FR3133522A1 - ENCAPSULATED PHEROMONE FORMULATIONS RESISTANT TO LIGHT RADIATION - Google Patents

Abstract

The present invention relates to pheromone microcapsules comprising carbon black particles, as well as their manufacturing process and their use in the protection of crops exposed to solar or artificial light.

Description

ENCAPSULATED PHEROMONE FORMULATIONS RESISTANT TO LIGHT RADIATION TECHNICAL FIELD OF THE INVENTION

The present invention relates to encapsulated pheromone formulations resistant to light radiation. More particularly, it relates to pheromone microcapsules comprising carbon black particles, as well as their manufacturing process and their use in the protection, against harmful animals such as insects or mammals, of plants and crops, in particular in case of exposure to light.

STATE OF THE ART

The encapsulation of pheromones is a method of choice to allow the delivery of these active ingredients in crops, parks, gardens or forests, in particular for pheromones useful for attracting pests or for disrupting their reproduction through a confusion mechanism. sexual. The pheromones thus vectorized can be insect pheromones as well as mammalian pheromones.

The natural function of a pheromone is to carry information from one individual of a species to other individuals to provoke a specific reaction. These pheromones are molecules or mixtures of molecules that are very precise in terms of stereochemistry and in terms of component ratio. In the world of phytosanitary products, their actions in the fields must last for periods ranging from 4 weeks to 6 months. If encapsulation makes it possible to slow down the diffusion by evaporation of the pheromone, it does not guarantee the duration of effectiveness of the product if the stability of the active ingredients in the capsules, before their evaporation, has not been considered. Several examples of pheromones can illustrate this point depending on the animal families concerned. Table 1 below illustrates the pheromones of certain Lepidoptera containing conjugated unsaturated compounds.

Insect (lepidoptera) Main component of the pheromone Lobesia
( I ) Codling moth
( II ) Tomato leaf miner
(III) Chestnut leafminer
( IV ) Pine processionary
( V ) Amyelois transitella
(navel orangeworm in English)
( VI ) Grapholita molesta
( VIII )

( IX )

Likewise, the alarm pheromone of a large number of aphids is b-farnesene with the following structure (VII):

[Chem. (VII)]

This pheromone is also an attractant of aphid predators and can be used for this property to protect crops. It is sensitive to light (visible or UV) and any modification of geometry or functionality alters the use of the molecule as an information vector for insects (both for the aphid and for its predators).

All compounds (I) to (VI) are the majority compounds of the sexual pheromones of females of the species. Changing a structural parameter of these molecules makes them ineffective. In particular, isomerizations of cis double bonds quench the activity of these compounds. These isomerizations can be caused by free radicals but also by interactions with photons of variable wavelengths.

Numerous academic studies have studied the phenomena leading to the isomerization of these compounds in storage (absence of light) and in the fields (exposed to daylight and air). Thus, Brown et al. ( Economic Entomology, vol. 79, no. 4 , 1986, p. 923) study formulations based on elastomers impregnated with pheromones (I) and (II) making it possible to limit the impact of light on these pheromones. They show, like other following works (see J. Vrkoc et al. J. of Chem. Ecology, 4, 5, 1988, p. 1347), that the choice of material is essential for good stability of the pheromones during the storage and during use in the field, red elastomers having a worse performance than black elastomers which themselves have a worse performance than gray elastomers. According to these authors, the factor most favoring the isomerization of pheromones is firstly the type of vulcanization used for the manufacture of elastomers: that with sulfur, generating disulfide, induces a very high rate of isomerization while that with crosslinked phenolic resins, urethanes or peroxides do not induce isomerization. As pheromones are often a very expensive component of phytosanitary formulations for mating disruption or other pest control techniques, their stability during use must be optimized to optimize their effectiveness which lies in their diffusion in the environment. 'air.

When it comes to stabilizing these pheromones based on compounds comprising photosensitive conjugated unsaturated systems, those skilled in the art have used chemical stabilizers.

For example, in US5364969, the authors describe the use of a phenolic antioxidant (such as butylated hydroxytoluene or BHT) in combination with an anti-UV additive: Tinuvin® 536 from the benzotriazole family. In US6252106, it is the anti-UV compound Tinuvin® P of the benzotriazole type which is used at levels between 0.1% and 10% by weight relative to the weight of the pheromone.

In WO2002/080672, the authors mix the pheromones with di-tert-butyl-2,2'-methylenedi-p-cresol (MBMBP) as an antioxidant and this mixture is used with any type of pheromone diffuser such as microcapsules (e.g. microcapsules based on urea, gelatin or liposomes), microbeads, laminated plastic flakes and larger mechanical devices such as hollow fibers or twist ties. The authors indicate that this antioxidant can be associated with UV inhibitors such as carbon blacks or titanium dioxide but no particular example supports this possibility, even less in the context of the use of microcapsules. Indeed, these mineral fillers having particle sizes of the order of microns, their insertion into microcapsules does not appear obvious. At best, we can consider the simultaneous presence of microcapsules of pheromones and carbon blacks or the use of other larger diffusion systems.

In WO2017/050956A1 and WO2016/131883A1, the applicant described a particular process for encapsulating pheromones having the particularity of not requiring chemical reactions to construct the microcapsules which are organized under the action of the forces of attraction and repulsion of fatty components and water controlled by HASE type additives (Hydrophobic Alkali Swellable Emulsion in English). In these applications, pheromone stabilizers are chemical molecules soluble with the pheromone and remaining at the heart of the microcapsules. The stabilizing molecules are ter-butyl hydroquinone, propyl gallate, t-butyl-hydroxy anisole, p-methyl-hydroxy-benzoate, N,N-diethyl-toluamide, BHT, alpha-thioglycerin, nitroxides and alkoxyamines. These products are known antioxidants and UV inhibitors. The sizes of the particles obtained are of the order of 0.1 to 10 mm so that it is difficult to introduce carbon blacks which have similar dimensions.

