MICROCAPSULES AND ENCAPSULATION THEREOF

FIELD OF INVENTION

The invention relates to a formaldehyde-free polymeric shell and lipophilic active-core material based microcapsules, with improved thermal stability. The microcapsules with cross-linked acrylate vinyl copolymer shell imparts benefits of high heat stability that allows the microcapsule shell to break only at a temperature which is above 250 °C, and the shell prevents leaching of core for a longer time at higher temperature (120 °C for 30 minutes). This enables the microcapsules to be suitable for applications at high temperatures along with applications at ambient conditions. The present invention also relates to the process of manufacturing microcapsules.

BACKGROUND ART

Most live on and rinse off formulations including cosmetic formulations contain fragrances or perfumes in order to confer a pleasant smell to the formulation itself or to the surface, be it textile, skin or hair, onto which the formulation is applied. The fragrances or perfumes are often compounds which are sensitive to various chemicals and to oxidation and hence the need for encapsulation. Also consequently, unwanted interactions with other ingredients of the formulations such as surfactants may lead to an alteration of the fragrance note. In addition, fragrances or perfumes are mostly highly volatile. As a result, a large part of the quantity of fragrance originally added to the formulations gets volatile before the time of application and the remaining quantity of fragrance actually applied onto the treated surface also evaporates within a short time. To overcome these problems, it has already been proposed to incorporate the fragrances or perfumes in microcapsules into the formulations. These microcapsules enable the valuable fragrance or perfume to be distributed relatively homogeneously in a formulation, without having to expose it to the other constituents during storage. Suitable selection of the shell of the capsule also allows effects to be achieved in this way such as retarded release or release on demand upon rubbing or r e l e a s e a t h i g h e r t e m p e r a t u r e .

WO2014/189980 A1 describes a population of encapsulated benefit agents having a population diameter coefficient of variation from 6 % to 50 , preferably from 8 % to 35 , more preferably from 12 % to about 25, said population of encapsulated benefit agents comprising encapsulated benefit agents having a mean diameter of from 3 micrometers to 300 micrometers, preferably from 5 micrometers to 240 micrometers, more preferably from 10 micrometers to 120 micrometers, said encapsulated benefit agent comprising a core and a shell that encapsulates said core, said shell comprising a polymer, preferably a film forming polymer, said shell having a thickness of from 0.5 micrometers to 15 micrometers, preferably from 1 micrometer to 8 micrometers, more preferably from 1.5 micrometers to 6 micrometers and a shell thickness coefficient of variation from 2 % to 30, preferably from 4 % to 25 , more preferably from 6 % to 20. Also encompasses a population of encapsulated benefit agents according to Claim 1 wherein said shell material comprises, poly(vinyl alcohol), poly(vinyl acetate), poly(vinyl pyrrolidone), poly(vinyl acetate phthalate), vinyl acetate neodecanoic acid co- polymer, vinyl acetate ethylene co-polymer, vinyl acetate crotonic acid neodecanoate co-polymer, vinyl acetate crotonic acid co-polymer, vinyl acetate butyl maleate co-polymer, cellulose acetate, cellulose acetate phathalate, ethyl cellulose, hydroxyl propyl methyl cellulose phathalate, cellulose acetate butyrate, vinyl pyrrolidone vinyl acetate co-polymer, poly(styrene-comaleic acid) isobutyl ester, poly(styrene-co-butadiene), poly(styrene-co-acrylic) and mixtures thereof, but does not relate to microcapsules with high thermal stability.

WO2012/162742 (also published as AU2011902127, EP2714817, CN104053729, US9339781B2, AU2012262664B2, NZ618219, or CA2837897) teaches a method of preparing an aqueous dispersion of polymer encapsulated particulate material, the method comprising: providing a dispersion of the particulate material in a continuous aqueous phase, the dispersion comprising ethylenically unsaturated monomer and a stabiliser for the particulate material; and polymerising the ethylenically unsaturated monomer by non-living free radical polymerisation to form polymer that encapsulates the particulate material, thereby providing the aqueous dispersion of polymer encapsulated particulate material; wherein polymerisation of the ethylenically unsaturated monomer comprises:

(a) polymerising a monomer composition that includes ionisable ethylenically unsaturated monomer so as to form a base responsive water swellable non-living

polymer layer that encapsulates the particulate material; and

(b) polymerising a monomer composition that includes non-ionisable ethylenically unsaturated monomer so as to form an extensible, water and base permeable non-living polymer layer that encapsulates the base responsive water swellable polymer layer.

WO2012/162742 also teaches polymer encapsulated particulate material attained, the particulate material being encapsulated by a base responsive water swellable non-living polymer layer comprising polymerised residue of ionisable ethylenically unsaturated monomer, wherein the base responsive water swellable non-living polymer layer is encapsulated by an extensible, water and base permeable non-living polymer layer that comprises polymerised residue of non-ionisable ethylenically unsaturated monomer, but does not relate to microcapsules with high thermal stability.

