Microcapsules containing agrochemical ingredients

Abstract

The present invention relates to a solid cross-linked microcapsule encapsulating agrochemical ingredient or agrochemical preparation having a mean diameter from 0.5 µm to 50 µm, said microcapsule comprising: - a core consisting of a composition C1 comprising at least one agrochemical ingredient or agrochemical preparation, and - a solid cross-linked polymer envelope totally encapsulating the core at its periphery, said solid cross-linked polymer envelope being made of a biodegradable cross-linked polymer, said polymer being an aliphatic nonaromatic polymer obtained by polymerizing one or several oligomer(s) or monomer(s), and wherein the average thickness of said solid cross-linked polymer envelope is from 5% to 30% of the average diameter of said solid cross-linked microcapsule.

Description

[0001] MICROCAPSULES CONTAINING AGROCHEMICAL INGREDIENTS

[0002] The present invention concerns microcapsules containing at least one agrochemical ingredient or agrochemical preparation as well as stable formulations comprising said microcapsules and application methods using said stable formulations.

[0003] The encapsulation of agrochemical ingredients or agrochemical preparations for plant health products presents significant advantages relative to an unencapsulated agrochemical ingredient in that encapsulation provides a mechanism of controlled release of the agrochemical ingredient in an agricultural field. Controlled release over time of the agrochemical ingredient allow to optimize efficacy of the agrochemical ingredient by improving residual efficacy of the plant protection or nutrition product and thus reducing the required amount of agrochemical ingredient by limiting loss and reducing the number of treatments needed.

[0004] Compatibility enhancement is another feature of encapsulation. This includes physicochemical compatibility, like avoiding chemical degradation or poor dispersion of antagonistic components. Very important is also the mitigation of plant compatibility problems caused by specific active properties or high concentrations in the spray or doses per area on the target organism, respectively. For instance, these compatibility problems are particularly true for the strongly increasing drone application, where agrochemical products are applied highly concentrated in only 10 liter per hectare.

[0005] The encapsulation of agrochemical ingredient also presents significant advantages in that encapsulation limits the volatility of the agrochemical ingredients in the case of volatile compounds. By limiting volatility, encapsulation reduces loss of agrochemical ingredients to the air with typically rapid photodegradation or the risk of dry or wet deposition to water surfaces or other non-targeted environment.

[0006] In the case of volatile agrochemical ingredients, limitation of volatility and controlled release of agricultural agents can contribute to mitigating spray drift damage. Drift is here understood as the movement of plant protection or nutrition products as dust or droplets through the air at the time of application or soon after, to any site, as defined by for instance the US Environmental Protection Agency (https: / / www.epa.gov / reducing-pesticide-drift / introduction-pesticide-drift). Such drift has a variety of negative consequences, namely:

[0007] - health risks due to undesired exposure of human beings to agrochemical ingredients,

[0008] - environmental risks due to undesirable exposure of Wildlife, plants, and streams and other water bodies to agrochemical ingredients, and

[0009] - economic effects of drift such as undesirable exposure of crops to agrochemical ingredients.

[0010] A variety of mechanisms have been proposed to reduce the undesired release of agrochemical ingredients, among them encapsulation of said product by a polymer. For instance EP 2 579 714 discloses the use of microencapsulated oils for controlling pesticide spray drift. Such methods typically do not address a further problem found in these microencapsulation systems, namely the challenges of encapsulating particularly volatile agrochemical ingredients. It is a further challenge that said microcapsules should comprise biodegradable components as defined by for instance the OECD 301 biodegradability in soil test, to avoid increased exposure of humans and wildlife to microplastics. Indeed, much of the prior art comprises capsules formed by the polymerization of isocyanates, e.g. WO 2010 / 093970, which is a known environmental toxin.

[0011] The prior art discloses the properties of the capsule shell, e.g. WO2018 / 210857 but does not disclose other aspects of the capsule, namely the constituents of the core that can be used to reduce the volatility of the agrochemical ingredient from the capsule into the external environment.

[0012] The aim of the present invention is thus to provide microcapsules encapsulating at least one agrochemical ingredient or agrochemical preparation that simultaneously reduce the volatility of the agrochemical ingredient or preparation and control its release rate over an extended time period.

[0013] Another aim of the present invention is to provide microcapsules encapsulating at least one agrochemical ingredient or agrochemical preparation, capable of assuring that the release will not be instantaneous upon application but rather extended over a desired time period.

[0014] Another aim of the present invention is to provide microcapsules encapsulating at least one agrochemical ingredient or agrochemical preparation, with improved biodegradability properties, allowing to reduce their environmental impact and ensure compliance with bans on the intentional use of microplastics. Therefore, the present invention relates to a solid cross-linked microcapsule encapsulating at least one agrochemical ingredient or agrochemical preparation, said microcapsule having a mean diameter from 0.5 pm to 50 pm, preferably from 1 pm to 30 pm, and more preferably from 3 pm to 30 pm, and said microcapsule comprising:

[0015] - a core consisting of a composition C1 comprising at least one agrochemical ingredient or agrochemical preparation, and

[0016] - a solid cross-linked polymer envelope totally encapsulating the core at its periphery, said solid cross-linked polymer envelope being made of a biodegradable cross-linked polymer, said polymer being an aliphatic nonaromatic polymer obtained by polymerizing one or several oligomer(s) or monomer(s), said polymer comprising preferably at least 20%, in particular at least 25%, and more preferably at least 30%, of ester groups by weight in comparison with the total weight of said polymer, and wherein the average thickness of said solid cross-linked polymer envelope is from 5% to 30% of the average diameter of said solid cross-linked microcapsule.

[0017] The present invention improves the existing microencapsulated formulations of agrochemical ingredients by providing a formulation that simultaneously reduces the volatility of the agrochemical ingredient or preparation, controls its release rate over an extended time period, assures that the release will not be instantaneous upon spray application but rather extended over a desired time period, and is furthermore encapsulated in a biodegradable shell and, if necessary, a biodegradable core additive. When applicable, the microcapsules of the invention have additionally proven equivalent or greater efficacy than their commercial references.

[0018] In the present application, the terms « microcapsules » and « capsules » are used indifferently.

[0019] The solid microcapsules have a core and a solid envelope (or shell) fully encapsulating the core on the periphery thereof, wherein the core consists of a composition C1 comprising at least one agrochemical ingredient or agrochemical preparation.

[0020] Preferably, these solid microcapsules are formed of a core containing agrochemical ingredient(s) or preparation (composition C1 ) and a solid envelope (or shell) (obtained from a specific polymer) fully encapsulating said core on the periphery thereof. As mentioned above, the microcapsules are solid cross-linked microcapsules.

[0021] The term "shell" refers to a solid cross-linked polymer envelope that has a roughly spherical shape. The function of a shell (or envelope), as used in a microcapsule, is to keep the encapsulated material found within the shell generally separate from the material outside of the microcapsule. The shell (or envelope) is diffusible so that under appropriate conditions it will allow diffusion into or out of the microcapsule to occur.

[0022] The term "core" of a microcapsule refers to the encapsulated composition located within the shell. The core of the microcapsules according to the invention is made of a composition C1 comprising at least one agrochemical ingredient or agrochemical preparation as active agent.

[0023] According to the present invention, the term “solid” refers to the non-liquid, cross-linked polymer.

[0024] According to the present invention, the term “cross-linked” refers to a polymer bond being formed between two or more oligomers.

[0025] The microcapsules according to the invention have a mean diameter as defined above, said diameter being measured by methods well known to the skilled person in the art, e.g. by a light scattering technique (for example using a Mastersizer 3000 equipped with a hydro SV measuring cell), or by image analysis of optical microscopy pictures, or by image analysis of electronic microscopy pictures.

[0026] Composition C1

[0027] Composition C1 comprises at least one agrochemical ingredient or agrochemical preparation as explained above. This composition C1 acts as carrier for the agrochemical ingredient(s), within the droplets formed during the method of the invention and in the solid capsules obtained.

[0028] According to the invention, the term “agrochemical ingredient” may also be named “agrochemical active product” or “agrochemical compound”.

[0029] According to the invention, the term “agrochemical preparation” may also be named “agrochemical composition”. This term may also refer to an agrochemical composition comprising at least one agrochemical ingredient as defined above.

[0030] According to an embodiment, composition C1 is monophasic i.e., it is the agrochemical ingredient(s) alone or it is a solution comprising the agrochemical ingredient(s) in solubilized form. In one embodiment, the agrochemical ingredient(s) is solubilized in composition

[0031] C1.

[0032] In this variant, composition C1 is typically composed of a solution of the agrochemical ingredient(s) in an aqueous solution or organic solvent, or a mixture of organic solvents, the agrochemical ingredient(s) being contained in a weight content of between 1 % to 99% relative to the total weight of composition C1. The agrochemical ingredient(s) may be contained in a weight content of between 5% to 95%, 10% to 90%, 20% to 80%, 30% to 70% or 40% to 60% relative to the total weight of composition C1.

