Process for the preparation of alginate capsules and capsules so obtained

Abstract

The present invention relates to a process for the preparation of a water dispersible dry microparticle, wherein said water dispersible dry microparticle at least one active ingredient, said process comprising the step of: a) preparing a dispersion of an alginate of a monovalent cation selected from an alkali metal and ammonium by adding the alginate of the monovalent cation to water; b) adding a metal salt to the dispersion of step a) thus obtaining a Mixture 1; c) preparing a Mixture 2 of at least one active ingredient; d) Adding Mixture 2 to Mixture 1 thus obtaining a feed composition; e) spray-drying the feed composition, thus obtaining the microparticles encapsulating the at least one active ingredient. The present invention relates also to dry microparticles, microcapsules and microspheres obtainable by the process of the invention and their use in agriculture field.

Description

[0001] P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0002] TITLE:

[0003] PROCESS FOR THE PREPARATION OF ALGINATE CAPSULES AND CAPSULES SO OBTAINED

[0004] ***** ***** *****

[0005] FIELD OF THE INVENTION

[0006] The present invention relates to a process for the preparation of water dispersible dry microparticles encapsulating either hydrophilic or hydrophobic active ingredient in eco-friendly alginate-based matrix microsystems.

[0007] The present invention relates also to dry microparticles obtainable by the process of the invention and their use for delivering said active ingredient in agriculture. STATE OF THE ART

[0008] Microplastics is a general term indicating solid polymeric particles less than 5 mm in length according to the European Chemicals Agency (ECHA). Once in the environment, not biodegradable microplastics are accumulated in marine, freshwater, and terrestrial ecosystems which lead to a big impact on the wildlife as well as on the whole food chain.

[0009] Many species mistake microplastics for food, leading to ingestion and potential health problems such as starvation, suffocation, and entanglement as reported by different researchers in the last decades. Furthermore, in an environment dominated by particulate material, microplastics can alter soil chemistry and affect soil organisms’ fitness and function.

[0010] In the literature it is shown that microplastics are frequently detected also in human samples since people are potentially exposed to microplastics through oral intake, inhalation, and skin contact as common ways. The effects connected with their introduction in human body mainly consist of oxidative stress, DNA damage, organ dysfunction, metabolic disorder, immune response, neurotoxicity, as well as reproductive and developmental toxicity. In addition, epidemiological evidence suggests that a variety of chronic diseases may be related to microplastics exposure.

[0011] In light of the above, in 2023, the European Commission adopted a REACHP024104WO-01 Notarbartolo & Gervasi S.p.A.

[0012] (Registration, Evaluation, Authorization and Restriction of Chemicals) restriction on microplastics intentionally added to products and a proposal for a Regulation on preventing plastic pellet losses to the environment.

[0013] The Ell aims to reduce microplastic releases by 30% by 2030. This will be achieved by

[0014] - reducing plastic pollution (as these degrade into microplastics),

[0015] - restricting the use of intentionally added microplastics to products, and

[0016] - reducing unintentional microplastic releases

[0017] The regulation defines synthetic polymer microplastic as: “polymers that are solid and which either are contained in particles and constitute at least 1 % by weight of those particles, or build a continuous surface coating on particles, where at least 1 % by weight of those particles fulfill either of the following conditions:

[0018] (a) All dimensions of the particles are equal to or less than 5 mm.

[0019] (b) The length of the particles is equal to or less than 15 mm and their length to diameter ratio is greater than 3.”

[0020] However, some exceptions are included, such as:

[0021] • degradable or water-soluble (>2 g / l) polymers and natural polymers that have not been chemically modified,

[0022] • biodegradable polymers, and

[0023] • polymers with no carbon atoms within their own structure.

[0024] Crop protection compounds, including herbicides, insecticides, fungicides, and plant nutrients are often encapsulated either in polymeric matrices or within a core-shell system in their formulation form to achieve one or more purposes listed below:

[0025] • obtaining an active ingredient-controlled release for optimum effectiveness, • retarding the losses of volatile components,

[0026] • protecting the active ingredient against light and oxidation,

[0027] • protecting either employers or final users from harmful or unpleasant materials,

[0028] • preventing premature chemical reactions with other mixture components, andP024104WO-01 Notarbartolo & Gervasi S.p.A.

[0029] • reducing actives side effects such as crop toxicity and drifting.

[0030] Nowadays, synthetic polymers such as polyacrylates, polyamides, polyvinyl alcohol or polyvinylpyrrolidone represent the most common materials for encapsulating pesticides.

[0031] Unfortunately, such materials lack of the required REACH characteristics described above, and the development of new environmentally friendly products is needed. Alginates are a class of polymers isolated from natural sources, typically extracted by the cell walls of brown seaweeds. They are composed by a linear polymer chain of (1-4) linked (3-D- mannuronic acid (M) and / or its C-5 epimer a-L-guluronic acid (G) which has the ability of mildly forming a gel when it encounters some polyvalent cations, namely Ba2+, Cu2+, Sr2+, Fe2+, Zn2+, Mn2+, Al3+, Fe3+,Cr3+, and Co2+. The properties of alginates can be tailored for specific applications by adjusting their chemical composition, molecular weight, and gelation conditions.

[0032] Various methods have been attempted to produce controlled release formulations using alginates as encapsulating material; for example, WO 2021 / 048857 discloses a method to produce non-dry compositions in the form of a sludge, slurry, or liquid for crop treatment.

[0033] US 9,157,054 B2 relates to a new device and the relative method to obtain crosslinked alginate using a 2-nozzle system where the polymer chain solution (containing the active ingredient) as well as the cross-linking solution are sprayed at the same time within a chamber. The encapsulation takes place when the aerosols contact each other.