WO2017004339 (A1) teaches a consumer product comprising a composition, the composition comprising: an adjunct material; a first population of microcapsules, the first population having a first median volume weighted particle size and comprising microcapsules comprising a partitioning modifier and a first perfume oil at a first weight ratio; and a second population of microcapsules, the second population having a second median volume weighted particle size and comprising microcapsules comprising the partitioning modifier and a second perfume oil at a second weight ratio; wherein the first weight ratio and the second weight ratio are different, and/or the first median volume weighted particle size and the second median volume weighted particle size are different; wherein the composition is a fabric and home care composition, thus relates to consumer product with two different microcapsule population and does not teach microcapsules with high thermal stability.

WO2005/002719 teaches a method for preparing microcapsules comprising the steps of: (a) mixing a free-radically polymerizable and ethylenically unsaturated monomer, an

emulsifier, an ultrahydrophobe, a hydrophobic material, an initiator and deionized water, to prepare a miniemulsion; and (b) polymerizing the miniemulsion to prepare the microcapsules but does not enable microcapsules with high thermal stability.

US2012076843 (A1) teaches a microcapsule comprising a capsule core and a capsule wall obtainable by a process comprising the free-radical polymerization of an oil-in-water emulsion which comprises the following constituents: 30 to 90% by weight based on the total weight of the monomers of one or more monomers (monomers I) from the group comprising C1 C24-alkyl esters of acrylic acid and/or methacrylic acid acrylic acid methacrylic acid maleic acid fumaric acid and itaconic acid; 10 to 70% by weight based on the total weight of the monomers of one or more ethylenically unsaturated crosslinkers (monomers II) where at least 10% by weight based on the total weight of the monomers I II and III is a highly branched polymeric crosslinker; 0 to 30% by weight based on the total weight of the monomers of one or more monounsaturated monomers (monomer III) which are different from the monomers I and a hydrophobic core material. But it does not teach microcapsules with high thermal stability.

WO2019/121736 teaches an encapsulated perfume composition comprising at least one core-shell microcapsule suspended in a suspending medium, wherein said at least one core-shell microcapsule comprises a core containing at least one perfume ingredient, and a shell surrounding or at least partially surrounding the core, wherein the shell comprises a thermosetting resin formed by the reaction of shell-forming materials selected from monomers, pre-polymers and/or pre- condensates, and wherein the encapsulated perfume composition comprises a polymeric stabilizer that is the reaction product of a polymeric surfactant and a silane containing a functional group capable of forming covalent bonds with the shell. But the thermal stability of the microcapsule composition as per this prior art is not disclosed.

WO2020190689 (also published as US 2020/0315931 A1) teaches a population of microcapsules comprising a capsule core and a capsule shell, the capsule shell being hydrolysable, the microcapsules made by an oil-in-water microencapsulation process comprising: a) dispersing in an aqueous phase a polymeric emulsifier and optionally, an initiator; b) dispersing in one or more oil phases: i) an initiator, and a core material, ii) a first multifunctional (meth)acrylate monomer having greater than one ester group on average in the monomer and having a hydrophilicity index of less than 20, iii) a second multifunctional (meth)acrylate monomer, the second multifunctional (meth)acrylate comprising a hydrophilic multifunctional polar monomer having a hydrophilicity index of at least 20 and said second multifunctional polar monomer comprising 50% or less of the capsule shell, wherein the first and second multifunctional (meth)acrylate monomers together comprise greater than 80% by weight of the capsule shell, iv) an acidic (meth) acrylate monomer or at least one oil soluble or dispersible simple acid or both, the acidic (meth)acrylate monomer having one or more groups which are selected from carboxy and sulfonic groups, and v) optionally from 0 to 50% by weight of an aliphatic polyester, the aliphatic polyester having two or more of acrylate or methacrylate groups; c) emulsifying the one or more oil phases into the water phase under high shear agitation to form an oil-in-water emulsion comprising droplets of the core material and oil phase monomers dispersed in the water phase; d) activating the initiator or initiators by heat or actinic radiation to react the monomers and optional aliphatic polyester thereby forming a capsule shell which is polymeric, surrounding the droplets of the emulsion. Thus, this prior art teaches multifunctional (meth)acrylate monomers as the shell wall variant that is free of involving vinyl acetate monomer but involving polyvinyl pyrrolidone together with butyl acrylate going into the microcapsule shell formation does not relate to capsules with increased thermal stability.

