The present invention relates to an oral care composition that when coated onto the teeth aids tooth whitening and prevents staining.

Background of the Invention White teeth are seen as cosmetically attractive, however the enamel of the teeth can stain, for instance when certain foods or drinks are consumed. Hence, there is a need for products and devices to prevent/mitigate the staining of teeth.

Background

WO2014205631 discloses an oral care composition containing (a) a zinc citrate; and (b) a surface-active organophosphate compound. The composition is said to prevent stain from depositing on a tooth surface or other oral surfaces.

Methods for reducing or preventing the staining capacity of a compound to a tooth are disclosed in W014152829. The method includes the step of coating the tooth with a film comprising starch polymer or copolymer that is formed by crosslinking a starch. WO 2013/070184 discloses dental whitening compositions, comprising an

acrylate/octylacrylamide copolymer and one or more alkyl cellulose ethers. The compositions are said to prevent the teeth from staining.

Dental coating kits that are said to prevent teeth from staining are disclosed in

EP1550428 and EP2854756.

With many tooth whitening products the teeth can appear coated with a film and the white shade of the teeth looks unnatural. There remains the need for a tooth whitening composition that gives the teeth a natural shade of white and adheres to the teeth in a manner such that the teeth do not look like they are coated. The compositions of the present invention when applied to the teeth give the teeth a naturally white appearance. Compositions according to the invention also mitigate tooth staining.

Description of the Invention

The present invention relates to a composition comprising a whitening ingredient, smectite clay and an acryl based polymer.

The invention further relates to the use of the composition comprising a whitening ingredient, smectite clay and an acryl based polymer for prevention of staining.

Detailed Description of the Invention

Compositions of the invention comprise a whitening agent. Suitable whitening agents include materials with a high refractive index or blue dyes/pigments. In the context of the present invention a high refractive index is means materials with a refractive index of at least 2.0, more preferably at least 2.2, even more preferably at least 2.3, even more preferably still at least 2.4 and most preferably at least 2.5. The maximum refractive index of the material is not particularly limited but preferably the material has a refractive index up to 3.0, more preferably up to 2.9. Suitable materials to provide such a high refractive index are limited only in that they should be suitable for use in oral hygiene applications. Particularly suitable are metal salts and micas. Preferred are salts where the metal is selected from zinc (Zn), titanium (Ti) or a combination thereof. Additionally or alternatively the metal salt is (or at least comprises) a metal oxide. Especially preferred metal oxides are zinc oxide (ZnO), titanium dioxide (T1O2), micas or a combination thereof. Most preferred, owing to their high refractive index and suitability for oral application are micas and titanium dioxide (T1O2), especially preferred is mica coated with titanium dioxide. Preferably the level of material with a high refractive index, more preferably a metal salt, in particular titanium dioxide and/or mica is from 0.1 to 8 wt% of the total composition, more preferably it is from 0.5 to 4 wt%. The whitening agent can also be a blue colourant such as a pigment or blue dye, preferably it is a blue dye more preferably it is Patent blue.

Preferably, the level of blue colourant, more preferably blue pigment of blue dye is from 0.0005 wt% to 0.05 wt% of the total composition, more preferably from 0.0001 wt% to 0.01 wt%

Preferably, the composition comprises mixtures of whitening agents, more preferably a mica and a blue dye, most preferably the composition comprises mica coated with ΤΊΟ2 and patent blue.

Preferably, the weight ratio of any of the above mentioned combinations of metal salt/mica to blue colourant, more preferably titanium dioxide to blue dye, is from 2000:1 to 750:1 , more preferably from 1500:1 to 1000:1. Compositions according to the invention comprise a smectite clay, more preferable a montmorillonite clay.

Preferred smectite clays are selected from montmorillonites (bentonites, hectorites and derivatives thereof)(organically modified montmorillonite clays) such as quaternium-18 bentonite, quaternium-18 hectorite, stearalkonium bentonite and stearalkonium hectorite and mixtures thereof. Stearalkonium hectorite is particularly preferred.

Preferred compositions comprise from 5 to 25 wt% of the total composition of the above mentioned clay. More preferred compositions have 8 to 15 wt% of the total composition of the above mentioned clay.

