Use of plastic products containing PBSA and an insect repellent for pest control

Abstract

Use of Plastic Products Comprising PBSA and an Insect Repellent for Pest Repulsion. The present invention relates to the use of plastic products comprising PBSA and an insect repellent for pest repulsion. The insect repellent is selected from essential oils, the aerial parts of sweet potato plants, and mixtures thereof. The invention also relates to such a plastic product, as well as a method for manufacturing such a plastic product, preferably by extrusion.

Description

Title of the invention: Use of plastic products comprising PBSA and an insect repellent for pest control. Technical field of the invention

[0001] The present invention relates to the use of polybutylene succinate adipate (PBSA) plastic products to repel pests such as aphids, particularly in agricultural applications. Technological background

[0002] Every year, crops are subjected to dangerous insect pests, resulting in considerable economic losses (estimated at €250 billion worldwide) and potentially dangerous risks to soil, groundwater, and human health due to the use of chemical pesticides. For example, aphids are among the most damaging taxa for all cultivated plants. In fact, their control is difficult because they exhibit specific feeding behavior and unusual reproductive biology. Current protection strategies based on the intensive use of chemicals are considered unsustainable for the development of sustainable agriculture due to their negative impact on the environment and human health. Moreover, this approach has led to the development of insect resistance to pesticide treatments.For these reasons, the French government published the "Ecophyto II" program in October 2015 to achieve the goal of halving the use of plant protection products by 2025 by encouraging new solutions for sustainable agriculture based on innovative biological molecules. In recent years, another alternative for reducing the development of insect resistance to the use of chemicals and pesticides has emerged through the development of physical barriers such as insect netting, which is primarily made of polyethylene. However, this is a palliative approach involving the management of these materials at the end of their life cycle, as they are neither biodegradable nor compostable. Such polymeric materials require separation processes from plant debris (components, soil, rocks, water, adsorbed biofilm, etc.).) through intensive washing processes that consume a significant amount of water before being reprocessed.

[0003] Currently, European countries are encouraging industry to reconsider its production methods in order to reduce the use of fossil resources and minimize the environmental impact of products throughout their life cycle. For these various reasons, new French and European regulations as well Environmental challenges such as plastic pollution represent a real opportunity for the development of new bio-based and / or compostable materials. Consequently, bio-based materials are primarily based on components derived from crops, i.e., annually renewable resources such as sugarcane, corn, oils, etc. However, these bio-based materials do not possess sufficient intrinsic properties to be easily processed using conventional melt-processing methods such as extrusion or melt spinning, particularly for applications requiring combined performance characteristics such as mechanical properties (stress and strain at equilibrium fracture). Water barrier properties and additional functionalities such as insect resistance must also be considered.

[0004] PBSA, or poly(butyl succinate), more commonly known by its English name polybutylene succinate adipate, is an aliphatic polyester obtained by copolymerization of monomers of 1,4-butanediol, succinic acid, and adipic acid. It is a polymer of choice for use in agriculture because it is a biopolyester, now 35% bio-based. In particular, the succinic acid used for the synthesis of PBSA can be bio-based. Furthermore, PBSA is biodegradable under various conditions such as industrial composting, home composting, and soil composting. Biodegradability is defined in particular in NF EN 13432:2000. Finally, the high flexibility of PBSA allows it to be used for the manufacture of films.

[0005] In order to impart particular properties to polymeric products such as PBSA plastic products, it may be desirable to incorporate into the plastic product additives such as colorants, fillers, plasticizers, compatibilizers, agents modifying mechanical properties or pest control agents such as insecticides and / or insect repellents.

[0006] WO2009 / 095624 describes the use of 3,5-dicafeoylquinic acid and its derivatives For the repulsion or elimination of aphids of various species. These compounds are extracted from the non-tuberous roots of the sweet potato plant.

[0007] Essential oils are also known to have repellent activity against pests, such as aphids. For example, JPH09110623 describes the use of a mixture of specific essential oils to repel aphids.

[0008] These naturally derived active ingredients are known to have interesting insect-repellent properties against aphids. It would therefore be advantageous to incorporate these insect-repellent active ingredients into PBSA plastic products such as PBSA films. The resulting products would offer the dual advantage of being insect-repellent against insects such as aphids and being biodegradable. Furthermore, naturally derived active ingredients such as Essential oils and the aerial parts of the sweet potato plant are intended to replace traditional chemical pesticides.

[0009] PBSA plastic products, in particular PBSA films, are conventionally manufactured by extrusion, which requires working in a molten state, involving heating to temperatures above 100°C. Certain additives such as insect-repellent agents may be at least partially degraded at such temperatures.

[0010] To the inventors' knowledge, no process has been described that would allow the incorporation of naturally derived insect-repellent active ingredients, selected from essential oils and the aerial parts of sweet potato plants, into PBSA plastic products such as PBSA films, without degrading said active ingredients and thus without affecting their insect-repellent properties. It would therefore be advantageous to have manufacturing processes for PBSA plastic products such as PBSA films that allow the incorporation of such insect-repellent active ingredients into the plastic product without degrading them. Advantageously, these processes would involve melt-state processes, in particular extrusion, which are the processes of choice for shaping PBSA plastic products.

