Method for stimulating latex production

Abstract

The invention relates to a method for stimulating the production of latex, characterized in that it comprises a step of applying a sustained-release composition comprising a biocompatible and biodegradable copolyester which can be obtained by polycondensation of at least one dicarboxylic acid monomer and a polyol monomer, and a stimulant for the production of the latex, below the tapping notch, to an area of the previously "scraped" trunk.

Description

[0001] Method for stimulating latex production

[0002] FIELD OF THE INVENTION

[0003] The field of the present invention is that of stimulating the flow of latex from rubber trees, such as Hevea brasiliensis.

[0004] The latex of rubber trees, such as Hevea brasiliensis, is produced by the laticiferous cells, organized into laticiferous vessels, located in the trunk. Incision of the bark using a process called tapping allows the latex to be expelled from the trunk, allowing it to be harvested and used as a raw material for the production of natural rubber. The latter is then processed for use in rubber product formulations. The quantity of latex harvested depends on the frequency of tapping, the flow rate of latex from the tree, and the rate of latex regeneration by the tree. The good health of the tree, from which the quality and quantity of latex produced depend, is therefore crucial.

[0005] Therefore, it is always a concern to aim for sustainable rubber tree exploitation in order to ensure the sustainability of plantations by limiting stress on the trees linked to tapping, while guaranteeing a reduction in production costs. Reducing the frequency of tapping is a practice now widely adopted to reduce production costs. This reduction in tapping frequency, however, leads to a drop in latex yield. To compensate for this drop in yield, chemical stimulants are applied. The most well-known and widespread is an ethylene generator, 2-chloroethylphosphonic acid, known as Ethephon, which can be found, for example, under the trade name Ethrel® (Bayer), formulated in aqueous solution. It is indeed known that latex production is significantly increased when the tree is stimulated by a tiny amount of regularly distributed ethylene.

[0006] Existing products containing Ethephon for application to rubber tree trunks suffer from several drawbacks, both in terms of implementation and their effect on the trees. Commercially available concentrated Ethephon solutions must be diluted in water before brush application to the tree. This dilution must be carried out on site just before application to limit premature degradation of the stimulant in a diluted environment, which exposes operators to the toxicity and corrosiveness of the product. Controlling the amount of product applied to the bark is also difficult with a brush or spray application technique, which also results in product losses to the environment.

[0007] In the past, methods for treating rubber trees have been described with latex production stimulants, using aqueous or non-aqueous liquid formulations containing ethephon and optionally additives (palm oil, ethanol, propylene glycol, acetic anhydride, fatty alcohols, etc.) acting as stabilizers and thickeners to facilitate application. Such methods are, for example, described in GB1281524, GB1320870 or GB1498948.

[0008] These treatment methods cause acute stimulation of latex flow over a short period of time. As a result, the effective annual stimulation period for trees is low. To compensate for this, it is necessary to treat the trees closely with regular stimulant applications throughout the year (estimated at around twenty times a year). These regular applications, depending on the number of trees to be treated, also have a significant impact on production costs because they are time-consuming and expensive. In addition, the climate in tropical and intertropical regions, which is very humid and rainy, regularly leaches the trunks, causing losses of stimulant solution into the environment, leading on the one hand to a reduced stimulation effect but also on the other hand to contamination of the surrounding environment.The long-term impacts of the chemicals in Ethephon solutions, which are toxic and corrosive, on the surrounding environment, the local ecosystem, users and local residents should not be overlooked.

[0009] There is therefore a need to improve the stimulation of latex production, while preserving the good health of the tree and controlling production costs.

[0010] STATEMENT OF THE INVENTION

[0011] The Applicant has developed a process for treating rubber trees that improves the stimulation of latex production by applying to a "scraped" surface of the trunk, under the tapping notch, a composition comprising, on the one hand, a biodegradable and biocompatible polymer, showing a certain antimicrobial activity and, on the other hand, a latex production stimulant, in particular Ethephon. The polymer used is a copolyester of a diacid and a polyol, in particular poly(glycerol sebacate) or PGS. PGS is harmless to the tree and the environment. This composition contains a precise concentration of stimulant and allows a defined quantity of stimulant to be applied in a targeted manner to the tree, limiting losses to the environment due to application techniques and climatic conditions.This composition also allows for a gradual release of the stimulant over time, ensuring continuous and regular stimulation throughout the year, which not only limits tapping frequencies, but also significantly limits stimulation frequencies. Finally, the gradual release allows for continuous stimulation of rubber trees throughout the year, which allows for a significant gain in plot productivity compared to plots stimulated with existing aqueous solutions.

[0012] DESCRIPTION OF FIGURES

[0013] Figure 1: Photographs taken during the test of Example 1 (tree with 2 patches on scraped bark) Figure 2: Photographs taken during the test of Example 1 (tree with 4 patches on scraped bark)

[0014] Figure 3: Photographs taken during the test of example 1 (tree with 2 patches containing wood flour on scraped bark)

[0015] Figure 4: Evolution of cumulative latex production over 6 months.

[0016] Figure 5: Photographs taken during the test of example 2 (tree with 1 patch at t=5 months)

[0017] DEFINITIONS

[0018] By "biocompatible" we mean: something that is tolerated by the body, here in particular something that is tolerated by plants.

[0019] The term "biodegradable" means: capable of being broken down by living organisms.

[0020] For the purposes of the present invention, the term "biodegradable copolyester" means a copolyester that is biodegradable under the cultivation conditions, in particular temperature and humidity, of plants whose treatment falls within the scope of the present invention. Preferably and under these conditions, the term "biodegradable copolyester" means a copolyester that is biodegradable by more than 80% in one year.

[0021] Preferably, for the purposes of the present invention, the term “biodegradable copolyester” means a biodegradable copolyester according to standard EN13432.

[0022] For the purposes of the present invention, the term "patch" means a self-adhesive device in the form of a strip, block or loaf, or any other suitable form, which is made of the gradual release composition.

[0023] In the following description, the names "2-chloroethylphosphonic acid" and "Ethephon" are used interchangeably to designate the same compound.

