GB2473870A - Dispersion of microbeads comprising droplets of active within a hybrid matrix - Google Patents

Abstract

A dispersion of active-containing microbeads within a non-aqueous continuous phase, the microbeads comprising a plurality of droplets of active within a hybrid matrix. The matrix comprises both a hydrophilic organic material selected from poly(vinyl alcohol), poly(carbohydrates) and poly(alkylene glycols), and an inorganic oxide that forms continuous network through the organic material. Preferably, the organic material is a polyvinyl alcohol (PVOH) having a degree of hydrolysis from 50-99%; cellulose; hydrolysed starch; organic gums; polyethylene glycol. Preferred inorganic materials include silicon alkoxides, optionally partially or totally hydrolysed; inorganic precursors M(OR"')0-4X0-4, wherein M is a metal or metalloid, R"' is a lactate, alkyl or aryl residue and X is an halogen. The continuous phase may contain the same or a different active than the microbeads. The preparation of a microbead active delivery system comprising the dispersion of the invention. The examples relate to dispersions with hybrid matrices made from PVOH Mowiol (RTM) and tetraethoxy silane (TEOS) precursors. Exemplified applications include a shampoo composition comprising perfume microbeads in a continuous phase of the same fragrance; a toothpaste including flavour oil microbeads dispersed in a continuous phase with a different flavour.

Description

PRODUCT

This disclosure relates to active-containing microbeads, to a method of preparing a dispersion of such microbeads, and to a dispersion of microbeads prepared thereby.

By "microbead" is meant a microparticle comprising a multiplicity of liquid droplets within a matrix. In this, it is distinguished from the classical microcapsule, which comprises a single droplet, surrounded by an encapsulating wall. By "active" is meant any liquid ingredient whose gradual release into a given environment is desired. Such actives include fragrances, insecticides, disinfectants, medicaments, malodour counteractants, fungicides, mildewicides, and the like. In the following description, the use of such microbeads in conjunction with fragrances will be exclusively discussed, as this is one of the most important uses. However, the factors involved in fragrance apply also to other actives and analogous situations, with only minor changes that would be clear to the skilled person, and the description should be read as including them.

Such microbeads are desirable, because they offer a variety of release mechanisms, which are not achievable with classical microcapsules. For example, they can be tailored in such a *. : way that fragrance therein is released by slow erosion of the matrix during the application S...

of the product containing the microbeads or the subsequent abrasion of the applied microbeads. "Application" here includes such activities as washing, rinsing or conditioning substrates such as fabrics, skin or hair, and abrasion includes such activities as combing the hair or drying oneself with a towel washed or conditioned with a product containing such microbeads. This results in the fragrance droplets being released continuously into the 25 wash or rinse liquor, providing long-lasting olfactive benefits both during and after application. These include better deposition of the fragrance on the substrate and deposition of the microbeads themselves on the substrate and their breakage over time under the action of mechanical forces, such as those involved during wearing or using fabrics or combing hair. This post-deposition breakage is particularly desirable.

These microbeads are generally made by emulsifying a fragrance into a matrix precursor, emulsifying this fragrance-precursor emulsion into a continuous phase, and causing a matrix to form. These have been hard to make, because it is hard to maintain stability of the initial fragrance-matrix precursor -the individual droplets tend to agglomerate into a single large droplet, and ultimately the components tend to separate completely into two layers.

A further desirable product is a dispersion of such microbeads in a continuous phase of active, particularly fragrance. This can be used to give products two fragrance emissions, an initial fragrance from the continuous fragrance phase, followed by a long-lasting fragrance from the encapsulated fragrance. It is of course possible to make such a product by making fragrance-containing microbeads, isolating them from the continuous phase in which they were made, for example, by drying, and then re-dispersing them in the desired fragrance continuous phase. This is an involved (and therefore undesirably expensive) process. This problem could be overcome by making the microcapsules in a fragrance as continuous medium, but this is difficult to achieve, largely because a fragrance is a complex mixture of ingredients, rather than the usual single-substance solvent continuous phases in which such operations are conventionally performed. Such a process can have adverse effects on the continuous phase, diminishing its olfactory performance.

It has now been found that these problems may be substantially or even completely * overcome by the use of a particular technique. There is therefore provided a dispersion in a * S.. * S

non-aqueous continuous phase of active-containing microbeads, the microbeads comprising a plurality of droplets of active within a matrix, the matrix being a hybrid *5S* material comprising both organic and inorganic materials, the organic material being a * hydrophilic material selected from poly(vinyl alcohol), poly(carbohydrates) and poly(alkylene glycols), and the inorganic material being an oxide that forms a continuous 25 network through the organic material.

The hydrophilic organic material of the matrix may be selected from one or more of the abovementioned materials. Typical (and non-limiting) examples of the various materials are: -Poly(vinyl alcohol) having hydrolysis grades ranging from 50 to 99%, and including cationic-modified and aceto-acetylated polyvinyl alcohols; -Poly(carbohydrates), including cellulose (including cationic cellulose), hydrolyzed starch, and organic gums, such as gum Arabic and locust bean gum, -Poly(alkylene glycols), particularly polyethylene glycol.

In a particular example, the hydrophilic organic material is a polyvinyl alcohol having a degree of hydrolysis from 50 to 80%, optionally admixed with a polyvinyl alcohol having a degree of hydrolysis from 80 to 99%. More particularly, the hydrophilic organic material is at least one polyvinyl alcohol having a degree of hydrolysis of 88%. Typical suitable commercial materials include MowiolTM 4/88 and MowiolTM 15/79 (ex Kuraray).