[0011] In this context, the inventors have demonstrated that it is possible to obtain high levels of pest repellency with plastic products comprising a PBSA matrix in which an insect-repellent active ingredient selected from essential oils and the aerial parts of sweet potato plants is integrated. They have further demonstrated that the insect-repellent activity of the active ingredient is not, or only slightly, affected by the extrusion process used to manufacture the plastic product. Summary of the invention

[0012] Thus, a first object of the present invention is the use of a plastic product comprising polybutylene succinate adipate (PBSA) and an insect-repellent active ingredient chosen from essential oils, aerial parts of sweet potato plants and mixtures thereof, for the repulsion of pests such as insects.

[0013] In some embodiments, the plastic product is chosen from the group consisting of insect nets, tarpaulins for agricultural fields, plastic tarpaulins, storage bags and gardening pots.

[0014] In some embodiments, the pests are insects of the Aphidoidea family such as aphids.

[0015] In some embodiments, the essential oil is chosen from the group consisting of basil essential oil, mint essential oil, peppermint essential oil, cinnamon essential oil such as oil Chinese cinnamon essential oil, marigold essential oil, rosemary essential oil and one of their mixtures.

[0016] In some embodiments, the plastic product has a thickness of less than 100 micrometers.

[0017] In some embodiments, the aerial parts of sweet potato are a shredded sweet potato plant leaf mash.

[0018] In some embodiments, the plastic product comprises at least one other polymer in addition to PBSA, preferably PHB, PHBV or a mixture thereof.

[0019] In some embodiments, the quantity of insect repellent active is 0.5 to 5% by weight relative to the total weight of the PBSA+insect repellent active mixture.

[0020] In some embodiments, the plastic product is manufactured by a melt-state technique such as extrusion, in particular conventional extrusion or blow molding.

[0021] Another object of the invention is a plastic product, in particular a plastic film, comprising PBSA and an insect-repellent active ingredient selected from essential oils, aerial parts of sweet potato plants and mixtures thereof.

[0022] Another object of the invention is a method for manufacturing a plastic product comprising polybutylene succinate adipate (PBSA) and an insect-repellent active ingredient selected from essential oils, aerial parts of sweet potato plants and mixtures thereof, comprising a melt extrusion step of a mixture comprising polybutylene succinate adipate (PBSA) and the insect-repellent active ingredient. Brief description of the drawings

[0023] Fig. 1 is a photograph of the device used for repulsive choice tests.

[0024] Fig. 2 is a comparative thermogram of sweet potato leaves on the one hand, and DiCQ on the other.

[0025] The [Fig.3] is the thermogram of the film comprising 10% by weight of sweet potato leaves.

[0026] The [Fig.4] is the thermogram of the film comprising an amount of pure DiCQ equivalent to that contained in 10% by weight of sweet potato leaves.

[0027] Figure 5 includes thermograms of the essential oils alone, of PBSA alone, and of mixtures of PBSA + essential oils at 1% (left) and 5% by weight (left). The essential oils are designated as follows: BAS = basil; SPE = mint; PEP = peppermint; and CIN = Chinese cinnamon.

[0028] Figure 6 is a histogram showing the proportion of aphids on the control side (i.e., experiencing the repellent effect) for PBSA films containing 1%, 2%, 3%, 4%, or 5% of each essential oil. The essential oils are designated as follows: BAS = basil; SPE = mint; PEP = peppermint and CIN = Chinese cinnamon. Detailed description

[0029] Use of the plastic product

[0030] A first object of the invention is the use of a plastic product comprising polybutylene succinate adipate (PBSA) and an insect-repellent active ingredient selected from essential oils, aerial parts of sweet potato plants and mixtures thereof, for the repulsion of pests such as insects.

[0031] The term "insect repellent active ingredient" refers to a compound or mixture of compounds that has a repellent effect on at least one type of insect when used in an appropriate quantity. Insecticides are also considered examples of insect repellent active ingredients according to the invention.

[0032] The term "pests" refers to animals whose activities, in whole or in part, have detrimental effects on the proper conduct of certain human activities (agriculture, fish farming, game management, forestry, etc.). Preferably, pests are insects.

[0033] The insects can be any type of insect. They include, in particular, aphids (family Aphidoidea), whiteflies, scale insects, flies, and mosquitoes. In some embodiments, they are aphids.

[0034] The use of the plastic product is preferably in the agricultural field.

[0035] Plastic product

[0036] The term "plastic product" refers to a product comprising at least one polymer, such as a plastic sheet, tube, rod, profile, shape, solid block, fiber, etc. Preferably, the plastic product is a manufactured product, such as rigid or flexible packaging (trays, cups, etc.), agricultural films, bags, disposable or similar items, etc. The plastic product may contain additional substances or additives, such as plasticizers, minerals, organic fillers, compatibilizers, or colorants. The term "plastic product" also encompasses granules, extruded rods, fibers, films, powders, etc., which may be further shaped to obtain the manufactured products.

