JP2005319417A - Particle coating apparatus and production method for coated particle using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle coating apparatus capable of stably producing coated particles with high quality while maintaining high productivity and a production method for coated particles using the apparatus. <P>SOLUTION: The particle coating apparatus comprises: a fluidizing tank for fluidizing core particles by a high-temperature gas and capable of keeping temperature for spraying a coating solution containing an organic solvent and a coating material to the core particles; a transportation path for keeping temperature for discharging a gas containing the evaporated organic solvent out of the fluidizing tank; a gas-solid separator for separating solid matters such as particle fragments and coating dust accompanied with the gas containing the evaporated organic solvent; a condenser for separating the organic solvent from the gas containing the evaporated organic solvent after the solid matter removal; and a blower for supplying the gas to the fluidizing tank by heating the gas after the organic solvent removal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a particle coating apparatus for forming a coating on the surface of core material particles such as fertilizers, agricultural chemicals, pharmaceuticals, and foods, and a method for producing coated particles using the same.

  Conventionally, as a coated particle manufacturing apparatus, a coated granular fertilizer manufacturing apparatus using fertilizer particles as a core material is known. Specifically, a jet tower to which fertilizer particles are supplied, a throttle section for ejecting gas upward from the bottom of the jet tower, a guide pipe installed above the throttle section, and a coating material dissolved or suspended in the guide pipe An apparatus having a spray nozzle for spraying the applied coating liquid is known (see, for example, Patent Document 1).

  The coated granular fertilizer manufacturing apparatus is a jet-type apparatus that adheres and dries the coating liquid while allowing the fertilizer particles to flow as a jet, and the fertilizer particles supplied into the jet tower are guided by the gas ejected from the throttle section. The spray nozzle sprays the coating liquid in which the coating material containing the resin is dissolved or suspended in an organic solvent while blowing up with a gas that blows up the fertilizer particles that fall from the upper end of the guide pipe to the surroundings while repeating this process. Is sprayed onto the fertilizer particles, and after the spraying of a predetermined amount and the vaporization of the organic solvent is completed, the supply of gas from the throttle portion is stopped, and the coated fertilizer particles are dropped from the throttle portion and discharged.

  In the production of the coated particles as described above, stable quality, maintenance of high productivity, and satisfactory physical properties are required. However, in order to achieve high productivity, it is obvious that the coating liquid spray speed, coating liquid concentration and vaporization speed should be increased, but it is difficult to stably obtain products of the target quality. As a result of disturbance factors such as temperature changes around the manufacturing equipment and coating waste due to frequent coating failures, the load of the solid-gas separator is increased, and there is a balance between the ejection of gas in the equipment, the concentration of organic solvent in the gas, temperature, etc. It tends to collapse. In particular, when the outside air temperature drops drastically due to rain or the like when the spray speed is extremely high, the temperature balance in the device is disrupted, and the organic solvent contained in the gas is condensed in the device, resulting in the formation of coated particles. There was a problem that the coating was defective and the device was contaminated, and further, it was difficult to remove the solvent in the product-coated particles.

  Also, in the transport path from the organic solvent vaporized in the fluidized tank and the solids such as floating core particle debris and coating waste to the solid gas separator after being discharged from the gas outlet of the fluidized tank together with the gas. When the solid matter that floats becomes wet, the solid matter tends to stick, the gas flow deteriorates, the organic solvent is condensed in the apparatus such as the fluid tank, the conveyance path, and the solid-gas separator, and the solid matter becomes solid and solid. In addition to depositing in the separator and causing clogging, it becomes impossible to produce coated particles, and in order to remove the clogging in the solid-gas separator, etc., stopping the equipment or opening the equipment reduces productivity. It was a problem due to leakage of organic solvent.

The range of apparatus operating conditions in the gas circulation process is limited by the coating conditions in the fluidized tank that affect the quality of the product. The non-condensing range determined by the saturated vapor pressure curve can be predicted from the coating liquid spray rate (spray speed), gas temperature, gas flow rate, etc., but conditions close to the dew point are necessary to increase productivity. is there.
In addition, if the entire apparatus is enlarged, it can be operated within a safe range in which the organic solvent does not condense, and the production amount can be secured. However, since the utility cost such as equipment cost and electricity cost increases, it goes against the low cost. Therefore, a manufacturing apparatus and a manufacturing method with high thermal efficiency of facilities are required.

JP-B-2-31039

  An object of the present invention is to provide a particle coating apparatus capable of producing high quality coated particles stably while maintaining high productivity, and a method for producing coated particles using the same.

  The present inventor has intensively studied to solve the above problems. As a result, a fluid tank capable of maintaining heat for causing the core particles to flow by supplying a high-temperature gas, spraying a coating liquid composed of an organic solvent and a coating material onto the core particles, and vaporizing the organic solvent to form the coated particles. , A heat-containable transport path for discharging the gas containing the vaporized organic solvent from the fluidized tank, and a solid-gas separator for separating solids such as particle fragments and coating waste accompanying the gas containing the organic solvent A particle coating apparatus having a condenser for separating the organic solvent from the gas containing the organic solvent after removing the solid matter, and a blower (blower) for heating and supplying the gas after removing the organic solvent to the fluidized tank The present invention has been completed by finding that the problems can be solved.

