MXPA97003478A - Implantable device for administering active substances to plan - Google Patents

Abstract

The present invention relates to an implantable device for the release of substances to plants, wherein said device is a ceramic molded article that is interspersed with pores and in which the active substance is distributed in open pores, the volume of pores in the moment of implantation is dimensioned so that it comprises the quantity of the total active substance that will be released with the class of the total porosity, its volume, size and dispersion, as well as the distribution of the pores being determinable within the limits

Description

PLANTABLE I DEVICE FOR ADMINISTERING ACTIVE SUBSTANCES TO PLANTS The invention relates to an implantable device for administering active principles to plants. BACKGROUND The supply of active ingredients to plants by means of implantable devices is known per se and has been mentioned in the specialized literature. Examples can be found in patents JP 58039602 and AU 84 31497. Patent publication JP 5803 9602 discloses expandable and implantable active substance systems consisting of a mixture of hydrophilic and water-absorbing polymers. The principle of operation of these systems is such that the release of the active principle occurs as a result of a solubilized and, therefore, is controlled by the recovery of water in the plant. However, this regulation mechanism has the following disadvantage. Because the release of active principle occurs according to the level of water absorption, the release rates depend on the state of hydration of the cells of the plant tissue at the site of application. However, the degree of cellular hydration is exposed according to the experience to important fluctuations, where the range of fluctuation depends on the balance of water in the plant. Extremely low or high water potentials of the plant cells can cause an interruption of the release of the active ingredient or a rapid release thereof and as a consequence, can lead to premature depletion of the system. In these systems it is not possible to achieve long-term control and to be reliable in the amount of active ingredient to be supplied per unit of time. In the case of patent AU 843 1497, it is a delivery system developed mainly for irrigation and fertilization purposes. It consists of a porous ceramic implant and an external tank of gas or liquid, connected to each other. The administration of water and the active principle occurs in this case through the use of the capillary forces of the implanted body, the normal flow of the transpiration of the plant representing the driving force necessary for the transport of the carrier liquid of the active principle. The control of the liquid flow and the corresponding administration of active principle to the plant's conductor system is thus entrusted to the plant itself. It follows that this system is not suitable for an exact dosage of the active principle, not allowing its application in the administration of phytosanitary agents or regulators of plant growth. In the protection of plants in forestry and gardening it is important to adapt the requirements of active principle to the specific needs of the respective host-pathogen relationship (temporal relationship between the disease and the development of the pathogen, height of the respective threshold of economic damage). Not least, the rate of release of the active ingredient also affects the cost situation in the treatment of for example, a larger park of plants or trees. DESCRIPTION OF THE INVENTION The present invention aims to deliver an implantable device suitable for supply the active principles to the plants, where the coupling of the release of the active principle with the water balance of the plant is limited to a minimum, allowing to control the release rate of the active principle avoiding the difficulties and the technical limitations indicated above. The objective has been achieved with the help of an implantable device having the characteristics indicated in claim 1. Further suitable embodiments of the device are disclosed in the subclaims. Here, it was surprisingly discovered that in the system provided with hollow spaces of the porous ceramic bodies, it is possible to epositar active ingredients, which are released after having introduced the aforementioned ceramic bodies also in the organs made of the plants. The objective of the invention is an implantable device suitable for supplying active principles to the plants in the form of a formed body provided with pores, where the active ingredient is distributed in open pores and at the time of implantation, the volume of the pores is of such a size that it contains the entire quantity of the active ingredient to be supplied. Among the important characteristics of the device according to the invention is the type and the order of magnitude of the total porosity, that is to say, the volume and the dispersion as well as the distribution of the pores. Since in the hollow porous system of the porous body must deposit or introduce required amounts of active ingredients, the parameters mentioned above are of decisive importance from the point of view of the release of the active principle. The advantage of the device according to the invention resides in the use of its pore system as a driving and regulating force in the release of the active principle. This allows the release of the active principle from the water balance of the plant to be decoupled to a greater extent. As raw materials for the manufacture of the device according to the invention, different clay minerals can be used, such as, for example, AI2O2 x 2 SiO2 x 2 H2O to AI2O3 x 4 SiO2. Here we can mention, for example, kaolins (kaolinite, allophane, halosite), illites (glauconite), smectites (montmorilonite, nontronite, beidelite) and vermiculite, where they are preferably present in the form of mixtures. Said clays are characterized in that they swell or expand in the humerus state and can be deformed plastically, but once dried they maintain their shape and when they are calcined at a temperature between 800 ° C and 2000 ° C, preferably between 1000 and 1200 ° C, harden with formation of swollen pores. Particularly suitable materials are kaolinites, litas and halostite, which are usually used as ceramic materials in different fields of application. If clays (mixtures of different materials) are used in the manufacture of the device of the invention, then their mineralogical composition as well as their granulometry must be known, because these parameters determine the properties and particularly the proportion of the pores of the body. ceramic formed. However, the device can be ceramic porous shaped bodies, similar to the expanded concrete of mineral raw materials capable of hydraulically setting and whose porous component is obtained by means of an adjustable chemical reaction of the components. In order to influence the structure of the pores, the specialist has the following alternatives. Choice of clay minerals, variation of the size of the primary particles, the incorporation of auxiliary materials and variation of the conditions (temperature and time) of the manufacturing process, either by means of a thermal process or also a reactive process. According to the present invention, the starting materials are chosen in such a way that the implantable device manufactured therefrom has an open pore structure with a pore volume of about 70 to 95%, especially 80%. The pore size spectrum of the device of the invention is relatively broad, comprising values of 0.05 to 5.0 micrometers (μm). as preferred range of pores is mentioned that comprised between 0.1 and 2.0 μ. If clay minerals are used with the same primary particle size, then a relatively homogeneous pore spectrum (reduced pore size control) is generally achieved. The granulometric size of the materials used can be determined by means of baking or sedimentation in the water. As a preferred particle size, the range <may be mentioned; _ 2 μm. By varying the particle size it is possible to control the porosity. Another possibility for varying the porosity of the device of the invention consists in the incorporation of different auxiliary materials during its manufacture. It is a known fact that during the manufacture of ceramic products there is a reduction in the volume of pores caused by the elimination of water. In order to compensate for a possible reduction in the volume of the pores, the so-called lean agents are applied. With the help of these agents or substances, the eliminated water is replaced by pores of air. Among the compensating materials, mention may be made, for example, of silicic acid (in the form of quartz or quartzite) or ground refractory materials. The use of lean agents simultaneously promotes the mechanical strength of the final product.