[0037] Examples of plastic products according to the present invention include, but are not limited to, pipes, tapes, irrigation fittings, plastic films for greenhouse and tunnel covers, water storage tanks, mulch films, insect nets, agricultural field tarpaulins, plastic tarpaulins, storage bags and pots for gardening, preferably insect nets or mulch films.

[0038] A "polymer" refers to a chemical compound or a mixture of compounds whose structure consists of several repeating units called monomers, which are linked by covalent chemical bonds. In the context of the invention, the term "polymer" designates such a chemical compound or mixture of compounds forming part of the composition of a plastic product.

[0039] The plastic products used according to the invention comprise PBSA. The PBSA used may be of any molar mass and density suitable for shaping into a plastic product. Preferably, the molar mass of the PBSA is between 20,000 g / mol and 80,000 g / mol, in particular between 40,000 g / mol and 60,000 g / mol. Preferably, the density of the PBSA is between 1200 and 1300 kg / m³, preferably between 1230 and 1260 kg / m³. The PBSA may have any molar ratio of succinate units to adipate units. Preferably, the molar ratio of succinate units to adipate units is between 0.9:0.1 and 0.5:0.5, in particular it may be about 0.75:0.25. The PBSA used may be food grade or non-food grade. It may include bio-based PBSA, such as BioPBS® brand PBSA marketed by Mitsubishi Chemical or Bionolle® brand PBSA marketed by Resonac.

[0040] The thermal and mechanical properties of the plastic product, in particular the film, of PBSA are preferably not affected by the incorporation of the insect-repellent active ingredient into the plastic product.

[0041] The plastic product used according to the invention can be considered as comprising a polymer matrix including PBSA and an insect-repellent active ingredient. The insect-repellent active ingredient is preferably distributed homogeneously within the polymer matrix including the PBSA.

[0042] In some embodiments, the plastic product comprises PBSA as the sole polymer. Preferably, the plastic product comprises a polymer matrix consisting of PBSA and the insect-repellent active ingredient.

[0043] In some embodiments, the plastic product comprises at least one other polymer in addition to PBSA. This at least one other polymer may, in particular, be a polyolefin such as polyethylene or polypropylene, starch, a polyester such as polybutylene adipate terephthalate (PBAT), poly[3-hydroxybutyrate] (PHB), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), or polylactic acid (PLA). In one embodiment, the at least one other polymer is selected from the group consisting of PHB, PHBV, and mixtures thereof. Preferably, when the plastic product comprises at least one other polymer in addition to PBSA, said at least one other polymer is biodegradable and / or compostable. When the plastic product comprises at least one other polymer in addition to PBSA, the ratio of PBSA to the other polymer This can vary considerably. Preferably, the ratio of PBSA to the other polymer in the plastic product is between 5:95 and 95:5 by mass relative to the total mass (PBSA + other polymer). Preferably, PBSA represents at least 50% by mass relative to the total mass (PBSA + other polymer).

[0044] In some embodiments, the PBSA and at least one other polymer are mixed in the plastic product, in which case the insect-repellent active ingredient is incorporated into the PBSA / other polymer mixture.

[0045] In other embodiments, the PBSA and at least one other polymer represent two distinct parts of the plastic product. For example, if the plastic product is a multilayer film, the PBSA and at least one other polymer may each represent a layer of the film. In such a case, the insect-repellent active ingredient is preferably incorporated only in the PBSA.

[0046] In some embodiments, the plastic product comprises several layers (multilayer product), and the PBSA and the insect-repellent active ingredient are included in the same layer.

[0047] The plastic product can be manufactured by any suitable technique known in the art. In some preferred embodiments, the plastic product is manufactured by a melt-state technique, in particular conventional extrusion, blow molding or blow molding, especially conventional extrusion or blow molding.

[0048] The amount of insect repellent active ingredient in the plastic product can vary to a wide extent. Preferably, the insect repellent active ingredient is in a proportion of between 0.5% and 10%, preferably between 0.5% and 5%, in particular between 1 and 5% by weight, relative to the total weight of the polymer matrix, in particular the PBSA matrix, and the insect repellent active ingredient.

[0049] Thus, an object of the invention is a plastic product, in particular a plastic film, comprising PBSA and an insect-repellent active ingredient selected from essential oils, the aerial parts of sweet potato plants, and mixtures thereof. Preferably, the insect-repellent active ingredient is contained within a plastic matrix consisting essentially of, in particular of, PBSA.

[0050] In certain embodiments, particularly when it is a film, the plastic product has an average thickness of less than 100 microns, in particular an average thickness of less than 80 microns, in particular an average thickness of less than 50 microns.

[0051] Essential oil

[0052] In some embodiments, the insect-repellent active ingredient present in the plastic product includes at least one insect-repellent essential oil.