[0024] SUMMARY OF THE INVENTION

[0025] The invention, described in more detail below, relates to at least one of the embodiments listed in the following points:

[0026] 1. Method for stimulating latex production, characterized in that it comprises a step of applying a gradual release composition comprising a biocompatible and biodegradable copolyester capable of being obtained by the polycondensation of at least one dicarboxylic acid monomer and a polyol monomer, and a latex production stimulant, below the bleeding notch on a previously "scraped" area of ​​the trunk.

[0027] 2. Method according to the preceding embodiment in which the polyol monomer is a triol, preferably glycerol. 3. Method according to any one of the preceding embodiments in which the dicarboxylic acid monomer is a dicarboxylic acid chosen from saturated aliphatic dicarboxylic acids and unsaturated diacids comprising 3 to 36 carbon atoms.

[0028] 4. Process according to any one of the preceding embodiments in which the dicarboxylic acid monomer is an aliphatic dicarboxylic acid corresponding to the formula [HOOC-(CH2)n-COOH], in which n is a number ranging from 1 to 20, preferably a number ranging from 1 to 10.

[0029] 5. Process according to any one of the preceding embodiments in which the dicarboxylic acid monomer is chosen from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or a mixture of two or more of these dicarboxylic acids.

[0030] 6. Method according to any one of the preceding embodiments in which the dicarboxylic acid monomer is chosen from adipic acid, sebacic acid or a mixture of these two dicarboxylic acids.

[0031] 7. A method according to any one of the preceding embodiments wherein the biocompatible and biodegradable copolyester is poly(glycerol sebacate) (PGS), poly(glycerol adipate) (PGA) or poly(glycerol sebacate adipate) (PGSA).

[0032] 8. Method according to any one of the preceding embodiments in which the biocompatible and biodegradable copolyester is biosourced.

[0033] 9. Method according to any one of the preceding embodiments in which the biocompatible and biodegradable copolyester has a number average molar mass of 800 g / mol to 3000 g / mol, preferably of 800 g / mol to 2800 g / mol.

[0034] 10. Method according to any one of the preceding embodiments in which the biocompatible and biodegradable copolyester has a number average molar mass of from 1000 g / mol to 2000 g / mol.11.

[0035] 11. Method according to any one of the preceding embodiments, in which the latex production stimulant is an ethylene generator.

[0036] 12. A method according to any one of the preceding embodiments, wherein the latex production stimulant is Ethephon.

[0037] 13. A method according to any one of the preceding embodiments wherein the biocompatible and biodegradable copolyester is poly(glycerol sebacate) (PGS), poly(glycerol adipate) (PGA) or poly(glycerol sebacate adipate) (PGSA) and the latex production stimulant is Ethephon. 14. A method according to any one of the preceding embodiments wherein the content of biocompatible and biodegradable copolyester in the composition is within a range from 20% by mass to 90% by mass of the total mass of the composition.

[0038] 15. Method according to any one of the preceding embodiments in which the stimulant content in the composition is within a range from 2% by mass to 10% by mass of the total mass of the composition.

[0039] 16. A method according to any one of the preceding embodiments wherein the composition comprises a stimulant solvent, preferably water.

[0040] 17. Method according to any one of the preceding embodiments in which the composition comprises water in a content within a range from 1% to 30% by weight, preferably from 2% to 20% by weight, particularly preferably 5% to 15% by weight of the total weight of the composition.

[0041] 18. Method according to any one of the preceding embodiments comprising one or more additives chosen from the group consisting of fillers, stabilizers, compatibilizing agents, shaping agents, regulators of release of the active ingredient, antioxidants, phytosanitary agents.

[0042] 19. Method according to any one of the preceding embodiments comprising a plant filler in a content ranging from 5% to 40% by weight, preferably from 8% to 30% by weight, relative to the total weight of the composition.

[0043] 20. Method according to the preceding embodiment in which the plant load has a median particle size of between 20 and 700 microns.

[0044] 21. Method according to any one of embodiments 19 and 20 in which the vegetable filler comprises a wood flour.

[0045] 22. Method according to any one of embodiments 19 to 21 in which the vegetable filler is a wood flour.

[0046] 23. Method according to any one of the preceding embodiments in which the composition is applied in the form of a preformed and / or pre-cut patch.

[0047] 24. Method according to any one of embodiments 1 to 22 in which the composition is applied in the form of a paste or a coating by means of an application device among a spatula, a brush, a brush or an extrusion device. 25. Method according to any one of the preceding embodiments in which the composition is applied at a distance of at most 20 cm below the groove.

[0048] 26. Method according to any one of the preceding embodiments in which the composition is applied at a distance of at least 4 cm below the bleeding notch.

[0049] 27. Method according to any one of the preceding embodiments in which the composition is applied to a previously "scraped" area of ​​the trunk located 4 cm to 20 cm, preferably 5 cm to 15 cm below the bleeding notch.

[0050] DETAILED DESCRIPTION OF THE INVENTION

[0051] The invention relates to a method for stimulating latex production comprising the application below the bleeding notch on a previously "scraped" area of ​​the trunk, of a gradual release composition comprising a biocompatible copolyester obtainable by the polycondensation of a dicarboxylic acid monomer and a polyol monomer, and a latex production stimulant.

[0052] I - Composition

[0053] Co-polyesters

[0054] The composition used in the method according to the invention comprises a biodegradable and biocompatible copolyester. The copolyester is capable of being obtained by the polycondensation of a dicarboxylic acid monomer and a polyol monomer.

[0055] The copolyesters according to the invention are polyesters composed of at least two different units, derived from at least one dicarboxylic acid and at least one polyol.

[0056] The term "polyol" is understood to mean, within the meaning of the present invention, an organic molecule comprising at least two alcohol functions, preferably at least three alcohol functions. Preferably, the polyol is preferably a triol, more preferably glycerol.

[0057] The dicarboxylic acid monomer according to the invention may be aliphatic, aromatic or aliphatic / aromatic. In the latter case, the diacid comprises an aliphatic part and an aromatic part. It preferably comprises from 3 to 36 carbon atoms. Aliphatic means linear, cyclic or branched aliphatic, whether saturated or unsaturated.

