METHOD AND PROCEDURE FOR OBTAINING HIGHLY STABILITY NATURAL PYRETHRIN MICROBIOCAPSULES

Abstract

The present invention describes a process for obtaining microcapsules of one or more pyrethrins as the active substance, and falls within the field of biopesticide production technology. Natural pyrethrin is a broad-spectrum insecticide extracted from the flowers of plants of the genus Chrysanthemum and is readily decomposed by air and light. The present invention increases the stability of pyrethrins, making them effective for a longer period than other prior art solutions. The method and process comprise the following steps: an oil phase, an emulsification phase of the mixture, and an encapsulation phase. The result is the production of pyrethrin microcapsules with a size between 0.5 and 5 microns, exhibiting greater stability. The process does not reduce the insecticidal capacity of the pyrethrins.

Description

METHOD AND PROCEDURE FOR OBTAINING HIGHLY STABILITY MICROBIOCAPSULES OF NATURAL PYRETHRINS TECHNICAL SECTOR The invention belongs to the field of application of the chemical industry sector dedicated to the production of nanobiopesticides, and specifically to methods of production of pyrethrin nanoemulsions. BACKGROUND OF THE INVENTION With societal development and the expansion of agricultural areas, there has been a demand for new, more efficient and safer pesticides. Some highly effective chemical formulations have emerged rapidly, but crop analysis reveals high levels of residues. However, with the development of certification and environmental awareness, along with advances in biotechnology in recent years, pesticide manufacturers have begun to comply with safety, efficiency, circular economy, and ease-of-use guidelines, resulting in non-toxic, environmentally friendly, and zero-residue products. Biopesticides have become a priority for the agrochemical industry. The use of natural pyrethrins as a pesticide has a long history and can be used to control pests that affect both humans and crops. Natural pyrethrin is an insecticide extracted from the flower of the pyrethrum (Chrysanthemum cinerariaefolium) and is easily degraded by light, air, water, and microorganisms. Pyrethrin is highly toxic to crop-damaging insects but is safe for animals, is non-polluting, and leaves no residue. For pest prevention and control, pyrethrins are usually found in solid form, as oils, wettable powders, and emulsifiable concentrations. Pyrethrum oil and concentrated emulsions are often mixed with plant-derived substances, which are pollutants for water and the environment. Encapsulating pyrethrins not only allows for lower doses but also protects the environment, reduces production costs, increases the insecticide's effectiveness when used with other inputs or pesticides, and masks the unpleasant odor associated with insecticidal activity, making them suitable for pest control. BRIEF DESCRIPTION OF THE INVENTION The present invention has been designed so as to provide, according to a first aspect thereof, a procedure for obtaining microcapsules of one or more pyrethrins as the active substance, said procedure comprising three steps: 1. Preparation of oil phase, which consists of a solution of one or more pyrethrin(s) as the active substance with a purity between 48%-80%, in one or more vegetable oil(s) in a 1:20 ratio, optionally agitation is produced, optionally a solvent agent can be added which can be fatty acid(s), alcohol(s), essential oil(s) or a mixture of the above, then agitation is applied to the mixture. 2. Emulsifying phase where an emulsifier and optionally a stabilizing agent and / or a preservative are added under agitation. Additionally, co-formulating agent(s) with antioxidant, preservative, and / or antifoaming properties may be added. 3. Microcapsule production phase, where through a mixing process, preferably using a mixer, such as a mixer with a paddle agitator, the result is the production of pyrethrin microcapsules at 4-25% w / v, preferably between 4-8% w / v with a size of between 0.5 and 5 microns, with greater stability. In the present invention, pyrethrin microcapsule refers to; micrometric particles with an external membrane comprising pyrethrin as the active substance. In phase (1) one or more vegetable oil(s) are added, which are selected from the group consisting of sunflower, corn, soybean, avocado, jojoba, pumpkin, grapeseed, sesame, hazelnut, glycerol triprocaprylate, or vegetable oils of formula R9 COOR10, in which R9 represents the residue of a higher fatty acid comprising 7 to IVIA / a / ZUZ l / U 14U II carbon atoms and R 10 represents a linear or branched hydrocarbon chain containing 3 to 30 carbon