EP4637676A1

EP4637676A1 - Antiperspirant aerosol composition

Info

Publication number: EP4637676A1
Application number: EP23813392.0A
Authority: EP
Inventors: Elodie Aurore Suzanne Deguerville; Sophie Carol HUGHES; Andreas Stavros POULOS; Ophelie Marie-Pierre Cecile TORRES
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Priority date: 2022-12-22
Filing date: 2023-11-28
Publication date: 2025-10-29
Also published as: MX2025007107A; AU2023411413A1; AR131447A1; WO2024132397A1

Abstract

An anhydrous antiperspirant aerosol composition comprising a relatively low level of an AP active which is aluminium sesquichlorohydrate activated by a water-soluble calcium salt and an amino acid, and a carrier oil which is free from volatile cyclic silicone oil and which comprises a C12-C16 branched chain alkane having a refractive index within 0.13 of that of the AP active.

Description

ANTIPERSPIRANT AEROSOL COMPOSITION

Field of Invention

The present invention relates to antiperspirant (AP) aerosol compositions having high efficacy and reduced environmental impact, in particular compositions which are free from volatile cyclic silicone oils.

Background

There are numerous publications describing aerosol compositions with carrier oils that are used as alternatives to or in addition to volatile cyclic silicone oils.

EP 792,634 B1 (Unilever, 2003) discloses AP aerosol compositions comprising activated aluminium chlorohydrate (ACH), masking oil and a propellant, wherein the ACH comprises non-hollow particles.

US2009/123398AA (Preserve Inc., 2009) discloses non-silicone compositions consisting of about 35% of a C12-C14 paraffin, about 55% of a C13-C16 isoparaffin, and about 10% of a further component selected from a C13-C15 mixed alkane and a cosmetically acceptable oil.

US2010/068162 AA (Lipo Chemicals Inc., 2010) discloses compositions comprising 30 to 90% of a volatile hydrocarbon, 10 to 70% of a non-volatile hydrocarbon and 0.1 to 10% of a polymeric ester.

Summary of the Invention

It is an object of the present invention to provide an AP aerosol composition which is free from volatile cyclic silicone oils and which still delivers good sensory benefits. It is a further object of the present invention to provide an AP aerosol composition which delivers excellent antiperspirancy without undue staining of clothing worn in close proximity to the site of application of the composition.

It is a further object of the present invention to provide an AP aerosol composition which delivers good to excellent rheological stability, particularly before the addition of any propellant that might be employed.

In a first aspect of the invention there is provided an anhydrous AP aerosol composition comprising an AP active which is aluminium sesquichlorohydrate activated by a water- soluble calcium salt and an amino acid, and a carrier oil which is free from volatile cyclic silicone oil and which comprises a C12-C16 branched chain alkane having a refractive index (Rl) within 0.13 of that of the AP active, wherein the AP active is present at less than 40% by weight of the composition, excluding any propellant that may be present therein.

In a second aspect of the invention there is provided a method of manufacture of an anhydrous AP aerosol composition according to the first aspect of the invention.

In a third aspect of the invention there is provided a non-therapeutic method of achieving a reduction in perspiration from the human body comprising the topical application of an anhydrous AP aerosol composition according to the first aspect of the invention.

In an aspect of the invention closely related to the third aspect of the invention described immediately, there is provided the non-therapeutic use of an anhydrous AP aerosol composition according to the first aspect of the invention to reduce perspiration from the surface of the human body following topical application thereof.

Detailed Description

Herein, the term “anhydrous” should be understood to mean “essentially anhydrous”, comprising less than 1% by weight of water, excluding any water that is chemically bound to solids within the composition, such as the AP active. Herein, an aerosol composition is a liquid composition capable of forming an aerosol when expelled through an orifice suitable for producing an aerosol.

Herein, the “base composition” is the full composition excluding any propellant that may be present therein, unless indicated otherwise.

Herein, topical application refers to application to the skin of the human body, in particular to the underarm regions of the human body.

Herein, antiperspirant actives are materials that reduce perspiration on the skin of the human body, typically following topical application.