The inorganic oxides may be any such oxides capable of forming a continuous network through the matrix (as opposed to isolated occlusions). Such a network must necessarily be formed in situ from a precursor, so the oxides suitable for use will be determined by the existence of suitable precursors. The process itself is well known, and is essentially identical to the so-called "sol-gel" process process used to make ceramics (see for example "Sol-Gel Science", C. Jeffrey Brinker, Academic Press 1990). The matrix forms by polycondensation of inorganic precursors in the presence of the hydrophilic polymers in S...

: the interstitial water phase under acidic conditions. S... * .

Any material that can do this (and the ability is easily determined by routine S...

experimentation) is suitable as a precursor. Typical non-limiting examples include: -Silicon alkoxides of the general formula Si(OR)4, where R is a alkyl radical, and * ** :.. partially or totally hydrolyzed forms of these silica alkoxides, 25 -Inorganic precursors having the formula M(R')n(R")m, where M is a metal, such as aluminium, titanium, vanadium, or zirconium or a metalloid, such as silica or germanium, R' is an alkoxy moiety of formula O-R", where R" is selected from lactate, alkyl or aryl residues; R" is a halogen; and n and m are integers having values 0, 1, 2, 3 or 4.

The continuous phase may comprise a non-aqueous solvent. Thus, when the microbeads have been prepared, the solvent may be removed to give dry beads, which may be reused in a desired application. However, in a particular embodiment, the microbeads are used in the dispersion in which they are prepared. In a particular embodiment, the continuous phase consists of or comprises an active (hereinafter "active continuous phase"). An example is fragrance-containing microbeads in a continuous phase of fragrance, which may be the same as, or different from, the fragrance within the microbeads.

A feature of this delivery system is that the active-containing microbeads may be prepared in an active continuous phase. There is additionally provided a method of preparing a microbead active delivery system as hereinabove described, comprising the steps of (a) preparing a mixture of the active to be encapsulated and a matrix precursor; (b) dispersing this mixture in an active continuous phase; and (c) causing the matrix precursor to form an encapsulating matrix; characterised in that the matrix precursor comprises both inorganic and organic components, the organic component being an aqueous solution of a material selected from poly(vinyl alcohol), poly(carbohydrates) and poly(alkylene glycols), and the inorganic material being an aqueous material that forms a continuous oxide network through the organic material, the water content of the matrix being 25% to 95% by weight of water.

The presence of 25-95% water during the preparation is essential. Water is necessarily . : present as the solvent of the organic material, but the proportion is important. Water * **.

*** * 20 contents outside this range cause instability and result in failure to form microbeads. In a particular embodiment, the water content is from 50-95 %. I... *

*5S**S By way of example, there follows the description of a particular embodiment, a delivery system prepared from tetra-ethoxy silane (TEOS) as inorganic precursor and polyvinyl * 25 alcohol as hydrophilic polymer, using a procedure generally known for the preparation of multiple emulsions and involving the following steps: 1. A first active is emulsified in water in the presence of pre-hydrolysed silica precursor and polyvinyl alcohol, under high shear mixing conditions, to form a first oil-in-water emulsion of droplet size between 0.5 and 20tm. The choice of agitating means and agitation rate to achieve this may be readily determined by the skilled person for any vessel/agitator combination by routine experimentation 2. The pH is adjusted to a range of 2 to 6, in particular to 4 to 5.5 and more particularly to 4.5 to 5.0, As is known from sol-gel process chemistry, increasing the pH promotes the polycondensation of inorganic precursors, whereas the rate of polycondensation increases with increasing pH and temperature. The adjustment may be carried out at room temperature, but in a particular embodiment, it is carried out at elevated temperature. This may be up to 90°C, but particular embodiments are 75°C and 60°C.

The pH and temperature of the solution are key parameters for controlling the rate of gelation of the aqueous phase; this can be seen in a specific case in Example 2 hereinunder, but the goal is to achieve at this stage a primary emulsion that is chemically and physically stable for from 1-2 hours. The pH and temperature conditions needed to achieve this may be determined in each case by routine experimentation.

In this particular case (use of inorganic ethoxylate), reaction of the alkoxide with water will produce ethanol -no ethanol is produced by using any of the other precursors. It is essential that some, but not all of this ethanol be retained. The .. ethanol formed during this hydrolysis step is partially removed by distillation until the residual amount of ethanol is between 15 and 30% by weight for an alkoxide hydrolysed at 50% in water as measured by gravimetry * * ****

S

* S'S..

* 1 The rate of tetra-alkoxy silane polycondensation increases drastically when the pH : : reaches the range 4 to 6. In this pH range, the precursor polycondensation starts to occur during step 2.

3. The system is then kept for 5 to 120 minutes, particularly 10 to 60 minutes and more particularly 15 to 30 minutes under stirring. During this step, an oil-in-water sluny is formed with the continuous aqueous phase comprising both hydrophilic polymer and partially poly-condensed hydrolyzed silica precursor.

4. The resulting slurry is added into a second active under gentle stirring in the presence of an active-soluble polymer surfactant to form an oil-in-water-in-oil emulsion. The shear conditions should be such that the final droplet size is no smaller than the droplet size hereinabove mentioned. This may be readily determined in each case by routine experimentation.

