MAGNESIUM ION-CONTAINING MATERIALS AS WHITE PIGMENTS IN ORAL CARE COMPOSITIONS

Abstract

The present invention relates to an oral care composition comprising a magnesium ion-containing material in an amount from 0.1 to 40 wt.-%, based on the total weight of the composition as well as the use of a magnesium ion-containing material as opacifying agent and/or whitening pigment in oral care compositions.

Claims

1. An oral care composition comprising a magnesium ion-containing material in an amount from 0.1 to 40 wt.-%, based on the total weight of the composition, wherein the magnesium ion-containing material is in form of particles having a volume median grain diameter (d50) from 150 nm to 20 μm and is selected from the group consisting of anhydrous magnesium carbonate or magnesite (MgCO3), hydromagnesite (Mg5(CO3)4(OH)2.4H2O), artinite (Mg2(CO3)(OH)2.3H2O), dypingite (Mg5(CO3)4(OH)2.5H2O), giorgiosite (Mg5(CO3)4(OH)2.5H2O), pokrovskite (Mg2(CO3)(OH)2.0.5H2O), barringtonite (MgCO3.2H2O), lansfordite (MgCO3.5H2O), nesquehonite (MgCO3.3H2O), brucite (Mg(OH)2), dolomite (CaMg(CO3)2), dolocarbonate and mixtures thereof.

2. The oral care composition according to claim 1, wherein the magnesium ion-containing material is selected from anhydrous magnesium carbonate or magnesite (MgCO3), dolomite (CaMg(CO3)2), hydromagnesite (Mg5(CO3)4(OH)2.4H2O), brucite (Mg(OH)2) and mixtures thereof.

3. The oral care composition according to claim 1, wherein the magnesium ion-containing material is in form of particles having a) a volume median grain diameter (d50) from 0.2 to 15 μm, even more preferably from 0.5 to 10 μm, and most preferably from 1 to 5 μm, as determined by laser diffraction, and/or b) a volume determined top cut particle size (d98) of equal to or less than 30 μm, preferably from 2 to 30 μm, more preferably from 5 to 20, and most preferably from 8 to 18 μm, as determined by laser diffraction.

4. The oral care composition according to claim 1, wherein the magnesium ion-containing material has a whiteness determined as CIELAB L* of >90%, preferably >95%, more preferably >98% and most preferably >98.5% and measured dry according to EN ISO 11664 4:2010.

5. The oral care composition according to claim 1, wherein the magnesium ion-containing material is in form of particles having a BET specific surface area in the range from 2 to 200 m2/g, preferably from 10 to 100 m2/g, and most preferably from 12 to 75 m2/g, measured using nitrogen and the BET method according to ISO 9277:2010.

6. The oral care composition according to claim 1, wherein the oral care composition further comprises a fluoride compound, preferably the fluoride compound is selected from the group consisting of sodium fluoride, stannous fluoride, sodium monofluorophosphate, potassium fluoride, potassium stannous fluoride, sodium fluorostannate, stannous chlorofluoride, amine fluoride, and mixtures thereof, and more preferably the fluoride compound is sodium monofluorophosphate and/or sodium fluoride.

7. The oral care composition according to claim 1, wherein the oral care composition further comprises a remineralisation and/or whitening agent, preferably selected from the group consisting of silica, hydroxylapatite, e.g. nano-hydroxylapatite, calcium carbonate, e.g. amorphous calcium carbonate, ground calcium carbonate, precipitated calcium carbonate, surface-reacted calcium carbonate and combinations thereof, calcium silicate and mixtures thereof.

8. The oral care composition according to claim 1, wherein the oral care composition is a toothpaste, a toothgel, a toothpowder, a varnish, an adhesive gel, a cement, a resin, a spray, a foam, a balm, a composition carried out on a mouthstrip or a buccal adhesive patch, a chewable tablet, a chewable pastille, a chewable gum, a lozenge, a beverage, or a mouthwash, preferably a chewable gum, a lozenge, a toothpaste, a toothpowder, or a mouthwash, and most preferably a toothpaste.

9. The oral care composition according to claim 1, wherein the oral care composition has a pH between 6.8 and 10, preferably between 7.5 and 9 and most preferably between 8 and 9.