[0033] In one embodiment, composition C1 consists of the agrochemical ingredient(s) or preparation.

[0034] In another embodiment of the invention, composition C1 is a biphasic composition, which means that the agrochemical ingredient(s) or agrochemical preparation is dispersed either in liquid form or in solid form in composition C1 and is not fully solubilized in said composition C1 .

[0035] According to an embodiment, the composition C1 further comprises a viscosifying agent and / or a biodegradable carrier oil.

[0036] This embodiment reduces the volatility of the agrochemical ingredient(s) or agrochemical preparation by encapsulating it in a polymer shell with a high cross-link density and may further include the formulation of a core capsule comprising a biodegradable oil and viscosifying agent that limits the diffusion of the agrochemical ingredient(s) or agrochemical preparation into the shell polymer.

[0037] According to an embodiment, the composition C1 further comprises a viscosifying agent.

[0038] According to a preferred embodiment, the composition C1 further comprises from 1% to 20%, preferably from 1% to 15%, and more preferably from 1% to 10%, by weight of a viscosifying agent relative to the total weight of said composition C1 .

[0039] According to the invention, the term “viscosifying agent” refers to a compound that increases the viscosity of the medium to which it is added, preferably obtaining a viscosity of at least 100 mPa.s, preferably of at least 1 ,000 mPa.s, even more preferably at least 2000 mPa.s and most preferably above 10,000 mPa.s, as determined at a shear rate of 10 s-1. Such agent is thus able to improve the viscosity of the composition C1 containing the agrochemical ingredient(s) or agrochemical preparation. A higher viscosity reduces the volatility of the agrochemical ingredient(s) or agrochemical preparation from the capsule by limiting the diffusion of the agrochemical ingredient(s) or agrochemical preparation into the polymer envelope as defined above.

[0040] Preferably, the viscosifying agent is selected from the group consisting of: fumed silica, clay, organic polymers such as hydrogenated vegetable oils, and hydrogels such as polysaccharides or hydrophilic silicates.

[0041] According to a preferred embodiment, the viscosifying agent is fumed silica.

[0042] According to an embodiment, the composition C1 further comprises a biodegradable carrier oil.

[0043] According to a preferred embodiment, the composition C1 further comprises from 5% to 40% by weight of a biodegradable carrier oil relative to the total weight of said composition C1 .

[0044] More preferably, the composition C1 comprises from 5% to 30% by weight of a biodegradable carrier oil relative to the total weight of said composition C1 .

[0045] According to the invention, the term “biodegradable carrier oil” refers to an oil in which the agrochemical ingredient(s) or preparation is miscible, which is furthermore biodegradable as defined by OECD Test 301 .

[0046] Preferably, the biodegradable carrier oil is selected from the polyester oils.

[0047] As preferred polyester oils, one may cite the one that are liquid at ambient temperature (from 20°C-50°C), and that have a boiling point above 60°C.

[0048] The biodegradable carrier oil according to the present invention has preferably a viscosity at room temperature comprised from 20 mPa.s to 5,000 mPa.s, preferably from 200 mPa.s to 5,000 mPa.s.

[0049] As preferred carrier oils, one may cite unsaturated polyol esters such as, byway of example, DEHYLUB® 4038 from EmeryOleo.

[0050] Alternatively, natural oils and natural lipid derivatives can be used as the biodegradable carrier oil, including but not limited to almond oil, castor oil, hydrogenated castor oil, fish oil, linseed oil, palm oil, hydrogenated palm oil, wheat germ oil, corn oil, cottonseed oil, hydrogenated cottonseed oil, sesame oil, soybean oil, hydrogenated soybean oil, butyl stearate, glyceryl monooleate, isopropyl myristate, oleic acid, and / or combinations thereof.

[0051] According to a preferred embodiment, the composition C1 comprises from 20% to 80%, in particular from 30% to 80%, preferably from 40% to 80%, more preferably from 50% to 80%, and even more preferably from 60% to 80%, by weight of agrochemical ingredient(s) or agrochemical preparation product relative to the total weight of said composition.

[0052] Agrochemical ingredient or agrochemical preparation as subject for encapsulation is understood encompassing for example biocides, herbicides, fungicides, insecticides, nematicides, acaricides, rodenticides, biocontrol agents (including semiochemicals, and natural extracts), biorationals, plant growth regulators, repellants, biostimulants, fertilizers, micronutrients, adjuvants, safeners for herbicides, synergists for insecticides, antitranspirants, fumigants and soil sterilizers, preservatives, or formulation ingredients like antioxidants.

[0053] Preferably, the agrochemical ingredient is selected from the group consisting of herbicides, insecticides, pheromones, bactericides, and fungicides.

[0054] According to an embodiment, the microcapsule according to the invention comprises a core wherein the composition C1 comprises an agrochemical ingredient as defined above, as well as a viscosifying agent as defined above, such as fumed silica, as well as a polyester oil as biodegradable carrier oil.

[0055] According to an embodiment, the agrochemical ingredient is chosen among the essential oils such as peppermint oil.

[0056] According to an embodiment, the microcapsule according to the invention comprises a core wherein the composition C1 comprises an agrochemical ingredient such as essential oils, and preferably peppermint oil, as well as a viscosifying agent as defined above, as well as a polyester oil as biodegradable carrier oil. Polymer envelope

[0057] In one embodiment, the above-mentioned solid microcapsules comprise a solid shell that is entirely composed of crosslinked polymer. This polymer may also be named copolymer or be a (co)polymer network.

[0058] The microcapsules according to the invention comprise a shell or envelope as defined above that is made of a biodegradable cross-linked polymer, said envelope being obtained by polymerizing one or several oligomer(s) or monomer(s), said envelope being thus made of an aliphatic nonaromatic polymer resulting from the polymerization of said oligomers or monomers.

[0059] According to a preferred embodiment, this polymer comprises at least 25%, preferably at least 30%, of ester groups, by weight in comparison to the total weight of said polymer.

[0060] In the invention, the term « monomer », « oligomer » or « polymer » designates any base unit adapted for the formation of a solid material via polymerization, either alone or in combination with other monomers or polymers. The term « polymer » also encompasses oligomers.

[0061] The average thickness of the polymer envelope as defined above is measured by optical microscopy, wherein a collection of capsules is observed through an optical microscope and the image is recorded digitally. Standard digital tools available to a person skilled in the art of microscopy such as Imaged can be utilized to determine the thickness of the polymer envelope based on the contrast between the envelope and core. A minimum of 10 and preferably a minimum of 20 microcapsules can be analyzed in this manner to obtain an average value.

[0062] Throughout the present application, biodegradability is defined herein as the ability to degrade in a natural medium such as defined in OECD standards: OECD 301 (Ready biodegradability), namely OECD 301 A (Dissolved Organic Carbon (DOC) Die-Away), OECD 301 B (CO2 Evolution), OECD 301 C (Modified MITI (I) test), OECD 301 D (Closed Bottle test), OECD 301 E (Modified OECD Screening), OECD 301 F (Manometric Respirometry test), or further in OECD 304A (Inherent Biodegradability in Soil), OECD 306 (Biodegradability in Seawater) and OECD 310 (Ready Biodegradability - CO2 in Sealed Vessels), and OECD NF T 51800 (Compostable products definition). The following examples of polymers may be mentioned:

[0063] The suitability of the microcapsule for encapsulation of the agrochemical ingredient(s) or preparation is connected to certain attributes of the capsule, such as its core composition and the chemistry of the shell. In particular, controlling the core viscosity by controlling the composition of the core enables an improved retention of the agrochemical ingredient(s) or preparation. Furthermore, the chemistry of the capsule shell also has an impact on the retention of the agrochemical ingredient(s) or preparation. In particular, the percentage of ester groups in the shell and the molecular weight of the spacers are parameters that may have an impact on the retention of the agrochemical ingredient(s) or preparation. The spacer is defined as the distance between the ester groups in the final polymer shell (or envelope).

[0064] According to an embodiment, the polymer envelope comprises an aliphatic nonaromatic (co)polymer network of one or more oligomer(s) or monomer(s) comprising at least 25% weight of ester groups, preferably at least 30% weight, in relation to the total weight of said polymer. The primary component of the network can be referred to as M1 (or oligomer M1 ) and the secondary component can be referred to as M2 (monomer or oligomer M2). The distinction between M1 and M2 is for example the molecular weight. Preferably, the molecular weight of M1 is from 1 ,500 to 10,000 g / mol and the molecular weight of M2 is from 50 to 1 ,500 g / mol.