The present invention is constituted by the following.
(1) A fluid tank capable of maintaining heat for causing core particles to flow by supplying a high-temperature gas, spraying a coating liquid composed of an organic solvent and a coating material onto the core particles and vaporizing the organic solvent to form the coated particles. , A heat-containable transport path for discharging the gas containing the vaporized organic solvent from the fluidized tank, a solid-gas separator for separating the solids entrained in the gas containing the organic solvent, and the organic after the solids are removed The particle coating apparatus which has a condenser for isolate | separating an organic solvent from the gas containing a solvent, and a blower for heating the gas after organic solvent removal, and supplying it to a fluidized tank.
(2) The particle coating apparatus according to (1) above, wherein the solid-gas separator can be kept warm.
(3) The particle coating apparatus according to (1) or (2), wherein the heat source for heat insulation is water vapor.
(4) The particle coating apparatus according to any one of (1) to (3), wherein the solid-gas separator is one or both of a cyclone and a bag filter.
(5) The particle coating apparatus according to any one of (1) to (4), wherein the core material is fertilizer.
(6) A method for producing coated particles using the particle coating apparatus according to any one of (1) to (5).

In the particle coating apparatus of the present invention, the fluid tank and the conveyance path can be kept warm, so that dew condensation in the facility can be prevented, and as a result, the solid-gas separator can be prevented from being blocked and stable coating conditions can be obtained. Can keep. By using this apparatus, it is possible to form a uniform coating, and it is possible to produce high-quality coated particles having a very excellent elution control function with few defects in the coating with high productivity. .
Moreover, since the frequency | count of cleaning of a solid-gas separator reduces, the improvement of productivity can be achieved and the loss of the organic solvent by equipment opening can be reduced.

Below, the particle coating apparatus of this invention and the manufacturing method of the coated particle | grains using the same are demonstrated in detail.
The particle coating apparatus of the present invention will be described with reference to FIG. The coating apparatus includes a fluid tank (jet tower) 1, a solid-gas separator 4 that separates solids such as debris of core material particles and coating waste from a gas, and an organic solvent contained in the gas from which the solids are removed by cooling or the like. A condenser 5 for condensing and separating, a blower 6 for circulating and blowing a gas, a heater 7 for heating a gas to vaporize an organic solvent, and a device for supplying a coating liquid through a spray nozzle 2 (a coating material dissolving tank 8 and a coating liquid pump 9 ), And a transport path connecting them.

The jet tower 1 sprays the coating liquid (coating material dissolution / suspension) with the spray nozzle 2 on the core material particles 3 in a fluidized state by the spray nozzle 2 and sprays them onto the surface of the core material particles 3. At the same time as covering the surface, a high-temperature gas (air containing an organic solvent and water) heated in parallel by the heater 7 is caused to flow from the lower part of the jet tower 1 through the rectifier 11 into the fluidized tank by the blower 6, The organic solvent in the coating liquid adhering to the surface of the core material particles is instantly vaporized by the gas.
The newly vaporized gas containing the organic solvent is discharged from the upper part of the jet tower 1, and after passing through the solid-gas separator 4 for separating and removing solids, it is cooled by the condenser 5, and most of the organic solvent and moisture are removed. Is stored in the organic solvent tank 12 after being condensed and recovered, and is reused for dissolving the coating material again. Most of the organic solvent and the gas mainly composed of air from which moisture has been removed are sent again to the jet tower 1 via the blower 6 and the heater 7. During the coating operation, the temperature of the hot gas entering the jet tower 1 is controlled so that the particle temperature T2 becomes a predetermined temperature. Here, the particle temperature refers to the surface temperature of the particle (core material) and is a temperature measured in a state where the particle (core material) exists around the temperature measuring terminal. The coated particles coated with a predetermined amount of the coating material are discharged from the coated particle extraction port, and usually become a product through the solvent removal processing device 13 and the surface processing device 15.

The operation method of the particle coating apparatus of the present invention may be a batch type or a continuous type. For example, when performing a coating operation by batch operation using a spouted bed coating device, a fixed amount of particles are charged into a spout tower, a predetermined amount of coating material is sprayed onto the particle surface, and then the coated particles are removed from the spout tower. Discharge. Thereafter, a certain amount of particles are newly charged into the jet tower and the same operation as described above is performed.
As a coating apparatus that can be used in the present invention other than the apparatus shown in FIG. 1, as a fluidized bed type or spouted bed type coating apparatus, disclosed in Japanese Patent Publication Nos. 42-24281 and 42-24282, An apparatus that forms a fountain-type fluidized bed of particles with a gas body and sprays a coating agent on a particle-dispersed layer formed in the center can be exemplified.
Further, as a rotary type coating device, the powder particles are moved upward by a lifter provided on the inner periphery of the drum by the rotation of the drum disclosed in JP-A-7-31914 and JP-A-7-195007, and then dropped. An apparatus for applying a coating agent to the surface of a falling granular material to form a film can be mentioned.

