Moisture Resistant Perfuming Microcapsules Comprising a Water-Soluble Resin

Technical Field and Brief Description of the Invention

The present invention relates to the field of perfumery. It concerns more particularly perfuming microcapsules characterised by the fact that, when subjected to water, they dissolve rapidly therein to release the encapsulated material, whilst resisting high moisture conditions during storage.

A major but not limiting application for such microcapsules are hand-wash powder detergents. When the detergent is added to cold water, the perfuming microcapsules dissolve faster than the powder detergent thus allowing the perfume to quickly get released into the air before it becomes emulsified by the dissolving detergent.

This effect is called blooming and distinguishes encapsulated perfume from spray-on perfume (i.e. liquid perfume sprayed onto the powder detergent but not prior encapsulated).

However, it is common for such capsules to be very sensitive to moisture or humidity.

The present invention concerns water-soluble perfuming microcapsules that, when subjected to increased relative air humidity (hereinafter designated as relative humidity and indicated as RH) during storage, remain intact and do not release the encapsulated perfume during usual storage periods.

Furthermore, the present invention concerns water-soluble perfuming microcapsules that, when subjected to water or body sweat, dissolve slowly and provide a retarded release of the encapsulated perfume. A major but not limiting application for such microcapsules with retarded release are water-free antiperspirant sprays.

In another aspect, the present invention also concerns perfuming microcapsules characterised by the fact that, when subjected to a sufficiently powerful ignition source, their rapid combustion reaction is weak or moderate. In fact, the microcapsules of the invention comprise an effective amount of film-forming resin which does not only stabilize the microcapsules against strong air humidity, but also functions as explosion suppressant, susceptible of reducing the violence of microcapsule powders explosion, so as to allow classification of these particles in a dust hazard class St-I.

Background of the Invention and Problems to be Solved

Microcapsules are employed to a large extent in the perfumery and flavouring industries. They constitute delivery systems for perfuming ingredients and can be advantageously used in a very large number of applications. The encapsulation of active substances such as perfuming ingredients provides protection of the ingredients there- encapsulated against "aggressions" such as oxidation or moisture and allows certain control of the kinetics of the fragrance release and the possibility of inducing sensory effects on the user through sequential release of fragrances.

Now, the numerous advantageous properties of using this type of microcapsules for example in the perfume industry are somewhat reduced by problems related to their manufacture, transportation, storage and handling. In fact, such delivery systems, due to their nature, and in particular to the fact that they need to dissolve fast in cold water, form readily water-dissolvable mixtures which can already soften or dissolve in humid powder detergents or in packaging that is exposed to high air humidity.

Spray-drying of perfumes or flavors is carried out from aqueous emulsions. Spray-dried perfumed capsules are generally prepared from a water-insoluble perfume with ingredients of log P value higher than 2.5 and a water soluble matrix, preferably modified polydextrose, and starch derivatives.

The present applicant has been a manufacturer of such perfumed powders for many years, under the commercial tradename of Fircaps ^® , and more details on such microcapsule preparation can be found in its earlier patent documents, such as US patent 4,803,195, US patent 5,508,259 and International publications WO 03/043728 and WO 2006/038134. The resulting capsules are delivery systems which differ from core- shell capsules in that the perfume is homogeneously distributed within the water-soluble matrix.

In order to avoid great perfume loss during spray- drying it is also well known to the person skilled in the art that the solubility parameters of the perfume have to differ strongly from those of the matrix. The microcapsules are obtained by spray-drying of prior prepared emulsions which are admixtures of perfume, water and the carrier or matrix material, preferably a self-emulsifying starch such as octenylsuccinated starch (commercialized under the tradename Capsul ^® from National Starch).

Such spray-dried capsules easily release the encapsulated perfume through contact with humidity or water and they have been taught to be useful, amongst other, in deodorant and antiperspirant type products, intended for topical application and capable of releasing the fragrance upon repeated moisture activation and re-encapsulation thereof, upon the user's perspiration periods.

In a relatively recent document published by A. Shefer et al. as US 2003/0194416, there are also described capsules of this type, mainly based on film-forming polyvinyl alcohol matrices, possibly admixed with starches. The inventors stress the importance of carefully selecting the type of perfume that can be encapsulated in this type of spray- dried perfume emulsions, to avoid leakage thereof during storage, but do not otherwise add any pertinent material to the already vast literature in this field, or otherwise solve the problems that spray-dried perfume powders still pose to the skilled manufacturer.

The aim of the present invention is to provide spray-dried perfume powders that deal with those problems and improve upon this vast prior art. It is in fact generally desired that such spray-dried microcapsules are capable of better resisting storage conditions common for the consumer products to which they are added, in particular powder detergents for laundry or other surface treatments. In particular, in Asian countries where the relative air humidity can reach 70% or more, and where the packaging of the powder detergent is not always a very efficient protective barrier against such air humidity, the spray-dried capsules can soften or even dissolve upon storage and release the encapsulated perfume before the consumer uses the consumer product.