[0058] According to preferred variants of the invention, the dicarboxylic acid monomer is aliphatic comprising 3 to 36 carbon atoms. According to these variants, the dicarboxylic acid monomer is preferably chosen from saturated aliphatic dicarboxylic acids and unsaturated diacids, preferably (C3-C2o)alkyldiacids, more preferably (Cs-Csjalkyldiacids. More particularly, the dicarboxylic acid may preferably correspond to the formula [HOOC-(CH2)n-COOH], in which n is a number ranging from 1 to 20, preferably a number ranging from 1 to 10.

[0059] Preferably, according to these variants of the invention, the dicarboxylic acid monomer may be chosen from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and a mixture of two or more of these dicarboxylic acids. According to variants of the invention, the dicarboxylic acid monomer is chosen from adipic acid, sebacic acid or a mixture of these two dicarboxylic acids.

[0060] According to variants of the invention, the dicarboxylic acid monomer comprises sebacic acid.

[0061] The biocompatible and biodegradable copolyester is advantageously poly(glycerol sebacate) (PGS), poly(glycerol adipate) (PGA) or their derivatives, more preferably poly(glycerol sebacate) (PGS), poly(glycerol adipate) (PGA) or poly(glycerol sebacate adipate) (PGSA). According to one embodiment, the biocompatible and biodegradable copolyester is poly(glycerol sebacate) (PGS).

[0062] The molar ratio (polyol monomer) / (dicarboxylic acid monomer) for the synthesis of the copolyester, and in particular the molar ratio of glycerol / dicarboxylic acid monomer, is advantageously between 0.3:1 and 1:0.3.

[0063] The copolyester can be obtained in a known manner using a two-step synthesis: a first esterification step and a second polycondensation step, and possibly a 3 èmecrosslinking step. The first step consists of an esterification reaction between an acid function of the dicarboxylic acid and an alcohol function of the polyol. The second step consists of growing the chains to obtain a resin by polycondensation.

[0064] Then, different strategies can be used to adjust the polymer properties, such as long thermal crosslinking by esterification of the pendant secondary alcohol functions (often at high temperature and low pressure), or crosslinking via post-functionalization (such as functionalization of the polymer matrix, such as acrylate or methacrylate functions, followed by radical crosslinking or crosslinking with isocyanates, such as hexamethylenediamine diisocyanate). It is also possible to carry out copolymerization of the copolyester with blocks of other linear polymers, for example with polylactic acid (PLA), poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL) or poly(butyl succinate) (PBS).For the purposes of the present invention, all of these compounds are grouped under the name copolyester or more specifically poly(glycerol sebacate) or poly(glycerol adipate) and their derivatives.

[0065] For example, document WO2015 / 184313A1 describes the synthesis of poly(glycerol sebacate). The Applicant has also described syntheses of copolyesters in applications FR2303707, FR2303705 and FR2305666. Furthermore, PGS is commercially available, in particular under the name Regenerez® Poly(glycerol sebacate) Resin.

[0066] Preferably according to the invention, the biodegradable and biocompatible copolyester is biosourced. That is to say that the copolyester is partially or totally derived from biomass or obtained from renewable raw materials derived from biomass.

[0067] According to certain embodiments of the invention, the copolyester preferably has a number-average molar mass (Mn) in a range from 800 g / mol to 3000 g / mol, preferably from 800 g / mol to 2800 g / mol. In the Mn range from 800 g / mol to 3000 g / mol, the copolyester provides sufficient tack to the composition according to the invention to be able to adhere to the scraped surface of the trunk. According to certain embodiments, the copolyester preferably has a number-average molar mass (Mn) varying from 1000 g / mol to 2000 g / mol.

[0068] Mn is measured by size exclusion chromatography (SEC) described below in the examples.

[0069] Thus, according to a particularly preferred embodiment of the synthesis process according to the invention, the biocompatible and biodegradable copolyester is poly(glycerol sebacate) (PGS), poly(glycerol adipate) (PGA) or poly(glycerol sebacate adipate) (PGSA), preferably biosourced, having a number-average molar mass (Mn) varying from 1000 g / mol to 2000 g / mol.

[0070] The composition used in the process according to the invention advantageously comprises up to 90% by weight, preferably from 20% to 90% by weight, more preferably 30% to 90% by weight, more preferably 40% to 90% by weight of a biodegradable and biocompatible copolyester capable of being obtained by the polycondensation of a diacid monomer and a polyol monomer.

[0071] Latex production stimulant

[0072] The composition used in the method for stimulating latex production according to the invention also comprises a latex production stimulant.

[0073] According to the invention, any type of stimulant known for its effect on latex production by rubber trees can be used. 2-Chloroethylphosphonic acid (or Ethephon) is, among others, an agent that stimulates latex production by rubber trees. This is the stimulant that is preferred according to the invention, for reasons of availability and for its particularly effective and recognized stimulating action on latex production.

[0074] The person skilled in the art knows the annual doses that a tree can receive, in particular depending on the clone and its age, and will know how to dose the stimulant. Nevertheless, the composition used in the method according to the invention advantageously comprises from 2% to 10% by weight of the total weight of the composition of latex production stimulant. In this field, the composition according to the invention then has sufficient stickiness without the addition of a specific additive to be able to adhere to the scraped surface of the trunk.

[0075] The composition used in the method according to the invention may comprise, in certain embodiments, a solvent for the stimulant and in particular water. When the composition contains water, the latter is present in a content ranging from 1% to 30% by weight, preferably from 2% to 20% by weight, particularly preferably 5% to 15% by weight of the total weight of the composition in order to limit the flow of the composition on the trunk.

[0076] Those skilled in the art will understand that the quantity of water in the composition according to the invention depends in particular on the dilution rate and the desired quantity of stimulant in the composition.

[0077] According to a preferred embodiment of the method of the invention, in order to optimize the stickiness of the composition without using a specific additive, the composition comprises a copolyester, in particular a PGS, having a number-average molar mass (Mn) varying from 1000 g / mol to 2000 g / mol and from 2% to 10% by weight of the total weight of the composition of latex production stimulant, in particular Ethephon.

