EP4251314A1 - Method for producing fragrance microcapsules - Google Patents

Method for producing fragrance microcapsules

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Publication number
EP4251314A1
EP4251314A1 EP21810048.5A EP21810048A EP4251314A1 EP 4251314 A1 EP4251314 A1 EP 4251314A1 EP 21810048 A EP21810048 A EP 21810048A EP 4251314 A1 EP4251314 A1 EP 4251314A1
Authority
EP
European Patent Office
Prior art keywords
chitosan
perfume
microcapsules
heating
polyisocyanate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21810048.5A
Other languages
German (de)
French (fr)
Inventor
Xuan WU
Antoine GOUTEYRON
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jafer Enterprises R&D SL
Original Assignee
Jafer Enterprises R&D SL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jafer Enterprises R&D SL filed Critical Jafer Enterprises R&D SL
Publication of EP4251314A1 publication Critical patent/EP4251314A1/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • B01J13/06—Making microcapsules or microballoons by phase separation
    • B01J13/14—Polymerisation; cross-linking
    • B01J13/16—Interfacial polymerisation
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
    • C11D3/50—Perfumes
    • C11D3/502—Protected perfumes
    • C11D3/505—Protected perfumes encapsulated or adsorbed on a carrier, e.g. zeolite or clay

Definitions

  • the present invention relates to a process for the preparation of perfume microcapsules, which can be used as such or in aqueous suspension as a perfume additive in a detergent, cosmetic or pharmaceutical composition or in textile materials, paper or cardboard.
  • perfumes made up in particular of essential oils, makes it possible to protect them, to avoid the loss of aromatic volatile ingredients, to control the release profile of the perfume and to improve its stability ( I.T. Carvalho et al., International Journal of Cosmetic Science, 2015, 1-11). It is thus possible to formulate these perfumes in different compositions, in particular detergents (WO 2015/104469). Most commonly, encapsulation is done through the copolymerization of aldehyde and polyamine-based compounds.
  • aminoplast resins obtained by polycondensation of a polyamine generally melamine, which is a derivative of triazine
  • an aldehyde most of the time formaldehyde
  • WO 2019/063515 describes perfume microcapsules whose wall is made of polyurea/polyurethane formed by reaction of a polyisocyanate with at least one polyamine including chitosan, derived for example from Aspergillus niger.
  • the chitosan used in this document is preferably non-protonated and used in powder form.
  • the microcapsules are prepared by a process comprising the formation of an oil-in-water emulsion from an aqueous phase at basic pH and an oily phase containing a perfume and a polyisocyanate, then the formation of the shell by adding the polyamine, at a temperature of at least 50°C.
  • WO 2019/179939 discloses perfume microcapsules whose wall is formed by reacting a polyisocyanate with a modified starch and chitosan.
  • the microcapsules are prepared by a process comprising the formation of an oil-in-water emulsion from an aqueous phase at acidic or basic pH, and an oily phase containing a perfume and a polyisocyanate, then the formation of the shell by adding the modified starch and the chitosan in an acid medium, at a temperature of at least 50°C.
  • perfume microcapsules which are used as a perfume additive in detergents, detergents or cosmetic products, however have a moderate olfactory intensity. It would therefore be advantageous to be able to have perfume microcapsules having an improved olfactory intensity.
  • perfume microcapsules comprising a polyurethane-based bark exhibited improved olfactory intensity when the formation of the bark was carried out at a lower temperature than in the methods of the prior art. .
  • This result is all the more surprising since the application of a lower temperature usually allows less crosslinking and therefore a bark that offers less protection of the encapsulated perfume, so that the perfume tends to diffuse slowly out of the bark throughout the storage of the microcapsules, thereby reducing the amount of fragrance available when using the microcapsules and therefore the olfactory intensity of the fragrance.
  • the Applicant has also shown that the olfactory intensity of the perfume was further improved when the method is implemented at a pH greater than or equal to 6, preferably basic.
  • Example 21 thus discloses a process for manufacturing perfume microcapsules by mixing an acidic aqueous phase, containing chitosan, with an oily phase containing a perfume, an organic solvent and an isocyanate-type crosslinking agent, to form a emulsion whose pH is then adjusted to a basic value before heating the emulsion to 30° C. to initiate the polymerization.
  • This process is however complex, insofar as it requires acidification, then neutralization, of the reaction medium.
  • the present invention aims to provide an economically more advantageous process for forming perfume microcapsules having good stability and satisfactory olfactory intensity.
  • the subject of the invention is therefore a method for preparing perfume microcapsules comprising:
  • step (b) heating the emulsion obtained in step (a) in the presence of chitosan at a temperature above 20°C and below 40°C, to form a polyurethane-based shell around an oily core comprising said at least one perfume, and
  • the chitosan being added before, during and/or after the formation of the emulsion in step (a), and before the heating step (b), characterized in that the chitosan is used in the form organic or inorganic acid salt.
  • the present invention relates to a process for preparing microcapsules comprising a polyurethane-based shell and an oily core comprising at least one perfume.
  • the process of the invention is based on two key steps, namely:
  • the oil-in-water emulsion is formed from an aqueous phase, with which is mixed an oily phase comprising at least one perfume and at least one crosslinking agent of polyisocyanate type (step (a)).
  • the aqueous phase of step (a) typically comprises water, and optionally one or more additives chosen from emulsifiers, anti-coalescents, surfactants, stabilizers and mixtures thereof.
  • the aqueous phase advantageously comprises at least one stabilizer, that is to say a hydrophilic polymeric gelling agent capable of maintaining the microcapsules in suspension in the aqueous phase at the end of the process.
  • the aqueous phase comprising a stabilizer can typically be a dispersion formed by mixing water and the stabilizer with stirring.
  • the stabilizer can be used pure, diluted in solution, or in suspension.
  • the mass concentration of stabilizer in the aqueous phase can be between 0.1% and 5%, preferably between 0.3% and 3%, better still between 1 and 1.5%.
  • the stabilizer is chosen from polysaccharides and in particular cellulose, a cellulose derivative such as hydroxypropyl cellulose or hydroxypropyl methyl cellulose, optionally modified starches, or vegetable gums ; polyarginines, lecithins, lactates, sorbates, fatty ester isosorbates; synthetic polymers such as polyvinylpyrrolidone, poly(ethylene oxide), poly(propylene oxide), polyvinyl alcohol, poly(styrene sulfonate), (meth)acrylic polymers such as polyacrylic acid and its salts or polyacrylamidomethylpropane sulfonic acid (AMPS) and its salts, and a mixture thereof. It is preferred that the stabilizer be a polyvinyl alcohol.
  • the oily phase comprises at least one perfume and at least one crosslinking agent of the polyisocyanate type.
  • perfume is meant a single compound or a mixture of volatile and odoriferous compounds. These compounds have a vapor pressure above atmospheric pressure at room temperature. They are notably listed in Merck Index, 8th Edition, Merck & Co., Inc. Rahway, NJ These compounds can be of synthetic or natural origin. It may for example be one or more essential oils of plants, chosen for example from Asteraceae, Myrtaceae, Lauraceae, Lamiaceae, Rutaceae and Zingiberaceae, which are usually extracted from any part of these plants by extraction using a supercritical fluid, hydrodistillation, enfleurage, steam distillation or any other process allowing the extraction of fragrant molecules from a plant. Whether they are of synthetic or natural origin, perfumes generally comprise compounds, possibly terpenes, chosen from alcohols, aldehydes and esters.
  • perfuming compounds can in particular be used as perfume in the present invention, alone or in combination: methyl 2-methyl butyrate; isopropyl 2-methyl butyrate; ethyl 2-methyl butyrate; ethyl 2-methyl pentanoate; ethyl heptanoate; ethyl octanoate; isobutyl hexanoate; amyl butyrate; amyl heptanoate; isoamyl isobutyrate; hexyl acetate; hexyl butyrate; hexyl isobutyrate; hexyl isovalerate; hexyl propionate; ethyl 2-cyclohexyl propanoate; ethyl 3,5,5-trimethyl hexanoate; glyceryl 5-hydroxydecanoate; prenyl acetate; methyl 2-butenyl acetate; methyl 3-nonenoate;
  • crosslinking agent is meant a polyfunctional compound capable of reacting with chitosan.
  • the crosslinking agent is a polyisocyanate, that is to say a compound comprising at least two isocyanate functions (-NCO).
  • the polyisocyanate may in particular comprise at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 50, 100 or 250 isocyanate functions.
  • the polyisocyanate comprises from 2 to 5 isocyanate functions.
  • the polyisocyanate may also comprise other functions, in particular functions derived from the isocyanate function, such as the biuret function, isocyanurate, uretdione, iminooxadiazinedione, trimethylol propane, or more generally, functions resulting from the reaction of an isocyanate with an alcohol or polyol, an amine or polyamine, or a thiol or polythiol.
  • the polyisocyanate can have a monomeric or polymeric structure.
  • the polyisocyanate can in particular be an aliphatic polyisocyanate.
  • aliphatic is meant a hydrocarbon chain, cyclic or acyclic, linear or branched, optionally having one or more carbon-carbon double or triple bonds.
  • the aliphatic polyisocyanate preferably has from 3 to 26 carbon atoms (carbon of the NCO functions included).
  • aliphatic polyisocyanate examples include pentamethylene diisocyanate (PDI), PDI trimer, hexam ethylene diisocyanate (HDI), 1,5-diisocyanato-2-methylpentane, 1,4-diisocyanato-2,3- dimethylbutane, 2-ethyl-1,4- diisocyanatobutane, 1,4-diisocyanatobutane, 1,3-diisocyanatopropane, 1,10- diisocyanatodecane, 1,2- diisocyanatocyclobutane, lysine ethyl ester triisocyanate, isophorone diisocyanate ( IPDI), l,3-bis(isocyanatomethyl)cyclohexane (H6XDI), 1,2-bis(isocyanatomethyl)cyclohexane, l,4-bis(isocyanato-methyl)cyclohexane,
  • the polyisocyanate can alternatively be an aromatic polyisocyanate.
  • aromatic polyisocyanate means a polyisocyanate whose isocyanate functions are directly linked to an aryl (in particular a phenyl).
  • the aromatic polyisocyanate preferably has 6 to 26 carbon atoms (carbon of the NCO functions included).
  • aromatic polyisocyanate examples include diphenylmethylene 2,2'-diisocyanate (2,2'-MDI), diphenylmethylene 4,4'-diisocyanate (4,4'-MDI), 4,4'-dibenzyl diisocyanate ( 4,4'-DBDI), toluene 2,6-diisocyanate (2,6-TDI), m-xylylene diisocyanate (m-XDI), diphenylmethylene 2,4'-diisocyanate (2,4'-MDI), 2,4'-dibenzyl diisocyanate (2,4'-DBDI), toluene 2,4-diisocyanate (2,4-TDI) or methylidyne tri-p-phenylene triisocyanate.
  • Preferred aromatic polyisocyanates are toluene 2,6-diisocyanate (2,6-TDI) or toluene 2,4-diisocyanate (2,4-TDI).
  • Other particular polyisocyanates are in particular tris-N-hexamethylene isocyanate-isocyanurate, biuret from hexamethylene diisocyanate, or trimethylol propane from xylylene diisocyanate.