The perfume microcapsules according to the present invention provide a system for the carriage and delivery of the fragrance which shows an improved resistance to moisture and effectively solves this problem in a more advantageous manner, whilst preserving all the properties of the fragrance delivery systems of this type prior taught by the applicant, in particular in the more recent WO 03/043728 and WO 2006/038134 publications. The latter address another important problem in the handling of perfume powders manufactured by spray-drying techniques and provide solutions to the problems inherent to the use of microcapsules comprising volatile substances and which constitute combustible dusts that can, when dispersed in air or another oxygen-containing gas, form readily ignitable mixtures. When ignited by a sufficient powerful ignition source, the result is a rapid combustion reaction with advancing pressure and flame front.

This issue becomes important during the preparation of microcapsules. In particular, spray-drying and fluidised-bed encapsulation processes are highly concerned by this issue, as they are both based on the use of an equipment wherein particles are suspended in hot air as fine particles and can therefore undergo explosion during their preparation. Spray-drying is in fact the most common encapsulation technique used to stabilise volatile substances such as flavours or fragrances, and convert them into a solid form, suited to many applications. Spray-dried powders are commonly made in an usual spray-drying equipment resorting to the use of rotating discs or multi-component nozzles. Detailed techniques are described for instance in K. Masters, Spray-drying Handbook, Longman Scientific and Technical, 1991.

Both the above-described encapsulation equipments being susceptible to explosion of particles suspended in the air, they thus have to be adapted as a function of the technical safety parameters characterising the particles there-treated. In particular, they have to be dimensioned as a function of the violence of the explosions susceptible of occurring during the preparation of the microcapsules. Therefore, the problem of reducing the violence of possible explosions of powder products resulting from such encapsulation processes is of paramount importance for the industry.

For the safe handling of combustible substances, it is imperative to know the dangerous properties of a product. The reliable way to characterise the combustible and explosive properties of a product is to subject a sample of the product to various tests and classify the results in accordance with the technical safety characteristics. The international standards (VDI Guideline 2263 part 1 : Dust Fires and Dust Explosions, Hazard Assessment - Protective Measures, Test Methods for the Determination of Safety Characteristics of Dusts, Beuth, Berlin, May 1990) describe the test equipments (Modified Hartmann apparatus and Close apparatus, 20-litre sphere apparatus) and methods, namely the ISO standard procedure ISO 6184/1. These methods allow to determine physical constants such as the maximum explosion behaviour of a combustible dust in a closed system. A pyrotechnic igniter with a total energy of 10 kJ is used as ignition source. From test methods described in the mentioned guidelines, a characteristic constant, K_st, which is dust specific, is determined. As there are so many such dusts produced and processed in industrial practice, for example for pharmaceutical and cereal, flour products, it is appropriate to assign this maximum explosion constant to one of the several dust explosion classes and to use these as a basis for the dimensioning of

constructional protective measures. The correspondence between these classes hereafter referred as dust hazard classes, and the constant K_st is the following :

Dust Hazard Class Product Specific Constant K ₁ St [bar.rn.s ^~1 ] St-I O to 199 St-2 200 to 299 St-3 > 300

Now, although some perfuming and flavouring ingredients are classified in a dust hazard class St-I, a large number of these ingredients, and thus the microcapsules encapsulating them, are still classified under an St-2 dust hazard class and thus require production equipments specifically adapted to the violence of possible explosions, which of course can be very costly. The problem is all the more important, the more volatile the fragrances handled. As above-mentioned, International patent publications WO 03/043728 Al and

WO 2006/038134 Al, to the present applicant, disclose perfuming microcapsules having fireproofing or fire-hazard reducing agents dispersed in or absorbed within a polymeric carrier material, these agents being inorganic salts or short-chain organic acids or their salts. In spite of the advantages of using such fireproofing agents, there is a need for constant improvement in this field and substances suitable as explosion suppressants having further beneficial properties are very much in demand. There is in particular a need to find more efficient explosion reduction agents, which can be used with similar efficiency as the prior taught ones but in smaller amounts, and there is a need for fireproofing agents that have a beneficial effect on the hygroscopicity of the perfuming powder microcapsules and that compare advantageously with those taught in the prior art, namely those disclosed in WO 03/043728 and WO 2006/038134 are not always suitable for use in high humidity bases as these fireproofing agent are often plasticizers that enhance the hygroscopicity of the perfuming microcapsules.

The present invention provides an unexpectedly advantageous solution to the problems above-mentioned encountered upon the manufacture, handling, storage and use of spray-dried solids carrying volatile substances.

