Dental-care composition

Claim 2

An opaque dental-care toothpaste composition having a smooth, speck free and glossy ribbon as well as improved shelf life in respect of rheology and abrasiveness, which comprises about 30 to 40% by weight of water, and as the essential thickener and abrasive, about 15 to 25% by weight of a precipitated silica characterized by the following physicochemical properties: ______________________________________ BET surface area determined m.sup.2 /g 15-110 according to DIN 66,131 Tamped density g/l 90-650 Secondary particle size according to FIG. 2 distribution curve accor- ding to Coulter Counter "ALPINE" screen in retainings % by <0.1 >63 μm weight Cu abrasion in 10% strength mg 5-30 glycerol dispersion Viscosity of a 30% strength mPa.s 30,000-60,000 dispersion in a 1:1 water/ glycerol mixture (Brookfield RTV Sp 5) Lightness value A % 90-96. according to DIN 55,921 ______________________________________

Claim 3

An opaque dental-care toothpaste composition having a smooth, speck free and glossy ribbon as well as improved shelf life in respect of rheology and abrasiveness, which comprises about 30 to 40% by weight of water and, as the essential thickener and abrasive, about 15 to 25% by weight of a precipitated silica characterized by the following physicochemical properties: ______________________________________ BET surface area determined m.sup.2 /g 15-110 according to DIN 66,131 Tamped density g/l 90-650 Secondary particle size according to FIG. 2 distribution curve according to Coulter Counter "ALPINE" screen retaining % by <0.1 >63 μm weight Cu abrasion in 10% strength mg 5-30 glycerol dispersion Viscosity of a 30% strength mPa.s 30,000-60,000 dispersion in a 1:1 water/ glycerol mixture (Brookfield RTV Sp 5) Lightness value A according to % 90-96 DIN 55,921 ______________________________________ wherein said precipitated silica is prepared by providing an initial alkali metal silicate solution having a concentration of about 5-25 g of SiO 2 per liter of solution and adding thereto an acid and alkali metal silicate solution while maintaining a precipitation temperature in the reaction medium between 80° and 90° C., the precipitation being carried out under such conditions that the pH is kept between 10 and 12, the viscosity of the reaction medium being at a uniform low value for at least 30% of the total precipitation time, and terminating the addition of the reactants when the viscosity of the reaction medium, after passing through a maximum, falls to a value which is less than 100% above the initial value to thereby obtain a silica suspension, thereafter diluting the suspension of precipitated silica with hot water to form a precipitated silica content of 10-30 g/l and a sodium sulfate content of 6 to 20 g/l, heating to a temperature of 85°-95°, acidifying with the addition of sulfuric acid to a pH value of 7 to 9, and while keeping the pH value constant, adding alkali metal silicate solution, sulfuric acid and hot water simultaneously over a precipitation period of 30-180 minutes to provide a final concentration of precipitated silica of 40-80 g/l, acidifying the suspension with concentrated sulfuric acid to a pH below 7, thereafter separating the precipitated silica from the suspension by a filter press, washing, drying and milling with a jet mill.

Claim 4

An opaque dental-care toothpaste composition having a smooth, speck free and glossy ribbon as well as improved shelf life in respect of rheology and abrasiveness, which comprises about 30 to 40% by weight of water and, as the essential thickener and abrasive, about 15 to 25% by weight of a precipitated silica characterized by the following physicochemical properties: ______________________________________ BET surface area determined m.sup.2 /g 15-110 according to DIN 66,131 Tamped density g/l 90-650 Secondary particle size according to FIG. 2 distribution curve according to Coulter Counter "ALPINE" screen retaining % by <0.1 >63 μm weight Cu abrasion in 10% strength mg 5-30 glycerol dispersion Viscosity of a 30% strength mPa.s 30,000-60,000 dispersion in a 1:1 water/ glycerol mixture (Brookfield RTV Sp 5) Lightness value A according to % 90-96 DIN 55,921 ______________________________________ wherein said precipitated silica is prepared by providing an initial alkali metal silicate solution having a concentration of about 5-25 g of SiO 2 per liter of solution and adding thereto an acid and alkali metal silicate solution while maintaining a precipitation temperature in the reaction medium between 80° and 90° C., the precipitation being carried out under such conditions that the pH is kept between 10 and 12, the viscosity of the reaction medium being at a uniform low value for at least 30% of the total precipitation time, and terminating the addition of the reactants when the viscosity of the reaction medium, after passing through a maximum, falls to a value which is less than 100% above the initial value to thereby obtain a silica suspension, thereafter diluting the suspension of precipitated silica with hot water to form a precipitated silica content of 10-30 g/l and a sodium sulfate content of 6 to 20 g/l, heating to a temperature of 85°-95°, acidifying with the addition of sulfuric acid to a pH value of 7 to 9, and while keeping the pH value constant, adding alkali metal silicate solution, sulfuric acid and hot water simultaneously over a precipitation period of 30-180 minutes to provide a final concentration of precipitated silica of 40-80 g/l, acidifying the suspension with concentrated sulfuric acid to a pH below 7, thereafter separating the precipitated silica from the suspension by a filter press, washing, drying and milling with a jet mill.

Claim 5

The opaque dental-care composition according to claim 1 which further contains sorbitol.

Claim 6

The opaque dental-care composition according to claim 1 which additionally contains at least one of the group consisting of a chalk, aluminum hydroxide and calcium phosphate.

Claim 7

The opaque dental-care composition according to claim 1 which additionally contains at least one member from the group selected of a binder, a preservative, a sweetener, and an opacifier, a fluoride, a foaming agent and a dye.

Claim 8

The opaque dental-care composition according to claim 1 which further contains carboxymethyl-cellulose, the sodium salt of methyl p-hydroxybenzoate, saccharin, sorbitol, titanium dioxide opacifier, liquid paraffin, an aromatic oil and sodium lauryl sulfonate.

Claim 9

The opaque dental-care composition according to claim 1 for smokers wherein the precipitated silica having the following characteristics: ______________________________________ BET surface area determined m.sup.2 /g 15-110 according to DIN 66,131 Tamped density g/l 90-650 Secondary particle size according to FIG. 2 distribution curve according to Coulter counter "ALPINE" screen retainings % by <0.1 >63 μm weight Cu abrasion in 10% strength mg 16-18 glycerol dispersion Viscosity of a 30% strength mPa.s 30,000-60,000 dispersion in a 1:1 water/ glycerol mixture (Brookfield RTV Sp 5) ______________________________________