  • Examples of commercial polyisocyanates are in particular the products Desmodur ® L75, Desmodur ® Eco 7300, or Bayhydur ® Eco 701-90 from Covestro, Takenate ® 600, Stabio ® D-370N or D-376N from Mitsui Chemicals Inc, preferably Desmodur ® Eco 7300 or Bayhydur® Eco 701-90.
  • said at least one polyisocyanate crosslinking agent is selected from PDI, a PDI trimer, and a mixture thereof.
  • the oily phase may consist exclusively of the perfume (that is to say of one or more perfuming compounds), and of the crosslinking agent. Alternatively, it may include any one or more volatile and/or non-volatile oils, of vegetable and/or synthetic origin, in addition to the perfume and the crosslinking agent.
  • the term "oil” is understood to mean a compound which is liquid at ambient temperature (25° C.) and atmospheric pressure (10 5 Pa) which, when it is introduced at a rate of at least 1% by weight into water at 25° C., is not at all soluble in water, or soluble to the extent of less than 10% by weight, relative to the weight of oil introduced into the water.
  • oils can in particular be used to increase the hydrophobic character of the oily phase when the perfume and/or the crosslinking agent are not sufficiently hydrophobic.
  • volatile oils are branched alkanes, such as isododecane, and linear C10-C13 alkanes.
  • hydrocarbon oils As non-volatile oils, mention may be made in particular of hydrocarbon oils and more particularly:
  • esters of acids and of mono-alcohol chosen from: mono- and polyesters of saturated linear C2-C10 acids (preferably C6-C10) and of saturated linear C10-C18 mono-alcohols (preferably C10-C14), mono- and polyesters of saturated linear C10-C20 acids and branched or unsaturated C1-C20 mono-alcohols (preferably C3-C10); mono- and polyesters of branched or unsaturated C5-C20 acids and of branched or unsaturated C5-C20 mono-alcohols; mono- and polyesters of branched or unsaturated C5-C20 acids and of linear C2-C4 mono-alcohols;
  • C6-C12 fatty acid triglycerides such as caprylic and capric acid triglycerides and triheptanoin;
  • C10-C20 fatty acids such as linoleic acid
  • C10-C20 fatty alcohols such as octyldodecanol and oleyl alcohol
  • squalane C30
  • vegetable squalane extracted from olive oil Cl 5
  • hemisqualane Cl 5
  • dialkyl carbonates such as dicaprylyl carbonate and diethylhexyl carbonate
  • dialkyl ethers such as dicaprylyl ether
  • esters of acids and of monoalcohols mention may in particular be made of monoesters such as the mixture of caprate and caprylate of coconut, ethyl macadamiate, ethyl ester of shea butter, isostearyl isostearate, isononyl isononanoate, ethylhexyl isononanoate, hexyl neopentanoate, ethylhexyl neopentanoate, isostearyl neopentanoate, isodecyl neopentanoate, ethyl myristate, isopropyl myristate, myristate octyldodecyl, isopropyl palmitate, ethylhexyl palmitate, hexyl laurate, isoamyl laurate, cetostearyl nonanoate, propylheptyl caprylate,
  • esters that can be used are the diesters of acids and of monoalcohols such as isopropyl adipate, diethylhexyl adipate, diisopropyl sebacate and diisoamyl sebacate.
  • oils for use in the present invention are mono-alcohol fatty acid esters, such as ethyl myristate and methyl stearate.
  • the oily phase may optionally contain one or more antioxidants in addition to the aforementioned constituents.
  • the perfume can represent 1% to 99% by weight, preferably from 50 to 99% by weight, for example from 80 to 95% by weight or as a variant from 50 to 85% by weight, relative to the total weight of the oily phase.
  • the crosslinking agent can represent 1% to 99% by weight, preferably from 1 to 50% by weight, for example from 5 to 20% by weight or as a variant from 15 to 50% by weight, relative to the total weight of the oily phase.
  • the perfume and the crosslinking agent taken together can represent 1 to 100% by weight, preferably 50 to 100% by weight, for example 80 to 99% by weight, relative to the total weight of the oily phase.
  • the oily phase can be prepared by mixing its constituents.
  • the polyisocyanate type crosslinking agent can be used pure or in solution in a solvent such as ethyl acetate.
  • the formation of the oil-in-water emulsion is carried out by mixing, generally between 10 and 95°C, preferentially between 20 and 50°C and more preferentially between 20 and 30°C, of the phase oily phase with the aqueous phase, generally by adding the oily phase to the aqueous phase.
  • the weight ratio of aqueous phase to oily phase can range from 1:1 to 5:1, preferably from 1:1 to 3:1 and more preferably from 1.5:1 to 2.5:1.
  • the mixture is advantageously carried out with stirring, in particular using a blade or propeller stirrer or a homogenizer, for example at a speed of 100 to 15,000 revolutions / min, preferably from 400 to 1,000 revolutions /min. Stirring is continued throughout the emulsification, which can last from a few minutes to several hours, for example from 1 to 75 minutes and preferably from 5 to 30 minutes, better still from 10 to 20 minutes.
  • the pH of the aqueous phase is preferably between 6 and 11 and, even better, between 8 and 10.
  • the pH can be adjusted in particular by adding an organic or inorganic base such as trimethylamine or triethylamine.
  • the pH adjustment can be done after or before mixing the aqueous and oily phases.
  • an organic or inorganic acid salt of chitosan is used to form, by reaction with the crosslinking agent, the shell of the microcapsules.
  • Chitosan we mean a biopolymer derived from chitin.
  • Chitin is a constituent of the exoskeleton of certain crustaceans (e.g. crabs, shrimps, squids), and also present in certain fungi such as Ascomycetes, Zygomycetes, Basidiomycetes and Deuteromycetes, e.g. Absidia, Mucor, Aspergillus niger, Ganoderma lucidum, or Rhizopus oryzae.
  • Chitosan can be obtained by alkaline or enzymatic deacetylation of chitin, and is in particular characterized by its degree of deacetylation and its molar mass.
  • DA the degree of acetylation
  • the degree of deacetylation of chitosan be greater than or equal to 60% (for example, between 60% and 100%), more preferably greater than or equal to 70% (for example, comprised between 70% and 95%), better still greater than or equal to 80% (for example, between 80% and 90%).
  • the weight average molecular mass of chitosan as determined by Gel Permeation Chromatography (GPC), is preferably less than 50 kDa, for example between 3 and 50 KDa.
  • Chitosan is used according to the invention in the form of an organic acid salt (for example, a salt of acetic acid) or inorganic (for example, a salt of hydrochloric acid).
  • organic acid salt for example, a salt of acetic acid
  • inorganic for example, a salt of hydrochloric acid
  • chitosan will denote, for the purposes of simplicity, such an organic or inorganic acid salt.
  • Chitosan is advantageously used in the form of a powder or an aqueous solution, in particular a viscous aqueous solution or even an aqueous gel.
  • step (b) of heating after the formation of the oil-in-water emulsion, and before step (b) of heating.
  • the aqueous phase further comprises chitosan
  • the oil-in-water emulsion is then formed by mixing the aqueous phase further comprising chitosan with the oily phase, in the conditions described above.
  • the oil-in-water emulsion is formed by mixing the aqueous phase with the oily phase, under the conditions described above, after the chitosan has been added during the formation of the oil-in-water emulsion.
  • the oil-in-water emulsion is formed by mixing the aqueous phase with the oily phase, under the conditions described above, and the chitosan is then added to the oil-in-water emulsion.
  • the chitosan can represent between 0.1% and 3% by weight, preferably between 0.5% and 1.5% by weight, relative to the total weight of the reaction medium.
  • reaction medium is meant the combination of the perfume, the crosslinking agent, optionally one or more oils, water, chitosan and optionally one or more of the aforementioned additives, in particular the stabilizer .
  • the reaction medium does not comprise any other compound and in any case a compound capable of reacting, under the conditions of the crosslinking step below, with chitosan and/or the crosslinking agent.
  • Step (b) of the process of the invention comprises heating the emulsion obtained in step (a) to a temperature above 20°C and below 40°C. This heating step makes it possible to form a polyurethane-based shell around the oily core comprising at least one perfume, by crosslinking the chitosan using the crosslinking agent.
  • This step is generally carried out with stirring at a speed of between 100 and 2000 revolutions/min, preferably from 300 to 1000 revolutions/min.
  • the speed may in particular be identical to that applied to step (a) of emulsification.
  • the duration of the heating in step (b) can be between 1 hour and 20 hours, preferably between 3 hours and 5 hours.
  • the temperature of step (b) of heating is higher than 25°C and lower than 38°C, preferably, higher than 28°C and lower than 37°C, and better still the temperature of step (b) of heating is equal to 35°C.
  • an aqueous suspension of microcapsules is obtained which can be used as such, optionally after concentration.
  • the microcapsules can be collected by centrifugation or filtration, optionally washed with an appropriate solvent, and then dried. They can thus be used in dry form.
  • the microcapsules obtained by the method of the invention have a core-shell structure, the core consisting of an oily phase comprising at least one perfume, and the shell having a structure of the polyurethane type formed by crosslinking chitosan with a polyisocyanate .
  • microcapsules obtained by the method of the invention may in particular have a core/shell weight ratio ranging from 6:1 to 3:1. They are advantageously substantially spherical and have, for example, a median diameter D50 of between 1 and 50 ⁇ m, preferentially from 1 to 30 ⁇ m, more preferentially from 1 to 10 ⁇ m, as measured by laser diffraction, for example using a Mastersizer® 3000 particle size analyzer from Malvern.
  • microcapsules in dry form or in aqueous suspension, are particularly suitable for use as a perfuming additive in a detergent, cosmetic or pharmaceutical composition or in textile materials, paper or cardboard.
  • Example 1 Preparation of perfume microcapsules according to the process of the invention In a reactor, are mixed with stirring at a speed of 800 rpm, for 5 minutes at room temperature:
  • phase consisting of 3 g of polyvinyl alcohol, 71 g of water, and a quantity of base such as trimethylamine or triethylamine or acid such as citric acid allowing the pH to be adjusted to 3.6 or 9; and
  • phase consisting of 60 g of a perfume and 6 g of Bayhydur ® Eco 701-90.
  • aqueous solution of chitosan hydrochloride (2.4 g of chitosan hydrochloride in 57.6 g of water) is added.
  • the resulting mixture is stirred at a speed of 800 rpm for 15 min at room temperature then at a speed of 450 rpm for 4 h at 35°C.
  • An aqueous dispersion of microcapsules is then obtained.
  • Example 2 Evaluation of the perfume microcapsules obtained according to the method of the invention a) A thermogravimetric analysis of the perfume microcapsules obtained according to the method described in Example 1 was carried out in order to determine the percentage of residual product at 230° C. . At this temperature, the oily core, the perfume, the solvents, and degradation products such as residual traces of chitosan, or polyvinyl alcohol are eliminated. To do this, 10 mg of microcapsules in aqueous dispersion are heated from 25°C to 600°C at a rate of 10°C/min under nitrogen (device: TGA 2 Mettler-Toledo equipped with a high sensitivity thermo-balance (within 0.1 pg)).
  • thermogravimetric analysis of the perfume microcapsules obtained according to the method described in Example 1 was carried out under the same conditions as above, in order to determine the temperature (Tio%) at which the residual weight percentage is 10 %, or in other words the temperature at which 90% by weight of the microcapsules is eliminated (Table 2).