[0034] EP 1 938 807 teaches the method for producing spray dried alginate capsules by pumping the polymer solution and the cross-linking agent in the drying chamber. The international application WO 2019 / 232410 describes a method for producing a spray dried alginate powder using a three-fluid nozzle in which the two solutions are introduced in separated coaxial chambers and atomized by a gas flowing in a third compartment.

[0035] Although the methods cited above are valid options to entrap active ingredients in alginate matrix, some drawbacks might be faced regarding the industrial processesP024104WO-01 Notarbartolo & Gervasi S.p.A.

[0036] and scale up. For example, liquid or semi-solid alginate-based formulation are generally less stable overtime than the solid counterparts whereas the procedures to obtain dry formulations require expensive and / or custom-made equipment.

[0037] A first object of the present invention is to provide a novel process of preparing microcapsules with improved properties comprising one or more active substances embedded in an eco-friendly alginate matrix material.

[0038] It is a further object of the invention to provide improved microcapsules for use in agriculture having improved properties, such as improved stability and a controlled and tunable release of the active ingredients, specifically for active ingredients having a high volatility.

[0039] A still further object is to improve the physical / chemical characteristics of the microparticles themselves. In fact, spray dried powders generally result in particles having an amorphous molecular arrangement. Such state is typically characterized by the tendency to absorb atmospheric moisture, causing particle aggregation, active recrystallization and solid-bridge formation leading to poor formulation physical stability overtime. This aspect might result problematic at both manufacturing and end customer levels in terms of flowability and accuracy, preciseness, and reliability of the active dosing as well as the powder capability of being readily dispersed in the user tanks. Those hinderances represent challenging drawbacks to overcome, particularly in an economic manner since protecting particles from moisture induced changes often requires successive coating treatments to be achieved (e.g. fluid bed processing, hot melt coating, MAIC). In the light of the above, is a further object of the invention a one-step spray drying method to provide improved microparticles for use in agriculture having enhanced properties in terms of physical stability and user-handling characteristics.

[0040] SUMMARY OF THE INVENTION

[0041] It has now been unexpectedly found by the present inventors that it is possible to produce water dispersible dry microparticles suitable for agricultural use, comprising at least one active ingredient which is encapsulated within an alginate-based matrix, preferably coated by a hydrophobic amino-acid based layer. The use of such waterP024104WO-01 Notarbartolo & Gervasi S.p.A.

[0042] dispersible dry microparticles and microspheres permits the tuned and controlled delivery of active ingredients ensuring a long term formulation stability and excellent flowing behavior at the same time.

[0043] Therefore, the invention relates to a process for the preparation of a water dispersible dry microparticle, wherein said water dispersible dry microparticle encapsulates one or more active ingredients, said process comprising the step of: a) preparing a dispersion of an alginate of a monovalent cation selected from an alkali metal and ammonium by adding the alginate of the monovalent cation to water; b) adding a metal salt to the dispersion of step a) thus obtaining a Mixture 1 ; c) preparing a Mixture 2 of at least one active ingredient;

[0044] d) Adding Mixture 2 to Mixture 1 thus obtaining a feed composition;

[0045] e) spray-drying the feed composition, thus obtaining the microparticle encapsulating the at least one active ingredient.

[0046] The inventors found out an inventive process that allows to obtain microparticles comprising the active ingredients for a tuned delivery in agriculture.

[0047] Preferably and advantageously, the process provides for a Mixture 2 that is an oil / water emulsion. The inventors of the present invention hence found out that the process according to the invention allows to obtain solid dry alginate-based microparticles. Comparing to liquid or semi-solid alginate-based formulation, the dry alginate-based microparticles of the invention are very stable and requires simple equipment. Moreover, advantageously the process of the invention uses an eco-friendly alginate-based matrix as an encapsulating agent in order to encapsulate very different crop protection agents. The use of an eco-friendly alginate-based matrix allows to avoid the use of microplastics and meet the requirements of the REACH restriction adopted by the European Commission.

[0048] The inventors faced with the problem of encapsulating very highly volatile liquid active ingredients and with active ingredients having a low solubilization rate.

[0049] The inventors advantageously found out the process for obtaining microparticles suitable for encapsulating highly volatile liquid active ingredients. The microparticles so obtained are solid and very stable.P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0050] The at least active ingredient is preferably a highly volatile liquid compound, more preferably an herbicide comprising in its structure an isooxazoline fragment, still more preferably clomazone, bixolozone, pyroxasulfone or fenoxasulfone. In a very advantageous and preferred embodiment the active ingredient is clomazone.

[0051] In a preferred embodiment the inventors found a one-step spray drying method to provide improved microparticles for use in agriculture having enhanced properties in terms of physical stability and user-handling characteristics by the avail of hydrophobic based amino acids additives.

[0052] Surprisingly the inventors provided for a preferred step c) of preparing a Mixture 2 of at least one active ingredient and of a mixture of hydrophobic amino acid based compounds.

[0053] Without being bound to any theory, the inventors deem that the hydrophobic based amino acids compounds could act as a barrier to moisture and slow down absorption / adsorption of moisture into the particles reducing hence the impact on molecular structure morphology resulting in free flowing and stable powder.

[0054] In a further aspect, the present invention relates to a water dispersible dry microparticle obtainable from the process described above, wherein the active ingredient is a highly volatile compound, or it is a compound with a low solubilization rate.

[0055] In a preferred and advantageous embodiment, the water dispersible dry microparticles of the invention comprises as the active ingredient clomazone. In a more preferred and advantageous embodiment the encapsulated clomazone is in amount from 5 to 30% w / w, preferably from 13 to 17% w / w with respect to the total amount of the microparticle.

[0056] The water dispersible dry microparticles obtainable by the process of the invention are suitable for delivering the active ingredients in agriculture field.

