Powder oral hygiene compositions and methods for their manufacture

Abstract

The invention provides a powder oral hygiene composition comprising xylitol, a source of carbon dioxide, an acid and an absorbent, wherein the composition has a water surface area greater than 160 m.sup.2/g.

Claims

1. A powder oral hygiene composition comprising: xylitol, a source of carbon dioxide, an acid, and an absorbent, wherein the xylitol is from 80 wt % to 95 wt % of the composition; wherein the composition has a water surface area greater than 160 m.sup.2/g; and wherein the composition can pass through a 250 micron sieve.

2. A composition according to claim 1, wherein the carbon dioxide source is from 3 wt % to 20 wt % of the composition.

3. A composition according to claim 1, wherein the absorbent is from 0.5 wt % to 20 wt % of the composition.

4. A composition according to claim 1, wherein the acid is from 0.5 wt % to 15 wt % of the composition.

5. A composition according to claim 1, comprising from about 3 wt % to about 20 wt % of a carbon dioxide source, from about 0.5 wt % to about 20 wt % of an absorbent and from 0.5 wt % to about 15 wt % of an acid.

6. A composition according to claim 1, wherein the carbon dioxide source is sodium bicarbonate.

7. A composition according to claim 1, wherein the absorbent is silica dioxide.

8. A composition according to claim 1, wherein the acid is citric acid.

9. A composition according to claim 1, comprising from about 3 wt % to about 20 wt % of a carbon dioxide source, wherein the carbon dioxide source is sodium bicarbonate.

10. A composition according to claim 1, comprising from about 0.5 wt % to about 20 wt % of an absorbent, wherein the absorbent is silica dioxide.

11. A composition according to claim 1, comprising from about 0.5 wt % to about 15 wt % of an acid, wherein the acid is citric acid.

12. A composition according to claim 1, comprising from about 3 wt % to about 20 wt % of a carbon dioxide source.

13. A composition according to claim 1, comprising from about 3 wt % to about 20 wt % of a carbon dioxide source and from about 0.5 wt % to about 15 wt % of an acid.

14. A composition according to claim 1, comprising from about 3 wt % to about 20 wt % of a carbon dioxide source, from about 0.5 wt % to about 20 wt % of an absorbent and from 0.5 wt % to about 15 wt % of an acid.

15. A composition according to claim 1, comprising from about 3 wt % to about 20 wt % of a carbon dioxide source, from about 0.5 wt % to about 20 wt % of an absorbent and from 0.5 wt % to about 15 wt % of an acid, wherein the carbon dioxide source is sodium bicarbonate, the absorbent is silica dioxide and the acid is citric acid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a GVS isotherm of a prior art composition similar to that described in US 2015/0004560, for convenience referred to as WOW Pink

(2) FIG. 2 is a GVS isotherm of a composition according to the invention, as described in the Example, for convenience referred to as SWISH

(3) FIG. 3 is a BET plot for WOW Pink based on the GVS data in FIG. 1

(4) FIG. 4 is a BET plot for SWISH based on the GVS data in FIG. 2

(5) FIG. 5 is a scanning electron micrograph of WOW Pink

(6) FIG. 6 is a scanning electron micrograph of SWISH

EXAMPLES

(7) Preparation of a Powder Oral Hygiene Composition According to the Invention.

(8) A powder oral hygiene composition according to the invention was prepared using the following ingredients in the stated proportion:

(9) TABLE-US-00001 SWISH Xylitol 84.03% Citric acid 1.13% Silicon dioxide (J M Huber, Zeodent 113) 6.76% Sodium bicarbonate 7.99% 1-menthol 0.025% Spearmint flavour 0.087% 100

(10) Prior to blending, all the components, save for the silicon dioxide, were milled and then sieved through a 60# US Mesh screen, equivalent to a 325 micron particle size. The silicon dioxide, Zeodent 113, manufactured by J M Huber which has a median particle size of 10-15 microns, was then added and blending completed in a V blender. The use of a V blender minimises friction and internal heating of the powder during the blending process. Blending was continued for about 15 minutes.

(11) Prior Art ProductWOW Pink

(12) WOW Pink is made from the identical ingredients to those disclosed above for SWISH and with broadly similar proportions. The formulation is also broadly similar to that disclosed in US 2015/0004560, composition #2, powder oral rinse, save that the sorbitol has been replaced by xylitol, to increase the total xylitol to about 85% w/w.

(13) However, the preparation of the WOW product is different to that of the present invention, in that there is no sieving of the ingredients prior to blending. Furthermore, the ingredients are mixed in a dry ribbon blender, with one half of the amount of xylitol, then the other ingredients added in a bulk and the blender run at a medium rate for less than 5 minutes, and then the remainder of the xylitol is added and the resulting mixture blended for about 10-20 minutes. The resulting white powder is put into polythene lined drums, purged and sealed under nitrogen.

(14) The resulting product is packed into stick packs and sealed under nitrogen.

(15) Gravimetric Vapour Sorption

(16) Approximately 50 mg of sample was placed into a wire-mesh vapour sorption balance pan and loaded into an IgaSorp vapour sorption balance (Hiden Analytical Instruments). The sample was dried by maintaining a 0% humidity environment until no further weight change was recorded (maximum drying time 2 hrs). The sample was then subjected to a ramping profile from 0-40% RH at 5% RH increments, maintaining the sample at each step until equilibration had been attained (99% step completion or a maximum of two hours). Upon reaching equilibration, the percentage RH within the apparatus was ramped to the next step and the equilibration procedure repeated.

(17) The Hydrophilic/Water surface area was then calculated by applying the BET equation to the isotherm obtained. For the prior art product WOW Pink, the Water Surface Area (WSA) was determined to be 97.757 m.sup.2/g. For product according to the invention, SWISH, the WSA was determined to be 180.484 m.sup.2/g.

(18) These results suggest that the product according to the invention, SWISH, will be significantly more wettable than the prior art product, WOW Pink and so more acceptable to consumers. In particular, the product has improved mouth feel compared to the prior art product, WOW Pink.