Herein, methods and uses should be understood to be cosmetic methods/uses, i.e. non- therapeutic methods/uses. Likewise, compositions of the invention are cosmetic compositions.

Herein, all percentages, parts, and ratios are by weight, unless otherwise indicated.

Herein, references to an amount of a material or materials refer to the total amount of material(s) of the type indicated.

Herein, references to an amount of a material are with reference to the total composition of which it is a part, unless otherwise indicated.

Herein, “application” and “applied” relate to application to the skin of the human body, in particular the underarm regions, unless the context dictates otherwise.

Herein, features expressed as “preferred” with regard to a particular aspect of the invention should be understood to be preferred with regard to each aspect of the invention. Herein, preferred, particularly preferred and especially preferred features of the invention are particularly preferred when used in combination with other preferred, particularly preferred, and especially preferred features of the invention.

Herein, “ambient conditions” refer to 20°C and 1 atmosphere pressure, unless otherwise indicated.

Herein, the word “comprising” is intended to mean “including” but not necessarily “consisting of” or “composed of.” In other words, the listed steps or options need not be exhaustive.

Herein, except in the examples or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material, physical properties of materials and/or use are to be understood as modified by the word “about”.

Herein, numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Herein, refractive index (Rl) is measured using standard methods in the art under ambient conditions.

The AP active used in the present invention is an aluminium sesquichlorohydrate (ASCH) activated by a water-soluble calcium salt and an amino acid. Such actives are described in EP 2,999,452 B1 (Unilever, 2017), EP 3,212,296 B1 (Unilever, 2019) and in other publications.

The ASCH is an AP salt having the chemical formula AI2OH4.4CI1.6 to AI2OH4.9CI1.1. Most commercial ASCH samples are of chemical formula AI2OH4.7CI1.3 to AI2OH4.9CI1.1 and it is preferred to have ASCH salts of this formula. The AP active is formulated with a water-soluble calcium salt and an amino acid to achieve activation.

The water-soluble calcium salt is preferably used at such a level that the molar ratio of calcium to aluminium is at least 1 :40, more preferably at least 1:30 and most preferably at least 1:20. It is not advantageous to have the calcium concentration in excess of the aluminium concentration; indeed, it is preferred that the calcium concentration is no more than half that of the aluminium concentration and more preferred that it is no more than a fifth of said concentration. For the preferred molar ratios of calcium to aluminium of at least 1 :40 and at least 1 :20, it is independently preferred that this ratio is no greater than 1 :2 and more preferred that it is no greater than 1 :5.

In particularly preferred embodiments, the molar ratio of calcium to aluminium is at least 1 :15 and preferably no greater than 1 :5 and in especially preferred embodiments it is at least 1:10 and preferably no greater than 1 :5.

A preferred water-soluble calcium salt for use in the present invention is calcium chloride.

Herein, references to molar amounts and ratios of “aluminium” are calculated on the basis of mono-nuclear aluminium, but include aluminium present in poly-nuclear species; indeed, most of the aluminium in the salts of relevance is present in poly-nuclear species.

The amino acid is preferably used at such a level that the molar ratio of amino acid to aluminium is at least 1 :20, more preferably at least 1 :10 and most preferably at least 1:5. It is not advantageous to have the amino acid concentration in excess of the aluminium concentration; hence, the molar amino acid to aluminium is preferably from 1 :20 to 1 :1, more preferably from 1:10 to 1:1 and most preferably from 1:5 to 1 :1.

In particularly preferred embodiments, the molar ratio of amino acid to aluminium is at least 1:4 and preferably no greater than 1:1 and in especially preferred embodiments it is at least 1 :3 and preferably no greater than 1 :1. In preferred embodiments, the molar ratio of calcium to aluminium is at least 1 :40 and the molar ratio of amino acid to aluminium is at least 1 :20. In further preferred embodiments the molar ratio of calcium to aluminium is at least 1 :20 and the molar ratio of amino acid to aluminium is at least 1 :10. In particularly preferred embodiments the molar ratio of calcium to aluminium is from 1 :20 to 1 :5 and the molar ratio of amino acid to aluminium is from 1:10 to 1 :1.