[0057] Advantageously the microparticles of the invention allow a tuned and controlled release of the active ingredient, depending on the action of the active principle. In a further aspect, the present invention relates to the use of said water dispersible dry microparticle in agriculture for delivering one or more active ingredients.P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0058] DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 shows the results of Example 3: Untreated com and OSR pots (A,B); EC treated corn (C) ;alginate particle treated corn (D); EC treated OSR (E); alginate particle treated OSR (F).

[0060] Figure 2 shows the percentage of phytotoxicity and efficacy according to Example 3.

[0061] Figure 3 shows the evolution of the biodegradation of replicates of reference item sodium acetate (based on CO2 production).

[0062] Figure 4 shows the evolution of the biodegradation of replicates of alginate microparticle (based on CO2 production).

[0063] DETAILED DESCRIPTION OF THE INVENTION

[0064] Therefore, the invention relates to a process for the preparation of a water dispersible dry microparticle, wherein said water dispersible dry microparticle encapsulates one or more active ingredients, said process comprising the step of: a) preparing a dispersion of an alginate of a monovalent cation selected from an alkali metal and ammonium by adding the alginate of the monovalent cation to water; b) adding a metal salt to the dispersion of step a) thus obtaining a Mixture 1 ; c) preparing a Mixture 2 of at least one active ingredient;

[0065] d) Adding Mixture 2 to Mixture 1 thus obtaining a feed composition;

[0066] e) spray-drying the feed composition, thus obtaining the microparticles encapsulating the at least one active ingredient.

[0067] In the present description the following terms and definitions will be used:

[0068] - “microparticle” means a particle made of a polymer and in the particle size range of 1- 1000 pm as measured by microscopy, laser diffraction and sieving methods and comprises in its definition the “microsphere” and “microcapsule”;

[0069] - the term “active ingredient” refers to any hydrophilic or hydrophobic chemical or biological component (ora combination thereof), the application of which causes or provide a beneficial and / or useful effect in agriculture including, but not limited to fertilizers and pesticides including acaricides, fungicides, herbicides, insecticides, and nematicides;P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0070] - the term “hydrophobic amino-acid based compound” refers to any amino-acid or oligopeptide (or a combination thereof) having a solubility in water at 25 °C of less than 5 mg / ml, preferably below 2 mg / ml. For example, these additives include molecules such as tryptophan, tyrosine, leucine, phenylalanine, isoleucine, valine, methionine, tri-leucine and the like;

[0071] - - “highly volatile liquid” means a liquid having a vapour pressure equal to or above 1 10’4mm Hg, and

[0072] - “active ingredient having a low solubilization rate means an active ingredient having a solubilization rate of equal to or less than 10 mg / L at 25°C.

[0073] The process comprises the step a) of preparing a dispersion of an alginate of a monovalent cation selected from an alkali metal and ammonium by adding the alginate of the monovalent cation to water.

[0074] The alginate of a monovalent cation selected from an alkali metal and ammonium of step a) can be preferably selected from potassium alginate, sodium alginate and ammonium alginate, preferably it is sodium alginate.

[0075] The dispersion of step a) is made with preferably distilled water.

[0076] In a preferred embodiment the dispersion of step a) comprises as alginate of a monovalent cation sodium alginate, preferably in the range from 2 to 10% (w / w), more preferably 4% (w / w) with respect to the total weight of the dispersion.

[0077] In step b) a metal salt is added to the dispersion of step a) thus obtaining a Mixture 1.

[0078] The metal salt of step b) can be selected from CaHPCU, Ca tartrate, Calcium oxalate, CaCOs, Barium oxalate, BaCOs, ZnCOs, Zn2(PO4)3, MnCOs, Mns(PO4)2 preferably the metal salt is calcium hydrogenphosphate (CaHPCU).

[0079] In a preferred embodiment, said metal salt of step b) can be present of Mixture 1 in the aqueous solution of the alginate of step a) in a cation / alginate guluronic residues molar ratio in the range from 0.5 to 5, preferably of 2.

[0080] In an advantageous and preferred embodiment, the Mixture 1 of step b) is homogenized, thus obtaining droplets having the desired size that can be monitored by optical microscopy. The homogenization can be carried out preferably with aP024104WO-01 Notarbartolo & Gervasi S.p.A.

[0081] speed in the range from 8.0 103to 1.3 104rpm for 3-20 minutes, more preferably at 1 -104rpm for 10 minutes with an homogenizer known in the art.

[0082] In step c) a Mixture 2 of at least one active ingredient is prepared.

[0083] Preferably and advantageously, the process provides for a Mixture 2 that is an oil / water emulsion.

[0084] The active ingredient can be selected from the group consisting of fertilizers, pesticides, comprising preferably acaricides, fungicides, herbicides, insecticides, and nematicides.

[0085] Preferably the active ingredient is a highly volatile liquid active ingredient or a compound, solid or liquid, having a low solubilization rate.

