BRPI0904733A2 - superabsorbent polymer for use in agriculture consisting of a mixture of super-porous cross-linked starch and polyvinyl alcohol and method of preparation - Google Patents

Abstract

SUPERABSORVENT POLYMER FOR USE IN AGRICULTURE CONSTITUTED WITH A MIXTURE OF STARCH AND POLY (AI1COOL VINHAÇO) RETICULATED AND SUPERPOROUS AND PREPARATION METHOD aims at obtaining a polymeric matrix composed of starch of very rapid biodegradation (about one or two weeks in any type of soil ), mixed and eventually reticulated, by physical or chemical means, to POLI (ALCOOL VINILICO) (PVA) of slower biodegradation (in a few months and depending on the presence of specific microorganisms). Starch is in the form of particles of spheroidal geometry. super-expanded dispersed in the PVA matrix. The polymeric matrix of the present invention increases, by absorbing water, by more than 400 times its initial mass; consequently, the degree of soil hydration also increases, making water available gradually according to the plant's needs. Once biodegradable, it allows microorganisms present in the soil to consume its molecules, providing, over time, an even more fertile soil for the environment. The polymeric matrix of the present invention can be prepared by extrusion and thermoforming, among other techniques used in the plastics industry.

Description

"SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSISTENT OF A MIXTURE OF SUPERPRODUCTIVE RECTIFIED STARCH AND POLY (VINYL ALCOHOL) AND PREPARATION METHOD"

Field of the Invention

The invention, which is pending patent, is intended to obtain a polymeric matrix composed of very rapid biodegradation starch (about one or two weeks in any type of desolation), mixed and, if necessary, physically or chemically cross-linked to POLY (VINYL ALCOHOL) (PVA). non-miscible slow-moving degradation (in a few months, depending on the presence of specific microorganisms). Starch is in the form of approximately super-expanded spheroidal particles dispersed in the PVA matrix and should have as high porosity as possible to allow extremely rapid water uptake (400% in 5 to 10 min.), Biodegradable for application to target soils. to agriculture. The highly porous product increases by liquid absorption by more than 400 times its initial mass and consequently increases the degree of hydration of the soil by providing water (along with efferentant nutrient, where appropriate) in a gradual manner according to plant needs.

The product object of this patent application has, applied as a soil treatment for agriculture the following additional original properties:

• Increased porosity and increased water absorption kinetics and the amount of water retained per unit mass as a function of application time;

• Controlled release of water according to the needs of the specific crop planted (prolonged and controlled irrigation);

• Precise modulation of the release of active agents of interest to agriculture (nutrients and fertilizers) Biodegradability allows microorganisms present in the soil to consume their molecules, thus enabling soil fertilization over time.

The attainment of high porosity is preferably achieved by foaming processes, but other processes known to those skilled in the art may be used with equivalent results, such as lyophilization. The foaming process is performed by using chemical and / or physical blowing agents taken and processed through extrusion, thermoforming, among other techniques used in the plastics industry.

Motivation For The Studies That Resulted In The Invention

From water everything comes! All activities are dependent on this precious element: industry, electricity, civil construction, agriculture, among many others, leaving the most important purpose of human and animal consumption undone.

Unsustainable agriculture is a threat to water resources, causing siltation of waterways, pesticide contamination among many other negative environmental impacts.

The rural sector worldwide consumes most of the available water. Irrigation accounts for most of this consumption. Advances in biotechnology and demand from international markets have contributed, in recent decades, to the exponential growth of arable land in Brazil.

Usually these areas are irrigated through water from rivers and lakes, with the evident depletion of their capacities.

Some parts of the planet suffer from water scarcity, making such "dead" points lifeless, without agricultural production, without utility. In these desert and semi-desert regions, such as the arid and semi-arid Northeast Brazil, water becomes even more precious and should, when available, be used rationally and economically.

On the other hand, in more developed regions, it is observed that water is becoming increasingly scarce either by quantity or, if not, by its quality. Thus, the usorational must also be observed in these places systematically. Water pollution has been a major concern not only of environmentalists, but of society as a whole.

Thus, rational water management is a measure which imposes that the product now pending for the patent meets this pressing need.

The necessary elements for the development of the plants: water and nutrients come from the soil and, for that, the correct treatment and the adequacy of the soil unconditionally promote the efficiency of the crops with the increase of the production and the quality.

Equally impacting on the environment is soil erosion due to excess water absorbed by the soil.

Thus, considering the needs of rationalization of water use and soil adequacy, we conclude the need to make available a product that has the following applications:

• Water retention, with consequent increase of soil moisture for agriculture;

• Water retention, to inhibit soil erosion;

• Continuous supply of water to crops

• Increased plant resistance during periods of absence or water scarcity (scheduled irrigation);

· Decreased plant temperature in dry areas;

• Reduction of irrigation costs with the rationalization of water use;

• Increased agricultural productivity • Increased water retention as a function of use time until biodegradation proceeds in a major way.