[0053] In some embodiments, the insect-repellent essential oil is selected from the group consisting of basil essential oil, mint essential oil, peppermint essential oil, cinnamon essential oil such as Chinese cinnamon essential oil, marigold essential oil, rosemary essential oil, and mixtures thereof. In preferred embodiments, the essential oil is selected from the group consisting of basil essential oil, mint essential oil, peppermint essential oil, cinnamon essential oil such as Chinese cinnamon essential oil, and mixtures thereof. In some embodiments, the essential oil is basil essential oil. In some embodiments, the essential oil is peppermint essential oil. In some embodiments, the essential oil is mint essential oil. peppermint. In some embodiments, the essential oil is cinnamon essential oil such as Chinese cinnamon essential oil.

[0054] The quantity of essential oil in the plastic product can vary to a wide extent. Preferably, the essential oil or mixture of essential oils is contained in a proportion of between 0.5% and 10%, in particular between 1% and 5% by weight, relative to the total weight of the polymer matrix, in particular the PBSA matrix, and the insect-repellent active ingredient.

[0055] Aerial parts of sweet potato plant

[0056] In some embodiments, the insect-repellent active ingredient present in the plastic product comprises all or part of the aerial parts of the sweet potato plant. In some embodiments, the aerial parts of the sweet potato plant are sweet potato plant leaves and / or sweet potato plant stems, preferably sweet potato plant leaves.

[0057] The sweet potato, or potato, is a species of dicotyledonous plants of the family Convolvulaceae, tribe Ipomoeeae, species Ipomea batatas.

[0058] The aerial parts of sweet potato can be incorporated into the plastic product in any suitable form. In particular, they can be introduced whole or their size can be reduced, especially to facilitate dispersion and / or mixing in the polymer matrix.

[0059] In some embodiments, the aerial parts of sweet potato are incorporated into the polymer matrix in the form of a powder. The particle size of the powder can vary considerably. Preferably, the particle size is adapted to the requirements of the subsequent shaping of the plastic product. Thus, when the plastic product is thin, such as a film or a tarpaulin, it is preferable for the particle size to be less than the desired thickness of the plastic product.

[0060] In certain embodiments, the aerial parts of sweet potato are in the form of a ground powder with a particle size of less than 70 micrometers, preferably less than 50 micrometers, and in particular less than 30 micrometers. Preferably, the particle size is not less than 0.5 micrometers, and preferably not less than 1 micrometer. "Particle size" refers to the average particle size of the ground aerial parts of sweet potato.

[0061] The quantity of aerial parts of sweet potato plant in the plastic product can vary to a wide extent. Preferably, the aerial parts of sweet potato plant are comprised in a proportion of between 0.5% and 10%, in particular between 1 and 5% by weight, relative to the total weight of the polymer matrix, in particular the PBSA matrix, and the insect-repellent active ingredient.

[0062] The aerial parts of sweet potato preferably contain DiCQ (3,5-dicafeoylquinic acid).

[0063] In some embodiments, the insect-repellent active ingredient is a mixture of at least one essential oil and aerial parts of sweet potato. The mass ratio of the at least one essential oil to the aerial parts of the sweet potato plant can vary considerably. It can, for example, range from 5:95 to 95:5, particularly from 30:70 to 70:30, and is in particular approximately 50:50 by mass.

[0064] In some embodiments, the insect repellent active is a mixture of at least one essential oil and aerial parts of sweet potato, the at least one essential oil is included in a quantity in a proportion of between 0.5% and 10%, in particular between 1 and 5% by weight, relative to the total weight of the polymeric matrix, in particular the PBSA matrix, and the insect repellent active, and the aerial parts of sweet potato plant are included in a proportion of between 0.5% and 10%, in particular between 1 and 5% by weight, relative to the total weight of the polymeric matrix (in particular the PBSA matrix) and the insect repellent active.

[0065] In some embodiments, the insect-repellent active ingredient is a mixture of at least one essential oil and aerial parts of sweet potato, and the mixture of at least one essential oil and aerial parts of sweet potato is comprised in an amount in a proportion of between 0.5% and 10%, in particular between 1% and 5% by weight, relative to the total weight of the polymeric matrix, in particular the PBSA matrix, and the insect-repellent active ingredient.

[0066] Without wishing to be bound by any theory, the Inventors consider that the presence of at least one essential oil makes it possible to improve the compatibility of the aerial parts of the sweet potato plant with the polymeric matrix comprising PBSA, and thus facilitate their incorporation into the matrix, in particular by extrusion.

[0067] Method for manufacturing the plastic product

[0068] Another object of the present invention is a method for manufacturing a plastic product comprising PBSA and an insect-repellent active ingredient selected from essential oils, aerial parts of sweet potato plants and mixtures thereof, comprising a melt extrusion step of a mixture comprising PBSA and the insect-repellent active ingredient.

[0069] The terms "in the molten state" refer to conditions in which the polymeric matrix comprising the PBSA is at least partially molten.

[0070] In some embodiments, the extrusion is a conventional extrusion. In other embodiments, the extrusion is an extrusion-blowing.

