JP2007216213A - Granulating method, granulated particle and granulating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a granulating method, a granulated particle and a granulating device which can form a discretional particle size distribution, support a wide variety of particle diameters, select a wide range of composition in a liquid material and improve productivity. <P>SOLUTION: The granulating method is a method for forming a particle from a liquid material by using a continuous ink-jet method, in which the liquid material containing a solid component and a binder component is supplied into one or more ink-jet nozzles of a continuous ink-jet device, a droplet is formed by ejecting the supplied liquid material from the ink-jet nozzle, the droplet is carried into drying means for drying the droplet, and the carried droplet is dried so as to obtain a granulated particle. The granulated particle and a granulating device are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a granulation method, a granulated product, and a granulation apparatus in which droplets are formed from a raw material liquid using a continuous ink jet method, and the droplets are dried and granulated.

  As one of granulation methods for producing particles such as powder and granules, a method is known in which a liquid containing a raw material is made into fine droplets, and these droplets are solidified by drying or the like. Conventionally, in order to produce a high-quality granulated powder, techniques relating to a method for forming droplets, a method for transforming formed droplets into particles, and the like have been studied.

  For example, as a granulation method by spray drying, in Patent Document 1, fine particles of a substance to be granulated are introduced into a chamber, and the granulated droplets are sprayed while being entrained in a dry kinetic gas flow. The technique of granulating by adding is disclosed. Patent Document 2 discloses a technique using a rotary atomizing disk (disk atomizer), in which a solid particle dispersion solution that continuously flows in a spray drying chamber is liquid-liquid using surface tension and centrifugal force of the disk. Techniques for generating droplets, drying and granulating are disclosed.

  Moreover, when granulating the raw material powder used for a powder metallurgy product, in patent document 3, a slurry is discharged | emitted by discharging a slurry from the oscillated porous nozzle, and this divided | segmented slurry is rapidly squeezed. A technique for obtaining a granulated powder having a controlled shape by drying it is disclosed. Patent Document 4 discloses a technique in which a slurry is dropped on a smooth and highly water-repellent dropping surface, and dried while being retained as spherical or deformed droplets by surface tension. Furthermore, Patent Document 5 discloses a technique for producing particles using an inkjet method, drying, and firing.

  The technology for producing granulated powder in this way is used in various fields such as powder metallurgy products, chemicals, cosmetics, and foods. And according to each use, a material, a particle size, a particle size distribution, etc. differ and the granulated powder of the desired quality is manufactured.

Japanese Patent Laid-Open No. 2001-070779 JP 2004-082005 A JP 2004-027313 A Japanese Patent Laid-Open No. 08-059352 JP 2005-137955 A

  Examples of quality indicators in powder materials include average particle size and particle size distribution, and it is desired to provide a high-quality granulated product in which the average particle size and particle size distribution are controlled with high accuracy. When the granulated product has a low uniformity of particle size and a wide particle size distribution, the following points are problematic. For example, when a raw material containing particles is processed using a tank or a hopper, a so-called shelving phenomenon or agglomeration may occur, and workability is often deteriorated. In addition, during processing, only coarse particles with good fluidity flow to the production line, while particles with small particle size with poor fluidity remain in tanks, and as a result, there is a possibility that the quality of the product may be uneven. . In particular, in the case where a process involving volume change such as firing and sintering is required after filling the mold, such as ferrite, dielectric, battery material, etc., the filling amount varies due to unevenness of the raw material powder. The variation in the filling amount causes distortion, cracks, vacancies, and variations in the characteristic values of the product after firing and sintering. And the following subjects are mentioned in prior arts, such as the above-mentioned patent documents 1-patent documents 5.

  When a granular material is produced by the granulation method of Patent Document 1, since the droplets are generated only by the surface tension of the continuously flowing granulation liquid, the particle size distribution tends to be widened. In addition, since the particle size is controlled by the nozzle diameter and the supply amount of the granulating liquid, the particle size can be controlled, but the particle size distribution may vary depending on the conditions. This is a problem in that the particle size distribution of the manufactured product becomes wider. In addition, the point that the granulated powder is drawn into a bag filter or the like is a problem in yield.

  In Patent Document 2, droplets are generated from a continuously flowing solid particle dispersion solution by using surface tension and centrifugal force of a disk, so that the particle size distribution becomes wide. Since the particle size distribution is controlled by the number of revolutions of the disk and the supply amount of the slurry, the control is difficult, and this is a problem in terms of yield together with the problem that the particle size distribution is widened. Further, since the granulated product having a relatively small particle size is drawn into the bag filter or the like simultaneously with the drying, the yield is further reduced.

  In the granulation method and the granulation apparatus of Patent Document 3, the particle size distribution tends to spread because the diameter of the porous nozzle is not always constant. Further, since the liquid is generated by dividing the slurry by vibrating the porous nozzle, the liquid droplets are generated at almost the same timing while the holes are close to each other even if the nozzle diameter is constant. The droplets coming out of the nozzles stick together, and the generation of deformed particles and the like is unavoidable, and the yield of monodisperse particles becomes a problem. Further, in order to instantly dry the droplets discharged from the porous nozzle, the discharge port of the porous nozzle must be adjacent to the mechanism for drying the droplets. As a result, the discharge port of the perforated nozzle is exposed to a dry state, and particularly when exposed to a dry state at a high temperature, the perforated nozzle portion may be deteriorated. Furthermore, since the porous nozzle itself vibrates for the generation of droplets, there is a possibility that physical and mechanical deterioration such as damage and wear of the porous nozzle due to vibration during use may occur. Deterioration of the multi-hole nozzle becomes a problem.

  In Patent Document 4, since droplets are dried by rolling the heated surface after the droplets are generated to obtain particles, deformation of the granulated particles becomes a problem. Moreover, the dropping surface used for the granulation method may cause a decrease in water repellency of the heating surface with use, and stable spherical particles may not be obtained. Furthermore, when granulating particles in large quantities, the amount of heat on the heated dropping surface may not satisfy the amount of heat necessary for granulation, which is a problem in terms of mass production.