In the present invention, the fluid tank (jet tower) and the transport path for transporting the organic solvent vaporized in the fluid tank by gas can be kept warm, and further, solids such as particle fragments and coating waste are separated from the gas. Therefore, it is desirable that the solid-gas separator can be kept warm.
Insulation of the transport path to the condenser that transports the vaporized organic solvent vaporized in the fluid tank and the fluid tank simply by surrounding the outer periphery of the transport pipe with a heat insulating material and blocking the escape of the heat of the gas to the outside Although effective, it is more effective to provide heating means on the outer periphery of the transport pipe to actively heat the transport path. As a result, dew condensation in the transport path can be completely prevented, and even when the transport path is cold at the start of operation, the transport path can be raised to the gas temperature by heating. As the heating means, it is most preferable to employ a steam trace in which a pipe through which water vapor passes is arranged on the outer periphery of the transport pipe. The temperature of the water vapor passing through the pipe is preferably 130 to 180 ° C., and the temperature inside the transport pipe can be adjusted by adjusting the amount of water vapor passed through. As a heat source for heating, in addition to water vapor, heating may be performed using hot water (60 to 100 ° C.) or electricity.

  By performing heat insulation by heat insulation or heating of the fluid tank and the conveyance path, a decrease in the gas temperature during conveyance and the temperature of the inner wall of the transport pipe is prevented. The gas temperature during conveyance does not need to be kept constant as long as it is maintained at a temperature at which condensation does not occur. A problem due to condensation substantially occurs in the fluid tank and the conveyance path when the gas temperature or the inner wall temperature of the transport pipe is lowered to a temperature lower than 3 ° C. Therefore, the heat retention of the fluid tank and the conveyance path is preferably adjusted so that the gas temperature or the inner wall temperature of the transport pipe is 3 ° C. or more, preferably 5 ° C. or more higher than the dew point.

In the present invention, the case where the solid-gas separator is kept warm is the same as the case where the fluid tank and the conveyance path are kept warm. As the solid-gas separator, it is preferable to use either or both of a cyclone having a high removal efficiency of relatively large particles (particle size of 5 μm or more) and a bag filter having a high removal efficiency of small particles (particle size of 1 μm or more). These can be arbitrarily selected depending on the conditions of the particle coating apparatus. However, the combined use of the cyclone and the bag filter has an advantage that the apparatus is less contaminated because it can efficiently remove small particles.
The cyclone is a centrifugal separator that imparts a swirling motion to the dust-containing gas and separates the particles from the gas by centrifugal force acting on the particles, and examples thereof include a tangential inflow type and an axial flow guide vane type. Among these, the tangential inflow type having the simplest structure is preferable.
The structure of the bag filter varies depending on each model. For example, in the case of a pulse air type bag filter, the bag filter is generally constituted by a housing part, a top plenum part, a hopper part, and a filter cloth. A general filter cloth is a cylindrical bag having a diameter of 15 to 50 cm and a length of 1 to 5 m, and the material or the like is selected depending on the conditions during use. A bag filter using a cartridge-type filter is preferable in terms of installation area, maintainability, and dust removal performance. Specific examples include a TD type and a downflow type manufactured by Nippon Donaldson.

  In order to use the solid-gas separator as designed, it is necessary to prevent condensation. Especially in bag filters that are easily clogged, collect the housing part (iron skin around the bag filter) and solid matter containing the filter cloth. Cover the outer periphery of the hopper with a heat insulating material to keep it warm. Preferably, the heating is positively performed in combination with a heating means such as steam trace. You may have heating means, such as a steam trace, inside the solid-gas separator. The degree of heat retention can prevent condensation in the solid-gas separator by adjusting the temperature in the same manner as the conveyance path.

As the solids separation performance of the solid-gas separator, a JIS 7 standard powder (JIS Z8901 test dust, medium diameter 30 μm) was filtered at a rate of 1.5 m / min, and the dust input per unit filtration area was 2000 g / m ² ( Under a measurement condition of a dust concentration of 0.88 g / m ² ), an absolute filter is provided immediately after the air filter, air is drawn with constant air flow control, dust is sucked into the air filter, dust removal efficiency = 100 × (1 It is preferred that the value calculated by (absolute filter weight increase / total input dust weight) has a performance of 95.0% or more, preferably 99.5% or more. In particular, solids with a particle size exceeding 5 μm include poorly coated film scraps and core materials such as urea crushed during flow, etc., from which contamination of the equipment in the transport pipe and the circulation system is prevented. Contributes to the stable operation of equipment and the maintenance and improvement of product quality.

  In the present invention, in order to prevent dew condensation in the fluid tank and the conveyance path, more preferably in the solid-gas separator, the temperature of the gas tank is prevented from being lowered by keeping them warm. However, if the conveyance path inlet (fluid tank outlet) temperature is maintained up to the condenser, the load on the condenser increases, and accordingly, the equipment cost and running cost are also increased. Therefore, the conveyance path from the solid-gas separator outlet to the condenser inlet does not have to be heated. However, since the outside air temperature is lower in winter and the gas temperature to the condenser inlet is lower than in summer, the condenser position is placed on the transport path from the solid-gas separator to the condenser to prevent condensation. It is preferable to provide a downward slope, for example, by lowering.