The above indicated preferences for calcium to aluminium molar ratio and/or amino acid to aluminium molar ratio lead to compositions of higher Band III content (vide infra) and, in general, higher antiperspirancy performance. It will be noted that higher Band III content is generally indicative of higher antiperspirancy performance.

Preferred amino acids for use in the present invention are glycine, alanine, valine and proline. A particularly preferred amino acid for use in the present invention is glycine.

The presence of the water-soluble calcium salt and amino acid lead to activation of the antiperspirant salt, by which is meant an increase in its Band III content (vide infra).

In preferred embodiments, an aqueous solution of the antiperspirant salt is heated with the water-soluble calcium salt and glycine to achieve activation.

The content of “Band III material” in an antiperspirant salt may be determined by SEC (Size Exclusion Chromatography) analysis. The SEC technique is well known in the art and is described in further detail in US 4,359,456 (Gosling). The SEC band commonly referred to as Band III is designated as “Peak 4” in EP 1,104,282 B1 by Gillette.

Herein, “Band III content” refers to the integrated area in the Band III region of the SEC chromatograph relative to the total integrated area in all of the regions corresponding to aluminium species; that is to say, Bands I, II, III, and IV.

In preferred embodiments of the invention, compositions according to the invention have an AP active having a Band III content of at least 30% and more preferably at least 50%. The AP active used in the present invention is preferably a “milled” active, meaning that it has been ground down, typically to a relatively fine powder, and often following spray drying of an aqueous solution of the active. The milling produces an active that comprises non-hollow particles and this is a preferred feature of the invention, as it can aid in reducing white marks [see EP 2,999,452 B1 (Unilever, 2017)]. It is preferred that the AP active has an Rl of from 1.52 to 1.57, more preferably 1.53 to 1.55 and most preferably about 1.54.

The milled AP active, when employed, preferably has a mean particle size (D50) of at least 6 microns, preferably from 6 to 25 microns, and more preferably from 7 to 15 microns.

Herein, mean (D50) particle sizes may be measured using (laser) light scattering techniques, for example using a Mastersizer instrument, obtainable from Malvern Instruments. Such instruments are set to produce a volume plot and a lens is selected in accordance with the maker's instructions to accommodate the expected particle size distribution, (or various lenses can be tested until the best lens is identified). Measurements are made by methods known in the art.

Herein, references to amounts of the AP active, including ratios relative thereto, refer to ASCH present as an anhydrous solid, i.e. excluding any water of hydration associated with the active, and also excluding the water-soluble calcium salt and the amino acid present in the composition and/or associated with the AP active.

The AP active is present in the composition at less than 30%, preferably less than 25% and, in compositions giving especially low marks, less than 20%, all figures excluding any propellant that may be present therein.

In order to achieve good to excellent AP efficacy, it is also important not to have too little AP active present. Hence, the level of AP active is preferably from 5 to 30%, more preferably from 10 to 30% and further preferably from 12 to 25%, all figures excluding any propellant that may be present therein. For compositions giving especially low marks, the most preferred level is from 12 to 20%, again excluding any propellant that may be present therein.

In compositions comprising a propellant, the amount of AP active may alternatively be described relative to the total composition, including all components thereof. In such compositions, the AP active is present in the composition at a preferred level of less than 6%, more preferably less than 5% and, in compositions giving especially low marks, less than 3%

Herein, the carrier oil is a liquid material that is non-miscible with water. It is free from volatile cyclic silicone oil and comprises a C12-C16 branched chain alkane having a refractive index within 0.13 of that of the AP active.

Herein, volatile cyclic silicone oils and volatile silicones should be understood to be silicone oils having a vapour pressure of greater than 1 Pa at 25°C.

The absence of volatile cyclic silicone oil is essential for many reasons, including environmental benefits. It is preferred that compositions according to the invention are free from all volatile silicone oils and, more preferably, free from all silicone oils. By avoiding silicone oils, the biodegradability of the composition may be increased.

The carrier oil comprises a C12-C16 branched chain alkane having a refractive index within 0.13 of that of the AP active. This feature enhances the sensory benefits and reduced staining benefits of the present invention. Typically, the C12-C16 branched chain alkane has a refractive index of greater than 1.41.