Description of the Invention

A first approach to increase humidity resistance of such spray-dried capsules would be the addition of water-insoluble ingredients to the matrix such as waxes or latex, which is a water dispersed resin of a water-insoluble polymer, mainly polyacrylate. However, when such water-insoluble products are added to the emulsion of perfume, matrix and water, the solubility parameter between perfume and matrix become too similar, resulting in poor encapsulation of the perfume (see Example VII). Furthermore, we have been able to establish that polyvinylalcohol, and mixtures of polyvinylalcohol and modified starch, used as the encapsulation matrix, could reduce the hygroscopicity of the resulting perfuming microcapsules, but the volatile perfume was not well retained in the matrix. Upon ageing at elevated humidity and temperature, the microcapsules did not dissolve but the encapsulated perfume diffused out off the capsule (see Example IV and

V). Surprisingly, we have now been able to establish that the novel addition of carefully selected water-soluble film-forming resins, in effective amounts, to the perfume microemulsions intended to be spray-dried into a solid form, made it possible to reduce the hygroscopicity of the fragrance microcapsules obtained, when exposed to high moisture environments, in particular 70% or more relative air humidity. The present invention thus provides spray-dried perfuming microcapsules comprising at least one perfuming ingredient dispersed in or adsorbed within a moisture- sensitive carrier matrix, namely of modified starch, characterised in that the microcapsules further comprise an effective amount of a water-soluble, film-forming resin capable of reducing the hygroscopicity of the spray-dried microcapsule powders, relative to those lacking such film-forming resin.

As the moisture-sensitive carrier material, it can be selected from the group consisting of cellulose, cellulose derivatives, starch and starch derivates. Particularly advantageous carrier materials are starches, and more preferably, the octenylsuccinate modified starch available under the tradename CAPSUL ^® (National Starch, USA). The invention relates namely to the microcapsule powders wherein the water- soluble, film-forming resin is selected from the group consisting of melamine/formaldehyde and urea/formaldehyde resins, and copolymers of maleic anhydride and/or maleic acid with acrylic acid. A copolymer of maleic acid and acrylic

acid, and preferably the commercial products available under the tradename Sokalan ^® CP 45 (origin: BASF), are water-soluble film-forming resins or polymers particularly suited to the manufacture of microcapsules of the invention. Preferred melamine- formaldehyde resins according to the invention are those commercialized under the tradename Urecoll ^® (origin: BASF). The use of water-miscible amino-based compounds such as solid melamine or melamine VFR50 (origine: Corvus) is also convenient.

In particular, such water-soluble film-forming resins, when added at a relative weight comprised between 0.5% and 20%, and more preferably between 0.5 and 12.0% weight, relative to the dry weight of microcapsules, did not reduce the capability of the latter to encapsulate perfume and their ability to quickly dissolve in water and thus provide an instant fragrance blooming effect in the presence of moisture. When such water-soluble, film-forming resins are added in higher amounts, i.e. at a relative weight higher than 8.0% of the dry weight of microcapsule, a retarded dissolution of the microcapsules in water, or when in contact with for example body sweat or other sources of moisture, was observed which resulted in a retarded release of the encapsulated perfume, and thus the possibility of controlling the release of the latter in time.

Moreover, it was also found that certain water-soluble resins had an advantageous effect as explosion suppressant agents to the microcapsules, effective to reduce the violence of possible explosions during their preparation, in particular when suspended in hot air. The K_st constant of microcapsules comprising these resins could thus be effectively reduced.

The invention further provides perfumed consumer products containing the microcapsules in an amount sufficient to impart to the consumer product a perceptible fragrance when in contact with a source of moisture.

The perfuming microcapsules of the invention thus comprise an effective amount of a water-soluble, film- forming resin which is capable of reducing the hygroscopicity of the microcapsules, such that the microcapsules do not release their encapsulated perfume when stored up to three months at a relative air humidity of 70%. In some cases, the presence of the water-soluble, film- forming resin also allowed a reduction of the risk and violence of explosion of the spray-dried powders, possibly induced by their suspension in the air during their preparation. This is very advantageous considering that such delivery systems are mainly composed of highly volatile

ingredients which constitute therefore combustible dusts. Such volatile ingredients had to be used in the past in limited proportions in compositions subjected to processes involving the suspension of particles in hot air. Now, the solution provided by the present invention allows to use higher quantities of these ingredients, and therefore provides an advantageous alternative to the prior use of precursors of certain particularly volatile ingredients.

The invention therefore provides an advantageous solution as regards the problem of the preparation of perfuming and flavouring microcapsules and powder products, in particular for preparations via processes involving a spray-drier or a fluidised bed, wherein fine particles are suspended in the air and are therefore more susceptible of exploding. Under an St-I class, the violence of the explosion will be a weak or at least moderate reaction, whereas it would be a strong reaction for a dust hazard class St-2, and a very strong reaction for a dust hazard class St-3. As a consequence, the equipment used for the preparation of microcapsules according to the present invention can be dimensioned accordingly, i.e. as St-I and thus become less costly, whilst guarantying the same or better manufacture safety conditions, and providing capsules which are more resistance to high humidity storage conditions.