  In Patent Document 5, an emulsion is used as the ink, and a piezo method, a thermal ink jet method, and a bubble jet (registered trademark) method are listed as the ink jet method. In the thermal ink jet method and the bubble jet (registered trademark) method, since the emulsion is ejected by the energy of bubbles when the liquid is vaporized by heating, the emulsion (ink) is given high heat, and the composition of the raw material liquid is affected. Therefore, there are restrictions on the types of granules that can be produced. In addition, the surface temperature of the heater used for heating to the extent that bubbles are generated becomes high, which places a burden on the heater, ink, ink head, and the like, and deterioration in the process of using these components becomes a problem. On the other hand, when the piezo method is used, the emulsion is discharged by the deformation of the piezo element to which voltage is applied, and a new emulsion is supplied to the nozzle part. Therefore, when the viscosity of the emulsion is high, the pressure required to supply the ink However, if the driving frequency of the piezo element is lowered and the response is reduced, the production amount is reduced, and it is difficult to form a desired droplet, and the yield becomes a problem. In addition, in a piezo-type ink jet device, the raw material liquid is always stored once in the ink reservoir in the ink jet nozzle, so depending on the components of the raw material liquid, if the flow of the raw material liquid stops even in a short time, the solids can settle and the nozzle can become clogged Sexuality increases. That is, there are many restrictions on the state of the raw material liquid used as a material, the contained components, the viscosity, and the like, and there is a problem that the range of the granulable composition and the particle diameter is narrow.

  In the present invention, an arbitrary particle size distribution can be formed, a wider range of particle sizes can be handled, the range of selection of the composition in the raw material liquid can be broadened, and the production efficiency can be improved. An object is to provide a granulation method, a granulated product, and a granulation apparatus.

  Therefore, as a result of intensive studies, the inventors of the present invention have adopted the following means in order to solve the above problems.

  The granulation method according to the present invention is a granulation method in which particles are formed from a raw material liquid using a continuous ink jet method, and the raw material liquid containing a solid content and a binder component is added to one or more of the continuous ink jet apparatus. The droplets are formed by discharging the supplied raw material liquid from the inkjet nozzles, and introducing the droplets into drying means for drying the droplets. It is characterized in that a granulated product is obtained by drying.

  Here, the granulated product is a powder, a granule or the like or a mixture thereof, for example, an inorganic material such as metal, metal oxide, metal hydroxide, metal carbonate, carbon black, silicon dioxide, edible powder, Examples include organic substances such as resins, and the like is not limited to a single substance, and may be a mixture of a plurality of types of granulated substances having different components. Moreover, solid content is a component which remains as solid content even if the granulated material is formed. Furthermore, examples of the binder component include PVA (polyvinyl alcohol), starch, agar, and various resins.

  In the continuous ink jet method (continuous ink jet method), a fluctuating pressure is applied to a liquid flow of ink or the like passing through a nozzle, and the liquid is separated from the liquid flow discharged from the nozzle in a state of receiving the fluctuating pressure. This is an ejection method characterized by the formation of, and is employed in, for example, a printer. In general, in the continuous ink jet method, a nozzle is provided with a piezo element, and a state of a liquid flow of ink or the like discharged from the nozzle is controlled by applying a voltage of a constant frequency to the piezo element. That is, when the liquid such as ink that flows out of the nozzle without interruption is passed through the nozzle, a fluctuating pressure corresponding to a predetermined frequency is applied by a piezoelectric element to which a voltage is applied. Due to this pressure fluctuation, immediately after the liquid such as ink is ejected from the nozzle, it is not separated into droplets but is in the form of a liquid flow and is affected by the pressure difference, and is a predetermined distance from the nozzle outlet. The shape changes to a droplet having a desired size at the position of. In the present invention, the above-described droplet forming method of the continuous ink jet method is applied to particle formation of a granulated product.

  In the granulation method according to the present invention, it is desirable to control the discharge state of the raw material liquid so that a desired droplet diameter is formed while monitoring the droplets discharged and formed from the inkjet nozzle. .

  In the granulation method according to the present invention, when the two or more inkjet nozzles are used, it is preferable to set an average droplet diameter of droplets formed from each inkjet nozzle for each nozzle.

  Furthermore, in the granulation method according to the present invention, when the two or more inkjet nozzles are used, it is preferable that the droplet components formed from each inkjet nozzle are changed for each nozzle to form droplets.

  And in the granulation method which concerns on this invention, it is preferable that the solid content of the said raw material liquid contains 1 or more components chosen from an inorganic substance or an organic substance. Here, examples of the state of the raw material liquid include slurry, suspension, aqueous solution, and emulsion.

  In the granulation method according to the present invention, the raw material liquid is preferably used after removing coarse particles with a filter of 500 mesh or more.

  In the granulation method according to the present invention, the raw material liquid is preferably used with a viscosity of 500 mPa · s or less. The viscosity was measured using a rotary viscometer under the condition of 62.5 rpm. Here, since the viscosity below the detection limit value for the raw material liquid is not reliable, a lower limit is not specified, and it is clearly stated that the upper limit is at least 500 mPa · s.

  In the granulation method according to the present invention, it is preferable to use a thickener added to the raw material liquid.

  Furthermore, in the granulation method according to the present invention, it is preferable to select and use a nozzle diameter of the inkjet nozzle in the range of 20 μm to 120 μm depending on the particle diameter of the particles to be formed.

  In the granulation method according to the present invention, the raw material liquid is discharged from the ink jet nozzle continuously by supplying the raw material liquid into the ink jet nozzle at a constant speed and discharging the raw material liquid at a constant speed by the supply raw material liquid pressure. In addition, it is preferable to apply a pressure fluctuation to the raw material liquid flow passing through the ink jet nozzle.

  In the granulation method according to the present invention, the pressure fluctuation applied to the raw material liquid flow is preferably performed by using a piezo element and changing the pressure by controlling the voltage applied to the piezo element.

  And the granulated material of this invention is manufactured using the granulation method in any one of said, The average particle diameter is 5 micrometers-500 micrometers, It is characterized by the above-mentioned. The average particle diameter here is obtained by measuring the ferret diameter of a granulated product photographed with an SEM (scanning electron microscope) and calculating the number average particle diameter from the measurement result.

  Moreover, the granulation apparatus according to the present invention is a granulation apparatus for performing the granulation method according to any one of the above, wherein a liquid storage unit, a discharge unit, a drying unit, and a collection unit are connected in series. The raw material liquid arranged and stored in the liquid storage part is continuously supplied to one or more ink jet nozzles provided in the discharge part, and the raw material liquid in the ink jet nozzle is inkjetted by a continuous ink jet device provided in the discharge part. The droplets are ejected from the nozzle to form droplets, and the droplets are introduced into the drying unit, and the introduced droplets are dried in the drying unit to form a granulated product, and the granulated product is collected in the collecting unit. It is characterized by that.

  And in the granulation apparatus of this invention, it is preferable to select and use the nozzle diameter of the said inkjet nozzle of the range of 20 micrometers-120 micrometers according to the particle diameter of the particle | grains to form.

  Moreover, in the granulation apparatus of this invention, the discharge state of a raw material liquid is controlled with the said continuous-type inkjet apparatus so that the average particle diameter of the granulated material manufactured may become a desired average particle diameter between 5 micrometers-500 micrometers. It is preferable.

