IT202100014189A1 - POLYETHYLENE SUPPORT TO WHICH A HYDROGEL LOADED WITH A NATURAL PESTICIDE ACTIVE INGREDIENT IS BOUND - Google Patents

Description

Polyethylene support which ? bound a hydrogel loaded with a natural antiparasitic active ingredient

Field of invention

The present invention relates to an antiparasitic product comprising a polyethylene support in the form of a net or fabric, covalently bonded with a composition comprising a polymer in the form of a hydrogel and plant extracts and/or their active components, optionally microencapsulated.

The present invention also relates to a process for impregnating a polyethylene support with this composition, and to the use of said support, preferably in the form of a fabric, impregnated for the protection of humans, plants and other objects from insects.

State of art

Insecticides, fungicides and repellents are generally administered by spray (insecticides, biocides or fungicides) or locally (biocides and repellents).

However, their use has a negative effect on the environment (pesticide sprays) by increasing environmental pollution or, when biocides are used in contact with the skin (body repellents), by increasing possible negative dermal effects such as sensitization and allergy. To minimize these drawbacks, the active ingredient alone or encapsulated can be impregnated on a support such as nets and fabrics to act against harmful insects in agriculture and for humans.

In particular, nets and fabrics can be used alone or possibly linked with compositions capable of absorbing and releasing active substances and used in various applications, avoiding physical contact of pesticides with humans and at the same time reducing their negative environmental impact. US6896892 discloses an insecticide-impregnated fabric capable of killing and repelling disease vectors after repeated washing. The fabric? impregnated with an insecticidal composition containing an insecticide, a cyclodextrin and a binding agent represented by a polymeric binding agent.

US2007/0292464 discloses fibers and sheet fabrics on which there are microencapsulated insect repellent mixtures and binders, in which the microcapsule ? formed by cellulose, gelatin, phospholipids and chitosan and the binders formed by a polymer capable of creating a binding film, such as polyurethane, polyvinyl acetate, polymer melamine, polysiloxane.

US2005/0132500 describes an insecticide composition for application on a textile material comprising at least one insecticide and/or at least one repellent and at least one binder so as to obtain an impregnation of the active substances on the textile surface capable of resisting washing.

WO2008/151984, WO2010/012671 and WO20111/001037 disclose a method for impregnating textile material and nets, and their use in agricultural applications.

The use of insecticide-containing tissue nets as tools against malaria? described in many patent applications, and such fabrics are also already? marketed. Are they citing, for example, Trinet? of BASF and Olyset? by Sumitomo.

Other techniques have also been used to incorporate the active ingredients into the Polypropylene or Polyethylene fibers and then weave the nets or fabric. Examples are disclosed in WO2010/015257 and WO2010/046348.

WO2006 / 117702 describes microcapsules for textile materials containing an active product (fragrance, essential oil, antibacterial, phase change material) equipped with reactive groups capable of chemically binding the microcapsules to the fibres.

A method for functionalizing a textile substrate through the preparation of an envelope formed by materials capable of binding to the fibers when subjected to ionizing radiation and containing microcapsules, ? described in WO2008/099090.

The use of a hydrogel polymer dressing impregnated with silver nanoparticles and capable of impregnating active substances? described in WO2018/055203.

A functionalized fabric for medical use, in which the functionalization of the fabric? obtained by treating glycidyl methacrylate or glycerol derivatives in order to create a substrate capable of being impregnated with active bactericides ? described in EP2182931.

A PE support in the form of a mesh or fabric, covalently bonded with a hydrogel forming polymer capable of absorbing active substances selected from the pyrethroid class? described in EP3397055.

? also known is the use of natural active ingredients as insecticides, by direct application on the crops to be protected. However, this type of application has limitations, since the natural insecticides applied have poor stability? and a limited time of action, due to the dispersion in the environment induced by the action of the wind and, above all, due to the degradation of their function by sunlight.