[0086] The at least active ingredient can be selected from the group consisting of

[0087] - a thiocarbamate herbicide, preferably triallate, diallate, butylate, cycloate, EPTC, molinate;

[0088] an herbicide selected from clomazone, bixolozone, pyroxasulfone and fenoxasulfone;

[0089] -a pyrethroid, preferably cyfluthrin, lambda-cyhalothrin, bifenthrin, permethrin, resmethrin;

[0090] - a dinitroaniline, preferably pendimethalin, trifluralin, ethalfluralin, oryzalin, butralin, benefin / benfluralin and prodiamine;

[0091] - a terpen and / or terpeoid, preferably d-limonene, azadirachtins, carvacrol, 1,8-cineole, anisole, limonene, [3-pinene, linalool, menthone, a-pinene, pulegone, myrcene eugenol, borneol, menthol, isomenthol, anethole, camphor, carvone, menthyl acetate, linalyl acetate, thymol, p-cymene, y-terpinene, a-terpineol, 4-terpineol, citronellol, geraniol; and

[0092] - an essential oil, preferably cinnamon oil, citronella oil, clove oil, eucalyptus oil, lemongrass oil, mint oil, mint oil, orange oil, peppermint oil, rosemary oil, thyme oil. The at least active ingredient is preferably a highly volatile liquid compound, more preferably a isoxazoline-derivate herbicide, still more preferably clomazone, bixolozone, pyroxasulfone or fenoxasulfone. The most preferred active ingredient is clomazone.P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0093] Clomazone, the common name for 2-(2-chlorophenyl)methyl-4,4-dimethyl-3-isoxazolidinone, is an active ingredient in highly effective herbicides that are selective against perennial weeds, including grasses and broadleaves. Clomazone works by inhibiting the biosynthesis of carotenoids in the plant; a plant affected by clomazone exhibits progressive whitening with increased dosage. Herbicides containing clomazone are applied to the soil for control of weeds on beans, cabbage, cucumbers, cotton, melons, mint, peas, peppers, rice, soybeans, squash, sugarcane, sweet potatoes, tobacco and tuberous vegetables. Such herbicides are selective against perennial weeds, including grasses and broadleaves.

[0094] Clomazone is a highly volatile compound and therefore it is a problematic active ingredient.

[0095] The same can be repeated for bixolozone, that is a highly volatile liquid herbicide characterized by high vapor tension, hence a significant volatility. Lambda-cyhalothrin, common name (RS)-alpha-cyano-3-phenoxybenzyl 3-(2-chloro-3,3,3-trifluoropropenyl)-2,2, -dimethylcyclopropanecarboxylate is a synthetic pyrethroid insecticide and acaricide used to control a wide range of pests in a variety of applications. Pests controlled include aphids, Colorado beetles and butterfly larvae. Crops on which it may be applied include cotton, cereals, hops, ornamentals, potatoes, vegetables, or others.

[0096] Lambda-cyhalothrin has a high toxicity degree and it is potentially lethal by inhalation and therefore it is a problematic active ingredient.

[0097] Triallate, IIIPAC name S-(2,3,3-trichloroprop-2-enyl) N,N-di(propan-2-yl)carbamothioate, belongs to the thiocarbamate chemical class. It is a preemergence selective herbicide used to control grass weeds in field and pulse crops. It is used selectively to control wild oats, black grass, and annual meadow grass in barley, wheat, peas, lentils, rye, maize, beets, brassicas, carrots, and onions.

[0098] Triallate needs to be finely released from capsules to carry out a proper weed control with no side effect on crops therefore it is a problematic active ingredient.

[0099] Surprisingly and advantageously, the process of the invention succeeded in encapsulating all these problematic above commented active ingredients suchP024104WG-01 Notarbartolo & Gervasi S.p.A.

[0100] clomazone, bixolozone, Lambda-cyhalothrin and triallate in a very efficient way as it will be clear from the experimental part.

[0101] Microencapsulated formulations of clomazone and bixolozonehave been developed to address the problem of high volatility.

[0102] In a preferred embodiment the inventors found a one-step spray drying method to provide improved microparticles for use in agriculture having enhanced properties in terms of physical stability and user-handling characteristics by the avail of hydrophobic based amino acids additives.

[0103] The step c) of preparing a Mixture 2 of at least one active ingredient can preferably comprise the presence of one or a mixture of hydrophobic amino acid based compounds. Without being bound to any theory, the inventors deem that the hydrophobic based amino acids compounds could act as a barrier to moisture and slow down absorption / adsorption of moisture into the particles reducing hence the impact on molecular structure morphology resulting in free flowing and stable powder.

[0104] The presence of at least one hydrophobic amino acid-based compound in the spray-dried mixture feed showed an improvement in spray-drying performance in terms of avoiding adherence to the walls, increasing the product yield.

[0105] In a preferred embodiment, wherein Mixture 2 is an emulsion oil / water (O / W), preferably in a ratio 1:100 by weight, more preferably prepared with a water phase of succinic acid, still more preferably a solution of succinic acid of 2% (w / w).

[0106] Mixture 2 was a slightly acidic pH by the addition of a base preferably having pH of 5.6, preferably with the addition of ammonium hydroxide.

[0107] In a more preferred embodiment of the invention, the water phase comprises also a surfactant selected from the group consisting of polysorbate-PEG based non-ionic surfactant, preferably it is tween 80.

[0108] Preferably the Mixture 2 comprises also one or more wetting agents, selected from the group consisting of anionic surfactant, preferably an alkyl naphthalene sulfonate based surfactant, more preferably in a weight percentage (%) in the range of 0.5 and 3%, preferably of 1.5 % with respect to the total weight of the emulsion.P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0109] In a preferred embodiment, the Mixture 2 of step c) is kept under agitation for a time in the range of 3 to 15 minutes, preferably 5 minutes at an agitation rate in the range of 8 103and 1,3-104rpm, preferably 1 104rpm.

[0110] In step d) of the process, Mixture 2 is added to Mixture 1 thus obtaining a feed composition

[0111] Preferably, the amount ratio of Mixture 2 to Mixture 1 in the adding step d) is in the range from 1:1 to 1:3, preferably 1:1.

[0112] According to a preferred embodiment, in step d) the Mixture 2 is added to Mixture 1 under agitation, preferably at 400 rpm for 5 minutes.

[0113] In step e) of the process of the invention a spray-drying is carried out.

[0114] The feed composition of step d) is pumped in step e) in a spray dryer obtaining water dispersible dry microparticles encapsulating one or more active ingredients.