  Further, the granulating apparatus of the present invention is provided with a measuring means for measuring the droplet diameter of the formed droplet, and the raw material liquid is discharged so as to have a predetermined droplet diameter according to the measurement result by the measuring means. It is preferable to control the state.

  And in the granulation apparatus of this invention, when using the said 2 or more inkjet nozzle, the said continuous inkjet apparatus discharges a raw material liquid according to the shape and / or component of the droplet which should be formed for every inkjet nozzle. It is preferable to control the state.

  Furthermore, in the granulating apparatus of the present invention, the liquid storage part is equipped with a stirring mechanism that stirs the raw material liquid and maintains the mixed state, and the solid content contained in the raw material liquid is uniformly dispersed in the raw material liquid by the stirring mechanism. Is preferably maintained. Here, the mixed raw material liquid is a state in which the components of the raw material liquid are mixed without being biased by precipitation or the like.

Granulation method: The granulation method according to the present invention is a granulation method in which particles are formed from a raw material liquid using a continuous ink jet method, and a raw material liquid containing a solid content and a binder component is removed from a continuous ink jet apparatus. Since droplets are formed by supplying into one or two or more inkjet nozzles and discharging the supplied raw material liquid from the inkjet nozzles, the size of the droplets formed by using the continuous inkjet method It is possible to accurately adjust the size to a desired size, and to adjust the droplet diameter before drying. And since the said droplet is introduce | transduced in the drying means which dries a droplet and the introduced droplet is dried and a granulated material is obtained, the granulated material with a sharp particle size distribution can be manufactured. Therefore, the granulated product produced by the granulation method according to the present invention is aligned with a desired average particle size and can have a desired particle size distribution, so that it is effective for maintaining a high quality product, It is possible to omit steps such as classification in the subsequent steps, which is also effective in terms of manufacturing costs.

  Further, for example, in a piezo-type ink jet device, a raw material liquid (ink, etc.) is always accumulated once in an ink reservoir in an ink jet nozzle. Therefore, depending on the composition of the raw material liquid, if the flow of the raw material liquid stops even in a short time, the solid content is reduced. Although the possibility of settling and clogging of the nozzle increases, in the continuous ink jet method, the raw material liquid applied in a state where the pressure fluctuates forms droplets after being continuously discharged from the nozzle. Therefore, compared to other ink jet methods, there are few restrictions on the relationship between the raw material liquid and the discharge state from the nozzle, and it is possible to have a wide range of choices such as the nozzle diameter, the solid content of the raw material liquid, the viscosity, A wide variety of granulated products can be produced. In addition, by using the continuous ink jet method, the timing of forming droplets from the raw material liquid can be controlled, so that the formed droplets can be discharged at a timing that does not stick to each other. Generation of granulated material can be suppressed. Therefore, the granulated product can be produced with a high yield, and it is not necessary to perform a step for adjusting the particle size of the granulated product, such as classification, so that the production efficiency is good and the granulation can be performed economically. In addition, as described above, it is possible to obtain a granulated product having a uniform particle size by forming droplets by ink jet and granulating, but it is desirable to monitor the droplet size of the formed droplets as desired. By controlling the discharge state of the raw material liquid so that the droplet diameter is formed, the particle diameter of the granulated product can be granulated with higher accuracy.

Granulated product: The granulated product according to the present invention is granulated using the above granulation method, and has an average particle size of 5 μm to 500 μm. Therefore, the granulated product is produced from a raw material liquid containing a solid content and a binder component. The granules correspond to a wide range of particle sizes and become a granulated product having a sharp particle size distribution. In particular, a granulated product having a sharp particle size distribution can be obtained even with a small particle size.

  Furthermore, when the ejection function is controlled for each inkjet nozzle in accordance with the shape and / or component of the droplet to be formed, a granulated product corresponding to an arbitrary particle size distribution or a granulated product composed of a mixture is obtained.

Granulation apparatus: The granulation apparatus according to the present invention is a granulation apparatus for performing the granulation method described above, wherein a liquid storage unit, a discharge unit, a drying unit, and a collection unit are arranged in series, The raw material liquid stored in the liquid storage part is continuously supplied to one or more ink jet nozzles provided in the discharge part, and the raw material liquid in the ink jet nozzle is discharged from the ink jet nozzles by a continuous ink jet device provided in the discharge part. The droplets thus formed are introduced into the drying unit, and the introduced droplets are dried in the drying unit to become a granulated product, and the granulated product is collected in the collecting unit. The droplets can be precisely sized before drying, and granulated powder having a sharp particle size distribution can be easily produced.

  In addition, by controlling the droplet diameter of the droplets formed from each inkjet nozzle for each nozzle, the particle size of the resulting granulated product can be controlled, so that not only high yield but also classification etc. Since it is not necessary to perform a step for adjusting the particle size of the granulated product, it can be granulated with high production efficiency and economically. In addition, even when classification is performed, the generation of non-standard products is small, so that the amount of waste can be reduced, which is economical and environmentally friendly. Then, a measuring means for measuring the droplet diameter of the formed droplet is provided, and if the discharge state of the raw material liquid is controlled so as to obtain a predetermined droplet diameter in accordance with the measurement result by the measuring means, it can be manufactured with higher accuracy. Granules can be aligned to a desired particle size.

  Further, when two or more inkjet nozzles are used, if the ejection function is controlled for each inkjet nozzle according to the shape and / or component of an arbitrary droplet, a desired blending ratio or Granulated products having a particle size distribution can be produced in a batch. For example, in the case of a powder in which a high filling rate is desired by filling a gap between substances having a large particle size with a material having a small particle size, a state in which powders having different particle sizes are mixed is preferable. Even if it is not sharp, it is desired that the powder has an appropriate particle size distribution. Therefore, for example, a granulated product having a normal particle size distribution and a granulated product having a particle size distribution having a plurality of peaks can be manufactured in a lump. A granulated product can be produced easily and efficiently without the need for classification according to the distribution or blending of powders having different particle diameters.

  Hereinafter, the best embodiment of the granulation method, the granulated product, and the granulation apparatus according to the present invention will be described.

[Granulation method]
The granulation method according to the present invention is a granulation method in which particles are formed from a raw material liquid using a continuous ink jet method, and includes the following steps.
Step 1: A raw material liquid containing a solid content and a binder component is supplied into one or two or more ink jet nozzles of a continuous ink jet apparatus, and droplets are formed by discharging the supplied raw material liquid from the ink jet nozzle. To do.
Step 2: The droplets are introduced into a drying means for drying the droplets.
Step 3: Particles are formed by drying the introduced droplets.
Step 4: Collect the formed particles.
Hereinafter, it demonstrates for every process.