The current state of the art therefore does not describe a way to introduce carbon blacks into microcapsules containing pheromones which could nevertheless solve the problem of photosensitivity of pheromones in microcapsules used as diffusers.

Carbon blacks are produced industrially using different processes such as those described in patent US9574087. These powders are in the form of grouped primary particles, agglomerated in clusters. The size of the primary particles can be of the order of a few tens of nanometers while the agglomerates have sizes of the order of several hundred nanometers. The properties conferred by carbon blacks on the materials in which they are dispersed are always linked to the state of dispersion of the carbon black in this material. The usual applications of carbon blacks are in the field of plastics (e.g. piping), elastomers (e.g. vehicle wheels), inks and varnishes, paints. In addition to mechanical properties, carbon blacks provide important electromagnetic properties (conductivity, absorption of radiation in a broad spectrum for example). The problem of dispersing carbon blacks is specific to each type of use because carbon blacks are both very hydrophobic and very poorly dispersible in organic environments that are not very polar.

The applicant has not found an example in the prior art making it possible to combine carbon blacks and pheromones effectively, and in particular in microencapsulated formulations of pheromones.

However, when it comes to stabilizing the stereochemistry of pheromones comprising conjugated systems such as pheromone compounds (I) to (IX), chemical antioxidants or UV blockers are not sufficient to maintain the correct isomerism when pheromone diffusers are exposed to sunlight and the use of carbon blacks could provide an economical and effective solution to this problem.

A very illustrative case is that of compound (VI) for which commercial products must include opaque containers to preserve the molecule for several months in the fields. As an example, mention can be made of aerosol bombs from the Semios or Suterra brands (see J. Beck, Journal of Agricultural and Food Chemistry, 2012, 60, 8090).

Another product from the Suterra company, Check Mate F Now (EPA registration number: 56336-38), comes in the form of a suspension of pheromone microcapsules in water containing 1.16% of the compound (VI). This product covers a culture for only 30 days which is less than the theoretical duration of evaporation of the compound reflecting a loss of active ingredient by chemical degradation.

There is therefore still a need to propose new formulations of light-sensitive pheromones to protect these pheromones from the harmful effects of light and to prolong the effectiveness of these formulations over time.

The subject of the present invention is thus microcapsules having a median diameter D50 ranging from 0.5 µm to 20 µm, preferably from 1 µm to 10 µm, containing a pheromone and carbon black particles.

Preferably, the microcapsules according to the invention comprise:

• a core comprising a mixture of wax, oil, pheromone (for example insect or mammal pheromone), and carbon black particles, preferably the primary particles of which have a median diameter D50 ranging from 10 nm to 50 nm, and
• a strong outer covering surrounding the heart.

The envelope may more particularly comprise a copolymer of the HASE type, possibly neutralized, totally or partially, in the form of a sodium, potassium or ammonium salt.

The core may also comprise one or more additives, preferably chosen from a dispersing additive, preferably non-ionic, carbon black particles, an anti-UV additive, an antioxidant and a mixture of these. Preferably, the core comprises a dispersing additive, preferably non-ionic, of carbon black particles.

The presence of carbon black particles in the microcapsules makes it possible to protect the pheromone also present in these microcapsules against light radiation and prevent its degradation and/or isomerization in the presence of light. The integrity of the pheromone is thus preserved during its exposure to light, allowing for longer effectiveness.

The present invention therefore also relates to the use of the microcapsules according to the invention, for the protection of a plant (in particular a crop) or a harvest against insects or mammals, in particular when said plant or crop is exposed to light (e.g. solar or artificial light).

The present invention also relates to a process for manufacturing microcapsules according to the invention. This process comprises mixing the ingredients forming the core of the microcapsules, namely wax, oil, pheromone (for example insect or mammal pheromone), carbon black particles, and possible additive(s), the formation of the cores of the microcapsules from this mixture and their coating with the material constituting the outer shell. This process can implement any technique for forming microcapsules, that is to say depositing an envelope around a core, known in the art.

When the outer envelope comprises a HASE type copolymer, said process advantageously comprises:

(a) the preparation of a fatty phase comprising the wax, the oil, the pheromone (for example insect or mammal pheromone), and the carbon black particles, and optionally one or more additives when they are present, the fatty phase having a temperature higher than the melting temperature of the wax,

(b) the preparation of an aqueous solution comprising the HASE type copolymer, the aqueous solution having a pH greater than or equal to 7.6, in particular greater than or equal to 8, in particular from 8 to 10, and a substantially identical temperature to that of the fatty phase,

(c) adding the fatty phase to the aqueous solution comprising the HASE type copolymer, and stirring so as to form a dispersion of fatty phase droplets in the aqueous solution, and

(d) acidification to a pH of 6 to 7.5, preferably 6.5 to 7.2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention therefore relates to microcapsules containing both active ingredients of the pheromone type and charges of the carbon black particle type which make it possible to stabilize these active ingredients when exposed to light, typically during use in the field. , thus increasing the effective life of these active ingredients.

Microcapsules

The microcapsules according to the invention have a median diameter D50 ranging from 0.5 µm to 20 µm, preferably from 1 µm to 10 µm, and comprise a core containing the pheromone type active ingredient(s) and the black particle type fillers. of carbon, this heart being surrounded by a solid outer envelope.

By “median diameter D50” of microcapsules is meant, within the meaning of the present invention, the median diameter of a distribution of microcapsules, that is to say the diameter such that 50% of the microcapsules by volume have a smaller diameter or equal to this value and that 50% of the microcapsules by volume have a diameter greater than this value. It is measured by laser diffraction, in particular using a Mastersizer 3000 device, in particular according to the method described in the experimental part.