[0115] Said spray-drying step e) is carried out according to the following parameters independently each other:

[0116] - an inlet temperature from 120 to 170°C, preferably 140°C;

[0117] - an atomizing gas rate from 7 to 11 L / min, preferably 10 L / min.

[0118] - an aspiration rate from 60 to 100%, preferably 70%.

[0119] - a feed pumping rate from 2 to 5 m l / min, preferably 3.4 m l / min.

[0120] The process of the invention allowed water dispersible dry microparticles res encapsulating one or more active ingredients within an alginate-based matrix to be obtained.

[0121] The process of the invention advantageously permits the encapsulation of one or more active ingredients with a loading in the range of 5 to 30%w / w .

[0122] In the preferred and advantageous embodiment wherein the active ingredient is clomazone, the encapsulated clomazone is in amount from 5 to 30% w / w, preferably from 13 to 17% w / w with respect to the total weight of the microparticle.

[0123] The inventors of the present invention hence found out that the process according to the invention allows to obtain solid dry alginate-based microparticles, microcapsules and microspheres. Comparing to liquid or semi-solid alginate-based formulation, the dry alginate-based microcapsules and microspheres of theP024104WO-01 Notarbartolo & Gervasi S.p.A.

[0124] invention are very stable and requires simple equipment. Moreover, advantageously the process of the invention uses an eco-friendly alginate-based matrix as an encapsulating agent in order to encapsulate very different crop protection agents. The use of an eco-friendly alginate-based matrix allows to avoid the use of microplastics and meet the requirements of the REACH restriction adopted by the European Commission.

[0125] The inventors faced with the problem of encapsulating very highly volatile liquid active ingredient and with active ingredients having a low solubilization rate.

[0126] The inventors advantageously found out a process for obtaining microparticles suitable for encapsulating highly volatile liquid active ingredients. The microparticles so obtained are solid and very stable.

[0127] In a very advantageous and preferred embodiment the active ingredient is clomazone.

[0128] In a further aspect, the present invention relates to a water dispersible dry microparticle obtainable from the process described above, wherein the active ingredient is a highly volatile compound or it is a compound with a low solubilization rate.

[0129] In a preferred and advantageous embodiment, the water dispersible dry microparticle of the invention comprises as the active ingredient clomazone. In a more preferred and advantageous embodiment the encapsulated clomazone is in amount from 5 to 30% w / w, preferably from 13 to 17% w / w with respect to the total amount of the microparticle.

[0130] The water dispersible dry microparticles obtainable by the process of the invention are suitable for delivering the active ingredients in agriculture field.

[0131] Advantageously the microparticles of the invention allow a tuned and controlled release of the active ingredient, depending on the action of the active principle. Preferably, the polyurethane microparticle has a D50 in the range from 1 pm to 40 pm, more preferably 1-15 pm and D90 in the range from 10 pm to 100 pm, more preferably from 15 pm to 40 pm as measured by a laser diffraction analyzer (more preferably analyzer Malvern 3000, Malvern Panalytical, Malvern, UK).P024104WG-01 Notarbartolo & Gervasi S.p.A.

[0132] In a further aspect, the present invention relates to the use of said water dispersible dry microparticle in agriculture for delivering one or more active ingredients.

[0133] EXPERIMENTAL PART

[0134] Example 1 : Preparation of the microparticle of the invention

[0135] Firstly, a Mixture 1 was prepared as follows

[0136] Sodium alginate Algogel 3001 (Algaia, Brest, France) was added in distilled water to obtain a 4% (w / w) dispersion under continuous agitation over night at room temperature. 49.9 g of dispersion were weighted in a separate beaker and 1 g of CaHPO4 (Sigma-Aldrich, Schnelldorf, Germany) were added; the mixture was homogenized by an Ultraturrax T50, (IKA, Staufen, Germany) at T104rpm for 10 minutes (Mixture 1).

[0137] The droplet size of the internal phase was monitored by optical microscopy.

[0138] Then a Mixture 2 was prepared as follows:

[0139] An O / W emulsion of clomazone (Sipcam-Oxon, Mezzana Bigli, Italy) as oil phase was prepared in parallel (ratio 1:100 by weight). The water phase was constituted by 2% (w / w) solution of succinic acid (Sigma-Aldrich, Schnelldorf, Germany) and 0.2 % (w / w) of tween 80 (surfactant) (Croda, Goole, UK). The mixture was kept under agitation for 5 minutes at T 104rpm and finally the pH was adjusted to 5.6 by adding ammonium hydroxide dropwise (mixture 2).

[0140] 500 ml of Mixture 2 were added to Mixture 1 under agitation at 400 RPM for 5 minutes and subsequently pumped into a Buchi B-290 spray dryer (Buchi Italia s.r. I. , Cornaredo, Italy).

[0141] A summary of the feed composition and the spray dryer parameter settings are described in Table 1 respectively.

[0142] Table 1. Spray dried feed composition

[0143]

[0144] P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0145]

[0146] Table 2. Spray dried parameter settings.

[0147]

[0148] The loading of clomazone within the dry powder was found to be 13.7% (w / w) by HPLC.

[0149] Particle size analyses were obtained by a laser diffraction analyzer (Malvern 3000, Malvern Panalytical, Malvern, UK) using water as dispersing medium, D50 and D90 obtained were 13.2 and 31.1 pm respectively.

[0150] Clomazone release from the alginate based microparticles analyses were performed by dispersing a known weight of powder in a fixed volume of hexane, the amount of released active ingredient was obtained by calculating the difference between the initial loading value and the clomazone amount measured in the supernatant normalized by the microparticle concentration after 1, 5, 15, 30 and 60 minutes. Results are shown in Table 3.

[0151] Table 3. Clomazone releasing profile.

