WO1994014409A1

WO1994014409A1 - Deodorant compositions

Info

Publication number: WO1994014409A1
Application number: PCT/EP1993/003612
Authority: WO
Inventors: Kevin Ronald Franklin; Gordon Robert Wight
Original assignee: Unilever Plc; Unilever N.V.
Priority date: 1992-12-22
Filing date: 1993-12-17
Publication date: 1994-07-07
Also published as: GB9226685D0; ZA939620B; AU5833194A

Abstract

Deodorant compositions for topical application to human skin, e.g. underarm, contain as active agent a layered double hydroxide of the general formula: [Zn(1-x) Alx (OH)2]x+ By-x/y . zH2O where B is an interlayer anion or mixture of anions, y is the charge on the anion, x is 0.1 to 0.5, z is 0 to 100.

Description

DEODORANT COMPOSITIONS

FIELD OF THE INVENTION This invention relates to deodorant actives, and to new compositions containing these deodorant actives which are suitable for topical application to the human skin.

BACKGROUND OF THE INVENTION The deodorant market is dominated with products which rely for their deodorancy effect either on ethanol, or various other metal salts. For example, in EP 024 176 (Unilever) , there is described a deodorant composition containing as an active ingredient zinc carbonate. The composition is an aerosol composition which is designed to reduce axillary odour without suppressing perspiration, and also comprises a water-absorbent anionic polyelectrolyte.

There still exists, however, demand for further deodorant compositions, which may be used on their own or as part of a combined antiperspirant/deodorant composition, which provide a superior degree of efficiency in terms of their ability to control odour generation, in relation to conventional deodorant or antiperspirant/deodorant compositions. Also, conventional compositions may also

SUBSTITUTE SHEET have associated consumer and/or sensory negatives, which ideally can be improved upon.

Hydrotalcites are a known category of minerals. For example, in "Anionic clay materials" by T Reichle,

Chemtech, January 1986 pages 58-63, there is provided a general description of hydrotalcite-type materials. Such minerals are anionic clays, and have a structure broadly similar to brucite (magnesium hydroxide) . In this structure, magnesium atoms are octahedrally surrounded by six oxygen atoms in the form of hydroxide, the octahedra sharing edges to form an infinite sheet. The sheets are generally stacked on top of each other, and linked by hydrogen bonds. However, although they are based on this brucite structure, hydrotalcites are materials in which aluminium cations have replaced some of the magnesium cations.

Because there is an additional unit of positive charge for every aluminium cation that substitutes for a magnesium cation, such materials therefore have located between the metal hydroxide sheets further anions, which maintain the electrical neutrality of the structure. As a result, a hydrotalcite may have a large range of anions associated with it.

The hydrotalcites form part of a larger class of materials with similar structures. These are known collectively as layered double hydroxides. In such materials the magnesium and/or the aluminium ions of hydrotalcite may be replaced by other metal ions.

A general chemical composition for these layered double hydroxides is:

SUBSTITUTESHEET [M₍₁__x)N_x(OH)₂]^x+ B^_x/y • zH₂0 where M is a divalent metal ion N is a trivalent metal ion

B is one or a mixture of interlayer anions y is the charge on the interlayer anions x is normally between 0.1 and 0.5 z is normally between 0 and 100

SUMMARY OF THE INVENTION We have discovered that certain layered double hydroxides may be included in deodorant or antiperspirant compositions, and may provide a surprisingly good degree of efficacy in terms of their ability to control and/or reduce odour, when compared to such notable deodorancy standards as compositions containing zinc carbonate.

Thus, according to the invention, there is provided a deodorant composition suitable for topical application to the human skin, comprising an effective amount of a zinc aluminium layered double hydroxide having the general formula:

[Zn₍₁._x) Al_x (OH)₂]^x+ B^_x/y • zH₂0 where B is an interlayer anion or mixture of anions y is the charge on the anion x is 0.1 to 0.5 z is 0 to 100

We have found that such minerals, when incorporated in physiologically acceptable carriers, surprisingly provide a remarkably good degree of odour control and deodorancy.