By “pheromone” is meant, within the meaning of the present invention, a chemical substance or a mixture of chemical substances emitted by an animal and which represents a stimulus for individuals of this animal species. Such molecules can also stimulate individuals of other species, for example the territory pheromone of a predator such as the fox, which can be felt as a message of danger by rodent species. Pheromones can be produced either by living organisms or by chemical synthesis.

Preferably, the pheromones used in the context of the present invention carry a photosensitive function, such as one or more unsaturations, preferably conjugated unsaturations.

By “unsaturation” is meant, within the meaning of the present invention, a C=C double bond or a C≡C triple bond.

By “conjugated unsaturations” is meant, within the meaning of the present invention, an unsaturation as defined above linked to another unsaturation as defined above by a single bond.

The pheromone will more particularly be an insect or mammal pheromone, such as a lepidopteran pheromone (such as a lepidopteran of the genus Lobesia, the codling moth, the tomato leafminer ( Tuta absoluta ), the chestnut leafminer, the pine processionary moth or Amyelois transitella ), or an aphid pheromone.

The pheromone may be an unsaturated long-chain lepidopteran pheromone, a terpene such as one of the molecules (I) to (VI), (VIII) and (IX) above, a sesquiterpene such as the molecule (VII) above, or a mixture thereof.

The pheromone may be more particularly chosen from the molecules (I) to (IX) above and their mixtures.

Carbon black particles are made up of primary particles which can clump together to form agglomerates. Preferably, the primary particles are not or are weakly agglomerated in the microcapsules according to the invention. They are therefore preferably dispersed in the microcapsules.

Preferably, the primary particles of the carbon black particles used in the context of the present invention have a median diameter D50 ranging from 10 nm to 50 nm, in particular from 10nm to 40nm, for example from 11nm to 30nm, in particular from 12nm at 20nm.

By “median diameter D50” of the primary particles of carbon black is meant, within the meaning of the present invention, the median diameter of a distribution of primary particles of carbon black, that is to say the diameter such that 50% of the particles by volume have a diameter less than or equal to this value and that 50% of the particles by volume have a diameter greater than this value. It is measured by electron microscopy, in particular as described in EA Grulke, SB Rice, J. Xiong, K. Yamamoto, TH Yoon, K. Thomson, M. Saffaripour, G. Smallwood, JW Lambert, AJ Stromberg, R. Macy, N. Briot, D. Qian, Size and shape distributions of carbon black aggregates by transmission electron microscopy, Carbon (2018).

Preferred carbon black particles are carbon black particles intended for applications in inks and surface coatings, such as Monarch® brand grades 430, 700, 800, 1100 and 1300 or grades 1200, 1600 and 1800 of the Emperor® brand from the Cabot company or the grades of the Special Black, Printex®, Arosperse® and NIPex® brands from the Orion Specialty Carbon Blacks company.

Preferably, the microcapsules according to the invention comprise a core containing the active ingredient(s) of the pheromone type and the fillers of the carbon black particle type, this core being surrounded by a solid outer envelope.

Heart of microcapsules

The core of the microcapsules advantageously represents from 90% to 99.9% by weight of the weight of the microcapsules.

The core comprises a mixture of pheromone (for example insect or mammal) and carbon black particles, and advantageously a wax and an oil.

Preferably, the core comprises, in particular is constituted by, a mixture of wax, oil, pheromone (for example from insect or mammal), carbon black particles, and one or more additives, preferably chosen from a dispersing additive, preferably non-ionic, of carbon black particles, an anti-UV additive, an antioxidant and a mixture of these. Preferably, the core comprises a dispersing additive, preferably non-ionic.

The heart will advantageously contain, in relation to the weight of the heart:

• from 0.5% to 30%, in particular from 0.5% to 20%, preferably from 1% to 10%, by weight of pheromone (for example from insect or mammal),
• from 0.01% to 10%, preferably from 0.1% to 5%, by weight of the carbon black particles,
• from 0.5% to 50%, in particular from 0.5% to 30%, preferably from 1 to 20%, by weight of wax, and
• from 20 to 95%, in particular from 30 to 90%, preferably 40 to 80%, by weight of oil.

The heart will preferably contain, in relation to the weight of the heart:

• from 0.5% to 30%, in particular from 0.5% to 20%, preferably from 1% to 10%, by weight of pheromone (for example from insect or mammal),
• from 0.01% to 10%, preferably from 0.1% to 5%, by weight of the carbon black particles,
• from 0.5% to 50%, in particular from 0.5% to 30%, preferably from 1% to 20%, by weight of wax,
• from 20% to 95%, in particular from 30% to 90%, preferably from 40% to 80%, by weight of oil, and
• up to 10% (e.g. 0.01% to 10%), in particular up to 5%, preferably from 0.1% to 5%, by weight of a dispersing additive, preferably non-ionic, of particles of carbon black relative to the weight of the heart.

Preferably, the dispersing additive, preferably non-ionic, of the carbon black particles is present in the core in a quantity by weight less than or equal to that of the carbon black particles.

In particular, the core may contain up to 10% (e.g. 0.01% to 10%), in particular up to 5%, preferably 0.1% to 5%, of one or more additives.

By “wax” is meant, for the purposes of the present invention, a compound that is lipophilic and solid at room temperature (approximately 25°C) and atmospheric pressure (1013.25 hPa), preferably of natural origin. Preferably, the wax has a melting temperature greater than 45°C at atmospheric pressure.