Technical problem

All the methods for the preparation of nets or fabrics with antiparasitic active ingredients just described and others known in the state of the art have many drawbacks, such as the complexity? in the preparation, the presence of active substances dangerous for the environment such as synthetic insecticides, such as neonicotinoids, which are also dangerous for beneficial insects (bees and bumblebees), pyrethroids due to their high persistence in the environment with the possibility of soil and water contamination and consequently the strong limitations for their use in some European countries for agrochemical applications and, finally, the presence of substances potentially able to give sensitization reactions, such as synthetic repellents, for example DEET.

Furthermore, the prolonged use of synthetic active principles has the effect of developing in insects an ability to of resistance to the same principles, with the consequence that ever greater doses are necessary to maintain its insecticidal effectiveness.

The substances of natural origin known and used as insecticides, such as for example pyrethrum, used according to what is known in the state of the art, have good efficacy but a short duration, since they are subject to rapid photodegradation by sunlight.

Therefore, the problem of providing a support (a net or a fabric) that overcomes the limits linked to the embodiments known to the state of the art with reference to the environmental impact and the generation of resistance effects in the insect populations mentioned above remains unresolved. and, on the other hand, the problem of identifying a mode? application of insecticides based on natural principles which allows to avoid, or at least limit, the problems of loss of efficacy over time.

Purpose of the invention

Purpose of the invention? that of providing a support (for example a mesh or a fabric) which overcomes the limits associated with the embodiments known to the state of the art.

Brief description of the invention

The present invention achieves the set purposes, since it is a polyethylene support in the form of a net or fabric for use as an antiparasitic, on the surface of which a hydrogel is chemically bonded comprising polyvinylpyrrolidone and ethylene glycol dimethyl acrylate, said hydrogel being charged with at least one principle active ingredient selected from natural insecticides, natural fungicides, natural herbicides, natural repellents or their active components from plant extracts.

Detailed description of the invention

The present invention provides a support consisting of a polyethylene mesh or fabric on which chemically bonded a hydrogel comprising polyvinylpyrrolidone and ethylene glycol dimethyl acrylate (EGDMA), in which active substances selected from plant extracts and/or their active components with active insecticide and/or fungicide and/or repellent. In this way, the active substances are released slowly over time, in order to obtain the effectiveness of the treatment thus pursuing a reduction in doses and without possible contamination of the environment and/or negative effects on humans.

A second purpose of the present invention ? that of providing a method for impregnating this support with the active substances.

Another purpose of the present invention ? the use of such support in the form of a net or fabric for the protection of humans, plants and other assets.

The present invention provides a polyethylene support prepared according to what has already been described in EP3397055, whose teaching ? incorporated into this question by reference.

It is a polyethylene support in the form of a net or fabric which ? chemically bonded, a hydrogel comprising polyvinylpyrrolidone and ethylene glycol dimethyl acrylate.

The method for binding the hydrogel on said support comprises the steps of:

? immerse the support in a toluene solution containing ethylene glycol dimethyl acrylate (EGDMA) and cumene hydroperoxide;

? immerse the support in an aqueous solution containing: FeCl2*4H2O, ascorbic acid and polyvinylpyrrolidone

? wash and dry the support.

It is specified that, within the scope of the present description and in the subsequent claims, unless otherwise indicated, all the numerical expressions of quantities, percentage parameters and so on via, are to be understood preceded by the term "about" and that all the intervals of quantity? numerical include all possible combinations of maximum and minimum values and include all possible intermediate intervals, in addition to those specifically indicated.

The surface hydrogel cos? format ? between 1%% and 15% by weight (hydrogel weight/support weight), and preferably between 5 and 10%.

The support is washed with an alcoholic solvent, preferably ethanol or isopropanol. Ethanol or mixtures thereof with water are preferred. Especially favorite ? a solution formed by 50% ethanol and 50% water.

After the treatment, the support is dried at a temperature between 25 and 40°C for a period between 12 and 24 hours, possibly under forced air circulation. 30-35 ?C and 12 hours in forced air circulation are preferred.

In general, the term "pesticide" indicates products or mixtures thereof having insecticide, repellent, fungicide, herbicide, molluscicide. The term insecticide indicates products or their mixtures having insecticide, acaricide and miticide.

