WO2007137441A1

WO2007137441A1 - Microcapsules

Info

Publication number: WO2007137441A1
Application number: PCT/CH2007/000268
Authority: WO
Inventors: Christian Quellet; Sibilla Delorenzi; Jutta Hotz
Original assignee: Givaudan Sa
Priority date: 2006-05-30
Filing date: 2007-05-29
Publication date: 2007-12-06
Also published as: GB0610562D0

Abstract

A particulate composition comprising loosely-agglomerated microcapsules in the form of a fluffy powder that contain an ingredient for release into an aqueous environment, the microcapsules having, when dispersed in deionised water, an absolute zeta-potential of from 0.1 - 100 mV, preferably 1 to 60 mV and most preferably 5 to 40 mV. The composition is particularly effective for releasing fragrance in personal care and laundry and cleaning products.

Description

MICROCAPSULES

This invention relates to particulate compositions comprising water-dispersible, electrically-charged and highly fabric-substantive microcapsules containing micro- encapsulated ingredients, such as fragrances. The invention also relates to their intended use in consumer products such as detergents, especially laundry detergent and conditioners, including powders, tablets, softener sheets and liquids, and in particular to their ability to control the activation and diffusion of the ingredients in time in response to an external stimulus that is mechanical breakage and/or heat.

It is well known that ingredients such as fragrances, insecticides, malodour counteracting substances, fungicides and mildewicides, and the like may be encapsulated in a microcapsule comprising a solid shell or membrane, which protects them from their immediate environment and acts as means for their controlled release. A popular and convenient method of producing such encapsulated formulations consists of dispersing the ingredient in a liquid and creating a polymeric membrane on the surface of the droplets. Examples of suitable processes include the coacervation of gelatine with gum Arabic followed by cross-linking with glutaraldehyde. More generally, many polymers or mixtures of polymers capable of forming insoluble complexes under specific conditions can be used to form such interfacial membranes by so-called polymer phase separation process.

Alternatively, interfacial membranes can be produced by the interfacial polycondensation of various co-monomers and macromers. The polycondensation of melamine with formaldehyde to form so-called aminoplast microcapsules is the most popular among these processes. However, microcapsules having polyester, polyamides, etc. are also well known.

These established processes essentially convert emulsions consisting of a dispersed oil phase containing the ingredient to be encapsulated and a continuous water phase into a suspension of solid beads consisting of a core surrounded by a more or less permeable membrane, depending on the extent of cross-linking, the extent of polycondensation and/or

Bestatiguπgskppie the thickness of said membrane. Similarly, dispersions and suspensions of solid ingredients in water can be coated with such membranes.

Compositions formed in this manner produce excellent results in terms of high loading of ingredients and efficient release when mechanically broken by the effect of excessive shear stresses.

However, the art has paid very little attention to the essential step of incorporating such microcapsules into detergent powders and tablets. Similarly, the question of the stability of these microcapsules during storage in aggressive detergent bases at high relative humidity and high temperature has been widely ignored.

Incorporating any kind of microcapsules in granulated detergent leads often to problems. In particular, adding microcapsules of the abovementioned types in the form of slurries in water, i.e. in the form these microcapsules are obtained after coacervation or interfacial polymerization has been achieved, has the effect of adding appreciable amounts of water to the detergent base, which results in clogging and inhomogeneous distribution or segregation of the microcapsules within the mixture. Furthermore, increasing the humidity around the microcapsules generally accelerates chemical degradation of the microcapsule membrane by the action of free alkaline materials and enzymes.

Converting the microcapsules slurries into powders by conventional drying techniques, such as spray drying, generally results in the production of fine, free-flowing powders, such powders being the desired result because of the ease of handling they bring. Normally the product is aggregated particles, and these are generally reduced to powders by the addition of flowing agents, typically clays and silicates. However, such powders also contain high levels of dust, which constitute a potential safety hazard. Furthermore, free- flowing powders having mean particle sizes smaller than 100 micrometers are generally not suitable for incorporation into granulated detergent, due to size segregation. Such free- flowing powders have the tendency to accumulate at the bottom of packaging.

Capsules utilising aldehyde-based cross-linking agent have the additional disadvantage of high levels of free aldehydes being generated during storage, leading to unacceptable levels of, e.g., formaldehyde and glutaraldehyde in the product. This phenomenon is especially observed in conventional spray dried aminoplast microcapsules.

Another general problem to which little attention has been directed is that of improving the deposition and retention of such microcapsules on fabrics during laundering. It is generally believed that cationic species tend to deposit and remain on fabrics better than do non-ionic or anionic species.