• Total biodegradation and absence of toxic waste in case of fires or burned.

Foundations of the Invention

Starch And Pva

Considering the purpose of the product object of the present patent application, the fundamental assumption of being such a biodegradable product and not aggressive to the medium that will be applied to the plants that will be absorbing water and / or the products encapsulated therein. Therefore, the product must be: Biodegradable and intermediate by-products of biodegradation must be nontoxic or not bioaccumulate.

Existing superabsorbents are, for the most part, produced from synthetic petroleum-based base monomers. Such synthetic monomers are almost always extremely toxic, but after polymerization can form totally non-toxic products. The problem lies in the degradation steps that a product of this nature goes through in the soil. Fragmentation of polymeric molecules in degrading processes can always generate monomers or oligomers of excessive toxicity and be absorbed by plants with subsequent human consumption.

In order to replace superabsorbent products made from synthetic, toxic and non-biodegradable polymers, superporous matrices based on mixtures of non-aggressive (toxic) biodegradable and synthetic polymers, such as starch or starch foams (US 6,146,573, US 5,545,450, US 4,863,655, EP 0712883 A1, US 3,949,145) encapsulated by PVA (Progress in Polymer Science, Volume 28, 6, June 2003, Pages 963-1014).

It is noteworthy that starch and starch are synonyms, however, in Brazil, it is commonly called starch the starchy substance obtained from vegetables and / or oilseeds such as: corn, rice, wheat etc. and starch, obtained from root roots such as cassava, character, potato etc.

Starch, however, has low resistance to water, oil and fat, and its aging (retrogradation). Variations in mechanical properties under moisture limit the use of this product's foamed products. Another limiting factor in the use of these foams is the difficulty in processing starch and starch by extrusion. Thermoplastic Starch (TPS, "ThermoplasticStarch") is produced by plasticizing starch in the presence of a plasticizer (water, glycerin, sorbitol, etc.) at high temperatures (90 to 190 ° C).

The shear of the product is obtained by extruding the material and other forms of shear exist.

The chemical nature of the starch and the amount of plasticizer, as well as the temperature required to plasticize it in the extruder, has an important influence on the properties of the formed TPS.

To improve the processability of starch and nuisance starch, many authors suggest (a) Addition of water: [mixture of starch and plasticizer (US 7,384,993, US5,569,692)]. Whereas the extrusion process requires high pressure and the mere aggregation of water at ambient temperature does not produce the necessary pressure, it is necessary to process the product at a temperature between 120 ° C and 170 ° C and ( (b) Addition of additives: such as dimethyl sulphoxide, for example to reduce the melting point of starch (US 5,362,777).

In PI 0205056-0 the inventors suggest incorporating fiber into the TPS in the starch and water mixture to improve mechanical properties; the gas permeability and especially the water resistance of the mixture. However, fiber addition is limited due to the dispersion difficulties of the mixture. The incorporation of synthetic polymers (US 6.14 6.573) and the addition of modified starch conditions (US 5.314.754, US 5.316.57.8, US5.869.647) promote improved starch resistance to water.

Controlled Release of Water, Pharmaceutical Assets and

Agrochemicals

The first attempts to control the release of a chemical active were made when coating pills to mask the unpleasant taste of the drugs.

In the 1940s the first controlled deliberation systems emerged where pharmaceutical products were introduced that release part of the drug in the stomach and part in the gut. Such medications were sensitive to physiological variables.

In 1952 came the drug called Spansule®, from the company Smithkline Beecham. The compound consisted of a hard gelatin capsule containing spherical granules corresponding to different coatings. Using coatings of different thicknesses, the periods for their dissolution varied, prolonging the action of the therapeutic agent. These coatings allowed the initial release of the required therapeutic dose, followed by decreasing release over a period of 10-12 hours. However, the release of these products depends on the external environment that would greatly vary between patients and the external environment. Since they were in the 1960s, many efforts have been made to develop products capable of deliberating drugs by predictable kinetics. Thus, such products are not significantly affected by the external environment or characteristics of each patient. Several techniques have been developed and applied to promote controlled drug release, in order to regulate their release rate, maintain their therapeutic level for a longer period of time (known process as zero-order release), and direct their action to a tissue. specific. (Biomaterials Science: an introduction to biomaterials in medicine, Buddy Ratner, 2004, Elsevier)

The same concepts applied to the release of pharmaceutical assets, as described above, are valid for the release of agricultural assets, whether to promote plant health, to increase production or to benefit the environment.