atoms, in particular alkyl or alkenyl, undecylenic, myristoleic, palmitoleic, oleic, linoleic, linolenic, ricinoleic, eicosenoic, or docosenoic acids (found in pine, corn, sunflower, soybean, raisin seeds, flax, or jojoba). Preferred examples of fatty acids include those comprising unsaturated molecules, such as oleic acid, which is oligomerized by a condensation reaction of the double bonds. This reaction results in mixtures comprising essentially dimers and trimers. Fatty acid dimers and trimers are understood to be oligomers of two or three identical or different monomers. Advantageously, these fatty acids, saturated or unsaturated, comprise 12 to 100 carbon atoms, and even more advantageously 24 to 90. In phase (1) the agitation is between 60-150 RPM In phase (1) the temperature is 20 to 40sC, preferably between 25-35sC. In phase (1) a solvent agent selected from the unsaturated fatty acids and their derivatives can be added: linoleic acid, linoleic acid, oleic acid, folic acid and their derivatives, ubiquinone and ubiquinol and their derivatives, tocopherols and derivatives In phase (1) a solvent agent selected from lower alcohols such as ethanol and isopropanol; polyhydroxylated alcohols such as glycerol, propylene glycol, dipropylene glycol and sorbitol can be added; In phase (1) a solvent agent selected from natural or synthetic essential oils can be added, such as, for example, eucalyptus, lavender hybrid, spike lavender, vetiver, litsea cubeba, lemon, sandalwood, rosemary, chamomile, savory, nutmeg, cinnamon, hyssop, caraway, orange, geranium, juniper, and bergamot oils. In phase (2) a non-ionic emulsifying agent is added which appears in a proportion of 10 to 50% of the composition by weight, and preferably between 15 to 30% by weight with respect to the total weight of the composition. IVIA / a / ¿U¿ l / U 14U II Non-ionic emulsifying agents are defined as amphoteric, anionic, and preferably cationic. Amphoteric or ampholytic emulsifying agents are defined as surfactants that contain, in addition to an alkyl or acyl group with 8 to 18 carbon atoms, at least one free amino group and at least one -COOH or -SO3H group in the molecule, and are suitable for the formation of internal salts. Examples of suitable ampholytic surfactants include N-alkylglycines, N-alkylpropionic acids, N-alkylaminobutyric acids, N-alkyliminodipropionic acids, N-hydroxyethyl-N-alkylamidopropylglycines, N-alkyltaurines, N-alkylsarcosines, 2-alkylaminopropionic acids, and alkylaminoacetic acids, each with approximately 8 to 18 carbon atoms in the alkyl group.Anionic emulsifying agents are understood to be those that have a negative charge. Examples of anionic surfactants include alkyl sulfates with a chain length of 8 to 18 carbon atoms, alkyl or alkylaryl ether sulfates with 8 to 18 carbon atoms in the hydrophobic residue and up to 40 units of ethylene oxide or propylene oxide, alkyl or alkylaryl sultanates with 8 to 18 carbon atoms, esters and semi-esters of sulfosuccinic acid with monovalent alcohols or alkylphenols, alkyl or alkylaryl sultanates, hydroxylalkanol sulfates, saturated and unsaturated chain fatty acids of 8 to 24 carbon atoms and their oxy-alkylated esters, and polyethoxylated alkanol sulfates and phosphates. Cationic emulsifying agents are understood to be those that contain a positive charge in aqueous solution, amines and also quaternary compounds.Examples of cationic emulsifying agents include alkylamines with 7 to 25 carbon atoms, N,N-dimethyl-N(hydroxyalkylammonium) salts with 7 to 25 carbon atoms, mono- and di(with 7 to 25 carbon atoms)-alkyldimethylammonium compounds quaternized with alkylating agents, ester quats such as mono-, di- or quaternary esterified trikanolamines, which are esterified with carboxylic acids with 8 to 22 carbon atoms, and imidazolin quats such as 1-alkyl-imidazolium salts of general formulas I or II. In phase (2) the cationic emulsifying agent used is a quaternary compound, it is observed that it increases the insecticidal capacity of the product resulting from the described procedure. In phase (2), eventually, a second emulsifying agent can be added. When using combinations of emulsifying agents, it is advantageous to use a relatively hydrophobic emulsifying agent in combination with a relatively hydrophilic agent, or to use an anionic emulsifying agent in combination with a non-ionic agent. In phase (2) a second emulsifying agent present in the composition can be added, generally in a proportion that can range from 10 to 50% by weight and, preferably, 15 to 30% by weight with respect to the total weight of the composition. In phase (2) additionally, one or more co-formulating agents may be