CN109453724A discloses a preparation method of a sustained-release microcapsule with a multi-core interior. The preparation method comprises the following steps: dispersing a suspension mixed with an acrylate polymer, a volatile organic solvent, liquid essence and porous starch into a colloid-protect reagent aqueous solution by mechanical agitation to form an oil-in-water system; then performing pressure reduction to remove the volatile organic solvent in the oil-in-water system, and conducting interfacial phase separation on the acrylate polymer, the liquid essence and the porous starch to form an acrylate polymer microcapsule wrapped with the liquid essence and the porous starch in the interior; and further adding an ethylene glycol dimethacrylate prepolymer, and performing heating curing to obtain a crosslinked acrylate polymer essence microcapsule with a multi-core interior, namely the sustained-release microcapsule with the multi-core interior. The

method is simple to operate and efficient for preparation, and wrapped essence can be released gradually, is lasting in fragrance, and can be widely applied in the fields of cosmetics, household supplies or personal care products and functional materials.

US20170211019 ( also published as WO 2017/132101A1, JP 6651637B2, o r EP3408363A1) teaches a composition comprising, based upon total composition weight: a) from about 0.01% to about 1%, of a polymeric material comprising a first polymer and a second polymer; said first polymer is derived from the polymerization of from about 5 to about 100 mole percent of a cationic vinyl addition monomer, from about 0 to about 95 mole percent of a non-ionic vinyl addition monomer, from about 50 ppm to about 1,950 ppm of a cross-linking agent comprising two or more ethylenic functions, about 0 ppm to about 10,000 ppm chain transfer agent; said second polymer being derived from the polymerization of from about 5 to about 100 mole percent of a cationic vinyl addition monomer, from about 0 to about 95 mole percent of a non-ionic vinyl addition monomer, from about 0 ppm to about 45 ppm of a cross-linking agent comprising two or more ethylenic functions, about 0 ppm to about 10,000 ppm chain transfer agent; b) from about 0% to about 35% of a cationic quaternary fabric softener active material, the iodine value of the parent fatty acyl compound or acid from which the alkyl or, alkenyl chains are derived being from about 5 to about 60; and c) a population of perfume microcapsules with the proviso that said population of perfume microcapsules comprises a microcapsule wall material comprising one or more polyacrylate polymers; said composition being a fabric and home care product. The polymer is derived by involving-(iii) an anionic monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, as well as monomers performing a Sulfonic acid or phosphonic acid functions, such as 2-acrylamido 2- methyl propane Sulfonic acid, and their salts. The perfume microcapsules comprising a microcapsule wall material essentially involving cationic vinyl addition monomer of quaternary ammonium type also does not teach any improved thermal stability of the microcapsules.

WO 2017123965 also published as US 2019/0054440 A1, AU2017207981 B2, EP3402674, CN108778730B, BR112018014242, US20190054440, JP2019505375 (JP 6938514B2), CA3011107, IN201817026022, MX2018008726 teaches A microcapsule comprising: i. a lipophilic core material, and ii. a microcapsule shell;

wherein said microcapsule shell is formed from oil-in-water emulsion polymerisation of a monomer mixture consisting essentially of: (a) greater than 70 to about 99% by weight of at least one polyfunctional ethylenically unsaturated monomer, (b) about 1 to about 30% by weight of at least one unsaturated carboxylic acid monomer or its ester, and (c) about 0 to about 30% by weight of at least one vinyl monomer.

WO2017040759 also published as CA2980193, CN107530672, AU2016317844, EP3344382, teaches an aqueous slurry composition, comprising an aqueous medium having dispersed therein oily medium-containing microcapsules, wherein the oily medium-containing microcapsules comprise an ionic acrylate copolymer shell encapsulating said oily medium. Thus teaches only acrylic polymer based microcapsules and does not involve any shell structure based on meth (acrylic)- vinyl acetate copolymer to attain thermally stable microcapsules through a distinct process. EP2397120B2 also published as WO 2011/158962, ES2597980, US9464263B2, CN102946843, BR112012032063, JP2013530253, MX344969 teaches a liquid consumer product having a density in the range from 0.900 g/cm3 to 1.400 g/cm3, preferably from 0.900 g/cm3 to 1.250 g/cm3, and which comprises core shell microcapsules wherein:

- the microcapsule shell is formaldehyde-free and is made of starting materials such that 50%-100% by weight of said materials have a density equal to or less than 1.05 g/cm3;

- the microcapsule core contains a fragrance composition, which composition comprises:

a) 20-100% by weight of at least one cyclic fragrance material with a density

greater than 0.950 g/cm3 and a ClogP in the range from 1.00 to 6.00; b) 0-50% by weight of at least one oil soluble organic compound having a density greater than 0.950 g/cm3;

c) 0-80% by weight of at least one material selected from cyclic fragrance ingredients with densities equal to or less than 0.950 g/cm3

and non-cyclic fragrance ingredients with densities which may be greater or less than 0.950 g/cm3;

where the sum of a), b) and c) equals 100%, wherein the weight ratio of core materials to shell materials is in the range from 50:1 to 1:1; and wherein the said starting materials comprise at least 50% by weight, preferably at least 60% by weight, of (meth) acrylic acid and/or (meth) acrylates; wherein the dosage of the microcapsules into the liquid consumer product is in the range from 0.01 to 10% by weight, preferably from 0.05% to 2.5% by weight, more preferably from 0.1 to 1.25% by weight of the liquid product composition, and hence teaches select density based shell wall material to encapsulate select fragrance which shell material does not involve any poly((meth)acrylate-co-vinyl acetate copolymer to lead to thermally stable crosslinked microcapsules based on a select process of polymerization.