The amount of heat supplied by the high-temperature gas is used for the latent heat of vaporization of the organic solvent in which the coating material is dissolved or suspended. Therefore, in the steady state, the temperature of the high-temperature gas and the surface temperature of the coated particles (core material) are respectively The gas temperature after vaporizing the organic solvent is also substantially constant depending on the type of the solvent. However, if the coating operation is performed with a device that cannot maintain heat, a fluidized tank with a high concentration of organic solvent in the gas, a transport path from the fluidized tank outlet to the condenser, and a solid phase due to fluctuations in the outside temperature due to daytime, season, and weather. The dew point in the air separator may fluctuate, leading to condensation.
The temperature of the hot gas is appropriately selected according to the operating conditions of the apparatus so that the amount of heat required for vaporization of the organic solvent is supplied, but in a steady state where the coating operation is actually performed. 110-175 ° C is common.

  If the particle coating apparatus of the present invention is used, it is possible to suppress dew condensation at the above-mentioned part of the apparatus, so that the product has fewer coating defects, the apparatus has less fouling, has long-term operational stability, and unprecedented productivity. It is possible to perform coating operation with excellent environmental conservation. This is because the gas temperature at each part of the device is stable and less susceptible to sudden temperature changes around the device, compared to a device in which the device of the present invention is not capable of keeping warm. It is thought that one reason is that the vaporization of the solvent can be maintained well.

  The particle coating apparatus of the present invention includes a desolvation processing apparatus for completely removing and recovering the organic solvent remaining in the coated particles that have been coated in the fluidized tank and then withdrawn from the outlet, and further the deorganic solvent It is preferable to install a surface treatment apparatus for performing a treatment according to the application on the surface of the coated particles. Moreover, it is preferable to install a thermometer for measuring the gas temperature in the lower and upper portions in the fluid tank, the fluid tank outlet, the solid-gas separator, the condenser, and the gas conveyance path passing through these devices. . The guide tube (10 in FIG. 1) of the fluid tank is cylindrical and can stably generate a jet, and may be fixed or movable. As the gas used in the present invention, an inert gas such as air or nitrogen is appropriately used depending on the substance contained in the coating liquid. The shape of the spray nozzle for spraying the coating liquid is not particularly limited, and may be appropriately selected in consideration of the amount of spray, the concentration of the coating liquid, and the like.

  The method for producing coated particles of the present invention uses the particle coating apparatus described above. In this production method, the particles to be coated (core material) are not particularly limited, and various particles such as fertilizers, agricultural chemicals, foods, and pharmaceuticals can be used as long as they are granular. This production method is particularly suitable for the production of fertilizer and agricultural chemical coated particles that require mass production.

  When the core material is a granular fertilizer, the active ingredient is not particularly limited, and conventionally known ones can be used. Examples of the fertilizers include nitrogenous fertilizers, phosphate fertilizers and calcareous fertilizers, as well as fertilizers containing plant essential elements such as calcium, magnesium, sulfur, iron, trace elements and silicon. Nitrogenous fertilizers include ammonium sulfate, urea, ammonia nitrate, isobutyraldehyde condensed urea, acetaldehyde condensed urea, etc., and phosphoric fertilizers include lime superphosphate, molten phosphorus fertilizer, calcined phosphorus fertilizer, etc. Examples of the calcareous fertilizer include potassium sulfate, potassium chloride, and potassium silicate fertilizer, and the form is not particularly limited. Moreover, the advanced chemical fertilizer and compound fertilizer whose total component amount of the three elements of a fertilizer is 30% or more, Furthermore, organic fertilizer may be sufficient. Further, it may be a fertilizer to which a nitrification inhibitor or a pesticide is added or adhered. Further, the active ingredient may be one type or may be composed of two or more composite components.

  When the core material is an agrochemical granule, the active ingredient is not particularly limited, and conventionally known ones can be used. Specific examples include a disease control agent, a pest control agent, a harmful animal control agent, a weed control agent, and a plant growth regulator, and any of these can be used without limitation. A disease control agent is a chemical | medical agent used in order to protect agricultural products etc. from the harmful effect of a pathogenic microbe, and a disinfectant is mainly mentioned. A pest control agent is a chemical | medical agent which controls pests, such as agricultural crops, and an insecticide is mainly mentioned. The harmful animal control agent is a drug used for controlling plant parasitic mites, plant parasitic nematodes, wild boars, birds, and other harmful animals that harm crops and the like. The weed control agent is a drug used for controlling a plant or plant that is harmful to agricultural crops or trees, and is also called a herbicide. A plant growth regulator is a drug used for the purpose of enhancing or suppressing the physiological function of a plant.

  The pesticide is preferably in the form of a solid powder at room temperature, but may be liquid at room temperature. In the present invention, the pesticide can be used regardless of whether it is water-soluble, poorly water-soluble or water-insoluble. Further, the active ingredient may be one type or may be composed of two or more composite components.

  The core particles used in the present invention may be those containing one or more of the above-mentioned active ingredients, but as long as the effects of the present invention are not impaired, clay, kaolin, talc, It may contain a carrier such as bentonite or calcium carbonate, or a binder such as polyvinyl alcohol, sodium carboxymethyl cellulose, or starch. Further, if necessary, for example, a surfactant such as polyoxyethylene nonylphenyl ether, molasses, animal oil, vegetable oil, hydrogenated oil, fatty acid, fatty acid metal salt, paraffin, wax, glycerin, etc. I do not care. Further, the particles described above may be coated with a resin or an inorganic material.