Thus, encapsulated natural products such as amino acids, brassinolides (growth promoter) and intensively contanol (growth regulator) can be encapsulated for controlled release, with highly positive results, as such ingredients will be released according to the need for the plant and in due time.

The inclusion of PVA in the formulation has the condition of retarding starch biodegradation. Such control takes place according to the amount of PVA added and the degree of cross-linking, as attested in their detailed study by Emo Chiellini and co-workers in "Biodegradation of Poly (Vinyl Alcohol) Based Materials" (Progress in Polymer Science Volume 28, issue 6, June 2003, Pages 963-1014).

There are numerous qualities of super-porous and superabsorbent polymer matrices based on products obtained from foam processes (or porosity generation processes), including:

• The ability of the porous product to retain and release water to the roots of the plant as needed, so as to promote vigorous and optimal growth;

• the porous product can remain effective and even increase its water absorption for the period from application (in the soil) until harvesting, being able to repeat the hydration cycle several times, and may be more hydrate and store water whenever moisture enters the soil. permanently ensuring a moist soil, which is conducive to good plant productivity. It is also desirable that porous products are produced from renewable sources such as starch rather than petroleum based, since these latter polymers are generally toxic. In the case of synthetic superabsorbents, they have the characteristic of absorbing the liquid without releasing it. Thus, the water that should be destined for the plants remains in the product, to the detriment of what is necessary for the plants. This feature is very effective for many products, such as disposable diapers and tampons, but certainly not for plants, as water must be available to the roots.

The product of the present invention is more efficient than those made from polyacrylamide, sodium epoliacrylate as the kinetics of water and / or other ingredients retention and modulation can be modulated by varying the ratio of natural polymer and synthetic polymer (% deformulation), while still offering the following advantages:

1.Toxic, unlike polyacrylamide, polyacrylonitrile etc, even when burned or incinerated;

2. Biodegradable, pH neutral and safe to use for all crops;

3. Resistant to various cycles of use; Adaptable to multiple crops that have a very varied production cycle (two weeks to months) with different water needs;

There is no similar product offered to the market or patented that meets such requirements and properties.

Summary of the Invention

Considering all the above elements, notably the formulation of a product whose main characteristics are: i) biodegradation; ii) non-toxicity and iii) swelling rate, a product has been developed which:

1. The absence of toxicity relates to the selection of suitable base polymers. Starch and PVA were elected. Both naturally degrade without leaving toxic residues. The majority use of starch is surprising because it has amphoteric characteristics, because although hydrophilic it is relatively hydrophobic;

2. Biodegradability: Starch is rapidly degraded, but by aggregating PVA that has the property of micro-encapsulation, retarding the biodegradability of the product;

3. Resistance to various cycles of use is related to the increased resistance of the porous product to water and its ability to remain intact for the period from its application to the soil until harvest by incorporating cross-linking agents into the mixture of the foamed product. starch and synthetic polymers;

4. Adaptation to multiple cultures with varying cycles correlates with the porosity of the foamed product. The invention is based on the discovery that porosity and permeability of porous matrices can be affected by the composition of the formulation. It has been shown in accordance with the present invention that the viscosity of the mixture is a prime factor for the pore size of the obtained foams. Mixtures with low amounts of water in their composition and consequently low flowability once expanded do not form sufficiently porous foam structures to gradually absorb and release water and are not able to store more than 100 times the mass itself in water. Increasing viscosity makes it difficult to homogenize the foam by promoting bubble breakdown and, consequently, decreasing the porosity of the foamed product of the present invention. Waterborne formulations (greater than 25%) have low viscosity and therefore, upon expansion, are very porous. This decrease in the viscosity of the mixture facilitates the deformation and growth action of the bubbles that originate the pores. Porous superabsorbents, or fragmented foams produced with low viscosity formulations, are capable of storing water more than 400 times their own mass in water.

A further advantage of the present invention is that agranulometry and uniformly sized pores are capable of expanding and contracting, decreasing soil compaction to improve aeration of the plant root system.

The invention relates to a porous matrix obtained by a foaming process obtained basically from PVA mixed starch, water and crosslinker which has the property of absorbing water and releasing it to the roots of the plant as needed in order to promote plant growth. vigorous, with great yields. Such propriety is important, as it allows to keep the soil moist, conducive to the good health of the plants. This blend provides a much broader effect than each of the polymers alone. Upon contact with water, they rapidly absorb H2O molecules to form a gelatinous substance capable of storing more than 400 times their own mass in water.

The superabsorbent porous products of the present invention are obtained by mixing water, ePVA starch, crosslinker added and heat processed.

Because they are composed of starchy PVA, the foam products are biodegradable and non-toxic. Starch comes from a renewable source and is available all year round.