[0078] Additives

[0079] The composition used in the method according to the invention may comprise at least one phytosanitary active ingredient and / or a biostimulant. The active ingredient is preferably chosen from the group consisting of stimulants, fertilizers, pesticides, fungicides, nutrients, bactericides, insecticides, growth regulators.

[0080] The composition used in the method according to the invention may comprise one or more additives chosen in particular from the group consisting of stabilizers, compatibilizing agents, shaping agents, stimulant release regulators, antioxidants, fillers.

[0081] According to one embodiment of the invention, the composition according to the invention comprises a plant filler. According to this embodiment, the creep resistance of the composition applied to the trunk of the rubber tree according to the invention, subjected to the temperatures of tropical or subtropical zones, can be improved without degradation of the adhesion to the trunk of the treated trees. According to the invention, the term "plant filler" means a filler comprising lignocellulosic particles or a mixture composed essentially of lignocellulosic particles.

[0082] Lignocellulose is a combination of lignin, hemicellulose, and cellulose found in the form of fibers in plant cell walls. Lignocellulosic fibers include wood fibers and fibers from cultivated plants. These include fibers extracted from trunks or stems (coconut trunks, banana stems, bamboo), straw, fibers extracted from leaves, and fibers extracted from seeds or fruits (cotton).

[0083] According to one embodiment of the invention, the plant filler consists of particles whose median size is less than one millimeter. Preferably, according to this embodiment of the invention, the plant filler consists of particles whose median size is in a range from 20 to 700 microns.

[0084] Thus, the lignocellulosic material used as plant filler is finely ground to this particle size using known grinding processes adapted to each material.

[0085] A major advantage of using this type of material is its reduced impact on the environment and its biodegradability in natural conditions.

[0086] According to a particular embodiment of the invention, the plant filler comprises wood flour, also called wood powder. Very preferably, the plant filler consists essentially of wood flour.

[0087] Preferably, when the composition according to the invention comprises a plant filler, its content is at least 5% by weight relative to the total weight of the composition. According to certain embodiments, the composition then comprises from 5% to 40% by weight of a plant filler, preferably from 10% to 40% by weight, more preferably from 15% to 30% by weight, relative to the total weight of the composition.

[0088] Production of the composition

[0089] Various methods of formulating the copolyester with the stimulant may be employed to make the composition used in the method of the invention. Examples include, but are not limited to, a mixture of molten copolyester with the stimulant in solution, for example, in aqueous solution.

[0090] This mixture can be carried out in a conventional stirred reactor at relatively mild temperatures to limit the risks of degradation of the stimulant, preferably below 120°C, preferably below 110°C, preferably below 100°C, using conventional rotors or ultraturax shearing rotors while limiting the contact time. The mixing process can be batch, semi-batch or continuous. II - Application step

[0091] Application area

[0092] According to the method of the invention, the composition as described above is applied to a previously scraped area of ​​the trunk.

[0093] As is known, in order to ensure the assimilation of a latex production stimulant, it can be applied to the area of ​​the bleeding notch or to a previously scraped area of ​​the trunk.

[0094] For the purposes of this description, "scraping" means scraping or brushing the surface of the trunk to locally remove lichens and layers of dead cells from the bark. This scraping technique is known to those skilled in the art.

[0095] According to the method of the invention, the composition as described above is applied to a previously scraped area of ​​the trunk which is located below the bleeding notch. The Applicant has in fact found that the effect on latex production is maximum when the composition is applied in this area of ​​the tree on a previously scraped area of ​​the trunk.

[0096] The Applicant has demonstrated that applying the composition to another area of ​​the tree and without prior brushing of the area does not give the desired technical effect. A deterioration in the effectiveness of stimulation of the tree is then observed compared to the method according to the invention.

[0097] According to an advantageous embodiment of the method of the invention, the composition is applied to a previously scraped area of ​​the trunk which is located at least 4 cm below the bleeding notch.

[0098] According to an advantageous embodiment of the method of the invention, the composition is applied to a previously scraped area of ​​the trunk which is located at most 20 cm below the bleeding notch.

[0099] Very preferably according to these variants of the method of the invention, the composition is applied to a previously scraped area of ​​the trunk which is located at least 4 cm and at most 20 cm, preferably at least 5 cm and at most 15 cm below the bleeding notch, the application area forming a band parallel to the bleeding notch.

[0100] Form of the composition

[0101] The composition useful for the purpose of the invention is formulated to be sticky and adhere to the trunk of the tree to be treated. The composition useful for the purpose of the invention is applied in an effective amount. This amount depends on the variety of the tree, its age, its size and the frequency of tapping, as well as the concentration of latex flow stimulant in the composition. According to one implementation of the method of the invention, the amount of stimulant, in particular Ethephon, is generally of the order of 0.1 g to 1 g per tree per year.

[0102] According to the invention, the composition intended to be applied to the trunk of trees may be in the form of a paste or coating to be spread with a spatula, brush or paintbrush. The composition then forms a layer on the area of ​​application of the trunk, previously scraped.

[0103] When the composition is in the form of a paste or coating, it is also possible to envisage application by means of a device for extruding the composition contained in a cartridge or other type of reservoir, under pressure or not, allowing the desired quantity of composition to be delivered. For example, a device such as a mastic gun can be mentioned, allowing a controlled application of a mass to the trunk.

[0104] According to an advantageous implementation of the method of the invention, the composition is applied in the form of a preformed and / or precut patch. This is a piece of paste preformed and / or precut to suitable dimensions, which naturally adheres to the application area. This piece of paste can be of different shapes, such as in the form of a strip or band, in the form of a loaf or block (in the form of a disc or pellet for example).

[0105] The advantage of this application method is that the patch contains a precise concentration of stimulant and allows a specific amount of stimulant to be applied to the shaft in a targeted manner. This is not the case with application with a spatula, brush or brush.

[0106] The patch has excellent adhesion performance on the trunk, good resistance to climatic hazards (wind, mechanical and biological attacks, rain, etc.) and therefore helps to limit losses in the environment due to application techniques and climatic conditions.