WO2014032920A1, EP2890486B1, CN104755162B, KR1020150052046, RU2015111081, BR112015004387, ID2016/05358, RU0002639909, JP2015535858, CA2882427, 1199/CHENP/2015; MX2015002649, JP2017105791; teaches a microcapsule comprising a core of hydrophobic material composed of at least one fragrance and a microcapsule shell obtainable by the suspension polymerization of the following monomers:

(a) one or more C1-C24-alkyl ester(s) of (meth)acrylic acid (monomer A), (b) one or more bi- or polyfunctional monomers (monomer B) and (c) optionally, one or more other ethylenically unsaturated monomers (monomer C),

wherein the shear rate for the preparation of the emulsion lies in the range of from 150 to 500rpm, the stirring time for the preparation of the emulsion lies in the range of from 15 min to 180 min and an anchor-type stirring blade or a MIG- stirrer is used for the preparation of the emulsion, however does not teach any thermally stable microcapsules that can be attainable out of specific involvement of vinyl acetate monomer by avoiding the shear rates mentioned in this prior art.

WO2017/004339, US20170002301, CA2989002, CN107835681, EP3316854 B1, JP2018522976, PL3316854, IN201717045571, MX364218, JP2020073672; teaches a consumer product comprising a composition, the composition comprising: an adjunct material; a first population of microcapsules, the first population having a first median volume weighted particle size and comprising microcapsules comprising a partitioning modifier and a first perfume oil at a first weight ratio; and a second population of microcapsules, the second population having a second median volume weighted particle size and comprising microcapsules comprising the partitioning modifier and a second perfume oil at a second weight ratio; wherein the first weight ratio and the second weight ratio are different, and/or the first median volume weighted particle size and the second median volume weighted particle size are different; wherein the composition is a fabric and home care composition, and hence this prior art does not teach that by avoiding partitioning modifiers and based on only one type of microcapsules with only one fragrance type thermally stable microcapsules could be attained.

While microcapsules encapsulating actives are known in the art, there is still a need to explore for microcapsule that would have lipophilic material as core such as fragrance that would be thermally stable to break down at above 250 °C to suit high temperature applications including steaming of fabric, hair-straightening, paints, textile-processing, shoe insole making.

OBJECTS OF THE INVENTION

It is thus one object of the present invention to provide for microcapsules with lipophilic core that would be thermally stable as microcapsules so that during their applications at higher temperature the shell doesn’t break and thus prevent the loss of the lipophilic core and under any mechanical stress the shell would break to release the core/benefiting agent. It is another object of the present invention to provide for said microcapsule with lipophilic core including liquid active such as fragrance.

It is yet another object of the present invention to provide for said microcapsules synthetic process that would involve preheating/pre-polymerization of monomers/shell materials in oil phase to be yet carried out under a preparation procedure involving a single polymerization step; i.e. all the reactive monomers are copolymerize together in one step.

DESCRIPTION OF THE INVENTION

Figure 1 shows the Olfactive Performances of Microcapsule compositions.

Figure 2 shows the TGA Thermogram for Microcapsule compositions.

Figure 3 shows the Isothermal TGA Thermogram for Microcapsule compositions.

Figure 4 shows the Olfactive Performances of Microcapsule compositions after steaming for 3 minutes at 120 °C.

The present invention relates to a microcapsule comprising a lipophilic core material and a microcapsule shell wherein said microcapsule shell is formed from oil-in-water emulsion polymerisation of a mixture of monomers, more than 50 percent by weight of the mixture of monomers consisting in monomers having a density higher than 1.05, said mixture of monomers comprising a) more than 30 percent by weight of one or more of ethylenically unsaturated acid monomer(s) based on the total weight of the mixture of monomers, b) one or more monofunctional acrylate and/or methacrylate monomer(s), c) one or more multifunctional acrylate and/or methacrylate monomers, and d) vinyl acetate monomer.

In an embodiment the microcapsule is thermally stable at 250°C.

In an embodiment the microcapsule is formaldehyde-free.

In an embodiment the microcapsule is characterised in that the log P values of all the monomers comprised in the mixture of monomers range from 0.5 to 4.0.