  • the olfactory intensity of the microcapsules prepared at 35°C according to the method of the invention is greater than that of the microcapsules prepared at 50°C. It will be noted that the olfactory intensity of the microcapsules obtained at 35° C. is markedly higher at pH 9.
  • the application of a lower heating temperature, and preferably greater than or equal to 6, makes it possible to form a more resistant shell which more effectively protects the perfume, and which therefore makes it possible to improve the olfactory intensity of the microcapsules.

Abstract

The present invention relates to a method for producing fragrance microcapsules, which can be used as they are or in aqueous suspension as a fragrance additive in a detergent, cosmetic or pharmaceutical composition or in textile materials, paper or cardboard.

Description

Procédé de préparation de microcapsules de parfum Method for preparing perfume microcapsules
OBJET DE L’INVENTION OBJECT OF THE INVENTION
La présente invention concerne un procédé de préparation de microcapsules de parfum, qui peuvent être utilisées telles quelles ou en suspension aqueuse comme additif parfumant dans une composition détergente, cosmétique ou pharmaceutique ou dans des matériaux textiles, du papier ou du carton. The present invention relates to a process for the preparation of perfume microcapsules, which can be used as such or in aqueous suspension as a perfume additive in a detergent, cosmetic or pharmaceutical composition or in textile materials, paper or cardboard.
ARRIERE-PLAN DE L’INVENTION BACKGROUND OF THE INVENTION
Il est connu que la micro-encapsulation de parfums, constitués en particulier d'huiles essentielles, permet de les protéger, d'éviter la perte d'ingrédients volatils aromatiques, de contrôler le profil de libération du parfum et d'améliorer sa stabilité (I.T. Carvalho et al., International Journal of Cosmetic Science , 2015, 1-11). Il est ainsi possible de formuler ces parfums dans différentes compositions, notamment des détergents (WO 2015/104469). Le plus souvent, T encapsulation se fait par la copolymérisation de composés à base d’aldéhyde et de polyamine. On utilise principalement les résines aminoplast obtenues par polycondensation d'une polyamine (en général la mélamine, qui est un dérivé de triazine) avec un aldéhyde (la plupart du temps le formaldéhyde) (US 5,137,646). It is known that the micro-encapsulation of perfumes, made up in particular of essential oils, makes it possible to protect them, to avoid the loss of aromatic volatile ingredients, to control the release profile of the perfume and to improve its stability ( I.T. Carvalho et al., International Journal of Cosmetic Science, 2015, 1-11). It is thus possible to formulate these perfumes in different compositions, in particular detergents (WO 2015/104469). Most commonly, encapsulation is done through the copolymerization of aldehyde and polyamine-based compounds. The aminoplast resins obtained by polycondensation of a polyamine (generally melamine, which is a derivative of triazine) with an aldehyde (most of the time formaldehyde) (US 5,137,646) are mainly used.
Bien que ces résines soient efficaces, leur utilisation reste controversée du fait qu’elles utilisent du formaldéhyde, qui peut être retrouvé, s’il n’a pas été consommé lors de la réaction de polymérisation, dans la phase aqueuse contenant les microcapsules. Or, le formaldéhyde est un composé volatil, irritant et considéré comme un cancérogène important par les organismes de santé. De ce fait, sa concentration dans des compositions est soumise à réglementation pour de nombreuses applications. Des systèmes de copolymérisation alternatifs, moins toxiques, ont dû donc être mis au point. Although these resins are effective, their use remains controversial because they use formaldehyde, which can be found, if it has not been consumed during the polymerization reaction, in the aqueous phase containing the microcapsules. However, formaldehyde is a volatile compound, irritating and considered a major carcinogen by health organizations. Therefore, its concentration in compositions is subject to regulation for many applications. Alternative, less toxic copolymerization systems therefore had to be developed.
WO 2019/063515 décrit des microcapsules de parfum dont la paroi est en polyurée/polyuréthane formée par réaction d'un polyisocyanate avec au moins une polyamine dont le chitosan, issu par exemple d 'Aspergillus Niger . Le chitosan utilisé dans ce document est de préférence non protoné et utilisé sous forme de poudre. Les microcapsules sont préparées par un procédé comprenant la formation d’une émulsion huile-dans-eau à partir d’une phase aqueuse à pH basique et une phase huileuse contenant un parfum et un polyisocyanate, puis la formation de l’écorce par ajout de la polyamine, à une température d’au moins 50°C. WO 2019/179939 divulgue des microcapsules de parfum dont la paroi est formée par réaction d'un polyisocyanate avec un amidon modifié et du chitosan. Les microcapsules sont préparées par un procédé comprenant la formation d’une émulsion huile-dans-eau à partir d’une phase aqueuse à pH acide ou basique, et une phase huileuse contenant un parfum et un polyisocyanate, puis la formation de l’écorce par ajout de l’amidon modifié et du chitosan en milieu acide, à une température d’au moins 50°C. WO 2019/063515 describes perfume microcapsules whose wall is made of polyurea/polyurethane formed by reaction of a polyisocyanate with at least one polyamine including chitosan, derived for example from Aspergillus niger. The chitosan used in this document is preferably non-protonated and used in powder form. The microcapsules are prepared by a process comprising the formation of an oil-in-water emulsion from an aqueous phase at basic pH and an oily phase containing a perfume and a polyisocyanate, then the formation of the shell by adding the polyamine, at a temperature of at least 50°C. WO 2019/179939 discloses perfume microcapsules whose wall is formed by reacting a polyisocyanate with a modified starch and chitosan. The microcapsules are prepared by a process comprising the formation of an oil-in-water emulsion from an aqueous phase at acidic or basic pH, and an oily phase containing a perfume and a polyisocyanate, then the formation of the shell by adding the modified starch and the chitosan in an acid medium, at a temperature of at least 50°C.
Ces microcapsules de parfum, qui sont utilisées comme additif parfumant dans des détergents, lessives ou produits cosmétiques, présentent toutefois une intensité olfactive modérée. Il serait donc avantageux de pouvoir disposer de microcapsules de parfum ayant une intensité olfactive améliorée. These perfume microcapsules, which are used as a perfume additive in detergents, detergents or cosmetic products, however have a moderate olfactory intensity. It would therefore be advantageous to be able to have perfume microcapsules having an improved olfactory intensity.
Dans ce contexte, la Demanderesse a démontré que des microcapsules de parfum comprenant une écorce à base de polyuréthane présentaient une intensité olfactive améliorée lorsque la formation de l'écorce était mise en oeuvre à une température plus faible que dans les procédés de l’art antérieur. Ce résultat est d'autant plus surprenant que l'application d'une température plus faible permet habituellement une réticulation moindre et donc une écorce qui offre une moindre protection du parfum encapsulé, de sorte que le parfum a tendance à diffuser lentement hors de l'écorce tout au long du stockage des microcapsules, réduisant ainsi la quantité de parfum disponible lors de l'utilisation des microcapsules et par conséquent l'intensité olfactive du parfum. In this context, the Applicant has demonstrated that perfume microcapsules comprising a polyurethane-based bark exhibited improved olfactory intensity when the formation of the bark was carried out at a lower temperature than in the methods of the prior art. . This result is all the more surprising since the application of a lower temperature usually allows less crosslinking and therefore a bark that offers less protection of the encapsulated perfume, so that the perfume tends to diffuse slowly out of the bark throughout the storage of the microcapsules, thereby reducing the amount of fragrance available when using the microcapsules and therefore the olfactory intensity of the fragrance.
De manière intéressante, la Demanderesse a en outre montré que l'intensité olfactive du parfum était encore améliorée lorsque le procédé est mis en oeuvre à un pH supérieur ou égal à 6, de préférence basique. Interestingly, the Applicant has also shown that the olfactory intensity of the perfume was further improved when the method is implemented at a pH greater than or equal to 6, preferably basic.
Il a déjà été décrit dans le document WO2020/195132 un procédé de préparation de microcapsules de parfum à une température inférieure à 50°C. L’Exemple 21 divulgue ainsi un procédé de fabrication de microcapsules de parfum par mélange d’une phase aqueuse acide, renfermant du chitosan, avec une phase huileuse contenant un parfum, un solvant organique et un agent de réticulation de type isocyanate, pour former une émulsion dont le pH est ensuite ajusté à une valeur basique avant chauffage de l’émulsion à 30°C pour initier la polymérisation. Ce procédé est toutefois complexe, dans la mesure où il nécessite une acidification, puis une neutralisation, du milieu réactionnel. La présente invention vise à procédé un procédé économiquement plus avantageux pour former des microcapsules de parfum présentant une bonne stabilité et une intensité olfactive satisfaisante. Document WO2020/195132 has already described a process for preparing perfume microcapsules at a temperature below 50°C. Example 21 thus discloses a process for manufacturing perfume microcapsules by mixing an acidic aqueous phase, containing chitosan, with an oily phase containing a perfume, an organic solvent and an isocyanate-type crosslinking agent, to form a emulsion whose pH is then adjusted to a basic value before heating the emulsion to 30° C. to initiate the polymerization. This process is however complex, insofar as it requires acidification, then neutralization, of the reaction medium. The present invention aims to provide an economically more advantageous process for forming perfume microcapsules having good stability and satisfactory olfactory intensity.
RESUME DE L’INVENTION SUMMARY OF THE INVENTION
L’invention a donc pour objet un procédé de préparation de microcapsules de parfum comprenant : The subject of the invention is therefore a method for preparing perfume microcapsules comprising:
(a) le mélange d’une phase aqueuse avec une phase huileuse comprenant au moins un parfum et au moins un agent de réticulation de type polyisocyanate, pour former une émulsion huile-dans-eau, (a) mixing an aqueous phase with an oily phase comprising at least one perfume and at least one crosslinking agent of the polyisocyanate type, to form an oil-in-water emulsion,
(b) le chauffage de l’émulsion obtenue à l’étape (a) en présence de chitosan à une température supérieure à 20 °C et inférieure à 40 °C, pour former une écorce à base de polyuréthane autour d’un cœur huileux comprenant ledit au moins un parfum, et (b) heating the emulsion obtained in step (a) in the presence of chitosan at a temperature above 20°C and below 40°C, to form a polyurethane-based shell around an oily core comprising said at least one perfume, and
(c) éventuellement, la récupération et le séchage des microcapsules obtenues à l’étape(c) optionally, recovering and drying the microcapsules obtained in step
(b), le chitosan étant ajouté avant, pendant et/ou après la formation de l’émulsion à l’étape (a), et avant l’étape (b) de chauffage, caractérisé en ce que le chitosan est utilisé sous forme de sel d’acide organique ou inorganique. (b), the chitosan being added before, during and/or after the formation of the emulsion in step (a), and before the heating step (b), characterized in that the chitosan is used in the form organic or inorganic acid salt.