The term fungicide indicates products or mixtures thereof having fungicidal, microbicidal and virucidal, unless otherwise indicated in the context.

The term "repellent" refers to products or mixtures thereof which discourage insects or other pests from approaching or settling.

The term "herbicide" as used herein means products or mixtures thereof used to control unwanted plants

Nets or fabrics prepared according to the method just described are then treated with active products selected from:

? Natural insecticides or their active components from plant extracts.

By way of example but not limitation: pyrethrum extract from Tanacetum cinerariaefolium, bergamot oil, cinnamon oil, clove oil, citronella oil, cypress oil, eucalyptus oil, fennel oil, garlic oil, grapefruit, thyme oil, geranium oil, lavender oil, neem oil, orange oil, rosemary oil, manuka oil, peppermint oil, Alaskan yellow cedar oil, Clitoria ternatea oil, thyme, white cypress oil, allicin, azadirachtin, eucalyptus , thymol, ?-pinene, ? ? pinene, p-cymene, d-limonene, 1,8-cineole, citral, eugenol, geraniol, leptospermone, linalool, phellandrene, pyrethrins. Preferred are extracts of pyrethrum, thyme oil, clove oil, neem oil, thymol, azadirachtin, allicin, cineole 1,8, eugenol and d-limonene.

? Natural fungicides or their components from plant extracts.

Examples include geranium oil, geraniol, clove oil, eugenol, thyme oil, thymol, tea tree oil. Geranium oil, geraniol, eugenol, thymol are preferred.

? Natural herbicides or their active components from plant extracts.

By way of example clove oil, pine oil, pelargonic acid, Alternaria tenuis extract. Clove oil and pelargonic acid are preferred.

? Natural repellants or their components from plant extracts.

Examples include thyme oil, geranium oil, lavender oil, ginger oil, rosemary oil, peppermint oil, lemon eucalyptus oil, citronella oil, pinene, pinene geraniol, eucalyptus, eugenol. Thyme oil, geranium oil, lemongrass oil, peppermint oil, geraniol, eugenol, thymol and eucalyptol are preferred.

In one embodiment, the above mentioned products can be used in combination with pheromones (a factor that triggers a response in members of the same species), floral attractants to create a trap effect on harmful insects, so as to increase the chances of to kill them, substances known in the state of the art having a synergistic effect with that of pesticides.

How already? reported in the literature, for example in US9097152, US2009/0186096,

in Ind. Eng. Chem. Rev., 2008,47,4142-4147, the natural active ingredients or their active constituents can be used alone or encapsulated in suitable microcapsules such as polyurea, polyurea-polyurethane, polyester microcapsules.

Natural active ingredients or their active constituents can be used in combination with other products when there is the need? to stabilize the natural products present in the networks that can be degraded by light. In particular, the presence of pyrethrum extract and / or its components can? represent a problem for the short stay of the activity? biological nature of the mesh or fabric, due to its natural photodegradation.

To overcome the problem, photostabilizing products selected in the class of UV protection agents such as benzophenones and benzotriazoles can be added.

In general, the agents absorb, with two different mechanisms, the portion of light with a wavelength <350nm, which is responsible for photodegradation. Photodegradation occurs by promoting the formation of free radicals, which produce chain reactions by interacting with the chemical bonds of the active ingredient, degrading it completely. The photo stabilizers do s? that the portion of the light pi? energy or shorter wavelength is slowed down, allowing the survival of the active ingredients.

The polyethylene support can be loaded with the natural active ingredient or its constituents by immersion in an organic solution formed by ethanol, ethanol in water or water in which the active ingredient has previously been dissolved.

The appropriate solvent can be chosen on the basis of solubility? of natural active ingredients or their constituents.

The active ingredients may also be commercially available in other solvents. In this case, the solvent present in the commercial formulations must be previously diluted with ethanol or water according to their solubility characteristics. and vapor pressure.

Ethanol and a 1:1 (v:v) mixture of ethanol and water are preferred.

If natural active ingredients or their active constituents are used encapsulated in organic microcapsules, water is chosen as the solvent.