A wide variety of anions may be present as the interlayer anion B in the general structure above. These interlayer

SUBSTITUTE SHEΞET anions may be simple inorganic anions but may alternatively be organic anions. Preferred inorganic anions include carbonate, sulphate, chloride and nitrate. Organic anions may be the anions of organic carboxylic acids, e.g. alkanoates such as octanoate and stearate.

In another aspect, this invention provides the use of zinc-containing layered double hydroxide as defined above to inhibit human body malodour, notably by the application to skin of a composition as defined above.

DETAILED DESCRIPTION

As just set forth above, the active ingredients of a composition according to this invention is a layered double hydroxide containing zinc.

Compositions according to the invention preferably contain 0.1% - 30% by weight, more preferably 0.5% - 15% by weight of the layered double hydroxide.

The zinc aluminium layered double hydroxides used in compositions according to the invention may be prepared by several routes. Not wishing to preclude other routes, they may be precipitated from a solution containing a mixture of zinc and aluminium salts (for example nitrates, chlorides and sulphates) , by addition of sodium hydroxide or a similar base , as described by Thevenot et al (Clays and Clay Minerals (1989) 5_. 396) , or by direct reaction of a zinc oxide slurry with an aluminium salt solution. The crystallinity and crystal size of the product may subsequently be increased by ageing the layered double hydroxide in its supernatant at temperatures up to 200°C. Different interlayer anions may be introduced into the layered double hydroxide by ion exchange techniques, or by

SUBSTITUTE SHEET using the partial decomposition-reformation procedure described by Dimotakis and Pinnavaia (Inorganic Chemistry (1990) 13, 2393) .

The physiologically acceptable carrier which is a component of compositions of this invention should be acceptable for topical application to human skin.

Various materials may be used as the carrier, depending on the form of the product. Notably, compositions according to the invention can take the form of liquid or solid products, suitable for topical application to the human skin, especially the underarm. The physiologically acceptable carrier may include materials which have a useful function of their own, for example as emollients. When the composition is in liquid form, it is preferred that liquids constitute a majority of the composition, i.e. from 5% to 99.9% of the composition.

A convenient product form is a solid stick, usually contained in a suitable holder or dispenser to enable it to be rubbed onto an area of the skin, in particular the underarm, where control of perspiration or deodorancy is required.

An alternative and preferred form of compositions according to the invention is a lotion, containing the layered double hydroxide in suspension, which is suitable for example for application from a roll-on dispenser. Such a dispenser enables the product to be rolled onto the skin in an area where odour control is required, which is a conventional manner of application known in the art.

SUBSTITUTE SHEET A further example of a composition according to the invention is a liquid composition for dispensing from an aerosol can pressurized with a volatile propellant. Another, somewhat similar example is a liquid composition for dispensing via a finger operated pump spray to provide for delivery to the skin of a finely divided spray or aerosol, without the use of propellant gas to deliver it.

A composition in the form of a stick may be based on a waxy organic solid or a very viscous gel as carrier material. Commonly such a gel comprises ethanol or aqueous ethanol thickened to form a gel with sodium stearate or other hard soap. Sticks may be based on propylene glycol and on mixtures of alcohol and glycols. These may be gelled by incorporation of dibenzyl sorbitol. Volatile silicone may be gelled to a stick with stearyl alcohol. A material to improve skin feel, such as glycerol, may be included in a stick. Waxes and talc are also frequently included.

A lotion for application from a roll-on dispenser may use a variety of liquids as carrier material. Water may possibly be used, so also may hydrophilic organic liquids such as ethanol, and hydrophobic organic oils. Ethanol and aqueous ethanol containing at least 40% ethanol are commonly used. Usually the liquid phase contains an emollient material which provides desirable skin feel properties, e.g. isopropyl myristate, cetyl alcohol or di- butyl phthalate. A thickener may be included to increase the viscosity of the composition and maintain the solids in suspension.

SUBSTITUTE SHEET A composition for delivery as an aerosol will generally include alcohol, aqueous alcohol or volatile silicone oil as carrier material in addition to any propellant.

It should be noted that compositions according to the invention are suitable not just for application to the axilla, but may be applied to any surface of the body at which the control of odour may be required, such as the foot or crotch.