[0065] According to a preferred embodiment, the aliphatic nonaromatic polymer of the solid cross-linked polymer envelope is obtained by polymerizing one or several oligomer(s) or monomer(s) M1 and M2, the molecular weight of M1 being from 1 ,500 to 10,000 g / mol and the molecular weight of M2 being from 50 to 1 ,500 g / mol, said oligomers M1 and M2 comprising preferably at least one reactive function selected from the group formed by acrylate, methacrylate, vinyl ether, N-vinyl ether, epoxy, siloxane, amine, lactone, phosphate and carboxylate functions.

[0066] Preferably, the shell (or envelope) chemistry is defined through the minimal percentage of ester groups in the shell, which has a high influence on the cross-linking density of said shell. It will be clear to a person skilled in the art that the selection of the oligomers and monomers that are contained in the envelope determines the value of the average molecular weight of the spacer between the cross-links (or ester groups). The spacer between the cross-links can be defined as a chain between two ester groups. To produce capsules comprising said polymer network in the shell, the raw materials can be selected using the fact that this value can be calculated by determining the average of the ratio of the molecular weight of the oligomer / (number of reactive function(s)-l ) % in the pre-polymenzed ohgomer(s) M1 and M2. The value can also be determined experimentally from the final polymerized solid envelope in the following manner: acid hydrolysis can be used to break down the ester bonds after which a chemical analysis of the molecular weight of the constituents between each ester bond can be performed using methods known to a person skilled in the art such as size exclusion chromatography (SEC) or TOF-SIMS. SEC may be carried out out with a Waters 510 HPLC pump equipped with three columns from Polymer Labs, Inc., having 5 pm bead size (two with MIXED-D and one 50 A pore sizes). THF can be used as the eluent. Such a measurement system is typically equipped with a Waters R401 differential refractometer as the detector. Typically the weight fraction distribution as a function of molecular weight can be determined, which provides a value for the distance between the ester bonds in the polymer envelope.

[0067] The reactive functions as mentioned above in M1 and / or M2 are preferably selected from the group formed by acrylate, methacrylate, vinyl ether, N-vinyl ether, epoxy, siloxane, amine, lactone, phosphate and carboxylate functions.

[0068] The influence of selection of pre-polymerized oligomers on the percentage of ester groups in the final solid polymerized shell also plays a role in the properties of the capsule and its performance. The selection of oligomers M1 and M2 can be optimized by tailoring the selection thereof to achieve a minimum of 25% weight of ester groups.

[0069] The percentage of ester groups in a polymerized shell is the ratio between the weight of ester groups present in the shell and the weight of total polymer shell material. One can determine this value from the pre-polymerized oligomers M1 and M2 with the following formula: where: the sum considers all oligomers irrespective of their type M1 or M2, fi is the number percentage of oligomer / in the shell material, riesteri is the sum of the number of ester groups and reactive functions that subsequently become an ester group after cross-linking within oligomer I, MWiis the molecular weight of oligomer I, and Mw ester is the molecular weight of an ester group.

[0070] Furthermore, the % ester groups can also be determined experimentally from the final polymerized solid envelope in the following manner: using solid nuclear magnetic resonance methods, by which the ester atoms have a specific resonant frequency, which can be compared to the resonant frequency of the atoms in a carbon-carbon bond through a ratio between the two, the ratio thereof thereby providing a percentage of the ester groups in the total molecular structure of the shell. In particular the peak observed using13C MAS NMR, at 180 ppm is characteristic of an ester bond, whereas a C-H bond is characterized by a peak at 30 ppm. Solid state13C MAS-NMR proton decoupling single-pulse spectra of polymers can be obtained with a Broker Avance DRX- 400 spectrometer using a magnetic field of 9.36 T and equipped with a multinuclear probe. The measurement conditions are preferably as follows: Minced samples are packed in 4 mm 0 zirconia rotors and spun at 10 KHz. The spectra are acquired at a frequency of 100.61 MHz, using a TT / 6 pulse width of 2.5 ps and a pulse space of 10 s to ensure full relaxation and to allow quantitative analysis from peak areas. Such methods are detailed in for instance Benitez, Jose & Heredia-Guerrero, Jose & Guzman-Puyol, Susana & Barthel, Markus & Dominguez, Eva & Heredia, Antonio. (2015). “Polyhydroxyester Films Obtained by Non-Catalyzed Melt-Polycondensation of Natural Occurring Fatty Polyhydroxyacids.” Frontiers in Materials. 2. 10.3389 / fmats.2015.00059.

[0071] Among the examples of such oligomers for M1 , the following compounds and mixtures thereof may be mentioned: the family of aliphatic esters and polyesters particularly comprising polyglycolides (PGAs), polylactides (PLAs), poly(lactide-co- glycolide) (PLGAs), poly(ortho esters) e.g. polycaprolactone (PCL), polydioxanone, polyethylene succinate), poly(butylene succinate) (PBS), polyethylene adipate), poly(butylene adipate), poly(ethylene sebacate), poly(valerolactone) (PVL), poly(decalactone), polyhydroxyvalerate, poly(beta-malic acid), poly-3- hydroxybutyrate (PHB), poly-3-hydroxy-butyrate-co-3-hydroxyvaldrate (P-3H B-3HV), poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P-3H B-4H B), poly-3- hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate (P-3HB-3HV-4HB), poly (3-hydroxyvalerate), poly(3-hydroxypropionate), poly (3-hydroxycaproate), poly (3- hydroxyoctanoate), poly(3-hydroxydecanoate), poly(3-hydroxyundecanoate), poly(3- hydroxydodecanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxy butyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxyheptanoate), poly(3- hydroxyhexanoate), poly(2-hydroxybutyrate), poly(3-hydroxybutyrate-co-4-hydroxy- butyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate- co-3-hydroxyhexanoate), poly(4-hydroxybutyrate), poly(4-hydroxybutyrate-co-2- hydroxybutyrate), poly(4-hydroxypropionate), poly(4-hydroxyvalerate), poly(5- hydroxybutyrate), poly(5-hydroxyvalerate), poly(6-hydroxyhexanoate), poly(alkylene alkanoate), poly(alkylene dicarboxylate), poly(butylene adipate, poly(butylene carbonate), poly(butylene pimelate), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(butylene succinate-co-carbonate), poly(butylene sebacate), poly(butylene succinate-co-lactate), polydiaxanone, polyethylene azelate), polyethylene carbonate), polyethylene decamethylate), polyethylene furanoate), polyethylene oxalate), polyethylene succinate), polyethylene succinate- co-adipate), polyethylene sebacate), polyethylene suberate), poly(hexamethylene sebacate), poly(glycolide-co-caprolactone), poly(lactide-co-epsilon-caprolactone), polymandelide, poly (B-malic acid), poly(propylene succinate), poly(tetramethylene carbonate), poly(trimethylene carbonate), poly(tetramethylene succinate)-co- (tetramethylene carbonate), poly(trimethylene adipate), poly(tetramethylene adipate), poly(tetramethyl glycolide), aliphatic poly(urethane) such as polycaprolactone, polycarbonate urethanes, aliphatic urethane diacrylate, aliphatic urethane methacrylate, aliphatic urethane triacrylate, non-isocyanate polyurethanes, poly(valerolactone), additionally carrying at least one reactive function selected from the group formed by acrylate, methacrylate, vinyl ether, N-vinyl ether, epoxy, siloxane, amine, lactone, phosphate and carboxylate functions.

[0072] Among the examples of oligomers for M2, the following compounds and mixtures thereof may be mentioned: diacrylates e.g. 1 ,6-hexanediol diacrylate, 1 ,6- hexanediol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, 1 ,9-nonanediol dimethacrylate, 1 ,4-butanediol dimethacrylate, 1 ,3- butanediol dimethacrylate, 1 ,10-decanediol dimethacrylate, bis(2-methacryloxyethyl) N,N'-1 ,9-nonylene biscarbamate, 1 ,4-butanediol diacrylate, 1 ,5-pentanediol dimethacrylate, allyl methacrylate, N,N'-methylenebisacrylamide, 2,2-bis[4-(2- hydroxy-3-methacryloxypropoxy)phenyl]propane, tetraethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, polyethylene glycol diglycidyl ether, N,N-diallylacrylamide or glycidyl methacrylate; multifunctional acrylates e.g. dipentaerythritol pentaacrylate, 1 ,1 ,1 - trimethylolpropane triacrylate, 1 ,1 ,1 -trimethylolpropane trimethacrylate, ethylenediamine tetramethacrylate, pentaerythritol triacrylate or pentaerythritol tetraacrylate; and acrylates also having another reactive function e.g. propargyl methacrylate, N-acryloxysuccinimide, N-(2-Hydroxypropyl) methacrylamide, N-(t- BOC-aminopropyl) methacrylamide, monoacryloxyethyl phosphate, acrylic anhydride, 2-(tert-butylamino) ethyl methacrylate, N,N-diallylacrylamide , N-ethoxy ethyl acrylates, propoxylated N- glyceryl triacrylate or glycidyl methacrylate or ethers and polyethers particularly comprising polyethylene glycols, additionally carrying at least one reactive function selected from the group formed by acrylate, methacrylate, vinyl ether, N-vinyl ether, epoxy, and amine functions and mixtures thereof.