5. Polycondensation is continued under gentle mixing for a duration exceeding 30 minutes, particularly 1 hour and more particularly 1.5 hours, to form a slurry of microbeads comprising a multitude of droplets of inner, encapsulated active phase, dispersed in the outer, continuous active phase. In general, by this time, the polycondensation is sufficiently completed to provide the desired delivery system.

However, it is possible that polycondensation continue after this limit, without this in any way affecting the performance of said delivery system.

Adjusting the pH is especially important for the quality and performance of the delivery system hereinabove described. If the rate of polycondensation is too fast, then the aqueous phase gels within a few minutes, making impossible the dispersion of the pre-emulsion into the second oil phase. Conversely, if the polycondensation is too slow, then destabilization of the multiple emulsion may occur, making the encapsulation inefficient. It has been found that the optimal pH range is between 4.5 and 5, and the optimal temperature range is I...

.. : between 20 °C and 60 °C. Beyond these ranges, the polycondensation kinetics are difficult 20 to control. **.e * .

For stabilisation of the active-water-active multiple emulsion of Stage 4, the presence of S. .5.5 * suitable nonionic active-soluble polymer emulsifiers is required. These should have a : * : hydrophobic to lipopilic balance (HLB) of lower than 10, more particularly lower than 5.

Any such emulsifier may be used, a particular type being a polyQropylene oxide-b-ethylene oxide) block copolymer. Typical commercial materials are those available from BASF under the Trade Mark Pluronic.

The slurry has typically 20 to 60% solid content, and more typically 30 to 55% solid content, where the term "solid content" refers to the total weight of encapsulated material and encapsulating matrix, i.e. the total weight of encapsulated active, encapsulating matrix and water comprised in this encapsulating matrix. The average size of the microbeads may range between 10 micrometer to 100 micrometers, depending on the mixing shear stress applied to the system during microbead formation, as is known by the skilled person. The selection of the most appropriate microbead size range and size distribution depends on the application envisioned, and it may be readily determined. In the case where the microbeads are used in laundry products, it has been found that a size range of from 1 to 60 micrometers offer optimal performance in terms of deposition and olfactive impact.

The inner encapsulated active to outer non-encapsulated active weight ratio is typically between (1:5) and (2:1), and preferably between (1:4) and (1:1).

Hence, the typical composition of the delivery system is: -25 -90 %, preferably 30 to 70 %, most preferably to 40 to 60 % outer, non-encapsulated active phase, and -5 -40 %, preferably 8 to 35 %, most preferably 10 to 30 % inner encapsulated active phase, and -40 %, preferably 10 to 35 %, most preferably 15 to 30 % hydrated encapsulating matrix.

: in which the hydrated encapsulating matrix further comprises: * ** * * ** 20 -ito 25 %, preferably 5 to 20%, most preferably 7.5 to 15 % hydrophilic **** polymer and -1 to 25 %, preferably 5 to 20 %, most preferably 7.5 to 5 o,/ hydrolyzed inorganic precursor * 25 -Deionized water to make 100% As can be seen from the above, the encapsulating matrix contains an appreciable amount of water. This water may be optionally removed from the system at some point of the silica network formation, especially at the end of this process, by treating the multiple emulsion with a water absorbent. Such dehydrated delivery system constitutes a further specific embodiment.

Water absorbents are well known to the art and include adsorbents, such as silica gel, zeolites diatomaceous earth, sodium and calcium bentonites, sepiolites, illite and kaolinite, aluminosilicates, cyclodextrins, activated charcoals; hygroscopic salts, such as calcium chloride, magnesium sulphate; super-absorbing polymers, such as polyacrylates, polyacrylamides or sulfonated polystyrene. Preferably, the slurry is directly sprayed onto the water absorbent to form a solid material in powder or granulate form, which can be then used as such in various applications, as exemplified below.

As mentioned hereinabove, the composition of the inner perfume phase may be different from that of the outer perfume phase, allowing programmed release of different fragrances as a function of time. For example, in the context of a laundry care product application, it may be of interest to retard the release of the most volatile odorants of the perfume by encapsulating these odorants in the inner phase of the delivery system.

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, *Ss* * 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). * * S...