[0107] A device composed of a “hard” layer in contact with a “sticky” layer of the preformed and / or pre-cut bilayer patch type according to suitable dimensions can also be considered.

[0108] The method of the invention allows continuous stimulation of Hevea brasiliensis throughout the year, which allows a gain in latex production of the plots compared to plots stimulated with aqueous solutions in a conventional manner. More precisely, a cumulative latex production over 90 days is noted for the trees stimulated with a composition comprising PGS and Ethephon according to the invention, at least as high as the latex production of trees stimulated according to the conventional stimulation method, or even higher by 10%.

[0109] The increase in latex production from trees makes it possible to envisage a reduction in the frequency of tapping, leading to a significant reduction in the operating cost of rubber plots, as well as a significant reduction in the stress inflicted on the trees by repeated tapping and an improvement in their health.

[0110] Furthermore, the biodegradable nature of the copolyester capable of being obtained by the polycondensation of at least one dicarboxylic acid and a polyol, not requiring the implementation of a process for recovering the composition layers at the end of their life.

[0111] It goes without saying that this method of stimulating latex production according to the invention can be adapted to other species exploited by tapping and which are sensitive to stimulation by an ethylene generator such as Ethephon. We can thus cite for example the production of gum arabic from acacias (Acacia Senegal and Acacia seyal).

[0112] EXAMPLES

[0113] The following examples illustrate the invention without limiting its scope.

[0114] 1. Measurement methods used to characterize the polymer composition:

[0115] 1.1 Determination of the microstructure of PGS polymers:

[0116] The microstructure of the polymers is determined by 1H NMR analysis, supplemented by 13C NMR analysis when the resolution of 1H NMR spectra does not allow the attribution and quantification of all species. The measurements are carried out using a BRUKER 500MHz NMR spectrometer at frequencies of 500.43 MHz for proton observation and 125.83MHz for carbon observation.

[0117] 1.2 Determination of the macrostructure of PGS polymers:

[0118] The SEC (Size Exclusion Chromatography) technique separates macromolecules in solution according to their size through columns filled with a porous gel. The macromolecules are separated according to their hydrodynamic volume, with the largest being eluted first.

[0119] Although not an absolute method, SEC allows us to understand the distribution of molar masses of a polymer. From commercial standard products, the different number-average (Mn) and weight-average (Mw) molar masses can be determined and the polydispersity index (D = Mw / Mn), also called "dispersity", calculated.

[0120] Size exclusion chromatography analyses were performed using a Viscotek instrument (Malvern Instruments) equipped with 3 columns (SDVB, 5 μm, 300 x 7.5 mm of Polymer Standard Service), a guard column, and 3 detectors (differential refractometer and viscometer, and light scattering). 1 mL of a solution of the sample with a concentration of 5 mg mL-1 in THF was filtered through a 0.45 μm PTFE membrane. 100 pL of this solution was eluted in THF using a flow rate of 0.8 mL min-1 at a temperature of 35 °C. OmniSEC software was used for data acquisition and analysis. The number (Mn) and mass (Mw) molar masses of the polymers as well as their dispersity (D) were calculated using a calibration curve from standard polystyrenes (Mw: 1,306 to 2,520,000 g mol-1) from Polymer Standard Service (Mainz).

[0121] 2. Synthesis of polymer according to the invention

[0122] 2.1. Example 1

[0123] In a 500 mL double jacketed reactor topped with a distillation column configured for total reflux and a condenser connected to a distillation recovery vessel, glycerol (124 g, 1.5 molar equiv.) is mixed with water (24 g) at room temperature under nitrogen flow (0.1 L / min). Gentle stirring is implemented (50 rpm) for 5 min. After dissolution of the glycerol, sebacic acid (182 g, 1 molar equiv.) is added to the aqueous mixture in the reactor. Finally, the remaining water is added to the medium (24 g). The reactor vessel is then heated to a jacket temperature of 140 °C. Stirring is gradually increased to 100 rpm and then 150 rpm with the melting and increasing solubilization of the acid. When the medium in the tank has become clear (around 95°C), the stirring is increased to a final value of 200 rpm and the medium left to reflux.When the vapor temperature at the top of the distillation column reaches 98°C, and after an equilibration time of 15 min, the column configuration is switched to total withdrawal. Esterification of the medium is carried out over a period of 26 hours. The water distilled during the test is recovered in a dedicated heat-insulated recovery pot.

[0124] Next, a vacuum system is connected to the distillation condenser and a pressure below atmospheric pressure is applied to the reactor contents. The pressure is reduced slowly and stepwise (approximately 10 to 15% per step) over approximately 30 minutes to a target value of less than 10 mbar.

[0125] Once the pressure in the reaction vessel stabilizes at 5 mbar, the medium is left to react at 150 °C for an additional 3 h. During this polycondensation step, the stirring speed is reduced to 115 rpm to account for the increased viscosity of the mixture.

[0126] The produced PGS is transferred from the reactor vessel to a container after the facility has been depressurized and allowed to cool to room temperature. The product is then transferred to a freezer for storage, where it is frozen for at least approximately 24 hours before analysis.

[0127] The resulting polymer has the following characteristics:

[0128] 2.2 Example 2:

[0129] In a 500 mL double jacketed reactor topped with a distillation column configured for total reflux and a condenser connected to a distillation recovery vessel, glycerol (124 g, 1.5 molar equiv.) is mixed with water (24 g) at room temperature under nitrogen flow (0.1 L / min). Gentle stirring is implemented (50 rpm) for 5 min. After dissolution of the glycerol, sebacic acid (182 g, 1 molar equiv.) is added to the aqueous mixture in the reactor. Finally, the remaining water is added to the medium (24 g). The reactor vessel is then heated to a jacket temperature of 140 °C. Stirring is gradually increased to 100 rpm and then 150 rpm with the melting and increasing solubilization of the acid. When the medium in the tank has become clear (around 95°C), the stirring is increased to a final value of 200 rpm and the medium left to reflux.When the vapor temperature at the top of the distillation column reaches 98°C, and after an equilibration time of 15 min, the column configuration is switched to total withdrawal. Esterification of the medium is carried out over a period of 25 h. The water distilled during the test is recovered in a dedicated heat-insulated recovery pot.