Accordingly, there remains a need to provide microencapsulated compositions that permit of high loading of ingredients, and especially of fragrances, having a high fabrics substantivity, and which will release said ingredients on demand in a controlled manner, in response to a triggering stimulus, such as the action of mechanical shear stresses and/or heat, and which are not prone to segregation or chemical degradation when added to granulated bases. Furthermore, there remains a need to provide microcapsules that do not release unacceptable amounts of aldehyde moieties, and especially formaldehyde, during storage.

It has now been found that, by maintaining the agglomerated nature of the particles and by selecting the charge on the microcapsules under selected circumstances, it is possible to obtain compositions consisting of loosely agglomerated powders, essentially free of free- flowing fine particles, and which have a pronounced capability of admixing homogeneously with current granulated detergent bases, using standard mixing means such as rotary blenders and vortex mixing units. The compositions are chemically stable and have the capability of releasing electrically-charged and fabric-substantive microcapsules when dispersed in water and wash liquors.

There is therefore provided a particulate composition comprising microcapsules in the form of a fluffy or loosely agglomerated powder, which microcapsules contain an ingredient for release into an aqueous environment, the microcapsules having, when dispersed in deionised water, an absolute zeta-potential of from 0.1 - 100 mV, preferably 1 to 60 mV and most preferably 5 to 40 mV. There is additionally provided a process of releasing into an aqueous environment in a controlled manner an ingredient whose presence in that environment is desired, comprising the encapsulation of the ingredient in microcapsules, the incorporation of the microcapsules in the form of a fluffy or loosely agglomerated powder and the causing of the release of the ingredient into the environment at an appropriate time, characterised in that the microcapsules have, when dispersed in deionised water, an absolute zeta-potential of from 0.1 - 100 mV, preferably 1 to 60 mV and most preferably 5 to 40 mV.

The aqueous environment is particularly a wash or rinse liquor.

By "zeta-potential" (ζ) is meant the apparent electrostatic potential generated by any electrically charged objects in solution, as measured by specific measurement techniques. A detailed discussion of the theoretical basis and practical relevance of the zeta-potential can be found, e.g., in "Zeta Potential in Colloid Sciences" (Robert. J. Hunter; Academic Press, London 1981, 1988). The zeta-potential of an object is measured at some distance from the surface of the object and is generally not equal to and lower than the electrostatic potential at the surface itself. Nevertheless, its value provides a suitable measure of the capability of the object to establish electrostatic interactions with other objects present in the solution, such as surfactants, polyelectrolytes and surfaces. The zeta-potential is a relative measurement and its value depends on the way it is measured. In the present case, the zeta-potential of the microcapsules is measured by the so-called phase analysis light scattering method, using a ZetaPALS instrument (ex Brookhaven Instruments Corporation). The zeta-potential of a given object may also depend on the quantity of ions present in the solution. The values of the zeta-potential specified in the present application are measured either in deionised water, where only the counter-ions of the charged microcapsules are present, or in wash liquor, where other charged species are present. By "absolute zeta-potential" (|ζ|) is meant the absolute value of the zeta-potential without reference to its (positive or negative) sign. Hence, negatively-charged objects having a zeta-potential of -10 mV and positively charged species having a zeta-potential of +10 mV have the same absolute zeta-potential.

The compositions of this invention are fluffy or loosely aggregated powders that are slightly sticky and therefore not completely free flowing. This is typically the state in which spray drying or spin drying provides the particles. It is essential to this invention that this aggregated structure be attained. In the few cases in which a process naturally results in a free-flowing powder (no aggregates), the skilled person can easily achieve the necessary aggregates. As previously mentioned, they have the advantage of being essentially free of fine, free-flowing material. As a result, they admix better with detergent powders, suffer less from segregation (phase separation) of the powders, and result in less dust and considerably reduced (and sometimes no) settling of fine powder at the bottoms of drums and other containers.

In a specific embodiment of the invention, the aggregate compositions are produced in the form of loosely agglomerated powders having particle sizes ranging from 1 to 100, preferably from 20-80 and more preferably 40-60 micrometers, and characterized by a low level, i.e. less than 5 wt%, of free-flowing fine particles and high level of encapsulated ingredients, i.e. higher than 50 wt% by weight, preferably higher than 70 wt%.

The powder according to this embodiment also shows an excellent ability to mix homogeneously in consumer products available in granulated form, such as detergent powder, tablet bases and solid softeners. Given the ease of release previously mentioned, it is a particularly surprising feature of this invention that the microcapsules of this invention resist very well the pressures involved in tabletting, and there is no undue loss of encapsulated ingredient as a result of tablet formation. These powders can also be applied on consumer products available in the form of sheets or films, such as softener sheets, and dispersed in liquid products, such as personal wash compositions, fabric and hair care conditioners, and liquid detergents.