The waxes capable of being used in a composition according to the invention can be chosen from waxes of animal origin, waxes of plant origin, mineral waxes, synthetic waxes and mixtures thereof. As wax of animal origin, we can cite beeswax, lanolin wax, or even Chinese insect wax. As a wax of plant origin, we can cite rice wax, carnauba wax, candelilla wax, jojoba wax, ouricurry wax, esparto wax, cork fiber wax. , sugar cane wax, Japanese wax, or even sumac wax. As mineral wax, we can cite montan wax, microcrystalline waxes, paraffins, or even ozokerite. As synthetic wax, we can cite polyethylene waxes, waxes obtained by the Fisher-Tropsch synthesis, or even waxy copolymers and their esters. The hydrogenated derivatives of the waxes mentioned above can also be used as wax in the context of the present invention. We can also cite waxes obtained by catalytic hydrogenation of oils of animal or vegetable origin having unsaturated fatty chains, linear or branched, in C8-C32. Among these, we can in particular cite hydrogenated jojoba oil, hydrogenated sunflower oil, hydrogenated castor oil, hydrogenated coconut oil, or even hydrogenated lanolin oil, as well as tetrastearate of di-(trimethylol-1,1,1-propane). It is also possible to use waxes obtained by transesterification and hydrogenation of oils of vegetable origin, such as castor or olive oil, such as the waxes sold under the names Phytowax ricin 16L64®, Phytowax ricin 22L73® and Phytowax Olive 18L57® by the company SOPHIM.

Advantageously, the wax is chosen from the group consisting of beeswax, lanolin wax, Chinese insect wax, rice wax, carnauba wax, candelilla wax, jojoba wax, ouricurry wax, esparto wax, cork fiber wax, sugar cane wax, Japanese wax, sumac wax, montan wax, microcrystalline waxes, and mixtures thereof.

By “oil” is meant, within the meaning of the present invention, a fatty compound, liquid at room temperature and atmospheric pressure, immiscible with water and non-volatile.

The oil according to the invention may be chosen from oils of vegetable origin, oils of animal origin, synthetic oils, and mixtures thereof; preferably chosen from oils of vegetable origin, oils of animal origin, and mixtures thereof. The oil of vegetable origin will advantageously be chosen from the group consisting of sunflower oil, peanut oil, soybean oil, rapeseed oil, corn oil, vegetable oil. olive, grape oil, walnut oil, flaxseed oil, palm oil, coconut oil, argan oil, avocado oil, oil almond oil, hazelnut oil, pistachio oil, rice oil, cottonseed oil, wheat germ oil, sesame oil, and mixtures thereof. The oil of animal origin will advantageously be chosen from the group consisting of cod liver oil, shark oil and their mixtures.

One or more additives may also be present in the core of the microcapsules, preferably chosen from a dispersing additive, preferably non-ionic, of carbon black particles, an anti-UV additive, an antioxidant and a mixture of those. -this.

The dispersing additive, preferably non-ionic, of the carbon black particles can be Disperbyk® 163 from the company Byk Chemie or the product Borchi® Gen 0451 from the company Borchers. Such dispersants can be prepared according to EP2091984 or even EP2125909, the teaching of which is incorporated by reference concerning the compositions and copolymers useful as dispersing agent.

Anti-UV additives or antioxidants well known to those skilled in the art can be added to limit the oxidation reactions caused by oxygen on the surface of the particles such as tert-butylhydroxytoluene (BHT), tert-butylhydroxyanisole (BHA), tocopherol, oxybenzone, octabenzone, derivatives of the benzotriazole family (such as 2-(2'-hydroxy-3',5'-tertamylphenyl)benzotriazole, or 2-(2 '-hydroxy-3'-tert-butyl-5'-methyl-phenyl)-5-chlorobenzotriazole), propyl gallate, or derivatives of 4-tetramethyl-piperidine, notably known under the name HALS ("hindered amine light stabilizers” in English, or hindered amine photo-stabilizers) and described in Schaller, C., Rogez, D. & Braig, A. “Hindered amine light stabilizers in pigmented coatings. » J Coat Technol Res 6, 81–88 (2009), and its nitroxides (obtained by oxidation of HALS as indicated in FR2788272).

Microcapsule shell

The envelope will advantageously comprise a copolymer of the HASE type, optionally neutralized, totally or partially, in the form of a sodium, potassium or ammonium salt.

By “HASE type copolymer” (HASE being the abbreviation of “Hydrophobically modified Alkali Swellable Emulsion”, namely an emulsion capable of swelling in an alkaline medium modified in a hydrophobic manner), is meant, within the meaning of the present invention, a copolymer of (meth)acrylic acid (e.g. methacrylic acid), alkyl acrylate (e.g. ethyl acrylate) and one or more hydrophobic macromonomers of formula Chem. Next:

in which :

• m is an integer greater than or equal to 5, preferably between 10 and 30, and
• R a hydrocarbon group of formula C _n H _2n+1 in which n is an integer between 9 and 25, preferably between 10 and 22 and more preferably equal to 12, 16 or 22. The group R is therefore hydrophobic

By “neutralized, totally or partially”, is meant, within the meaning of the present invention, that all or part of the carboxylic acid functions (COOH) carried by the HASE type copolymer are in salt form, and more particularly in sodium, potassium or ammonium salt form.

Advantageously, the HASE type copolymer comprises, in particular consists of, relative to the total weight of the copolymer:

• between 30% and 40% by weight of repeating units derived from methacrylic acid,
• between 45% and 60% by weight of repeat units from ethyl acrylate, and
• between 5% and 20% by weight of repeating units from a macromonomer of formula Chem. Next:

in which :

• m is an integer greater than or equal to 5, preferably between 10 and 30, and
• R a hydrocarbon group of formula C _n H _2n+1 in which n is an integer between 9 and 25, preferably between 10 and 22 and more preferably equal to 12.

The HASE type copolymer can be prepared for example according to one of the methods described in WO2011/104599, WO2011/104600 and EP1778797. This may be Pharma 38 or Viscoatex 730LV from the Coatex company.