[0073] According to a preferred embodiment, the solid cross-linked microcapsule according to the invention is devoid of surfactant. Preferably, neither the core nor the envelope comprises any surfactant.

[0074] According to a preferred embodiment, the solid cross-linked microcapsule according to the invention further comprises an anionic polyelectrolyte polymer, preferably a lignosulfonate. Preferably, said anionic polyelectrolyte polymer is in the envelope of the microcapsules. Said preferred embodiment improves the dispersion of microcapsules in a liquid slurry.

[0075] According to an embodiment, the present invention relates to a solid crosslinked microcapsule as defined above, wherein the solid cross-linked polymer envelope is formed through LIV polymerization.

[0076] The encapsulation systems in the prior art are based on either interfacial polymerization or coacervation, whereas the present invention preferably uses a double emulsion method that significantly reduces energy consumption and waste produced over the course of capsule production.

[0077] Preferably, the solid cross-linked microcapsule is prepared according to the specific process as explained hereafter.

[0078] The process for the preparation of a solid cross-linked microcapsule according to the invention may for example comprise the following steps: a) under stirring, adding a composition C1 comprising the agrochemical ingredient(s) or preparation to a polymeric composition C2, compositions C1 and C2 not being miscible with each other, C1 the composition C1 being as defined above, the viscosity of composition C2 being between 500 mPa.s and 100 000 mPa.s at 25°C, and preferably being higher than the viscosity of composition C1 , the composition C2 comprising:

[0079] - one or several oligomer(s) or monomer(s) M1 and M2 as defined above, and

[0080] - at least one photoinitiator or crosslinking catalyst, after which an emulsion (E1 ) is obtained comprising droplets of the composition C1 dispersed in the composition C2; b) under stirring, adding the emulsion (E1 ) to a composition C3, compositions C2 and C3 not being miscible with each other, the viscosity of composition C3 being between 500 mPa.s and 100 000 mPa.s at 25° C, and preferably being higher than the viscosity of emulsion (E1 ), after which a double emulsion (E2) is obtained comprising droplets dispersed in composition C3; c) applying shear to emulsion (E2), after which a double emulsion (E3) is obtained comprising droplets of controlled size dispersed in composition C3; and d) polymerizing composition C2, after which solid cross-linked microcapsules are obtained dispersed in composition C3.

[0081] At step a), the composition C1 is added to a crosslinkable polymeric composition C2, this step being conducted under stirring which means that composition C2 is kept under agitation typically mechanically whilst composition C1 is added, to emulsify the mixture of compositions C1 and C2.

[0082] Throughout step a), composition C1 is at a temperature of between 0°C and 100°C, preferably between 10°C and 80°C, and more preferably between 15°C and 60°C. Throughout step a), composition C2 is at a temperature of between 0°C and 100°C, preferably between 10°C and 80°C, and more preferably between 15°C and 60°C.

[0083] Under the conditions for addition at step a), compositions C1 and C2 are not miscible with each other, which means that the amount (by weight) of composition C1 capable of being solubilized in C2 is equal to or lower than 5 %, preferably lower than 1 %, and more preferably lower than 0.5 % relative to the total weight of composition C2, and that the amount (by weight) of composition C2 capable of being solubilized in composition C1 is equal to or lower than 5 %, preferably lower than 1 %, and more preferably lower than 0.5 % relative to the total weight of composition C1 .

[0084] Therefore, when composition C1 comes into contact with C2 under agitation, it is dispersed in the form of droplets called single droplets.

[0085] The immiscibility between compositions C1 and C2 also allows prevented migration of the agrochemical ingredient(s) or preparation of composition C1 towards composition C2. Composition C2 is stirred to form an emulsion comprising droplets of composition C1 dispersed in composition C2. This emulsion is also called a « single emulsion » or C1 -in-C2 emulsion.

[0086] To carry out step a), it is possible to use any type of mixer usually used to form emulsions e.g. a mechanical blade mixer, static emulsifier, ultrasonic homogenizer, membrane homogenizer, high-pressure homogenizer, colloidal mixer, high-shear disperser or high-speed homogenizer.

[0087] The volume fraction of C1 in C2 can vary from 0.1 to 0.6 to control the thickness of the shell of the capsules obtained on completion of the method.

[0088] In one embodiment, the ratio between the volume of composition C1 and the volume of composition C2 varies between 1 :10 and 10:1. Preferably, this ratio is between 1 :3 and 5:1 , more preferably betweenl :3 and 3:1 .

[0089] Preferably, the viscosity of composition C2 at 25° C is between 1 000 mPa.s and 300 000 mPa.s, more preferably between 25 000 mPa.s and 250 000 mPa.s, for example it is between 50 000 mPa.s and 25 000 mPa.s.

[0090] Preferably, the viscosity of composition C2 is higher than the viscosity of composition C1.

[0091] Viscosity is measured using a Haake Rheostress™ 600 rheometer equipped with cone of diameter 60 mm having 2-degree angle, and a temperature control cell set at 25° C. The value of viscosity is determined at a shear rate of 10 s-1.

[0092] In this embodiment, the destabilizing kinetics of the droplets of emulsion (E1 ) are significantly slow, allowing the shell of the microcapsules to be polymerized at step d) before the emulsion become unstable. Polymerization, once completed, then provides thermodynamic stabilization. Therefore, the relatively high viscosity of composition C2 ensures the stability of emulsion (E1 ) obtained after step a).

[0093] Composition C2 contains at least one monomer or oligomer such as defined below, and at least one photoinitiator or crosslinking catalyst, making the composition crosslinkable.

[0094] In one embodiment, composition C2 comprises from 50% to 99% by weight of monomer or polymer such as defined below, or a mixture of monomers and polymers such as defined below, relative to the total weight of composition C2. In one embodiment, composition C2 comprises from 0.1 % to 5% by weight of photoinitiator or a mixture of photoinitiators, relative to the total weight of composition 02.

[0095] By « photoinitiator » it is meant a compound capable of fragmenting under the effect of light radiation.

[0096] The photoinitiators which can be used in the present invention are known in the art and are described for example in "Les photoinitiateurs dans la reticulation des revetements" (Photoinitiators in the crosslinking of coatings) G. Li Bassi, Double Liaison - Chimie des Peintures, N°361 , November 1985, p.34-41 ; "Applications industrielles de la polymerisation photoinduite" (Industrial applications of photoinduced polymerization) Henri Strub, LActualite Chimique, February 2000, p.5- 13; and "Photopolymeres : considerations theoriques et reaction de prise" (Photopolymers: theoretical considerations and curing reaction), Marc, J.M. Abadie, Double Liaison - Chimie des Peintures, N°435-436, 1992, p.28-34.

[0097] At step b) of the method of the invention, a second emulsion (E2) is prepared.

[0098] The second emulsion is composed of a dispersion of droplets of the first emulsion in a composition C3 immiscible with C2, created through the dropwise addition of emulsion (E1 ) to C3 under stirring.

[0099] Throughout step b), emulsion (E1 ) is at a temperature of between 15°C and 60°C. Throughout step b), composition C3 is at a temperature of between 15°C and 60°C.

[0100] Under the conditions for addition at step b), compositions C2 and C3 are not miscible with each other, which means that the amount (by weight) of composition C2 capable of being solubilized in composition C3 is equal to or lower than 5%, preferably lower than 1%, and more preferably lower than 0.5% relative to the total weight of composition C3, and that the amount (by weight) of composition C3 capable of being solubilized in composition C2 is equal to or lower than 5%, preferably lower than 1 %, and more preferably lower than 0.5% relative to the total weight of composition C2.

[0101] Therefore, when emulsion (E1 ) comes into contact with composition C3 under agitation, it is dispersed in the form of droplets called double droplets, the dispersion of these droplets of emulsion (E1 ) in the C3 continuous phase being called emulsion (E2).

[0102] Typically, a double droplet formed at step b) corresponds to a single droplet of composition C1 such as described above, surrounded by a shell of composition C2 which fully encapsulates said single droplet. The double droplet formed at step b) may also comprise at least two single droplets of composition C1 , said single droplets being surrounded by a shell of composition C2 which fully encapsulates said single droplets.

[0103] Therefore, said double droplets comprise a core composed of one or more single droplets of composition C1 , and a layer of composition C2 surrounding said core.