DESCRIPTION DETAILLEE DETAILED DESCRIPTION
La présente invention porte sur un procédé de préparation de microcapsules comprenant une écorce à base de polyuréthane et un cœur huileux comprenant au moins un parfum. Le procédé de l’invention est basé sur deux étapes clés, à savoir : The present invention relates to a process for preparing microcapsules comprising a polyurethane-based shell and an oily core comprising at least one perfume. The process of the invention is based on two key steps, namely:
- la formation d’une émulsion huile-dans-eau, et - the formation of an oil-in-water emulsion, and
- la réticulation d’un polymère naturel, le chitosan, au moyen d’un agent de réticulation, par polycondensation interfaciale, à une température inférieure à 40 °C, pour former une écorce autour des gouttelettes d'huile contenant le parfum. - the crosslinking of a natural polymer, chitosan, using a crosslinking agent, by interfacial polycondensation, at a temperature below 40°C, to form a shell around the oil droplets containing the perfume.
L’émulsion huile-dans-eau est formée à partir d’une phase aqueuse, à laquelle est mélangée une phase huileuse comprenant au moins un parfum et au moins un agent de réticulation de type polyisocyanate (étape (a)). La phase aqueuse de l’étape (a) comprend typiquement de l’eau, et éventuellement un ou plusieurs additifs choisis parmi les émulsifiants, les anti-coalescents, les tensioactifs, les stabilisants et leurs mélanges. The oil-in-water emulsion is formed from an aqueous phase, with which is mixed an oily phase comprising at least one perfume and at least one crosslinking agent of polyisocyanate type (step (a)). The aqueous phase of step (a) typically comprises water, and optionally one or more additives chosen from emulsifiers, anti-coalescents, surfactants, stabilizers and mixtures thereof.
La phase aqueuse comprend avantageusement au moins un stabilisant, c'est-à-dire un gélifiant polymérique hydrophile capable de maintenir les microcapsules en suspension dans la phase aqueuse à l'issue du procédé. La phase aqueuse comprenant un stabilisant peut typiquement être une dispersion formée par mélange d’eau et du stabilisant sous agitation. Le stabilisant peut être utilisé pur, dilué en solution, ou en suspension. La concentration massique en stabilisant dans la phase aqueuse peut être comprise entre 0,1 % et 5 %, de préférence entre 0,3% et 3%, mieux entre 1 et 1,5 %. The aqueous phase advantageously comprises at least one stabilizer, that is to say a hydrophilic polymeric gelling agent capable of maintaining the microcapsules in suspension in the aqueous phase at the end of the process. The aqueous phase comprising a stabilizer can typically be a dispersion formed by mixing water and the stabilizer with stirring. The stabilizer can be used pure, diluted in solution, or in suspension. The mass concentration of stabilizer in the aqueous phase can be between 0.1% and 5%, preferably between 0.3% and 3%, better still between 1 and 1.5%.
Dans un mode de réalisation particulier de l’invention, le stabilisant est choisi parmi les polysaccharides et en particulier la cellulose, un dérivé de cellulose tel que l'hydroxypropyl cellulose ou l'hydroxypropyl méthyl cellulose, les amidons éventuellement modifiés, ou les gommes végétales ; les polyarginines, les lécithines, les lactates, les sorbates, les isosorbates d'esters gras ; les polymères synthétiques tels que la polyvinylpyrrolidone, le poly(oxyde d’éthylène), le poly(oxyde de propylène), le polyalcool vinylique, le poly(sulfonate de styrène), les polymères (méth)acryliques tels que l'acide polyacrylique et ses sels ou l'acide polyacrylamidométhylpropane sulfonique (AMPS) et ses sels, et un mélange de ceux-ci. On préfère que le stabilisant soit un polyalcool vinylique. In a particular embodiment of the invention, the stabilizer is chosen from polysaccharides and in particular cellulose, a cellulose derivative such as hydroxypropyl cellulose or hydroxypropyl methyl cellulose, optionally modified starches, or vegetable gums ; polyarginines, lecithins, lactates, sorbates, fatty ester isosorbates; synthetic polymers such as polyvinylpyrrolidone, poly(ethylene oxide), poly(propylene oxide), polyvinyl alcohol, poly(styrene sulfonate), (meth)acrylic polymers such as polyacrylic acid and its salts or polyacrylamidomethylpropane sulfonic acid (AMPS) and its salts, and a mixture thereof. It is preferred that the stabilizer be a polyvinyl alcohol.
La phase huileuse comprend au moins un parfum et au moins un agent de réticulation de type polyisocyanate. The oily phase comprises at least one perfume and at least one crosslinking agent of the polyisocyanate type.
On entend par "parfum" un composé unique ou un mélange de composés volatils et odoriférants. Ces composés ont une tension de vapeur supérieure à la pression atmosphérique à température ambiante. Ils sont notamment listés dans Merck Index, 8th Edition, Merck & Co., Inc. Rahway, N.J. Ces composés peuvent être d'origine synthétique ou naturelle. Il peut par exemple s'agir d'une ou plusieurs huiles essentielles de plantes, choisies par exemple parmi les Astéracées, les Myrtacées, les Lauracées, les Lamiacées, les Rutacées et les Zingibéracées, qui sont habituellement extraites d'une partie quelconque de ces plantes par extraction à l'aide d'un fluide supercritique, hydrodistillation, enfleurage, entraînement à la vapeur ou tout autre procédé permettant l’extraction de molécules parfumées d’une plante. Qu'ils soient d'origine synthétique ou naturelle, les parfums comprennent en général des composés, éventuellement terpéniques, choisis parmi les alcools, les aldéhydes et les esters. By “perfume” is meant a single compound or a mixture of volatile and odoriferous compounds. These compounds have a vapor pressure above atmospheric pressure at room temperature. They are notably listed in Merck Index, 8th Edition, Merck & Co., Inc. Rahway, NJ These compounds can be of synthetic or natural origin. It may for example be one or more essential oils of plants, chosen for example from Asteraceae, Myrtaceae, Lauraceae, Lamiaceae, Rutaceae and Zingiberaceae, which are usually extracted from any part of these plants by extraction using a supercritical fluid, hydrodistillation, enfleurage, steam distillation or any other process allowing the extraction of fragrant molecules from a plant. Whether they are of synthetic or natural origin, perfumes generally comprise compounds, possibly terpenes, chosen from alcohols, aldehydes and esters.
Les composés parfumants suivants peuvent notamment être utilisés comme parfum dans la présente invention, seuls ou en combinaison : le 2-méthyl butyrate de méthyle ; le 2-méthyl butyrate d'isopropyle ; le 2-méthyl butyrate d'éthyle ; le 2-méthyl pentanoate d'éthyle ; l'heptanoate d'éthyle ; l'octanoate d'éthyle ; l'hexanoate d'isobutyle ; le butyrate d'amyle ; l'heptanoate d'amyle ; l'isobutyrate d'isoamyle ; l'acétate d'hexyle ; le butyrate d'hexyle ; l'isobutyrate d'hexyle ; l'isovalérate d'hexyle ; le propionate d'hexyle ; le 2-cyclohexyl propanoate d'éthyle ; le 3,5,5-triméthyl hexanoate d'éthyle ; le 5-hydroxydécanoate de glycéryle ; l'acétate de prényle ; le 2-butenyl acétate de méthyle ; le 3-nonénoate de méthyle ; le décénoate d'éthyle ; l'octénoate d'éthyle ; le décadiénoate d'éthyle ; l'octénoate d'éthyle ; l'acétate de citronellyle ; l'isovalerate de 2-hex-l-ènyle; le propionate de 2-hexèn-l-yle ; le valérate de 2-hexènen-l-yle ; le (E)-2-hexènoate de 3-hexèn-l-yle ; le 2-méthyl butyrate de 3- hexèn-l-yle ; l'acétate de 3-hexèn-l-yle ; le benzoate de 3-hexèn-l-yle ; le formate de 3-hexèn-l- yle ; le tiglate de 3-hexèn-l-yle ; le 2-méthyl butyrate de 2-méthyl butyle ; l'isovalérate de butyle ; l'allyl cyclohexane ; le propionate d'allyl cyclohexyle ; le valérate d'allyl cyclohexyle ; l'octanoate de benzyle ; la gamma-décalactone ; la gamma-dodécalactone ; la jasmin lactone ; la jasmolactone ; la nonalactone ; le 6-acétoxydihydrotheaspirane ; l'isobutyrate de phenoxy éthyle ; le pivacyclène ; l'anthranilate de diméthyle ; l'antranilate de méthyle ; l'octanal ; le nonanal ; le décanal ; le dodécanal ; le méthyl nonyl acétaldéhyde ; le méthyl octyl acétaldéhyde ; le 2,4-hexadiénal ; l'intreleven ; le décèn-l-al ; le nonèn-l-al ; l'aldoxal ; le géraldéhyde ; l'isocyclo citral ; le d-limonène ; le ligustral ; le tridécénal ; le triplai ; le vertoliff ; le cyclal C; l'héliotropine ; le néocaspirène ; le beta naphthol éthyl éther ; le beta naphthol méthyl éther ; le hyacinth éther ; la 2-heptyl cyclopentanone ; l'undecavertol ; le frutonile ; et leurs mélanges. The following perfuming compounds can in particular be used as perfume in the present invention, alone or in combination: methyl 2-methyl butyrate; isopropyl 2-methyl butyrate; ethyl 2-methyl butyrate; ethyl 2-methyl pentanoate; ethyl heptanoate; ethyl octanoate; isobutyl hexanoate; amyl butyrate; amyl heptanoate; isoamyl isobutyrate; hexyl acetate; hexyl butyrate; hexyl isobutyrate; hexyl isovalerate; hexyl propionate; ethyl 2-cyclohexyl propanoate; ethyl 3,5,5-trimethyl hexanoate; glyceryl 5-hydroxydecanoate; prenyl acetate; methyl 2-butenyl acetate; methyl 3-nonenoate; ethyl decenoate; ethyl octenoate; ethyl decadienoate; ethyl octenoate; citronellyl acetate; 2-hex-1-enyl isovalerate; 2-hexen-1-yl propionate; 2-hexenen-1-yl valerate; 3-hexen-1-yl (E)-2-hexenoate; 3-hexen-1-yl 2-methyl butyrate; 3-hexen-1-yl acetate; 3-hexen-1-yl benzoate; 3-hexen-1-yl formate; 3-hexen-1-yl tiglate; 2-methyl butyl 2-methyl butyrate; butyl isovalerate; allyl cyclohexane; allyl cyclohexyl propionate; allyl cyclohexyl valerate; benzyl octanoate; gamma-decalactone; gamma-dodecalactone; jasmine lactone; jasmolactone; nonalactone; 6-acetoxydihydrotheaspirane; phenoxy ethyl isobutyrate; pivacyclene; dimethyl anthranilate; methyl antranilate; octanal; nonanal; the decanal; the dodecanal; methyl nonyl acetaldehyde; methyl octyl acetaldehyde; 2,4-hexadienal; the inteleven; the decen-l-al; nonen-l-al; aldoxal; geraldehyde; isocyclo citral; d-limonene; the ligustral; the tridecenal; the triplay; the vertoliff; Cyclal C; heliotropin; neocaspirene; beta naphthol ethyl ether; beta naphthol methyl ether; hyacinth ether; 2-heptyl cyclopentanone; undecavertol; frutonil; and their mixtures.