Microcapsules suitable for the sake of this invention are typically manufactured in the form of slurries, suspensions or dispersions in water according to any process known to the art such as coacervation, complex coacervation, interfacial polymerization (especially polycondensation), and more generally any kind of process known as polymer phase separation.

In a particular embodiment of the present invention, microcapsules are manufactured by polycondensation of methoxy methylolated melamine derivatives in the presence of a water-soluble polymer based on acrylamidosulfonate, as disclosed in, for example, WO 01/51197 and EP 0 978 312. The resulting slurry has a solid content ranging from 30 wt% to 40 wt% and a content of micro-encapsulated ingredient ranging from 25 wt% to 35 wt%. The slurry contains furthermore essentially anionic microcapsules showing a zeta potential ranging typically from -5 mV to -80 mV when dispersed in deionised water. One particular embodiment comprises microcapsules having zeta potentials ranging from -5 mV to -40 mV.

The microcapsules may be further cationized by depositing cationic surfactants or polyelectrolytes on to the surface of the microcapsules. Cationization of above microcapsules may be achieved, for example, according to the method described in FR 2 801 811.

The resulting slurry of microcapsules is spray-dried in a conventional spray drying tower, using a two-fluid nozzle, or spin-dried in a conventional spin dryer, to produce a fluffy or loosely aggregated powder having a loading of micro-encapsulated ingredient ranging from 70 wt% to 90 wt%, and having not more than 5 wt% free-flowing fine particles. It is believed that this fluffy structure is due to a limited but significant tackiness of the particles which is attributed to the presence of the adsorbed polyelectrolyte layer.

When admixed to conventional granulated detergent and submitted to the effect of a rotary blender, the powder according to the present invention surprisingly loses its fluffy structure and mixes intimately with the detergent powder to form a homogeneous mixture. Furthermore, submitting this mixture to mechanical vibration does not lead to any size segregation (e.g. separation between large detergent granules and small microcapsule- containing particles), which would normally be expected for mixtures of particles having essentially different sizes and densities.

In the case of liquid detergents and conditioners, the powder according to the present invention is slowly admixed to the product using a low shear mixer.

When added to deionised water, wash and rinse liquors, the composition of the present invention, per se or as admixture with abovementioned detergent products, is easily dispersed and releases electrically charged microcapsules. In a particular embodiment of the present invention, the microencapsulated ingredient is a fragrance material, a mixture of fragrance materials or a fragrance precursor. Further description will deal solely with this embodiment, but this is by way of example only and the skilled person will realise that other desirable materials may be incorporated.

Fragrance materials for use in compositions of the present invention may be selected from natural products such as essential oils, absolutes, resinoids, resins, concretes, and synthetic perfume components such as hydrocarbons, alcohols, aldehydes, ketones, ethers, acids, acetals, ketals and nitriles, including saturated and unsaturated compounds, aliphatic, carbocyclic and heterocyclic compounds, or precursors of any of the above. Other examples of odorant compositions which may be used are described in H 1468 (United States Statutory Invention Registration).

The amount of fragrance possible to be microencapsulated into the composition may be up to 50 wt%, in some cases even up to 90 wt%, e.g. 1 to 90 wt% based on dry material, with a micro-encapsulation yield close or superior to 80 wt%, even for the very volatile components having a Loss Factor of greater than 10² Pa ppm. The term "Loss Factor" refers to a parameter that is related to the losses of fragrance material during drying and is defined as the product of the pure component vapour pressure (Pa) and the water solubility (ppm) at room temperature. Vapour pressures and water solubility data for commercially available fragrance components are well known and so the Loss Factor for a given fragrance component may be easily calculated.

Alternatively, vapour pressure and water solubility measurements may be easily taken using techniques well known in the art. Vapour pressure of fragrance components may be measured using any of the known quantitative headspace analysis techniques, see for example Mueller and Lamparsky in Perfumes: Art, Science and Technology, Chapter 6 "The Measurement of Odors" at pages 176 - 179 (Elsevier 1991). The water solubility of fragrances may be measured according to techniques known in the art for the measurement of sparingly water-soluble materials. A preferred technique involves the formation of a saturated solution of a fragrance component in water. A tube with a dialysed membrane is placed in the solution such that after equilibration an idealised solution is formed within the tube. The tube may be removed and the water solution therein extracted with a suitable organic solvent to remove the fragrance component. Finally the extracted fragrance component may be concentrated and measured, for example using gas chromatography. Other methods of measuring fragrances are disclosed in Gygax et al, Chimia 55 (2001) 401-405.

In a particular embodiment, the fragrance is admixed with a dilution medium, such as hydrocarbon waxes, silicone waxes, alkyl silicone waxes, beeswax, fatty acid esters, and the like, prior to encapsulation, whereby the level of fragrance in the microcapsules is maintained below 50 wt%.

