NANO-PARTICULATE CAPSULES AND EMULSIONS THEREOF INCLUDING FRAGRANCE BY EMULSION POLYMERIZATION

Abstract

A nano-particulate composition comprising nano-particulate capsule comprising at least one or more of hydrophobic core material and a polymeric shell comprising homo-polymer or copolymers of at least one ethylenically unsaturated monomers or mixture thereof and having particle size distribution with an average article size in the range of 50 to 1000 nm is provided together with a controlled release delivery system comprising fragrance release delivery system involving said nano-particulate capsule water based emulsion and a process of manufacture thereof. Said delivery system provided is able to protect and release the fragrance in a controlled manner over a period of time. The controlled release fragrance delivery system of the present invention finds advantageous end use and application in fragranced consumer products formulations including water based coating/paint formulations and industrial formulations for use in industries including textile, cosmetics, soaps and detergents, leather industries.

Claims

1. Nano-particulate capsule comprising at least one or more of hydrophobic core material and a polymeric shell comprising homo-polymer or copolymers of at least one ethylenically unsaturated monomers or mixture thereof and having particle size distribution with an average particle size in the range of 50 to 1000 nm.

2. Nano-particulate capsule according to claim 1 wherein said hydrophobic core material and said shell material are selected to facilitate said nano-capsule formation involving hydrophobic core material in solution with polymeric shell forming material without being reactive to each other.

3. Nano-particulate capsule according to claim 1 comprising controlled fragrance releasing nano-particulate capsule wherein said hydrobhobic core material comprises hydrophobic fragrance material and said shell material facilitating controlled release of said fragrance material.

4. Nano-particulate capsule according to claim 1 wherein said shell material is selected depending upon the desired cross-link density and thickness of the shell material based on the desired control release of hydrophobic core material content.

5. Nano-particulate capsule water based emulsion comprising nano-particulate capsule having core material of at least one or more hydrophobic fragrance and a polymeric shell comprising homopolymer or copolymers of at least one ethylenically unsaturated monomers or mixture thereof and having particle size distribution with an average article size in the range of 50 to 1000 nm.

6. Nano-particulate capsule water based emulsion according to claim 5 wherein said nano-particulate capsule comprise water based emulsion polymerized monomers around surface of said core material containing fragrance droplet.

7. Nano-particulate capsule water based emulsion according to claim 5 comprising a controlled release fragrance delivery system.

8. Nano-particulate capsule water based emulsion according to claim 5 having stormer viscosity in the range of 40 to 120 g preferably to 80 g.

9. Nano-particulate capsule water based emulsion according to claim 5 wherein said polymeric shell involves a polymer composition comprising at least one ethylenically unsaturated monomer or mixture of ethylenically unsaturated monomers in the range of 5 to 50 wt %, preferably 10 to 35 wt %; and said core material comprise fragrance droplet of at least one hydrophobic fragrance inside said. polymeric shell in the range of 1 to 40 wt. %, more preferably 5 to 30 wt %. that is liquid at 25° C. which emanates a pleasant or otherwise desirable odour.

10. Nano-particulate capsule water based emulsion according to claim 5 comprising (i) at least one ethylenically unsaturated monomer or mixtures thereof in the range of 5 to 50 wt. %, preferably 10 to 35 wt. %; (ii) at least one fragrance that is liquid at 25° C. in range of 1 to 40 wt %, preferably 5 to 30 wt. %; (iii) at least one anionic or non-ionic surface active agents (or surfactants) or mixtures thereof in the range of 0.5 to 10 wt. %, preferably 1 to 5 wt. %; (iv) at least one water soluble initiator or mixtures thereof in the range of 0.1 to 3 wt. %, preferably in the range of 0.3 to 1.5 wt. %; and includes semi-continuous/seeded emulsion polymerised monomers around the surface of the fragrance droplet as said nano-capsules as template polymers with enhanced retention and reduced diffusion of fragrance molecules through the polymeric shell.

11. Nano-particulate capsule water based emulsion according to claim 5 wherein said fragrance are odoriferous materials of relatively low boiling point, of less than 3000 C are liquid at room temperatures and are more soluble in organic phase than aqueous phase selected from chemicals including aldehydes, ketones, esters, alcohols, terpenes and the like also including naturally occurring plant and animal oils and extrudates comprising complex mixtures of various chemical components including woody/earthy bases containing exotic materials such as sandalwood oil, civet, patchouli oil, light floral fragrances including rose extract, Jasmine extract, violet extract also involving fruity odours of lime, lemon, orange and the like.