  The particle diameter of these core particles is not particularly limited. For example, in the case of fertilizer, it is 1.0 to 10.0 mm, and particularly preferably 1 to 5 mm. In the case of an agrochemical, it is preferable that it is 0.3-3.0 mm. By using a sieve, any particle size can be selected within the above range.

  As the granulation method of the core material particles, extrusion granulation method, fluidized bed granulation method, dynamic rolling granulation method, compression granulation method, coating granulation method, adsorption granulation method, and the like can be used. Any of these granulation methods may be used in the present invention.

The shape of these core material particles is preferably close to a spherical shape, and those having a narrow particle size distribution are preferable from the viewpoint of elution characteristics. Specifically, the circularity coefficient obtained by the following formula is preferably a sphere having a sphericity of preferably 0.7 or more, more preferably 0.75 or more, and still more preferably 0.8 or more. The maximum value of the circularity coefficient is 1, and as the value approaches 1, the particle approaches a perfect circle, and the circularity coefficient decreases as the particle shape collapses from the perfect circle.
Circularity coefficient = {(4π × projection area of particle) / (length of contour of particle projection) ² }

  For example, from an elution suppression period (hereinafter referred to as d1) in which elution of an active ingredient is suppressed for a certain period after application, and an elution period (hereinafter referred to as d2) in which elution of the active ingredient continues after a certain period after application. In the coated particles having a timed elution type elution function, when the core particles having a circularity coefficient of less than 0.7 increase, elution of the coated particles having a timed elution type elution function obtained using the particles at d1 Since the suppression tends to be insufficient and the active ingredient tends to leak, the core material particles preferably have a circularity coefficient of 0.7 or more.

In the particle coating apparatus and the method for producing coated particles of the present invention, the coating material used for coating the core particles is not particularly limited, but is included in the case of producing time-dissolved coated particles. A material and composition that can strictly control the elution of the active ingredient to be selected may be selected. Examples of such coating materials include inorganic coating materials typified by sulfur, thermosetting resins such as phenolic resins, alkyd resins, and polyurethanes, and thermoplastic resins such as polyolefins such as polyethylene and polypropylene, and polyvinylidene chloride. .
Of these, when coating particles containing active ingredients that require strict and long-term elution control, such as fertilizers and agricultural chemicals, it is preferable to use a thermosetting resin or a thermoplastic resin as the coating material, If high elution control is necessary, it is particularly preferable to use a thermoplastic resin.

  Specific examples of preferable thermoplastic resins include low density polyethylene, high density polyethylene, linear low density polyethylene, ultra-low density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-α-olefin copolymer, polypropylene, Ethylene-polypropylene copolymer, ethylene-butadiene copolymer, ethylene-carbon monoxide copolymer, ethylene-hexene copolymer, polybutene, butene-ethylene copolymer, butene-propylene copolymer, polystyrene, ethylene- Examples include vinyl acetate-carbon monoxide copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, and ethylene-methacrylic acid ester copolymer. As vinylidene chloride-based polymers, Vinylidene-vinyl chloride copolymer or diene polymer water Product can be exemplified. The above resin is not particularly limited in terms of melt flow rate, molecular weight, molecular weight distribution, catalyst used, production process and the like.

  Among these, an α-olefin (co) polymer and an α-olefin-vinyl ester copolymer when ethylene is included in the α-olefin are preferable from the viewpoints of elution controllability and film strength. Among the α-olefin (co) polymers, polyethylene is preferable, and low molecular weight polyethylene is more preferable in terms of biodegradability. When the coating material contains low molecular weight polyethylene, other alpha-olefin (co) polymers such as ethylene-1-octene copolymer or ethylene-vinyl acetate copolymer is used to compensate for the lack of physical strength of the coating. Use in combination with an α-olefin-vinyl ester copolymer such as a coalescence is preferred.

  A preferable coating solution used in the present invention is obtained by adding other coating materials to the poor solvent solution of the thermoplastic resin. The coating solution is particularly effective in a coating method in which the coating liquid is sprayed onto the particles and the organic solvent is instantly vaporized to form a coating. The resin used in the coating solution and the organic solvent which is a poor solvent are preferably a combination in which the resin is dissolved at a high concentration at a high temperature and the resin is precipitated at a low temperature to form a jelly. Since this combination forms a very dense film, it is particularly suitable for forming a time-eluting film.

  Other coating materials include talc, mica, cerite, glass flakes, various metal foils, graphite, BN (hexagonal crystal), MIO (plate iron oxide), plate carbon cal, plate aluminum hydroxide and other plates. Filler, calcium carbonate, silica, clay, various ore pulverized products, powdered inorganic filler such as sulfur, starch, oxidized starch, modified starch, cellulose, carboxy-modified cellulose, organic filler such as agar, surfactant, etc. Can be mentioned. The amount of the inorganic filler is preferably 3 to 90% by weight, and more preferably 20 to 80% by weight in the entire coating material. If it is this range, the fall of the physical strength of a film will also be few. The amount of the organic filler is preferably 40% by weight or less in the entire coating material. The organic filler may also be used as an elution rate modifier for the time elution type coated particles.

  The coefficient of variation of filler dispersion in the coating is preferably 50% or less, and more preferably 35% or less. When the coefficient of variation is 50% or less, variation in the elution function between the coated particles obtained tends to be small. The coefficient of variation is preferably closer to 0. However, when the coefficient of variation is less than 5%, the following coefficient of variation measurement method is difficult to measure due to a measurement error due to the shape of the filler. Is preferably 5 to 50%, more preferably 5 to 35%.