In a further particular embodiment, the composition according to the invention is characterized by its ability to deliver microcapsules having an absolute zeta-potential higher than 0.1 mV and lower than 100 mV, when dispersed in deionised water, whereas the sign of the electrical charge, as measured in deionised water, is selected such that it is opposite to the charge of the main ionic surfactants present in the consumer product in which the composition is to be incorporated. Thus, for detergents, this electrical charge is usually positive (as detergents are generally anionic), whereas, for conditioners (generally cationic), this electrical charge is generally negative. Preferably, microcapsules according to this embodiment, intended for use in detergents, have a positive zeta-potential comprised between +0.1 mV and +40 mV, while microcapsules intended for use in liquid conditioners have a negative zeta-potential between -5 mV and -40 mV.

The microcapsules according to this preferred embodiment are further characterized by their ability to undergo an electrical charge inversion when dispersed in wash and rinse liquors, where they acquire an electrical charge of the same sign as that of the main ionic surfactant present in the liquor. Hence, in detergent liquors containing essentially anionic and non-ionic surfactants, the microcapsules acquire a negative zeta-potential, and, in conditioning liquors containing essentially cationic actives, the microcapsules acquire a positive zeta-potential.

In another particular embodiment, at least one hydrocolloid may be added to the microcapsule slurry, as such or in the form of an aqueous solution. Typical hydrocolloids include starch, modified starch such as dextrin-modified with octenyl succinate anhydride; cellulose, cellulose derivatives such as carboxymethylcellulose and hydroxypropyl methylcellulose, polyvinylpyrrolidone and polyvinylpyrrolidone copolymers , polyvinylalcohols, aceto-acetyled polyvinyl alcohols; polyalkyleneoxides, such as poly(ethyleneoxide-b-propyleneoxide) diblock and triblock copolymers; silicones bearing polyether moieties, polymaleic anhydride copolymers, and the like. Particular polyvinyl alcohols have a viscosity measured at room temperature and as a 30 wt% solution in water at a shear rate of 100s^"1 lower than about 10,000 mPas, more preferably below about 5,000 mPas. In order to ensure that the polymer has viscosity in the desired range, one preferably employs a polyvinyl alcohol having a molecular weight M_w of above 10,000 Daltons but lower than about 40,000 Daltons.

On drying, the hydrocolloids form a water-soluble or water-dispersible coating on the particles, conferring added protection to the dry capsules. The particulate composition according to this latter embodiment comprises typically 30 - 98 wt%, preferably 30 - 70 wt% of water insoluble microcapsules, and 10 - 2 wt%, preferably 70 - 30 wt% of a water- soluble component comprising dry hydrocolloid.

In the particular case that the hydrocolloid is an aceto-acetylated polyvinyl alcohol, it has been surprisingly found that there is a drastic reduction in the amount of formaldehyde released over time from the microcapsules after the slurry has been spray-dried. Example of suitable aceto-acetylated polyvinyl alcohols include those available under the trade name "Gohsefimer" Z 100 or "Gohsefimer" Z 200 (ex Nippon Gohsei).

In a further particular embodiment, the hydrocolloid may itself contain fragrance. This fragrance may be the same as, or different form, that in the capsule. All of the abovementioned fragrances and hydrocolloids are useful for this embodiment. This is achieved by performing the step of (1) emulsifying the fragrance in aqueous hydrocolloid solution, optionally additionally comprising fillers such as maltodextrins and sugars or sugar alcohols, to form a second slurry (2) mixing the second slurry with the capsule slurry and (3) drying this mixture. The result is the formation of a loosely agglomerated composite powder comprising (a) 10 to 90 wt%, preferably 30 to 70 wt% of spray dried microcapsules, comprising typically 70 to 90 wt% of first fragrance, coexisting with (b) 90 to 10 wt%, preferably 70 wt% to 30 wt% of spray dried water-soluble or water-dispersible encapsulating material, comprising typically 10 to 50 wt%, preferably 30 to 50%, of second fragrance.

The advantage of this fragrance encapsulation embodiment is particularly obvious in the case it is desired that both first and second fragrances are released according to different release mechanisms and at different moments of the application. Hence, it will be obvious for the person skilled in the art, that, when used in a washing or conditioning application, the second fragrance will be released essentially by the dissolution or dispersion of the water-soluble or water-dispersible encapsulating material under the action of water or excessive humidity, while the first fragrance will be released essentially by the action of mechanical stresses, as stressed above. When the first and second fragrances are different, there is provided a programmed perception of different smell or sensory experience at different moments of the application. Hence, for example, the second fragrance may be released at an early stage of the washing or conditioning process, when the composite powder is contacted with water, while the first fragrance may be released at a later stage, e.g. by agitating the fabrics during wash or folding, unfolding, or wearing clothes treated with laundry products containing the composite powder.