Ingredients which can be present in compositions according to the invention include:

cosmetically acceptable vehicles, such as straight and branched chain alcohols, for example, ethanol, isobutanol or isopropanol;

volatile and non-volatile silicones, such as dimethyl cyclosiloxanes or polydimethyl siloxane, eg, DOW CORNING fluids DC244, DC245, DC344, DC345, Q2 1465 and the 200 fluids;

antiperspirant active salts, such as those of aluminium or zirconium;

deoperfumes and deodorant compounds which can act as antimicrobial agents.

hydrophobic oils, such as liquid paraffin oils;

inorganic electrolytes, such as sodium chloride or sodium sulphate;

SUBSTITUTE SHEET cationic polymers, such as Abil Quat 3272 and Abil Quat 3270, both ex TH Goldsmidt AG;

thickeners such as clays, for example, Bentone 38, silicas, for example, Aerosil 200 and hydroxypropyl celluloses such as Klucel;

skin feel improvers, such as talc and finely divided polyethylene, an example of which is Acumist B18;

gelling agents, such as stearyl alcohol, sodium stearate or waxes, for example castor wax;

humectants, such as polyols, for example glycerol;

water,-

emollients such as isopropyl myristate;

- perfumes;

preservatives and antioxidants;

skin benefit agents, such as allantoin;

colours,-

other cosmetic adjuncts conventionally employed in stick, roll-on lotion, liquid spray, cream and propellant driven aerosol products.

It should be appreciated that a number of the above ingredients do not contribute to the deodorant function

SUBSTITUTE SHEET but are present to give other benefits and acceptability to the consumer.

The ingredients above may conveniently form up to 99.9% by weight of the composition, more preferably up to 99.5% by weight of the composition.

Compositions of the invention will generally contain a majority of water, organic liquid or a mixture of the two. Frequently the amount will lie in a range from 75 to

99.99% by weight. The amount of organic liquid present may be quite small, but at least 5% by weight will generally be present. Organic liquid may be present in much larger amounts, up to 99.99%, since water may be entirely absent.

SUBSTITUTE SMEE7 Examples

The invention will now be described by way of example only.

Example 1. Synthesis of Zn/Al h droxy nitrate 94.5g of zinc oxide (ZnO) was weighed into a 1 litre polypropylene bottle and then slurried in 250ml water. 1454.lg of aluminium nitrate (Al (N0₃)₃.9H₂0) was then dissolved in 500ml water and then added with stirring to the slurry, the bottle was capped, shaken vigorously, and then placed in a thermostatted oven at 90°C for 6 days. The solid was filtered off, washed thoroughly with water, and then freeze dried. The material was finally equilibrated with water vapour at a water activity of 0.75.

The material was confirmed by x-ray diffraction to be a layered double hydroxide.

Example 2. Conversion to Zn/Al Hvdroxy Stearate A solution of potassium stearate was first prepared by dissolving 40.66g of stearic acid with 8.34g of potassium hydroxide in 700ml water and heating it to about 70°C. 50g of Zn/Al hydroxy nitrate as prepared above was placed in a 1L polypropylene bottle and the potassium stearate solution was added. The bottle was capped and shaken for 2 minutes, and then placed in a thermostatted oven at 90°C for 18 hours. The solid was then filtered off, washed thoroughly with hot water, and freeze dried. The material was finally equilibrated with water vapour at a water activity of 0.75.

SUBSTITUT The material was confirmed by x-ray diffraction to be a layered double hydroxide.

The chemical composition was determined by analysis to be Zn₄Al₂ (OH) ₁₂ (stearate)_2-1 . 2.9H₂0.

The zinc content was 22.9% by weight.

In directly analogous manner, the method of this Example was used to prepare: Zn/Al hydroxy laurate whose composition was determined to be

Zn₄Al₂ (OH) ₁₂ (laurate)₂ . 4.2H₂0 and

Zn/Al hydroxy octanoate whose composition was determined to be Zn₄Al₂ (OH) ₁₂ (octanoate)₂ . 4,5H₂0. The zinc contents of these materials were 26.9% and 30.4% by weight respectively.