* Particular examples of fragrance components that are useful include (but are not limited to) :.:::. AgrumexTM, AldronTM, AmbrettolideTM, AmbroxanTM, benzyl cinnamate, benzyl . 25 salicylate, BoisambreneTM, cedrol, cedryl acetate, CelestolidelM/CrysolideTM, CetaloxTM, citronellyl ethoxalate, FixalTM, FixolideTM, GalaxolideTM, Guaiacwood Acetate, cis-3-hexenyl salicylate, hexyl cinnamic aldehyde, hexyl salicylate, Iso E Super1M, linalyl benzoate, linalyl cinnamate, linalyl phenyl acetate, JavanolTM, methyl cedryl ketone, MoskeneTM, Musk, Musk Ketone, Musk Tibetine, Musk Xylol, Myraldyl Acetate, nerolidyl acetate, NovalideTM, OkoumalTM, para-cresyl caprylate, para-cresyl phenyl acetate, Phantolid, phenyl ethyl cinnamate, phenyl ethyl salicylate, Rose Crystals, RosonelNi, SandelaTM, tetradecariitrile, ThibetolideTM, TraseolideTM, Trimofix 0TM 2-methyl pyrazine, acetaldehyde phenylethyl propyl acetal, acetophenone, nonenylic aidhyde, allyl amy! glycolate, ally! caproate, amy! butyrate, aldehyde anisique, benzaldehyde, benzyl acetate, benzyl acetone, benzyl alcohol, benzyl butyrate, benzyl formate, benzyl iso-valerate, benzyl methyl ether, berizyl propionate, Bergamyl Acetate, butyl acetate,camphor, 3-methyl-5-propyl-2-cyclohexenone, cinnamic aldehyde, cis-3- hexenol, cis-3-hexenyl acetate, cis-3-hexenyl formate, cis-3-hexenyl iso-butyrate, cis-3- hexenyl propionate, cis-3-hexenyl tiglate, citronella!, citronellol, citronellyl nitrile, 2-hydroxy-3-methyl-2-cyclopenten-1-one, cuminic aldehyde, Cyclal CTM, acetic acid (cycloheyloxy)-2-propenylester, damascenone, aipha-damascone, beta-daniascone, decahydro beta-napthyl formate, dietliyl inalonate, dihydro-jasmone, dihydro-linalool, dihydro-myrceno!, dihydro-terpineol, dimethyl anthranilate, dimethy! benzy! carbinol, dimethyl benzy! carbinyl acetate, dimethyl octenone, DimetolTM, dimyrcetol, estragole, ethy! acetate, ethyl aceto-acetate, ethyl benzoate, ethyl heptoate, ethyl linalool, ethyl salicylate, ethyl-2-methyl butyrate, eucalyptol, eugenol, fenchyl acetate, fenchyl alcohol, 4-phenyl-2,4,6-trimethyl 1,3 -dioxane, methyl 2-octynoate, 4-isopropylcyclohexano!, 2-see-butylcyclohexanone, styralyl acetate, geranyl nitrile, hexyl acetate, alpha-ionone, iso-amyl acetate, iso-butyl acetate, iso-cyclocitral, dihydroisoj asmone, iso-menthone, iso-pentyrate, iso-pulegol, cis-jasmone, laevo-carvone, phenylacetaldehyde glycerylacetal, carbinic acid 3 -hexenyl methyl ether, 1 -methyl-cyclohexa-I,3-diene, linalool, linalool oxide, 2-ethyl * ethyl ester pentanoate, 2,6-dimethyl-5-heptenal, menthol, menthone, methyl acetophenone, * 20 methyl amyl ketone, methyl benzoate, alpha-methyl cinnamic aldehyde, methyl heptenone, methyl hexyl ketone, methyl para cresol, methyl pheny! acetate, methyl salicylate, Nera!, Nerol, 4-tert-pentyl-cyclohexanone, para-creso!, para-cresyl acetate, para-t-butyl * S* Se * cyclohexanone, para-toluyl aldehyde, phenyl acetaldehyde, phenyl ethyl acetate, phenyl ethyl alcohol, phenyl ethyl butyrate, phenyl ethyl formate, phenyl ethyl iso butyrate, :. 25 pheny! ethyl propionate, phenyl propyl acetate, pheny! propyl aldehyde, tetrahydro-2,4- dimethyl-4-pentyl-furan, 4-methy!-2-(2-methyl-1 -propenyl)tetrahydropyran, 5-Methyl-3-heptanone oxime, styralyl propionate, styrene, 4-methylphenylacetaldehyde, terpineol, terpinolene, tetrahydro-linalool, tetrahydro-rnyrcenol, trans-2-hexenal, verdyl acetate and Viridine.

In a particular embodiment, the encapsulated fragrance comprises at least 70 wt% of fragrance components having a loss factor higher than 102 Pa ppm, most preferably higher than i0 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) 1-405. **. * * * ** S **.*

Particular fragrances having high loss factor include (but are not limited to) 2-methyl pyrazine, acetaldehyde phenylethyl propyl acetal, acetophenone, nonenylic aldhyde, allyl S...

amyl glycolate, allyl caproate, amyl butyrate, aldehyde anisique, benzaldehyde, benzyl *Se�.