Par « agent de réticulation », on entend un composé polyfonctionnel capable de réagir avec le chitosan. Dans le cadre de la présente invention, l’agent de réticulation est un polyisocyanate, c’est-à-dire un composé comprenant au moins deux fonctions isocyanates (-NCO). Le polyisocyanate peut en particulier comprendre au moins 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 50, 100 ou 250 fonctions isocyanates. De préférence, le polyisocyanate comprend de 2 à 5 fonctions isocyanates. Eventuellement, le polyisocyanate peut comprendre en outre d’autres fonctions, en particulier des fonctions dérivées de la fonction isocyanate, telles que la fonction biuret, isocyanurate, uretdione, iminooxadiazinedione, trimethylol propane, ou plus généralement, des fonctions issues de la réaction d’un isocyanate avec un alcool ou polyol, une amine ou polyamine, ou un thiol ou polythiol. Le polyisocyanate peut avoir une structure monomérique ou polymérique. By “crosslinking agent”, is meant a polyfunctional compound capable of reacting with chitosan. In the context of the present invention, the crosslinking agent is a polyisocyanate, that is to say a compound comprising at least two isocyanate functions (-NCO). The polyisocyanate may in particular comprise at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 50, 100 or 250 isocyanate functions. Preferably, the polyisocyanate comprises from 2 to 5 isocyanate functions. Optionally, the polyisocyanate may also comprise other functions, in particular functions derived from the isocyanate function, such as the biuret function, isocyanurate, uretdione, iminooxadiazinedione, trimethylol propane, or more generally, functions resulting from the reaction of an isocyanate with an alcohol or polyol, an amine or polyamine, or a thiol or polythiol. The polyisocyanate can have a monomeric or polymeric structure.
Le polyisocyanate peut en particulier être un polyisocyanate aliphatique. Par « aliphatique », on entend une chaîne hydrocarbonée, cyclique ou acyclique, linéaire ou ramifiée, ayant éventuellement une ou plusieurs doubles ou triples liaisons carbone-carbone. Le polyisocyanate aliphatique a de préférence de 3 à 26 atomes de carbone (carbone des fonctions NCO inclus). The polyisocyanate can in particular be an aliphatic polyisocyanate. By "aliphatic" is meant a hydrocarbon chain, cyclic or acyclic, linear or branched, optionally having one or more carbon-carbon double or triple bonds. The aliphatic polyisocyanate preferably has from 3 to 26 carbon atoms (carbon of the NCO functions included).
Des exemples de polyisocyanate aliphatique incluent notamment le diisocyanate de pentaméthylène (PDI), un trimère de PDI, un diisocyanate d’hexam éthylène (HDI), 1,5- diisocyanato-2- méthylpentane, l,4-diisocyanato-2,3-diméthylbutane, 2-éthyl-l,4- diisocyanatobutane, 1,4-diisocyanatobutane, 1,3-diisocyanatopropane, 1,10- diisocyanatodécane, 1,2- diisocyanatocyclobutane, triisocyanate de l’ester éthylique de lysine, diisocyanate d’isophorone (IPDI), l,3-bis(isocyanatométhyl)cyclohexane (H6XDI), 1,2- bis(isocyanatométhyl)cyclohexane, l,4-bis(isocyanato-méthyl)cyclohexane, ou méthylènebis(cyclohexyl isocyanate) (H12MDI). Un polyisocyanate aliphatique préféré est le diisocyanate de pentaméthylène. Examples of aliphatic polyisocyanate include pentamethylene diisocyanate (PDI), PDI trimer, hexam ethylene diisocyanate (HDI), 1,5-diisocyanato-2-methylpentane, 1,4-diisocyanato-2,3- dimethylbutane, 2-ethyl-1,4- diisocyanatobutane, 1,4-diisocyanatobutane, 1,3-diisocyanatopropane, 1,10- diisocyanatodecane, 1,2- diisocyanatocyclobutane, lysine ethyl ester triisocyanate, isophorone diisocyanate ( IPDI), l,3-bis(isocyanatomethyl)cyclohexane (H6XDI), 1,2-bis(isocyanatomethyl)cyclohexane, l,4-bis(isocyanato-methyl)cyclohexane, or methylenebis(cyclohexyl isocyanate) (H12MDI). A preferred aliphatic polyisocyanate is pentamethylene diisocyanate.
Le polyisocyanate peut en variante être un polyisocyanate aromatique. On entend par « polyisocyanate aromatique », un polyisocyanate dont les fonctions isocyanates sont directement reliées à un aryle (notamment un phényle). Le polyisocyanate aromatique a de préférence 6 à 26 atomes de carbone (carbone des fonctions NCO inclus). Des exemples de polyisocyanate aromatique incluent notamment le 2,2'-diisocyanate de diphénylméthylène (2,2’-MDI), 4,4'-diisocyanate de diphénylméthylène (4,4’-MDI), 4,4’-dibenzyl diisocyanate (4,4’-DBDI), 2,6-diisocyanate de toluène (2,6-TDI), m-xylylène diisocyanate (m- XDI), 2,4'-diisocyanate de diphénylméthylène (2,4'-MDI), 2,4’-dibenzyl diisocyanate (2,4’- DBDI), 2,4-diisocyanate de toluène (2,4-TDI) ou le méthylidyne tri-p-phénylène triisocyanate. Des polyisocyanates aromatiques préférés sont le 2,6-diisocyanate de toluène (2,6-TDI) ou 2,4- diisocyanate de toluène (2,4-TDI). D'autres polyisocyanates particuliers sont notamment, le tris-N-hexaméthylène isocyanate- isocyanurate, le biuret du hexaméthylène diisocyanate, ou le triméthylol propane du xylylène- diisocyanate. The polyisocyanate can alternatively be an aromatic polyisocyanate. The term “aromatic polyisocyanate” means a polyisocyanate whose isocyanate functions are directly linked to an aryl (in particular a phenyl). The aromatic polyisocyanate preferably has 6 to 26 carbon atoms (carbon of the NCO functions included). Examples of aromatic polyisocyanate include diphenylmethylene 2,2'-diisocyanate (2,2'-MDI), diphenylmethylene 4,4'-diisocyanate (4,4'-MDI), 4,4'-dibenzyl diisocyanate ( 4,4'-DBDI), toluene 2,6-diisocyanate (2,6-TDI), m-xylylene diisocyanate (m-XDI), diphenylmethylene 2,4'-diisocyanate (2,4'-MDI), 2,4'-dibenzyl diisocyanate (2,4'-DBDI), toluene 2,4-diisocyanate (2,4-TDI) or methylidyne tri-p-phenylene triisocyanate. Preferred aromatic polyisocyanates are toluene 2,6-diisocyanate (2,6-TDI) or toluene 2,4-diisocyanate (2,4-TDI). Other particular polyisocyanates are in particular tris-N-hexamethylene isocyanate-isocyanurate, biuret from hexamethylene diisocyanate, or trimethylol propane from xylylene diisocyanate.
Des exemples de polyisocyanates commerciaux sont notamment les produits Desmodur® L75, Desmodur® Eco 7300, ou Bayhydur® Eco 701-90 de Covestro, Takenate® 600, Stabio® D-370N ou D-376N de Mitsui Chemicals Inc, de préférence Desmodur® Eco 7300 ou Bayhydur® Eco 701-90. Examples of commercial polyisocyanates are in particular the products Desmodur ® L75, Desmodur ® Eco 7300, or Bayhydur ® Eco 701-90 from Covestro, Takenate ® 600, Stabio ® D-370N or D-376N from Mitsui Chemicals Inc, preferably Desmodur ® Eco 7300 or Bayhydur® Eco 701-90.
Dans un mode de réalisation préféré, ledit au moins un agent de réticulation de type polyisocyanate est choisi parmi le PDI, un trimère de PDI, et un mélange de celui-ci. In a preferred embodiment, said at least one polyisocyanate crosslinking agent is selected from PDI, a PDI trimer, and a mixture thereof.
La phase huileuse peut être constituée exclusivement du parfum (c'est-à-dire d'un ou plusieurs composés parfumants), et de l’agent de réticulation. En variante, elle peut comprendre une ou plusieurs huiles volatiles et/ou non volatiles quelconques, d'origine végétale et/ou synthétique, en plus du parfum et de l’agent de réticulation. Dans le contexte de cette description, on entend par "huile" un composé liquide à température ambiante (25°C) et pression atmosphérique (105 Pa) qui, lorsqu'il est introduit à raison d'au moins 1% en poids dans l'eau à 25°C, n'est pas du tout soluble dans l'eau, ou soluble à hauteur de moins de 10% en poids, par rapport au poids d'huile introduit dans l'eau. Ces huiles peuvent en particulier être utilisées pour augmenter le caractère hydrophobe de la phase huileuse lorsque le parfum et/ou l’agent de réticulation ne le sont pas suffisamment. The oily phase may consist exclusively of the perfume (that is to say of one or more perfuming compounds), and of the crosslinking agent. Alternatively, it may include any one or more volatile and/or non-volatile oils, of vegetable and/or synthetic origin, in addition to the perfume and the crosslinking agent. In the context of this description, the term "oil" is understood to mean a compound which is liquid at ambient temperature (25° C.) and atmospheric pressure (10 5 Pa) which, when it is introduced at a rate of at least 1% by weight into water at 25° C., is not at all soluble in water, or soluble to the extent of less than 10% by weight, relative to the weight of oil introduced into the water. These oils can in particular be used to increase the hydrophobic character of the oily phase when the perfume and/or the crosslinking agent are not sufficiently hydrophobic.
Des exemples d'huiles volatiles sont les alcanes ramifiés, tels que l'isododécane, et les alcanes linéaires en C10-C13. Examples of volatile oils are branched alkanes, such as isododecane, and linear C10-C13 alkanes.
Comme huiles non volatiles, on peut citer notamment les huiles hydrocarbonées et plus particulièrement : As non-volatile oils, mention may be made in particular of hydrocarbon oils and more particularly:
- les esters d'acides et de mono-alcool choisis parmi : les mono- et polyesters d'acides linéaires saturés en C2-C10 (de préférence en C6-C10) et de mono-alcools linéaires saturés en C10-C18 (de préférence C10-C14), les mono- et polyesters d'acides linéaires saturés en C10-C20 et de mono-alcools ramifiés ou insaturés en C1-C20 (de préférence C3-C10) ; les mono- et polyesters d'acides ramifiés ou insaturés en C5-C20 et de mono-alcools ramifiés ou insaturés en C5-C20 ; les mono- et polyesters d'acides ramifiés ou insaturés en C5-C20 et de mono-alcools linéaires en C2-C4 ; - esters of acids and of mono-alcohol chosen from: mono- and polyesters of saturated linear C2-C10 acids (preferably C6-C10) and of saturated linear C10-C18 mono-alcohols (preferably C10-C14), mono- and polyesters of saturated linear C10-C20 acids and branched or unsaturated C1-C20 mono-alcohols (preferably C3-C10); mono- and polyesters of branched or unsaturated C5-C20 acids and of branched or unsaturated C5-C20 mono-alcohols; mono- and polyesters of branched or unsaturated C5-C20 acids and of linear C2-C4 mono-alcohols;
- les triglycérides d'acides gras en C6-C12, tels que les triglycérides d'acides caprylique et caprique et la triheptanoïne ; - C6-C12 fatty acid triglycerides, such as caprylic and capric acid triglycerides and triheptanoin;
- les acides gras ramifiés et/ou insaturés en C10-C20 (tels que l'acide linoléique) ; - branched and/or unsaturated C10-C20 fatty acids (such as linoleic acid);
- les alcools gras ramifiés et/ou insaturés en C10-C20 (tels que l'octyldodécanol et l'alcool oléylique) ; - branched and/or unsaturated C10-C20 fatty alcohols (such as octyldodecanol and oleyl alcohol);
- les hydrocarbures tels que le squalane (C30), notamment le squalane végétal extrait de l'huile d'olive, et l'hémisqualane (Cl 5) ; - hydrocarbons such as squalane (C30), in particular vegetable squalane extracted from olive oil, and hemisqualane (Cl 5);
- les carbonates de dialkyle, tels que le dicaprylyl carbonate et le diéthylhexyl carbonate ;- dialkyl carbonates, such as dicaprylyl carbonate and diethylhexyl carbonate;
- les dialkyléthers tels que le dicaprylyl éther ; et - dialkyl ethers such as dicaprylyl ether; and
- leurs mélanges. - their mixtures.