12. Nano-particulate capsule water based emulsion according to claim 5 wherein said monomers are selected from the group consisting of olefins, ethylene, vinylaromatic monomers, esters of vinyl alcohol with mono- and di-carboxylic acids, esters of α, β-monoethylenically unsaturated mono- and dicarboxylic acids with alcohols, α, β-monoethylenically unsaturated monocarboxylic and dicarboxylic acids and their amides, methacrylic acid and its esters with alcohols and diols, acrylic acid and its esters with alcohols and diols or mixtures thereof and are preferably selected from: styrene; α-methylstyrene; o-chlorostyrene; vinyl acetate; vinyl propionate; vinyl n-butyrate; esters of acrylic, methacrylic acid with methyl, ethyl, n-butyl, isobutyl, n-hexyl and 2-ethylhexyl alcohol and preferable monomers are styrene, methylmethacrylate and methacrylic acid.

13. Nano-particulate capsule water based emulsion according to claim 12 wherein said monomers may optionally comprise monomers which are cross-linkers having at least two non-conjugated ethylenically unsaturated double bonds including alkylene glycol diacrylates and dimethacrylates, conjugated double bonds such as divinyl benzene from 0.1 to 10% by weight, based on the total amount of monomers to be polymerised.

14. Nano-particulate capsule water based emulsion according to claim 5 comprising non-ionic emulsifiers, including ethoxylated linear fatty alcohols, of C12-C14 fatty alcohols ethoxylated with ethylene oxide, ethylene oxide/propylene oxide block copolymers, selected from sorbitan stearate, polysorbate, and stearate, or mixtures thereof.

15. Nano-particulate capsule water based emulsion according to claim 5 comprising anionic emulsifiers including disulfonated surfactant with tetrapropylene hydrophobe source, sodium dodecyl sulfate, ammoniumnonoxynol-sulfate, glyceryl stearate, or mixtures thereof.

16. Nano-particulate capsule water based emulsion according to claim 5 comprising initiators for emulsion polymerization that are water soluble initiators like peroxodisulfates, organic peroxides, hydroperoxides and water soluble azo-compounds selected from ammonium persulfate, sodium persulfate, potassium persulfate, 1,4-diisopropylbenzene hydroperoxide, cumene hydroperoxide, 2,2′-azobis(2-methylpropio-namidine)dihydrochlorid and 4,4′-azobis(4-cyanovaleric acid) preferably ammonium, potassium or sodium persulfates which allow thermic initiations.

17. A process for the preparation of nano-particulate capsule water based emulsion of claim 5 comprising the steps of (a) providing a solution of monomer of shell material in a liquid hydrophobic core material; (b) dispersing the solution of step (a) into an emulsified aqueous phase under stirring to form pre-emulsion; (c) subjecting a selective amount of pre-emulsion to controlled polymerization in emulsified aqueous phase for generating in-situ seeds followed by adding the remaining pre-emulsion facilitating polymerization of said monomers around the surface of droplets of said liquid core material content.

18. A process according to claim 17 wherein said hydrophobic core material and said shell material are selected to facilitate said nano-capsule formation involving hydrophobic core material in solution with polymeric shell forming material without being reactive to each other.

19. A process for the preparation of nano-particulate capsule water based emulsion according to claim 17 wherein said step (c) of involves subjecting the pre-emulsion in the range of 1 to 25 wt. %, preferably in the range of 2 to 10 wt. % to controlled polymerization for generating in-situ seeds followed by addition of remaining pre-emulsion.

20. A process according to claim 17 wherein said step (c) for in-situ seed generation takes place in the temperature range of 50 to 90° C., preferably in the range of 65 to 85° C. under stirring followed by the addition of remaining pre-emulsion through peristaltic pump for polymerization in the temperature range of 60 to 90° C., preferably in the range of 65 to 85° C. over a period of 1 to 6 hours, preferably 2 to 5 hours.

21. A process according to claim 17 wherein said step (a) involves providing (i) at least one ethylenically unsaturated monomer or mixtures thereof in the range of 5 to 50 wt. %, preferably 10 to 35 wt. %; (ii) at least one hydrophobic core material including fragrance that is liquid at 25° C. in the range of 1 to 40 wt %, preferably 5 to 30 wt. %. said step (b) involves dispersing the solution of step (a) in (iii) at least one anionic or non-ionic surface active agents (or surfactants) or mixtures thereof taken in the range of 0.5 to 10 wt. %, preferably 1 to 5 wt. %; (iv) at least one water soluble initiator or mixtures thereof in the range of 0.1 to 3 wt. %, preferably in the range of 0.3 to 1.5 wt. %.

