BR102021025728A2 - GLYCEROL POLYMER BASED GLASSES - Google Patents

Abstract

The present invention consists in the application of encapsulators of glycerol polymers, obtained by polycondensation reaction through the combination of glycerol with other monomers such as short and long chain diacids and anhydrides for controlled release of agricultural inputs, not limited to, but preferably, fertilizers , micro and macronutrients, pesticides and herbicides. As well as, one in order to add final value to glycerol for use in agriculture.

Description

GLYCEROL POLYMER BASED GLASSES

[001] The present invention deals with an application of controlled release systems of agricultural inputs based on glycerol polymers consisting of polyesters obtained by polycondensation reaction of glycerol through the combination of monomers, such as diacids/anhydrides, of short chains and /or long for controlled release of agricultural inputs, not limited to, but preferably, fertilizers, nutrients, pesticides and herbicides.

[002] With the use of polymers derived from glycerol with varying concentrations of fertilizers, nutrients, pesticides and herbicides, different release profiles are produced. Furthermore, the choice of the type of monomer (diacid or anhydride) used with glycerol results in polymers with different degrees of hydrophilicity and release profiles, which can be adjusted according to the needs of a given type of culture.

[003] A particularity of the product is the use of biodegradable polymers that act in the balance of microorganisms and/or decomposers of organic matter present in the soil and in the encapsulation of fertilizers, compared to conventional techniques that deposit fertilizers directly to the soil, generating significant losses due to volatilization and leaching processes.

[004] Another specificity of the product is the possibility of controlling the availability of the input accessible to the plant through the content and choice of encapsulation form of the inputs such as disks, particles or powder of controlled granulometry.

[005] The polymers used in the development of these encapsulators are produced through polycondensation of monomers. Glycerol polymers were synthesized maintaining the 1:1 stoichiometric ratio of [OH]:[COOH] groups. They are: poly(glycerol adipate),PGA; poly(glycerol citrate),PGC; poly(glycerol succinate),PGSu; poly(glycerol adipate-co-succinate)PGASu.

[006] In the synthesis of polymers/copolymers of glycerol, the stoichiometric ratio of 1:1 of the groups was maintained. Proportional values for each reagent were determined and weighed. The reagents were mixed in a glass reactor, adding a bubble/reflux condenser, thermometer, inert gas, under stirring at a temperature ranging from 120 to 150°C, without the use of catalysts. The calculation of the Acid Number (NA) for monitoring the reaction was carried out using Carothers' equations, where the critical polymerization extension value for polymers (Pc) and the average functionality of the polymer obtained (fav) are highlighted in Eq.1 (Figure 1) and in Eq.2 (Figure 2).

[007] Monitoring by titration, using an automatic burette with a solution of potassium hydroxide (KOH) at a concentration of 0.11 g/mL, that is, the amount of KOH in milligrams required to neutralize one gram of unreacted acid . During synthesis, polymer samples were taken to monitor the course of the reaction. Samples of 2-3 mg polymers were weighed and solubilized in 5mL of solution of (Toluene (50%), isopropyl alcohol (25%) and methyl ethyl ketone (25%). the mass of solubilized polymer and the volume of KOH added and its concentration Eq.3 (Figure 3) Where Pc is the critical polymerization extension value, ʄav is the average functionality, NA the acid number, n is the number of moles, C concentration, V volume, M molar mass.

[008] Patent BR 102017020830-3 A2 describes a manufacturing process and fertilizer composition with encapsulated nitrogen for controlled release of nutrients into the soil. It comprises a manufacturing process for a fertilizer with nitrogen encapsulated in a starch molecular structure with the aim of slowly releasing nutrients into the soil, causing the plants to absorb all available nitrogen with minimal loss, making the nitrogen more stable and with slow and controlled release.

[009] The US5679129 patent describes a composition with slow release fertilizer or pesticide. The composition is made by combining thermoplastic resin with cellulosic material and then adding a fertilizer or pesticide. The thermoplastic resin and cellulosic material preferably come from the solid waste stream. The resulting composition can be molded into various shapes and/or ground into a granular powder.