[0152]

[0153] P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0154]

[0155] Example 2 Preparation of the microparticle of the invention

[0156] Firstly, a Mixture 1 was prepared as follows.

[0157] Sodium alginate Algogel 3001 was added in distilled water to obtain a 4% (w / w) dispersion under continuous agitation over night at room temperature. 49.7 g of dispersion were weighted in a separate beaker and 3 g of CaHPO4 were added; the mixture was homogenized by an Ultraturrax T50, at T104 rpm for 10 minutes (Mixture 1). The droplet size of the internal phase was monitored by optical microscopy.

[0158] Then a Mixture 2 was prepared as follows:

[0159] An O / W emulsion of clomazone (Sipcam-Oxon, Pero, Italy) as oil phase was prepared in parallel (ratio 1 :50 by weight). The water phase was constituted by 2% (w / w) solution of succinic, 0.2 % (w / w) of tween 80, 0,1 % (w / w) of Amepon WA (Azelis, Cusago, Italy) as wetting agent, and 0.2% (w / w) of Amepon MNS / 88 (Azelis, Cusago, Italy). The mixture was kept under agitation for 5 minutes at T 104 rpm and finally the pH was adjusted to 5.5 by adding ammonium hydroxide dropwise (Mixture 2).

[0160] 500 ml of Mixture 2 were added to Mixture 1 under agitation at 400 RPM for 5 minutes and subsequently pumped into a Buchi B-290 spray dryer (Buchi Italia s.r. I. , Cornaredo, Italy).

[0161] A summary of the feed composition and the spray dryer parameter settings are described in Table 4 and Table 5, respectively.

[0162] Table 4. Spray dried feed composition.

[0163]

[0164] P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0165]

[0166] Table 5. Spray dried parameter settings.

[0167]

[0168] The loading of clomazone within the dry powder was found to be 17.1% (w / w) by HPLC.

[0169] As evident from above, the use of alginate in the inventive process allowed to encapsulate the active ingredient in high amount and in effective way.

[0170] In the preferred embodiment of the invention when the active ingredient is clomazone, that is a problematic active ingredient being an organic liquid, the encapsulation was effective.

[0171] Example 3 Preparation of the microparticle of the invention

[0172] Firstly, a Mixture 1 was prepared as follows.

[0173] Sodium alginate Algogel 3001 was added in distilled water to obtain a 5% (w / w) dispersion under continuous agitation over night at room temperature. 47.4 g ofP024104WG-01 Notarbartolo & Gervasi S.p.A.

[0174] dispersion were weighted in a separate beaker and 0.5 g of CaHPO4 were added; the mixture was homogenized by an Ultraturrax T50, at 9 103rpm for 10 minutes (Mixture 1). The droplet size of the internal phase was monitored by optical microscopy.

[0175] Then a Mixture 2 was prepared as follows:

[0176] An O / W emulsion of clomazone (Sipcam-Oxon, Pero, Italy) as oil phase was prepared in parallel (ratio 1 :50 by weight). The water phase was constituted by 2% (w / w) solution of succinic, 2 % (w / w) of tween 80, 2 % (w / w) and 1.5% of L-leucine (Sigma-Aldrich, Schnelldorf, Germany) The mixture was kept under agitation for 5 minutes at T104rpm and finally the pH was adjusted to 5.4 by adding ammonium hydroxide dropwise (Mixture 2).

[0177] 500 ml of Mixture 2 were added to Mixture 1 under agitation at 400 RPM for 5 minutes and subsequently pumped into a Buchi B-290 spray dryer (Buchi Italia s.r. I. , Cornaredo, Italy).

[0178] A summary of the feed composition and the spray dryer parameter settings are described in Table 6 and Table 7, respectively.

[0179] 7% (w / w) of Amepon WA (Azelis, Cusago, Italy) as wetting agent, and 3% (w / w) of Amepon MNS / 88 (Azelis, Cusago, Italy) were then added a mechanically mixed to the fine powder obtained.

[0180] Table 6. Spray dried feed composition.

[0181]

[0182] P024104WG-01 Notarbartolo & Gervasi S.p.A.

[0183]

[0184] Table 7. Spray dried parameter settings.

[0185]

[0186] The loading of clomazone within the dry powder was found to be 1.7% (w / w) by HPLC. Particle size analyses were obtained by a laser diffraction analyzer (Malvern 3000, Malvern Panalytical, Malvern, UK) using water as dispersing medium, d50 and d90 obtained were 19.7 and 51.2 pm respectively.

[0187] Clomazone release from the alginate based microparticles analyses were performed by dispersing a known weight of powder in a fixed volume of hexane, the amount of released active ingredient was obtained by calculating the difference between the initial loading value and the clomazone amount measured in the supernatant normalized by the microparticle concentration after 1, 5, 15, 30 and 60 minutes. Results are shown in Table 8.

[0188] Table 8. Clomazone releasing profile.

[0189]

[0190] Efficacy and phytotoxicity evaluations were also performed in glasshouse in order to evaluate the selectivity on oilseed rape (Delight variety, OSR) and com (PR36Y03 variety). Echinochloa crus-galli (ECHCG), weed was used as target species and theP024104WG-01 Notarbartolo & Gervasi S.p.A.

[0191] formulation was compared against untreated sample pots and clomazone emulsifiable concentrates (EC, 500g / l). The dose applied for corn was 80 g / ha whereas 90 g / ha were chosen for oilseed rape treatment. The application took place just after the sowing of 15 seeds / container, and phytotoxicity symptoms (bleaching) had been evaluated for 14 days. From the date recorded during the whole trial period, it was observed that all the test items showed a significantly different bleaching profile as depicted in Figures 1 and 2.