The specific composition for use in powder detergents and tablet detergent bases constitutes another particular embodiment of the present invention and is discussed in detail first. The composition according to this embodiment is obtained by following the steps of:

preparing an initial slurry, suspension or dispersion of microcapsules in water bearing a negative electrical charge; converting said slurry, suspension or dispersion of microcapsules into a slurry, suspension or dispersion of electrically positively charged microcapsules by adsorbing at least one cationic polyelectrolyte onto the surface of these microcapsules; - optionally adding at least one hydrocolloid to the slurry, suspension or dispersion; and spray drying or spin drying said slurry, suspension or dispersion in a conventional spray drying unit or spin dryer unit. This is now described in more detail. These details are exemplary and are not to be regarded as being in any way limiting.

1. Slurries, suspensions or dispersions of microcapsules in water may be made according to any process known to the art, such as coacervation, complex coacervation, interfacial polymerization (especially polycondensation), and more generally any kind of process known as polymer phase separation. The microcapsules obtained have preferably a negative zeta potential ranging preferably from -0.1 to -100 mV, more preferably from -1 mV to -60 mV, most preferably from -5 to -40 mV after dilution in deionised water. Preferably, said microcapsules are manufactured by polycondensation of methoxylated melamine derivative in the presence of a water-soluble polymer based on acrylamidosulfonate, as disclosed in, for example, WO 01/51197 and EP 0 978 312. The resulting slurry has a solid content ranging from 30 wt% to 40 wt% and a content of microencapsulated ingredient ranging from 25 wt% to 35 wt%.

2. The suspensions of microcapsules are converted into suspensions of positively-charged microcapsules by adsorbing cationic polyelectrolytes onto the surface of these microcapsules. After conversion, the microcapsules have a positive zeta potential ranging particularly from +0.1 mV to +40 mV, more particularly from +5 mV to +40 mV. Particularly, cationization of the abovementioned microcapsules may be achieved, for example, according to the method described in FR 2 801 811.

3. Hydrocolloids may optionally be added to said suspensions.

4. The suspensions are spray-dried in a conventional spray drying units operating at 160 °C inlet temperature and 80 ⁰C outlet temperature, or spin drying said suspensions in conventional spin dryer units operating at a typical rotating speed of fromlOOO to 3000 rpm, to produce a loosely aggregated powder having a loading of micro-encapsulated ingredient ranging from 70 wt% to 90 wt%.

Powders obtained by performing steps 1 to 4 present a loosely agglomerated and/or fluffy structure and do not contain more than 5 wt% free-flowing fine particles. There is therefore additionally provided a composition preparable by this process, having the form of a fluffy or loosely agglomerated powder comprising more than 80 wt%, preferably more than 95 wt% microcapsules and less than 5 wt% free-flowing fine particles.

If conditioners are concerned, the procedure according to the present embodiment is essentially the same as that described in the embodiment specific to detergents but, in this case, the second step in the manufacturing process hereinabove described, i.e. charge inversion, is omitted.

The amount of fragrance composition employed in perfumed products or articles according to the present invention may vary according to the particular application in which it is employed and on the fragrance loading in the fragrance composition. For laundry care applications, one may employ fragrance composition in amounts form 0.01 to 3% by weight of fragrance material based on the total weight of the detergent.

The compositions according to the invention are especially useful in personal care and household, washing and cleaning products, such as soaps, shampoos, skin care creams, laundry detergents, fabric conditioners, dishwashing liquids, furniture polishes and the like. The invention therefore provides a personal care product, a household product, a washing product or a cleaning product, comprising a composition that comprises microcapsules as hereinabove defined.

There now follows a series of examples, plus two drawings, that serve to illustrate embodiments of the present invention. The drawings are graphical representations of results obtained, and they are explained in the relevant examples. It will be understood that these examples and drawings are illustrative, and the invention is not to be considered as being restricted thereto.

Example 1 : Preparation of anionic microcapsules

Aqueous suspensions of negatively charged microcapsules in water are manufactured by polycondensation of methoxylated melamine pre-polymer in the presence of a water- soluble polymer based on acrylamidosulfonate and a perfume composition as hydrophobic material, as disclosed in WO 01/51197. The resulting slurries have a solid content of 35±5 wt% and a perfume content of 27±3 wt%. The microcapsules have an average diameter of 60±10 micrometers and a negative potential equal to - 56±5 mV when dispersed in deionised water.

Example 2: Preparation of cationic microcapsules

Electrical charge inversion is achieved according to the method of FR 2 801 811, by adsorption of a positively-charged polyelectrolyte (Gafquat™ HS 100, ex ISP) on the microcapsules of Example 1, which thereby are converted into positively charged microcapsules having a an almost unchanged average diameter equal to 60±10 micrometer, and a zeta potential equal to +19±2 mV, as measured after dilution in deionised water.