In an embodiment the microcapsule is characterised in that the ethylenically unsaturated acid monomer(s) is selected from acrylic acid, methacrylic acid, crotonic acid, 2-carboxyethyl acrylate, glutaconic acid, 3,3-Dimethylacrylic acid, itaconic acid, maleic acid, fumaric acid or a mixture of two or more of said acids.

In an embodiment the microcapsule is characterised in that the ethylenically unsaturated acid monomer is methacrylic acid.

In an embodiment the microcapsule is characterised in that the concentration of ethylenically unsaturated acid monomers in the monomer mixture is equal or inferior to 45 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the concentration of ethylenically unsaturated acid monomers in the monomer mixture is comprised between 30 and 45 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the monofunctional acrylate and/or methacrylate monomer(s) is selected from polymerizable molecules with one ester functionality of the following formula

wherein

R1 = H/CH3,

R2 = -OH, -(CH2)n-OH, O-CH3, -O-(CH2)m-OH, -O-(CH2)n–CH3, -(O-CH2- CH2)n-OH, -(O-CH2-CH2-CH2)n-OH, -(O-CH2-CH2)n-O-CH3, -(O-CH2-CH2)n- O-CH2-CH3, -(O-CH2-CH2-CH2)n-O-CH2-CH3, -(O-CH2-CH2-CH2)n-O-CH3, -(O-CH2-CHR3)n-CH3

n = 1 to 10, m = 2 to 10, and R3 = methyl or ethyl,

or a mixture of two or more of said monomers.

In an embodiment the microcapsule is characterised in that the monofunctional acrylate and/or methacrylate monomer(s) is selected from 2-hydroxyethyl methacrylate, poly(ethylene glycol) methacrylate, Poly(propylene glycol) methacrylate, 4-hydroxybutyl acrylate, hydroxybutyl methacrylate, Hydroxypropyl acrylate, Hydroxypropyl methacrylate 6-hydroxyhexyl acrylate, 6-hydroxyhexyl methacrylate, or a mixture of two or more of said monomers.

In an embodiment the microcapsule is characterised in that the monofunctional acrylate and/or methacrylate monomer(s) is hydroxyethyl methacrylate.

In an embodiment the microcapsule is characterised in that the concentration of the monofunctional acrylate and/or methacrylate monomer(s) is comprised between 5 and 50 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the multifunctional acrylate and/or methacrylate monomer(s) is selected from polymerizable molecules with more than one ester functionalities.

In an embodiment the microcapsule is characterised in that the one or more multifunctional acrylate and/or methacrylate monomer(s) is a mixture of two or more of said monomers,

In an embodiment the microcapsule is characterised in that the multifunctional acrylate and/or methacrylate monomer(s) is selected from ethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,4-Butanediol diacrylate, 1,4-Butanediol dimethacrylate, 1,6-hexane diol dimethacrylate, Glycerol diacrylate, Glycerol dimethacrylate, 1,10-Decanediol dimethacrylate, Bis[2-(methacryloyloxy)ethyl] phosphate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, or a mixture of two or more of said monomers.

In an embodiment the microcapsule is characterised in that the multifunctional acrylate and/or methacrylate monomer(s) is a mixture of two or more of said monomers, each of said monomer representing less than 30 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the total concentration of the multifunctional acrylate and/or methacrylate monomer(s) in the monomer mixture is less than 60 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the concentration of the multifunctional acrylate and/or methacrylate monomer(s) in the monomer mixture is comprised between 20 and 50 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the concentration of vinyl acetate monomer in the monomer mixture is comprised between 0.05 and 15 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the concentration of a) ethylenically unsaturated acid monomer(s), b) monofunctional acrylate and/or methacrylate monomer(s), c) multifunctional acrylate and/or methacrylate monomer(s), and d) vinyl acetate monomer, is at least 95 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the concentration of a) ethylenically unsaturated acid monomer(s), b) monofunctional acrylate and/or methacrylate monomer(s), c) multifunctional acrylate and/or methacrylate monomer(s), and d) vinyl acetate monomer, [a) + b) + c) + d)] is 100 percent by weight based on the total weight of the mixture of monomers.

In an embodiment the microcapsule is characterised in that the Particle Size of the microcapsule ranges from 8 to 35 microns of Dv (90) value.

In an embodiment the microcapsule is characterised in that the lipophilic core material of the microcapsules has a density equal or less than 0.95 g/cm3 at 25 °C with a combined log P comprised between 2.5 and 6.0.

In an embodiment the microcapsule is characterised in that the lipophilic core material of the microcapsules comprises at least 95 percent by weight, preferably 100 percent by weight, based on the total weight of said lipophilic core material, of one or more of the following ingredients: fragrances, profragrances, emollient oils, essential oils, hair-benefitting agents, skin-benefitting agents, conditioner actives, cosmetic care actives, personal care actives, UV absorbers, vitamins, anti-oxidants, anti-microbial agents, anti-viral, flavors, anti-malodor agents, pharmaceutical agents, dyes, printing inks, pesticides, biocides, agrochemicals, coating materials, anti-ageing actives.