added, which may be selected from antioxidants such as tocopherol and propyl gallate, nitroxides, BHT-butylhydroxytoluene, BHA-butylhydroxyanisole, and / or acidulants such as citric acid, lactic acid and malic acid, hydrochloric acid, tartaric acid, phosphoric acid, lactic acid, sulfonic acid, and / or antifoaming agents; a fatty acid containing at least 14 to 24 carbon atoms, silicone-based or fluorine-based. In phase (2) the temperature is between 10-459C, preferably between 25-35sC. In phase (3), agitation occurs at 60-300 RPM for 1 to 36 hours, preferably 1 to 4 hours. The process was carried out under controlled conditions of density between 0.9100.980 g / cm³ and pH between 5-10, preferably 6.5-8.5. The final result of the described procedure is the production of pyrethrin microcapsules with a size between 0.5-5 µm, a regular morphology, and a smooth surface. In another aspect, the present invention relates to the use of the microcapsules of the present invention as an insecticide. More particularly, the present invention relates to the use of the microcapsules of the present invention for the control of arthropod pests such as insects, preferably aphids and ants. The efficacy of the insecticidal product obtained by this process lasts for up to two years. BRIEF DESCRIPTION OF THE DRAWINGS To complement the description being made and to aid in a better understanding of the characteristics of the invention, a set of drawings is included as an integral part of said description, which, for illustrative and non-limiting purposes, show IVIA / a / ¿U¿ l / U 14U II has represented the following: Figural - Shows a chromatographic profile of the resulting composition under normal conditions and 14 days later on the same compound applying the MT 46.3 method Figure 2 shows a photograph of pyrethrin microcapsules observed under an epifluorescence microscope (Axioplan, ZEISS). A drop of sample is placed on a slide (20x40x0.25mm) with a 20x objective. Figure 3 - Shows a photograph of pyrethrin microcapsules indicating their size and monodispersity: 1. Length 5.14 pm 2. Longitude 4.42 pm 3. Length 5.48 pm 4. Length 5.14 pm PREFERRED EMBODIMENT OF THE INVENTION The invention will now be illustrated by means of tests carried out by the inventors, which demonstrate the effectiveness of the invention's procedure: Example 1 73g of a refined chrysanthemum extract EDEOIL P60® were mixed as a source of pyrethrins 60% (w / w); Pyrethrin I, Cinerin I, Jasmolin I, Pyrethrin II, Cinerin II and Jasmolin II, the ratio between Pyrethrin I and Pyrethrin II was 1.85, with 557g of soybean oil with 50% linoleic acid and 25% oleic acid, also containing lauric, myristic, palmitic, stearic and linolenic acid, agitation was carried out at 60rpm in Hl 180x-2® at a temperature of 25SC and 1g of tocopherol rich extract E306 was added, agitation was continued for 20 minutes, then without stopping the agitation 158g of propylene glycol at 99.5% and 185g of polysorbate 80 at 97% Sorbilene® were added. Next, 15g of 94% purity D-limonene (bitter orange) and 8g of vegetable glycerin E-422 were added, acting as a co-formulant to improve the surfactant activity of the formulation.It was shaken at 120 rpm for about 2 hours and the appearance of the microcapsules was observed (Figure 2), then the microcapsules and their shapes were measured according to (Figure 3). IVIA / a / ZUZ l / U 14U II Example 2 To determine the stability of the product obtained by the procedure of the present invention as described in Example 1, method MT 46.3 (J. Zhang et al. J. of Chromatography A. 1218 (2011) 6621-6629 Dean Ban et al. Afr. J. of Biotechnology Vol. 9 (18), pp. 2702-2708, 3 May, 2010) was used by heat stimulation to age the formulations and simulate the packaged and stored product (Figure 1). The formulations that passed the test were considered viable for at least 2 years. TABLE I iviA / a / ¿u¿ ι / υ 14U11 Storage stability at 54°C: Test 0 days 7 days 14 days Physical state (Met. EPA OPPTS 830.6303) Homogeneous liquid Homogeneous liquid Homogeneous liquid Color (Met. EPA OPPTS 830.6302) Transparent yellow Transparent yellow Transparent yellow Odor (Mét. EPA OPPTS 830.6304) Characteristic Characteristic Characteristic pH 1 / 100 (20°C) (Met. CIPAC MT75.3) 4.66 4.61 4.57 Density (25°C) (Met. EPA OPPTS 830.7300) 1.0390 g / mL 1.0392 g / mL 1.0386 g / mL Acidity (% H2SO4) (CIPAC Method MT 191) 0.063 0.065 0.068 Wettability (CIPAC MT 53.3 Method) < 10 sec. < 10 sec. < 10 sec. Suspensibility (CIPAC MT 184 Method) 96.8 96.2 95.8 Foam persistence (mL in 1 minute) (CIPAC MT 47 Method) < 2 mL < 2 mL < 2 mL Chemical Composition: Pyrethrins (HPLC-DAD Method) 4.48% w / v 4.48% w / v 4.48% w / v