Example 3: Preparation of loosely agglomerated powder containing microcapsules by spray drying.

3O g Gohsefimer™ Z 100 (ex Gohsenol Corporation) is dissolved into 1600 ml aqueous suspension containing 270 g of microcapsules manufactured according to the procedures mentioned in Example 1 and Example 2, under gentle stirring and the suspension is pumped into a two-fluid nozzle at a rate of 28.6 g/min. Spray drying is conducted in a NIRO MOBILE MINOR spray drying tower at an inlet temperature of 160 ⁰C and outlet temperature of 80 ⁰C.

The resultant powder is loosely agglomerated and substantially free of free-flowing particles, and has a particle size of 75 ± 5 micrometers, a total oil content of 85 ± 5 wt%, as measured by pulsed NMR method using an Oxford MQA6005 (Oxford Instruments IAG, UK), reflecting that close to 100 wt% of the perfume is present in liquid form in the microcapsules.

Example 4: Preparation of loosely agglomerated powder containing microcapsules by spin drying

10 kg of microcapsules slurry, prepared according to Examples 1 and 2, is placed in a stainless steel horizontal spin dryer having a gasket diameter equal to 40 cm and variable rotation speed of up to 3000 rpm. The slurry is spin-dried, firstly at a rotation speed of 1000 rpm and then at 2500 rpm. The resulting cake is washed with 3 kg water and the spin drying procedure is repeated.

The cake is then transferred to a conventional horizontal dryer in order to remove the remaining water, yielding a loosely agglomerated powder; essentially free of free-flowing particles and containing 85% encapsulated perfume and less than 4% water.

Example 5: Preparation of composite powder showing dual release behaviour, by spray drying

In a first step, a portion of a perfume composition (apple accord) (i.e. 50 wt% of the overall perfume to be converted in powder form) is encapsulated and cationised according to Examples 1 and 2. The microcapsule slurry has a solid content of 35 wt% and a perfume content of 28 wt%.

In a second step, the remaining 50 wt% of the same perfume composition is emulsified in an aqueous solution of Capsul™ E (ex National Starch) and Maltodextrin IT 6 (ex Roquette Freres) by vigorous stirring until the perfume droplets reach an average diameter of less than 2 micrometers. The composition of this slurry is 20 wt% perfume, 7 wt% Capsul E, 33 wt% maltodextrin and 40% water.

50 wt% of first slurry is admixed with 50 wt% of second slurry and the mixture is spray dried according to Example 3 to form a composite powder consisting of (i) dry, essentially water-insoluble microcapsules and (ii) dry, water-soluble powder, both containing part of the initial perfume. The powder is loosely agglomerated and substantially free of free- flowing particles.

Example 6: Application tests related to Examples 1 to 3 in powder detergent

A series of essentially non-substantive fragrance accords is microencapsulated according to Example 1. The microcapsules are cationized according to Example 2, and dried according to Example 3. The composition is mixed in standard, non-perfumed detergent powder base at 0.3 wt% and 1% perfume level, and 100% perfume encapsulated. Machine wash conditions: 220 g terry towels, 32 g wash powder, ca. 101. water, wash temperature = 40 ⁰C.

5 Olfactory evaluation is performed by 6 trained panelists. Assessment is made 2 hours after rinse (wet towels), and after 4 days and 19 days (line-dried towel, before and after gentle rubbing). Intensity scale: 0 = not perceivable, 1 = very weak, 2 = weak, 3 = medium, 4 = strong, 5 = very strong.

10 Table 1 : Description of samples:

Towel Spray dried powder # Microcapsules # Perfume

(loading)

15 47, B 1 (86 wt%) 1 A (apple accord)

X, Y 2 (90 wt%) 2 B (neroli accord)

3, 28 free perfume A (apple accord)

A, 13 free perfume B (neroli accord)

2, 11 3 (85 wt%) 3 C (flowery accord)

20 57, 49 4 (88 wt%) 4 D (lavender accord)

16, 1 free perfume C (flowery accord)

C, 8 free perfume D (lavender accord)

25 Evaluation on wet towels (2h after rinse. 1% perfume level):

The results are shown in Figure 1.

The impact of spray dried samples 1, 2 and 3 is clearly stronger than that of the 30 corresponding free fragrances at all stages of the assessment, i.e. even on wet towels and without rubbing. As 100% of the perfume was encapsulated, this suggests that perfume diffusion through the wall occurs in all cases in humid environment. The large difference in impact on wet between the microcapsules and the free accords is also the signature of a very significant enhancement of perfume deposition obtained with these microcapsules.