In an embodiment the microcapsule is characterised in that the lipophilic core material of the microcapsules comprises one or more of the following ingredients: fragrances, essential oils, hair- benefitting agents, skin-benefitting agents, anti-microbial agents, anti-viral agents, anti-malodor agents.

In an embodiment the microcapsule is characterised in that the lipophilic core material weight divided by the shell weight of the microcapsule is comprised between 15 and 0.2, for example between 15 and 0.33, for example between 15 and 0.4.

Aqueous microcapsule composition comprising water and microcapsules according to claim 1 wherein the water represents from 35 to 82 weight percent of the total weight of the aqueous microcapsule composition.

The present invention also relates to an aqueous microcapsule composition comprising a microcapsule comprising a lipophilic core material and a microcapsule shell wherein said microcapsule shell is formed from oil-in-water emulsion polymerisation of a mixture of monomers, more than 50 percent by weight of the mixture of monomers consisting in monomers having a density higher than 1.05, said mixture of monomers comprising a) more than 30 percent by weight of one or more of ethylenically unsaturated acid monomer(s) based on the total weight of the mixture of monomers, b) one or more monofunctional acrylate and/or methacrylate monomer(s), c) one or more multifunctional acrylate and/or methacrylate monomers, and d) vinyl acetate monomer, and

wherein the lipophilic core material represents between 15 and 45 percent by weight of the total weight of the aqueous microcapsule composition.

In an embodiment, the aqueous microcapsule composition is characterized in that it comprises one or more emulsifiers wherein the emulsifiers represent from 0.05 to 5 weight percent of the total weight of the aqueous microcapsule composition.

In an embodiment, the aqueous microcapsule composition is characterized in that the weight of water, microcapsules and emulsifier represents at least 90% by weight of the total weight of the aqueous microcapsule composition.

The present invention also relates to a process for preparing an aqueous microcapsule composition comprising a microcapsule comprising a lipophilic core material and a microcapsule shell

wherein said microcapsule shell is formed from oil-in-water emulsion polymerisation of a mixture of monomers, more than 50 percent by weight of the mixture of monomers consisting in monomers having a density higher than 1.05, said mixture of monomers comprising a) more than 30 percent by weight of one or more of ethylenically unsaturated acid monomer(s) based on the total weight of the mixture of monomers, b) one or more monofunctional acrylate and/or methacrylate monomer(s), c) one or more multifunctional acrylate and/or methacrylate monomers, and d) vinyl acetate monomer, and

wherein the lipophilic core material represents between 15 and 45 percent by weight of the total weight of the aqueous microcapsule composition,

comprising the steps of:

1. dissolving the mixture of monomers together with an initiator in an oil phase comprising the lipophilic core material and heating the oil phase to form prepolymer(s),

2. dissolving an emulsifier in an aqueous phase,

3. emulsifying the oil phase of step 1 into the aqueous phase of step 2, and

4. heating the emulsion from step 3 to form a suspension of core-shell microcapsules in water.

In an embodiment the process for preparing an aqueous microcapsule composition is characterized in that the emulsification step of the core phase in the water phase is obtained by stirring at 500-1500 rpm for up to 12 minutes using a propeller type stirrer.

The present invention also relates to a non-therapeutic method of use of a microcapsule or an aqueous microcapsule composition as claimed comprising employing said microcapsule to deliver the lipophilic core material for industrial compositions that are related to home care products, personal care products, textile products, printing and coating applications products, pharmaceutical formulations products, consumer goods products, and in agro-industrial formulation products.

In an embodiment, said non-therapeutic method of use is characterized in that the mechanical stress and temperature conditions at which the microcapsule is exposed are sufficient to break the microcapsule shell and to deliver the lipophilic core material.

In an embodiment, said non-therapeutic method of use according to the present invention applies to the steaming of fabric, hair-straightening, paints, textile-processing, and shoe insole making.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The following description relates to particular embodiments pertaining to the present invention.

As discussed hereinbefore, the present invention provides for polymeric shell and lipophilic active-core containing formaldehyde-free microcapsules, with high thermal stability, which breaks above 250 °C, is suitable for applications at high temperatures such as but not limited to in steaming of fabric, hair-straightening, paints, textile-processing, and shoe insole making etc., where the polymeric shell comprising a crosslinked (meth)acrylic-vinyl acetate copolymer.

For the man skilled in the art, a microcapsule comprising a lipophilic core material and a microcapsule shell which is thermally stable at 250°C means that said microcapsule shell does not break at 250°C.

Any appropriate measurement method can advantageously be used for measuring said characteristic of being thermally stable at 250°C.