[0071] The extrusion is carried out under conditions, in particular temperature and time conditions, adapted for mixing the insect repellent active ingredient and the polymeric matrix, preferably the PBSA polymeric matrix.

[0072] Preferably, the extrusion is carried out at a temperature at which the polymer matrix is ​​partially or totally melted, preferably totally melted. Using a temperature at which the polymer matrix is ​​totally melted promotes the homogeneous distribution of the insect-repellent active ingredient within the polymer matrix.

[0073] Extrusion is preferably carried out at a temperature greater than or equal to 110°C, preferably at a temperature between 130°C and 160°C.

[0074] Extrusion is preferably carried out at a temperature limiting the degradation of the insect-repellent active ingredient.

[0075] In some embodiments, the polymer matrix is ​​mixed with the insect-repellent active ingredient before extrusion. In other embodiments, the insect-repellent active ingredient is added to the polymer matrix during extrusion. Adding it during extrusion helps to minimize the thermal stress to which the insect-repellent active ingredient is subjected.

[0076] In some embodiments, the manufacturing process includes a subsequent step of shaping the plastic product, which can in particular be carried out by injection or extrusion.

[0077] The term "approximately" placed before a numerical value designates an interval between plus and minus ten percent of the numerical value, preferably between plus and minus five percent of the numerical value, in particular between plus and minus one percent of the numerical value.

[0078] In the present invention, the term "include" and its variations are generally non-limiting, meaning that the product may include other elements in addition to those indicated. In certain embodiments, the term "include" may be interpreted more narrowly and mean "to be essentially made up of," or even "to be made up of."

[0079] The invention will be better understood in light of the examples below, which are to be considered illustrative and not limiting of the scope of the invention. Examples

[0080] Example 1: Insect-repellent effect of a PBSA film comprising crushed sweet potato plant leaves

[0081] Film preparation

[0082] The PBSA films were prepared as follows. PBSA granules were dried at 60°C overnight. The films were prepared using a 15g capacity extruder, model DSM micro-extruder (Midi 2000 Heerlen NL), with co-rotating screws (length-to-diameter ratio L / D of 18). The mixtures were processed at 160°C for 3 minutes at a rotation speed of 100 rpm. A 200-micron flat die was used.

[0083] Experimental site

[0084] The repellent tests were carried out in a climate chamber with a temperature setpoint of 20°C (± 2) and a relative humidity (RH) of 65% (± 5). The lighting, consisting of PHILIPS cool white LED tubes and OSRAM Fluora fluorescent tubes, had a photoperiod of 16h:8h (D:N).

[0085] Aphids

[0086] Aphids are a major crop pest. The pea aphid, Acyrthosiphon pisum, is a species found in vegetable gardens on many cultivated Fabaceae and is a widely studied model organism in research due to its life cycle, which is characteristic of most aphids, and its optimal size for experimentation. The A. pisum aphids placed in the apparatus on day 0 of the tests are wingless NI nymphs, all hatched from a rearing of winged adult aphids on broad beans, all synchronized in a climate chamber.

[0087] Treatment

[0088] Aphids were exposed for 24 hours to potentially repellent biopolymer films, first by olfaction and then by contact. To this end, samples of the films were placed near an artificial medium, AP3, designed for pea aphid nutrition and reproducing the amino acid composition of the aphid. Aphids placed at a distance from the medium and film complex had to choose between the repellent film and the control film by olfaction, then either bypass or come into contact with the films to reach and feed on the nutrient medium.

[0089] Experimental device

[0090] The selection tests were carried out on strips perforated with 6 chambers. Two tubes are sealed on either side of these chambers, with AP3 material coupled to a 30x5mm strip of control film on one side and repellent film on the other. The [Fig. 1] shows a photograph of the apparatus used. Six aphids were placed in each chamber, and then the strip was placed in a dark box to avoid bias from light. Three replicates per film were performed, corresponding to three strips.

[0091] Statistical measurements and tests

[0092] The number of aphids attached to the media or within 1 cm was counted on each side of the strips. The difference between the proportion of aphids attached to the control film and the proportion attached to the repellent film was statistically analyzed using a 2:2 chi-square test with a significance level of 5% (0.05). The statistical analysis was first performed between replicates of each trial to ensure their homogeneity, and then between all the repellent films. Finally, a repulsion index (RI) was calculated to assign a final repulsiveness level to each film tested. Positive and negative values ​​indicate a repellent and attractive effect, respectively.

[0093] Ir = [(Nb witness - Nb repellent) / Nb Total] xlOO, where: Repellent number = number of aphids attached to the medium coupled with the repellent film. Control number = number of aphids attached to the medium coupled with the control film. Total number = total number of aphids attached.