  Step 1: In Step 1, a raw material liquid containing a solid content and a binder component is supplied into one or two or more ink jet nozzles of a continuous ink jet apparatus, and the supplied raw material liquid is discharged from the ink jet nozzle. Form droplets.

  The raw material liquid includes a solid content and a binder component, and the solid content includes one or more components selected from an inorganic material or an organic material. Examples of inorganic substances include metals, metal oxides, metal hydroxides, metal carbonates, carbon black, silicon dioxide, and the like. Moreover, as an organic substance, edible powder, resin, etc. are mentioned. Examples of the binder component include PVA, starch, agar, and various resins. And as a state of a raw material liquid, the emulsion etc. which disperse | distributed hydrophobic substances, such as a slurry, suspension, aqueous solution, and resin, to water are mentioned, for example. The raw material liquid is supplied into the ink jet nozzle in a mixed state.

  Moreover, when coarse particles are removed with a filter of 500 mesh or more and the raw material liquid is used, clogging of the inkjet nozzles due to coarse particles can be prevented. Here, with a filter of less than 500 mesh, coarse particles having a size that easily clogs the inkjet nozzle cannot be removed. And it is more preferable to use it by removing coarse particles using a filter of 600 mesh or more.

  Moreover, it is preferable that the viscosity of this raw material liquid is 500 mPa * s or less. When the viscosity of the raw material liquid exceeds 500 mPa · s, the viscosity is too high and the raw material liquid is difficult to be discharged from the inkjet nozzle. Then, the nozzle diameter of the inkjet nozzle and the pressure applied to the raw material liquid are adjusted according to the viscosity of the raw material liquid.

  Furthermore, it is preferable to add a thickener to the raw material liquid. By adding a thickener in a range where the viscosity of the raw material liquid does not exceed 500 mPa · s, sedimentation of the solid content can be prevented and the dispersibility of the raw material liquid (slurry or the like) can be stabilized. In particular, when granulating a small particle size, it is necessary to reduce the nozzle diameter or reduce the solid content. In this case, since the viscosity of the raw material liquid tends to be low, it can be adjusted to a suitable viscosity with a thickener, and the dispersibility of the raw material liquid can be made more stable. Moreover, when there is little solid content in a raw material liquid, the dispersibility of a raw material liquid can be made uniform and it is preferable from the point from which the granulated material with stable quality is obtained. Furthermore, when the solid content having a large specific gravity is contained in the raw material liquid, the thickener can effectively disperse the solid content. As the thickener, acrylic acid polymer, starch, xanthan gum, polyethylene glycol distearate and the like can be used.

  The continuous ink jet apparatus includes a piezo element (piezoelectric element) as means for controlling the discharge state of the raw material liquid discharged from the ink jet nozzle. The expansion of the piezo element changes according to the applied voltage. Using this property of the piezo element, when the drive frequency of the piezo element is controlled by applying a voltage of a predetermined frequency to the piezo element, the raw material liquid supplied into the ink jet nozzle is changed according to the expansion change of the piezo element. The pressure of this is fluctuated. As a result, the raw material liquid is discharged from the inkjet nozzle in a state where it is easily separated as droplets at a constant interval while being in an uninterrupted state. Thereafter, droplets are formed by separating from the liquid flow.

  That is, the raw material liquid continuously supplied into the ink jet nozzle at a constant speed is continuously discharged at a constant speed by the supply raw material liquid pressure. At this time, by applying a pressure fluctuation to the raw material liquid flow passing through the ink jet nozzle before discharging from the nozzle, droplets are formed by separating from the raw material liquid flow after discharging, resulting in a predetermined result. A droplet of a predetermined size is formed at a speed.

  In the above-described continuous ink jet method, the raw material liquid can be separated as droplets at a desired timing by adjusting the strength of the pressure applied to the raw material liquid discharged from the ink jet nozzle. Therefore, if the nozzle diameter of the inkjet nozzle, the voltage applied to the piezo element and the frequency thereof are controlled according to the nozzle diameter, the raw material liquid is ejected so as to be separated into droplets of a desired size, and the droplet diameter Can be formed.

  Here, the size of the formed droplet is controlled by the viscosity of the raw material liquid, the nozzle diameter, and the driving frequency of the piezo element. Furthermore, the upper limit drive frequency of the piezo element is calculated based on the nozzle diameter and ejection speed of the inkjet nozzle, and can be in a range of approximately 5 KHz to 720 KHz, and can increase the amount of droplet formation per unit time. is there. Further, in the case of the continuous ink jet method, the nozzle diameter of the ink jet nozzle is less restricted than in the piezo method in which droplets are formed at the discharge stage, and a wider range of nozzle diameters can be used. Further, since the raw material liquid flows without remaining from the liquid storage part to the nozzle, the solid content contained in the raw material liquid is less likely to clog the nozzle, and the range of selection of the composition of the raw material liquid can be widened.

  In addition, the nozzle diameter of an inkjet nozzle is set in the range of 20 micrometers-120 micrometers according to the particle size of the granulated material which should be granulated. If the nozzle diameter of the inkjet nozzle is less than 20 μm, the raw material liquid containing a solid content is difficult to be discharged because it is too small, and is not suitable for practical use. On the other hand, when the nozzle diameter of the inkjet nozzle is larger than 120 μm, the discharge amount increases, and as a result, the droplets become large, and it is difficult to dry while maintaining the preferred shape even when introduced into the next drying means. It becomes difficult.

  Moreover, the discharge speed at the time of discharging a raw material liquid from an inkjet nozzle is adjusted according to a raw material liquid so that it may become a predetermined speed. That is, by adjusting the nozzle diameter of the ink jet nozzle, the viscosity of the raw material liquid, and the supply speed of the raw material liquid supplied into the ink jet nozzle, adjustment is made so that the raw material liquid is discharged at a constant speed.

  Moreover, if the discharge state of the raw material liquid is controlled so that a desired droplet diameter is formed while monitoring the formed droplets, a high-quality granulated product with a more uniform particle diameter can be produced. be able to. That is, even if the continuous ink jet method is used, it is considered that the particle size of the granulated product may slightly vary due to changes in the properties of the raw material liquid such as fine solid content and viscosity of the raw material liquid. In order to cope with this variation and keep the droplet diameter constant with higher accuracy, it is effective to optimize the droplet formation conditions while monitoring the formed droplet diameter. In addition, it is possible to detect an abnormality of a droplet accompanying a defect or the like that occurs during manufacturing at an early stage, and manufacturing loss can be suppressed. As an example of the monitoring method, an example in which a CCD camera or the like is arranged on the ejection port side of the inkjet nozzle can be given.