The clay is believed to help the thickening of the product, in this way the extrusion from the container is facilitated and the dispersibility of the whitening material in particular the mica, in this way the appearance of the composition on the teeth look homogenous and natural.

Compositions of the invention comprise an acryl based polymer, more preferably an acrylate / octylacrylamide copolymer for example a copolymer of octylacrylamide (for example N-(1 , 3,3-tetramethylbutyl)-propenamide) and one or more monomers selected from acrylic acid, methacrylic acid and their simple esters, in a particular embodiment, the acrylate / octylacrylamide copolymer is 2-propenoic acid, 2-methyl- 2-methylpropyl ester, polymer with 2-propenoic acid and N-(1 ,1 ,3,3 -tetramethylbutyl)-2-propenamide (example DERMACRYL 79 (commercially available from National Starch or Akzo Nobel).

Preferably the level of acryl based polymer is from 2 to 20 Wt % of the total composition, more preferably from 5 to 15 wt% of the total composition. Preferably which the weight ratio of clay to acryl based polymer is from 1 .3 :1 to 1 :1 Compositions according to the invention will usually contain a continuous phase, which may comprise water and/or alcohol more preferably a polyhydric alcohol. The amount of alcohol, preferably polyhydric alcohol generally ranges from 20 to 85 wt% (based on the total weight of the composition), preferably the level of water is 7 wt% or below and the level of alcohol is from 30 wt%. to 75 wt% of the total composition.

A preferred alcohol for use in the present invention and at the present invention is isopropyl alcohol. In a preferred embodiment the composition comprises an ester in the continuous phase, more preferably ethyl acetate. Preferably the level of ethyl acetate is form 10 to 30 wt% of the total composition more preferably form 15 to 25 wt%.

The oral care composition of the present invention may contain a variety of other ingredients which are common in the art to enhance physical properties and performance. These ingredients include antimicrobial agents, anti-inflammatory agents, anti-caries agents, plaque buffers, fluoride sources, vitamins, plant extracts, desensitizing agents, anti- calculus agents, biomolecules, flavours, proteinaceous materials, preservatives, opacifying agents, micas, colouring agents, pH-adjusting agents, sweetening agents, particulate abrasive materials, polymeric compounds, buffers and salts to buffer the pH and ionic strength of the compositions, and mixtures thereof. Such ingredients typically and collectively makeup less than 20 percent by weight of the composition, and preferably, from 0.0 to 15 percent by weight, and most preferably, from 0.01 to 12 percent by weight of the composition, including all ranges subsumed therein.

It is highly preferable if compositions of the invention are orally acceptable. By "orally acceptable" it is meant that the compositions are safe for use in the mouth at the levels required.

Example of the invention will now be illustrated by the following non-limiting examples:

Table 1

Example 1 Example 2 Example

Trade Name INCI name Wt% Wt% A

Dermacryl 79 Acrylate/Octylacrylamide 10 15 -

Eudragit RL copolymer of ethyl acrylate, 7

methyl methacrylate

methacrylic acid ester with

quaternary ammonium

groups

Bentone gel C12-15 alkyl benzoate, 12 12

TN V stearalkonium hectorie,

propylene carbonite

Titanium dioxide 1.5 1 .5 1 .0

Ethyl acetate 20 20

Patent Blue C I 42051 0.00125 0.00125 0.00125 Patent

Titanium Dioxide 1.5 1 .5 1 .0

Ethyl cellulose - - 4.0

PEG -3000 - - 2.0

Isopropyl alcohol and minor To 100 To 100 To 100 Examples 1 and 2 when coated on the teeth enhanced the white appearance and yet the enhancement did not look unnatural nor did the teeth appear coated

The following Examples were applied to enamel bovine chips and were tested against staining solutions prepared from Black tea. Delata E was calculated. 12 measurements were made per calculation and the average calculated.

The results are presented in Table 2

Table 2:

The results of table 2 demonstrate that Examples of the invention prevent the staining of the teeth.

The following compositions were prepared.

Table 3

The sedimentation of the above Examples was measured and is recorded in Table 4 below

Table 4

Examples according to the invention coated the teeth with a natural looking film yet had acceptable sedimentation and viscosity.