[010] Patent BR1020150164548 A2 deals with a development of controlled release systems of fertilizers of the NPK type (5 and 10% by mass) and incorporated into modified bentonite nanoparticles (m-Bent) (15 and 30% by mass). Using poly(hydroxybutyrate) (PHB) as matrix, through melt processing. In addition to releasing in solution, the systems show degradation in soil with a decrease of up to 77% of their mass in 90 days, gradually releasing the components as the polymer breaks down.

[011] The patent PI0900962-0 A2, refers to biodegradable polymeric blends and controlled release process. Blends comprising isolated soy protein and a biodegradable polyester, the active ingredient (drugs or agrochemicals), plasticizer and water were prepared. In this case, the polymeric blend containing the active ingredient comes into contact with the place where it should be released. The blends showed an immiscible morphology, in which the isolated soy protein matrix present in greater quantity was presented as the continuous phase and the PLA as the dispersed phase in the matrix. In these blends, the NPK is dispersed in the polymer. In the controlled release studies, the analyzed blends showed a delay of approximately eight times compared to the free nutrient release (without encapsulation).

[012] Patent CN201210497247 cites controlled release systems for inputs and insect prevention. It is composed of sulfur-coated urea and 5% recycled thermoplastic resin. The mixture is made dry, with actinomycete bacteria, neurosporaepenicillium bacteria and bentonite. The invention further provides a method of preparing and applying the fertilizer for planting flowers. It also provides simultaneous prevention against soil-borne and insect-borne diseases, prolonging fertilizer efficiency.

[013] Patent Pl9906487-1 formulates a slow/controlled release fertilizer formed from nutrient granules that have pre-coating layers of organic oil, such as linseed oil, before applying an encapsulating polymeric cover. The precoat may also contain a binding agent, such as fine clay, and a drier. The use of the precoat provides a controlled release of the inserted nutrient.

[014] One of the advantages of using these encapsulators compared to conventional fertilizers are the lower frequency of applications, reduction of loss of nutrients by leaching, immobilization and volatilization, elimination of damage caused to roots by the high concentration of salts, greater practicality in the handling thus reducing labor for topdressing fertilization, less contamination of groundwater as well as surface water. In addition to adding value to a biodiesel by-product, the supply of the nutrient inserted in these controlled release systems will be almost constant, meeting the plant's demand.

[015] The main objective of the present invention is to develop encapsulating systems from glycerol with di and tri functional acids and/or anhydrides by polycondensation reaction used for controlled release of agricultural inputs.

[016] The use of these systems not only adds value to glycerol, a by-product of biodiesel, but is also an alternative for its use on a large scale, as well as avoiding loss of nutrients by volatilization and leaching.

[017] The invention can be better understood through the following description, in line with the attached figures.

[018] FIGURES 1, 2 and 3 present example equations.

[019] FIGURE 4 shows the graphs of mass loss of pure polymers/copolymers and with 20% NPK of the biodegradation test in simulated soil in times from 0 to 120 days: (a) PGA, (b) PGSu, (c) ) PGC, and (d) PGASu.

[020] FIGURE 5 shows the visual aspects of lettuce plants (in triplicate) comparing 2 planting cycles, in response to the application of treatments without and with polymeric matrices: (a) NPK only, (b) PGA+NPK, (c) PGC+NPK, (d) PGSu+NPK, (e) PGASu+NPK and the (f) control.

[021] With reference to FIGURE 4, it can be seen that the glycerol polymers/copolymers underwent weight loss changes in the times tested. Color changes, cracks and fragmentation of the samples were also observed, characteristics seen in the biodegradation of polymers.

[022] The average values found for weight loss after 30 days of testing are approximately 15% for pure polymers/copolymers and 27% for samples containing NPK. In the second weighing after 60 days, the average results of the samples without fertilizer were 28.9% followed by 42.9% for those containing the agricultural nutrient. For the times of 90 and 120 days, the results followed the same trend, revealing considerable mass losses. With values reaching 51.8 and 74% for pure samples and 60.9 and 77% for polymers/copolymers with NPK, respectively.