Manufacturing process

The microcapsules according to the invention can be prepared according to the process described above, and in particular according to steps (a) to (e) when the outer shell comprises a HASE type copolymer. The microcapsules will advantageously be prepared in the form of an aqueous suspension.

Step (a)

The fatty phase is prepared in step (a) so as to obtain a mixture of wax, oil, pheromone (for example insect or mammal pheromone), carbon black particles, and a or several additives (preferably chosen from a dispersing additive, preferably non-ionic, of carbon black particles, an anti-UV additive, an antioxidant and a mixture thereof) having the composition of the core described herein -Before.

The fatty phase is maintained, preferably with stirring, at a temperature higher than the melting temperature of the wax so as to be liquid. In a particular embodiment, the fatty phase is at a temperature of 50°C to 85°C, in particular 60°C to 80°C.

Advantageously, the fatty phase is prepared by mixing the oil and the additive(s) (in particular the dispersing additive, preferably non-ionic, of the carbon black particles) which is heated to a temperature above the melting temperature. wax, then adding the wax, then adding the carbon black particles and the pheromone.

Step (b)

The aqueous solution of step (b) may be prepared by basifying an aqueous solution comprising the HASE type copolymer by adding a base, so as to obtain a pH greater than or equal to 7.6, in particular greater than or equal to 8, in particular from 8 to 10. This base will advantageously be chosen from sodium or potassium carbonate, ammonium hydroxide or ammonia in aqueous solution, sodium hydroxide, potassium hydroxide and their combinations.

Advantageously, the aqueous solution comprises from 0.1% to 10%, in particular from 0.1% to 5%, preferably from 0.1% to 1%, by weight of the HASE type copolymer relative to the weight of the aqueous solution.

This aqueous solution is then heated to a temperature substantially identical to that of the fatty phase.

By “substantially identical temperature” to that of the fatty phase, we advantageously mean a temperature not varying by more than 10°C, in particular by more than 5°C, relative to the temperature of step (a). Preferably, the temperature of step (b) will be identical to that of step (a).

Thus, the aqueous solution is advantageously at a temperature of 50°C to 85°C, in particular 60°C to 80°C.

Step (c)

In this step, the fatty phase having the temperature of step (a) is added to the aqueous solution having the temperature of step (b). The fatty phase droplets formed in the aqueous solution will form the core of the microcapsules.

Step (d)

Acidification makes it possible to precipitate the HASE type copolymer present in the aqueous solution on the droplets which then become microcapsules comprising the core based on the fatty phase surrounded by the solid envelope based on the HASE type copolymer. These particles are dispersed in water and thus form an aqueous suspension of the microcapsules.

In a particular embodiment, the acidification is carried out by adding an acid such as hydrochloric acid, phosphoric acid, sulfuric acid, an organic acid of the carboxylic acid type (particularly acetic acid or propionic acid) or a mixture of these, in particular phosphoric acid, until reaching a pH of 6 to 7.5, preferably 6.5 to 7.2. This acid is preferably added in the form of an aqueous solution.

The temperature of the aqueous suspension of the microcapsules thus obtained is then advantageously brought to a temperature below the melting point of the wax, in particular at a temperature between 20°C and 30°C.

According to a particular embodiment, the method implements the steps below.

• First step (step (a)): In a mixer equipped with a heating system and mechanical stirring, the oil and the additive(s), such as the dispersing additive, preferably non-ionic, particles of carbon black, are mixed and brought to a temperature above the melting temperature of the wax, then the wax is added. The mixture is homogenized before adding the carbon black particles and the pheromone. This phase represents a quantity Q expressed in kilograms.
• Second step (step (b)): In a reactor equipped with a high shear stirrer, water, preferably in a quantity Q, and the HASE type copolymer, preferably in an amount of 0.1% to 10 % w/w, in particular from 0.1% to 5% w/w, preferably from 0.1% to 1% w/w, are mixed, then the pH is brought to a value greater than or equal to 8, in particular from 8 to 10, using a basic solution, preferably at a concentration of 5% to 10% w/w, of sodium hydroxide, potassium hydroxide, or ammonia. When the solution is clear, the temperature is brought to the temperature of the mixture from the first stage.
• Third step (step (c)): The mixture from the first step (fatty phase) is added with stirring to the aqueous phase so as to form droplets. When the addition is completed, stirring can be continued, in particular for 10 min to 2 hours.
• Fourth step (step (d)): The pH is brought to a value of 6 to 7.5, preferably 6.5 to 7.2, by means of an acid solution, such as phosphoric acid , sulfuric acid or hydrochloric acid, in particular at a concentration of 2 to 10% by weight. Acidification allows the coalescence of the HASE type copolymer on the surface of the droplets, thus forming the solid envelope around the cores of the microcapsules. The resulting aqueous suspension of the microcapsules is then brought to room temperature, possibly with stirring.

Use

The present invention also relates to the use of the microcapsules according to the invention for the protection against insects or mammals of a plant (in particular a crop) or a crop, in particular when said plant or crop is exposed to the light, for example solar or artificial.

Pheromones will make it possible to influence the behavior of animals such as insects (e.g. lepidoptera or aphids), rodents, or even game (e.g. roe deer, deer, fallow deer, wild boars) responsible for damage to plants (especially crops). ) and harvests. The pheromone(s) will be chosen according to the animal (e.g. insect or mammal) against which we wish to protect the plant or harvest. For example, the pheromone could be chosen to lure a lepidopteran according to a trapping protocol or according to a sexual confusion protocol.

The microcapsules according to the invention, more particularly in the form of an aqueous suspension, can be applied by means of techniques known to those skilled in the art on supports present in the storage location (walls, posts, floors, etc.) or on bags containing the seeds.