  Here, considering the production capacity of droplets, the continuous inkjet system has a small production capacity per inkjet nozzle, but if a plurality of inkjet nozzles are provided, the productivity problem can be solved. In addition, when forming droplets using two or more inkjet nozzles, it is possible not only to increase the production amount by forming a single particle size with a plurality of inkjet nozzles, but also Since the particle diameter can be made uniform, it is possible to improve the yield of the granulated product with uniform quality.

  On the other hand, it is also possible to control the ejection state for each inkjet nozzle so as to form droplets by changing the component and / or shape of the droplets ejected from each inkjet nozzle for each nozzle. In this case, for each inkjet nozzle, if the discharge state is controlled by changing the droplet formation conditions such as the nozzle diameter, the voltage applied to the piezo element, the drive frequency of the piezo element, etc., a granulated product that forms an arbitrary particle size distribution Can be manufactured all together or a mixture can be manufactured all at once, and the step of mixing granulated powders having different components and / or shapes can be omitted.

Step 2: The droplets are introduced into a drying means for drying the droplets. Here, since the discharge direction of the droplets formed by being discharged from the inkjet nozzle is stable, the droplets can be accurately introduced into the drying means from the inkjet nozzle.

Step 3: Granulate by drying the introduced droplets. In other words, the drying means can dry the droplets to the extent that they can be transformed into a granulated product, and can include, for example, an airflow generation means for stirring the atmosphere in a container such as a drying chamber. The droplets introduced into the drying means are dried by an air current, a dry gas, temperature, etc., and changed into a granulated product.

Step 4: Collect the granulated product granulated in Step 3 in the collection part. For example, the granulated material collected using collection means, such as a cyclone classifier, is accommodated in a container.

[Granulated product]
The granulated product according to the present invention is granulated using the granulation method described above. Using the above granulation method, by controlling the drive mechanism of the ink jet nozzle according to any condition of the granulated product, such as particle size and particle size distribution, it is dried after forming droplets of any size And granulate. The granulated product thus produced becomes a granulated product having a sharp particle size distribution regardless of the particle size. This granulated product is averaged by adjusting the characteristics of the raw material liquid, such as solid content, viscosity, solid content particle size, and the inkjet nozzle diameter, and controlling the voltage applied to the piezoelectric element and the driving frequency of the piezoelectric element. Granules having an arbitrary size between 5 μm and 500 μm are produced. That is, since there are many factors that control the droplets to be formed, it is possible to produce a granulated product with a wide particle size while maintaining a sharp particle size distribution. It is possible to obtain a suitable particle size distribution. In order to obtain a high-quality granulated product with reduced particle size variation, the average particle size of the granulated product is more preferably 15 μm to 500 μm, and even more preferably a desired average particle size between 20 μm and 400 μm. It is preferable to control so that.

[Granulation device]
In the granulating apparatus according to the present invention, a liquid storage unit, a discharge unit, a drying unit, and a collection unit are arranged in series.

  The liquid storage part stores the raw material liquid in order to send the adjusted raw material liquid to the discharge part, and is piped so that the raw material liquid is transmitted from the liquid storage part to the discharge part described later. The liquid storage unit includes a container that can store the raw material liquid and can be sealed, and a stirring mechanism that stirs the raw material liquid and maintains a mixed state. The solid content contained in the raw material liquid is contained in the raw material liquid by the stirring mechanism. Those that are dispersed and kept in a mixed state are preferred. Thereby, precipitation of the solid content contained in a raw material liquid can be prevented, and the droplet without a spot in a component can be formed smoothly. Moreover, it can prevent that the raw material liquid with many solid content clogs in an inkjet nozzle.

  Here, the raw material liquid put into the liquid storage part is preferably obtained by removing coarse particles with a filter of 500 mesh or more in advance. Therefore, the coarse particles removed by a filter in advance may be supplied to the liquid storage part, but the above-mentioned filter may be provided at the inlet for introducing the raw material liquid into the liquid storage part.

  Further, the liquid storage unit connected to the ink jet nozzle so as to be able to supply the raw material liquid is pressurized, and the raw material liquid is automatically supplied into the ink jet nozzle according to the decrease amount of the raw material liquid discharged from the ink jet nozzle. In this case, the supply speed of the raw material liquid into the ink jet nozzle is synchronized with the discharge speed of the raw material liquid, and the raw material liquid injection means such as a pump becomes unnecessary.

  In addition, when two or more inkjet nozzles are provided and it is desired to manufacture a mixture of substances having different components, a configuration in which a plurality of liquid storage units are provided and each liquid storage unit is connected to each inkjet nozzle is provided. good.

  The discharge unit includes an inkjet device. An ink jet apparatus includes one or more ink jet nozzles, a piezo element (piezoelectric element) for controlling a discharge state of a raw material liquid discharged from the ink jet nozzle, and an ink jet nozzle drive mechanism for applying a voltage to the piezo element. And. The ink jet nozzle is continuously provided so that the raw material liquid can be supplied from the liquid storage section. The nozzle diameter of this inkjet nozzle is selected and used within the range of 20 μm to 120 μm depending on the particle size or particle size distribution of the granulated product to be granulated. And the discharge state of a raw material liquid is controlled with a continuous inkjet apparatus so that the average particle diameter of a granulated material may become a desired average particle diameter between 5 micrometers-500 micrometers. That is, when a voltage of a predetermined frequency is applied to the piezo element by the control of the ink jet nozzle drive mechanism, the expansion of the piezo element changes according to the drive frequency, and the pressure on the raw material liquid supplied into the ink jet nozzle is changed. fluctuate. As a result, the raw material liquid is discharged from the inkjet nozzle without being separated although it is in a state where it can be easily separated as droplets at regular intervals.

  If the piezo element does not have a mechanism for cooling the element itself, the piezo element cannot withstand high heat, and therefore, the discharge unit is disposed outside the drying unit. However, for example, when the drying unit adopts drying at a temperature that the piezo element can withstand, such as room temperature drying, or in the case of a discharge unit with a piezo element equipped with a cooling mechanism, the discharge unit is arranged in the drying unit You may do it. Since the ink jet nozzle can easily determine the discharge direction, even if the discharge part is arranged outside the drying part, the droplets formed by being discharged from the ink jet nozzle are provided in the drying part described later. By disposing the discharge unit and the drying unit so as to have a positional relationship that progresses toward the front, droplets can be accurately introduced from the inkjet nozzle toward the opening.