In preferred embodiments, the C12-C16 branched chain alkane is reasonably nonvolatile, i.e. , it has a reasonably low vapour pressure. This enhances retention on the skin surface and the ability of the oil to help with reduced staining. It is preferred that the C12- C16 branched chain alkane has a vapour pressure of less than 0.6 hPa (0.6 mbar), more preferably less than 0.4 hPa and most preferably less than 0.3 hPa, all at 20°C. In preferred embodiments, the C12-C16 branched chain alkane is a C14-C16 branched chain alkane.

In other preferred embodiments, the carrier oil comprises a C12-C16 branched chain alkane selected from isododecane and/or isohexadecane. Isododecane has an Rl of 1.419 and a vapour pressure of 1 hPa at 20°C. Isododecane has an Rl of 1.439 and a vapour pressure of 0.1 hPa at 20°C. Isohexadecane is particularly preferred. These oils have good sensory properties and are effective in achieving low white marks. In addition, it has been found that compositions comprising such oils have good rheological stability characteristics, particularly before the addition of any propellant that might be employed.

In preferred embodiments, isohexadecane is the predominant oil in the carrier oil. By “predominant”, it is meant that this oil is present in a higher amount than any other single oil.

In preferred embodiments, isohexadecane comprises greater than 35% by weight of the oils present in the carrier oil.

Isododecane has an Rl of 1.419 and isohexadecane has an Rl of 1.439. By contrast, cyclopentasiloxane has an Rl of 1.396. Assuming an Rl for the AP active of 1.54, the Rl for isohexadecane differs from this by 0.101 , the Rl of Isododecane differs from this by 0.121 and the Rl of cyclopentasiloxane differs from this by 0.144. These differences are critical when it comes to white mark reduction.

A preferred additional component of the carrier oil is an ether oil, preferably an ether oil having an Rl within 0.13 of AP active being employed. An especially preferred ether oil is PPG-butyl ether, which has an Rl of 1.446.

In some preferred embodiments, an ester oil is also employed, especially in compositions also comprising an ether oil. When employed the ether oil preferably has an Rl within 0.13 of AP active being employed. A particularly preferred type of ester oil is an alkyl ether of an aryl group, such as 012-015 alkyl benzoate. Another type of ester oil used in certain preferred embodiments are triglycerides of unsaturated fatty acids. These oils are typically natural oils and are biodegradable. Herein, a “triglyceride of an unsaturated fatty acid” should be understood to mean a triglyceride wherein at least 50% of the fatty acids contain at least one double-bond. Such triglycerides are typically mixtures of glycerol esters with different fatty acids. A preferred oil of this type is Helianthus Annuus seed oil, otherwise known as sunflower seed oil.

Another carrier oil component that may be used is a C16-C20 branched chain fatty alcohol, such as octyldodecanol.

Table 1 details examples of suitable carrier oils for use in accordance with the invention, together with their Rl values.

The carrier oil as a whole preferably has a weighted mean refractive index within 0.13 of that of the AP active. This helps with achieving reducing white marks transferred to clothing (vide supra).

The weighted mean refractive index of the carrier oil as a whole is preferably from 1.42 to 1.54 and more preferably from 1.43 to 1.54.

Table 1

The carrier oil as a whole and the components thereof preferably have good sensory properties. This can be important to consumers during and/or after topical application of the composition. The carrier oil is present in the composition, excluding any propellant that may be present therein, at a preferred level of at least 50%, more preferably at least 55%. In compositions particularly aimed at giving reduced white marks, this level is preferably at least 60% and more preferably at least 65%. In order to maintain space in composition for the antiperspirant active, it is preferred that the carrier oil is present at up to only 70%, or for compositions particularly aimed at giving reduced white marks, up to 75% or 80%.

A propellant is not an essential component of compositions of the invention because an aerosol may be created purely by mechanical means, such as pump spray or squeeze spray mechanism. However, a propellant is a preferred feature of many embodiments of the invention.

When employed, the propellant may be a liquified gas, a pressurised gas such as nitrogen or any combination thereof.