[0130] Next, a vacuum system is connected to the distillation condenser and a pressure below atmospheric pressure is applied to the reactor contents. The pressure is reduced slowly and stepwise (approximately 10 to 15% per step) over approximately 30 minutes to a target value of less than 10 mbar.

[0131] Once the pressure in the reaction vessel stabilizes at 5 mbar, the medium is left to react at 150 °C for an additional 5 h. During this polycondensation step, the stirring speed is reduced to 115 rpm to account for the increased viscosity of the mixture.

[0132] The produced PGS is transferred from the reactor vessel to a container after the facility has been depressurized and allowed to cool to room temperature. The product is then transferred to a freezer for storage, where it is frozen for at least approximately 24 hours before analysis.

[0133] The resulting polymer has the following characteristics:

[0134] 2.3 Example 3:

[0135] In a 10L double-jacketed stainless steel reactor topped with an instrumented distillation column configured in total reflux and a condenser connected to a distillate recovery pot, glycerol (2.0 kg, 1.05 molar equiv.) is mixed with water (0.56 kg) at 40 °C under nitrogen flow (0.5 L / min). Gentle stirring is implemented (20 rpm) for 5 min. After dissolution of the glycerol, sebacic acid (4.2 kg, 1 molar equiv.) is added to the aqueous mixture in the reactor. Finally, the remaining water is added to the medium (0.55 kg). The reactor vessel is then gradually heated, following a gradual temperature rise ramp with intermediate stages, until a jacket temperature of 170°C is reached after 3 hours, corresponding to a medium temperature of 160°C, measured using an immersion probe. Stirring is increased to 80 rpm when the medium temperature exceeds 90°C. The medium is left at reflux at the start of the test.When the temperature of the vapors at the top of the distillation column reaches 98°C, and after an equilibration time of 15 min, the column configuration is switched to total withdrawal in order to selectively recover the water produced during the reaction.

[0136] The esterification of the medium is carried out over a total period of 7 hours at 160°C, taking as the starting point the moment when distillation begins, i.e. approximately 30 minutes after the introduction of the reagents. The water distilled during the test is collected in a dedicated heat-insulated recovery pot.

[0137] The produced PGS is transferred from the reactor vessel to a container and allowed to cool to room temperature. The product is then transferred to a freezer for storage, where it is frozen for at least approximately 24 hours before analysis.

[0138] The resulting polymer has the following characteristics: 2.4. Example 4:

[0139] In a 500 mL double jacketed reactor topped with a distillation column configured for total reflux and a condenser connected to a distillation recovery pot, glycerol (231 g, 3 molar equiv.) is mixed with water (36 g) at room temperature under nitrogen flow (0.1 L / min). Gentle stirring is implemented (50 rpm) for 5 min. After dissolution of the glycerol, sebacic acid (168 g, 1 molar equiv.) is added to the aqueous mixture in the reactor. Finally, the remaining water is added to the medium (36 g). The reactor vessel is then heated to a jacket temperature of 140 °C. Stirring is gradually increased to 100 rpm and then 150 rpm with the melting and increasing solubilization of the acid. When the medium in the tank has become clear (around 95°C), the stirring is increased to a final value of 200 rpm and the medium left to reflux.When the vapor temperature at the top of the distillation column reaches 98°C, and after an equilibration time of 15 min, the column configuration is switched to total withdrawal. Esterification of the medium is carried out over a period of 24 hours. The water distilled during the test is collected in a dedicated heat-insulated recovery pot.

[0140] Next, a vacuum system is connected to the distillation condenser and a pressure below atmospheric pressure is applied to the reactor contents. The pressure is reduced slowly and stepwise (approximately 10 to 15% per step) over approximately 30 minutes to a target value of less than 10 mbar.

[0141] Once the pressure in the reaction vessel stabilizes at 5 mbar, the medium is left to react at 140 °C for an additional 3 h. During this polycondensation step, the stirring speed is reduced to 115 rpm to account for the increased viscosity of the mixture.

[0142] The produced PGS is transferred from the reactor vessel to a container after the facility has been depressurized and allowed to cool to room temperature. The product is then transferred to a freezer for storage, where it is frozen for at least approximately 24 hours before analysis.

[0143] The resulting polymer has the following characteristics: 3. Preparation of the composition according to the invention

[0144] 3.1. Example 1

[0145] In a 500 mL double-jacketed reactor, PGS (210 g) obtained in Example 2.1 was melted at 50 °C under an inert atmosphere for 30 min with stirring. A commercial ethephon solution containing 480 g / L of 2-chloroethyl phosphonic acid was then added using a pump (30.3 g) over a period of 5 min. The medium was left to stir for an additional 30 min, then the composition was transferred from the reactor vessel to silicone molds used to manufacture 1 g circular pellets. The molds were left to cool at room temperature for 24 h, until a white crystallized composition was obtained. The patches were removed from the mold and individually packaged between Teflon sheets. The patches are of the following composition: 5%w / w 2-chloroethyl phosphonic acid, 7.6%w / w water and 87.4%w / w PGS.

[0146] 3.2. Example 2

[0147] In a 500 mL double-jacketed reactor, PGS (225 g) obtained in Example 2.2 was melted at 50 °C under an inert atmosphere for 30 min with stirring. A commercial ethephon solution containing 480 g / L of 2-chloroethyl phosphonic acid was then added using a syringe (15.1 g) over a period of 2 min. The medium was left to stir for an additional 30 min, then the composition was transferred from the reactor vessel to silicone molds used to manufacture 1 g circular pellets. The molds were left to cool at room temperature for 24 h, until a white crystallized composition was obtained. The patches were removed from the mold and individually packaged between Teflon sheets. The patches are of the following composition: 2.5%w / w 2-chloroethyl phosphonic acid, 3.8%w / w water and 93.7%w / w PGS.