[0094] Film Repulsion Indices

[0095] Repulsion indices were calculated for films containing different amounts of sweet potato leaf powder (1% by weight and 3% by weight). They were also calculated for a comparative PBSA film containing no sweet potato leaf powder (0% by weight) and for a PBSA film containing pure DiCQ (3,5-dicafeoylquinic acid) in an amount equivalent to 10% by weight of sweet potato leaf powder, at a concentration of 5.9 mg / g of sweet potato leaves. The thickness of the film containing DiCQ is 230 micrometers ± 10 micrometers.

[0096] Table 1 below details the results obtained and the film repulsion indices. The statistical index is determined by a Chi-square statistical test (P>0.05), and letters are assigned according to significant differences.

[0097] [Tables 1] Sweet potato film 0 wt% 1 wt% 3 wt% DiQQ Total number of aphids 36 36 36 36 36 36 36 36 36 91 Of which number of aphids on control 18 17 19 25 24 27 28 27 56 Number of aphids on repellent 18 19 17 11 12 11 9 8 9 35 0 0 -5.5 +5.5 38.8 33.3 38.8 50.0 55.5 50.0 23.1 Average 0 0 +7- 5 5 37.0 + / - 3..2 51.7 + / - 2.9 Statistical index abc

[0098] The repellency indices of the films containing 1% and 3% by mass of ground sweet potato plant leaves are 37% and 52% respectively, demonstrating a very good repellent effect of the films. In comparison, the repellency index of the film containing DiCQ alone is only 23%.

[0099] Example 2: Comparison of the thermal properties of DiCQ and sweet potato leaves before and after inclusion in films

[0100] Figure 2 shows the comparative thermogravimetric analysis curves of DiCQ and sweet potato leaf powder. This analysis demonstrates that DiCQ degrades at a lower temperature than sweet potato leaves. Thus, at a temperature of 130 °C, the mass loss of DiCQ is 5.5% compared to 2.7% for sweet potato leaves. Then, at 180 °C, the loss is 8.2% for DiCQ compared to 4.5% for sweet potato leaves.

[0101] Figures 3 and 4 show the comparative thermogravimetric analysis curves of PBSA films containing 10% by weight of sweet potato leaves and an amount of pure DiCQ equivalent to 10% by weight of sweet potato leaves, respectively. Although the two thermograms are similar, a slight advanced degradation can be observed for the film containing sweet potato leaves, which is not observed for the film containing pure DiCQ. This suggests that the film intended to contain pure DiCQ contains little or no active DiCQ, since otherwise degradation should be observed at temperatures close to that observed for the film containing sweet potato leaves. This therefore suggests that the pure DiCQ introduced into the PBSA film was partially degraded during extrusion to a greater extent than when it was introduced via the sweet potato leaves. The extrusion temperature was 160°C.

[0102] Example 3: Thermal and mechanical properties of a film according to the invention

[0103] The thermal and mechanical properties of a PBSA film containing different amounts (5% and 10% by weight) of sweet potato plant leaves were measured and compared to those of a PBSA film. The results are presented in Tables 2 and 3 below.

[0104] [Tables2] Sample PBSA PBSA + 5% by weight PBSA + 10% by weight Young's Modulus 310 MPa 250 MPa 240 MPa Strain 450% 450% 340% Tensile Strength 17 20 15

[0105] Despite the observation of a slight decrease in Young's modulus and strain at break (for a rate of 10%), it can be considered that the incorporation of up to 10% of sweet potato plant leaves does not significantly affect the mechanical properties of the PBSA film.

[0106] [Tables3] PBSA Sample PBSA + 5% wt PBSA + 10% wt Tg (°C) -47 -44 -44 Melting point (°C) 88.2 86 87 % crystallinity 27 32 28

[0107] The incorporation of 5 to 10% by weight of sweet potato leaves does not influence the thermal properties of the PBSA film, whether in terms of glass transition temperature, melting temperature or degree of crystallinity.

[0108] Example 4: Manufacture of PBSA films containing essential oils

[0109] Materials and methods

[0110] PBSA FD92PB BioPBS® was purchased in granular form from Mitsubishi Chemical Europe GnbH. The ratio of butylene succinate to butylene adipate units in commercial grade PBSA such as that used in this study is approximately (PBS₂₅-CPBA₂₅-

[0111] The essential oils were supplied by VosHuiles (Nevers, France) and are from conventional or organic industrial harvests around the world.

[0112] Preparation of PBSA / essential oil mixtures

[0113] PBSA granules loaded with each essential oil at 1, 2, 3, 4 and 5% by weight were prepared by direct incorporation into the molten polymer matrix using a co-rotating twin-screw extruder with 18 heating zones (L / D=68, D=18 mm, ZSE 18 HPe models, Leistritz Extrusionstechnik GmbH, Nuremberg, Germany). The extrusion parameters were determined through preliminary tests to provide the best compromise between a homogeneous molten mixture and minimal thermal stress for the essential oils, particularly with a starting temperature of 120°C ± 10°C. The screw speed was set at 300 rpm, and the temperature within the extruder ranged from 35°C to 130°C. Zone 1 was maintained at 35°C. Zones 2 through 7 were maintained at 130°C. Zones 8 and 9 were maintained at 120°C. Zones 10 through 18 were maintained at 115°C. PBSA was introduced in zone 1, and the essential oil in zone 10.