22. Consumer product formulations including water based coating/paint formulations and industrial formulations comprising nano-particulate capsule water based emulsion at levels of from 0.001% to 10%, preferably from 0.1% to 5% by weight of the total formulation having core material of at least one or more hydrophobic fragrance and a polymeric shell comprising homo-polymer or copolymers of at least one ethylenically unsaturated monomers or mixture thereof miscible but unreactive with said core fragrance material favouring nano-particulate capsules with uniform core shell morphology and narrow particle size distribution with an average article size in the range of 50 to 1000 nm.

23. Consumer product formulations according to claim 22 comprising controlled fragrance releasing nano-particulate capsule based formulations wherein said hydrobhobic core material comprises hydrophobic fragrance material and said material facilitating controlled release of said fragrance material under ambient conditions.

24. Nano-particulate capsule according claim 1 comprising in-situ polymerizaton encapsulating said hydrophobic core material in said polymeric shell.

25. Nano-particulate capsule water based emulsion according to claim 5 comprising in-situ polymerization enapsulating said hydrophobic core material in said polymeric shell.

Description

BRIEF DESCRIPTION OF FIGURES

[0071] FIG. 1. SEM images of Jasmine encapsulated polymer capsules (a)-original and (b)-measured.

DETAILED DESCRIPTION OF THE INVENTION

[0072] As discussed hereinbefore the present invention provides for nano-particulate capsule comprising at least one or more of hydrophobic core material and a polymeric shell comprising homo-polymer or copolymers of at least one ethylenically unsaturated monomers or mixture thereof and having particle size distribution with an average article size in the range of 50 to 1000 nm. A controlled release delivery system comprising a controlled fragrance release delivery system is provided comprising said nano-particulate capsule water based emulsion with a process of manufacture of said emulsion. Said delivery system is able to protect and release the fragrance in a controlled manner over a period of time. The controlled release fragrance delivery system of the present invention finds advantageous end use and application in fragranced consumer products formulations including water based coating/paint formulations and industrial formulations for use in industries including textile, cosmetics, soaps and detergents, leather industries.

[0073] In order to the present invention, further it is described in detail below with reference to preferred features.

[0074] The nano-capsules of the present invention comprise a core containing a hydrophobic fragrance liquid and a polymeric shell where the hydrophobic fragrances are liquids at 25° C. and are mixtures of many components.

[0075] Fragrances can be classified according to their volatility. The highly volatile, low boiling, fragrance ingredients typically have boiling points of about 2500 C or lower. The moderately volatile fragrance ingredients are those having boiling point of about 250-3000 C. The less volatile, high boiling, fragrance ingredients are those having boiling points of about 3000 C or higher. It is advantageous to encapsulate, those with a relatively low boiling point, preferably those with a boiling point of less than 3000 C.

[0076] Fragrances are typically composed of many components of different volatility. The present invention, avoiding separation of the components based on their different volatility, allows the sustained delivery of the full fragrance bouquet for a long time.

[0077] As used herein the term fragrance means any odoriferous material. In general, such materials are characterised by a vapour pressure less than atmospheric pressure at room temperature. The fragrances employed herein will most often be liquid at room temperatures and are more soluble in organic phase than aqueous phase. A wide variety of chemicals are used as fragrances, including materials such as aldehydes, ketones, esters, alcohols, terpenes and the like. Naturally occurring plant and animal oils and extrudates comprising complex mixtures of various chemical components are known for use as fragrances, and such materials can be used herein.

[0078] The fragrances herein can be relatively simple in their composition or can comprise highly sophisticated, complex mixtures of natural and synthetic chemical components, all chosen to provide any desired odour.

[0079] Typical fragrances which can be used in the present invention comprise, for example, woody/earthy bases containing exotic materials such as sandalwood oil, civet, patchouli oil and the like. Other suitable fragrances are for example light, floral fragrances, e.g., rose extract, Jasmine extract, violet extract and the like. Fragrances can be formulated to provide desirable fruity odours, e.g., lime, lemon, orange and the like.

[0080] In short, any chemically compatible material which emanates a pleasant or otherwise desirable odour can be used as a fragrance in the present invention.

[0081] The amount of the active ingredient suitable for encapsulation mainly depends on the desirable effect of the end product. For example, if the active ingredient is a fragrance, an amount up to 20% by weight, based on the emulsion, is suitable.