[0148] 3.3. Example 3

[0149] In a 500 mL double-jacketed reactor, PGS (201 g) obtained in Example 2.2 was melted at 50 °C under an inert atmosphere for 30 min with stirring. A commercial ethephon solution containing 480 g / L of 2-chloroethyl phosphonic acid was then added using a syringe (15.1 g) over a period of 2 min, along with wood flour (24 g). The medium was left to stir for a further 30 min, then the composition was transferred from the reactor vessel to a silicone plate which was left to cool at room temperature for 24 h, until a beige crystallized composition was obtained. The composition was then calendered into a 3 mm thick paste and punched into round patches of 20 mm diameter with a mass of 1 g. The patches were finally individually packaged between Teflon sheets. The patches are of the following composition: 2.5%w / w 2-chloroethyl phosphonic acid, 3.8%w / w water, 10%w / w wood flour and 83.7%w / w PGS.

[0150] 3.4. Example 4 In a Speedmixer planetary mixer jar, PGS (105 g) obtained in Example 2.3 and previously heated to 50 °C for 4 hours under an inert atmosphere is mixed with a commercial ethephon solution containing 480 g / L of 2-chloroethyl phosphonic acid (15.1 g). The composition is mixed twice for 2 minutes at 3000 rpm. The composition is then transferred from the reactor vessel to silicone molds used to produce 1 g circular pellets. The molds are left to cool at room temperature for 24 hours, until a white crystallized composition is obtained. The patches are removed from the mold and individually packaged between Teflon sheets. The patches are of the following composition: 5%w / w 2-chloroethyl phosphonic acid, 7.6%w / w water and 87.4%w / w PGS.

[0151] 3.5. Example 5

[0152] In a 500 ml double-jacketed reactor, PGS (210 g) obtained in Example 2.4 was melted at 50 °C under an inert atmosphere for 30 min with stirring. A commercial ethephon solution containing 480 g / L of 2-chloroethyl phosphonic acid was then added using a pump (30.3 g) over a period of 5 min. The medium was left to stir for a further 30 min, then the composition was transferred from the reactor vessel to silicone molds used to manufacture 1 g circular pellets. The molds were left to cool at room temperature for 24 h, until a white crystallized composition was obtained. The patches were removed from the mold and individually packaged between Teflon sheets. The patches are of the following composition: 5%w / w 2-chloroethyl phosphonic acid, 7.6%w / w water and 87.4%w / w PGS.

[0153] 4. Field stimulation trials

[0154] 4.1. Examples according to the invention

[0155] The test is carried out in a plot of Hevea brasiliensis. Each treatment consists of 5 trees. The tapping system includes a tapping every 6 days. Harvesting is carried out at the bottom of the cup 3 days after tapping, i.e. after coagulation of the latex produced. The patches manufactured according to the invention are applied to an area or strip located 5 cm to 10 cm below the tapping notch which has previously been scraped using a scraper to remove lichens and the first layers of dead cells without causing the latex to flow, as illustrated in Figures 1, 2 and 3. The patches were placed on the trunk on May 30 and the duration of the test is 5 months.

[0156] The treatments considered consist of applying, per tree:

[0157] 4 patches of 1g at 5%w / w of 2-chloroethyl phosphonic acid, or 4g of composition per tree (from example 3.1). This treatment will be called 4.1.T8; (Figure 2)

[0158] 4 patches of 1g at 2.5%w / w of 2-chloroethyl phosphonic acid, i.e. 4 g of composition per tree (from example 3.2). This treatment will be called 4.1.T6 2 patches of 1g at 2.5%w / w of 2-chloroethyl phosphonic acid, i.e. 2 g of composition per tree (from example 3.3). This treatment will be called 4.1.T9 (Figure 1)

[0159] 2 patches of 1g at 5%w / w of 2-chloroethyl phosphonic acid, i.e. 2g of composition per tree (from example 3.4). This treatment will be called 4.1.T7 (Figure 3)

[0160] 2 patches of 1g at 5%w / w of 2-chloroethyl phosphonic acid, i.e. 2g of composition per tree (from example 3.5). This treatment will be called 4.1.T3

[0161] The results of coagulated latex production are reported in Tables 1 and 2 and the graph in Figure 4 of the evolution of the production of coagulated latex recovered by treatment as a function of time for these examples.

[0162] 4.2. Example 2 not in accordance with the invention

[0163] A commercial solution of Hévétex containing 10% w / w 2-chloroethyl phosphonic acid is diluted to 2.5% w / w by adding water. This solution is applied to the tapping notch with a brush at a frequency recommended by those skilled in the art, i.e. at least once or twice a month, as indicated in Table 1. This treatment consists of 5 trees. The tapping system includes a tapping every 6 days. Harvesting is carried out at the bottom of the cup 3 days after tapping, i.e. after coagulation of the latex produced. The duration of the trial is 5 months, the first stimulation was carried out on May 30.

[0164] The results of coagulated latex production are reported in Tables 1 and 2 and the graph in Figure 4.

[0165] 4.3. Example 3 not in accordance with the invention

[0166] A reference example is to not perform any stimulation on a group of 5 trees for the entire duration of the test. The tapping system involves tapping every 6 days. Harvesting is carried out at the bottom of the cup 3 days after tapping, i.e. after coagulation of the latex produced. The duration of the test is 5 months. This example will be referred to as 4.3.

[0167] The results of coagulated latex production are reported in Tables 1 and 2 and the graph in Figure 4.

[0168] 4.4. Example 4 not in accordance with the invention

[0169] The test is carried out in a plot of Hevea brasiliensis. Each treatment consists of 10 trees. The tapping system includes a tapping every 6 days. Harvesting is carried out at the bottom of the cup 3 days after tapping, i.e. after coagulation of the latex produced. Patches manufactured according to Example 3.2. were used according to a method not in accordance with the invention by positioning them as follows:

[0170] 3 patches of 1g at 2.5%w / w of 2-chloroethyl phosphonic acid, or 3 g of composition per tree, were positioned on unscraped bark under the tapping notch. This treatment will be called 4.4.T2; 3 patches of 1g at 2.5%w / w of 2-chloroethyl phosphonic acid, or 3 g of composition per tree, were positioned on scraped bark above the tapping notch, on the tapping panel. This treatment will be called 4.4.T3;

[0171] 3 patches of 1g at 2.5%w / w of 2-chloroethyl phosphonic acid, or 3g of composition per tree, were positioned on unscraped bark above the tapping notch, on the tapping panel. This treatment will be called 4.4.T4.;

[0172] The patches were fixed on the tree on November 4 and the trial duration is 1.5 months.