Suitable liquified gases suitable for use as propellants used with the present invention include propane, butane, isobutane, DME, and hydrofluorocarbons, such as difluoroethane, otherwise known by the INCI name of HFC152a. Preferred propellants are mixtures of propane, butane and isobutane or mixtures of one or more hydrofluorocarbons (difluoroethane being preferred) and C3 to C4 alkanes.

When a propellant is employed, it is preferably used at a level of from 50%, more preferably from 65% and most preferably at from 80% of the total composition. Suitable ranges of inclusion of propellant are from 50 to 95%, more preferably from 65 to 95%, and most preferably from 80 to 95% of the total composition. Such preferred minimum amounts and ranges can assist with the reduced white marks benefit of the present invention.

A preferred additional component for use in compositions of the present invention is a fragrance or fragrance oil, sometimes alternatively called a perfume (oil). The fragrance oil may comprise a single fragrance or component more commonly a plurality of fragrance components. Herein, fragrance oils impart an odour, preferably a pleasant odour, to the composition. Preferably, the fragrance oil imparts a pleasant odour to the surface of the human body the composition is applied to the same.

The amount of fragrance oil in the total composition is preferably up to 3%, advantageously is at least 0.5% and particularly from 0.8% to 2%.

The amount of fragrance oil in the composition, excluding any propellant that may be present therein, is preferably up to 20%, advantageously is at least 4% and particularly from 6% to 15%.

A suspending agent is a highly preferred component of compositions of the invention, particularly those also comprising a propellant. Such agents aid the suspension of the AP active in the composition. Preferred suspending agents are clays, particularly hydrophobically-modified clays. Particularly preferred are hydrophobically modified hectorite or bentonite clays and especially preferred is disteardimonium hectorite (e.g. Bentone 38V, ex 20 Elementis).

The suspending agent is typically employed at from 0.1 to 1.5% by weight of the total composition.

When a suspending agent is present, in particular a clay-based suspending agent, it is preferred that an activator for the suspending agent is also present. The activator serves to improve the performance of the suspending agent. Preferred activators are triethyl citrate and propylene carbonate. Propylene carbonate is especially preferred.

The activator is preferably used at a level of from 0.01 to 0.25% of the total composition.

Yet other optional ingredients can include sensory modifiers, such as talc or finely divided polyethylene, such as in an amount of up to 3% by weight of the base composition; colorants, by way of non-limiting example in a proportion of up to 0.5% of the base composition; skin cooling agents such as menthol often selected in an amount of up 0.5%, particularly up to 0.2% of the base composition, and wash-off agents such as non- ionic surfactants, and particularly polyethoxylated fatty alcohols or acids, for example in an amount of up to about 3% of the base composition.

The method of manufacture involves multiple steps; in particular, steps involved in the manufacture of the AP active and steps involved in its formulation.

In preferred embodiments, the ASCH is first activated by heating it in aqueous solution with a water-soluble calcium salt and an amino acid. Calcium chloride and glycine may be used as the water-soluble calcium salt and the amino acid in this step. The aqueous mixture is typically heated to an extent to achieve a Band III content of at least 55%. The aqueous mixture may be heated to a temperature of greater 70°C for greater than 3 hours.

Following the activation step described immediately above, the aqueous solution is typically spray dried. This is preferably done using rotary atomisation.

Following the spray drying, the AP active is milled, preferably to give a mean particle size (D50) of from 6 to 25 microns, and more preferably from 7 to 15 microns.

The milled AP active is formulated into the aerosol composition by first mixing it with the carrier oil and, typically, a suspending agent such as a bentonite clay. This is preferably done using a high shear mixer. An “activator” for the suspending agent is also generally added. Propylene carbonate is a preferred activator. This produces the “base” composition which, in compositions comprising a propellant, is subsequently gassed by the addition of the propellant to give the final composition.

Fragrance is preferably added to compositions according to the invention. In some preferred embodiments, this is done immediately before the base is gassed with the propellant. The base (plus or minus propellant) may often be stored for several days before fragrance and propellant are added. It is desired that the base has sufficient viscosity stability to be still usable after storage for up to 7 days at ambient temperature. A preferred method of manufacture combines some or all of the processes described in the above paragraphs.