[0082] The polymer particles of .the invention can comprise a wide selection of monomeric units. By monomer units as used herein is meant the monomeric units of the polymer chain.

[0083] Monomers for free radical polymerization:

[0084] Suitable classes of such monomers are given in the group consisting of olefins, ethylene, vinylaromatic monomers, esters of vinyl alcohol with mono- and di-carboxylic acids, esters of α, β-monoethylenically unsaturated mono- and dicarboxylic acids with alcohols, α, β-monoethylenically unsaturated monocarboxylic and dicarboxylic acids and their amides, methacrylic acid and its esters with alcohols and diols, acrylic acid and its esters with alcohols and diols. The polymer particle may comprise mixtures of monomer units.

[0085] The monomers are preferably selected from: styrene; α-methylstyrene; o-chlorostyrene; vinyl acetate; vinyl propionate; vinyl n-butyrate; esters of acrylic, methacrylic acid with methyl, ethyl, n-butyl, isobutyl, n-hexyl and 2-ethylhexyl alcohol. The preferred monomers are styrene, methylmethacrylate and methacrylic acid.

[0086] The polymer particle may optionally comprise monomers which are cross-linkers. Such cross-linkers may have at least two non-conjugated ethylenically unsaturated double bonds. Examples are alkylene glycol diacrylates and dimethacrylates. Further types of suitable cross-linking monomers are those that are conjugated, such as divinyl benzene. If present, these monomers constitute from 0.1 to 10% by weight, based on the total amount of monomers to be polymerised.

[0087] Optional cross-linkers include vinyltoluenes, divinyl benzene, ethylene glycol diacrylate, 1,2-propylene glycol diacrylate, 1,3-propylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylates, ethylene glycol dimethacrylate, 1,2-propylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate.

[0088] The choice of a suitable emulsifier is less critical in the polymerization process of the present invention. Anionic, cationic and non-ionic emulsifiers are suitable, however anionic and non-ionic emulsifiers are preferred.

[0089] The following list comprises examples of emulsifiers suitable for the preparation of polymer particles according to the present invention:

[0090] Non-ionic emulsifiers, e.g. ethoxylated linear fatty alcohols, such as C12-C14 fatty alcohols ethoxylated with ethylene oxide, ethylene oxide/propylene oxide block copolymers, e.g. available from Uniqema under the trade name Synperonic™, sorbitan stearate, polysorbate, and stearate, or mixtures thereof, e.g. available from Croda under the trade name of Tween.

[0091] Anionic emulsifiers, e.g. disulfonated surfactant with tetrapropylene hydrophobe source available from DOW under the trade name of Dowfax 2A1, odium dodecyl sulfate, ammoniunnnonoxynol-sulfate, e.g. available from Rhodia under the trade name Abex EP-227, and glyceryl stearate, or mixtures thereof.

[0092] Initiators useful for emulsion polymerization are watersoluble initiators like peroxodisulfates, organic peroxides, hydroperoxides and water soluble azo-compounds. Specific examples of suitable initiators are ammonium persulfate, sodium persulfate, potassium persulfate, 1,4-diisopropylbenzene hydroperoxide, cumene hydroperoxide, 2,2′-azobis(2-methylpropionamidine)dihydrochlorid and 4,4′-azobis(4-cyanovaleric acid).

[0093] Preferred are the ammonium, potassium or sodium persulfates which allow thermic initiations.

[0094] In general, the polymerization is performed by admixing the monomer, the active ingredient, emulsifier and water at room temperature or elevated temperature to obtain an emulsion, followed by initiation of the polymerization reaction by addition of initiator catalyst. The polymerization reaction is preferably performed under elevated temperature up to about 900 C or lower. Depending on the reactivity of the monomer and the catalyst, it may take between a few hours, e.g. two to five hours, up to several days until the polymerization reaction is completed. Whether the polymerization process is completed or not may be analysed by measuring the monomer concentration by methods known to the persons skilled in the art. The polymerization reaction is completed when the monomer concentration of the aqueous phase is stable over a longer period.

[0095] Accordingly, the present invention relates in a further aspect to a method of preparing polymer particles comprising the steps of 1) forming a solution of monomer in a fragrance liquid, 2) dispersing the monomer solution into an aqueous phase under stirring to form an emulsion, 3) subjecting the emulsion, 1 to 25 wt %, to polymerization for generating in-situ seeds followed by addition of remaining emulsion using peristaltic pump over a period of 2-5 hours at temperature range between 60 to 90° C. Under these conditions the core shell particles formation assumed to be the formation of polymer around the fragrance molecules.