Evaluation on dry towels (after 19 days, 0.3% perfume level) before and after rubbing the fabrics:

The results are shown in Figure 2.

Mechanically disrupting the capsules by rubbing clearly boosts the perfume impact, although this effect is less obvious for samples 1 and 2 than for samples 3 and 4. On the other hand, the intensity of sample 3 and 4 is very weak before rubbing, which suggests that corresponding perfume oils (C and D) are better retained in the microcapsules over time than the perfume oils A and B.

After 19 days, all capsules are easily reactivated by rubbing. This is a remarkable result. Again, perfume A was clearly perceivable, even without rubbing.

Example 7: Application test related to Examples 5 in powder detergent

A first microcapsule slurry containing 32 wt% of first perfume composition Pl (floral note) is prepared according to Example 1 and cationized according to Example 2. The microcapsules have a diameter equal to 60 micrometers and a zeta-potential of + 22 mV in deionised water.

Four powders are prepared by spray drying the following systems:

1. First slurry diluted with 700 g of an aqueous solution containing 60 g of mannitol 60 (8.6%) (ex Roquette Freres) and 240 g (34 wt%) (of Capsul (ex National Starch). 2. Second slurry prepared by dispersing 27 wt% of a second perfume composition P2 (green apple note) in an aqueous phase containing 22 wt% of Capsul (ex National Starch), 4.4 wt% mannitol 60 (ex Roquette Freres) and 46.6 wt% water. 3. Mixture comprising 375 g (31.3 wt%) of first slurry and 825 g (68.7 wt%) of third slurry containing 135 g (16.4 wt%) first perfume Pl (floral note), 252 g (30.5 wt%) of Capsul (ex National Starch), 63 g (7.6 wt%) of mannitol 60 (ex Roquette Freres) and 375 g (45.5 wt%) water. 4. Mixture comprising 375 g (31.3 wt%) of first slurry and 825 g (68.7 wt%) of third slurry containing 135 g (16.4 wt%) second perfume P2 (green apple note), 252 g (30.5 wt%) of Capsul (ex National Starch), 63 g (7.6 wt%) of mannitol 60 (ex Roquette Freres) and 375 g (45.5 wt%) water.

Evaluation results in the presence of a free perfume different from the encapsulated perfume(s)

The four powder samples are incorporated, at a perfume level of 0.05 wt%, in a conventional hand wash detergent powder perfumed at 0.25 wt% with a typical detergent perfume (third perfume P3, floral, woody).

Hand wash tests are performed at 25 ⁰C usingl 1O g terry towels in 1 1 water containing 5 g detergent powder. The towels are squeezed and rinsed with 1 1 water, squeezed again, spin- dried and line-dried. Olfactive evaluation is performed at various stage of the process (neat product, when the detergent is added to water, during squeezing the towels, on wet towels, after 24 hours line drying, when rubbing the dry towels) and rated in terms of intensity (Intensity scale: 0 = not perceivable, 1 = very weak, 2 = weak, 3 = medium, 4 = strong, 5 = very strong) and quality (see table 2). In addition, the panel judges the hedonic impression of the fragranced powders and gives an approval rating (the greater the number of pluses, the higher the rating, from + (acceptable) to ++++ (outstanding)).

Table 2: Olf active evaluation

The microcapsules used alone or with a conventional spray dried fragranced powder, offer clearly perceivable hedonic advantages, such as a programmed release of different olfactive notes in the same laundering application.

Evaluation results in presence of a free perfume identical to the encapsulated one

A series of detergent formulations are prepared as follows:

A. 0.3% of perfume Pl (fruity note) is incorporated in the form of free oil in the detergent powder.

B. Powder 1 is incorporated at a level of 0.05 wt% encapsulated perfume Pl in the detergent powder containing 0.25 wt% free perfume Pl.

C. Powder 3 is incorporated at a level of 0.05% encapsulated perfume Pl in the detergent powder containing 0.35 wt% free perfume Pl .

Both hand wash and olfactive evaluation are preformed as above. The results are shown in

Table 3. Olfactive evaluations

The microcapsules used alone or with a conventional spray dried fragranced powder, offer clearly perceivable hedonic advantages, even with same perfume inside or outside of the delivery system, such as an enhancement of both impact and long lastingness of the perfume.

Example 8 Application test related to Examples 1 to 4 in liquid fabric softener

Anionic microcapsules containing a green apple accord and having an average diameter of 50 micrometers, and a zeta-potential in deionised water equal to -22 mV are prepared according to Example 1, and dried according to Example 3 or Example 4.