Examples

The Examples described in Table 2 were prepared by a method consistent with each of the preferred manufacturing steps described hereinabove. In particular, the base composition minus fragrance was prepared first and fragrance and propellant were added at a later date, following stability trails on the base (minus fragrance).

The amounts indicated for the components of the each of the Examples are shown relative to the “base” (minus the fragrance) in the first column, and relative to the total composition, in the second column. Table 2 * Activated aluminium sesquichlorohydate comprising 64% anhydrous ASCH, 17.18% glycine, 8% calcium chloride and water of hydration associated with the ASCH. Hence, the anhydrous ASCH base content of the Examples was:

• Example 1 : 24.00% • Example 2: 15.69% and

• Example s: 15.59%.

** The propellant was a blend of propane, butane and isobutane.

Rheological stability trials were performed on each of the base compositions as indicated (i.e. minus the fragrance) and these were successful for up to 7 days for each of samples tested, no unacceptable increase in viscosity being observed.

A study of white marks produced by a formulation according to invention vs. white marks produced by a formulation comprising a cyclic volatile silicone (cyclopentasiloxane) instead of isohexadecane was performed using the base compositions detailed in Table 3, each of which was gassed with the same level of the same propellant (a blend of propane, butane and isobutane).

Table 3 The compositions were sprayed onto black cloths from the same distance and using the same spray duration. Example 1 produced greatly reduced white marks when compared with Comparative Example A.

Claims

1. An essentially anhydrous antiperspirant (AP) aerosol composition comprising less than 1% by weight of water; said composition comprising an AP active which is aluminium sesquichlorohydrate activated by a water-soluble calcium salt and an amino acid, and a carrier oil which is free from volatile cyclic silicone oil and which comprises a C12-C16 branched chain alkane having a refractive index within 0.13 of that of the AP active, wherein the aluminium sesquichlorohydrate is present at less than 30% by weight of the composition, excluding any propellant that may be present therein.

2. A composition according to claim 1 , wherein the AP active is a milled active.

3. A composition according to claim 2, wherein the AP active comprises non-hollow particles.

4. A composition according to any one of the preceding claims, wherein the AP active is present at less than 25% by weight of the composition, excluding any propellant that may be present therein.

5. A composition according to any one of the preceding claims, comprising a propellant which comprises butane, isobutane and propane.

6. A composition according to any one of the preceding claims, wherein the carrier oil comprises an ether oil.

7. A composition according to any one of the preceding claims, wherein the carrier oil comprises an ester oil.

8. A composition according to claim 7, wherein the carrier oil comprises a triglyceride of an unsaturated fatty acid.

9. A composition according to any one of the preceding claims, wherein isohexadecane is the predominant oil in the carrier oil.

10. A composition according to any one of preceding claims, comprising a suspending agent for the AP active.

11. A composition according to any one of the preceding claims, which is free from volatile silicone oil.

12. A composition according to any one of the preceding claims, wherein the particle size of the AP active [D50] is from 6 to 25 microns.

13. A composition according to any one of the preceding claims, wherein the carrier oil has a weighted mean refractive index within 0.13 of that of the AP active.

14. A non-therapeutic method of achieving a reduction in perspiration from the human body comprising the topical application of an anhydrous AP aerosol composition according to any one of the preceding claims.

15. A method of manufacture of an anhydrous antiperspirant aerosol composition comprising the steps of:

(i) heat activation of aluminium sesquichlorohydrate in aqueous solution with a water-soluble calcium salt and an amino acid;

(ii) spray-drying of the aqueous solution resulting from step (i);

(iii) milling the dried AP active resulting from step (ii);

(iv) mixing the milled AP active resulting from step (iii) with a carrier oil which is free from volatile cyclic silicone oil and which comprises a C12-C16 branched chain alkane having a refractive index within 0.13 of that of the AP active; and

(v) gassing the base composition resulting from step (iv) with a propellant to give an aerosol composition; wherein the aluminium sesquichlorohydrate is present at less than 30% by weight of the composition, excluding the propellant present therein.