Additives are used in the present invention depending on the desired foam product characteristics, providing results in increasing foam porosity and other active additives for the purpose of gradually releasing water, fertilizers, amino acids and decreasing agents as commonly used. in the farming.

For the production of starch / PVA foamed products, the mixture (starch, PVA, water, crosslinker and additives) must have a moisture content between 25% and 99% relative to the starch mass, depending on the equipment and process used, additive ( plasticizers, thickeners) pure or diluted 0.005% to 70% in water and crosslinking agents (0.001% to 10%). The mixture may be added with organic, inorganic fillers and coloring pigments in concentrations ranging up to 20%. The mixture may be processed, for example, by means of thermoexpansion, extrusion and thermo-pressing.

Description Of Invention Embodiments

The present invention relates to a porous polymeric matrix of different particle sizes produced by a process of. starch foaming in which a suitable formulation composed primarily of water, starch mixed with the PVA and crosslinker is expanded at high temperature to produce porous foams and then ground.

It has been shown in accordance with the present invention that the viscosity of the mixture is a prime factor for foam aporosity and its ability to gradually absorb and release liquids into the soil.

Optional adjuvants may be added to the formulation of the inventive foam, such as plasticizers, thickeners, inorganic and inorganic fillers and pigments to increase the foam resistance to water and other active ingredients, such as: controlled release of fertilizers, amino acids and growth agents.

In the present invention, the fully biodegradable and / or compostable foamed product comprises: a) 50% to 90% by mass of starch; b) 0.005% to 70% additives (preferably 2% to 10% polyol family plasticizer and 10% to 40% water-soluble polymer as PVA and copolymers); c) 0.001% to 10% crosslinking agents (preferably from 1% to 5% sodium glutaraldehyde eborate) and d) 0 to 50% active (preferably from 0.01 to 10% fertilizers, amino acids and growth enhancers)

The mixture is prepared at room temperature and homogenized with the aid of a conventional mixer. It is recommended to heat the mixture of starch, water and additive to a temperature of 130 ° C to 200 ° C for 1 hour in an oven before adding the active agent. . This makes it possible to improve the compatibility between the materials (starch, water and additives) and the stabilization of the foamed product against humidity.

The mixture is then processed in an extruder or thermoforming at a temperature ranging from 30 ° C to 220 ° C, depending on the type of starch and additives added. After processing, the foamed material of the present invention is cooled and then ground to a temperature which may vary from -190 ° C (with the aid of liquid nitrogen) to 130 ° C, depending on the material to be processed and the process used. It is recommended to dry the then decayed foamed product (5-30 mesh) at a temperature of 60 to 250 ° C, depending on the actives, additives and crosslinking agents used in the preparation of the product.

The actives and additives may be incorporated into the mixture, pure or dissolved, in concentrations for the 0% to 50% by weight active ingredients (preferably 0.01% to 10%) and for the 0.005% to 70% additives additives ( preferably from 2% to 10% of plasticizer of the polyol family and from 10% to 40% of a water soluble polymer such as PVA and PVAc) in a suitable solvent.

This document uses the term foam porosity as equivalent to granular porosity. Foam porosity is expressed as a percentage and is defined as the pore volume divided by the total volume of a foam sample. The pore volume corresponds to the approximate void volume of a foam, so it is equivalent to the apparent density of the foam, multiplied by the density. Given that the density of these materials is close to the unit, the density values in module can be considered to correspond to the values of porosity in modulus. Foam obtained prior to comminution in fine particle size should have a density in the range of 20 to 500 kg / m3, but smaller foams are preferable since porosity is a function of density. It should be noted that densities in the 100kg / m3 range are easy to achieve with this process which is usually sufficient to generate superporous granulation after comminution, so the process beyond original is highly feasible.

Product Components

Natural and synthetic polymers - are used to increase the mechanical, thermal and barrier resistance of foamed products, comprising proteins, polysaccharides, polyesters, polyvinyl acetate, polyvinyl chloride, polyvinyl chloride, polyacrylate, hydroxyethyl. -methyl cellulose, polyurethane, poly (lactic acid), polyethylene, wax, latex, elastomer, gelatinized starch (preferably at concentrations of 3% to 20%), carboxymethyl cellulose, gum, gelatin, polyhydroxy alkanoates , caprolactone, polycaprolactone, poly (hydroxybutyrate), cellulosic polymers, starch, starch, chitosan, cellulose derivatives, lignin, cellulose fiber, natural fibers, polyvinyl pyrrolidone, resistant starch, regenerated cellulose, natural gums, polystyrene, poly (vinyl chloride) ), ABS, polypropylene, epoxy, among others.