The meshes or fabric with the hydrogel surface formed by polyvinylpyrrolidone and EGDMA and containing between 1% and 10% by weight of hydrogel (hydrogel weight / support weight), are immersed in a solvent selected from ethanol and ethanol/water in which the natural active ingredients have been previously dissolved.

Based on the quantity? of hydrogel present on the surface, the quantity? of active substances ranges from 1% to 99% with respect to the weight of the hydrogel present. ? preferred a ratio between 20% and 99%, particularly preferred ? a ratio between 45% and 99%.

During the immersion the solution is stirred at 40-50 rpm, corresponding to 251-314 rad/min at 25-30?C for 8-24 hours. Different absorptions can be obtained depending on the immersion time under stirring. ? an absorption time of 12-20 hours is preferred.

Subsequently the nets or the fabric are dried in the air at 25-30 ?C under forced air circulation.

Impregnated nets or fabric can be used for various purposes. In particular, such impregnated nets or fabrics can be used for the protection of humans, animals or materials from harmful organisms. For example, they can be used as mosquito nets. The mosquito nets impregnated according to the present invention can be washed more quickly. times without a significant decrease in activity? of insect control.

For the protection of materials from harmful organisms, nets or fabrics can be wrapped around the material (or materials) to be protected. Examples of materials to be protected include crops and/or harvested crops such as e.g. bales of tobacco, woods, fruit trees, vineyards. Depending on the mode of installation the nets and fabrics can also have a use aimed at mitigating or influencing the effects of one or more? atmospheric or natural agents (rain, hail, snow, wind, sunlight, etc.) with the purpose? to protect or a portion of space or an environment and what? that the? ? content.

Additionally, the nets can be used as a mulch against worms or weeds, or they can be used to protect animals in pens and stables from flies and other insects. In order to better illustrate the embodiments of the invention, some examples are given below which are not to be considered limiting.

Methods for the determination of products impregnated in networks.

The following chromatographic methods are used to determine the quantities of the impregnated products depending on the substance to be determined.

a) GC-MS method

The dried net sample is extracted twice with 20 ml of CH2Cl2 and the collected fractions were analyzed with a gas chromatograph equipped with a mass detector, using a column and a method suitable according to the substance to be examined. In general, the analytical method ? was developed following a temperature gradient over time using He as a carrier gas.

b) HPLC method

The dried net sample is extracted with 10 mL of 100% ethanol. The solution is filtered in a suitable 0.45 µm filter and injected into HPLC with the appropriate dilution. A C18 stationary phase and an Acetonitrile/Water mixture as an elution step ? generally preferred following a gradient where the percentage of acetonitrile increases over time.

Discussion of some embodiments of the invention

Example 1

Impregnation with geraniol of a network containing 7% by weight of surface hydrogel (hydrogel weight/support weight) formed by polyvinylpyrrolidone and EGDMA.

100 grams of polyethylene mesh containing 7% by weight of surface hydrogel were immersed at 25 ? C in 500 ml of an ethanolic solution containing 3.4 g of geraniol.

The mixture ? been agitated at 25 ? C for 18 hours at 40 rpm. The polyethylene net? it was then removed from the ethanol and dried at 20 ?C under forced air circulation for 4 hours and used for the further tests. The quantity? of absorbed geraniol ? was determined by HPLC.

quantity theory of geraniol absorbed 48.5% of the hydrogel.

Found: 2% of the hydrogel.

Example 2

Impregnation with lavender oil of a network containing 5% by weight of surface hydrogel (hydrogel weight/support weight) formed by polyvinylpyrrolidone and EGDMA.

100 grams of polyethylene mesh containing 5% by weight of surface hydrogel were immersed at 25 ? C in 400 ml of ethanolic solution containing 3.2 g of lavender oil. The mixture ? was stirred at 25 ?C for 18 hours at 50 rpm. The polyethylene net? it was then removed from the ethanolic solution and dried at 20 ?C under forced circulation of air for 4 hours and used for the further tests. The quantity? of lavender oil absorbed ? was determined by GC-MS for the linalool component.

quantity theory of lavender oil absorbed: 64% of the current hydrogel.