[0173] The results of coagulated latex production are reported in Table 3.

[0174] Table 1: Mass of coagulated latex recovered per treatment as a function of time Table 2: Cumulative coagulated latex mass recovered per treatment as a function of time Table 3: Mass of coagulated latex recovered per treatment as a function of time for non-compliant examples 4.4.T2, 4.4.T3 and 4.4.T4.

[0175] It can be noted that the non-compliant example 4.3. shows a low production of coagulated latex over the test period with a cumulative production of 6.6 kg over the period for the 5 trees. It is necessary to increase the tapping frequency < 6 days, such as every 3 days, or even every 2 days, to increase production.

[0176] Example 4.2 was carried out under conditions known to those skilled in the art and therefore not in accordance with the invention, with 7 stimulations carried out over the period of the test, as visible in graphs 1 and 2, where peaks of coagulated latex production are systematically distinguished after each stimulation, and a rapid drop in the level of production a few days after each stimulation, with an effect on the production of coagulated latex limited at best to 3 tappings. The mass of coagulated latex harvested at the end of the test after 5 months amounts to 16.25 kg for the 5 trees.

[0177] Examples 4.4. were carried out using the compositions described in the invention but not using the application method according to the invention. When the patch or strip is not positioned under the tapping notch on a previously scraped trunk, the effect of the stimulation is limited, with an increase in latex production which is only visible for less than 20 days after the patches are placed, i.e. an effect on production which is at best only 3 tappings. Examples 4.1. were carried out according to the invention, using the compositions described in the invention and applying the patches 5 to 10 cm under the tapping notch, having previously scraped the bark to remove lichens and the first layers of dead cells. Example 4.1.T8 shows in particular a strong initial stimulation of the trees, with a level of coagulated latex production greater than 1 kg for at least 20 days, then a progressive decrease.At the end of the test after 5 months, 17 kg of coagulated latex could be harvested, i.e. a cumulative production of coagulated latex 4.6% higher than in Example 4.2, as illustrated in Graph 2. This example shows that with the device according to the invention, it is not necessary to conduct regular stimulation rounds to achieve a production level almost 5% higher after 5 months. The cumulative production is even 67% higher after 1 month, 35% after 2 months and 21% after 3 months, as summarized in the table below.

[0178] The other examples 4.1 also show strong initial stimulations and a progressive decrease, with variations linked to the type of polymer used, the concentration of ethephon present in the patch and the quantity of patches deposited on the trees.

[0179] As illustrated in Table 4 below, example 4.1.T7 maintains a higher production than reference 4.2 after 3 months (gain of 4.7%), examples 4.1.T6, 4.1.1.T9 and 4.1.T3 achieve a higher production of respectively 11.5%, 3.8% and 1.6% after 2 months compared to reference 4.2.

[0180] Table 4:

[0181] Finally, at the end of the test after 5 months, 85% of the patches of examples 4.1.T8, 4.1.T6, 4.1.T9, 4.1.T7 and 4.1.T3 are still in place. There is a degradation of the patches, which does not require a recovery and / or recycling channel for the discharged compositions (Figure 5)

Claims

CLAIMS 1- Method for stimulating latex production, characterized in that it comprises a step of applying a progressive release composition comprising a biocompatible and biodegradable copolyester capable of being obtained by the polycondensation of at least one dicarboxylic acid monomer and a polyol monomer, and a latex production stimulant, below the bleeding notch on a previously "scraped" area of ​​the trunk. 2- Method according to the preceding claim in which the polyol monomer is a triol, preferably glycerol. 3- Process according to any one of the preceding claims in which the dicarboxylic acid monomer is a dicarboxylic acid chosen from saturated aliphatic dicarboxylic acids and unsaturated aliphatic dicarboxylic acids, comprising 3 to 36 carbon atoms. 4- Process according to any one of the preceding claims in which the dicarboxylic acid monomer is a dicarboxylic acid is an aliphatic dicarboxylic acid corresponding to the formula [HOOC-(CH2)n-COOH], in which n is a number ranging from 1 to 20, preferably a number ranging from 1 to 10. 5- Process according to any one of the preceding claims in which the dicarboxylic acid monomer is chosen from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or a mixture of two or more of these dicarboxylic acids. 6- Method according to any one of the preceding claims in which the biocompatible and biodegradable copolyester is poly(glycerol sebacate) (PGS), poly(glycerol adipate) (PGA) or poly(glycerol sebacate adipate) (PGSA). 7- Method according to any one of the preceding claims in which the biocompatible and biodegradable copolyester is biosourced. 8- Method according to any one of the preceding claims in which the biocompatible and biodegradable copolyester has a number average molar mass of 800 g / mol to 3000 g / mol, preferably of 800 g / mol to 2800 g / mol, more preferably of 1000 g / mol to 2000 g / mol. Tl 9- A method according to any one of the preceding claims, in which the latex production stimulant is Ethephon. 10- Method according to any one of the preceding claims in which the content of biocompatible and biodegradable copolyester in the composition is within a range from 20% by mass to 90% by mass of the total mass of the composition. 11- Method according to any one of the preceding claims in which the stimulant content in the composition is within a range from 2% by mass to 10% by mass of the total mass of the composition. 12- Method according to any one of the preceding claims in which the composition comprises water in a content within a range from 1% to 30% by weight, preferably from 2% to 20% by weight, particularly preferably 5% to 15% by weight of water. 13- Method according to any one of the preceding claims comprising a vegetable filler, preferably a wood flour, in a content within a range from 5% to 40% by weight, preferably from 8% to 30% by weight, relative to the total weight of the composition. 14- Method according to any one of the preceding claims in which the composition is applied in the form of a preformed and / or pre-cut patch. 15- Method according to any one of the preceding claims in which the composition is applied to a previously "scraped" area of ​​the trunk located 4 cm to 20 cm, preferably 5 cm to 15 cm below the bleeding notch.

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