The invention provides a new approach to obtaining high water humidity resistance of water-soluble spray-dried perfuming microcapsules by addition of water- soluble melamine-based compounds or resins that can form a film after spray-drying thus protecting the matrix from fast dissolution upon exposure to significant air humidity. Examples of water-soluble resins are, copolymers of maleic acid or maleic anhydride and acrylic acid (Sokalan ^® CP 45, Sokalan ^® CP 125 from BASF), sodium salts of copolymer of maleic acid and acrylic acid (Sokalan ^® CP 5 from BASF), melamine or urea-based resins such as Urecoll SMV (melamine/formaldehyde resin from BASF), and their mixtures. Other useful melamine-based compounds are solid melamine or melamine VFR50 (mixture of melamine, uree and blanose (thickener); origin: Corvus). Such water- soluble resins have been found to be fully compatible with the water-soluble starch matrices used according to the invention for example, and with a broad range of perfuming compounds and compositions, thus not interfering with the efficient encapsulation of the perfume. Moreover, the delivery systems of the invention make it possible to encapsulate any kind of perfume material and thus dispense with the special choice of perfume materials that prior known disclosures resorted to in order to improve

the stability upon storage of the microcapsules against unwanted loss of the perfume encapsulated in the powders, such as described in US 2003/0194416 for example.

In addition, it was now been unexpectedly established that the use of copolymers of acrylic acid, in particular the copolymer of maleic acid and acrylic acid Sokalan ^® CP 45 (from BASF), in the perfume carrier matrices according to the invention, also positively affected the explosivity of the resulting spray-dried powders in a manner making it possible to reduce, or totally eliminate, the use of significant amounts of explosion suppressants such as those described for example in WO 03/043728, WO 2006/038134, and other functionally equivalent agents. In particular embodiments of the present invention, the microcapsules comprise from 0.5 to 40% by weight of water-soluble, film- forming resin relative to the dry weight of the microcapsule. Preferably, the microcapsule comprises 1 to 20%, and most preferably 2 to 12% by weight of water-soluble resin, relative to the dry weight of the microcapsule. As previously mentioned, when such water-soluble, film-forming resins are added in higher amounts, i.e. at a relative weight higher than 8.0% of the dry weight of microcapsule, a retarded dissolution of the microcapsules in water, or when in contact with for example body sweat or other sources of moisture, was observed which resulted in a retarded release of the encapsulated perfume, and thus the possibility of controlled the release of the latter in time. The microcapsule of the invention is based on the presence of at least one perfuming material and a polymeric carrier material.

The perfuming ingredient, in the form of one sole ingredient or in the form of a composition or mixture of perfuming ingredients, either in isolation or, optionally, in a solution or suspension in solvents and adjuvants of current use in perfumery, represents from 1 to 70%, and preferably from 15 to 60%, most preferably 20 to 45% by weight of the total weight of the microcapsules.

The terms "perfume ingredient" or "perfume composition" as used herein are deemed to define a variety of fragrance materials of both natural and synthetic origins. They include single compounds and mixtures. Specific examples of such components may be found in the current literature, e.g. in Perfume and Flavour Chemicals by S. Arctander, Montclair, N.J. (USA); Fenaroli's Handbook of Flavour Ingredients, CRC Press or Synthetic Food Adjuncts by M. B. Jacobs, van Nostrand Co. Inc., and other similar text books; and are well-known to the person skilled in the art of perfuming,

and/or aromatising consumer products, i.e. of imparting an odor to a consumer product or modifying its odor.

They encompass ingredients of current use in the fragrance industry and are typically volatile or labile ingredients in liquid form, preferably with a log P in the range of -2 and 7, preferably 2 - 6. Natural extracts can also be encapsulated into the system for perfuming consumer end products. Examples of these include, amongst others, citrus extracts such as lemon, orange, lime, grapefruit, or mandarin oils.

Other examples of fragrance active ingredients are synthetic fragrance oils, flavouring, essential oils, oleoresins and other extracts derived from plants, for example from leaves, flowers, fruits, roots, rhizomes, stem, and so forth.

The term fragrance also includes compounds and compositions such as cooling, refreshing, pungent, tingling and hot/spicy compounds of current use in fragrances, or yet ingredients which are useful to suppress malodor of a large variety of origins, such as toilet or kitchen malodor, animal or human malodor, tobacco malodor in rooms, textiles or other surfaces, etc.

A typical characteristic of fragrance ingredients susceptible of being spray dried is the high proportion of volatile compounds and/or components. Accordingly, it may comprise at least 10 wt.%, preferably at least 20 wt.%, or even 30 wt.% or 40 wt.% of chemical compounds having a vapour pressure of > 0.007 Pa at 25°C. Preferably, at least 10 wt.% have a vapour pressure of > 0.1, more preferably, at least 10 wt.% have a vapour pressure of > 1 Pa at 25°C, and most preferably, at least 10 wt.% have a vapour pressure of > 10 Pa at 25°C. The value of 0.007 Pa at 25°C is selected because it encompasses many compounds used by the skilled perfumer. Compounds meeting these criteria are generally regarded as having a volatile character. The lower limit of 10 wt.% of such highly volatile compounds is regarded as being a substantial of the fragrance compositions that can be encapsulated according to prior known spray drying processes.

For the purpose of the present invention and for the sake of convenience, the vapor pressure value is determined by calculation. Accordingly, the method disclosed in "EPI suite"; 2000 U.S. Environmental Protection Agency, is used to determine the concrete value of the vapour pressure of a specific compound or component of the active ingredient. This software is freely available and is based on average values of vapour pressures obtained by various methods by different scientists.