  Here, if the liquid droplet is formed by applying a deflection voltage so that the liquid droplet discharged from the ink jet nozzle and separated from the raw material liquid flow proceeds in a predetermined direction, the liquid can be easily obtained. The traveling direction of the droplet can be adjusted, and the droplet can be more reliably introduced into the drying unit. Therefore, the installation position of the drying unit is not limited to the position immediately below the discharge unit, and even when the drying unit is disposed below, fine adjustment of the nozzle and the drying unit can be performed by the deflection voltage. In addition, when the droplets are not put into the drying section, if the deflection voltage is applied to the droplets so that they enter the droplet recovery container, the raw material liquid collected in the recovery container can be reused. There is no waste.

  In a conventional granulation method such as a disk atomizer method, a droplet forming device is provided with a discharge port in an environment of heat or a dry state inside a drying mechanism, but in the granulation method according to the present invention, In addition, since there is no need to dispose the ink jet nozzle for forming the droplets in the drying section, the ink jet apparatus is hardly affected by heat and drying, and can be an apparatus that is less likely to deteriorate with use. In addition, since the ink jet device can be installed outside the drying device, when the continuous ink jet device is inspected or repaired, the operation of only the ink jet nozzle portion can be stopped, so that the droplets can be removed in the drying section. It is not necessary to stop the drying process, and a decrease in productivity can be suppressed as much as possible.

  Furthermore, a measuring means for measuring the droplet diameter of the formed droplets is provided, and a means for controlling the discharge state of the raw material liquid so as to obtain a predetermined droplet diameter according to the measurement result by the measuring means. In this case, the droplet diameter can be controlled with higher accuracy. For example, a CCD camera or the like can be used for the measurement. A CCD camera is arranged on the side of the ejection port of the inkjet nozzle, and the image is measured by photographing with the CCD camera using a strobe synchronized with the drive frequency of the piezo element of the inkjet nozzle. If the measurement result deviates from the desired droplet diameter, control is performed so that the desired droplet diameter is obtained by controlling the inkjet nozzle drive mechanism. In this way, if the discharge state of the inkjet nozzle is controlled so as to obtain a desired droplet diameter while measuring and monitoring the formed droplet diameter, it becomes possible to align the droplet diameter with higher accuracy. As a result, the particle size of the granulated product can be aligned with high accuracy.

  The drying unit may be provided with a means for keeping the container main body containing the droplets in a dry state that can transform the droplets into a granulated product, an airflow generating means for stirring the atmosphere in the container, and the like. As a result, it is only necessary to have a mechanism for transforming the introduced droplets into a granulated product while maintaining the shape in the drying section.

  The collection unit is a mechanism for collecting the granulated product dried in the drying unit, for example, a collection unit such as a cyclone classifier, and a collection container for storing the granulated product collected by the collection unit. And. Then, for example, the granulated material is collected by a method such as suctioning the granulated material in the drying unit. At this time, a decrease in yield can be prevented by appropriately setting the pressure difference between the inside and outside of the collection part.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

Granulating apparatus: FIG. 1 is a schematic view of a granulating apparatus in an embodiment according to the present invention. As shown in FIG. 1, the granulating apparatus in Example 1 includes a liquid storage part (pressure vessel 1, stirrer 2, magnetic stirrer 3) and a discharge part (inkjet nozzle part 4, AC generator for driving an ink jet nozzle). 5), drying unit (drying chamber 6, drying mechanism 7), collection unit (cyclone 8, granule collection container 9) for collecting the granulated product, and fine powder of the granulated product The bag filter 10 for collecting the body and the fine powder collecting container 11 were used.

  The liquid storage part includes a container (pressure vessel 1) that can store a raw material liquid and can be sealed, and a magnetic stirrer 3 as a stirring mechanism, and the container (pressure vessel 1) is disposed on the magnetic stirrer 3 did. And the stirring bar 2 was put into the container with the raw material liquid. In addition, although the example which provided the 1 liquid storage part was shown in the present Example, when equipped with two or more inkjet nozzles and wants to manufacture the mixture which consists of a substance of a different component, it equipped with several liquid storage parts, It is good also as a structure by which the liquid storage part was continuously provided corresponding to each inkjet nozzle.

  The discharge unit includes an inkjet nozzle unit 4 including a plurality of inkjet nozzles (not shown) and an inkjet nozzle driving AC generator 5 that controls the driving conditions of the inkjet nozzles. Each inkjet nozzle unit 4 includes a piezo element (not shown), and the expansion state of the piezo element is changed by applying a voltage of a constant frequency from the inkjet nozzle driving AC generator 5 to the piezo element. The raw material liquid supplied from the liquid storage part continuously flows in the inkjet nozzle. When this raw material liquid flow passes through the nozzle, the pressure of the predetermined period is applied to the raw material liquid flow due to the change in the extension state of the piezoelectric element. As a result, pressure fluctuations are applied to the raw material liquid flow, and the raw material liquid is discharged in a state of separating into droplets of a set size while proceeding in the discharge direction without interruption.

  As a measuring means for measuring the droplet diameter of the formed droplet, a CCD camera is disposed on the side of the ejection port of the inkjet nozzle, and a strobe synchronized with the driving frequency of the piezo element of the inkjet nozzle is used. The measurement was taken with a CCD camera. If a means for controlling the discharge state of the raw material liquid so as to obtain a predetermined droplet diameter according to the measurement result by the measuring means is provided, the droplet diameter can be controlled with higher accuracy. If the measurement result deviates from the desired droplet diameter, the ink jet nozzle drive mechanism adjusts the conditions such as the discharge speed of the raw material liquid, the applied voltage to the raw material liquid, the drive frequency of the piezo element, and the desired droplet diameter. Controlled to be.

  The drying unit is an air flow drying device having a height of 2 m, and this air flow drying device is provided with an opening (not shown) that opens in the traveling direction of the raw material liquid discharged from the inkjet nozzle, and is introduced from this opening. The droplets are dried in an environment in which the drying temperature and the air volume are controlled to form a granulated product.

  The collection unit includes a cyclone 8 and a granule collection container 9 that accommodates the granule taken out by the cyclone 8, and the granule is conveyed by the airflow flowing in the direction of arrow P. The configuration is as follows. Further, in order to perform more strict quality control and to keep industrial safety, small granulated materials that could not be collected by the cyclone 8 are connected to a fine powder collecting device (bug filter 10). ) And collected in a fine powder collection container 11.

