used.
  • the precipitated silica is usually in the form of approximately spherical beads.
  • the precipitated silica that can then be obtained is generally in the form of a powder.
  • the invention also relates to oral care compositions, preferably toothpaste compositions, containing the inventive precipitated silica.
  • suitable oral care compositions are for instance those described in US5578293, US5004597, US5225177.
  • Toothpaste compositions comprising the inventive silica have a good balance between good compatibility to cations, notably Sn(ll) and Zn(ll), to fluoride ions as well as high thickening capability and low abrasion.
  • CTAB surface area (SCTAB) values were determined according to an internal method derived from standard NF ISO 5794-1 , Appendix G.
  • BET surface area SBET was determined according to the Brunauer -
  • Emmett - Teller method as detailed in standard NF ISO 5794-1 , Appendix E (June 2010) with the following adjustments: the sample was pre-dried at 200°C ⁇ 10°C; the partial pressure used for the measurement P/P° was between 0.05 and 0.3.
  • Abrasivity of silica was determined according to an internal method using poly(methyl methacrylate) (PMMA) plates as a substrate.
  • PMMA poly(methyl methacrylate)
  • Cast PMMA plates Altuglas CN, Atoglas, Shore D hardness 60-70
  • 89 x 20 x 7.5 mm were used as substrate.
  • On each plate a 3 mm wide zone for brushing (Testing area) was defined using adhesive tape and then submitted to brushing for 10000 cycles using toothbrushes Brasserie Frangaise, held at 15° angle and under a 240 g load, in the presence of slurries of abrasive silica prepared according to IS011609:2010 protocol.
  • the abrasion depth (Hm, expressed in pm) at the end of the brushing cycles was measured across a 20 x 10 mm area including the Testing area by optical profilometry (Altimet Altisurf 500) on rinsed plates. The area around the Testing area was used to define the baseline for the optical profilometry determination.
  • Thickening capability of silicas was determined by measuring Brookfield viscosity of toothpaste formulations at 20°C after 50 days +/-1day ageing at 40°C in a climatic chamber, using Brookfield DVII+PRO rheometer and a spindle at 5 rpm.
  • Toothpaste formulations described in Table 1 were prepared in a GUEDU reactor (4.5 L) according to the protocol detailed Table 1 below. Silicas from the inventions were used in the formulation in an amount of 8 wt%. Pre-gel was prepared in a RAYNERI mixer, adding ingredients at 1000- 1500 rpm, the day before mixing on the GUEDU reactor.
  • a solution in sodium gluconate was prepared containing 0.45 wt % of SnF2 and from 0.6 to 1.0 wt %of sodium gluconate in a solvent composed of a mix of water and sorbitol (the amount of sorbitol in at most 70%). The amount of sorbitol and sodium gluconate were adjusted to prevent precipitation of stannous hydroxide.
  • the amount of fluoride ions in solution was determined using a fluoride ion selective electrode (Perfection or equivalent).
  • the amount of fluoride ions was determined by means of the software LabX. A calibration curve was done by measuring the potential of two standard solutions (190 ppm and 1900 ppm).
  • an initial solution containing NaF was prepared in a polypropylene vial of 1000 mL by adding 19.3 g ( ⁇ 0.1) of NaFhPC ⁇ , 51.1 g ( ⁇ 0.1) of Na2HP04 and 90 mL of a solution of NaF at 40 g/L and then bringing the volume of the solution to 1000 mL with distilled water.
  • the initial solution has a fluoride ion concentration of 1628 ppm and 0.5 M phosphate buffer.
  • the fluoride ion compatibility was calculated as the ratio of fluoride ions available in the solution after contact with silica (supernatant of step (3)) with respect to the theoretical value according to the following formula:
  • Oil absorption was determined using a method based on ASTM D 2414 for carbon black modified for precipitated silica. 12.5 g (+/- 0,1 g) of precipitated silica are added to the kneading chamber (Brabender Absorptometer “C”) with help to the spatula. Bis(2-ethylhexyl) adipate (DOA, CAS [103-23-]) 12.5 g (+/- 0.1 g) is added dropwise with a dosing rate of 4 mL/min at room temperature into the mixture with continuous mixing (rotation rate of kneader blades 125 rpm).
  • the DOA absorption capacity (in ml_/100g) of the silica is defined as : 100
  • Vzo % is the added volume of DOA when the torque value reaches 70% of the maximum value of the fitted polynomial curve and m S iiica is the introduced mass of silica (typically, 12.50 g).
  • silanol ratio (mmol/g) is defined by:
  • the suspension was filtered and washed on a filter press.
  • the filter cake thus obtained was disintegrated mechanically while adding deionized water in order to reach a silica concentration of 15 wt% in the mixture.
  • the pH of the resulting silica suspension was brought to 6.2 by the addition of 7.7 wt% sulfuric acid solution.
  • sodium silicate flow rate was kept constant at 50.2 g/min while the 7.7 wt% sulfuric acid solution flow rate was regulated to maintain the pH of the reaction medium at a value of 6.5.
  • the pH of the reaction medium was brought to a value of 3.4 with 7.7 wt% sulfuric acid at a flowrate of 54.7 g/min.
  • the reaction mixture was allowed to stand for 5 minutes. A suspension of precipitated silica was obtained.
  • the suspension was filtered and washed on a filter press.
  • the filter cake thus obtained was disintegrated mechanically while adding deionized water in order to reach a silica concentration of 15 wt% in the mixture.
  • the pH of the resulting silica suspension was brought to 6.2 by the addition of 7.7 wt% sulfuric acid solution.
  • the resulting suspension was dried by means of a nozzle spray dryer to obtain precipitated silica S2.
  • the properties of precipitated silica S2 are reported in Table 2.
  • Silica CS1 is Tixosil® 43, commercially available from Solvay.
  • Silica CS2 was prepared by following the procedure of Example 2 in EP396460A1 adapted to fit a 170L stainless steel reactor.
  • Silica S2 in addition to a high compatibility with both Sn(ll) and Zn(ll) cations has higher thickening ability combined with low abrasive characteristics than silica CS2, which is an advantage for silicas used for thickening purposes.
  • inventive silicas present a higher thickening ability and an enhanced compatibility to actives (Zn and Sn) with respect to both silica CS1 and CS2, as well as very low abrasion ability.