According to the present invention, the perfume ingredient or composition is dispersed in a carrier or matrix material.

Preferably, the carrier material comprises carbohydrates. For example, the carrier material comprise mono-, oligo- and/or polysaccharides, wherein the prefixes oligo- and poly are as defined below.

In an embodiment of the present invention, the carrier material comprises a monomeric, oligomeric or polymeric carrier material, or mixtures of two or more of these. An oligomeric carrier is a carrier wherein 2-10 monomeric units are linked by covalent bonds. For example, if the oligomeric carrier is a carbohydrate, the oligomeric carrier may be sucrose, lactose, raffϊnose, maltose, trehalose, fructo-oligosaccharides, to name a few examples only.

Examples of a monomeric carrier materials are glucose, fructose, mannose, galactose, arabinose, fucose, sorbitol, mannitol, for example.

Polymeric carriers have more than 10 monomeric units that are linked by covalent bonds. Non limiting examples of the latter include polyvinyl acetate, polyvinyl alcohol, dextrines, maltodextrines, natural or modified starch, vegetable gums, pectins, xanthanes, alginates, carragenans or yet cellulose derivatives such as for example carboxymethyl cellulose, methylcellulose or hydroxyethylcellulose, and generally all materials currently used for encapsulation of volatile substances. More preferably, the matrix component comprises a starch derivative. This group of polysaccharides itself includes many different polymers since it is possible to modify the starch either by mechanically damaging the starch granules (grinding or extrusion), by heating with or without an acid or a base to pre-gelatinise or degrade the starch and to get thin- or thick- boiling starch, dextrins or maltodextrins of various molecular weights. Other possible modifications of starch and resulting derivatives include octenyl-succinated starch, starch ethers (i.e. carboxymethyl starch), starch esters (i.e starch monophosphate), crosslinked starch and/or oxidised starch.

Preferably, the polymeric carrier is modified starch, such as, for example, octenylbutanedioate modified starch (HiCap ^® or Alcocap ^® from National Starch) and more preferably octenylsuccinated starch sold under the tradename Capsul ^® by National Starch.

According to another aspect, the present invention provides a method for the preparation of perfuming microcapsules as described above. There are several

alternatives to the method for the preparation of the microcapsules of the invention. In a first embodiment, the water-soluble resin, in particular a copolymer of maleic acid with acrylic acid, and more particularly Sokalan ^® CP 45, is added to an aqueous emulsion consisting of the perfuming ingredient or composition dispersed in the polymeric carrier material, in particular Capsul ^® . A small amount of pH regulating agent, typically an acid such as citric acid, is added to the Capsul ^® (origin: National Starch) as recommended by the suppliers of this product to lower the pH. The usual amount of citric acid is typically comprised between 1.0 and 5 weight %, more preferably between 2.5 and 5%, but the skilled person is able to vary this amount as a function of the emulsion's properties. The obtained emulsion is then spray-dried in order to form a powder. Optionally, an emulsifier and an explosion suppressing or reducing agent other than the resin above- mentioned may be added to the initial emulsion.

This encapsulation technique does not require a more detailed description herein, as it relies on conventional spray-drying techniques, which are perfectly well documented in the prior art [see for example Spray-Drying Handbook, 3 ^rd ed., K. Masters; John Wiley (1979)] and currently applied in the food industry or in the flavour and perfume industries.

The microcapsules of the invention have an average diameter varying from usually 5 to 800 μm, more preferably 50 to 300 μm. The present invention also provides a method for reducing violence of explosion of a powdered perfuming composition. Violence of explosion is determined by the K_st constant described above. The water-soluble resin as the explosion suppressant or reducer can be directly added to the spray-dried powder. However, any way of dry- or wet-adding of the explosion suppressant to a powdered composition is encompassed. For example, the addition may be via dry-blending or dry-mixing with the components of the powdered composition. Alternatively, the explosion suppressant may be incorporated in and/or within the particles of a powdered composition. This step may be performed by adding the explosion suppressant to an aqueous emulsion dispersed in a polymeric carrier material as described above, followed by drying the obtained emulsion, for example by spray drying.

In a further alternative, the explosion suppressant may simply be coated onto a powdered composition. The coating may be performed by coating onto a porous

polymeric carrier material, for example with a fluidised bed apparatus, as discussed above, for example.

The microcapsules of the invention can be advantageously used in all the fields of modern perfumery to positively impart, improve, enhance or modify the properties of a great variety of perfumed end products. The perfuming microcapsules resulting from any embodiment of the process according to the invention can be incorporated in a perfuming composition such as a perfume, a Cologne or an after-shave lotion, or yet they can be added to functional products such as detergents or fabric softeners, soaps, bath or shower gels, deodorants, body lotions, shampoos and other hair- care products, household cleansers, cleaning and deodorising blocks for toilet tanks. The microcapsules of the invention are particularly useful for incorporation into consumer product bases such as detergent and deodorant and antiperspirant bases, as is shown in the examples presented further on.