[0104] The resulting emulsion (E2) is generally a polydisperse double emulsion (C1 -in C2-in C3 emulsion, or C1 / C2 / C3 emulsion), which means that the double droplets do not have a distinct size distribution in emulsion (E2).

[0105] The immiscibility between compositions C2 and C3 allows prevented mixing between the layer of composition C2 and composition C3, and thereby ensures the stability of emulsion (E2).

[0106] The immiscibility between compositions C2 and C3 also allows prevented migration of the water-soluble substance of C1 from the core of the droplets towards composition C3.

[0107] T o implement step b), it is possible to use any type of mixer usually used to form emulsions, e.g. a mechanical blade mixer, static emulsifier, ultrasonic homogenizer, membrane homogenizer, high-pressure homogenizer, colloidal mixer, high-shear disperser or high-speed homogenizer.

[0108] The continuous phase C3 may be defined by the selection of a material with optimized viscosity parameters, according to WO2022 / 1 17681 , that is incorporated herein by reference.

[0109] In one embodiment, the viscosity of composition C3 at 25°C is higher than the viscosity of emulsion (E1 ) at 25°C.

[0110] In the invention, the viscosity of composition C3 at 25°C is between 500 mPa.s and 100 000 mPa.s.

[0111] Preferably, the viscosity of composition C3 at 25°C is between 3 000 mPa.s and 100 000 mPa.s, more preferably between 5 000 mPa.s and 80 000 mPa.s, e.g. between 7 000 mPa.s and 70 000 mPa.s.

[0112] In this embodiment, given the very high viscosity of the continuous phase formed by composition C3, the rate of destabilization of the double droplets of emulsion (E2) is significantly slow compared with the duration of the method of the invention, which therefore affords kinetic stabilization of emulsion (E2) and then of (E3) until polymerization of the shell of the capsules is completed. Once polymerized, the capsules are thermodynamically stable. Therefore, the very high viscosity of composition C3 ensures the stability of emulsion (E2) obtained after step b).

[0113] Low surface tension between C3 and the first emulsion as well as high viscosity of the system advantageously allow ensured kinetic stability of the double emulsion (E2), preventing dephasing thereof throughout the production time.

[0114] Preferably, the interfacial tension between compositions C2 and C3 is low. This low interfacial tension between compositions C2 and C3 also advantageously allows ensured stability of emulsion (E2) obtained after step b).

[0115] The volume fraction of the first emulsion in C3 can be varied between 0.05 and 0.5 first to improve production yield and secondly to vary the mean diameter of the capsules. On completion of this step, the size distribution of the second emulsion is relatively wide.

[0116] In one embodiment, the ratio between the volume of emulsion (E1 ) and the volume of composition C3 varies from 1 :10 to 10:1. Preferably, this ratio is from 1 :9 to 3:1 , more preferably from 1 :9 to 1 :1 .

[0117] In one embodiment, the composition C3 further comprises one or several water- soluble anionic polyelectrolyte polymer(s). The composition C3 may comprise from 0.01 to 15 mass% of said polymer, preferably from 0.05 to 10 mass% of said polymer, more preferably from 0.1 to 10% of said polymer. In one embodiment, said anionic polyelectrolyte polymer is a lignosulfonate.

[0118] At step c) of the method of the invention, the size of the droplets of the second emulsion (E2) is refined.

[0119] At this step, controlled homogeneous shear can be applied to emulsion (E2), said rate of applied shear being between 1 10 s1and 100 000 s-1.

[0120] In one embodiment, the polydisperse double droplets obtained at step b) are subjected to size refining whereby they undergo shear capable of fragmenting them into new double droplets of controlled and homogeneous diameter. Preferably, this fragmentation step is performed using a high-shear cell of Couette type following a method described in patent application EP 15 306 428.2.

[0121] In one embodiment, at step c), the second emulsion (E2) obtained after step b), composed of polydisperse double droplets dispersed in a continuous phase, is subjected to shear in a mixer which applies controlled, homogeneous shear.

[0122] Therefore, in this embodiment, at step c) controlled, homogeneous shear is applied to emulsion (E2), said applied shear rate being between 1 000 s-1and 100 000 s’1. In this embodiment, in a mixer, the shear rate is said to be controlled and homogeneous, independently of time length, when it reaches a maximum value that is the same for all the parts of the emulsion at a given instant which can vary from one point of the emulsion to another. The exact configuration of the mixer is not essential according to the invention, provided that the whole emulsion has been subjected to the same maximum shear on leaving this device. Mixers suitable for performing step c) are notably described in US 5 938 581 .

[0123] The second emulsion can be subjected to controlled, homogeneous shear when it circulates through a cell formed by:

[0124] - two concentric rotating cylinders (also called Couette-type mixer);

[0125] - two parallel rotating discs; or

[0126] - two parallel oscillating plates.

[0127] In this embodiment, the shear rate applied to the second emulsion is between 1 000 s-1and 100 000 s’1, preferably between 1 000 s-1and 50 000 s’1, and more preferably between 2 000 s-1and 20 000 s’1.

[0128] In this embodiment, at step c), the second emulsion is placed in the mixer and subjected to shear resulting in the formation of the third emulsion. The third emulsion (E3) is chemically the same as the second emulsion (E2) but is composed of monodisperse double droplets whereas emulsion (E2) is composed of polydisperse double droplets. The third emulsion (E3) is typically composed of a dispersion of double droplets comprising a core formed of one or more droplets of composition C1 and of a layer of composition C2 encapsulating said core, said double droplets being dispersed in composition C3.

[0129] The difference between the second emulsion and the third emulsion is the size variance of the double droplets: the droplets of the second emulsion are polydisperse in size whereas the droplets of the third emulsion are monodisperse by means of the fragmentation mechanism described above.

[0130] Preferably, in this embodiment, the second emulsion is added continuously to the mixer, which means that the amount of double emulsion (E2) fed into the mixer is the same as the amount of third emulsion (E3) leaving the mixer.

[0131] Since the size of the droplets of emulsion (E3) essentially corresponds to the size of the droplets of the solid microcapsules after polymerization, it is possible to adjust the size of the microcapsules and the thickness of the shell by adjusting the shear rate at step c), with strong correlation between the reduction in size of the droplets and the increase in shear rate. This makes it possible to adjust the resulting dimensions of the microcapsules by varying the shear rate applied at step c). In one preferred embodiment, the mixer used at step c) is a mixer of Couette type comprising two concentric cylinders, an outer cylinder of inner radius Roand an inner cylinder of outer radius R, the outer cylinder being fixed and the inner cylinder rotating at an angular velocity co.

[0132] A mixer of Couette type adapted for the method of the invention can be supplied by T.S.R. France.

[0133] In one embodiment, the angular velocity co of the rotating inner cylinder of the Couette-type mixer is equal to or higher than 30 rad.s-1.

[0134] For example, the angular velocity co of the inner rotating cylinder of the Couette- type mixer is about 70 rad.s-1.

[0135] The dimensions of the outer fixed cylinder of the Couette-type mixer can be chosen to modulate the space (d = Ro- Ri) between the inner rotating cylinder and outer fixed cylinder.

[0136] In one embodiment, the space (d = Ro- Ri) between the two concentric cylinders of the Couette-type mixer is between 50 pm and 1 000 pm, preferably between 100 pm and 500 pm, for example between 200 pm and 400 pm.

[0137] For example, the distance d between the two concentric cylinders is 100 pm.

[0138] In this embodiment, at step c), the second emulsion is fed into the mixer typically via a pump and is directed towards the space between the two concentric cylinders, the outer cylinder being fixed and the inner cylinder rotating at an angular velocity co.

[0139] When the double emulsion reaches the space between the two cylinders, the shear rate applied to said emulsion is given by the following equation: where:

[0140] - co is the angular velocity of the inner rotating cylinder,

[0141] - Ro is the inner radius of the outer fixed cylinder, and

[0142] - Ri is the outer radius of the inner rotating cylinder.

[0143] In another embodiment, when the viscosity of composition C3 is higher than 2 000 mPa.s at 25°C, at step c) a shear rate of less than 1 000 s-1is applied to emulsion (E2).

[0144] In this embodiment, the fragmentation step c) can be performed using any type of mixer usually used to form emulsions at a shear rate lower than 1 000 s-1, in which case the viscosity of composition C3 is higher than 2 000 mPa.s, namely under conditions such as those described in patent application FR 16 61787. The geometric characteristics of the double droplets formed on completion of this step will dictate those of the future capsules.

[0145] In this embodiment, at step c), emulsion (E2) formed of polydisperse droplets dispersed in a continuous phase, is subjected to shear e.g. in a mixer at a low shear rate, namely lower than 1 000 s-1.

[0146] In this embodiment, the shear rate applied at step c) is from 10 s-1to 1 000 s-1for example.