10. The oral care composition according to claim 1, wherein the oral care composition comprises the magnesium ion-containing material in an amount from 0.5 to 10 wt.-%, based on the total weight of the composition.

11. Use of a magnesium ion-containing material as opacifying agent and/or whitening pigment in oral care compositions, wherein the magnesium ion-containing material is in form of particles having a volume median grain diameter (d50) from 150 nm to 20 μm and is selected from the group consisting of anhydrous magnesium carbonate or magnesite (MgCO3), hydromagnesite (Mg5(CO3)4(OH)2.4H2O), artinite (Mg2(CO3)(OH)2.3H2O), dypingite (Mg5(CO3)4(OH)2.5H2O), giorgiosite (Mg5(CO3)4(OH)2.5H2O), pokrovskite (Mg2(CO3)(OH)2.0.5H2O), barringtonite (MgCO3.2H2O), lansfordite (MgCO3.5H2O), nesquehonite (MgCO3.3H2O), brucite (Mg(OH)2), dolomite (CaMg(CO3)2), dolocarbonate and mixtures thereof.

12. The use according to claim 11, wherein the magnesium ion-containing material is selected from anhydrous magnesium carbonate or magnesite (MgCO3), dolomite (CaMg(CO3)2), hydromagnesite (Mg5(CO3)4(OH)2.4H2O), brucite (Mg(OH)2) and mixtures thereof.

13. The use according to claim 11, wherein the magnesium ion-containing material is in form of particles having a) a volume median grain diameter (d50) from 0.2 to 15 μm, even more preferably from 0.5 to 10 μm, and most preferably from 1 to 5 μm, as determined by laser diffraction, and/or b) a volume determined top cut particle size (d98) of equal to or less than 30 μm, preferably from 2 to 30 μm, more preferably from 5 to 20, and most preferably from 8 to 18 μm, as determined by laser diffraction, and/or c) a BET specific surface area in the range from 2 to 200 m2/g, preferably from 10 to 100 m2/g, and most preferably from 12 to 75 m2/g, measured using nitrogen and the BET method according to ISO 9277:2010.

Description

EXAMPLES

1. Measurement Methods

[0094] In the following, measurement methods implemented in the examples are described.

Particle Size Distribution

[0095] Volume determined median particle size d.sub.50(vol) and the volume determined top cut particle size d.sub.98(vol) was evaluated using a Malvern Mastersizer 3000 Laser Diffraction System (Malvern Instruments Plc., Great Britain) equipped with a Hydro LV system. The d.sub.50(vol) or d.sub.98(vol) value indicates a diameter value such that 50% or 98% by volume, respectively, of the particles have a diameter of less than this value. The powders were suspended in 0.1 wt.-% Na.sub.4O.sub.7P.sub.2 solution. 10 mL of 0.1 wt.-% Na.sub.4O.sub.7P.sub.2 was added to the Hydro LV tank, then the sample slurry was introduced until an obscuration between 10-20% was achieved. Measurements were conducted with red and blue light for 10 s each. For the analysis of the raw data, the models for non-spherical particle sizes using Mie theory was utilized, and a particle refractive index of 1.57, a density of 2.70 g/cm.sup.3, and an absorption index of 0.005 was assumed. The methods and instruments are known to the skilled person and are commonly used to determine particle size distributions of fillers and pigments.

Specific Surface Area (SSA)

[0096] The specific surface area was measured via the BET method according to ISO 9277:2010 using nitrogen as adsorbing gas on a Micromeritics ASAP 2460 instrument from Micromeritics. The samples were pretreated in vacuum (10.sup.−5 bar) by heating at 150° C. for a period of 60 min prior to measurement.

CIELAB L* of Particulate Materials

[0097] The CIELAB L* of the magnesium ion-containing material and other particulate materials was measured dry in accordance with EN ISO 11664-4:2010.

