FIELD OF THE INVENTION

The invention relates to an antiperspirant composition, more particularly it relates to an aqueous antiperspirant composition.

BACKGROUND OF THE INVENTION

Antiperspirant products are designed to control sweating. They include an antiperspirant active which is usually dissolved or dispersed in a carrier material. This formulation is in turn dispensed from a pack to the consumer's body, usually to the underarm area.

SUMMARY OF THE INVENTION

There is a problem that for some aqueous antiperspirant compositions, they do not exhibit the required thermal stability at high temperatures. This improvement is particularly striking at temperatures around 50°C and above. Such a problem with thermal stability means that it is difficult to effectively formulate a product suitable for global application. The thermal instability of the product at higher temperatures also leads to a product that can be less effective at its primary role of sweat control. It is an object of the invention to improve the thermal stability of aqueous antiperspirant compositions.

We have now found that the thermal stability of an aqueous antiperspirant composition can be improved by utilising a certain combination of materials, namely a glyceryl mono- or di- ester, a fatty alcohol and a triglyceride oil in specified amounts and weight ratios.

This combination of ingredients allows for improved thermal stability, such as stability for 7 days at 50°C or even 55°C without phase separation. There is provided in a first aspect of the invention, an aqueous antiperspirant composition comprising:- a) from 5 to 30 wt.%, preferably from 10 to 20 wt.% of an antiperspirant active;

b) from 1 to 5 wt.%, preferably from 1.25 to 4 wt.%, more preferably from 1.5 to 3 wt.% of a glyceryl mono- or di- ester; c) from 0.5 to 5 wt.%, preferably from 1 to 4 wt.%, more preferably from 1 .5 to 3 wt.% of a fatty alcohol;

d) from 1 to 8 wt.%, preferably from 1.5 to 6 wt.%, more preferably from 2 to 5 wt.% of a triglyceride oil; and,

e) from 30 to 90 wt.% of water, preferably from 50 to 85 wt.%, more preferably from 60 to 80 wt.% of water; wherein the weight ratio of b) to c) is from 1 :2 to 2:1 ;

wherein the weight ratio of b) to d) is from 1 :3 to 3:1 ; and,

wherein the formulation contains, on a wt.% basis, more (b) than any ethoxylated fatty alcohol containing C14-C20 carbon atoms, wherein the degree of ethoxylation is between 1 to 2 moles of ethoxylate per mole of fatty alcohol, and wherein said ethoxylated fatty alcohol if present, is present at a level of less than 1 wt.%. A second aspect of the invention provides a roll-on deodorant product comprising: a roll- on deodorant package comprising a roll-ball for dispensing a liquid formulation; and, the formulation of the first aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The antiperspirant composition is aqueous. Water is present at a level of from 30 to 90 wt.%, preferably from 50 to 85 wt.%, more preferably from 60 to 80 wt.%. The composition may take on the form of an oil-in water emulsion.

The antiperspirant composition comprises an antiperspirant active.

Preferably the level of antiperspirant active present in the composition is from 5 to 30 wt.%, more preferably from 10 to 20 wt.%.

Preferably, the antiperspirant active comprises aluminium. Examples of aluminium containing antiperspirant active materials include: aluminium chlorohydrate, aluminium chloride, aluminium chlorohydrex polyethylene glycol, aluminium chlorohydrex propylene glycol, aluminium dichlorohydrate, aluminium dichlorohydrex polyethylene glycol, aluminium dichlorohydrex propylene glycol, aluminium sesquichlorohydrate, aluminium sesquichlorohydrate polyethylene glycol, aluminium sesquichlorohydrate propylene glycol, aluminium-zirconium octachlorohydrate, aluminium-zirconium octachiorohydrex gly, aluminium- zirconium pentachlorohydrate, aluminium-zirconium pentachlorohydrex gly, aluminium- zirconium tetrachlorohydrate, aluminium-zirconium tetrachlorohydrex gly, aluminium-zirconium trichlorohydrate, aluminium-zirconium trichlorohydrex gly, and combinations thereof.

Preferably the aluminium antiperspirant active is water soluble. More preferably the aluminium antiperspirant active is aluminium chlorohydrate (ACH). The composition contains from 1 to 5 wt.%, preferably from 1 .25 to 4 wt.%, more preferably from 1 .5 to 3 wt.% of a glyceryl mono- or di- ester.