SUBSTITUTE SHEET

Example 3

The following compositions were made up simply by blending together the components under high shear:

Composition (%w/w) o 3 Zinc content of

Component the component 1 2 3 4 (% by weight)

Zinc Aluminium Hydroxy 37.5 8.0 m 10 Nitrate (1) to Zinc Aluminium Hydroxy 30.4 8.0 x Octanoate (2)

[ rnπ Zinc Aluminium Hydroxy 22.9 8.0 Stearate (3)

15 Basic Zinc Carbonate (4) 57.1 8.0

Anhydrous Ethanol 2.5 2.5 2.5 2.5

Volatile Silicone DC344 (5) 86.5 86.5 86.5 86.5

Distilled Water 1.0 1.0 1.0 1.0

Bentone 38 (6) 2.0 2.0 2.0 2.0

20

(1) prepared as described in Example 1 above

(2) prepared as described in Example 2 above

(3) prepared as generally described in Example 2 above

(4) zinc carbonate hydroxide monohydrate powder, ex BDH (5) ex Dow Corning

(6) a hydrophobed clay, dimethyl distearyl ammonium hectorite ex Rheox

Composition 4 was provided for comparison only.

Compositions 1 and 2 were made up by simply blending together the components of the composition at high shear. The compositions were lotions, and were packaged in roll- on applicators.

The effectiveness of the compositions was assessed by the following procedure. Results obtained are tabulated below.

Test Protocol

The test protocol uses a team of 3 experienced trained expert assessors. The test panel used between 40 and 50 female volunteers using approximately 25 axillae per product, and malodour was assessed on an increasing scale of 0-5.

Procedure

On the first day of the test, the panellists' axillae are washed with unperfumed soap. Panellists are allocated a different product for each axilla, which is applied as a fixed weight of product on any given occasion. After 24 hours of wear of the test product on each application, the

SUBSTITUTE SHE odour intensity of each axilla is evaluated by each assessor in turn, assigning an odour intensity score.

After each assessment, the panellists are washed and the products reapplied. The protocol is repeated over four successive days. The dosage applied on any occasion was determined by weighing the product container before and after application.

SUBSTITUTE SHEET Results

Composition Mean Malodour Mean Dosage Score (Mg)

1 1.65 340

2 1.94 360

3 1.92 340

4 (Control) 1.88 360 In these tests the least difference which was significant at the 95% confidence level was 0.23.

This result indicates that the composition containing the nitrate form of zinc aluminium layered double hydroxide is significantly more effective than the zinc carbonate positive. The other layered double hydroxides also show a significant deodorant efficacy, approximately matching zinc carbonate.

Example 4

This utilised a similar test protocol to that described above, except that the odour assessment was carried out 7 hours after product application on 3 successive days using 13 panellists. The results are presented as a mean result for all assessment days.

SUBSTITUTE SHEET Test Compositions

Component Composition

5 6

Zinc Aluminium Hydroxy nitrate (1) 10.0

Zinc Carbonate (4) 10.0

Volatile Silicone DC344 (5) 85.0 85.0

Bentone 38 (6) 3.0 3.0

Anhydrous Ethanol 1.0 1.0

Demin. Water 1.0 1.0

Results

Composition Mean Malodour Score Mean Dosage (Mg)

5 1.45 339

6 1.69 329

This result indicated that, in this test, the zinc aluminium hydrotalcite composition exhibited a superior deodorancy effect to the zinc carbonate-containing control . Additionally this result was significant at a confidence level of greater than 99%.

Example 5

Volatile silicone aerosol deodorant sprays have the following composition:

SUBSTITUTE SHEET wt

Zinc aluminium hyroxy nitrate l.0

Volatile silicone oil (Dow Corning DC 244) 9

Bentone 38 0.5

Ethanol 0.5

Butane balance to 100%

The butane functions as propellant, giving a pressure of 3.2 bar.

Example 6

An alcoholic aerosol spray has the following composition:

wt%

Zinc aluminium hydroxy stearate 1.0

Ethanol 46.5

Butane 50

Perfume 1.5

Isopropyl myristate 1.0

The butane functions as propellant, giving a pressure of 3.2 bar.