Found 55% of the current hydrogel.

Example 3

Impregnation with pyrethrum extract of a network containing 5% by weight of surface hydrogel (hydrogel weight / support weight) formed by polyvinylpyrrolidone and EGDMA.

100 grams of polyethylene mesh containing 5% by weight of surface hydrogel were immersed at 25 ?C in 500 ml of 95% ethanol where previously 9.2 g of pyrethrum extract (50% w/w in ether of oil). The mixture ? been stirred at 25 ?C for 18 hours at 50 rpm, then the net ? was removed from the ethanolic solution and dried at 30 ?C under forced air circulation for 12 hours and used for the further tests. The quantity? of absorbed pyrethrum extract ? was determined by HPLC.

quantity theory of pyrethrum extract absorbed: 92% of the hydrogel present.

Found: 85% by weight of the quantity? of hydrogel.

Example 4

Impregnation with azadirachtin of a network containing 5% by weight of surface hydrogel (hydrogel weight/support weight) formed by polyvinylpyrrolidone and EGDMA.

100 grams of polyethylene net containing 5% by weight of surface hydrogel were immersed at 25°C in 500 ml of 95% ethanol where previously 2.0 g of azadirachtin were dissolved. The mixture ? been stirred at 25 ?C for 18 hours at 50 rpm, then the net ? dried at 30 ?C under forced air circulation for 12 hours and used for further tests. The quantity? of absorbed azadirachtin? was determined by HPLC.

quantity theoretical amount of absorbed azadirachtin: 40% of the current hydrogel.

Found: 4% by weight of the amount? of hydrogel.

Brief discussion on properties of absorption

As can be seen from the examples shown, although all the active substances tested are absorbable from the hydrogel present on the support, the capacity? absorption varies significantly.

In particular yes? seen that lavender oil and pyrethrum have the maximum absorption efficiency, expressed as the ratio between the quantity? of active ingredient actually absorbed and the quantity? of active ingredient theoretically absorbable by the hydrogel as it is present in the solution used.

Efficacy test

It is specified that by sensitive population we mean a population of insects not previously exposed to synthetic insecticides. By resistant population we mean a population of insects which, having been exposed to synthetic insecticides, has developed resistance to them.

To determine the effectiveness of the nets as previously impregnated, the completely sensitive population of aphids Myzus persicae (S) (Mp-1X) and the resistant one (R) (Mp92H6) were used. p

The tests were carried out by inserting ?falcon? from 50 ml the net and then inserting about 60 aphids. After 3 hours the aphids were transferred to untreated pea plants. Mortality? ? was evaluated at that time and after another 24 hours.

For population S, the test ? been replicated 3 times using about 60 aphids for each type of net. For the population R, the test ? been replicated 4 times using the same methodology. Statistical analysis? been carried out on the mortality data? via ANOVA method after verifying the conditions of homogeneity? of the variances with the Levene test. Means were separated by Tukey's test (significance level p = 0.05).

The control test was represented by a polyethylene support in the form of a mesh or fabric, covalently bonded with a hydrogel-forming polymer without any active ingredient absorbed. The calculated efficacy values are reported as a percentage of the mortality? observed and reported in Table 1 (sensitive population) and in Table 2 (resistant population) Table 1 - Efficacy values obtained by treating the sensitive population.

Table 2 - Efficacy values obtained by treating the resistant population.

Efficacy test after washing

A further test using the population S ? was carried out using the mesh of Example 3 after having washed the mesh, in order to evaluate the resistance to washing of the support made according to the invention.

A fragment of a 5x5 cm net made as in example 3 ? was placed in a 50 mL "falcon" tube and 10 mL of water was added. After shaking for 10 seconds at 2000 rpm, ? water was collected.

The biotest? been performed by inserting the net inside a ?falcon? from 50 ml and then inserting about 60 aphids. After 3 hours the aphids were transferred to untreated pea plants. Mortality? ? was evaluated at that time and after another 24 hours. The test ? been replicated a total of 3 times using about 60 aphids for each network of Example 3. The statistical analysis ? been conducted on the mortality data? as previously reported. The calculated efficacy values are shown in Table 3 as a percentage of the mortality? observed in Table 3.