Claims

1. A process for obtaining pyrethrin microcapsules comprising several steps: (1) Oil phase, consisting of a solution of one or more pyrethrin(s) as the active substance with a purity between (48%-80%), in one or more vegetable oil(s) in a 1:20 ratio; (2) Emulsifying phase in which an emulsifier is added; (3) Microcapsule obtaining phase, in which pyrethrin microcapsules at 4-25% w / v are obtained by means of a controlled mixing process.

2. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (1), the animal or vegetable oils are selected from the group consisting of sunflower, corn, soybean, avocado, jojoba, pumpkin, grapeseed, sesame, hazelnut, fish oils, glycerol triprocaprylate, or vegetable or animal oils of the formula Rg COOR10 wherein R9 represents the residue of a higher fatty acid comprising 7 to 29 carbon atoms and R10 represents a linear or branched hydrocarbon chain containing 3 to 30 carbon atoms, particularly alkyl or alkenyl.

3. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in phase (1), where agitation occurs, the speed is between 60-150 RPM.

4. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in phase (1), the temperature is 20 to 40eC.

5. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (1), a solvent agent such as fatty acids and their derivatives can be added.

6. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (1), a solvent agent such as lower alcohols can be added. IVIA / a / ZUZ l / U 14U II 7. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (1), a solvent agent such as natural or synthetic essential oils can be added.

8. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (1), a solvent agent can be added which may be a mixture of claims 5, 6 and / or 7.

9. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (2), a non-ionic emulsifying agent is added which appears in a proportion of 10 to 50% of the composition by weight with respect to the total weight of the composition.

10. In claim 9 the non-ionic emulsifying agent that is added is of the amphoteric or ampholytic type.

11. In claim 9 the non-ionic emulsifying agent that is added is of the anionic type.

12. In claim 9 the non-ionic emulsifying agent that is added is of the cationic type.

13. In claim 9, a second relatively hydrophobic emulsifying agent can be added in combination with a relatively hydrophilic agent.

14. In claim 13 the emulsifying agent is anionic in combination with a non-ionic agent.

15. In claim 13 the emulsifying agent is present in the composition, generally, in a proportion that can range from 10 to 50% by weight.

16. In claim 9, a co-formulating agent may be added.

17. In claim 16 the co-formulating agent may be an antioxidant.

18. In claim 16 the co-formulating agent may be an acidulant.

19. In claim 16 the co-formulating agent may be an antifoaming agent.

20. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in phase (2), the temperature is between 10°C and 45°C.

21. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in phase (3), agitation of 60300 RPM occurs between 1 and 36 hours.

22. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (3), it is produced at a density between 0.91 Og / cm3 and 0.980g / cm3.

23. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in phase (3), a pH between 510 is produced.

24. A process for obtaining pyrethrin microcapsules according to claim 1, characterized in that in step (3), microcapsules of a size between 0.5μ and 5μ are produced.

25. The use of the encapsulated product resulting from the procedure according to claim 1, for pest control.

26. The use according to claim 25, is an insecticide.

27. The use according to claim 26, is a pyrethroid.

28. Use in accordance with claim 25, with an optimal effectiveness durability of at least 2 years 29. A use according to claim 25 wherein the emulsifier added in Phase (2) is a cationic emulsifying agent that increases the insecticidal capacity.