Such consumer products are typically formed of an un-perfumed base which is typical of the nature of the product and generally compatible with fragrances. The nature and type of the constituents of the consumer product do not warrant a more detailed description here, which in any case would not be exhaustive, the skilled person being able to select them on the basis of its general knowledge and according to the nature and the desired effect of said product. To this base, the fragrance capsules of the invention can be added as such or in admixture with water-free co-ingredients, such as oils and water-free solvents, or other perfuming ingredients in non-encapsulated liquid or solid form. Alternatively, the consumer product base may already be added of a liquid perfuming composition having the same or different odor impact and tonality as the encapsulated perfume present in the invention's microcapsules.

Examples of suitable consumer product bases susceptible of being fragranced include solid or liquid detergent and fabric softener bases, as well as all the other articles common in perfumery, namely perfumes, colognes or after-shave lotions, perfumed soaps, shower or bath salts, mousses, oils or gels, hygiene products or hair care products such as shampoos, body-care products, deodorants or antiperspirants, air fresheners and also cosmetic preparations. As detergents there are intended applications such as detergent compositions or cleaning products for washing up or for cleaning various surfaces, e.g. intended for textile, dish or hard-surface treatment, whether they are

intended for domestic or industrial use. Other perfumed articles are fabric refreshers, ironing waters, papers, wipes or bleaches.

Consumer articles such as baby nappies can benefit specifically from the addition of the fragrance microcapsules of the invention which readily release a pleasant fragrance upon the baby's wetting of the nappy. Likewise, wipes intended to refresh the skin for example, by addition of water containing moisture agents, can advantageously contain such microcapsules. The latter are also advantageously using in air freshening "potpourri" type articles which can release a pleasant fragrance simply by spraying a small amount of water mist thereon and thus obtaining a fragrance bloom effect. The concentrations in which the microcapsules of the invention can be incorporated in such consumer products vary in a wide range of values, which are dependent on the nature of the product to be perfumed. Typical concentrations, to be taken strictly by way of example, are comprised in a range of values 0.05% up to 5 or 10% of the weight of perfumed article containing the microcapsules. Most typical concentrations vary between 0.1 and 10 or 15% by weight of microcapsules, more preferably from 0.5 to 5 weight %, and from 0.5 to 2 weight % of fragrance microcapsules, per total weight of finished consumer product into which they are included.

The invention will be now illustrated by way of, but not limited to, the following examples wherein temperatures are given in degrees centigrade and abbreviations have the meaning common in the art.

Brief Description of the Figures

Figures 1 to 5 show the weight change over time, reflecting the hygroscopicity, of a variety of fragrance microcapsules obtained as described in Examples 1 and 2 and subjected to a closed environment in which the relative humidity is varied as described in Example 3. Figure 6 shows the results of a 40 member panel blind evaluation of the perfuming effect of the invention's microcapsules described in Examples 1 and 2 when used in a powder detergent.

Figure 7 shows the results of a 40 member panel blind evaluation of the perfuming effect of the invention's microcapsules described in Examples 1 and 2 when used in spray antiperspirant aerosols.

Embodiments of the Invention

Examples 1 and 2

Perfumed spray-dried powders according to the invention

Several perfume emulsions, some according to the prior art or not performing optimally (comparative Examples I to VII), and others according to the invention (Examples 1 and 2) were prepared based on the different compositions given in Table 1 and Table 2 below. The compositions comprised a very volatile perfume composition (Lavender oil), and the ingredients indicated in the table.

The invention compositions were prepared by first dissolving the antioxidants, if used, in the perfume. The remaining ingredients were homogenised with an equivalent amount of water and then the perfume was emulsified in this dispersion by means of a Silverstone ^® type fast stirrer. All emulsions were spray dried in a Sodeva ^® type apparatus with an emulsion output of 0.5 kg/h, drying air: 320 m ³ /h at 350 ⁰ C and 0.45xl0 ⁵ Pa.

Several fine perfume powders were thus obtained, formed of microcapsules having a diameter comprised between 10 and 100 μm and having the liquid perfume content indicated in weight % relative to the total weight of powder. The amount of total encapsulated perfume (weight %) in the microcapsule powders obtained by spray-drying was determined by dissolving the microcapsules in water, followed by steam distillation of the volatile perfume.

The humidity resistance of the powders was measured in a powder detergent sample which was exposed for one month to 70% relative air humidity (RH) at a temperature of 37°C. Perfumed microcapsules were mixed into the powder detergent at a 1% weight concentration (relative to the total weight of detergent sample) and the detergent was stored in thin low-density polyethylene plastic film pouches which allowed air humidity

to transfer into the powder detergent and non-encapsulated perfume to diffuse out of the packaging.