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Abstract

Une silice précipitée présente un bon équilibre entre l'aptitude à l'épaississement, de faibles propriétés d'abrasion et une compatibilité élevée avec les ions stanneux et zinc.
PCT/EP2020/077218 2019-10-07 2020-09-29 Silice pour compositions de soins buccaux WO2021069256A1 (fr)

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EP19306296.5 2019-10-07
EP19306296 2019-10-07

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Citations (10)

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EP0143848A1 (fr) * 1983-03-04 1985-06-12 Taki Chemical Co., Ltd. Base de silice pour dentifrice et son procede de preparation
EP0396460A1 (fr) 1989-05-03 1990-11-07 Rhone-Poulenc Chimie Silice pour compositions dentifrices compatible, notamment avec les cations métalliques
EP0407262A1 (fr) * 1989-07-03 1991-01-09 Rhone-Poulenc Chimie Silice à porosité controlée et son procédé d'obtention
US5004597A (en) 1987-09-14 1991-04-02 The Procter & Gamble Company Oral compositions comprising stannous flouride and stannous gluconate
US5225177A (en) 1990-01-19 1993-07-06 J. M. Huber Corporation Dentifrice abrasives and compositions
US5578293A (en) 1994-12-06 1996-11-26 Colgate Palmolive Company Oral compositions containing stabilized stannous compounds having antiplaque and antitartar efficacy
US6335396B1 (en) * 1993-09-29 2002-01-01 Rhodia Chimie Precipitated silica
EP2349488B1 (fr) 2008-11-25 2015-10-28 The Procter and Gamble Company Compositions de soin buccal contenant de la silice fondue
US20180168958A1 (en) * 2016-12-19 2018-06-21 The Procter & Gamble Company Dentifice Compositions Containing Stannous Compatible Silica Particles
WO2018114280A1 (fr) 2016-12-19 2018-06-28 Evonik Degussa Gmbh Silice compatible avec l'étain

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