  The coefficient of variation of the filler dispersion in the coating is arbitrarily determined from the cutting surface of one particle coating, with the film thickness direction being vertical and the direction parallel to the film surface being transverse to the cutting surface of one particle coating. , Vertical × horizontal = 20 μm × 50 μm in 10 locations, 20 particles extracted arbitrarily were observed with a scanning electron microscope, the number of fillers present in each location was measured, and obtained from the measurement results (the coefficient of variation = Standard deviation / average value x 100).

Examples of the resin include nonionic surfactants typified by fatty acid esters of polyols, nonionic surfactants, cationic surfactants, anionic surfactants, and the like. The chain length, the number of added moles of alkylene oxide and the purity can be selected and used.
The amount of the surfactant is not particularly limited, but is preferably 0.01 to 15% by weight, more preferably 0.1 to 5% by weight based on the resin. These coating materials are dissolved, suspended, and dispersed in an organic solvent and sprayed from a spray nozzle.

  Further, various organometallic compounds may be used for the above resin in order to decompose the resin in the coating material. Examples of organometallic compounds include organometallic complexes and organic acid metal salts. Among these, iron complexes and iron carboxylates are preferable because the photodegradability can be easily adjusted. Examples of the iron complex include iron acetylacetonate, iron acetonylacetonate, iron dialkyldithiocarbamate, dithiophosphate, xanthate, and benzthiazole. Examples of the iron carboxylate include iron compounds such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, behenic acid, oleic acid, linoleic acid, and linolenic acid. These may be added alone or in combination of two or more. The ratio of the organometallic compound in the coating material is preferably 0.0001 to 1% by weight, more preferably 0.001 to 0.5% by weight. If it is said ratio, the desired disintegration or decomposability | degradability of a film will be obtained at the time of use of a coating particle, and the change of the quality of the coating particle during storage will be few.

  Although there is no restriction | limiting in particular in the organic solvent used by this invention, The thing which melt | dissolves a resin component and does not melt | dissolve particle | grains is preferable. Specifically, halogenated hydrocarbons such as tetrachloroethylene, dichloroethane and trichloroethane, aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane and heptane, ketones such as acetone and methyl ethyl ketone, acetic acid Examples include esters such as ethyl and butyl acetate.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited by these.
Example 1
Particle Coating Device The particle coating device used in Example 1 will be described with reference to FIG. The jet tower 1 has a tower diameter of 450 mm, a height of 6000 mm, an air outlet diameter of 100 mm, and a cone angle of 50 degrees, and has a core material (particle) inlet and a coated particle outlet. 2 is a spray nozzle, 3 is a core material (particle).
4 is a cyclone solid-gas separator having an inner diameter of 420 mm and a length of 1337 mm, and 5 is a multi-tube cooling condenser having an effective heat transfer area of 34.2 m ² . 6 is a root type blower of 1000 Nm ³ / h specification, and 7 is a fin tube type heater having an effective heat transfer area of 17.9 m ² . 8 is a coating material dissolution tank with a stirrer having a capacity of 130 L, which includes a heating steam jacket and a temperature controller. Reference numeral 9 denotes a diaphragm type coating liquid pump having a maximum liquid feeding amount of 100 L / h. 10 is a guide tube made of Teflon (registered trademark) having an inner diameter of 120 mm and a length of 660 mm, and 11 is a rectifying can.
A heat insulating material was wound around the conveyance path from the jet tower 1 and the outlet of the jet tower to the condenser 5 to keep the heat. In addition, pipes were wound around the solid-gas separator at intervals of 50 to 100 mm, water vapor of 0.2 MPa (gauge pressure) was passed, a steam trap was installed at the water vapor outlet, and a heat insulating material was wound from above to hold the heat. .

2. Production of coated particles Coated particles were produced by the following method using the particle coating apparatus. The blower 6 is started, and a heated gas of 100 ° C. heated by the heater 7 is blown from the lower part of the jet tower 1 to the upper part through the rectifier 11, and the solid-gas separator 4, condenser 5, blower is discharged from the outlet of the jet tower. 6, the apparatus was preheated by circulating for about 1 hour by the conveyance path connecting the heater 7 and the rectifier 11. Urea particles, which are core materials, were introduced into the jet tower 1 from the inlet provided on the side surface of the jet tower 1 to make the core material into a jet state. At this time, the flow rate and temperature of the hot gas were adjusted so that the particle (core material) temperature would be 70 ± 2 ° C. The flow rate was adjusted while measuring with a flow meter installed between the blower 6 and the flow rectifier 11, and the temperature was adjusted while measuring with the particle temperature or the jet tower outlet temperature.

On the other hand, polyethylene (low density polyethylene, density 0.923 g / cm ³ (JIS K 6760), melt flow rate (MFR) 0.3 g / 10 min (JIS K 6760)) 45 wt. Part, corn starch 5 parts by weight, talc (average particle size 10 μm) 50 parts by weight, ferric stearate 0.01 parts by weight and organic solvent tetrachloroethylene 1900 parts by weight, steam was passed through the steam jacket, and the liquid temperature 100 ± 2 The resin was dissolved by mixing and stirring at 1 ° C. for 1 hour to prepare a uniform coating material dissolution / suspension (coating solution) having a coating material component concentration of 5% by weight. The coating material dissolution tank 8 was constantly stirred until the coating operation was completed.