On peut également citer les huiles végétales qui contiennent un ou plusieurs des constituants précités. Mention may also be made of vegetable oils which contain one or more of the aforementioned constituents.
Comme esters d'acides et de monoalcools, on peut notamment citer les monoesters tels que le mélange de caprate et caprylate de coco, le macadamiate d'éthyle, l'ester éthylique de beurre de karité, l'isostéarate d'isostéaryle, l'isononanoate d'isononyle, l'isononanoate d'éthylhexyle, le néopentanoate d'hexyle, le néopentanoate d'éthylhexyle, le néopentanoate d'isostéaryle, le néopentanoate d'isodécyle, le myristate d'éthyle, le myristate d'isopropyle, le myristate d'octyldodécyle, le palmitate d'isopropyle, le palmitate d'éthylhexyle, le laurate d'hexyle, le laurate d'isoamyle, le nonanoate de cétostéaryle, le caprylate de propylheptyle,e stéarate de méthyle et leurs mélanges. D'autres esters utilisables sont les diesters d'acides et de monoalcools tels que l'adipate de disopropyle, l'adipate de diéthylhexyle, le sébaçate de diisopropyle et le sébaçate de diisoamyle. As esters of acids and of monoalcohols, mention may in particular be made of monoesters such as the mixture of caprate and caprylate of coconut, ethyl macadamiate, ethyl ester of shea butter, isostearyl isostearate, isononyl isononanoate, ethylhexyl isononanoate, hexyl neopentanoate, ethylhexyl neopentanoate, isostearyl neopentanoate, isodecyl neopentanoate, ethyl myristate, isopropyl myristate, myristate octyldodecyl, isopropyl palmitate, ethylhexyl palmitate, hexyl laurate, isoamyl laurate, cetostearyl nonanoate, propylheptyl caprylate, methyl stearate and mixtures thereof. Other esters that can be used are the diesters of acids and of monoalcohols such as isopropyl adipate, diethylhexyl adipate, diisopropyl sebacate and diisoamyl sebacate.
Des huiles préférées pour une utilisation dans la présente invention sont les esters d'acides gras et de mono-alcool, tels que le myristate d'éthyle et le stéarate de méthyle. La phase huileuse peut éventuellement contenir un ou plusieurs agents anti-oxydants en plus des constituants précités. Preferred oils for use in the present invention are mono-alcohol fatty acid esters, such as ethyl myristate and methyl stearate. The oily phase may optionally contain one or more antioxidants in addition to the aforementioned constituents.
Ainsi, le parfum peut représenter 1% à 99% en poids, préférentiellement de 50 à 99 % en poids, par exemple de 80 à 95% en poids ou en variante de 50 à 85% en poids, par rapport au poids total de la phase huileuse. L’agent de réticulation peut représenter 1% à 99% en poids, préférentiellement de 1 à 50 % en poids, par exemple de 5 à 20 % en poids ou en variante de 15 à 50% en poids, par rapport au poids total de la phase huileuse. Thus, the perfume can represent 1% to 99% by weight, preferably from 50 to 99% by weight, for example from 80 to 95% by weight or as a variant from 50 to 85% by weight, relative to the total weight of the oily phase. The crosslinking agent can represent 1% to 99% by weight, preferably from 1 to 50% by weight, for example from 5 to 20% by weight or as a variant from 15 to 50% by weight, relative to the total weight of the oily phase.
Le parfum et l’agent de réticulation pris ensemble peuvent représenter 1 à 100 % en poids, de préférence de 50 à 100% en poids, par exemple de 80 à 99% en poids, par rapport au poids total de la phase huileuse. The perfume and the crosslinking agent taken together can represent 1 to 100% by weight, preferably 50 to 100% by weight, for example 80 to 99% by weight, relative to the total weight of the oily phase.
La phase huileuse peut être préparée par mélange de ses constituants. L’agent de réticulation de type polyisocyanate peut être utilisé pur ou en solution dans un solvant tel que l’acétate d’éthyle. The oily phase can be prepared by mixing its constituents. The polyisocyanate type crosslinking agent can be used pure or in solution in a solvent such as ethyl acetate.
La formation de l'émulsion huile-dans-eau (ou « émulsification ») est réalisée par mélange, généralement entre 10 et 95°C, préférentiellement entre 20 et 50°C et plus préférentiellement entre 20 et 30°C, de la phase huileuse avec la phase aqueuse, généralement en ajoutant la phase huileuse à la phase aqueuse. Le rapport en poids de la phase aqueuse à la phase huileuse peut aller de 1:1 à 5:1, préférentiellement de 1:1 à 3:1 et plus préférentiellement de 1,5:1 à 2,5:1. Le mélange est avantageusement réalisé sous agitation, notamment à l'aide d'un agitateur à pale ou à hélice ou d'un homogénéisateur, par exemple à une vitesse de 100 à 15 000 tours/min, de préférence de 400 à 1 000 tours/min. L'agitation est poursuivie pendant toute l'émulsification, qui peut durer de quelques minutes à plusieurs heures, par exemple de 1 à 75 minutes et préférentiellement de 5 à 30 minutes, mieux, de 10 à 20 minutes. The formation of the oil-in-water emulsion (or "emulsification") is carried out by mixing, generally between 10 and 95°C, preferentially between 20 and 50°C and more preferentially between 20 and 30°C, of the phase oily phase with the aqueous phase, generally by adding the oily phase to the aqueous phase. The weight ratio of aqueous phase to oily phase can range from 1:1 to 5:1, preferably from 1:1 to 3:1 and more preferably from 1.5:1 to 2.5:1. The mixture is advantageously carried out with stirring, in particular using a blade or propeller stirrer or a homogenizer, for example at a speed of 100 to 15,000 revolutions / min, preferably from 400 to 1,000 revolutions /min. Stirring is continued throughout the emulsification, which can last from a few minutes to several hours, for example from 1 to 75 minutes and preferably from 5 to 30 minutes, better still from 10 to 20 minutes.
Le pH de la phase aqueuse est de préférence compris entre 6 et 11 et, mieux encore, entre 8 et 10. Le pH peut être ajusté notamment par ajout d'une base organique ou inorganique telle que la triméthylamine ou la triéthylamine. L'ajustement du pH peut se faire après ou avant mélange des phases aqueuse et huileuse. The pH of the aqueous phase is preferably between 6 and 11 and, even better, between 8 and 10. The pH can be adjusted in particular by adding an organic or inorganic base such as trimethylamine or triethylamine. The pH adjustment can be done after or before mixing the aqueous and oily phases.
Dans le procédé de l’invention, un sel d’acide organique ou inorganique de chitosan est utilisé pour former, par réaction avec l’agent de réticulation, l’écorce des microcapsules. In the process of the invention, an organic or inorganic acid salt of chitosan is used to form, by reaction with the crosslinking agent, the shell of the microcapsules.
Par “chitosan”, on entend un biopolymère dérivé de la chitine. La chitine est un constituant de l’exosquelette de certains crustacées (crabes, crevettes, calamars, par exemple), et présent également dans certains champignons tels que les Ascomycètes, Zygomycètes, Basidiomycètes et Deutéromycètes, par exemple Absidia, Mucor , Aspergillus niger, Ganoderma lucidum , ou Rhizopus oryzae. Le chitosan peut être obtenu par désacétylation alcaline ou enzymatique de la chitine, et est en particulier caractérisé par son degré de désacétylation et sa masse molaire. Le degré de désacétylation (DD) peut être défini comme suit : DD = 100 - DA en %, où DA est le degré d’acétylation c’est-à-dire le nombre de motifs acétylés (motifs N-acétylglucosamine) sur le nombre total de motifs du polymère chitosan. Dans le cadre de la présente invention, on préfère que le degré de désacétylation du chitosan soit supérieur ou égal à 60% (par exemple, compris entre 60% et 100%), plus préférentiellement supérieur ou égal à 70% (par exemple, compris entre 70% et 95 %), mieux encore supérieur ou égal à 80% (par exemple, compris entre 80% et 90 %). La masse moléculaire moyenne en poids du chitosan, telle que déterminée par Chromatographie par Perméation de Gel (CPG), est de préférence inférieure à 50 kDa, par exemple comprise entre 3 et 50 KDa. By “chitosan”, we mean a biopolymer derived from chitin. Chitin is a constituent of the exoskeleton of certain crustaceans (e.g. crabs, shrimps, squids), and also present in certain fungi such as Ascomycetes, Zygomycetes, Basidiomycetes and Deuteromycetes, e.g. Absidia, Mucor, Aspergillus niger, Ganoderma lucidum, or Rhizopus oryzae. Chitosan can be obtained by alkaline or enzymatic deacetylation of chitin, and is in particular characterized by its degree of deacetylation and its molar mass. The degree of deacetylation (DD) can be defined as follows: DD = 100 - DA in %, where DA is the degree of acetylation, i.e. the number of acetylated units (N-acetylglucosamine units) out of the number total units of the chitosan polymer. In the context of the present invention, it is preferred that the degree of deacetylation of chitosan be greater than or equal to 60% (for example, between 60% and 100%), more preferably greater than or equal to 70% (for example, comprised between 70% and 95%), better still greater than or equal to 80% (for example, between 80% and 90%). The weight average molecular mass of chitosan, as determined by Gel Permeation Chromatography (GPC), is preferably less than 50 kDa, for example between 3 and 50 KDa.
Le chitosan est utilisé selon l’invention sous la forme d’un sel d’acide organique (par exemple, un sel d’acide acétique) ou inorganique (par exemple, un sel d’acide chlorhydrique). Dans le contexte de cette description, on désignera par « chitosan », à des fins de simplicité, un tel sel d’acide organique ou inorganique. Chitosan is used according to the invention in the form of an organic acid salt (for example, a salt of acetic acid) or inorganic (for example, a salt of hydrochloric acid). In the context of this description, the term “chitosan” will denote, for the purposes of simplicity, such an organic or inorganic acid salt.
Le chitosan est avantageusement utilisé sous la forme d’une poudre ou d’une solution aqueuse, en particulier une solution aqueuse visqueuse voire un gel aqueux. Chitosan is advantageously used in the form of a powder or an aqueous solution, in particular a viscous aqueous solution or even an aqueous gel.