Granulation method using a granulator: Next, using the above granulator, granulation is performed using a case where an Mn-Mg-Sr ferrite precursor is produced so that the average particle diameter is 100 μm. The grain method will be described. First, a raw material liquid was prepared. 25 liters of water is put into a bead mill having a capacity of 40 liters, and then, as raw materials, 15.53 kg of iron (III) oxide, 8.90 kg of manganese trioxide, 0.57 kg of magnesium hydroxide, and 0.72 kg of strontium carbonate are added. I put it in. In addition, 250 g of PVA having a solid content of 10 wt% was added as a binder component. Furthermore, as a dispersant, 275 g of a special polycarboxylic acid polymer surfactant having a solid content of 60 wt% was added, pulverized and mixed for 2 hours, and the prepared slurry was filtered through a 635 mesh stainless steel net to remove coarse particles. A raw material solution was prepared. The raw material liquid has a solid content of 50 wt% and a viscosity of 100 mPa · s.

  Subsequently, the raw material liquid and the stirring bar 2 for the magnetic stirrer 3 were placed in the pressure vessel 1 and sealed, and then pressurized by feeding compressed air into the pressure vessel 1. In the raw material liquid in which the stirrer 2 was enclosed, the stirrer 2 was rotated by the magnetic stirrer 3 so that the raw material liquid was constantly stirred and the mixed state in which the solid content was dispersed in the raw material liquid was maintained.

  Here, the average particle diameter of the granulated material to be manufactured was set to 100 μm, and the nozzle diameter of the inkjet nozzle was set to 60 μm according to conditions such as the viscosity of the raw material liquid. In addition, a sine wave AC voltage having a frequency of 70 KHz and an amplitude of 5 V was applied from the inkjet nozzle driving AC generator to the piezoelectric element.

  The raw material liquid in a mixed state is supplied into the inkjet nozzle of the discharge unit, and the raw material liquid is supplied with a fluctuating pressure from a piezo element to which a sine wave AC voltage having a frequency of 70 KHz and an amplitude of 5 V is applied. Discharge. As a result, when the raw material liquid is discharged from the discharge portion of the inkjet nozzle, it is discharged in a state where the raw material liquid is separated into droplets at a constant interval while being continuous.

  At this time, the pressure to the supplied raw material liquid was adjusted in the liquid storage section so that the raw material liquid was discharged at a constant speed of 10 m / s. Note that, as described above, the ejection speed of the liquid droplets was measured by photographing using a strobe synchronized with the driving frequency of the piezo element of the ink jet nozzle by a CCD camera disposed on the side of the ejection port of the ink jet nozzle.

The droplets formed from the raw material liquid discharged from the discharge port of the inkjet nozzle were then guided in a form that was blown at a constant speed toward the opening of the drying unit, and were introduced into the drying unit from the opening. . As described above, the continuous ink jet apparatus can control the traveling direction of the liquid droplets ejected from the nozzles, so that the liquid droplets can be accurately introduced into the openings. The droplets thus introduced into the drying section are dried in an environment with a drying temperature of 300 ° C. and an air volume of 4 m ³ / min to become a granulated product.

  Particles granulated by drying in the drying section were collected in a granulated material collection container 9 using a cyclone 8 installed at a hot air outlet. Further, the fine powder that could not be collected by the cyclone 8 was collected using a fine powder collecting device (bug filter 10) and collected in the fine powder collecting container 11. As a result, most of the granulated material was collected in the granulated material collection container 9, and almost no granulated material was collected in the fine powder collection container 11.

  The ferrite precursor (granulated material) collected in the granulated material collection container 9 in Example 1 was photographed with SEM, and the ferret diameter of 100 ferrite precursors (granulated materials) was measured. The average particle diameter (number average particle diameter) D and standard deviation σ were calculated from the measured ferret diameter of the dried product, and the CV value was calculated as standard deviation σ / average particle diameter D. As a result, the average particle diameter of the ferrite precursor (granulated material) was D = 99.7 μm, the standard deviation of the particle diameter was σ = 12.5 μm, and the CV value was (σ / D) = 0.13. The particle size distribution diagram of the obtained ferrite precursor (granulated product) is shown in FIG.

Granulation apparatus: The granulation apparatus of Example 2 differs from Example 1 in that a plurality of inkjet nozzles having different nozzle diameters are provided in the discharge part, and the configuration other than the discharge part is the same as in Example 1. is there. Therefore, description of a liquid storage part, a drying part, and a collection part is omitted.

  The inkjet nozzle part 4 provided in the discharge part is configured to have a nozzle diameter of 60 μm and a nozzle diameter of 40 μm at the same ratio. The method of discharging the raw material liquid discharged from the ink jet nozzle is the same as that of the first embodiment, but the size of the formed droplet is controlled by the viscosity of the raw material liquid, the nozzle diameter, and the driving frequency of the piezo element. Differences occur due to differences in diameter.

Granulation method using a granulator: Next, using the above granulator, a method for producing the same Mn—Mg—Sr ferrite precursor (granulated product) as in Example 1 is used. Will be explained. A raw material liquid having the same components as in Example 1 and a viscosity of 100 mPa · s was prepared.

  Subsequently, the raw material liquid and the stirring bar 2 for the magnetic stirrer 3 were placed in the pressure vessel 1 and sealed, and then pressurized by feeding compressed air into the pressure vessel 1. In the raw material liquid in which the stirrer 2 is enclosed, the stirrer 2 is rotated by the magnetic stirrer 3 so that the raw material liquid is constantly stirred and the mixed state is maintained in which the solid content is dispersed in the raw material liquid.

  Here, the nozzle diameter of each inkjet nozzle was set to 60 μm and 40 μm at the same ratio according to the particle size distribution of the granulated product to be produced and the conditions such as the viscosity of the raw material liquid. Moreover, it set so that the voltage of 5V and 70KHz might be applied with respect to a piezoelectric element from the alternating current generator 5 for inkjet nozzle drive. Depending on the discharge state of the droplets measured by the measuring means, fine adjustment of the driving frequency of the piezo element may be required, but the upper limit driving frequency of the piezo element is based on the nozzle diameter and ejection speed of the inkjet nozzle. Calculated and set to 720 KHz.

  The mixed raw material liquid is supplied into the inkjet nozzle of the discharge unit. The pressure to the supplied raw material liquid was adjusted so that this raw material liquid was discharged at a constant speed of 10 m / s. The droplet discharge state was measured using a CCD camera as in Example 1.

The droplets formed from the raw material liquid discharged from the discharge ports of the inkjet nozzles with different nozzle diameters are guided in such a way that droplets of different sizes are formed and then blown at a constant speed toward the opening of the drying unit. And introduced into the same drying section from the opening. The droplets were dried in an environment with a drying temperature of 300 ° C. and an air volume of 4 m ³ / min to obtain a granulated product.