Glyceryl esters are esters of glycerol. Glycerol is a trihydric alcohol; the glyceryl ester is a mono- or, di- ester of glycerol. These esters can be the same or different. To form the glyceryl ester, the alcohol of the glycerol is reacted with a carboxylic acid species.

Preferred glyceryl esters use glycerol reacted with fatty acids.

Preferably the glyceryl mono- or di- ester is a glyceryl ester of a C12-C22 fatty acid, preferably a glyceryl ester of a saturated C12-C22 fatty acid. More preferably, the glyceryl ester is a glyceryl monoester of a C12-C22 fatty acid, preferably glyceryl monostearate.

The composition comprises from 0.5 to 5 wt.%, preferably from 1 to 4 wt.%, more preferably from 1 .5 to 3 wt.% of a fatty alcohol. Fatty alcohols generally comprise long chain alkyl groups terminating in a primary alcohol. The long chain alkyl group can be for example Cs to C24. The alkyl group may be straight chain or branched, and may be saturated or unsaturated.

Preferably the fatty alcohol is a straight chain alkyl which is unsaturated. More preferably the fatty alcohol is a C10-C20 fatty alcohol, preferably C12-C18 fatty alcohol.

The composition comprises from 1 to 8 wt.%, preferably from 1.5 to 6 wt.%, more preferably from 2 to 5 wt.% of a triglyceride oil. The triglyceride oil is a glycerol having three ester linkages.

Preferably the triglyceride oil comprises glycerol that have been reacted with three Cu- C20 fatty acids. More preferably the triglyceride oil comprises glycerol that have been reacted with three with C16-C18 saturated and/or unsaturated fatty acids. Even more preferably the triglyceride oil comprises unsaturated C16-C18 fatty acids.

The triglyceride oil is most preferably sunflower seed oil. The weight ratio of the glyceryl mono- or di- ester to the fatty alcohol is from 1 :2 to 2:1 , preferably from 1.5:1 to 1 :1.5, more preferably from 1 .2:1 to 1 :1.2.

The weight ratio of the glyceryl mono- or di- ester to the triglyceride oil is from 1 :3 to 3:1 , preferably from 1 :2.5 to 2.5:1 , more preferably from 2:1 to 1 :2.

Preferably, the weight ratio of the fatty alcohol to the triglyceride oil is from 1 :3 to 3:1 , preferably from 1 :2.5 to 2.5:1 , more preferably from 2:1 to 1 :2.

The composition may optionally, but preferably comprise from 0.1 to 5 wt.%, preferably from 0.15 to 2.5 wt.%, more preferably from 0.2 to 1 wt.% of an ethoxylated fatty alcohol containing C14-C20 carbon atoms, wherein the degree of ethoxylation is between 10 to 25 moles of ethoxylate per mole of fatty alcohol. A preferred material is steareth-20, which is stearic acid a (C18 fatty acid) ethoxylated with an average of 20 moles of ethoxylation. The composition may optionally comprise a humectant or emollient to aid the sensory profile. This material is preferably included at a level of from 0.5 to 20 wt.%, preferably from 1 to 10 wt.%. A preferred humectant is glycerol, present at a level of from 1 to 6 wt.%, preferably 2 to 5 wt.%. Typically the antiperspirant composition may comprise a perfume. This may be in the form of a free perfume oil or mixture of perfume oils, or in the form of an encapsulated perfume. Where perfume is included, then preferably the weight ratio of triglyceride oil (d) to perfume is > 1 :1 , more preferably from 10:1 to 1.5:1 , most preferably from 8:1 to 1.25:1.

The formulation contains, on a wt.% basis, more of (b) than, if present, any ethoxylated fatty alcohol containing C14-C20 carbon atoms, wherein the degree of ethoxylation is between 1 to 2 moles of ethoxylate per mole of fatty alcohol.

Said ethoxylated fatty alcohol if present, is present at a level of less than 1 wt.%. Thus, the formulation limits the amount of ethoxylated fatty alcohol having a low amount of ethoxylation to at most 1 wt.%. This has been found to provide a product that feels milder to the consumer, and displays a higher thermal stability as measured by differential scanning calorimetry (DSC).