In the case of protecting a plant, the microcapsules, in particular in the form of an aqueous suspension, may more particularly be applied to plants, in particular to their foliage, for example by means of a spray system.

The plants to be protected will advantageously be crops. These crops can, for example, be in the form of a covered plot (e.g. greenhouse, nursery) or an open plot (e.g. fields, forest).

Preferably, the plants to be protected are vines, field crops (rice, corn, cotton, soybeans, sunflowers, etc.), market garden crops (tomatoes, salads, peppers, melons, cucumbers). , cabbages, spinach, etc.), trees (e.g. fruit or ornamental trees (apple trees, peach trees, pear trees, citrus fruits, almond trees, etc.), forests (pine forests, oak forests …)), or shrubs (boxwoods…).

The crops to be protected will more particularly be seeds such as wheat, corn, etc. This will involve protecting these seeds during storage.

FIGURE

: photograph obtained by optical microscopy of the microcapsules obtained in Example 1.

: monitoring of the isomerization over time of the pheromone of formula (I) encapsulated in microcapsules with or without carbon black particles and subjected to light radiation (daylight).

EXAMPLES

- The pheromones used in the examples are manufactured by the applicant according to methods known to those skilled in the art. The HASE type copolymers used, namely Pharma 38 and Viscoatex 730VL, were supplied commercially by the company Coatex. The carbon black particles used in the examples consist of primary particles having a median diameter D50 of 14 to 20 nm.

- The size of the microcapsules is measured by light diffraction analysis with a Mastersizer 3000 device by diffraction of a laser beam. The measurement protocol is as follows:

The samples are first prepared by dispersing 0.5 g of formulation in 100 ml of demineralized water with magnetic stirring for 10 min. Then we proceed to measure the particle sizes, first taking care to align the device and measure the background noise to record the diffraction phenomena generated by the water. The sample is then introduced into the measuring cell and 5 successive measurements are carried out. The particle size is then determined by taking the average of these 5 measurements.

- The analysis of pheromone contents is carried out by gas chromatography (CPG) with a flame ionization detector on an Agilent - HP series II 5890 device.

- Pheromone release studies are carried out in ventilated ovens without windows so as not to be exposed to light radiation. These studies are carried out using two methods, either by monitoring the weight loss of the samples, or by monitoring the residual concentration of the pheromone in the sample by CPG.

- Accelerated aging studies under light to study photochemical degradation (for example isomerization) are carried out in daylight or in the laboratory using a tabletop solar simulator, the Solartest 1200.

- Optical microscopy is carried out on a ZEISS brand AXIO PLAN 2 microscope. Observations of the samples are carried out in transmission with a 40x plane and 20x plane objective. A ZEISS brand AxioCam ICC3 camera allows images to be viewed on a computer screen.

For example 3b the pheromonal mixture of Grapholita molesta was used. This mixture is composed of the following two molecules (VIII) and (IX) in a 15/85 ratio:

[Chem. (VIII)]

[Chem. (IX)]

Example 1: Microcapsules with the pheromone (I)

Into a 500 mL double-jacketed glass reactor, fitted with mechanical stirring, 200 g of sunflower oil are introduced, then 2 g of Disperbyk® 163 (additive dispersing carbon black particles). The mixture is brought to a temperature of 80°C, then 90g of purified beeswax is added. Once returned to 80°C, 2g of Emperor® 1200 carbon black particles are added. After a few seconds, the mixture becomes homogeneously black and 15g of pheromone (I) is then added. The core formulation is left stirring during the preparation of the shell formulation.

In a 1L double-jacketed reactor, equipped with a magnetic stirrer, 307 mL of deionized water are added, then 9.6g of Viscoatex 730LV (i.e. 3.2g of dry matter). A 10% soda solution is then poured drop by drop to reach a pH of 8.5. This corresponds to a mass of 5.2g of sodium hydroxide solution under stirring. The formulation becomes thick and translucent with bluish reflections. The temperature of the solution is then brought to 80°C.

Using a peristaltic pump, the core formulation is transferred into the 1L reactor at a flow rate of 5 mL per minute. In order not to freeze the oily phase in the transfer pipes, they are immersed in a water bath at 80°C.

The viscosity of the medium gradually increases. At the end of the addition, stirring is continued for an additional hour, stopping the heating. When the temperature reaches 60°C, 11 mL of a 4% phosphoric acid solution by weight is added with vigorous stirring. The formulation becomes fluid and reaches a pH of 6.7. Once everything has returned to room temperature, a suspension of gray microcapsules is recovered.

Characteristics obtained:

• Dry extract: 48%
• Encapsulation rate T: 99.7%

T = (amount of (I) total - amount of (I) in water)/amount of (I) total

• Median diameter D50: 7 µm
• Characterization by microscopy: cf. photo in

This photo shows that the carbon black particles are inside the microcapsules.

• Release of the pheromone in an oven at 30°C:

2 g of the microcapsule suspension are placed in plastic cups and placed in an oven. The T0 of the study takes place 24 hours after this incubator. A cup is then analyzed regularly by measuring its weight and by CPG analysis to estimate the release of the pheromone under these conditions. For a study over 80 days, a cup is taken on D3, D7, D12, D20, D31, D40, D60 and D80.

A controlled release is observed over several weeks. Thus, the presence of carbon black particles in the microcapsules does not hinder the encapsulation and prolonged release of the pheromone.

• Monitoring the isomeric ratio over time:

The results obtained are presented on the . The measurements show that the isomerization of the pheromone (I) is less rapid for the formulation with carbon black particles than for the control corresponding to the same formulation devoid of carbon black particles. This illustrates the better stability of the pheromones in the microcapsules according to the invention.

Example 2: Microcapsules with the pheromone (VI) and different contents of carbon black particles

The microcapsules of this example were prepared according to the procedure described in Example 1 using the ingredients mentioned in Table 2 below (the additive(s) being added just after the oil).