Fluoride Availability

[0098] A toothpaste was freshly prepared as oral care composition and aged overnight (14 h) to establish short-term equilibration of the fluoride concentration (i.e. fluoride availability) for each composition. Extraction was conducted by diluting the toothpaste with the 10-fold equivalent of demineralized water (typically 3-5 g of toothpaste diluted with 30-50 g water) in a glass beaker, followed by vigorous stirring at 800 rpm for 1 h, and filtration through a syringe filter (Chromafil Xtra, RC-20/25 0.2 μm). Fluoride availabilities were determined after volumetric dilution (Eppendorf Research Plus micropipettes) by a factor of 100 using cuvette tests (Hach Lange LCK 323, Fluoride 0.1-2.5 ppm) in a Hach-Lange DR6000 spectrophotometer. The weighted-in quantities for all dilutions were recorded and the effective (free) fluoride concentrations (i.e. the fluoride availability) in the original formulations were calculated using these values. The percentage of extractable fluoride was reported with respect to a benchmark experiments with unmodified (base formulation) toothpaste, which were conducted for each series of experiments. The result attained with the unmodified toothpaste was multiplied by 0.98 to account for the dilution of the toothpaste by the addition of the corresponding particulate material (base material). Some samples were added as filter cakes with solids contents between 10-85 wt. %, the occurring dilution was accounted for in the calculation of the fluoride availability.

Whiteness/CIELAB L* of Oral Care Compositions

[0099] The corresponding toothpaste was transferred into a PTFE sample holder and subsequently covered with a glass plate to attain a reproducible, flat surface. The samples were evaluated in a Datacolor ELREPHO spectrophotometer using barium sulfate as reference material. The values reported for whiteness are the L* lightness values of the CIELAB color space according to EN ISO 11664-4:2010.

Opacity of Oral Care Compositions

[0100] The corresponding toothpaste was diluted with 15 wt. % of demineralized water and mixed on a speed mixer (Hauschild DAC 150.1 FVZ) for 20 s at 2760 rpm. Subsequently, a 300 μm layer was spread out on a Leneta Opacity Chart (Form 3B-H) using a TQC AFA Compact automatic film applicator with 23 mm s.sup.−1. The film was immediately covered with clear plastic sheets to prevent drying. The contrast value (R.sub.y, black/R.sub.y, white*100) was calculated based on the average of three separate measurements of R.sub.y per area in a Datacolor 800V spectrophotometer using barium sulfate as reference.

2. Materials Used

[0101] The particulate materials set out in table 1 have been used as base materials for the present invention.

TABLE-US-00001 TABLE 1 base materials Base material Name Description Supplier #M1 PHM 1 Precipitated Omya hydromagnesite (PHM) International #M2 PHM 2 PHM disagglomerated Omya platelets International #M3 PCC 1 Precipitated calcium Omya carbonate International #M4 GCC Ground calcium carbonate Omya International #M5 PCC 2 Precipitated calcium Omya carbonate International #M6 PCC 3 Precipitated calcium Omya carbonate International #M7 TiO.sub.2 Titanium dioxide Kronos #M8 MgCO.sub.3 1 Magnesium carbonate Sigma-Aldrich basic, heavy #M9 MgCO.sub.3 2 Magnesium carbonate Sigma-Aldrich basic, light #M10 MgCO.sub.3 4 Wet-Milled #M11, Omya very fine International #M11 MgCO.sub.3 5 Wet-milled #M11, Omya agglomerated International #M12 Dolomite 1 Micronized dolomite, Omya coarse International #M13 Dolomite 2 Wet-milled dolomite, Omya fine International #M14 Dolomite 3 Wet-ground dolomite, Omya very fine International #M15 Dolocarbonate Dolocarbonate composite Omya material International #M16 Mg(OH).sub.2 1 Precipitated magnesium Van Mannekus hydroxide #M17 Mg(OH).sub.2 2 Wet-milled #M21, Omya very fine International

[0102] The characteristics of the base materials are set out in the following table 2.

TABLE-US-00002 TABLE 2 characteristics of the particulate materials used as base materials S.sub.BET/ d.sub.50/ d.sub.98/ Base material m.sup.2 g.sup.−1 μm μm #M1 25 25 73 #M2 53 12 51 #M3 22 2.9 249 #M4 14 0.3 3.5 #M5 11 2.0 5.2 #M6 11 2.7 21 #M7 377 0.1 3.5 #M8 9.3 39 103 #M9 28 10 26 #M10 35 0.7 404 #M11 12 19 226 #M12 3.2 3.3 11 #M13 12 0.9 27 #M14 17 0.5 2.7 #M15 17 178 1250 #M16 4.8 2.1 6.2 #M17 35 0.3 6.1