Plasticizers - They are capable of improving the flexibility and processability of the foamed product of the present invention. water, alcohols, aldehydes, ketones, organic acids, amines, esters, amides, imides and polyols, such as ethylene glycol, propylene glycol, glycerine, propane-1,3-diol, butane-1,2-diol, butane- 1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,5-diol, hexane-1,6-diol, hexane-1,2,6-triol, hexane- 1,3,5-triol, xylitol, neopentylglycol, polyvinyl alcohol, polyethylene glycol, polyglycerol, sorbitol, mannitol, desorbitol ester, sorbitol acetate, sorbitol diacetate, sorbitol monoethoxylate, sorbitol dihexylate sorbitol dihexylate, sorbitol - sorbitol, trihydroxymethylaminomethane, glucose / PEG, trimethylolpropane monoethoxylate, mannitol monoacetate, mannitol monoethoxylate, butyl glycoside, glycose monoethoxylate, alpha-methyl glycoside, decarboxymethyl sorbitol sodium salt, linear adipates phthalate, sebates , n-octyl and n-decyl phthalates, butyloctylphthalate, epoxy, phosphates, chlorinated paraffins, butylbenzylphthalate, tricres phthalate, polyesters, phthalic acid and glycerin esters, trimethylates, polyesteresteroplastics, azelate, glutarate, succinate, polyvinyl acetate, polyvinyl alcohol, DMSO, mono ediglycerides, among others.

Lubricants - Improve the processing of the foamed product of the present invention. Silicones and fluorides, paraffin waxes, metal stearates, fatty acid esters, fatty acid amides, fatty acids, alcohols, among others, are commonly used.

Loads - Are capable of increasing mechanical strength such as: kaolin, mullite, talc, calcite, bentonite, mica, illite, alumina, dolomite, smectite, montmorillonite, chromite, cyiamite, feldspar, graphite, pyrophyllite, gypsum, zirconite, minerals, calcium carbonate, calcium sulfate, iron oxide, barium sulfate, organic phosphorus compounds, polyphenols, hydroquinones, diarylamines, thioethers, metal-aromatic carboxylates, dosorbitol derivatives, organic phosphates, talc, poly (vinyl cyclohexane), poly (3-methylbut-1-eno), silanols, release agents, metal salts, ground rocks, bauxite, granite, limestone, sandstone, clay, alumina, silica, glass microspheres, hollow glass spheres, porous ceramic spheres, soluble salts, magnesium carbonate, calcium hydroxide, rare earths (found in the form of the minerals monazite, bastnasite, xenothymia and loparite, and lateritic clays adsorbing ions), calcium aluminate, titanium dioxide ceramics, light expanded clay, zirconium compounds, zeolites, metal particles, ores, glass fibers, graphite, silica, ceramic and metal, cotton, wood fibers, sisal, hemp, bagasse, recycled paper fibers, fibers polymers, invert sugar and sucrose, among others.

Dyes - These include pigments and dyes, organic and inorganic, or mixtures thereof which may be added to the foamed product to improve appearance such as: smoke black, titanium dioxide, chlorophylls, carotenoids, flavonoids, betalains, tannins, quinone, xanthones, tartrazine, yellow twilight, red 40, vermilionhoponceau, bright blue, anthocyanins, lapachol, erythrosine, flower extracts (leek, cow's clove, azalea, among others), vegetable extract (bell pepper, cabbage, beet, among others), fruit extract (blackberry, jabuticaba, jambolão, grape, among others), annatto, beta-carotene, among others.

Cross-linking: promote cross-linking of starch and alter the ability of superabsorbent polymers to gradually retain and release water. They are: formic aldehyde, glutaric aldehyde, calcium benzoate, sodium borate, glutaraldehyde, among others. Mixture can also be subjected to the action of ionizing radiation from sources of different wavelengths (gamma or UV) or electron accelerators to promote areticulation of the mixture.

Fertilizers and amino acids - (some non-exhaustive examples): sodium nitrate (Chilean saltpeter), depotassium nitrate, ammonium sulfate, ammonium nitrate, decalcium sulfate, magnesium sulfate, urea, superphosphates and phosphites.

Growth Agents - Substances used to optimize seed twinning, fruit ripening, nutrient absorption, increased protein synthesis, increased immunity and plant resistance (eg chelate amino acids, brassinolides, triacontanol, algal extracts, among others). .

Practical Applications

EXAMPLE 1. The superabsorbent polymer was obtained from a mixture of 41% cassava starch (25% moisture), 38% polyvinyl alcohol polymer, 2% comoplastic glycerin and 1% sodium borate (crosslinker). . The mixture was processed in a twin screw extruder using its constant feed speed of 1.2 kg / h, four screw rotation speeds (100, 200, 300 and 400 rpm).