Part of the microcapsule Ingredient Example 2a Example 2b Example 2c Weight in g Heart Formulation Pheromone (VI) 3.00 3.03 2.95 Sunflower oil 64.83 65.13 65.33 Beeswax 0.65 0.63 0.68 Emperor® 1600
(carbon black) 0.63 0.33 0.15 BHT
(antioxidant) 1,902 1.80 1.91 Envelope wording Demineralized Water 166.86 167.86 167.83 Viscoatex 730LV
(in g of dry matter) 1.5 1.5 1.5 10% soda 2.73 2.73 2.73 H ₃ PO ₄ to 4% 4.53 3.65 3.58 Carbon black content compared to core formulation 0.9% 0.465% 0.2%

The encapsulation yields obtained with the three formulations 2a to 2c are presented in Table 3 below. They show that the presence of carbon black particles in the microcapsule, whatever their content, does not alter the encapsulation of the pheromone in the microcapsules.

Example 2a Example 2b Example 2c Dosage of total active substance 1.19% 1.26% 1.19% Dosage of free active substance 0.01% 0.003% 0.012% Encapsulation yield 99.19% 99.33% 98.94%

Example 3: Microcapsules with different pheromones and different formulations

The microcapsules of this example were prepared according to the procedure described in Example 1 using the ingredients mentioned in Table 4 below (the additive(s) being added just after the oil).

Part of the microcapsule Ingredient Example 3a Example 3b Example 3c 3d example Weight in g Heart Formulation Pheromone 130.2 36.6 57.3 5.5 Sunflower oil 350.6 230.0 378.0 120 Beeswax 3.5 94.0 155.3 1.2 Emperor® 1600
(carbon black) 0.45 0.4 0.6 0.6 Oxybenzone
(anti-UV additive) 11.9 - 8.9 0.7 BHT
(antioxidant) 11.8 8.5 15.2 3.5 Envelope wording Demineralized Water 500 800.0 1250.0 300.0 Pharma 38
(in g of dry matter) 17.6 13.2 23.5 4.9 10% soda 30.5 23.6 41.7 8.8 H ₃ PO ₄ to 4% 1.9 17.6 47.8 10.5 Nature of the pheromone (II) (VIII) / (IX) (I) (VI)

The encapsulation yields obtained with the four formulations 3a to 3d are presented in Table 5 below. These yields are very good whatever the formulation.

Example 3a Example 3b Example 3c 3d example Dosage of total active substance 12.3% 2.46% 2.7% 1.15% Dosage of free active substance 0.45% 0.008% 0.01% 0.019% Encapsulation yield 97.6% 99.4% 99.63% 98.3%

Example 4: Pheromone (VI) microcapsules with different encapsulating polymers

The microcapsules of this example were prepared according to the procedure described in Example 1 using the ingredients mentioned in Table 6 below (the additive(s) being added just after the oil).

Part of the microcapsule Ingredient Example 4a Example 4b Weight in g Heart Formulation Pheromone (VI) 10.8 10.5 Sunflower oil 231.8 231.7 Beeswax 23 23 Emperor® 1600
(carbon black) 1.16 1.16 BHT
(antioxidant) 6.4 6.8 Envelope wording Demineralized Water 600 572 Viscoatex 730LV
(in g of dry matter) 5.34 - Pharma 38
(in g of dry matter) - 9.4 10% soda 9.7 16.8 H ₃ PO ₄ to 4% 13 19.85

This example shows that different HASE type copolymers can be used to manufacture pheromone microcapsules according to the invention comprising carbon black particles.

Example 5: Effect of carbon black particles in the protection of pheromones

Microcapsules based on pheromone (VI) and various anti-UV additives instead of carbon black particles were prepared according to the process of Example 1 using the ingredients mentioned in Table 7 below (the or the additive(s) being added just after the oil).

Part of the microcapsule Ingredient Example 5a* Ex. 5b Example 5c* Ex. 5d* Weight in g Heart Formulation Pheromone (VI) 2.97 3.08 3.00 3.03 Sunflower oil 45.71 48.40 45.70 46.30 Beeswax 18.60 19.38 18.60 18.60 Anti-UV additive 1.10 0.33 1.10 0.63 BHT
(antioxidant) 1.80 1.88 1.90 1.90 Envelope wording Demineralized Water 161.02 162.08 161.03 160.58 Pharma 38
(in g of dry matter) 2.67 2.78 2.67 2.64 10% soda 4.73 4.93 4.73 4.73 H ₃ PO ₄ to 4% 5.20 0.68 5.05 5.45 Anti UV studied Oxybenzone Carbon black Tinuvin® 571 _TiO2

*comparative examples

The pheromone (VI) is very fragile and rearranges very easily into the E,Z isomer under the effect of visible light. After exposing the microcapsules of Examples 5a to 5d to daylight on cardboard strips, the change in the concentration of the different isomers remaining in the microcapsules is measured. The results obtained are presented in Table 8 below.

Rate of pheromone (VI) and its isomers in microcapsules (pheromone (VI) / isomers ratio) Example 5a Example 5b Example 5c Example 5d Day 0 100% (96/4) Day 5 92% 97% 95% 95% Day 10 85% 95% 90% 88% Day 15 79% (90.7/9.3) 92% (96/4) 84% (91.7/8.3) 83% (90.3/9.7)

These results show better stability (conservation of the initial isomeric ratio) of the active ingredient studied, namely the pheromone (VI), in microcapsules according to the invention containing carbon black particles compared to microcapsules containing anti- UV chemicals such as oxybenzone, Tinuvin® 571 or TiO ₂ , for a 2 to 4 times lower additive content in the microcapsules. This demonstrates that the microcapsules according to the invention release the pheromone only in the form of its effective active ingredient, unlike other microcapsules.