* acetate, benzyl acetone, benzyl alcohol, benzyl butyrate, benzyl formate, benzyl iso- ::. valerate, benzyl methyl ether, benzyl propionate, bergamyl acetate, autyl acetate, camphor, * . 25 3-methyl-5 -propyl-2-cyclohexenone, cinnamic aldehyde, cis-3 -hexenol, cis-3 -hexenyl acetate, cis-3-hexenyl formate, cis-3-hexenyl iso-butyrate, cis-3-hexenyl propionate, cis-3- hexenyl tiglate, citronellal, citronellol, citronellyl nitrile, 2-hydroxy-3 -methyl-2- cyclopenten-1-one, cuminic aldehyde, Cyclal C, acetic acid (cycloheyloxy)-2-propenylester, damascenone, alpha-damascone, beta-damascone, diethyl malonate, dihydro jasmone, dihydro linalool, dihydro myrcenol, dihydro terpineol, dimethyl anthranilate, dimethyl benzyl carbinol, dimethyl benzyl carbinyl acetate, dimethyl octenone, dimetol, dimyrcetol, estragole, ethyl acetate, ethyl aceto acetate, ethyl benzoate, ethyl heptoate, ethyl linalool, ethyl salicylate, ethyl-2-methyl butyrate, eucalyptol, eugenol, fenchyl Acetate, fenchyl alcohol, 4-Phenyl-2,4,6-trimethyl I,3-dioxane, methyl 2-octynoate, 4-isopropylcyclohexanol, 2-sec-butylcyclohexanone, styralyl acetate, geranyl nitrile, hexyl acetate, alpha-ionone, iso-amyl acetate, iso-butyl acetate, iso-cyclocitral, dihydroisojasmone, iso-menthone, iso-pentyrate, iso-pulegol, cis-jasmone, laevo carvone, phenylacetaldehyde glycerylacetal, carbinic acid 3 -hexenyl methyl ether, 1-methyl-cyclohexa-1,3 -diene, linalool, linalool oxide, 2,6-dimethyl-5 -heptenal, menthol, menthone, methyl acetophenone, methyl amyl ketone, methyl benzoate, methyl cinnamic aldehyde alpha, methyl heptenone, methyl hexyl ketone, methyl para-cresol, methyl phenyl acetate, methyl salicylate, neral, nero!, 4-tert-pentyl-cyclohexanone, para-cresol, para-cresyl acetate, para-t-butyl cyclohexanone, para-tolyl aldehyde, phenyl acetaldehyde, phenyl ethyl acetate, phenyl ethyl alcohol, phenyl ethyl butyrate, phenyl ethyl formate, phenyl ethyl iso-butyrate, phenyl ethyl propionate, phenyl propyl acetate, phenyl propyl aldehyde, tetrahydro-2,4-diniethyl-4-pentyl-furan, 4-methyl-2-(2-methyl-1 -propenyl)tetrahydropyran, 5-methyl-3 -heptanone oxime, styralyl propionate, styrene, 4-methylphenylacetaldehyde, terpineol, terpinolene, tetrahydro linalool, tetrahydro myrcenol, trans-2-hexenal, and ViridineTM.

In a further specific embodiment, the fragrance components may have an odour value * * higher than 10'OOO. The odor value is defined as the standard headspace concentration **** *.. 20 HS,° of odorant in thermodynamic equilibrium with this odorant in the standard state (278.15 K, I atmosphere), expressed in microgram / I headspace, divided by the olfactory **S.

* ** threshold of this odorant (in microgram! 1 headspace) as measured by olfactometry. The standard headspace concentration is related to the vapor pressure of the pure ingredient by the equation: S.. I-IS°

RT

where m,' is the molar mass of the odorant, R is the gas constant, T the absolute temperature given in Kelvin and p the.standard vapor pressure given in atmosphere.

Precursor of fragrance components may also be provided in fragrance materials in the present invention. Precursors are compounds that, upon cleavage under activating conditions such as light, enzymes, elevated temperature or acidic or alkaline pH-values, provide compounds having fragrance characteristics.

Furthermore, other organoleptic materials may be used in admixture with fragrance ingredients, for example, odour-masking agents, insect repellents and the like. In addition, the fragrance may also include any of the standard non-fragrance ingredients that are used in fragrance formulations. Non-limiting examples of these include solvents (such as dipropylene glycol and miglyol), surfactants, oils, waxes and the like. These may be used in the usual art-recognised quantities In a specific embodiment, the composition of the inner perfume (flavour) phase may be different from that of the outer perfume (flavour) phase, allowing programmed release of different impressions as a function of time. For example, in the context of a laundry care product application, it may be of interest to retard the release of the most volatile odorants of the perfume by encapsulating these odorants in the inner phase of the delivery system.

A particular advantage of the microbeads hereinabove described is their combination of three very commercially desirable properties: (i) the ability to retain perfume for long **,* * : periods in storage, even at elevated temperatures; (ii) high frangibility, allowing ease of *** * ... 20 release of the perfume when required; (iii) controlled porosity allowing slow diffusion of the perfume when the capsule is present in the dry state on a substrate, or rewetted under * * SI..

the action of ambient humidity or sweat, and (iv) free of environmentally questionable ** S* S * residual chemicals. In this, they are clearly superior to known microcapsules, which hardly combine such beneficial properties in a satisfactorily way.

*.. 25 * The dispersion of microbeads hereinabove described is 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.

There is therefore provided a personal care product, a household product, a washing product or a cleaning product, comprising a product base and a dispersion of microbeads as hereinabove defined.

By "product base" is meant the combination of all ingredients other than the fragrance that allow the product to fulfil its desired function. These will vary, depending on the nature of the product and the desired effect, but non-limiting examples of such ingredients include surfactants, detergents and detergent builders, solvents, fillers and extenders, abrasives, viscosity modifiers, flow control agents, pigments, dyestuffs and other colouring matters, waxes, emollients, medicinal compounds, and cooling compounds. These may be combined in art-recognised quantities.

There now follows a series of examples that serve to illustrate specific particular embodiments and which are not intended to be in any way restrictive.

Example 1

Preparation of a delivery system This procedure relates to the case of tetra-ethoxy silane (TEOS) and MowiolTM 4/88 (olyvinyl alcohol). However, it can be applied to other water-soluble inorganic precursors and hydrophilic polymers with only minor alterations that can easily be made by the skilled person. * . . a. *

*,** 20 1.1 Preparation of polyvinyl alcohol (PVOH) solution A *S.S g MowiolTM 4/88 (ex Kuraray) is dissolved at 80°C in 80 g water adjusted to a pH of 2 * by addition of HC1 25%, to form a 20% PVOH solution. * *1 * a S...