[0192] More in detail, figures 1 A and 1 B show the appearance of untreated sample pots of both com and OSR respectively: no bleaching or other signs of toxicity were detected during the whole test. In figures 1 C and 1 D are shown the com pots treated by the emulsifiable concentrate and alginate based microparticles respectively. The difference between the samples was evident in terms of both bleaching and plant height. A similar result has also been obtained in OSR samples; the emulsifiable concentrate treated plants (1E) resulted smaller and whitened plants whereas the alginate capsule treatment did not significantly alter the samples (1F).

[0193] The graph in figure 2 confirms the lower toxicity of the formulation described above on the test cultures. The bleaching value on com samples treated by the EC resulted 70.0% whereas the toxicity value from the alginate-based formulation was substantially lower (26.3%, white bars). The same trend was observed on the ORS treated pots; in fact, the amount of bleached sample was 60.3% on the EC treated plants and 5.0% on the capsule treated case (grey bars).

[0194] Finally, the black bars represent the efficacy of both formulations on ECHCG culture. The EC formulation showed complete effectiveness on the target culture. Such value was reduced when alginate-based formulation was employed (77.1%). However, the efficacy reduction had a minimal effect on the final aim of the study since the aforesaid value was adequate for weed growth controlling as evident from the pictures. As evident from the figures, the use of alginate in the inventive process allowed to encapsulate the active ingredient in high amount and in effective way as well as to properly eradicate the weed growth process with negligible effects on crop cultures.P024104WG-01 Notarbartolo & Gervasi S.p.A.

[0195] Biodegradability

[0196] The aqueous biodegradation test was performed according to procedure described in ISO 14851 (2019), Annex A. The ThOD (Theoretical Oxygen Demand) was calculated from the chemical formula reported on the same procedure. The results are given in g / g. The test was also accomplished following the OECD Guideline for Testing of Chemicals 301 F - Manometric Respirometry Test (1992). The results of this test can be used to comply with the commission Regulation 2023 / 2055 of 25 September 2023 amending Annex XVII to Regulation (EC) No 1907 / 2006 of the European Parliament and of the Council concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) as regards synthetic polymer microparticles.

[0197] The sample for the test was obtained as described below:

[0198] Firstly, a Mixture 1 was prepared as follows.

[0199] Sodium alginate Algogel 3001 was added in distilled water to obtain a 5% (w / w) dispersion under continuous agitation over night at room temperature. 47.4 g of dispersion were weighted in a separate beaker and 0.5 g of CaHPO4 were added; the mixture was homogenized by an Ultraturrax T50, at 9-103 rpm for 10 minutes (Mixture 1 ). The droplet size of the internal phase was monitored by optical microscopy.

[0200] Then a Mixture 2 was prepared as follows:

[0201] A water solution was constituted by 2% (w / w) solution of succinic acid, 2 % (w / w) of tween 80, 2 % (w / w) and 1.5% of L-leucine (Sigma-Aldrich, Schnelldorf, Germany) The mixture was kept under agitation for 5 minutes at T104 rpm and finally the pH was adjusted to 5.4 by adding ammonium hydroxide dropwise (Mixture 2).

[0202] 500 ml of Mixture 2 were added to Mixture 1 under agitation at 400 RPM for 5 minutes and subsequently pumped into a Buchi B-290 spray dryer (Buchi Italia s.r.l., Cornaredo, Italy).

[0203] After 28 days, as measured by CO2 production, reference item sodium acetate has reached a biodegradation percentage of 91.2% (figure 3) As such the 60% pass level for a valid test was achieved. The biodegradation of alginate microparticles has shown an absolute biodegradation 88.4% reaching the 60% biodegradability requirement to comply with REACH regulation (figure 4).P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0204] Example 4 Preparation of the microparticle of the invention

[0205] Microparticles containing bixolozone as encapsulated Al were obtained following the procedure described above. Bixolozone is a highly volatile liquid herbicide characterized by a high vapor tension, hence a significant volatility. The need to achieve an Al controlled release for optimum effectiveness as well as the reduction of side effects such as crop toxicity and drifting is necessary. The emulsion was obtained at 90°C to let the bixlozone to be in liquid form. A summary of the feed composition and the spray dryer parameter settings are described in Table 9 and Table 10, respectively.

[0206] Table 9. Spray dried feed composition.

[0207]

[0208] Table 10. Spray dried feed composition.

[0209]

[0210] The loading of bixlozone within the dry powder was found to be 28.9% (w / w) by HPLC. D50 and d90 obtained were 8.9 and 34.2 pm respectively.P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0211] Bixlozone percent release from the alginate based microparticles is shown in table 11

[0212] Table 11. Bixlozone releasing profile.

[0213]

[0214] Example 5 Preparation of the microparticle of the invention

[0215] Microparticles containing lambda cyhalothrin as encapsulated Al were obtained following the procedure described above. 1. Lambda cyhalothrin is a pyrethroid insecticide harmful to humans because of its severe side effects. The encapsulation of lambda cyhalothrin in a confined system is mandatory in several manufacturing processes to protect either employers or final users. The emulsion phases were kept at 60°C to let the lambda cyhalothrin to be in liquid form.

[0216] A summary of the feed composition and the spray dryer parameter settings are described in Table 12 and Table 13, respectively.

[0217] Table 12. Spray dried feed composition.

[0218]

[0219] P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0220]

[0221] Table 13. Spray dried feed composition.

[0222]

[0223] The loading of lambda cyhalothrin within the dry powder was found to be 28.9% (w / w) by HPLC. D50 and d90 obtained were 15.0 and 43.8 pm respectively.

[0224] Lambda cyhalothrin percent release from the alginate based microparticles is shown in table 14

[0225] Table 14. Lambda cyhalothrin releasing profile.