Table 3 - Efficacy values obtained by treating the sensitive population after washing

Claims (15)

Claims 1. Polyethylene support in the form of a net or fabric for use as a pesticide, on the surface of which a hydrogel is bonded comprising polyvinylpyrrolidone and ethylene glycol dimethyl acrylate, said hydrogel being filled with at least one active ingredient selected from natural insecticides, natural fungicides, natural herbicides , natural repellents or their active components from plant extracts. 2. Support according to claim 1 characterized in that said at least one natural active principle? chosen from the list including: Tanacetum cinerariaefolium pyrethrum extract, bergamot oil, cinnamon oil, clove oil, lemongrass oil, cypress oil, eucalyptus oil, fennel oil, garlic oil, grapefruit oil , thyme oil, geranium oil, lavender oil, neem oil, orange oil, rosemary oil, manuka oil, peppermint oil, Alaskan yellow cedar oil, Clitoria ternatea oil, thyme oil , white cypress oil, allicin, azadirachtin, eucalyptus, thymol, ?-pinene, ??pinene, p-cymene, d-limonene, 1,8-cineole, citral, eugenol, geraniol, leptospermone, linalool, phellandrene, pyrethrins, tea tree oil, lemongrass oil, lemon eucalyptus oil, ginger oil 3. Support according to claim 2 characterized in that said at least one natural active principle? chosen as a natural insecticide from the list including: pyrethrum extracts, thyme oil, clove oil, neem oil, thymol, azadirachtin, allicin, cineole 1,8, eugenol and d-limonene 4. Support according to claim 2 characterized in that said at least one natural active principle? chosen as a natural herbicide from the list including: clove oil and pelargonic acid 5. Support according to claim 2 characterized in that said at least one natural active principle? chosen as a natural fungicide from the list including: geranium oil, geraniol, eugenol, thymol 6. Support according to claim 2 characterized in that said at least one natural active principle? chosen as a natural repellent from the list including: thyme oil, geranium oil, citronella oil, mint oil, geraniol, eugenol, thymol and eucalyptol. 7. Support according to claim 3 characterized in that said at least one natural active principle comprises the pyrethrum extract, to which a photostabilizing product selected in the class of UV protection agents such as benzophenones and benzotriazoles has been added. 8. Support according to one of the preceding claims characterized in that said at least one natural active principle? microencapsulated in organic polymers. 9. Support according to one of the preceding claims characterized in that said hydrogel is bonded to the surface of said support by a method comprising the steps of: - Immersion of the support in a toluene solution containing ethylene glycol dimethyl acrylate (EGDMA) and cumene hydroperoxide; - immersion of the support in an aqueous solution containing: FeCl2*4H2O, ascorbic acid and polyvinylpyrrolidone - washing of the support using an alcoholic solvent - drying of the substrate. 10. Support according to claim 9 characterized in that said alcoholic solvent is ethanol or its mixtures with water. 11. Support according to one of the preceding claims characterized in that the weight ratio between the surface hydrogel and the support ? between 1 and 15%. 12. Support according to one of the preceding claims characterized in that the weight ratio between the surface hydrogel and the support ? between 5 and 10%. 13. Process for impregnating the hydrogel bound to a support according to one of the preceding claims with at least one natural active ingredient, comprising the steps of: to. immerse the polyethylene support containing the covalently bonded hydrogel in a solvent in which at least one natural active ingredient is dissolved in an amount between 20% and 99% by weight with respect to the quantity? of hydrogel present on the support; b. mix the mixture in which ? immersed the support for a period of time between 8 and 24 hours; c. remove the substrate from the mixture and dry it. 14. Use of the antiparasitic fabric according to one of the preceding claims as an insecticide, fungicide and repellent 15. Use of the antiparasitic fabric according to one of claims 1 to 9 for protecting crops, animals and humans from insects and fungi