The formulation contains less than 1 wt.%, preferably less than 0.5 wt.%, more preferably less than 0.1 wt.%, even more preferably less than 0.05 wt.%, more preferably is free from an ethoxylated fatty alcohol containing C14-C20 carbon atoms, wherein the degree of ethoxylation is between 1 to 2 moles of ethoxylate per mole of fatty alcohol.

In some cases the degree of ethoxylation may be between 1 to 4 moles of ethoxylate per mole of fatty alcohol.

This means that in its broadest form, the formulation contains on a wt.% basis, more glyceryl mono- or di- ester (when present at 1 wt.%) than (if present) any ethoxylated fatty alcohol containing C14-C20 carbon atoms, wherein the degree of ethoxylation is between 1 to 2 moles of ethoxylate per mole of fatty alcohol.

The composition may optionally comprise additional ingredients such as stabilisers, preservatives, antioxidants and the like. Typical inclusion levels of each may be from 0.01 to 1 wt.%. Examples of such materials are salts of ethylene diamine tetraacetic acid (EDTA) and pentaerythrityl tetra-di-t-butyl hydroxyhydrocinnamate.

The composition is an aqueous antiperspirant formulation. This composition may be dispensed to the consumer in many forms. A preferred dispenser to dispense the formulation to the consumer is a roll-on deodorant product comprising: a roll-on deodorant package comprising a roll-ball for dispensing an aqueous composition; and, the antiperspirant composition as described herein according to the invention.

Preferably the composition has a viscosity of between 1 ,000 and 12,000 cps, more preferably between 3,000 and 10,000, even more preferably between 3,500 to 8,000. These values are as measured on a Brookfield viscometer (Model DV-I+, RV3 spindle at 10rpm for 30 seconds at 25°C).

The formulations can be manufactured using the following process. The oils, including glyceryl mono- or di- ester, fatty alcohol, triglyceride oil and any further optional oils such as ethoxylated fatty alcohol or glycerol, are heated at 60°C to produce a melt. This is slowly added over a few minutes under shear to water heated to 60°C. The mixture is maintained with shear at 60°C for a few minutes, and subsequently cooled to about 58°C under shear for about 10 minutes. After cooling to about 50°C, the aluminium salt as a solution in water (in this case ACH) is added over a few minutes under shear. The mixture is cooled to about 40°C and any minors such as perfume, antioxidants are then added. The formulation can then be discharged from the mixing vessel into the packaging. The formulation exhibits improved thermal stability over current products. The

formulation of the invention is stable at 50°C or even 55°C without phase separation for at least 7 days. The formulation of the invention has been found to have a higher melting peak, measured by DSC to be 59°C. Examples

Example 1 - comparison of thermal stability against current in-market product

The formulation of the invention (1 ) has been compared to a current in-market product (A) as a comparative example to check the thermal stability. The formulations were tested at 50°C. The formulations are shown in table 1. Table 1

Stability test at 50°C

Formulations 1 and A were tested for thermal stability by keeping them in a temperature controlled environment for a specified length of time measured in days.

Product A (comparative) started to display instability from day 4, and phase separated on day 6.

Product 1 (invention) was completely stable even after 84 days at 50°C.

Example 2 - comparison of thermal stability

The formulation of the invention (1 ) has been compared to an antiperspirant lotion (B) which is comparative. Although this lotion contains the specified combination of materials, namely a glyceryl mono- or di- ester, a fatty alcohol and a triglyceride oil, they are not present in the required levels and/or weight ratios. The formulations are shown in table 2. Table 2

Thermal Stability measured by DSC

The phase transition temperature was measured by differential scanning calorimetry (DSC).

Measurements were performed in a Discovery Series DSC (TA Instruments) and analysed using Trios software (v3.3.1.4246). Samples were measured in aluminium pans and lids with a capacity of -180°C - 600°C (pan vol 40ul, 2-3 atmosp. Internal pressure). A measurement range from 10°C to 90°C and a heating rate of 10°C/min was used. Formulation B showed a much lower onset temperature of phase transition of <45°C. Formulation 1 had a much higher onset temperature of phase transition of 57°C, with a peak value of 59°C.