The coating liquid was transported at a flow rate of 180 kg / h to the spray nozzle 2 installed in the lower part of the jet tower, and sprayed onto the flowing core material to perform spray coating operation. In addition, the piping from the dissolution tank 8 to the spray nozzle 2 was made into a double structure so that the temperature of the coating liquid would not be 80 ° C. or less, and the coating liquid was transported while being heated through water vapor.
The coating operation starts when the temperature of the flowing core material reaches 70 ° C., and is performed until the coating amount reaches 12% of the final coated particles, and then the particle temperature is maintained at 70 ± 2 ° C. Only the heated gas was sprayed for 10 minutes to vaporize the organic solvent. After vaporization is completed, the coated particles are discharged from the outlet at the bottom of the flow straightening can, and after desolvation treatment with a gas not containing an organic solvent, the coated particles of the final product are obtained through a surface treatment that coats white carbon powder. It was.
From the second time, the same operation was repeated except that the preheating time was 10 minutes, and continuous batch production was performed 10 times. The yield of the coated particles was 66 kg each time. After the coated particles were cut, the core material was washed with water and the coating was dried, and the weight of the coating was measured, the coating amount with respect to the coated particles was 11.8% by weight each time. Met.

3. Film formation conditions One-fluid nozzle: outlet diameter 0.8 mm Full cone type core material: urea particles (particle size: 2.0 mm to 4.2 mm)
Core material input: 60kg
Particle (core material) temperature during coating: 70 ° C
Melting temperature: 100-110 ° C
Coating liquid temperature: 80-100 ° C
Gas temperature: 135-145 ° C
Gas flow rate: 450 Nm ³ / h
Spray flow rate: 180 kg / h
The circularity coefficient of the core material (value determined by the formula {(4π × projection area of particle) / (length of contour of particle projection) ² }) is calculated using IMAGE ANALYZER LUZEX-FS manufactured by NIRECO. It was measured. The measurement was performed using 100 particles taken out at random. The measurement result was 0.9945.

(Example 2)
Effective filtration area 2.5 m ² as a solid-gas separator in the apparatus of Example 1, inside diameter 202 mm, length 460 mm, dust collection efficiency 99.9% (when using JIS 7 standard powder; Kanto loam calcined dust, medium Using a bag filter equipped with 6 cartridge type filters (made of polyester) with a diameter of 30 μm and steamless piping, the solid-gas separator is wound around a water vapor pipe at intervals of 50 to 100 mm, 0.2 MPa (gauge Pressure) of steam, a steam trap was installed at the steam outlet, and a heat insulating material was wound from above to hold the heat. Others produced coated particles according to the apparatus and production method of Example 1. As a result of measuring the coating amount with respect to the coated particles according to Example 1, it was 11.8% by weight, and the yield of the coated particles was 66 kg each time.

(Example 3)
In the apparatus of Example 1, a solid-gas separator was directly connected in the order of the cyclone and the bag filter from the outlet of the jet tower, and the bag filter was kept warm by passing water vapor in the same manner as in Example 2. Others produced coated particles according to the apparatus and production method of Example 1. As a result of measuring the coating amount with respect to the coated particles according to Example 1, it was 11.8% by weight, and the yield of the coated particles was 66 kg each time.

Example 4
In the apparatus of the first embodiment, the apparatus is the same as that of the first embodiment except that the heat insulating material is wound around the conveyance path from the jet tower outlet to the solid gas separator, and the heat insulating material is removed from the conveyance path from the solid gas separator to the condenser. The coated particles were produced according to the production method. As a result of measuring the coating amount with respect to the coated particles according to Example 1, it was 11.8% by weight, and the yield of the coated particles was 66 kg each time.

(Comparative example)
In the apparatus of Example 1, coated particles were produced according to the production method of Example 1 in a state where the gas conveyance path and the jet tower did not have a heat retaining means. As a result of measuring the coating amount with respect to the coated particles according to Example 1, it was 11.7% by weight, and the yield of the coated particles was 66 kg each time.

4). Observation results of jet tower and solid-gas separator During operation in Examples 1 to 4, as a result of observing the inside of the jet tower from the viewing window, no condensation occurred in the jet tower, and a good operating state was maintained. We were able to.
After completion of the tenth operation, the solid-gas separator was opened and the state was observed. In Examples 1 to 4, no condensation was observed, and the separated solids could be collected in a dry state. When the bag filter was kept warm with water vapor, the differential pressure due to filtration loss was constant, and the dried state of the separated solid was better. Also, the temperature at the outlet of the jet tower was about 70 ° C., and the temperature at the condenser inlet was 58 ° C. by keeping the temperature. In Example 4, the temperature at the condenser inlet was from the solid-gas separator to the condenser. In the conveyance path, the temperature dropped to 50 ° C. due to the outside air temperature, and the load on the condenser could be reduced. The dew point of the gas was 46.8 ° C.
In the comparative example, as a result of observation from the spout tower observation window, dew condensation occurred in the spout tower from the middle of the eighth time. Therefore, the spray flow rate was reduced from 180 kg / h to 150 kg / h. The condenser inlet temperature at this time was 48 ° C. After completion of the eighth operation, the solid-gas separator was opened and the state was observed. The solid was wet. The differential pressure of the bag filter also increased, and the filter was backwashed with one or more jet pulses per operation, which seemed to be blocked.