[0096] The final latex particle size in emulsion polymerization is controlled by the short nucleation stage at the start of the reaction and by the stabilisation of nuclei during the growth stage. Nucleation depends on the formation of radicals, a process that is very variable. This variability leads to variations in polymerization rate and in the size of the final latex particle. The addition of seed particles at the start of the reaction, removes the variability in the nucleation step. Polymerisation rate and particle size can be easily controlled. Seeded emulsion polymerization also give less reactor build up, reduced pebble and give more stable latices.

[0097] The polymer particles of the invention may be incorporated in paint or coating compositions. This may be done by mixing the capsules dispersion with some or all of the other components of the paint or coating composition. The nano-capsule dispersions are typically included in said compositions at levels of from 0.001% to 10%, preferably from 0.005% to 5% by weight of the total composition.

EXAMPLES

Example 1

Pre-Emulsion Preparation

[0098] An oil phase was prepared by mixing 80 g of Rose Breeze with 120 g of methylmethacrylate. An aqueous phase was prepared by mixing 233g of demineralised water, 6.75 g of Tween 20, 2.25 g of Dow Fax and 0.5 g of sodium bicarbonate. The prepared oil phase was slowly added to aqueous phase under stirring with anchor stirrer at room temperature for about 15 minutes. To get stable oil in water emulsion, stirring continued for about 30 minutes.

[0099] In-Situ Seed Generation and Polymerisation

[0100] A 1 liter reaction flask equipped with a stirrer, reflux condenser, thermometer and inlet tube for delivery from a peristaltic pump is placed in a water batch. The seed materials 55 g of demineralised water, 0.75 g of Tween 20, and 0.25 g of Dow fax were charged in to the reaction flask and then the content of the reaction flask was heated to 80° C. At this temperature 0.2 g of potassium persulfate and 5% of the above prepared pre-emulsion was charged and allowed to polymerise. After 10 minutes the remaining pre-emulsion was added dropwise in to the reaction flask under stirring at 150 rpm, using a peristaltic pump over a period of 180 minutes. After terminating the addition, the reaction mixture is stirred for further 60 more minutes before the reaction mixture is cooled to room temperature. The resulting nano-capsules had a solid content of 40% and an average particle size of 150 nm.

Example 2

[0101] Example 1 was repeated with an oil phase of 120 g of methylmethacrylate and 80 g of Jasmine oil. In example 1 the Tween 20 was replaced with Tween 80. The prepared nano-capsules dispersion had a solid content of 40% and average particle size of 175 nm.

Example 3

[0102] Example 1 was repeated with an oil phase of 29 g of methylmethacrylate, 8 g of methacrylic acid, 85 g of styrene, 1.25 g of ethyleneglycol dimethacrylate and 80 g of Jasmine mist oil. In example 1 the Tween 20 was replaced with Tween 80. The prepared nano-capsules dispersion had a solid content of 40% and average particle size of 132 nm.

[0103] The nano-particulate capsules water based dispersions thus obtained when added to consumer product formulations including water based coating/paint formulations and industrial formulations at levels of from 0.001% to 10%, more preferably only from 0.1% to 5% by weight of the total composition releases fragrance over a period of at least 6 months times under room temperature and pressure conditions whereas under identical conditions if fragrance is directly added (without encapsulation) to paint or coating its release period is only 7 days. Nano-particulate capsule based paints of the present invention when coated in the interior of rooms and continued exude fragrance for at least 6 months.

[0104] It is thus possible by way of the present advancement to provide for nano-particulate capsule and its water based emulsion thereof comprising at least one or more of hydrophobic core material and a polymeric shell comprising homo-polymer or copolymers of at least one ethylenically unsaturated monomers or mixture thereof and having particle size distribution with an average article size in the range of 50 to 1000 nm. Advantageously a controlled release delivery system including fragrance release delivery system comprising said nano-particulate capsule water based emulsion is also provided wherein the core material involves a hydrophobic fragrance material together with a process of manufacture said emulsion. Said delivery system is able to protect and release the fragrance in a controlled and sustained manner over a period of time. The controlled release fragrance delivery system of the present invention advantageously finds end use and application in fragranced consumer products formulations including water based coating/paint formulations and industrial formulations for use in industries including textile, cosmetics, soaps and detergents, leather industries.