Example 7 Two further aerosol sprays have the compositions:

wt %

Zinc aluminium hydroxy nitrate 1.0 1.0 Water 20 20 Perfume 0.5 1.5

Dimethyl ether propellant 50 50 Ethanol ance to balance to

100% 100%

SUBSTITUTE SHEET Aerosol composition are prepared by first making a suspension concentrate by blending and homogenising all the ingredients except the propellant. The concentrate is placed in a container which is then sealed with a suitable aerosol valve and pressurised with the propellant.

Example 8

A composition based on volatile silicone oil, suitable for filling into roll-ball applicators, has the composition: wt %

Zinc aluminium hydroxy alkanoate 8

Bentone 38 1 to 5

Perfume 0 to 2

Alcohol 0.5 Volatile silicone oil balance to 100%

(Dow Corning DC 345)

Example 9

Two alcoholic compositions for roll-ball applicators are:

wt

Zinc aluminium hydroxy nitrate 5 5

Perfume 0 to 2 0 to 2

Hydroxypropyl cellulose thickener 0 to 1 0 to 1 (Klucel M from Avalon/Hercules)

Ethanol 80 20

Water balance to balance to

100% 100%

Example 10

Three compositions for delivery from pump sprays are:

SUBSTITUTE SHEET wt%

Zinc aluminium hydroxy nitrate 1 1 1

Perfume 1.5 2 1.5

Isopropyl myristate 0.5 1 1 Ethanol 75 25 86.5

Water to 100 to 100

Volatile silicone oil (Dow Corning Q2 1465)

Example 11

This is a deodorant product in the form of a stick, containing volatile silicone: wt %

Zinc aluminium hydroxy stearate 8 Stearyl alcohol ^• 22

Castor wax MP80 1

Perfume 2

Volatile silicone oil DC 345 67

Example 12

Further examples of stick are: wt

Zinc aluminium hydroxy nitrate 8 8

Sodium stearate 6 6

Perfume 2 2

Ethanol 74 --

Water 10 30

Propylene Glycol -- 54

Example 13

A product in the form of a deodorant cream is:

SUBSTITUTE SHEET wt

Isopropyl myristate 10.0

Mineral oil 15.0

Cetyl alcohol 2.0

Ethoxylated cetyl alcohol (20EO) 0.5

Zinc aluminium hydroxy nitrate 8.0

Glycerine 2.0

Propyl paraben 0.1

Methyl paraben 0.2

DMDM hydantoin 0.2

Water to 100

Example 14

A composition in the form of an emulsion suitable for filling into roll-ball applicators is: wt

Glyceryl tricaprylin 5.0

Steareth-21* 1.0

Steareth-2* 2.5

Zinc aluminium hydroxy nitrate 8.0

Propyl paraben 0.1

Methyl paraben 0.2

Phenoxyethanol 0.4

Water to 100

* ethoxylated stearyl alcohol with average 21EO and average 2 EO respectively.

SUBSTITUTE SHEET

Claims

1) A deodorant composition suitable for topical application to the human skin, comprising an effective amount of a zinc aluminium layered double hydroxide having the general structure;

[Zn₍₁._x)Al_x(OH)₂]^x+ B^_x/y • zH₂0, wherein B is one or more interlayer anions y is the charge on the anions x is 0.1 to 0.5 z is 0 to 100, in a physiologically acceptable carrier.

2) A deodorant composition according to claim 1 wherein the composition comprises 0.1-30% by weight of the layered double hydroxide.

3) A deodorant composition according to claim 1 or claim 2 wherein the composition comprises from 50 to 99.9% by weight of the carrier.

4) A deodorant composition according to any one of the preceding claims which is in the form of a solid stick.

5) A deodorant composition according to any one of claims 1 to 4 which is in the form of a liquid,

^{^}containing the layered double hydroxide in suspension.

6) A deodorant composition according to claim 5 wherein. the carrier comprises an organic liquid.

SUBSTITUTE SH 7) A method of reducing human body odour comprising applying topically to human skin a composition as defined in any one of claims 1 to 6.

SUBSTITUTE SHEET