[0147] Preferably, the shear rate applied at step c) is strictly lower than 1 000 s-1.

[0148] In this embodiment, the droplets of emulsion (E2) can only be efficiently fragmented into fine, monodisperse droplets of emulsion (E3) if a high shear stress is applied thereto.

[0149] The shear stress c applied to a droplet of emulsion (E2) is defined as the tangential force per unit surface area of the droplet resulting from the macroscopic shear applied to the emulsion when mixed at step d).

[0150] The shear stress c (expressed in Pa), viscosity of composition C3 n (expressed in Pa s) and shear rate y (expressed in s-1) applied to emulsion (E2) when mixed at step d) are related by the following equation:

[0151] <J = r|y

[0152] Therefore, in this embodiment, the high viscosity of composition C3 allows the application of very high shear stress to the droplets of emulsion (E2) in the mixer, even if the shear rate is low and shear is non-homogeneous.

[0153] To implement step c) in this embodiment, it is possible to use any type of mixer usually used to form emulsions, e.g. a mechanical blade mixer, static emulsifier, ultrasonic homogenizer, membrane homogenizer, high-pressure homogenizer, colloidal mixer, high-shear disperser or high-speed homogenizer.

[0154] In one preferred embodiment, a simple emulsifier is used such as a mechanical paddle blade mixer or static emulsifier to carry out step c). This is possible since this embodiment does not require either controlled shear or shear greater than 1 000 s-1.

[0155] At step d) of the method of the invention, the shell of the solid microcapsules of the invention is crosslinked and hence formed.

[0156] This step allows both expected performance levels to be reached for capsule retention and ensured thermodynamic stability thereof, by definitively preventing any destabilization mechanism such as coalescence or maturation.

[0157] In one embodiment, when composition C2 comprises a photoinitiator, step d) is a photopolymerization step whereby emulsion (E3) is exposed to a light source able to initiate photopolymerization of composition C2, in particular to a UV light source preferably emitting in the wavelength range of between 100 nm and 400 nm, and in particular for a time of less than 15 minutes.

[0158] In this embodiment, at step d) emulsion (E3) is subjected to photopolymerization, which will allow photopolymerization of composition C2. This step will allow the obtaining of microcapsules encapsulating the water-soluble substance such as defined above.

[0159] In one embodiment, at step d) emulsion (E3) is exposed to a light source able to initiate photopolymerization of composition C2.

[0160] Preferably, the light source is a UV light source.

[0161] In one embodiment, the UV light source emits in the wavelength range of between 100 nm and 400 nm.

[0162] In one embodiment, emulsion (E3) is exposed to a light source for a time of less than 15 minutes, preferably for 5 to 10 minutes.

[0163] At step d), the shell of the above-mentioned double droplets composed of photo- crosslinkable composition C2, is crosslinked and thereby converted to a viscoelastic polymeric shell encapsulating and protecting the water-soluble substance against release thereof in the absence of mechanical triggering.

[0164] In another embodiment, when composition C2 does not comprise a photoinitiator, step d) is a polymerization step without exposure to a light source, the length of time of this polymerization step d) preferably being between 8 hours and 100 hours and / or this step d) is conducted at a temperature of between 20°C and 80°C.

[0165] In this embodiment, polymerization is initiated for example by exposure to heat (thermal initiation) or by mere contacting together of the monomers, polymers and reticulating agents, or with a catalyst. Polymerization time is then generally longer than several hours.

[0166] Preferably polymerization step d) of composition C2 is carried out for a time of between 8 hours and 100 hours, at a temperature of between 20°C and 80°C.

[0167] The composition obtained after step d), comprising solid microcapsules dispersed in composition C3, is ready for use and can be used without any additional post-treatment step of the capsules being required.

[0168] The present invention also relates to formulations comprising at least one solid cross-linked microcapsule as defined above.

[0169] These formulations are advantageous in that they are stable. These formulations may also include to plant health products comprising at least one solid cross-linked microcapsule as defined above.

[0170] The present invention also relates to the use of a solid cross-linked microcapsule as defined above, for reducing the volatility of the agrochemical ingredient(s) or preparation.

[0171] The present invention also relates to a method for reducing the volatility of the agrochemical ingredient(s) or preparation, comprising the encapsulation of the agrochemical ingredient(s) or preparation into a solid cross-linked microcapsule as defined above.

[0172] According to an embodiment, in the method according to the invention, the release rate of the agrochemical ingredient(s) or preparation is characterized by an exponential decay function N(t) = Noe~kt, where the value of k varies from 0.6 to 1 .3 for t=1 and from 0.3 to 0.7 for values of t>1 , where t is measured in units of days, k is the rate of exponential decay and Nois the initial amount of the agrochemical ingredient(s) or preparation.

[0173] In the case of the agrochemical ingredient being a pheromone, preferably the value of k falls between 2 and 3 at t=1 and 0.0005 and 0.0015 from t=1 to t=90. This may alternatively be described as release rate is between 5-10% on the first day and below 1 % per day over 90 days.

[0174] In the case of the agrochemical ingredient being an herbicide, preferably the value of k falls between 0.6 and 1.3 at t=1 day and 0.02-0.06 at t>1. This may alternatively be described as a release rate that is between 30-50% on the first day and between 3-5% over the course of 1 -2 weeks.

[0175] In the case of the agrochemical ingredient being an insecticide, preferably the value of k falls between 0.05 and 0.1 for a crop protecting agent that is an insecticide (alternatively) preferably wherein the composition C1 contains an insecticide and the release rate is between 30-50% on the first day and below 1 % per day over 90 days

[0176] In the case of a biodegradable capsule, preferably the value of k arising purely from biodegradability is 0.15-0.2 in water - particularly important in the case of long- lasting capsules wherein the active liberation is a second order function and the value of k has a higher degree of complexity.

[0177] The determination of release kinetics is described extensively in the scientific literature, and is known to a person skilled in the art. By way of example, Fernanda V. Leimann, Odinei H. Gongalves, Ricardo A.F. Machado, Ariovaldo Bolzan, “Antimicrobial activity of microencapsulated lemongrass essential oil and the effect of experimental parameters on microcapsules size and morphology,” Materials Science and Engineering: C, Volume 29, Issue 2,2009, Pages 430-436, describes the measurement of retained encapsulated ingredient in a capsule as follows: A hydrodistillation apparatus (Clevenger) can be used to evaluate the active ingredient release from the microcapsules. The sample is filtered and washed three times with distilled water and one time with ethanol to remove any not encapsulated agrochemical active. The agrochemical active was collected from the apparatus at intervals of time. The released percentage was determined using the following equation: where m~ is the mass accumulated at the end of extraction and mtis the mass accumulated in the respective interval of time. released oil (%) = (mt* 100) / m°°

[0178] Gas chromatography / mass spectrometry analysis can then performed to determine the value of mtat a given time. Agrochemical active composition can be determined using a Varian CP-3800 gas-chromatograph equipped with a CP-Sil 8 CB Low Bleed / MS (30 mx0.25 mm) column using the following equipment conditions:, injector temperature at 250 °C; Helium as carrier gas (flow rate of 1 ml / min); oven temperature initially at 50 °C and then raised to 240 °C at 3 °C / min. Quantification was computed as the percentage contribution of each compound to the total amount present. EO constituents were then analyzed by Mass Spectrometry — MS (ion trap temperature at220 °C; manifold temperature at 80 °C, transfer line temperature at240 °C). The MS fragmentation patternwas checked bymatching theMSfragmentation patterns with NIST mass spectra libraries. An accelerated version of said test can be performed by elevating the storage conditions of the microcapsules from RT to 40 °C.

[0179] Said release kinetics are dictated by the physicochemical properties of the capsule shell and core. In particular, the capsule shell properties such as degree of polymerization, cross-linking density, porosity and other potential parameters play a significant role in the capsule release kinetics. A higher degree of polymerization(<95%), higher cross-linking density and lower porosity results in a slower release of the active from the capsule. Furthermore, the capsule core may contain viscosifying agents that further reduce the rate of release of the agrochemical active from the capsule. Furthermore, the rate of biodegradation, which is dependent upon microbes to which the capsules are exposed, will increase the rate of release of the agrochemical active through the formation of pores in the capsule over the course of biodegradation. This must be accounted for in field settings where the conditions of release are not identical to those of in vitro tests.

[0180] The present invention also relates to a method for treating a plant, and / or soil and / or undesirable pest and / or weed and / or water surface comprising the application onto said plant and / or soil and / or undesirable pest and / or weed and / or water surface of a formulation or plant health product as defined above, with the aim of protecting plant against pest and / or enhancing plant nutrition and / or regulating plant growth. Among the methods for treatment application are included spraying in ground or aerial application, drilling, spreading, fumigation, chemigation, fogging, and preferably spraying with existing equipment or emerging technology like for instance drones.