Other auxiliary materials that allow to improve the product and that can be applied in the manufacture of the device according to the invention, are the pore-forming agents. Among these are the organic fibrous materials such as pulp of paper or other combustible materials, such as brown coal, limestone and expanded polystyrene These materials are incorporated into the mass of the raw material and subsequently combusted during the process of the gassing process. Alternatives for controlling the porosity of the device according to the invention can be Lastly, mention should be made of the thermal conditions of its manufacture, in particular the combustion conditions. As the combustion temperature increases, a reduction of the porosity and an increase of the mechanical properties of the ceramic products are produced. conditions of the combustion of the different states of the combustion, in such a way as to obtain the required porosity properties of the device according to the invention. As the preferred combustion temperature, the range of 950 to 1050 or 1000 to 1200 ° C is mentioned. To load the material with the active principle it is immersed the device of the invention (porous formed body) in an aqueous solution of the active ingredient By means of the concentration of the active principle in the solution, it is possible to control the content of active principle in the device. Optionally, the impregnated with the active ingredient in order to reach higher contents of active principle According to the invention, between 1 to 20% by weight of active principle can be incorporated in the device, where the active principles can be present in isolated form or in mixtures between Yes Among the active ingredients, you can basically use all the materials that influence the phenomena In the plant or animal organism within the framework of the present invention, phytosanitary agents such as fungicides and insecticides are preferably used. Explanatory, but not limiting examples of the active ingredients that can be supplied to plants by the devices of the invention , are the following - fungicides, for example, benomyl, bromoconazole, bitertanol, ethaconazole, flusilazole, furalaxyl, foset-1-A1, imazalil, metalaxyl, penconazole, propioconazole, thiabendazole, tpadimefon, tpadimenol or triforma, - insecticides, for example butocarboxime , dimethoate, phenoxycarb, metamyl, oxamyl, oxidemteton-methyl, pipmicarb, propoxur, - fertilizers, for example superfosate, Thomas phosphate The devices of the invention can be obtained as pieces formed with different geometries Among the especially preferred pieces can be mentioned those cylindrical , in the form of sticks or balls Conveniently, they have measures s that allow a simple manual operation Generally the size of the piece ascends to 2.0 to 100 mm, preferably of 5.0 to 50 mm A particularly convenient embodiment of the implant according to the invention, is a device where one or several pieces ceramic tiles are fixed on a rigid plate The plate consists of a resistant and tolerable material for the fabric of the plant Particularly suitable for this is the wood The special advantage of this embodiment is that the plate that closes the hollow space in the plant, forms a protective cover, eliminating the possibility of an exit of the active principle or at least minimizes it. The device according to the invention is implanted in the growth or sprouted axis of the plant, being introduced in spaces previously created holes (for example perforations) The device is particularly suitable to be applied in plants that have lignifica shoots two (shrubs and trees) The invention will be explained by the following example Example 1 A 500 g of a clay mixture formed by equal parts by weight of blue clay Wittershlicker 38/40 and blue clay Satzvveyer with a moisture content of 15 % and with the following granulométpca distribution Particle size% by weight Diam in μm >; 63 2.0 63-20 1.7 20-6.3 1.7 6.3-2.0 7.2 < 2.0 88.4 25 g of expanded sawdust were incorporated into the water by means of mechanical mixing. The moisture content of the table thus obtained was then increased by incorporating water up to 40% by weight. The plastic mass obtained was first elaborated in a extruder a "fideoX type product which is then cut into cylindrical shaped elements (6 cm x 2 cm x 1 cm) The raw elements thus obtained were dried in a drying chamber at 30 ° C for a period of 24 hours Then the dried product was calcined in an electric oven (Firma Naber-Thern) with a continuous increase in temperature The residence time of the raw material in the main combustion zone (950 ° C) was 1.5 hours After When the pieces formed were cooled, their definitive dimensions (5.1 cm x 1.7 cm x 0.84 cm) and the total porosity (60%) were determined. To load the elements with the active principle they were impregnated with a solution of 10 % of fosetyl The amount of principle The active ingredient incorporated into the porous system, determined through the variation of the weight of the device and the concentration of the active principle in the solution, was 0.2 g / device. Through the present invention there is a very simple device, easy to use and economical to supply the active principle, being particularly in cities, where the chemical treatment of trees is problematic, a valuable alternative in comparison with conventional techniques .