[0103] For the preparation of a toothpaste base formulation, an IKA ULTRA TURRAX® disperser was used. The ingredients in the toothpaste base formulation are listed in the following table 3. The formulations were prepared with 1 kg total mass. In a beaker, sorbitol, sodium fluoride, sodium saccharin, sodium benzoate, propylene glycol and glycerin and cellulose gum were vigorously mixed. Subsequently, water was added and the mixture further agitated until a homogeneous texture was attained. Then, Sorbosil AC35 was added step-wise under strong agitation and further stirred until a homogeneous texture was attained. Then, Sorbosil TC15 was added step-wise under strong agitation and further stirred until a homogeneous texture was attained to obtain the toothpaste base formulation. Two master batches of toothpaste were prepared based on different batches of raw materials. To compensate for the occurring differences (particularly in the optical properties) they will be differentiated as batch 1 (#B1) and batch 2 (#B2).

TABLE-US-00003 TABLE 3 Recipe of the toothpaste base formulation. # Ingredient Quantity/mass equiv. I1 sorbitol 70% 23.67 I2 demineralized water 25.85 I3 Phoskadent NaF 0.34 I4 sodium saccharin 0.11 I5 sodium benzoate 0.11 I6 propylene glycol 10.76 I7 glycerol 10.76 I8 cellulose gum 0.86 I9 Sorbosil AC35 silica 21.52 I10 Sorbosil TC15 silica 6.02 I11 sodium lauryl sulfate (15 wt. % solution) 1.25 I12 aroma spearmint 0.80

[0104] The final toothpaste was prepared in a plastic container by adding the desired quantity of the corresponding base material (0.25-2 g) to 25-30 g of the toothpaste base formulation. The formulations were manually mixed using a spatula, and subsequently homogenized using either a speed mixer (Hauschild DAC 150.1 FVZ) for 20 sat 2760 rpm or a Polytron GT 10-35 PT disperser equipped with a PT-DA 30/2EC-F250 dispersing aggregate. Subsequently, the desired quantity of surfactant (I11 according to the base formulation recipe in table 3) was added using an Eppendorf Research Plus micropipette and the formulation were mixed manually using a spatula. Finally, the desired quantity of flavour (I12 according to the base formulation recipe in table 3) was added using an Eppendorf Research Plus micropipette and the formulation was mixed manually using a spatula.

3. Results

[0105] The toothpastes prepared were evaluated with respect to the fluoride availability, the whiteness and opacity. The results are set out in the following table 4.

TABLE-US-00004 TABLE 4 results Base Fluoride White- Base material avail- ness Opacity Base formu- quantity/ ability/ CIELAB Contrast material lation wt. % % L*/— value/—. — #B1 0 100 73.2 2.8 — #B2 0 100 79.3 2.7 #M1 #B1 1.94 81 83.5 5.2 #M1 #B1 2.94 — 82.1 7.3 #M1 #B1 3.80 — 82.3 9.4 #M1 #B1 5.82 — 85.1 12.6 #M1 #B2 1.87 82 84.1 4.7 #M2 #B2 1.98 89 80.8 4.9 #M3 (ref) #B1 2.03 46 85.5.sup.# 8.8.sup.# #M4 (ref) #B1 1.95 39 86.0 7.5 #M5 (ref) #B1 1.88 40 86.1.sup.# 7.8.sup.# #M6 (ref) #B1 1.92 43 86.0.sup.# 7.3.sup.# #M7 (ref) #B1 0.99 99 90.4 20.7 #M8 #B2 1.96 86 83.4 4.0 #M9 #B2 1.95 87 83.2 3.6 #M10* #B2 1.83 100 84.8 5.8 #M11* #B2 1.86 89 84.1 4.8 #M12 #B2 1.92 94 84.7 5.5 #M13* #B2 1.93 98 83.0.sup.# n/a.sup.# #M14* #B2 1.89 85 82.8.sup.# n/a.sup.# #M15 #B2 1.98 81 84.0 4.2 #M16 #B2 1.97 85 86.3 7.0 #M17* #B2 1.91 89 83.5 7.5 .sup.#agglomerates were present in the toothpaste and thus no optimal data for opacity and whiteness could be achieved, may be improved by thorough mixing; *Added as filter cake

[0106] From the results, it can be gathered that the surface-treated materials according to the present invention provide high fluoride availability in combination with high whiteness and opacity.