*. 25 1.2 Preparation of hydrolyzed tetra-ethoxy silane (TEOS) solution B 50g of TEOS (ex Fluka) is dissolved in 50g solution of hydrochloric acid having apH of 2 under vigorous stirring using a magnetic stirrer until the hydrolysis of TEOS is completed.

The ethanol formed during this hydrolysis step is partially removed by distillation until the residual amount of ethanol is 25% as measured by gravimetry.

1.3 Preparation of the continuous oil phase g PluronicTM LiOl (ex BASF) is dissolved at room temperature into 95g of a perfume mixture as set out in Table 1 below. This will provide the continuous phase.

Table I Continuous phase perfume composition Fragrance ingredient Verdox'TM 4.86 anisic aldehyde 0.73 Benzophenone 1.46 benzyl acetate 0.59 benzyl salicylate 2.88 beta-ionone 18.85 beta-pinene 0.45 brassylate ethylene 0.59 cis-3-hexenyl salicylate 0.45 Coumarine 0.59 cyclal C 2.25 -.

Eugenol 0.59 * * 0*** GalbanonelM 3.47 ** IIabano1ideTM 0.59 *..* *. HedioneTM 0.59 hexyl acetate 1.73 hexyl cinnamic aldehyde 5.76 Iso E super1M 11.01 IsoraldeinelM 5.10

TM

Lilial 5.83 Linalol 1.35 linalyl acetate 1.46 Nectary!TM 3.47 Oranger 2.88 beta-decalactone phenyl ethyl acoho! 2.32 prenyl acetate 1.04 RosacetolTM 1.15 RosaphenTM 0.87 ThibetolideTM 0.59 verdyl acetate 11.28 verdyl propionate 0.87 VertofixTM 0.87 100.00 *S.* .. : 1.4 Preparation of primary emulsion S..' * , S...

g of solution A is mixed with 50 g of solution B, to form the water phase of a primary emulsion, 33.4 g of disperse phase perfume test mixture (see Table 2 below) is added to *5**S* * 66.6 g of this water phase under high shear mixing, using a propeller mixer operating at : . 1100 rpm and with a propeller to vessel diameter ratio of 0.3. The pH of the reaction S...

medium is adjusted to pH 4.5 with 10 % sodium hydroxide solution, in order to initiate the polycondensation of the TEOS.

Table 2 Encapsulated perfume composition Fragrance ingredient Verdox1M 4.86 anisic aldehyde 0.73 Benzophenone 1.46 benzyl acetate 0.59 benzyl salicylate 2.88 beta-ionone 18.85 beta-pinene 0.45 brassylate ethylene 0.59 cis-3-hexenyl salicylate 0.45 Coumarine 0.59 cyclal C 2.25 Eugenol 0.59 GalbanoneTM 3.47 HabanolideTM 0.59 HedioneTM 0.59 hexyl acetate 1.73 : hexyl cinnamic aldehyde 5.76 Iso E superTM 11.01 IsoraldeineTM 5.10

I

S.....

* Li1ia1 5.83 * S. * I Linalol 1.35

S **

linalyl acetate 1.46 NectarylTM 3.47 Oranger 2.88 beta-decalactone phenyl ethyl acohol 2.32 prenyl acetate i.04 RosacetolTM 1.15

L TM

1s..osapllen 087 ThibetolideTM 0.59 verdyl acetate 11.28 verdyl propionate 0.87 VertofixTM 0.87 100.00 1.5 Preparation of the oil-in-water-in-oil multiple (secondary) emuljpii Immediately after the pH of the primary emulsion has been adjusted to 4.5, 45 g primary emulsion is added slowly, over a period of 5 minutes, to 55 g continuous phase perfume test mixture, as prepared in 1.3 above, under low shear stirring, using an anchor blade mixer operating at 200 rpm and using a blade to vessel diameter ratio of 0.9. The stirring is maintained for 1.5 hours at room temperature. * S*S

: 10 The multiple emulsion obtained by the aforementioned process comprises 15% *..

encapsulated perfume, 30% (hydrated) encapsulating matrix and 55% continuous phase perfume.

*****.

* Example 2

: *. 15 Optimisation of the pH of reaction S...

S S..

S

50g of PVOH solution at pH 2 according to Example 1.1 and SOg of hydrolyzed TEOS according to Example 1.2 are mixed together and divided into 5 identical portions. The pH of each portion is adjusted with sodium hydroxide to the values as shown in Table 3. The rate of TEOS polycondensation is assessed by monitoring the time at which a gel phase occurs.

Table 3 Role of pH on TEOS polycondensation kinetics Sample 1 2 3 4 5 pH of the solution 2 3 4 5 6 Onset of gel formation >24H >24H 3H30 30mm 5mm As can be seen from Table 3, increasing the pH above 4 accelerates significantly the polycondensation of TEOS. In the present case, the optimal pH range for the present invention is between 4 and 5.

Example 3

Influence of ethanol The procedure of Example 1 was repeated using different solutions of hydrolysed TEOS.

Their differences were based on the duration of the distillation step, which allows the control of the amount of ethanol in the solution.

50g of TEOS (ex Fluka) is dissolved in 50g solution of hydrochloric acid having a pH of 2 under vigorous stirring using a magnetic stirrer, until the TEOS is completely hydrolysed.