The temperature profiles were 40 ° C in zone 1 and 60,100, 120 and 140 ° C in zones 2, 3, 4 and 5. Then, the extruded and expanded foams were flaked and oven dried. at 80 ° C with air circulation for 3 hours, then obtaining various extruded flake granulometry of superabsorbent polymers. These flakes were kept for one week in plastic bags at room temperature to achieve a moisture balance between the flakes. The dried flakes were ground in a knife mill and separated into 10 mesh sieves. The degree of swelling (GI) of the superabsorbent polymer was determined at room temperature (25 ° C) by soaking the foamed product (2g) in 100mL of distilled water. The swelling degree of the foamed product was calculated by the relation between the dry sample weight (AS) and the wet sample weight (AI) from the equation: GI (%) = ((AI - AS) / AS) χ 100. The biodegradation test was performed in soils simulated, and may present the typical errors of this test, but for highly crosslinked polymers no main solubilization.

The results are presented in the table below:

<table> table see original document page 18 </column> </row> <table> The biodegradation test showed that after only two weeks, the superabsorbents with water had a swelling much higher than 2000%, reaching 4000 to 5000%, thus showing a growth capacity of swelling over time.

EXAMPLE 2. The superabsorbent foam product prepared according to Example 1 was compared for degradation purposes with the polyacrylonitrile and polyacrylamide superabsorbent polymers, both from the point of view of the biodegradability itself and the presence of toxic intermediates generated during the biodegradation process.

<table> table see original document page 19 </column> </row> <table>

The generation of high toxicity products can be observed as intermediates of the polycrylamide biodegradation process, and the same is expected for polyacrylamide grafted products.

EXAMPLE 3. The superabsorbent foamed polymer was obtained from two mixtures by varying the amount of water and consequently the viscosity of the solution. In one mixture 59% cornstarch, 29% depoli (vinyl alcohol), 10% water and 2% sodium borate were added. In the other, 68% cornstarch, 29% poly (alcohololvinyl). , 1% water and 2% sodium borate. The foams were obtained from the hot pressing (290 ° C) of the mixtures. After pressing, the foams produced were ground into knife mills, oven dried at 190 ° C for approximately 2 hours, and separated into 30 mesh sieves. The degree of swelling (GI) of the superabsorbent polymer was determined at room temperature (25 ° C) by soaking the foamed product (2g) in 100mL of distilled water. The calculation of the swelling degree of the foamed product was made by the relation between the dry sample weight (AS) and the swollen sample weight (AI) from the equation: GI (%) = ((AI - AS) / AS ) χ 100. The results are presented in the table below:

<table> table see original document page 20 </column> </row> <table>

As can be seen from the table above, increased viscosity hinders foam homogenization by promoting bubble collapse and, consequently, decreased porosity of the foamed product of the present invention. Formulations with high water content (over 25%) have low viscosity and, therefore, after expansion are very porous increasing the efficiency of the foamed product.

Claims (42)

1. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE STARK AND PVA CONSISTENT, characterized by a mixture of starch, PVA, additive processed in aqueous and heated solution for the generation of porosity by the formation of foams and further milling or granulation with the final obtaining of superabsorbent porous granules. 2. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED WITH ADHESIVE AND ADHESIVED PVA Starch, characterized in that the product has porosity (relative density) obtained in the range of 20 to 500 kg / m3. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE starch and PVA constituted according to claim 1, characterized in that the cross-linking agents are added: formic aldehyde or calcium aldehyde or calcium benzoate, sodium borate, glutaraldehyde. Or by subjecting the mixture to the action of ionizing radiation from sources of different wavelengths (gamma or UV) or electron accelerators. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE starch and PVA constituted according to claim 1, characterized in that additives for plasticizing function such as (individually or a mixture thereof) are added: water, alcohols, aldehydes, ketones, organic acids, amines, esters, amides, imides and polyols such as ethylene glycol, propylene glycol, glycerine, propane-1,3-diol, butane-1,2-diol, butane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,5-diol, hexane-1,6-diol, hexane-1,2,6-triol, hexane-1,3,5-triol, xylitol, neopentyl glycol, polyvinyl alcohol , polyethylene glycol, polyglycerol, sorbitol, mannitol, sorbitol ester, sorbitol acetate, desorbitol diacetate, sorbitol monoethoxylate, sorbitol diethoxylate, carboxymethyl sorbitol sodium salt, adipates, sebacates, linear phthalates, long-chain and phthalates, n-decyl phthalates, butyloctylphthalate, epoxy, phosphates, chlorinated paraffins, sorbitol hexaethoxylate, dipropoxylate sorbitol, amino sorbitol, trihydroxymethylaminomethane, glucose / PEG, trimethylolpropane monoethoxylate, mannitol monoacetate, mannitol monoethoxylate, butyl glycoside, glucose monoethoxylate, alpha-methyl glycoside, butylbenzylphthalate, polyestersylphthate, trichreside phthaterate, trimethylates, polyester ester plastics, azelate, glutarate, succinate, poly (vinyl acetate), poly (vinyl alcohol), DMSO, mono ediglycerides, among others. 5. SUPERSABLE SUMMER POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE STARCH AND ADDITIVE PVA according to claim 1, characterized in that lubricant additives such as: silicones and fluorides, paraffin waxes, metal stearates, acid fatty acid esters, amide acid esters are added. fatty acids, fatty acids, alcohols, among others. 6. SUPERSABLE SUMMER POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE starch and PVA according to claim 1, characterized in that additives are added with the function of increasing the mechanical strength of the foamed products such as kaolin, mullite, talc, calcite, bentonite, mica, illite, alumina, dolomite, smectite, montmorillonite, chromite, cyiamite, feldspar, graphite, pyrophyllite, gypsum, zirconite, minerals, calcium carbonate, calcium sulfate, iron oxide, barium sulfate, organic phosphorus compounds, polyphenols, hydrocjuinones, diarylamines, thioethers, nucleating agents (metal carboxylatesaromatics, sorbitol derivatives, phosphatesorganics, talc, poly (vinyl cyclohexane), poly (3-methylbut-1-ene), silanols, release agents, metal salts, rocksraoids, bauxite, granite, limestone, sandstone, clay, alumina, silica, glass microspheres, hollow glass spheres, porous ceramic spheres, insoluble salts, magnesium carbonate, calcium hydroxide, rare earths (found under the form of monazite, bastnasite, xenothymia and loparite minerals, and lateritic ions adsorbing), calcium aluminate, titanium dioxide, ceramics, light expanded clay, zirconium compounds, zeolites, metallic particles , ores, glass fibers, graphite, silica, ceramic and metal, cotton, wood fibers, sisal, hemp, bagasse, recycled paper fibers, polymer fibers, invert sugar and sucrose, among others. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTRUCTED AND ADDITIVE STARCH AND PVA CONTENT according to claim 1, characterized in that additives are added which increase the mechanical, thermal and barrier strengths of foamed products: proteins, polysaccharides, polyesters, poly (acetate (vinyl chloride), poly (vinyl chloride), polyacrylate, hydroxyethyl methyl cellulose, polyurethane, poly (lactic acid), polyethylene, wax, latex, elastomer, gelatinized starch, carboxymethyl cellulose , gum, gelatin, polyhydroxy alkanoates, caprolactone, polycaprolactone, poly (hydroxybutyrate), cellulosic polymers, starch, starch, chitosan, cellulose derivatives, lignin, cellulose fiber, natural fibers, polyvinyl pyrrolidone, resistant starch, regenerated cellulose , natural gums, polystyrene, polyvinyl chloride, ABS, polypropylene, epoxy, among others. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE STARK AND PVA CONSTITUENTS according to claim 1, characterized in that additives are added for the purpose of improving the appearance of the foamed product: carbon black, titanium dioxide, chlorophylls, carotenoids, flavonoids , betalaines, tannins, quinones and xanthones, tartrazine, twilight yellow, red 40, vermelhoponceau, bright blue, anthocyanins, lapachol, erythrosine, flower extracts (lentil, cow's clove, azalea, entreother), vegetable extract (bell pepper , cabbage, beet, among others), fruit extract (blackberry, jabuticaba, jambolão, grape, among others), annatto, beta-carotene, among others. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED RETICULATED STARCH AND ADHESIVES according to claim 1, characterized in that the mixture contains 25% to 50% moisture in the formulation relative to the solids mass. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED RETICULATED STARCH AND ADDITIVE starch according to claim 1, characterized in that the mixture contains 51% to 75% moisture in the formulation relative to the solids mass. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED RETICULATED STARCH AND ADDITIVE starch according to claim 1, characterized in that the mixture contains 76% to 99% moisture in the formulation relative to the solids mass. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED ADHYDRATED AND ADDITIVE STARCH AND PVA, according to claim 1, characterized in that the use of amidogelatinized in the composition of the mixture. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED RETICULATED STARCH AND PVA ADDITIVE according to claim 1, characterized in that the use of amidogelatinized in water at concentrations of 3% to 20%. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED OF ADHESIVED AND ADDITIVE STARCH AND PVA, according to claim 1, characterized by the use of cassava starch. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED WITH ADHESIVE AND ADDITIVE STARCH AND PVA, according to claim 1, characterized by the use of starch, flour and food. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE starch and PVA composition according to claim 1, characterized by the use of maize starch, potato starch, rice starch, cassava starch, amaranth flour, starch resistant, wheat starch, pea starch, chickpea starch, bean starch, lentil starch, non-foam banana starch. 17. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED WITH ADHESIVED AND ADDITIVE STARCH AND PVA, according to claim 1, characterized by the incorporation of active agents that promote agricultural productivity. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE starch and PVA composition according to claim 1, characterized by the aggregation of deferensants and / or growth agents and / or amino acids into the composition of the foamed product. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE starch and PVA constituted according to claim 1, characterized by the aggregation of sodium nitrate (Chile saltpeter), potassium nitrate, ammonium nitrate, calcium sulphate, magnesium sulphate, urea, superphosphates and phosphites or their mixture in the composition of the foamed product. A SUPERABSorbent POLYMER FOR USE IN AGRICULTURE CONSTITUTED WITH ADHESIVE AND ADDITIVE STARCH AND PVA, according to claim 1, characterized by increased water absorption over time of use. SUPERABSorbent POLYMER FOR USE IN AGRICULTURE RETIMULATED AND ADDITIVE STARK AND PVA CONSTITUENTS according to claim 1, characterized in that they contain intermediate biodegradation products which do not accumulate or exhibit total absence of toxicity in the agricultural environment. Method of preparation according to claim 1, characterized in that the foam production comes from the starch and is processed by thermoexpansion, extrusion, thermo-pressing, or any other process known by the state of the art. Preparation according to Claim 1, characterized in that the plasticizers, thickeners, organic and inorganic fillers and pigments are added to the superabsorbent polymer. Preparation method according to claim 1, characterized by the inclusion of maize, cassava, potato, rice starch, among others, in concentrations of 50 to 90%, according to the equipment and process used in the preparation of the superabsorbent polymer. Preparation method according to claim 1, characterized by the inclusion of maize, cassava, potato, rice starch, among others, in concentrations of 50 to 60%, according to the equipment and process used in the preparation of the superabsorbent polymer. Preparation method according to claim 1, characterized by the inclusion of maize, cassava, potato, rice starch, among others, in concentrations of 61 to 70%, depending on the equipment and process used in the preparation of the superabsorbent polymer. Preparation according to Claim 1, characterized by the inclusion of maize, cassava, potato, rice starch, among others, in concentrations of 71 to 90%, depending on the equipment and process used in the preparation. superabsorbent polymer. Preparation according to Claim 1, characterized in that additives are added at concentrations ranging from 0.005% to 70% according to the equipment used in the preparation of the superabsorbent polymer. Preparation according to Claim 1, characterized by the aggregation of plasticizers of the polyol family in concentrations from 2% to 10% according to the equipment used in the preparation of the superabsorbent polymer. Preparation method according to Claim 1, characterized in that water-soluble polymer such as PVA and copolymers are added in concentrations from 10% to 40% according to the equipment used to prepare the superabsorbent polymers. Method of preparation according to claim 1, characterized in that the aggregation of crosslinking agents in concentrations between 0.001% and 10%, according to the equipment used in the preparation of the superabsorbent polymer. Method of preparation according to claim 1, characterized in that the glutaraldehyde and borate disodium aggregate, or a mixture thereof, as cross-linking agents, at concentrations between 1% and 5%, depending on the equipment used in the preparation of the superabsorbent polymer. Preparation according to claim 1, characterized by the aggregation of active agents in concentrations ranging from 0.01% to 50%, as used in the preparation of the superabsorbent polymer. Preparation method according to Claim 1, characterized in that the aggregate of fertilizers and decreasing agents or mixtures thereof in concentrations between 0,01% and 10% according to the equipment used in the preparation of the superabsorbent polymers. Preparation according to claim 1, characterized by the addition of additives such as inorganic, inorganic fillers, pigments and dyes in concentrations between 0.01% and 20%, depending on the equipment used in the preparation of the superabsorbent polymer. Preparation method according to Claim 1, characterized in that the additives and cross-linking agents are added to the mixture pure or dissolved in suitable solvents. Preparation according to Claim 1, characterized in that the mixture is prepared at a temperature which may vary from 30% to 220 ° C depending on the type of additive starch added. Preparation method according to Claim 1, characterized in that the foamed product is ground to a temperature which may vary from -190 ° C (with the aid of liquid nitrogen) to 130 ° C, depending on the material to be processed and the process used. Preparation method according to Claim 1, characterized in that the foamed product is dried at a temperature of 60 ° C to 250 ° C, depending on the cross-linking additives and agents used in the preparation of the product. Preparation method according to Claim 1, characterized in that the foamed product comprises between 5 and 10 mesh. Method of preparation according to claim 1, characterized in that the foamed product has degranulometries between 11 and 20 mesh. Preparation method according to Claim 1, characterized in that the foamed product has degranulometries between 21 and 30 mesh.