The amount of perfume that leaked from the fragranced microcapsules contained in the detergent after one month storage in these conditions was determined by extraction of the detergent sample with acetonitrile. Acetonitrile dissolved the perfume no longer encapsulated (leaked perfume) without extracting the still encapsulated perfume. The amount of perfume thus carried in the acetonitrile was determined by GC-MS analysis. The amount of leaked perfume thus determined was compared to the total amount of perfume still in the detergent (as the pouches containing the detergent were permeable to the volatile perfume as well as to moisture, some of the perfume initially contained in the detergent before storage was also lost by evaporation, so a measure of the total amount of perfume still in the detergent after 1 month was necessary). The latter was determined by addition of water to a sample of the detergent after 1 month storage. In water, the microcapsules dissolved and released all the perfume they still contained. The water solution of the detergent thus obtained was then extracted with acetonitrile as described above to give the total content in perfume of the detergent sample.

The amount of perfume that was still encapsulated at the end of the one month storage period (weight %, last row of the Table) was determined as the difference between the total content in perfume of the detergent and the leaked perfume amount, measured as described above.

The explosive character of the powders was measured with a 20 1 sphere apparatus (see VDI Guideline 2263 part 1 : Dust Fires and Dust Explosions, Hazard Assessment - Protective Measures, Test Methods for the Determination of Safety Characteristics of Dusts, ISO standard procedure ISO 6184/1, Beuth, Berlin, May 1990). The results of the measurements described above are summarized in Table 1. They clearly show that the perfumed powders comprising Sokalan ^® CP 45 (invention Examples 1 and 2), a water soluble copolymer of acrylic acid and maleic acid, showed an increased resistance to humidity after one month storage under the conditions indicated, and could also present a reduced explosion risk, when compared to the powders whose matrix was based only on polysaccharides, or on mixtures of the latter with water-soluble polymers of a different nature.

The matrices comprising Sokalan ^® HP 165 (Example VI), a water-soluble polyvinylpyrrolidone, performed less well than those containing Sokalan ^® CP 45, both in

the amount of initially encapsulated perfume in the capsules and in its retention after storage.

From Table 1 it can also be seen that addition of non-water-soluble resins such as Synthomer ^® latex to the encapsulation matrix (comparative Example VII) also resulted in poor perfume encapsulation in the microcapsules, and poor retention after storage.

Table 1 : Composition of spray-dried fragrance powders

Lavender oil, origin: Firmenich SA, Geneva, Switzerland

2) dextrin dioctenylsuccinate; origin: National Starch, USA 3) polyvinylalcohol; origin: Omya, Switzerland 4) maleic acid, acrylic acid copolymer; 45% aqueous solution; solids: *7.50 parts by weight ; ** 10 parts by weight; origin: BASF 5) polyvinylpyrrolidone; 30% aqueous solution, solids:7.50 parts by weight; origin: BASF 6) styrene/butadiene latex; 40% solids; origin: Synthomer Ltd.

Table 2 : Composition of spray-dried fragrance powders

¹ ^ Lavender oil, origin: Firmenich SA, Geneva, Switzerland ² ^ dextrin dioctenylsuccinate; origin: National Starch, USA ³⁾ maleic acid, acrylic acid copolymer; 45% aqueous solution; solids: *7.50 parts by weight ; ** 10 parts by weight; origin: BASF

Example 3

Hvgroscopicity of the invention samples in comparison with the prior art ones

The hygroscopicity (the tendency to absorb water) of the microcapsules of comparative Examples I, III, IV, V and VII (prior art, Table 1), and of Examples 1 and 2 according to the invention, was determined in a Dynamic Vapor Sorption, apparatus commercialised by Surface Measurements Systems Ltd, 3 Warple Mews, Warple Way, London, W3 ORF, at increasing relative humidity values (40%, 50%, 60%, 70%, 80%), to determine the

"melting" point of the powders at 37°C, as well as the difference in weight of the powder which is placed on a balance in the humidity chamber. The "melting point", in the context of the present example, is the value of the relative humidity at which a powder has absorbed so much water that it loses its powdery aspect and starts to flow like a liquid,

that is, it "melts". The specific relative humidity value at which this happens can be determined by the weight-loss due to the release of the encapsulated volatile perfume. The microencapsulated perfume sample was put on a balance to be weighted, inside a chamber where the relative air humidity (represented in the figures by RH) was increased every two hours by 10%, starting from 40% RH. Initially, at the beginning of every two hour period, the exposed microencapsulated perfume sample increased in weight due to the moisture-uptake resulting from the increased humidity. Thereafter, if the microencapsulated perfume sample remained a powder and did not "melt", its weight remained constant over the period of two hours at constant humidity. If the microencapsulated perfume started "melting", the encapsulated perfume is no longer protected inside the matrix and started evaporating into the weighting chamber, resulting in the observed weight-loss over the constant humidity period.

In this manner, it was observed that the perfuming microcapsules of comparative Example I, where 15% monosodium phosphate was used in the emulsion to be spray- dried, "melted" at a relative humidity of 40% (Figure 1), whereas the microcapsules of comparative Example III, comprising 5% of potassium citrate, "melted" at a relative humidity of 60% RH (Figure 2). The invention's perfuming powders of Examples 1 and 2 remained stable until 90% RH (Figures 3 and 4). The perfuming microcapsules of comparative Examples VI and V, based on polyvinylalcohol, did not physically "melt" until 90% RH, but a strong perfume-loss was observed during the storage at 37°C (Figure 5).