This solution is distilled at 65°C under primary vacuum. The weight loss measured as a a...

function of time is reported in Table 4. It may be assumed that the vapours released are *5 composed of 96% of ethanol. This allows the determination of the percentage of ethanol in S.....

* . the solution.

* *. 20 * . S Table 4 Residual ethanol in the hydrolysed TEOS solution Time (mm) Weight loss (%) % ethanol Sample 0 0 44.2 1 20.7 31 2 361 16 3 These measurements are used to prepare four different multiple emulsions according to the process described in Example 1, with solutions containing respectively 44.2, 31, 16 or 3% of ethanol (see Table 4).

The microbeads obtained are observed by microscopy. By pressing the microbeads between two slides, it is easy to determine whether the matrix is soft or hard.

For sample 1, the matrix surrounding the encapsulated oil droplets is soft and no gel state is observed even after several hours of aging. On the other hand, the reproducibility of the particles of sample 4 is poor, because the matrix gels too quickly, and the particles obtained are irregular in shape. The particles obtained for samples 2 and 3 are regular in shape and stable after storage.

Example 4

Optitnisation of the polymer-inorganic precursor ratio One role of the polymer in the matrix is to prevent the syneresis of the inorganic gel, which is characterised by the exudation of water from the gel. The optimal ratio of polymer and * :. inorganic precursors is that for which no syneresis occurs. The optimal ratios are *: 20 determined by constructing the phase diagram of the polymer-inorganic precursor system. * S..

Each point of the phase diagram is associated to a mix of polymer and inorganic precursor. I...

The description of the aspect of the sample is done after 48H of storage of the samples at 37°C, according to the following guidelines: * *.

-"gel" : the mix forms an homogeneous gel S..

-"syneresis" : the mix is biphasic with a large amount of water released -"limit" : the mix is a homogeneous gel with a thin layer of water on top of it.

The phase diagram of hydrolysed TEOS solution and Mowiol 4/88 is shown at Figure 1.

The optimal ratios of Mowiol 4/88 and TEOS correspond to the domain of the phase diagram for which the state "gel" is indicated.

The procedure of Example 1 is repeated using the TEOS-Mowiol 4/88 ratios shown in Table 5. These ratios are selected according to the phase diagram of hydrolysed TEOS-Mowiol 4/88 of Figure 1, to determine the influence of the macroscopic stability of the matrix on the multiple emulsion stability.

Table 5 Stability of the emulsions regarding the stability of the matrix Sample 1 2 3 4 5 6 TEOS (%) 25 25 12.5 12.5 5 5 Mowiol4/88 7.5 10 2.5 10 10 2 (%) _____ ______ ______ _____ ______ ______ Unperfumed Syneresis Syneresis Syneresis Hom* Hom* Syneresis matrix Multiple stable stable unstable stable unstable unstable emulsion *Hom homogeneous The presence of the continuous phase and encapsulated fragrances moves the domains of * stability of the multiple emulsion to higher amounts of inorganic precursor. * * S...

Example 5 *.**

Variation of the load of encapsulated fragrance S..... * S

* The procedure of Example 1 is repeated using different percentages of encapsulated S...

perfume, as reported in Table 6. For all the samples reported here, the oil-in-water-in-oil multiple emulsion structure is obtained.

Table 6 Variation of the encapsulated fragrance loading Sample 1 2 3 4 5 encapsulated 13.3 15 16.4 17.6 18.8 fragrance (%) matrix (%) 26.7 25 23.6 22.4 21.2 continuous phase 60 60 60 60 60 fragrance (%)

Example 6

Variation of ratio of encapsulated fragrance and continuous phase fragrance The procedure of Example I is repeated using different ratios of encapsulated fragrance and continuous phase fragrance, as reported in Table 7. For both samples reported here, the oil-in-water-in-oil multiple emulsion structure is obtained.

Table 7 Variation of the inner oil to outer oil ratio Sample 1 2 encapsulated fragrance (%) 13.3 31 :::: matrix(%) 26.7 31 .. continuous phase fragrance (%) 60 37 S... **SS

Example 7

Use of different polymers and concentrations

: *** Example 7-1 Se..

The procedure of Example 1 was repeated using Mowiol 15/79 as the hydrophilic polymer.

In the Table 8 we reported the different concentrations of polymer and TEOS used.

Table 8 Multiple emulsions prepared with Mowiol 15/79 Sample 1 2 3 4 5 TEOS(%) 25 25 10 10 15 Mowiol 15/79 (%) 2.5 7.5 7.5 10 10 Comments unstable unstable stable stable borderline By "borderline" is meant that a stable emulsion is only sometimes achieved.

Example 7-2

The procedure of Example I was repeated using Mowiol 3/96 as the bydrophilic polymer.

In Table 9, different concentrations of polymer and TEOS are exemplified.

Table 9 Multiple emulsions prepared with Mowiol 3/96 Sample 1 2 TEOS (%) 20 10 Mowiol 3/96 (%) 7.5 7.5 Comments stable Difficult to form because of high inner droplets size Example 8 -Application in shampoo Using the procedure of Example 1 with Mowiol 15179 (ex Kururay) as the hydrophilic polymer, three samples of multiple emulsions are prepared for evaluation of the olfactory benefit in shampoo. S... * . .