Example 6: Pheromone (VI) microcapsules with a high content of carbon black particles

The microcapsules of this example were prepared according to the procedure described in Example 1 using the ingredients mentioned in Table 9 below.

Part of the microcapsule Ingredient Example 6a Example 6b Weight in g Heart Formulation Pheromone (VI) 12 24 Sunflower oil 240 240 Beeswax 100 100 Emperor® 1600
(carbon black) 6 12 Disperbyk® 163
(dispersing agent) 6 12 Envelope wording Demineralized Water 600 600 Pharma 38
(in g of dry matter) 15 15 10% soda 9.7 9.5 H ₃ PO ₄ to 4% 13 12.8 Total pheromone rate 1.2% 2.3% Pheromone levels in hearts 3.3% 6.2% Level of carbon black in microcapsules 1.6% 3.1%

Example 7: Microcapsules with low concentrations of pheromones (III) and (IV) for use as diffusers for trapping tomato and chestnut leaf miners

The microcapsules of this example were prepared according to the procedure described in Example 1 using the ingredients mentioned in Table 10 below.

Part of the microcapsule Ingredient Example 7a Example 7b Weight in g Heart Formulation Pheromone 1g of III 1 g IV Sunflower oil 70 70 Beeswax 30 30 Emperor® 1600
(carbon black) 0.2 0.2 Disperbyk® 163
(dispersing agent) 0.2 0.2 Envelope wording Demineralized Water 100 100 Pharma 38
(in g of dry matter) 3 3 10% soda 2.1 2 H ₃ PO ₄ to 4% 0 0 Nature of the pheromone (III) (IV)

These two formulations have an encapsulation rate greater than 99%.

Claims (17)

Microcapsules having a median diameter D50 ranging from 0.5 µm to 20 µm, preferably from 1 µm to 10 µm, containing a pheromone and carbon black particles. Microcapsules according to claim 1, characterized in that the carbon black particles consist of primary particles having a median diameter D50 ranging from 10 nm to 50 nm, in particular from 10nm to 40nm, for example from 11nm to 30nm, in particular from 12nm to 20nm. Microcapsules according to claim 1 or 2, characterized in that the pheromone carries a photosensitive function, in particular one or more unsaturations, preferably conjugated unsaturations. Microcapsules according to any one of claims 1 to 3, characterized in that the pheromone is an insect or mammal pheromone such as a lepidopteran pheromone, an aphid pheromone or a mixture of these. Microcapsules according to any one of claims 1 to 4, characterized in that the pheromone is chosen from the following molecules (I) to (IX) and their mixtures:
[Chem. (I)]

[Chem. (II)]

[Chem. (III)]

[Chem. (IV)]

[Chem. (V)]

[Chem. (VI)]

[Chem. (VII)]

[Chem. (VIII)]

[Chem. (IX)]
Microcapsules according to any one of claims 1 to 5, comprising:
- a heart comprising a mixture of wax, oil, pheromone, and carbon black particles, and
- a solid outer covering surrounding the heart. Microcapsules according to claim 6, characterized in that the core represents from 90% to 99.9% by weight of the weight of the microcapsules. Microcapsules according to claim 6 or 7, characterized in that the heart contains, relative to the weight of the heart:
- from 0.5% to 30%, in particular from 0.5% to 20%, preferably from 1% to 10%, by weight of pheromone,
- from 0.01% to 10%, preferably from 0.1% to 5%, by weight of carbon black particles,
- from 0.5% to 50%, in particular from 0.5% to 30%, preferably from 1% to 20%, by weight of wax, and
- from 20% to 95%, in particular from 30% to 90%, preferably from 40% to 80%, by weight of oil. Microcapsules according to any one of claims 6 to 8, characterized in that the core also contains a dispersing additive, preferably non-ionic, of carbon black particles. Microcapsules according to claim 9, characterized in that the core contains up to 10%, in particular from 0.01% to 10%, preferably from 0.1% to 5%, by weight of additive dispersing black particles of carbon in relation to the weight of the heart. Microcapsules according to claim 9 or 10, characterized in that the additive dispersing carbon black particles is present in the core in a quantity by weight less than or equal to that of the carbon black particles. Microcapsules according to any one of claims 6 to 11, characterized in that the core also contains an anti-UV additive, an antioxidant or a mixture of these. Microcapsules according to any one of claims 6 to 12, characterized in that the envelope comprises a HASE type copolymer, optionally neutralized, totally or partially, in the form of a sodium, potassium or ammonium salt. Use of microcapsules according to any one of claims 1 to 13, for the protection of a plant or crop against insects or mammals, in particular when said plant or crop is exposed to light. Process for manufacturing microcapsules according to claim 13 comprising:
(a) the preparation of a fatty phase comprising wax, oil, pheromone, and carbon black particles, and optionally one or more additives when present, the fatty phase having a temperature higher than the wax melting temperature,
(b) the preparation of an aqueous solution comprising the HASE type copolymer, the aqueous solution having a pH greater than or equal to 7.6, in particular greater than or equal to 8, in particular from 8 to 10, and a substantially identical temperature to that of the fatty phase,
(c) adding the fatty phase to the aqueous solution comprising the HASE type copolymer and stirring so as to form a dispersion of fatty phase droplets in the aqueous solution, and
(d) acidification to a pH of 6 to 7.5, preferably 6.5 to 7.2. Method according to claim 15, characterized in that the temperature in step (a) and step (b) ranges from 50°C to 85°C. Process according to claim 15 or 16, characterized in that the aqueous solution prepared in step (b) comprises from 0.1% to 10%, in particular from 0.1% to 5%, preferably from 0.1 % to 1% by weight of the HASE type copolymer relative to the weight of the aqueous solution.