[0114] The PBSA was oven-dried at 60°C overnight and then introduced into zone 1 at a feed rate of 2 kg / h using a DSR28-20 doser (Kubota Brabender Technologie GmbH, Duisburg, Germany) equipped with a single screw pump (reference 2019) and a tube (reference 260). The essential oils were injected into zone 10 using a Gilson 305 piston pump (Middleton, WI, USA) equipped with a 25SC head. The essential oils were introduced into a remote zone to limit their residence time (estimated at 1 to 2 minutes).

[0115] The filament obtained at zone 18 with a single 3 mm hole outlet was cooled in water and granulated using an SGS 25-E4 granulator (Maag, Oberglatt, Switzerland). Finally, each batch, produced in 1 or 2 kg quantities, was dried overnight in an oven at 60°C and stored in heat-sealed metal bags.

[0116] Injection molded samples

[0117] Injection-molded samples were produced from granules for the characterization of PBSA / essential oil mixtures at minimum and maximum concentrations, i.e., 1 and 5 wt%. The granules of each mixture were injected into a Battenfeld Unilog B2 / 350 Plus injection molding machine (Battenfeld GmbH, Meinerzhagen, Germany) with a 22 mm screw and an L / D ratio of 16. The machine was set with an injection pressure of 120 MPa and a temperature of 120 °C and 25 °C in the barrel and mold, respectively. Standard tensile bars (ISO 527-2, type 1BA) with a width of 5 ± 0.5 mm in the reference area and a thickness of 2 ± 0.2 mm were designed to examine the tensile properties of the mixtures.

[0118] Films

[0119] The films were prepared with granules of each mixture using a Collin Teach-Line E20T single-screw extruder (Maitenbeth, Germany) (L / D = 25, D = 20 mm), at a screw speed of 60 rpm at 120 °C, connected to a Collin Teach-Line BL50T film blowing line with a Collin BL-D blowing die 30x0.8 T. The unwinding speed was adjusted to produce films with a thickness of 80 ± 10 pm, corresponding to those used in plasticulture to cover tunnels or greenhouses.

[0120] The films obtained are thick, smooth, transparent, flexible, without cracks and without bubbles, which is suitable for use as cover films on crops.

[0121] Example 5: Stability of essential oils in PBSA

[0122] Pure essential oils and PBSA granules and PBSA / essential oil mixtures at 1% and 5% by mass were analyzed by thermogravimetric analysis using a Q550 Thermogravimetric Analyzer (TA Instruments, Wakefield, MA, USA). Samples of 6.0 ± 1.0 mg were heated from 30 to 600°C at 10°C / min, under a nitrogen flow of 60 mL / min.

[0123] The thermograms obtained ([Fig.5]) demonstrate a low thermal stability of the pure essential oils and a high thermal resistance of the PBSA.

[0124] Thermograms of the PBSA / essential oil mixtures show a constant and abrupt mass loss, suggesting homogeneous dispersion of the essential oils within the polymer matrix at different concentrations. At a concentration of 1 wt%, the thermograms obtained are similar to those of PBSA, demonstrating improved stability of the essential oils due to their incorporation into PBSA.

[0125] Thus, PBSA / essential oil mixtures have good thermal stability in the operating temperature range.

[0126] Chemical stability studies have also demonstrated that, during the manufacture of the film, the volatile chemical compounds present in the essential oils were successfully included in the PBSA matrix with fairly good stability.

[0127] Example 6: Properties of films according to the invention

[0128] Thermal properties

[0129] To evaluate the effect of essential oils on the properties of PBSA as a function of temperature, PBSA films and PBSA / essential oil mixtures at 1% and 5% wt% were analyzed by DSC (Differential Scanning Calorimetry) using a Q23 calorimeter (TA Instruments, New Castle, DE, USA). Samples of 4.0 ±1.0 mg were stabilized under a nitrogen flow of 50 mL / min at -70 °C, then heated at 10 °C / min to 150 °C and held at this temperature for 2 min to erase previous traces. The samples were then cooled to -70 °C at 10 °C / min, held at this temperature for 2 min, and finally heated to 150 °C at 10 °C / min.

[0130] The following parameters were measured or estimated from the thermograms obtained: glass transition temperature Tg, melting temperature Tm, crystallization temperature Te and percentage of crystallinity Xc.

[0131] The thermal properties of PBSA were not substantially altered by the addition of essential oils. The temperature values ​​(Tg) of the PBSA / essential oil mixtures showed a slight decrease from -47°C to -52°C. The values ​​of temperature (Tm), temperature (Te), and specific gravity (Xc), and the crystalline distribution of the PBSA / essential oil mixtures were comparable to those obtained for pure PBSA, except for the 5% wt% Chinese cinnamon essential oil, which demonstrated a 10°C decrease in temperature (Te) and a change in the crystalline distribution.