For example, it may advantageously be measured by taking a sample of the microcapsule slurry intended to be commercialized, e.g. a sample of the microcapsule slurry as obtained at the end of the example 1 hereinbelow; by examining said microcapsule slurry sample using a thermogravimetric analyzer (TGA); by subjecting it to a ramp of increased temperatures, for example from ambient temperature up to 250°C by increments of 30°C per minute; and by measuring the lipophilic core material weight loss. When lipophilic core material weight loss is below 7.5 percent by weight, preferably below 5 percent by weight based on the total weight of the encapsulated core material, it may be concluded that the microcapsule is thermally stable at 250°C.

CLAIMS

SET OF CLAIMS

1. A microcapsule comprising a lipophilic core material and a microcapsule shell wherein said microcapsule shell is formed from oil-in-water emulsion polymerisation of a mixture of monomers, more than 50 percent by weight of the mixture of monomers consisting in monomers having a density higher than 1.05, said mixture of monomers comprising a) more than 30 percent by weight of one or more of ethylenically unsaturated acid monomer(s) based on the total weight of the mixture of monomers, b) one or more monofunctional acrylate and/or methacrylate monomer(s), c) one or more multifunctional acrylate and/or methacrylate monomers, and d) vinyl acetate monomer.

2. A microcapsule according to claim 1 which is thermally stable at 250°C.

3. A microcapsule according to claim 1 which is formaldehyde-free.

4. A microcapsule according to claim 1 wherein the log P values of all the monomers comprised in the mixture of monomers range from 0.5 to 4.0.

5. A microcapsule according to claim 1 wherein the ethylenically unsaturated acid monomer(s) is selected from acrylic acid, methacrylic acid, crotonic acid, 2- carboxyethyl acrylate, glutaconic acid, 3,3-Dimethylacrylic acid, itaconic acid, maleic acid, fumaric acid or a mixture of two or more of said acids.

6. A microcapsule according to claim 1 wherein the ethylenically unsaturated acid monomer is methacrylic acid.

7. A microcapsule according to any one of claims 5 or 6 wherein the concentration of ethylenically unsaturated acid monomers in the monomer mixture is equal or inferior to 45 percent by weight based on the total weight of the mixture of monomers.

8. A microcapsule according to any one of claims 5 or 6 wherein the concentration of ethylenically unsaturated acid monomers in the monomer mixture is comprised between 30 and 45 percent by weight based on the total weight of the mixture of monomers.

9. A microcapsule according to claim 1 wherein the monofunctional acrylate and/or methacrylate monomer(s) is selected from polymerizable molecules with one ester functionality of the following formula

wherein

R1 = H/CH3,

R2 = -OH, -(CH2)n-OH, O-CH3, -O-(CH2)m-OH, -O-(CH2)n–CH3, -(O-CH2- CH2)n-OH, -(O-CH2-CH2-CH2)n-OH, -(O-CH2-CH2)n-O-CH3, -(O-CH2-CH2)n- O-CH2-CH3, -(O-CH2-CH2-CH2)n-O-CH2-CH3, -(O-CH2-CH2-CH2)n-O-CH3, -(O-CH2-CHR3)n-CH3

n = 1 to 10, m = 2 to 10, and R3 = methyl or ethyl,

or a mixture of two or more of said monomers.

10. A microcapsule according to claim 1 wherein the monofunctional acrylate and/or methacrylate monomer(s) is selected from 2-hydroxyethyl methacrylate, poly(ethylene glycol) methacrylate, Poly(propylene glycol) methacrylate, 4-hydroxybutyl acrylate, hydroxybutyl methacrylate, Hydroxypropyl acrylate, Hydroxypropyl methacrylate 6- hydroxyhexyl acrylate, 6-hydroxyhexyl methacrylate, or a mixture of two or more of said monomers.

11. A microcapsule according to claim 1 wherein the monofunctional acrylate and/or methacrylate monomer(s) is hydroxyethyl methacrylate.

12. A microcapsule according to any one of claims 9 to 11 wherein the concentration of the monofunctional acrylate and/or methacrylate monomer(s) is comprised between 5 and 50 percent by weight based on the total weight of the mixture of monomers.

13. A microcapsule according to claim 1 wherein the multifunctional acrylate and/or methacrylate monomer(s) is selected from polymerizable molecules with more than one ester functionalities.

14. A microcapsule according to claim 1 wherein the multifunctional acrylate and/or methacrylate monomer(s) is selected from ethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,4-Butanediol diacrylate, 1,4-Butanediol dimethacrylate, 1,6- hexane diol dimethacrylate, Glycerol diacrylate, Glycerol dimethacrylate, 1,10- Decanediol dimethacrylate, Bis[2-(methacryloyloxy)ethyl] phosphate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, or a mixture of two or more of said monomers.