These experiments showed that the use of acrylic acid, maleic acid film-forming resins Sokalan ^® CP 45 lead to less hygroscopic perfuming powders according to the invention.

Example 4

Perfuming effect of the microcapsules according to the invention in detergents

In a sensory panel blind triangle test with hand-wash powder detergents, it could be shown that spray-dried perfumed microcapsules prepared as taught in Examples 1 and 2, with 16.7% (equals 7.50% dry weight) Sokalan ^® CP 45 (from Example 1) dissolved easily in water and released the encapsulated perfume with a strong blooming effect,

similar to that observed with the comparative microcapsules obtained in Example III, whereas a retarded release however could be observed with spray-dried perfumed capsules prepared with 22.20% (equals 10.0% dry weight) of Sokalan ^® CP 45 (from Example 2), again compared to the same perfume microcapsules of comparative Example III, containing no resin Sokalan ^® CP 45.

Samples were prepared by instant dilution of 3 g of un-perfumed handwash powder detergent to which there had been added 0.50% weight of microencapsulated perfume of Examples II, 1 or 2 as the case may be, into 100 ml of tap water at 25°C, followed by stirring during 10 seconds.

Each of the 40 panelists of a sensory panel received a variety of samples for olfactive evaluation, in groups comprising 3 coded samples (blind evaluation), of which two were identical and one different, arranged in 6 different combinations, of the type ABB BAA BBA AAB BAB ABA. 50% Of the panelists received A as the odd sample and the others received B as the odd sample.

As is shown in Figure 6, the panelists could not clearly identify a difference between the samples of comparative Example III and Example 1 according to the invention, whereas the microcapsules of Example 2 according to the invention were perceived as being different from those of comparative Example III by a statistically significant number of panelists, who indicated that the microcapsules of Example 2 were generally perceived as conferring a weaker odor to the detergent solution, likely to indicate a slower dissolution of the capsules in water.

Example 5

Perfuming effect of the microcapsules according to the invention in antiperspirants

In a sensory panel triangle test in water-free antiperspirant sprays, it could be shown that the final spray-dried perfumed capsules prepared according to Example 2 showed a retarded release of the perfume, as compared to perfume microcapsules prepared as described in the prior art (comparative Example III).

An antiperspirant spray was prepared in a generally known manner using the ingredients summarized in Table 3, where the weight percentages indicated are relative to the total weight of antiperspirant composition.

Table 3

Preparation method: Mix DC 345 Fluid, IPM and Aerosil ^® 200 with Ultra-Turrax ^® until the mixture becomes thick and homogeneous. Add Aluminium chlorohydrate and continue stirring with Ultra- Turrax ^® apparatus. Reduce stirring speed using a wing stirrer and add perfumed microcapsules. The suspension is filled into aerosol cans using 25% of suspension and 75% of propellant (propane/butane) till a 2.5 bar pressure.

Evaluation samples were prepared by spraying 0.5 g of aerosol into a paper cup and leaving the cup for 2 hours. Then, 0.1% of water was sprayed into the cup in order to dissolve the perfumed microcapsules just before olfactive evaluation thereof. The samples thus prepared were blind evaluated by a 40 member panel using coded samples, in groups of 3 wherein two were identical and one different, arranged in 6 different combinations, of the type ABB BAA BBA AAB BAB ABA. 50% of the panelists received A as the odd sample and the others received B as the odd sample.

The panelists had to determine which was the odd sample by smelling the odor of the cups freshly sprayed with water.

This type of test is a standard method known as the Sensory Analysis Methodology Triangle Test BS-ISO-4120..2004, and the statistical analysis of the evaluation results is shown in Figure 7: a statistically significant number of panelists perceived a difference between the cups sprayed with the aerosol containing the microcapsules of Example 2, as compared to those sprayed with the aerosol comprising the comparative Example III microcapsules, the latter having been perceived as imparting a stronger odor to the cup, likely as a result of dissolving faster when water was sprayed. The cups sprayed with the aerosols of Examples III and invention Example 1 could not be differentiated by the panel in these blind evaluation tests.

In a second test, 0.1% of water mist was applied into the paper cups containing 0.5 g of the aerosols containing the microcapsules of comparative Example III, respectively invention Examples 1 and 2. The cups were allowed to stand for 2 hours and then another 0.1% of water mist was sprayed into the same paper cups, just before their evaluation.

Upon evaluation of the cups thus treated, using the same evaluation methods, statistic treatment of results of the panelists evaluation indicated similar sample differentiation behavior as mentioned before between the microcapsules prepared without Sokalan ^® CP 45 (Example III) and those with Sokalan ^® CP 45 (Examples 1 and 2), except that the cups sprayed with the aerosol containing the microcapsules of Example 2 were judged to have a stronger odor than the cups sprayed with the microcapsules of comparative Example III, or those sprayed with the aerosol comprising the invention's microcapsules of Example 1, thus clearly indicating that the microcapsules of the invention's Example 2 released their perfume more slowly when dissolved in water, providing controlled release of the fragrance over time.