Claims (1)

1. CLAIMS 1 A device that is self-sufficient, is implantable in plant cavities and comprises a quantity of active substances that have an effect on the plants, said active substances being supplied to the plant during the duration of the implant, characterized by a porous ceramic body open whose total pore volume is impregnated with the solution of active substance or dispersion of active substance and whose pore size and pore distribution is adapted to the desired release rate of active substance, said overall pore volume being sufficient to receive said amount of active substance, which is present in dissolved or dispersed form 2 The device according to claim 1, characterized in that the ceramic body consists of mineral-based materials baked at temperatures between 800 ° C and 2000 ° C, preferably between 1000 and 1200 ° C, the materials being selected from the following mineral groups of clay: kaolins (kaolinites, allophones, haloes), mitas (glauconite), smectites (montmoplonite, nontronite, beidelite), chlorites and vermiculites 3. The device according to claim 1, characterized in that the ceramic body consists of base materials mineral that is hydraulically stable and has a pore volume caused preferably by chemical reaction 4. The device according to claims 1 to 3, characterized in that the pores of the ceramic body are formed during the baking process essentially by degradation of heat degradable additives, mixed, in particular of the group consisting of sawdust, paper pulp, lignite, expanded polystyrene, pumice stone and clay powder. The device according to one or more of claims 1 to 4, characterized in that the ceramic body has a pore size spectrum with values of 0.05 to 5.0 μm, preferably between 0.1 and 2.0 μm. The device according to one or more of claims 1 to 5, characterized in that the active substances contained are systemically or systemically local protection agents of active plants, plant restorers, growth regulators, nutrients or other agents for the control of biological processes. The device according to one or more of claims 1 to 6, characterized in that it is connected to a protective cover in the form of a plate which is suitable for closing the cavity in the plant. 8. The use of the device according to one or more of the preceding claims to be implemented in several pre-formed cavities of the shoots apices of the plants. 9. A process for the production of the device according to one or more of claims 1 to 7, characterized in that first a molded ceramic article is formed and the active substance present in a fluid form is incorporated therein by means of impregnation .