S

*. 15 Table 10 Samples composition tested in shampoo application S.. * _______________ _____________ _______________ Sample 1 2 3 *SeS ______________________________ ______________ _____________ Hydrolysed TEOS 25% lOg lOg lOg *:: Mowiol 15-79 at 15% lOg lOg lOg * .. . Perfume lOg 20g 20g * * . Primary Myghol Og Og lOg * emulsion ______________________ *S.

* Total 30g 40g 50g Free perfume 11.4g 11.4g 11.4g Pluronic LiOl 0.6g 0.6g 0.6g Multiple emulsion primary emulsion 8g 20g 20g % of multiple emulsion in shampoo 031 0.75 0.83 The perfumed samples are prepared with a 0.5% perfume percentage in a standard shampoo base. The olfactory benefit is evaluated according to the following protocol: 5g of shampoo is prepared in a 250mL beaker A hair tress is wet with 30 g of water at 35°C in a 250m1 beaker 5g shampoo is added to the wet hair tress The hair tress and shampoo are mixed with a glass spatula and allowed to sit for 10 minutes.

The tress is rinsed with tap water (T = 35°C) and the shampoo washed out by squeezing the hair tress between 2 fingers, 20 times on each side of the tress The tress is placed between 2 folds of absorbing paper and squeezed The tress is brushed.

The olfactory evaluation is done on wet and dry hair, using the following scale * O-Noodour * I -Odour is barely perceivable * 2 -Weak fragrance but perceivable * 3 -Easily perceivable * 4-Strong * 5 -Very strong *: :: : and the results are shown in Figure 2 As illustrated by the results in Figure 2, the samples 1 and 3 have a noticeable olfactory benefit compared to the shampoo perfumed with conventional liquid perfume addition. * * ****

Example 9 -Application in tooth paste * * * : * Using the procedure of Example 1, two flavour oils (mint and lemon) are used as the * fragrance phases to prepare samples for evaluation of the olfactory benefit in tooth paste.

0.2% of modified cellulose (EthocelTM, ex Dow) was added to the encapsulated fragrance -this is a conmion method of helping the formation of the primary emulsion by increasing the viscosity of the encapsulated oil.

Table 11 Samples composition tested in tooth paste application Sample 1 2 Encapsulated flavour Mint Lemon Continuous phase flavour Lemon Mint The perfumed samples are prepared at 0.5% perfume in a standard toothpaste base.

According to visual observations made under the microscopy on the perfumed samples S stored for one week at 37°C, the microbeads are stable.

The toothpastes are then tested by a taste panel, by brushing. Both gave the initial flavour of the continuous phase flavour, followed by the perception of the encapsulated flavour as brushing released it. This change was more noticeable with Sample 1. * . S S. S S'S. * . S... *5*5 * . *S.*

*IS*SS * S * S. * S * *.

S 5.

S

Claims (8)

1. CLAIMS: 1. A dispersion in a non-aqueous continuous phase of active-containing microbeads, the microbeads comprising a plurality of droplets of active within a matrix, the matrix being a hybrid material comprising both organic and inorganic materials, the organic material being a hydrophilic material selected from poly(vinyl alcohol), poly(carbohydrates) and poly(alkylene glycols), and the inorganic material being an oxide that forms a continuous network through the organic material.
2. 2. Dispersion according to claim 1, in which the hydrophilic organic material of the matrix is selected from the group consisting of -Poly(vinyl alcohol) having hydrolysis grades ranging from 50 to 99%, and including cationic-modified and aceto-acetylated polyvinyl alcohols; -Poly(carbohydrates), including cellulose (including cationic cellulose), hydrolyzed starch, and organic gums, such as gum Arabic and locust bean gum, -Poly(alkylene glycols), particularly polyethylene glycol.

   * : : :
3. 3. Dispersion according to claim 2, in which the hydrophilic organic material is a polyvinyl alcohol having a degree of hydrolysis from 50 to 80%, optionally admixed with a polyvinyl alcohol having a degree of hydrolysis from 80 to 99%,. ** ** * S I...

   * :
4. 4. Dispersion according to claim 1, in which the inorganic material is selected from: * ** -Silicon alkoxides of the general formula Si(OR)4, where R is a alkyl radical, and * : : 25 partially or totally hydrolyzed forms of these silica alkoxides, *5* -Inorganic precursors having the formula M(R')n(R")m, where M is a metal, selected from aluminium, titanium, vanadium, or zirconium or a metalloid, selected from silica or germanium, R' is an alkoxy moiety of formula O-R", where R" is selected from lactate, alkyl or aryl residues; R" is a halogen; and n and m are integers having values 0, 1, 2, 3 or 4.
5. 5. A microbead-based active delivery system, comprising a dispersion of active-containing nuicrobeads according to claim 1.
6. 6. A delivery system according to claim 5, in which the continuous phase comprises active.
7. 7. A method of preparing a microbead active delivery system, comprising the steps of a. preparing a mixture of the active to be encapsulated and a matrix precursor; b. dispersing this mixture in an active continuous phase; and c. causing the matrix precursor to form an encapsulating matrix; characterised in that the matrix precursor comprises both inorganic and organic components, the organic component being an aqueous solution of a material selected from poly(vinyl alcohol), poly(carbohydrates) and poly(alkylene glycols), and the inorganic material being an aqueous material that forms a continuous oxide network through the organic material, the water content of the matrix being 25% to 85% by weight of water. * * * ** a
8. S... * . S... *SSS * . *5**S***s 51 * S * S. * . . *.SS