[0226]

[0227] Example 6 Preparation of the microparticle of the inventionP024104WO-01 Notarbartolo & Gervasi S.p.A.

[0228] Microparticles containing triallate as encapsulated Al were obtained following the procedure described above. 1. Triallate is a herbicide belonging to the thiocarbamate class and it needs to be finely released from capsules to carry out a proper weed control with no side effect. The emulsion phases were kept at 40°C to let the triallate to be in liquid form.

[0229] A summary of the feed composition and the spray dryer parameter settings are described in Table 15 and Table 16, respectively.

[0230] Table 15. Spray dried feed composition.

[0231]

[0232] Table 16. Spray dried feed composition.

[0233]

[0234] The loading of triallate within the dry powder was found to be 12.5% (w / w) by HPLC. D50 and d90 obtained were 13.9 and 27.4 pm respectively.P024104WO-01 Notarbartolo & Gervasi S.p.A.

[0235] Triallate percent release from the alginate based microparticles is shown in table 17.

[0236] Table 17. triallate releasing profile.

[0237]

Claims

1. P024104WO-01 Notarbartolo & Gervasi S.p.A.CLAIMS1. A process for the preparation of a water dispersible dry microparticle, wherein said water dispersible dry microparticle encapsulates at least one active ingredient, said process comprising the step of:a) preparing a dispersion of an alginate of a monovalent cation selected from an alkali metal and ammonium by adding the alginate of the monovalent cation to water; b) adding a metal salt to the dispersion of step a) thus obtaining a Mixture 1 ; c) preparing a Mixture 2 of at least one active ingredient;d) Adding Mixture 2 to Mixture 1 thus obtaining a feed composition;e) spray-drying the feed composition, thus obtaining the microparticles encapsulating the at least one active ingredient.

2. The process according to claim 1 , wherein Mixture 2 is an oil / water emulsion.

3. The process according to claim 1 or claim 2, wherein the at least one active ingredient is selected from the group consisting of- a thiocarbamate herbicide, preferably triallate, diallate, butylate, cycloate, EPTC, molinate;a isoxazoline-derivate herbicide, preferably clomazone, bixolozone, pyroxasulfone, fenoxasulfone;-a pyrethroid, preferably cyfluthrin, lambda-cyhalothrin, bifenthrin, permethrin, resmethrin;- a dinitroaniline, preferably pendimethalin, trifluralin, ethalfluralin, oryzalin, butralin, benefin / benfluralin and prodiamine;- a terpen and / or terpeoid, preferably d-limonene, azadirachtins, carvacrol, 1,8-cineole, anisole, limonene, [3-pinene, linalool, menthone, a-pinene, pulegone, myrcene eugenol, borneol, menthol, isomenthol, anethole, camphor, carvone, menthyl acetate, linalyl acetate, thymol, p-cymene, y-terpinene, a-terpineol, 4-terpineol, citronellol, geraniol; and- an essential oil, preferably cinnamon oil, citronella oil, clove oil, eucalyptus oil, lemongrass oil, mint oil, mint oil, orange oil, peppermint oil, rosemary oil, thyme oil.27P024104WO-01 Notarbartolo & Gervasi S.p.A.

4. The process according to anyone of claim 1-3, wherein the at least one active ingredient is a highly volatile liquid compound, preferably an herbicide selected from the group consisting of clomazone, bixolozone, pyroxasulfone and fenoxasulfone, still more preferably clomazone.

5. The process according to anyone of claims 1-4, wherein the at least one active ingredient has a low solubilization rate.

6. The process according to anyone of claims 1 -5, wherein in step c) a wetting agent is added in the presence of a surfactant agent.

7. The process according to anyone of claims 1 -6, wherein the dispersion of step a) comprises sodium alginate as alginate of a monovalent cation, preferably in the range from 2 to 10% (w / w), more preferably 4% (w / w) with respect to the total weight of the dispersion.

8. The process according to anyone of claims 1 -7, wherein the metal salt of step b) can be selected from CaHPCU, Ca tartrate, Calcium oxalate, CaCOs, Barium oxalate, BaCOs, ZnCOs, Zn2(PO4)3, MnCOs, Mns(PO4)2 preferably the metal salt is calcium hydrogenphosphate (CaHPCU).

9. The process according to anyone of claims 1 -8, wherein the Mixture 2 of at least one active ingredient comprises also at least one hydrophobic amino acid based compound.

10. The process according to anyone of claims 1-9, wherein the amount ratio of Mixture 2 to Mixture 1 in the adding step d) is in the range from 1:1 to 1 :3, preferably 1:1.

11. The process according to anyone of claims 1 -10, wherein in step d) Mixture 2 is added to Mixture 1 under agitation.

12. The process according to anyone of claims 1-11, wherein said spray-drying step e) is carried out, independently each other, according to the following parameters: - an inlet temperature from 120 to 170, preferably 140°C;- an atomizing gas rate from 7 to 11 L / min, preferably 10 L / min.- an aspiration rate from 60 to 100%, preferably 70%.- a feed pumping rate from 2 to 5 m l / min, preferably 3.4 m l / min.P024104WO-01 Notarbartolo & Gervasi S.p.A.

13. The process according to claims 1-11, wherein the loading of the encapsulated active ingredient in the microparticle is in the range of 5 to 30% w / w.

14. A water dispersible dry microparticle obtainable from the process according to claim 1-13, wherein the active ingredient is a highly volatile liquid compound, 15. The water dispersible dry microparticle according to claim 14, wherein the active ingredient is clomazone and preferably the encapsulated clomazone is in amount from 5 to 30%, preferably 13 to 17% w / w, with respect to the total weight of the microparticle.

16. A use of the water dispersible dry microparticle according to claim 14 or 15 to deliver an active ingredient in agriculture field.

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