Le chitosan peut être ajouté : Chitosan can be added:
- avant la formation de l’émulsion huile-dans-eau, et/ou - before the formation of the oil-in-water emulsion, and/or
- pendant la formation de l’émulsion huile-dans-eau, et/ou - during the formation of the oil-in-water emulsion, and/or
- après la formation de l’émulsion huile-dans-eau, et avant l’étape (b) de chauffage. - after the formation of the oil-in-water emulsion, and before step (b) of heating.
Dans une première forme d’exécution de l’invention, la phase aqueuse comprend en outre le chitosan, et l’émulsion huile-dans-eau est ensuite formée par mélange de la phase aqueuse comprenant en outre le chitosan avec la phase huileuse, dans les conditions décrites ci-dessus. In a first embodiment of the invention, the aqueous phase further comprises chitosan, and the oil-in-water emulsion is then formed by mixing the aqueous phase further comprising chitosan with the oily phase, in the conditions described above.
Dans une seconde forme d’exécution de l’invention, l’émulsion huile-dans-eau est formée par mélange de la phase aqueuse avec la phase huileuse, dans les conditions décrites ci-dessus, après que le chitosan ait été ajouté pendant la formation de l’émulsion huile-dans-eau. Dans une troisième forme d’exécution de l’invention, l’émulsion huile-dans-eau est formée par mélange de la phase aqueuse avec la phase huileuse, dans les conditions décrites ci-dessus, et le chitosan est ensuite ajouté à l’émulsion huile-dans-eau. In a second embodiment of the invention, the oil-in-water emulsion is formed by mixing the aqueous phase with the oily phase, under the conditions described above, after the chitosan has been added during the formation of the oil-in-water emulsion. In a third embodiment of the invention, the oil-in-water emulsion is formed by mixing the aqueous phase with the oily phase, under the conditions described above, and the chitosan is then added to the oil-in-water emulsion.
Le chitosan peut représenter entre 0,1 % et 3 % en poids, de préférence entre 0,5 % et 1,5 % en poids, par rapport au poids total du milieu réactionnel. The chitosan can represent between 0.1% and 3% by weight, preferably between 0.5% and 1.5% by weight, relative to the total weight of the reaction medium.
Par "milieu réactionnel", on entend la combinaison du parfum, de l'agent de réticulation, éventuellement d'une ou plusieurs huiles, de l'eau, du chitosan et éventuellement d'un ou plusieurs des additifs précités, en particulier le stabilisant. Dans une forme d'exécution préférée de l'invention, le milieu réactionnel ne comprend pas d'autre composé et en tout état de cause de composé capable de réagir, dans les conditions de l'étape de réticulation ci-dessous, avec le chitosan et/ou l'agent de réticulation. By "reaction medium" is meant the combination of the perfume, the crosslinking agent, optionally one or more oils, water, chitosan and optionally one or more of the aforementioned additives, in particular the stabilizer . In a preferred embodiment of the invention, the reaction medium does not comprise any other compound and in any case a compound capable of reacting, under the conditions of the crosslinking step below, with chitosan and/or the crosslinking agent.
L’étape (b) du procédé de l’invention comprend le chauffage de l’émulsion obtenue à l’étape (a) à une température supérieure à 20 °C et inférieure à 40 °C. Cette étape de chauffage permet de former une écorce à base de polyuréthane autour du cœur huileux comprenant au moins un parfum, par réticulation du chitosan à l’aide de l’agent de réticulation. Step (b) of the process of the invention comprises heating the emulsion obtained in step (a) to a temperature above 20°C and below 40°C. This heating step makes it possible to form a polyurethane-based shell around the oily core comprising at least one perfume, by crosslinking the chitosan using the crosslinking agent.
Cette étape est généralement mise en œuvre sous agitation à une vitesse comprise entre 100 et 2 000 tours/min, de préférence de 300 à 1 000 tours/min. La vitesse peut notamment être identique à celle appliquée à l’étape (a) d’émulsification. La durée du chauffage à l’étape (b) peut être comprise entre 1 heure et 20 heures, de préférence entre 3 heures et 5 heures. This step is generally carried out with stirring at a speed of between 100 and 2000 revolutions/min, preferably from 300 to 1000 revolutions/min. The speed may in particular be identical to that applied to step (a) of emulsification. The duration of the heating in step (b) can be between 1 hour and 20 hours, preferably between 3 hours and 5 hours.
Dans un mode de réalisation particulier, la température de l’étape (b) de chauffage est supérieure à 25 °C et inférieure à 38 °C, de préférence, supérieure à 28 °C et inférieure à 37 °C, et mieux encore la température de l’étape (b) de chauffage est égale à 35 °C. In a particular embodiment, the temperature of step (b) of heating is higher than 25°C and lower than 38°C, preferably, higher than 28°C and lower than 37°C, and better still the temperature of step (b) of heating is equal to 35°C.
A l'issue de ce procédé, on obtient une suspension aqueuse de microcapsules qui peuvent être utilisées telles quelles, éventuellement après concentration. En variante, les microcapsules peuvent être collectées par centrifugation ou filtration, éventuellement lavées avec un solvant approprié, puis séchées. Elles peuvent ainsi être utilisées sous forme sèche. Les microcapsules obtenues par le procédé de l’invention présentent une structure cœur-écorce, le cœur étant constitué d’un phase huileuse comprenant au moins un parfum, et l’écorce ayant une structure de type polyuréthane formée par réticulation du chitosan avec un polyisocyanate. At the end of this process, an aqueous suspension of microcapsules is obtained which can be used as such, optionally after concentration. Alternatively, the microcapsules can be collected by centrifugation or filtration, optionally washed with an appropriate solvent, and then dried. They can thus be used in dry form. The microcapsules obtained by the method of the invention have a core-shell structure, the core consisting of an oily phase comprising at least one perfume, and the shell having a structure of the polyurethane type formed by crosslinking chitosan with a polyisocyanate .
Les microcapsules obtenues par le procédé de l'invention peuvent en particulier présenter un rapport en poids coeur/écorce allant de 6:1 à 3:1. Elles sont avantageusement sensiblement sphériques et présentent par exemple un diamètre médian D50 compris entre 1 et 50 pm, préférentiellement de 1 à 30 pm, plus préférentiellement de 1 à 10 pm, tel que mesuré par diffraction laser, par exemple à l'aide d'un granulomètre Mastersizer® 3000 de Malvern. The microcapsules obtained by the method of the invention may in particular have a core/shell weight ratio ranging from 6:1 to 3:1. They are advantageously substantially spherical and have, for example, a median diameter D50 of between 1 and 50 μm, preferentially from 1 to 30 μm, more preferentially from 1 to 10 μm, as measured by laser diffraction, for example using a Mastersizer® 3000 particle size analyzer from Malvern.
Ces microcapsules, sous forme sèche ou en suspension aqueuse, sont particulièrement adaptées à une utilisation comme additif parfumant dans une composition détergente, cosmétique ou pharmaceutique ou dans des matériaux textiles, du papier ou du carton. These microcapsules, in dry form or in aqueous suspension, are particularly suitable for use as a perfuming additive in a detergent, cosmetic or pharmaceutical composition or in textile materials, paper or cardboard.
EXEMPLES EXAMPLES
L’invention sera mieux comprise à la lumière des exemples suivants, qui sont donnés à titre purement illustratif et n’ont pas pour but de limiter la portée de l’invention, définie par les revendications annexées. The invention will be better understood in the light of the following examples, which are given for purely illustrative purposes and are not intended to limit the scope of the invention, defined by the appended claims.
Exemple 1 : Préparation de microcapsules de parfum selon le procédé de l'invention Dans un réacteur, sont mélangées sous agitation à une vitesse de 800 tours/min, pendant 5 minutes à température ambiante : Example 1: Preparation of perfume microcapsules according to the process of the invention In a reactor, are mixed with stirring at a speed of 800 rpm, for 5 minutes at room temperature:
- une phase constituée de 3 g d’alcool poly vinylique, 71 g d’eau, et une quantité de base telle que la triméthylamine ou triéthylamine ou d’acide tel que l’acide citrique permettant d’ajuster le pH à 3, 6 ou 9 ; et - a phase consisting of 3 g of polyvinyl alcohol, 71 g of water, and a quantity of base such as trimethylamine or triethylamine or acid such as citric acid allowing the pH to be adjusted to 3.6 or 9; and
- une phase constituée de 60 g d’un parfum et 6 g de Bayhydur® Eco 701-90. - a phase consisting of 60 g of a perfume and 6 g of Bayhydur ® Eco 701-90.
Est ensuite ajoutée une solution aqueuse de chlorhydrate de chitosan (2,4 g de chlorhydrate de chitosan dans 57,6 g d’eau). Le mélange résultant est agité à une vitesse de 800 tours/min, pendant 15 min à température ambiante puis à une vitesse de 450 tours/min pendant 4 h à 35 °C. Une dispersion aqueuse de microcapsules est alors obtenue. Then an aqueous solution of chitosan hydrochloride (2.4 g of chitosan hydrochloride in 57.6 g of water) is added. The resulting mixture is stirred at a speed of 800 rpm for 15 min at room temperature then at a speed of 450 rpm for 4 h at 35°C. An aqueous dispersion of microcapsules is then obtained.
Exemple 2 : Evaluation des microcapsules de parfum obtenues selon le procédé de l'invention a) Une analyse thermogravimétrique des microcapsules de parfum obtenues selon le procédé décrit à l'Exemple 1 a été réalisée afin de déterminer le pourcentage de produit résiduel à 230°C. A cette température, le coeur huileux, le parfum, les solvants, et produits de dégradation tels que les traces résiduelles de chitosan, ou d’alcool polyvinylique sont éliminés. Pour ce faire, 10 mg de microcapsules en dispersion aqueuse sont chauffées de 25 °C à 600 °C à une vitesse de 10 °C/min sous azote (appareil : TGA 2 Mettler-Toledo équipé d’une thermo-balance de haute sensibilité (à 0,1 pg près)). Example 2: Evaluation of the perfume microcapsules obtained according to the method of the invention a) A thermogravimetric analysis of the perfume microcapsules obtained according to the method described in Example 1 was carried out in order to determine the percentage of residual product at 230° C. . At this temperature, the oily core, the perfume, the solvents, and degradation products such as residual traces of chitosan, or polyvinyl alcohol are eliminated. To do this, 10 mg of microcapsules in aqueous dispersion are heated from 25°C to 600°C at a rate of 10°C/min under nitrogen (device: TGA 2 Mettler-Toledo equipped with a high sensitivity thermo-balance (within 0.1 pg)).
Une analyse similaire a été réalisée pour des microcapsules préparées par le même procédé, mais dans lequel l'étape de chauffage est réalisée à TCh= 50 °C (Tableau 1). A similar analysis was carried out for microcapsules prepared by the same method, but in which the heating step is carried out at T Ch = 50° C. (Table 1).