The microcapsules are incorporated under gentle mixing at 0.3 wt% perfume level in standard, liquid fabric softener base containing 0.7 wt% non-encapsulated perfume (e.g. "free perfume"), the non-encapsulated perfume being different in composition and olfactive character from the encapsulated accords. Machine rinse conditions: 220 g towels, 23 g fabric softener, ca. 10 1 water.

Olfactory evaluation is performed by 6 trained panelists. Assessment is made after 24 hours and after 5 days (line-dried towel, before and after gentle rubbing). Intensity scale: 0 = not perceivable, 1 = very weak, 2 = weak, 3 = medium, 4 = strong, 5 = very strong.

(*) Rubbing the fabrics after 24 hours and 5 days releases an olfactive note which is clearly more intense and different than that provided by the ingredient of the free perfume remaining on the towel.

Claims

Claims:

1. A particulate composition comprising microcapsules in the form of a fluffy or loosely agglomerated powder, which microcapsules contain an ingredient for release into an aqueous environment, the microcapsules having, when dispersed in deionised water, an absolute zeta-potential of from 0.1 - 100 mV, preferably 1 to 60 mV and most preferably 5 to 40 mV.

2. A composition according to claim 1, in which the composition has a particle size range of from 1 to 100, preferably from 20-80 and more preferably 40-60 micrometers, and less than 5wt%, of free-flowing fine particles and more than 50 wt%, preferably more than 70 wt%, of encapsulated ingredients.

3. A composition according to claim 1, in which the microcapsules acquire, when dispersed in a wash or rinse liquor, an electrical charge of the same sign as that of a main ionic surfactant present in the liquor.

4. A composition according to claim 1, in which the microcapsules are manufactured by polycondensation of methoxylated melamine derivative in the presence of a water-soluble polymer based on acrylamidosulfonate.

5. A composition according to claim 1 , for use in a powder or tablet detergent base, preparable by a process comprising the following steps:

- preparing an initial slurry, suspension or dispersion of microcapsules in water bearing a negative electrical charge; converting said slurry, suspension or dispersion of microcapsules into a slurry, suspension or dispersion of electrically positively charged microcapsules by adsorbing at least one cationic polyelectrolyte onto the surface of these microcapsules ; optionally adding at least one hydrocoUoid to the slurry, suspension or dispersion; and spray drying or spin drying said slurry, suspension or dispersion in a conventional spray drying unit or spin dryer unit.

6. A composition according to claim 5, in which the initial slurry, suspension or dispersion has a negative zeta-potential when dispersed in deionised water.

7. A composition according to claim 5, in which the converted slurry, suspension or dispersion has a positive zeta-potential of from +0.1 mV to +40 mV after dilution in deionised water.

8. A composition according to claim 1, for use in liquid or solid conditioner products, including softener sheets, preparable by a process comprising the following steps:

preparing an initial slurry, suspension or dispersion of microcapsules in water bearing a negative electrical charge; - optionally adding at least one hydrocolloid to the slurry, suspension or dispersion; and spray drying or spin drying said slurry, suspension or dispersion in a conventional spray drying unit or spin dryer unit.

9. A composition according to claim 1, having the form of a fluffy or loosely agglomerated powder comprising more than 80 wt%, preferably more than 95 wt% microcapsules and less than 5 wt% free-flowing fine particles.

10. A composition according to claim 8, in which the converted slurry, suspension or dispersion has a negative zeta-potential of from -0.1 mV to -80 mV, preferably -5 mV to -4OmV after dilution in deionised water.

11. A process of releasing into an aqueous environment in a controlled manner an ingredient whose presence in that environment is desired, comprising the encapsulation of the ingredient in microcapsules, the incorporation of the microcapsules in the form of a fluffy or loosely agglomerated powder and the causing of the release of the ingredient into the environment at an appropriate time, characterised in that the microcapsules have, when dispersed in deionised water, an absolute zeta-potential of from 0.1 - 100 mV, preferably 1 to 60 mV and most preferably 5 to 40 mV.

12. A personal care product, a household product, a washing product, a cleaning product, or a conditioning product comprising a composition according to claim 1.

13. A dry particulate composition according to claim 1, comprising 10 - 90 wt%, preferably 30 - 70 wt% of water insoluble microcapsules, and 90 - 10 wt%, preferably 70 - 30 wt% of a water-soluble component comprising hydrocolloid.

14. A particulate composition according to claim 13, in which the hydrocolloid comprises an encapsulated ingredient.

15. A particulate composition according to claim 14, where the encapsulated ingredient is a fragrance, a fragrance ingredient or a precursor thereof.

16. A particulate composition according to claim 15, where the water-insoluble microcapsules and the water-soluble component comprise different fragrances, the former being released by mechanical action, and the latter being released in contact with humidity or water.

17. A personal care product, a household product, a washing product, a cleaning product, or a conditioning product comprising a composition according to claim 13.