15. A microcapsule according to claim 14 wherein the multifunctional acrylate and/or methacrylate monomer(s) is a mixture of two or more of said monomers, each of said monomer representing less than 30 percent by weight based on the total weight of the mixture of monomers.

16. A microcapsule according to any one of claims 13 to 15 wherein the total concentration of the multifunctional acrylate and/or methacrylate monomer(s) in the monomer mixture is less than 60 percent by weight based on the total weight of the mixture of monomers.

17. A microcapsule according to any one of claims 13 to 15 wherein the concentration of the multifunctional acrylate and/or methacrylate monomer(s) in the monomer mixture is comprised between 20 and 50 percent by weight based on the total weight of the mixture of monomers.

18. A microcapsule according to claim 1 wherein the concentration of vinyl acetate monomer in the monomer mixture is comprised between 0.05 and 15 percent by weight based on the total weight of the mixture of monomers.

19. A microcapsule according to claim 1 wherein the concentration of a) ethylenically unsaturated acid monomer(s), b) monofunctional acrylate and/or methacrylate monomer(s), c) multifunctional acrylate and/or methacrylate monomer(s), and d) vinyl acetate monomer, is at least 95 percent by weight based on the total weight of the mixture of monomers.

20. A microcapsule according to claim 19 wherein the concentration of [a) + b) + c) + d)] is 100 percent by weight based on the total weight of the mixture of monomers.

21. A microcapsule according to claim 1 wherein the Particle Size of the microcapsule ranges from 8 to 35 microns of Dv (90) value.

22. A microcapsule according to claim 1 wherein the lipophilic core material of the microcapsules has a density equal or less than 0.95 g/cm3 at 25 °C with a combined log P comprised between 2.5 and 6.0.

23. A microcapsule according to claim 1 wherein the lipophilic core material of the microcapsules comprises at least 95 percent by weight based on the total weight of said lipophilic core material, of one or more of the following ingredients: fragrances, profragrances, emollient oils, essential oils, hair-benefitting agents, skin-benefitting agents, conditioner actives, cosmetic care actives, personal care actives, UV absorbers, vitamins, anti-oxidants, anti-microbial agents, anti-viral, flavors, anti-malodor agents, pharmaceutical agents, dyes, printing inks, pesticides, biocides, agrochemicals, coating materials, anti-ageing actives.

24. A microcapsule according to claim 23 wherein the lipophilic core material of the microcapsules comprises one or more of the following ingredients: fragrances, essential oils, hair- benefitting agents, skin-benefitting agents, anti-microbial agents, anti-viral agents, anti-malodor agents.

25. A microcapsule according to claim 1 wherein the lipophilic core material weight divided by the shell weight of the microcapsule is comprised between 15 and 0.33.

26. Aqueous microcapsule composition comprising water and microcapsules according to claim 1 wherein the water represents from 35 to 82 weight percent of the total weight of the aqueous microcapsule composition.

27. Aqueous microcapsule composition according to claim 26 wherein the lipophilic core material represents between 15 and 45 percent by weight of the total weight of the aqueous microcapsule composition.

28. Aqueous microcapsule composition according to claim 26 comprising one or more emulsifiers wherein the emulsifiers represent from 0.05 to 5 weight percent of the total weight of the aqueous microcapsule composition.

29. Aqueous microcapsule composition according to claim 28 wherein the weight of water, microcapsules and emulsifier represents at least 90% by weight of the total weight of the aqueous microcapsule composition.

30. A process for preparing an aqueous microcapsule composition as claimed in any one of claims 26 to 29 comprising the steps of:

5. dissolving the mixture of monomers together with an initiator in an oil phase comprising the lipophilic core material and heating the oil phase to form prepolymer(s),

6. dissolving an emulsifier in an aqueous phase,

7. emulsifying the oil phase of step 1 into the aqueous phase of step 2, and

8. heating the emulsion from step 3 to form a suspension of core-shell microcapsules in water.

31. A process according to claim 30 wherein the emulsification step of the core phase in the water phase is obtained by stirring at 500-1500 rpm for up to 12 minutes using a propeller type stirrer.

32. A non-therapeutic method of use of a microcapsule according to any one of claims 1 to 25 or an aqueous microcapsule composition according to any one of claims 26 to 29 comprising employing said microcapsule to deliver the lipophilic core material for industrial compositions that are related to home care products, personal care products, textile products, printing and coating applications products, pharmaceutical formulations products, consumer goods products, and in agro-industrial formulation products.

33. Non-therapeutic method of use according to the preceding claim wherein the mechanical stress and temperature conditions at which the microcapsule is exposed are sufficient to break the microcapsule shell and to deliver the lipophilic core material.

34. Non-therapeutic method of use according to the preceding claim for the steaming of fabric, hair-straightening, paints, textile-processing, and shoe insole making.