L'écorce représente 5,3 % en poids de l’échantillon. [Tableau 1] The bark represents 5.3% by weight of the sample. [Table 1]
Ces résultats montrent que, quel que ce soit le pH, l'écorce des microcapsules préparées à TCh= 35 °C reste intacte à 230 °C. Au contraire, quel que soit le pH, une perte de masse est observée pour les microcapsules préparées à TCh = 50 °C, traduisant une dégradation du polymère constituant l'écorce. b) Une analyse thermogravimétrique des microcapsules de parfum obtenues selon le procédé décrit à l'Exemple 1 a été réalisée dans les mêmes conditions que ci-dessus, afin de déterminer la température (Tio%) à laquelle le pourcentage en poids résiduel est de 10%, ou en d'autres termes la température à laquelle 90 % en poids des microcapsules est éliminé (Tableau 2). These results show that, whatever the pH, the shell of the microcapsules prepared at T Ch = 35°C remains intact at 230°C. On the contrary, whatever the pH, a loss of mass is observed for the microcapsules prepared at T Ch = 50° C., reflecting a degradation of the polymer constituting the shell. b) A thermogravimetric analysis of the perfume microcapsules obtained according to the method described in Example 1 was carried out under the same conditions as above, in order to determine the temperature (Tio%) at which the residual weight percentage is 10 %, or in other words the temperature at which 90% by weight of the microcapsules is eliminated (Table 2).
[Tableau 2] Ces résultats montrent que, quel que ce soit le pH, la température à laquelle 90% en poids des microcapsules est éliminé, est plus élevée pour les microcapsules préparées à 35 °C selon le procédé de l'invention, que pour les microcapsules préparées à 50 °C. Ces résultats démontrent que l'écorce des microcapsules préparées à 35 °C est plus résistante que celles des microcapsules préparées à 50 °C. Ils démontrent également que l’écorce des microcapsules préparées à pH 6-9 est plus résistante que celle des microcapsules préparées à pH 3. [Table 2] These results show that, whatever the pH, the temperature at which 90% by weight of the microcapsules is eliminated, is higher for the microcapsules prepared at 35° C. according to the process of the invention, than for the microcapsules prepared at 50°C. These results demonstrate that the shell of the microcapsules prepared at 35°C is more resistant than that of the microcapsules prepared at 50°C. They also demonstrate that the shell of microcapsules prepared at pH 6-9 is more resistant than that of microcapsules prepared at pH 3.
Sans vouloir être lié par cette théorie, il semble que cette plus haute résistance de l'écorce soit le résultat d'une meilleure réticulation du chitosan par le polyisocyanate. c) Pour mesurer l'intensité olfactive des microcapsules de parfum, une quantité fixe (150 mg) de microcapsules en dispersion aqueuse a été appliquée sur un support en papier. Après un séchage du support pendant 30 minutes, un test olfactif a été réalisé en frottant avec une force constante le support à l'aide d'une cartonnette puis en faisant évaluer par des panélistes entraînés l'intensité de l'odeur dégagée (Tableau 3). Without wishing to be bound by this theory, it seems that this higher resistance of the bark is the result of better cross-linking of the chitosan by the polyisocyanate. c) To measure the olfactory intensity of the perfume microcapsules, a fixed quantity (150 mg) of microcapsules in aqueous dispersion was applied to a paper support. After the medium had dried for 30 minutes, an olfactory test was carried out by rubbing the medium with a constant force using a small piece of cardboard and then having trained panelists evaluate the intensity of the odor released (Table 3 ).
[Tableau 3] [Table 3]
Quel que soit le pH, l'intensité olfactive des microcapsules préparées à 35 °C selon le procédé de l'invention, est supérieure à celle des microcapsules préparées à 50 °C. On notera que l'intensité olfactive des microcapsules obtenues à 35°C est nettement plus élevée à pH 9. Whatever the pH, the olfactory intensity of the microcapsules prepared at 35°C according to the method of the invention is greater than that of the microcapsules prepared at 50°C. It will be noted that the olfactory intensity of the microcapsules obtained at 35° C. is markedly higher at pH 9.
Ainsi, de manière surprenante, l'application d'une température de chauffage plus faible, et de préférence d’un supérieur ou égal à 6, permet de former une écorce plus résistante qui protège plus efficacement le parfum, et qui permet donc d'améliorer l'intensité olfactive des microcapsules. Thus, surprisingly, the application of a lower heating temperature, and preferably greater than or equal to 6, makes it possible to form a more resistant shell which more effectively protects the perfume, and which therefore makes it possible to improve the olfactory intensity of the microcapsules.

Claims

Revendications Claims
1. Procédé de préparation de microcapsules de parfum comprenant : 1. Process for preparing perfume microcapsules comprising:
(a) le mélange d’une phase aqueuse avec une phase huileuse comprenant au moins un parfum et au moins un agent de réticulation de type polyisocyanate, pour former une émulsion huile-dans-eau, (a) mixing an aqueous phase with an oily phase comprising at least one perfume and at least one crosslinking agent of the polyisocyanate type, to form an oil-in-water emulsion,
(b) le chauffage de l’émulsion obtenue à l’étape (a) en présence de chitosan à une température supérieure à 20 °C et inférieure à 40 °C, pour former une écorce à base de polyuréthane autour d’un cœur huileux comprenant ledit au moins un parfum, et (b) heating the emulsion obtained in step (a) in the presence of chitosan at a temperature above 20°C and below 40°C, to form a polyurethane-based shell around an oily core comprising said at least one perfume, and
(c) éventuellement, la récupération et le séchage des microcapsules obtenues à l’étape(c) optionally, recovering and drying the microcapsules obtained in step
(b), le chitosan étant ajouté avant, pendant et/ou après la formation de l’émulsion à l’étape (a), et avant l’étape (b) de chauffage, caractérisé en ce que le chitosan est utilisé sous forme de sel d’acide organique ou inorganique. (b), the chitosan being added before, during and/or after the formation of the emulsion in step (a), and before the heating step (b), characterized in that the chitosan is used in the form organic or inorganic acid salt.
2. Procédé selon la revendication 1, dans lequel la température de l’étape (b) de chauffage est supérieure à 25 °C et inférieure à 38 °C, de préférence supérieure à 28 °C et inférieure à 37 °C, mieux encore la température de l’étape (b) de chauffage est égale à 35 °C. 2. Process according to claim 1, in which the temperature of step (b) of heating is higher than 25°C and lower than 38°C, preferably higher than 28°C and lower than 37°C, more preferably the temperature of step (b) of heating is equal to 35°C.
3. Procédé selon la revendication 1 ou 2, dans lequel le pH de la phase aqueuse est compris entre 3 et 12, de préférence entre 6 et 11 et plus préférentiellement entre 8 et 10. 3. Method according to claim 1 or 2, in which the pH of the aqueous phase is between 3 and 12, preferably between 6 and 11 and more preferably between 8 and 10.
4. Procédé selon l’une quelconque des revendications 1 à 3, dans lequel ledit au moins un agent de réticulation de type polyisocyanate est un polyisocyanate aliphatique ou aromatique. 4. Method according to any one of claims 1 to 3, wherein said at least one polyisocyanate type crosslinking agent is an aliphatic or aromatic polyisocyanate.
5. Procédé selon la revendication 4, dans lequel ledit au moins un agent de réticulation de type polyisocyanate est choisi parmi le PDI, un trimère de PDI, et un mélange de celui-ci. 5. Process according to claim 4, in which said at least one polyisocyanate type crosslinking agent is chosen from PDI, a PDI trimer, and a mixture thereof.
6. Procédé selon l’une quelconque des revendications 1 à 5, dans lequel la durée du chauffage à l’étape (b) est comprise entre 1 heure et 20 heures, de préférence entre 3 heures et 5 heures. 6. Method according to any one of claims 1 to 5, in which the duration of the heating in step (b) is between 1 hour and 20 hours, preferably between 3 hours and 5 hours.
7. Procédé selon l’une quelconque des revendications 1 à 6, dans lequel ledit chitosan est utilisé sous la forme d’une poudre ou d’une solution aqueuse, et a de préférence un degré de désacétylation supérieur ou égal à 60%. 7. Method according to any one of claims 1 to 6, wherein said chitosan is used in the form of a powder or an aqueous solution, and preferably has a degree of deacetylation greater than or equal to 60%.
8. Procédé selon l’une quelconque des revendications 1 à 7, dans lequel la phase aqueuse de l’étape (a) comprend au moins un stabilisant. 8. Method according to any one of claims 1 to 7, in which the aqueous phase of step (a) comprises at least one stabilizer.
9. Procédé selon la revendication 8, dans lequel le stabilisant est choisi parmi les polysaccharides et en particulier la cellulose, un dérivé de cellulose tel que l'hydroxypropyl cellulose ou l'hydroxypropyl méthyl cellulose, les amidons éventuellement modifiés, ou les gommes végétales ; les polyarginines, les lécithines, les lactates, les sorbates, les isosorbates d'esters gras ; les polymères synthétiques tels que la polyvinylpyrrolidone, le poly(oxyde d’éthylène), le poly(oxyde de propylène), le polyalcool vinylique, le poly(sulfonate de styrène), les polymères (méth)acryliques tels que l'acide polyacrylique et ses sels ou l'acide polyacrylamidométhylpropane sulfonique (AMPS) et ses sels, et un mélange de ceux-ci, de préférence un polyalcool vinylique. 9. Process according to claim 8, in which the stabilizer is chosen from polysaccharides and in particular cellulose, a cellulose derivative such as hydroxypropyl cellulose or hydroxypropyl methyl cellulose, optionally modified starches, or vegetable gums; polyarginines, lecithins, lactates, sorbates, fatty ester isosorbates; synthetic polymers such as polyvinylpyrrolidone, poly(ethylene oxide), poly(propylene oxide), polyvinyl alcohol, poly(styrene sulfonate), (meth)acrylic polymers such as polyacrylic acid and its salts or polyacrylamidomethylpropane sulfonic acid (AMPS) and its salts, and a mixture thereof, preferably a polyvinyl alcohol.
EP21810048.5A 2020-11-30 2021-11-22 Method for producing fragrance microcapsules Pending EP4251314A1 (en)

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FR2012357A FR3116735B1 (en) 2020-11-30 2020-11-30 Process for preparing perfume microcapsules
PCT/EP2021/082544 WO2022112189A1 (en) 2020-11-30 2021-11-22 Method for producing fragrance microcapsules

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US5137646A (en) 1989-05-11 1992-08-11 The Procter & Gamble Company Coated perfume particles in fabric softener or antistatic agents
FR3016303B1 (en) 2014-01-10 2016-01-01 Microcapsules Technologies PROCESS FOR PRODUCING DOUBLE-WALLED MICROCAPSULES, MICROCAPSULES PREPARED THEREBY AND USE THEREOF
GB201715535D0 (en) 2017-09-26 2017-11-08 Givaudan Sa Improvements in or relating to organic compounds
CN111526939B (en) 2018-03-19 2023-06-09 弗门尼舍有限公司 Method for preparing microcapsule
EP3799953A4 (en) * 2018-07-03 2021-07-21 LG Household & Health Care Ltd. Method for preparing organic/inorganic hybrid microcapsule
KR102145537B1 (en) * 2018-07-03 2020-08-18 주식회사 엘지생활건강 METHOD FOR PRREPARING Organic-inorganic hybrid micro-capsule
WO2020195132A1 (en) * 2019-03-28 2020-10-01 富士フイルム株式会社 Perfume microcapsules, perfume microcapsule composition, softener, and detergent
EP4103623A4 (en) * 2020-02-14 2024-03-13 Encapsys Llc Articles of manufacture with polyurea capsules cross-linked with chitosan

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