[023] This biodegradation process is due to the action of microorganisms and/or decomposers of organic matter present in the simulated soil, in which they act by breaking the polymeric chains, starting to be processed and metabolized, thus releasing CO2, H2O and nutrients. This whole process occurs naturally, being responsible for breaking the primary bonds of the main chain, influencing changes in physical, chemical and biological properties. It is worth noting that the presence of NPK fertilizer in the polymeric samples made the mass loss greater at all times tested. All analyzes showed that glycerol polymers and/or copolymers are biodegradable, a very important property for agricultural applications.

[024] With reference to FIGURE 5, one can observe the visual aspects of lettuce plants in the 1st and 2nd cycle in response to the application of treatments: Only NPK, (PGC, PGA, PGSu and PGASu) +20%NPK and the control (only soil nutrients), on differences in size and quantity of leaves, fresh mass of shoots and diameter of stems. The treatments that stood out with the best results in all aspects were: Only NPK (conventional treatment), an expected result since there is no physical barrier that would prevent the nutrients from being absorbed immediately, and the PGC treatment, which is characterized by having hydrophilic character and, consequently, be a faster release system, compared to other treatments. Treatment with PGC+20%NPK makes nutrients available to the root system of plants more quickly, resulting in plants with sizes and numbers of leaves greater than other plants with other types of treatments such as PGA, PGSu and PGASu, which contain a more hydrophobic character and, therefore, a slower release of nutrients compared to PGC.

[025] For the experiment of the 2nd cycle, the new seedlings were replanted in the same pots of the 1st cycle, without nutritional replacement in any pot, in order to verify if there was still release of fertilizers in the soil.

[026] For the 1st and 2nd cycles, the total time of the experiments was 65 days including planting and replanting of seedlings.

[027] In the 2nd cycle, the plants showed delayed growth, when compared to plants in the 1st cycle, showing a reduction in growth, in the number of leaves and in the size of the stems. It is worth noting that one of the samples from the reference treatment (control) had mortality, all these deficiencies were attributed to the absence of an adequate amount of nutrients available in the soil. The best results in all visual aspects in the 2nd cycle were the treatments that have a slower controlled release, in this case, PGA, PGASu and PGSu, this type of release made the nutrients stay longer in the polymeric matrix and only later were they released in a more controlled manner to the plants.

Claims (7)

“Encapsulators of agricultural inputs based on glycerol polymers” characterized by polycondensation of glycerol with diacids and/or anhydrides with the addition of agricultural micro or macronutrients, in mass proportions, not limited but preferably between 0.01% and 50%. "Encapsulators of agricultural inputs based on glycerol polymers", according to claim 1, characterized by the use of biodegradable polymers in the application of controlled release systems of agricultural inputs, using glycerol, preferably as a by-product of biodiesel. "Encapsulators of agricultural inputs based on glycerol polymers", according to claims 1 and 2, characterized by the use not limited to, but preferably of adipic, citric and succinic acids and the polymers poly(glycerol adipate),PGA; poly(glycerol citrate),PGC; poly(glycerol succinate),PGSu; poly(glycerol adipatoco-succinate),PGASu. "Encapsulators of agricultural inputs based on glycerol polymers", according to claims 1, 2 and 3, characterized by allowing the release of inputs according to the chain size, flexibility/rigidity and controlled hydrophobicity/hydrophilicity, thus resulting in deliberation systems capable of being adapted to a certain type of culture. "Encapsulators of agricultural inputs based on glycerol polymers", according to claims 1 to 4, characterized in that the inputs are covered by polymeric material obtained by the polycondensation of glycerol with the function of controlling its release, not limited to, but preferably, fertilizers, micro and macronutrients, pesticides and herbicides, herein referred to as agricultural inputs. "Encapsulators of agricultural inputs based on glycerol polymers", according to claims 1 to 5, characterized in that they can be used for any type of crop, such as: forestry, coffee, horticulture, citrus and fruit in general, sugarcane -sugar, floriculture, grass, landscaping, hydroseeding, production and transport of seedlings, protection of bare roots, floral decoration, among many others in soil fertilization, as in the prevention against diseases transmitted by insects and/or pests, simultaneously prolonging the efficiency of the encapsulated input. "Encapsulators of agricultural inputs based on glycerol polymers", according to claims 1 to 6, characterized in that they can be applied in all types of soil, whether clayey, sandy or humus, including the possibility of being used in aqueous media for crops hydroponics.

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