[0181] When applicable, the present invention also relates to a method using compositions comprising said microcapsules containing agrochemical ingredient(s) or agrochemical preparation for treating environment and / or green spaces (including turf for sports and gulf) and / or professional-public building and / or home and / or garden with the aim of pest control or vegetation management or hygiene.

[0182] The capsules of the invention contain the agrochemical ingredient(s) or preparation and are suitable for the development of stable agrochemical formulations. Therefore, a further aspect of the invention is a formulation containing the microcapsules disclosed herein. Said formulation may comprise the microcapsules of the invention and at least one additive, for example, an agriculturally acceptable carrier that can be solid or liquid. The formulations may also contain one or more components to help improve the physical properties of the formulation. Any type of existing formulation containing capsules is suitable for the purposes of the present invention. For example, the formulation can be one selected from the group consisting of aqueous capsule suspensions (CS), and mixtures of CS formulations with other formulation types, for example, mixtures of CS formulations with aqueous suspension concentrates (EW) to form ZC formulations, or mixtures with oil-in-water emulsions to form ZW formulations, or mixtures with suspoemulsions (SE) to form ZE formulations. The previous is a non-limitative list of formulation types defined in Catalogue of pesticide formulation types and international coding, Croplife Technical Monograph n°2, 7thEdition, Revised March 2017. Other formulation types including capsules may also be suitable.

[0183] A Capsule Suspension (CS) according to the present application is a stable suspension of capsules in a fluid, normally intended for dilution with water before use. A ZC formulation according to the present application is a material comprising a suspension of fine particles of an active ingredient, combined with a suspension of the microcapsules of the invention in an aqueous phase together with suitable additives. A ZW formulation according to the present application is a material comprising an emulsion of fine droplets of an active ingredient in the form of the combination of a suspension of the microcapsules of the invention in an aqueous phase together with suitable additives. A ZE formulation according to the present application is a material comprising an emulsion of fine droplets of an active ingredient and a suspension of fine particles of the microcapsules of the invention in an aqueous phase, together with suitable additives.

[0184] It is a further aspect of the invention a method for the control of weeds or pest comprising treatment, with an effective amount of the microcapsules of the invention comprising the agrochemical ingredient(s) or preparation, with the locus (or the future expected locus) of said weeds or pest.

[0185] It is a further aspect of the invention a method for the enhancing nutrition or regulating growth of crop comprising treating with an effective amount of the microcapsules of the invention comprising the agrochemical ingredient(s) or preparation with the locus (or the future expected locus) of said crop.

[0186] As used herein, the terms “control” or “controlling” or “combatting” refer to preventing disease or the growth of unwanted plants, protecting plants from disease, delaying the onset of disease, and killing, or to reducing the deleterious effects of the disease, or to killing or to reducing growth of unwanted plants.

[0187] As used herein, the term “effective amount” refers to an amount of the microcapsules of the invention which is sufficient for controlling weeds or pest on the locus of crop plants, including pasture, and does not cause any significant damage to the treated crop plants or pasture or which is sufficient to enhance crops nutrition or regulate its growth.

[0188] As used herein the term “plant” or “crop” or “crop plants” includes reference to whole plants, plant organs (e.g. leaves, stems, twigs, roots, trunks, limbs, shoots, fruits etc.), plant cells, or plant seeds, which have industrial interest, including grasslands and pastures, such as for example plants destined to human consumption, animal consumption or other industrial uses or ornamental uses. This term also encompasses crops such as fruits. The term “plant” may also include the propagation material thereof, which may include all the generative parts of the plant such as seeds and vegetative plant material such as cuttings and tubers, which can be used for the multiplication of the plant. It may also include spores, corms, bulbs, rhizomes, sprouts basal shoots, stolons, and buds and other parts of plants, including seedlings and young plants, which are to be transplanted after germination or after emergence from soil. Crops according to the present invention include rangelands, grass pastures, forestry, as well as non-crop land and rights-of-way sites such as around industrial and military installations, railways, airports, under powerlines and along pipelines. As used herein, the term “crop” includes plants which have been modified by breeding, mutagenesis or genetic engineering. Genetically modified plants are plants in which their genetic material has been modified by the use of recombinant DNA techniques. Typically, one or more genes have been integrated into the genetic material of such a plant in order to improve certain properties of the plant.

[0189] As used herein, the term “locus” includes a habitat, breeding ground, plant, propagation material, soil, area, material or environment in which undesired plants or weeds are growing or may grow.

[0190] As used herein, the phrase “agriculturally acceptable carrier” means carriers that are known and accepted in the art for the formation of formulations for agricultural or horticultural use, preferably approved by the regulator for use in agriculture. Agriculturally acceptable carriers can be solid or liquid (solvents).

[0191] As used herein, the term “tank mix” or “tank mixture” means any dilution of a formulation before application in the field. Formulations are typically sold as concentrates that require dilution in water before application.

[0192] As used herein, the term “adjuvant” is used to designate components that are added to the tank-mix to improve the biological performance or spray properties before application on the field. As compatibility agents, adjuvants typically improve the miscibility of the formulation in water or the dispersibility, as drift retardants they can reduce the fine droplets fractions. However, most adjuvants enhance wettability of crops or weeds or enhance penetration of actives and related features like rainfastness or systemicity. Some formulations can incorporate and adjuvant, the so called “built-in adjuvants”.

[0193] The present invention is also directed to tank mixtures comprising a formulation of the invention diluted in a liquid carrier, usually water. Said tank mixtures may optionally comprise other agrochemical products like crop protection agents, fertilizers or adjuvants.

[0194] The present invention is also directed to ready-to-use products comprising a formulation of the invention that can be directly applied for the application treatment.

[0195] The formulations containing the microcapsules of the invention can be prepared following known methods, e.g., by mixing the microcapsules with appropriate additional components (e.g., dispersing agents, wetting agents, carriers). In addition to liquid or solid carriers, the formulations comprising the microcapsules of the invention may comprise other usual additives known in the field of agrochemistry, including for example, surfactants (or surface-active substances) for various functions, crystallization inhibitors, hydrotropes, viscosity modifiers, suspending agents, dyes, antioxidants, anti-foaming agents, light absorbers, mixing auxiliaries, antifoams, complexing agents, pH-modifying substances and buffers, corrosion inhibitors, fragrances, wetting agents, penetration enhancers, spreaders, stickers, micronutrients, plasticizers, glidants, lubricants, dispersants, thickeners, antifreezes, microbiocides, and liquid and solid fertilizers.

[0196] The microcapsules of the invention can be formulated alone or in mixtures comprising further active ingredients in addition to the agrochemical ingredient(s) as defined above. Alternatively, the formulation of the invention may comprise the agrochemical ingredient(s) or agrochemical preparation as only active ingredient and then be tank-mixed with further actives ingredients. Thus, the formulations of the invention may comprise the microcapsules containing the agrochemical ingredient(s) or preparation as described herein and at least one additional agrochemical active ingredient or be tanked mixed with said at least one additional agrochemical active ingredient. Said at least one additional agrochemical active ingredient can be preferentially chosen from crop protection agents, i.e. herbicides, fungicides, or insecticides.

[0197] The term “a” or “an” as used herein includes the singular and the plural, unless specifically stated otherwise. Therefore, the terms “a,” “an” or “at least one” can be used interchangeably in this application.

[0198] For purposes of better understanding the present teachings and in no way limiting the scope of the teachings, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. In this regard, used of the term “about” herein specifically includes ±5% from the indicated values in the range. In addition, the endpoints of all ranges directed to the same component or property herein are inclusive of the endpoints, are independently combinable, and include all intermediate points and ranges.

[0199] The expressions « between ... and ... », « from ... to ... » and « ranging from ... to ... » are to be construed as including the limits unless specified otherwise.

[0200] EXAMPLES

[0201] Example 1 : Preparation of microcapsules with decanol

[0202] The microcapsules according to the invention have been formulated by incorporating a rheological agent. The comparative example (Comp.4) has been formulated without a rheological agent.

[0203] A mechanical stirrer (Ika Eurostar 20) equipped with a deflocculating stirring propeller is used to carry out all the stirring steps.

[0204] Step a): Creation of the Core of the Capsules (Dispersion of Particles - Composition C1)

[0205] Decanol 65%

[0206] Rheological agent 0-8%

[0207] Biodegradable carrier oil - (Priolube 1847) 27-31%

[0208] The core of the capsule is obtained by mixing the above components at RT until homogeneous, thereby obtaining C1 . Step b): Preparation of the shell composition

[0209] Shell composition:

[0210] M1 : aliphatic nonaromatic glycerol-modified polyester oligomer with acrylate terminal groups polyester comprising less than 3% of nitrogen by weight. 79%

[0211] M2: tri-acrylated monomer. 20%

[0212] Darocur 1173. 1 %

[0213] The shell of the capsule is prepared by mixing the above components at RT until homogeneous, thereby obtaining C2.