[0132] It is possible that the incorporation of essential oils has resulted in a slight plasticization of the PBSA, with a decrease in Tg (and in Te in the case of Chinese cinnamon essential oil).

[0133] Mechanical properties

[0134] Standard PBSA and PBSA / essential oil mixtures at 1% and 5% by weight for each essential oil were subjected to uniaxial tensile testing using an Instron 4301 machine (Norwood, MA, USA) equipped with an optical extensometer and a 30 kN load cell. The initial distance between the jaws was 60 mm. Each sample was marked with two points 20 mm apart in the reduced section for identification by textensometer. The tests were carried out at 22 ± 1°C and 50 ± 5% relative humidity, with a bridgehead speed of 50 mm / min. Five samples were tested for each mixture, and the mean and standard deviation values ​​of Young's modulus, yield strength, and strain at break were obtained using Intron's Bluehill Universal software.

[0135] The PBSA exhibited, as expected, ductile behavior with an average Young's modulus of 290 MPa and a yield strength of 17 MPa. The strain at break is approximately 160%.

[0136] The mechanical properties of the PBSA / essential oils mixtures at 1% by weight were not substantially different from those of pure PBSA, although the deformation at break of the PBSA / Chinese cinnamon essential oil mixture was slightly improved (180%).

[0137] At 5% by weight, the four essential oils tested had a significant effect on the mechanical properties of PBSA, with a decrease in Young's modulus (250 MPa) and yield strength (14 to 16 MPa), and an increase in strain at break (200 to 270%). The effect was particularly pronounced for Chinese cinnamon essential oil, with an average increase in strain at break of 75% compared to 25% for the other essential oils relative to pure PBSA.

[0138] Insect-repellent properties

[0139] Repellent activity was tested with pea aphids (Acyrthosiphonpisum Harris) reared on young plants of Vicia faba L. 'Aquadulce'. The aphids used for the test were one-day-old wingless nymphs (NI) synchronized from wingless adults.

[0140] A choice test was first carried out between a PBSA film and filter paper to confirm the absence of any attractive or repellent effect of PBSA on aphids. The repellent activity of the PBSA / essential oil films was then tested for each essential oil at doses of 1, 2, 3, 4 and 5% by weight.

[0141] The tests were carried out for 24 hours in the dark. The nymphs were placed in the center of a tube (8.33 cm³) sealed at both ends with a complete artificial nutrient regimen coupled to a strip (0.5 x 3 cm) of PBSA film (control) and PBSA / essential oil film (treatment). The aphids had to choose a side by smell and pass under the film strip before settling on the artificial nutrient regimen. The following day, the number of aphids was counted on each side of the tube. The test was repeated 18 times with 5 aphids per tube, for a total of 90 aphids.

[0142] The repellency of the films is shown in the graphs in [Fig. 6]. The percentage of aphids on the control side was well above 50% in all cases, which confirms the strong repellency of the films at all doses and for all essential oils.

[0143] This further confirms that the essential oils were incorporated into the PBSA film without substantial degradation during the manufacturing process.

Claims

Demands

1. Use of a plastic product comprising polybutylene succinate adipate (PBSA) and an insect-repellent active ingredient selected from essential oils, aerial parts of sweet potato plant and mixtures thereof, for the repulsion of pests such as insects.

2. Use according to claim 1, wherein the plastic product is selected from the group consisting of insect netting, agricultural field tarpaulins, plastic tarpaulins, storage bags and gardening pots.

3. Use according to claim 1 or 2, wherein the pests are insects of the family Aphidoidea such as aphids.

4. Use according to any one of claims 1 to 3, wherein the essential oil is selected from the group consisting of basil essential oil, mint essential oil, peppermint essential oil, cinnamon essential oil such as Chinese cinnamon essential oil, marigold essential oil, rosemary essential oil and a mixture thereof.

5. Use according to any one of claims 1 to 4, wherein the plastic product has a thickness of less than 100 micrometers.

6. Use according to any one of claims 1 to 5, wherein the aerial parts of sweet potato are a sweet potato plant leaf puree.

7. Use according to any one of claims 1 to 6, wherein the plastic product comprises at least one other polymer in addition to PBSA, preferably PHB, PHBV or a mixture thereof.

8. Use according to any one of claims 1 to 7, wherein the amount of insect repellent active is 0.5 to 5% by weight relative to the total weight of the PBSA+insect repellent active mixture.

9. Use according to any one of claims 1 to 8, wherein the plastic product is manufactured by a melt-state technique such as extrusion, in particular conventional extrusion or blow molding.

10. Plastic product, in particular plastic film, comprising PBSA and an insect-repellent active ingredient selected from essential oils, aerial parts of sweet potato plant and mixtures thereof.

11. A process for manufacturing a plastic product comprising polybutylene succinate adipate (PBSA) and an insect-repellent active ingredient selected from essential oils, aerial parts of sweet potato plants and mixtures thereof, comprising a melt extrusion step of a mixture comprising polybutylene succinate adipate (PBSA) and the insect-repellent active ingredient.

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