5). Measurement of Elution of Coated Particles 10 g of coated particles (core material: urea) obtained in Examples 1 to 4 and Comparative Example and 200 ml of distilled water adjusted to 25 ° C. in advance are put into a 250 ml plastic container. And left in an incubator set at 25 ° C. Seven days later, all the water was extracted from the container, and the amount of urea contained in the extracted water (urea elution amount) was determined by quantitative analysis (dimethylaminobenzaldehyde method “detailed fertilizer analysis method second revised edition” Yokendo). The sample after draining water was put into a plastic bottle again, and 200 ml of distilled water was again put into the container and left in the same manner. This operation was repeated until the integrated value of urea elution amount reached 90%.
Thereafter, the coated particles were ground with a mortar, and the contents of the particles were dissolved in 200 ml of water, and then the urea remaining amount was quantitatively analyzed in the same manner as described above. The urea addition rate (elution rate) every 7 days was calculated by adding the total urea elution amount and the remaining amount of urea as the total amount of urea.
The coated particles obtained by the first, fifth, eighth and tenth productions were used.
As a result of the measurement, the coated particles obtained in Examples 1 to 4 had an elution rate of the urea component on the 7th day of the coated particles obtained in the 1st to 10th times of 0.5% or less, and 21 days. The elution rates of the eyes were all 1% or less. Moreover, the number of days for which the elution rate reaches 80% is stable as 98 to 103 days, indicating that coated particles with few defective particles can be stably produced continuously.

  In the coated particles obtained in the comparative example, the elution rate of the urea component on the 7th day was 0.5% for the first time, 4.2% for the 5th time, 11.6% for the 8th time, and the suppression effect was low. The gas separator tended to get worse gradually as it became obstructed. As the number of production increases, it becomes impossible to suppress elution, and it is difficult to obtain coated particles having quality stability and a time elution type elution function.

6). Red ink test In order to evaluate the elution performance of the coated particles of Examples 1 to 4 and Comparative Example, a red ink test was performed. Each of the obtained coated particles is accurately weighed and measured for the number of particles (X). After immersing these particles in a red ink liquid (350 g of Yokogawa's pen recorder ink G9620AN weighed sufficiently in 10 liters of distilled water) and allowing to stand at 23 ° C. for 2 hours, the particles were sufficiently removed with distilled water. To wash. Thereafter, the moisture on the surface of the particles is evaporated and dried, and the particles are sorted into a white product and a red product (including a part of the film stained). Count the number of red particles (Y). The number ratio of particles colored in red was calculated by the following formula.
Red colored particle number ratio (%) = Y / X × 100
It shows that there are few defects of a film, so that the number ratio of red colored particles is small.

  As a result, the percentages of red colored particles in Examples 1 to 4 were all 3% or less regardless of the number of productions, whereas the comparative examples were the same as the examples until the fourth production, It gradually increased and reached 10% at the 8th time. When the production sample of the 8th time of the comparative example was touched, the coating surface was fluffy and it seemed that many bubbles were contained. This is because the dry state is poor, and it seems that the film was dried with a lot of organic solvent. It peeled easily when a nail was stood on this film.

  The particle coating apparatus and the method for producing coated particles of the present invention can be suitably used for producing coated particles such as fertilizers, agricultural chemicals, pharmaceuticals, and foods.

The flow sheet which shows an example of the particle coating apparatus of this invention.

Explanation of symbols

1: Jet tower 2: Spray nozzle 3: Core material (particles)
4: Solid-gas separator 5: Condenser 6: Blower 7: Heater 8: Coating material dissolution tank 9: Coating liquid pump 10: Guide tube 11: Rectifier can 12: Organic solvent tank 13: Desolvation treatment equipment 14: Solvent recovery Apparatus 15: Surface treatment apparatus T1: Gas thermometer T2: Particle thermometer T3: Exhaust thermometer T4: Conveyance path thermometer F: Gas flow meter

Claims (6)

  A fluidized tank capable of keeping heat to cause the core particles to flow by supplying a high-temperature gas, spray a coating liquid composed of an organic solvent and a coating material on the core particles to vaporize the organic solvent, and form the coated particles. Including a heat-conveying path for discharging a gas containing an organic solvent from a fluidized tank, a solid-gas separator for separating a solid entrained in the gas containing the organic solvent, and an organic solvent after the solid is removed A particle coating apparatus comprising: a condenser for separating an organic solvent from a gas; and a blower for heating the gas after the organic solvent is removed and supplying the heated tank.   The particle coating apparatus according to claim 1, wherein the solid-gas separator can be kept warm.   The particle coating apparatus according to claim 1 or 2, wherein the heat source for heat insulation is water vapor.   The particle coating apparatus according to any one of claims 1 to 3, wherein the solid-gas separator is one or both of a cyclone and a bag filter.   The particle coating apparatus according to any one of claims 1 to 4, wherein the core material is fertilizer. The manufacturing method of the covering particle | grains using the particle | grain coating apparatus of any one of Claims 1-5.

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