[0214] The composition of the core C1 is added at RT to the composition of the shell C2 with a mixing rate of 100 rpm to produce the first emulsion E1. The ratio of the weight of the shell to the weight of the core is 40 / 60.

[0215] Step c): Preparation of the Second Emulsion (E2)

[0216] Composition C3, the continuous phase, is produced from 8% sodium alginate, and 92% water. The composition C3 is stirred at 2,000 rpm until complete homogenization.

[0217] The first emulsion E1 is then added to the composition C3, which is then stirred at 2,000 rpm for 2 minutes at RT to obtain the second emulsion E2, at a ratio of E1 :C3 of 10:90.

[0218] Step d): Reticulation of the Capsule Envelope

[0219] The second emulsion (E2) obtained in the previous step is irradiated for 2 minutes with the aid of a LIV light source (Dymax LightBox ECE 2000) having a maximum light intensity of 1 W / cm2at a waveform length of 365 nm.

[0220] The microcapsules were separated from their continuous phase by centrifugation at 2000 G for over 3 cycles for a total of 20 min. Example 2: Encapsulation efficiency for the microcapsules of example 1

[0221] The encapsulation efficiency for the microcapsules of example 1 is shown to be improved by the use of a rheological agent, as shown by the higher % of core / shell structure particles, and reduction of janus particles. The results are described in Table 1.

[0222] Table 1. Encapsulation efficiency of the microcaspules

[0223] The quantity of retained decanol as shown in the Table.2 below was performed through thermogravimetric analysis (TGA), a Texas Instruments TGA Q5000 Automatic Sample Processor. The slurry of microcapsules was placed in a silicon mold at ambient temperature. Measurements of the slurry were taken at T=0, T=3 days, T= 7 days and T=14 days at room temperature. 10g of the microcapsule slurry are used for each measurement. The sample is exposed to a temperature ramp 0 to 600°C. The boiling temperature of decanol is 230°C. The % weight loss at T=0 at this temperature provides the baseline quantity of decanol in the microcapsule slurry.

[0224] The % weight loss at T=X provides an indication of the encapsulation efficacy, which can then be subtracted from 100 to determine the residual decanol in the capsules.

[0225] Table 2. It can be observed that after 3 days, the capsules containing a rheological agent have a higher residual decanol content than the capsules produced without a rheological agent.

[0226] In the absence of the modified core (viscose biodegradable carrier oil, preferably in combination with a rheological modifier), the encapsulation efficiency diminishes significantly, resulting in an undesirably low percentage of core-shell structured microcapsules and a high proportion of either janus particles or unencapsulated active.

[0227] Example 3: Improved encapsulability of phytosanitary actives through use of rheological agent

[0228] Other microcapsules were prepared by applying the same protocol as in example 1 with other actives, as shown in below Tables 3 and 4.

[0229] Table 3

[0230]

[0231] Table 4

[0232] The light microscopy images of Figure 1 demonstrate either the absence or presence of an emulsion of the active ingredient and the oligomers to form the shell (no emulsion means no capsule can be formed). These images were taken using a

[0233] Leica DMI8 optical microscope at 100x magnification. Without the use of a rheological agent, no emulsion is formed. In the presence of a rheological agent, an emulsion and the final capsule formation through polymerization can be observed.

[0234]

[0235] Table 5

[0236] Example 4: Encapsulation of Peppermint Oil

[0237] Microcapsules are prepared by applying the protocol as described above in example 1 .

[0238] Core (C1 ) composition:

[0239] 70% peppermint oil

[0240] 25% sesame seed oil

[0241] 5% rheological agent: Aerosil R812

[0242] Core viscosity (measured at 10s-1): 162.37 mPa.s

[0243] Core / shell ratio: 50 / 50

[0244] Table 6 below shows a volatility reduction as %loss of peppermint oil over time, encapsulated versus unencapsulated.

[0245] Table 6

[0246] Unencapsulated peppermint oil shows a near complete evaporation after 3 days.

[0247] Encapsulated peppermint oil shows a retention of the active in the capsule after 3 days.

Claims

CLAIMS1. A solid cross-linked microcapsule encapsulating at least one agrochemical ingredient or agrochemical preparation, said microcapsule having a mean diameter from 0.5 pm to 50 pm, said microcapsule comprising:- a core consisting of a composition C1 comprising at least one agrochemical ingredient or agrochemical preparation, and- a solid cross-linked polymer envelope totally encapsulating the core at its periphery, said solid cross-linked polymer envelope being made of a biodegradable cross-linked polymer, said polymer being an aliphatic nonaromatic polymer obtained by polymerizing one or several oligomer(s) or monomer(s), said polymer comprising preferably at least 20%, in particular at least 25%, and more preferably at least 30%, of ester groups by weight in comparison with the total weight of said polymer, and wherein the average thickness of said solid cross-linked polymer envelope is from 5% to 30% of the average diameter of said solid cross-linked microcapsule.

2. The solid cross-linked microcapsule of claim 1 , wherein the composition C1 further comprises from 1% to 20% by weight of a viscosifying agent relative to the total weight of said composition.

3. The solid cross-linked microcapsule of claim 2, wherein the viscosifying agent is selected from the group consisting of: fumed silica, clay, organic polymers such as hydrogenated vegetable oils, and hydrogels such as polysaccharides or hydrophilic silicates.

4. The solid cross-linked microcapsule of any one of claims 1 to 3, wherein the composition C1 further comprises from 5% to 40% by weight of a biodegradable carrier oil relative to the total weight of said composition C1 .

5. The solid cross-linked microcapsule of claim 4, wherein the composition C1 comprises from 5% to 30% by weight of a biodegradable carrier oil relative to the total weight of said composition C1 .

6. The solid cross-linked microcapsule of claim 4 or 5, wherein the biodegradable carrier oil is selected from the polyester oils.

7. The solid cross-linked microcapsule of any one of claims 1 to 6, wherein the agrochemical ingredient or agrochemical preparation is selected from the group consisting of: biocides, herbicides, fungicides, insecticides, nematicides, acaricides, rodenticides, biocontrol agents, biorationals, plant growth regulators, repellants, biostimulants, fertilizers, micronutrients, adjuvants, safeners for herbicides, synergists for insecticides, antitranspirants, fumigants and soil sterilizers, preservatives, or formulation ingredients like antioxidants.

8. The solid cross-linked microcapsule of any one of claims 1 to 7, wherein the composition C1 comprises from 20% to 80% by weight of agrochemical ingredient(s) or agrochemical preparation relative to the total weight of said composition.

9. The solid cross-linked microcapsule of any one of claims 1 to 8, wherein the aliphatic nonaromatic polymer of the solid cross-linked polymer envelope is obtained by polymerizing one or several oligomer(s) or monomer(s) M1 and M2, the molecular weight of M1 being from 1 ,500 to 10,000 g / mol and the molecular weight of M2 being from 50 to 1 ,500 g / mol, said oligomers M1 and M2 comprising preferably at least one reactive function selected from the group formed by acrylate, methacrylate, vinyl ether, N-vinyl ether, epoxy, siloxane, amine, lactone, phosphate and carboxylate functions.

10. The solid cross-linked microcapsule of any one of claims 1 to 9, wherein the solid cross-linked polymer envelope is formed through LIV polymerization.

11. The solid cross-linked microcapsule of any one of claims 1 to 10, being devoid of surfactant.

12. The solid cross-linked microcapsule of any one of claims 1 to 11 , further comprising lignosulfonate.

13. A formulation comprising at least one solid cross-linked microcapsule according to any one of claims 1 to 12.

14. The use of a solid cross-linked microcapsule of any one of claims 1 to 12, for reducing the volatility of an agrochemical ingredient or agrochemical preparation.

15. A method for reducing the volatility of an agrochemical ingredient or agrochemical preparation, comprising the encapsulation of an agrochemical ingredient or agrochemical preparation into a solid cross-linked microcapsule according to any one of claims 1 to 12.

16. The method of claim 15, wherein the release rate of the agrochemical ingredient(s) or agrochemical preparation is characterized by an exponential decay function N(t) = NOe~kt where the value of k varies from 0.6 to 1 .3 for t=1 and from 0.3 to 0.7 for values of t>1 , where t is measured in units of days, k is the rate of exponential decay and Nois the initial amount of agricultural protective product.

17. A method comprising for treating a plant, and / or soil and / or undesirable pest and / or weed and / or water surface comprising the application of the formulation according to claim 13 onto said plant and / or soil and / or undesirable pest and / or weed and / or water surface.

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