  The granulated product granulated in the drying section was collected in a granulated product collecting container 9 using a cyclone 8 installed at a hot air outlet. Further, the fine powder that could not be collected by the cyclone 8 was collected using a fine powder collecting device (bug filter 10) and collected in the fine powder collecting container 11. As a result, most of the granulated material was collected in the granulated material collection container 9, and almost no granulated material was collected in the fine powder collection container 11.

  The ferrite precursor (granulated material) collected in the granulated material collection container 9 in Example 2 was photographed with SEM, and the ferret diameter of 100 ferrite precursors (granulated materials) was measured. The average particle diameter (number average particle diameter) D and standard deviation σ were calculated from the measured ferret diameter of the dried product, and the CV value was calculated as standard deviation σ / average particle diameter D. A particle size distribution diagram of the ferrite precursor (granulated material) collected in the granulated material collection container 9 is shown in FIG. As a result, a ferrite precursor (granulated product) having a particle size distribution having peaks in the vicinity of 100 μm and 76 μm is obtained. The average particle size of the ferrite precursor (granulated product) is D = 90.5 μm, and the standard deviation of the particle size. Was σ = 14.9 μm, and the CV value was (σ / D) = 0.16. That is, it can be said that a granulated powder having a particle size distribution according to an arbitrarily set nozzle diameter can be produced, and a granulated powder having a particle size distribution according to the design can be produced by a simple process.

Granulation method using granulator: Example 3 is an example in which the solid content in the raw material liquid is different from that in Example 1. That is, using the same granulator as in Example 1, the same Mn—Mg—Sr ferrite precursor (granulated product) as in Example 1 was produced. Therefore, since the granulation apparatus of Example 3 is the same structure as Example 1, description of the granulation apparatus is omitted.

  First, a raw material liquid was prepared. 25 liters of water is put into a bead mill having a capacity of 40 liters, and then, as a raw material, 3.11 kg of iron (III) oxide, 1.78 kg of manganese trioxide, 0.114 kg of magnesium hydroxide, and 0.144 kg of strontium carbonate are added. I put it in. In addition, 250 g of PVA having a solid content of 10 wt% was added as a binder component. Furthermore, 275 g of a special polycarboxylic acid polymer surfactant having a solid content of 60 wt% as a dispersant and 125 g of powdered xanthan gum as a thickener were added. Then, the mixture was pulverized and mixed for 2 hours, and the prepared slurry was filtered through a 635 mesh stainless steel net to remove coarse particles to prepare a raw material liquid. As a result, the solid content of the raw material liquid was 16.7 wt%, and the viscosity was 200 mPa · s.

  Subsequently, the raw material liquid and the stirrer 2 for the magnetic stirrer 3 were placed in a liquid storage part, sealed, and then pressurized by feeding compressed air into the liquid storage part. In the raw material liquid in which the stirrer 2 was enclosed, the stirrer 2 was rotated by the magnetic stirrer 3 so that the raw material liquid was constantly stirred and the mixed state in which the solid content was dispersed in the raw material liquid was maintained.

  Here, the nozzle diameter of each inkjet nozzle was set to 60 μm depending on the particle size distribution of the granulated material to be produced and the conditions such as the viscosity of the raw material liquid. Moreover, it set so that the voltage of 5V and 70KHz might be applied with respect to a piezoelectric element from the alternating current generator 5 for inkjet nozzle drive.

  Then, the mixed raw material liquid is supplied to a discharge unit connected to the liquid storage unit. The pressure to the supplied raw material liquid was adjusted so that the raw material liquid supplied into the inkjet nozzle of the discharge unit was discharged at a constant speed of 10 m / s. The droplet ejection speed was measured using a CCD camera in the same manner as in Example 1.

Droplets formed from the raw material liquid discharged from the discharge port of the ink jet nozzle are guided in a form that is blown toward the opening of the drying unit at a constant speed, and are introduced into the same drying unit from the opening. The droplets are dried in an environment with a drying temperature of 300 ° C. and an air volume of 4 m ³ / min to form a granulated product.

  The granulated product obtained by drying was collected in a granulated product collecting container 9 using a cyclone 8 installed at a hot air outlet. Further, the fine powder that could not be collected by the cyclone 8 was collected using a fine powder collecting device (bug filter 10) and collected in the fine powder collecting container 11. As a result, most of the granulated material was collected in the granulated material collection container 9, and almost no granulated material was collected in the fine powder collection container 11.

  The ferrite precursor (granulated material) collected in the granulated material collection container 9 in Example 3 was photographed with SEM in the same manner as in Example 1 and Example 2, and the ferrite precursor (granulated material). Article) 100 ferret diameters were measured. A particle size distribution diagram of the ferrite precursor (granulated material) collected in the granulated material collection container 9 is shown in FIG. As a result, a ferrite precursor (granulated product) having a particle size distribution having a peak at 78 μm is obtained. The average particle size of the ferrite precursor (granulated product) is D = 78.3 μm, and the standard deviation of the particle size is σ = 13.3 μm and the CV value was (σ / D) = 0.17.

  In Example 3, a raw material liquid having a smaller solid content than that in Example 1 was used. However, the same results as in Example 1 were obtained in terms of both the standard deviation of particle size and the CV value. From this, since xanthan gum was added as a thickener, it was possible to prevent sedimentation of the solid content, and it can be said that the thickener is effective when producing using a raw material liquid with a low solid content. Therefore, by adding a thickener in a range not exceeding 500 mPa · s, a granulated product having a stable quality can be obtained.

Comparative example

As a comparative example, the same raw material liquid as in Example 1 is prepared, granulated using a nozzle atomizer method (Comparative Example 1) and a disk atomizer method (Comparative Example 2), and compared with Example 1.
[Comparative Example 1]
Comparative Example 1 uses a drying mechanism in an environment with a drying temperature of 300 ° C. and an air volume of 4 m ³ / min, which is the same as in Example 1, and includes a nozzle atomizer in this drying mechanism to generate droplets in the drying mechanism. did. That is, the same raw material liquid supplied from the outside of the drying mechanism as in Example 1 is sprayed using a compressed air from a two-fluid nozzle disposed inside the drying mechanism to form droplets, The droplets were circulated to change into a granulated product and granulated. And the granulated material dried and granulated by the drying mechanism was collected using the cyclone installed in the discharge port of the hot air, and collected in the fine powder collection container. Furthermore, the fine powder that could not be collected by the cyclone was collected using a fine powder collecting device (bug filter) and collected in a fine powder collecting container. At this time, 15% of the total granulated material weight (the weight of the granulated material collected in the granulated material collecting container + the weight of the granulated material collected in the fine powder collecting container) is contained in the fine powder collecting container. % Were collected.

  As a result of measuring the ferrite precursor (granulated material) collected in the granulated material collection container in Comparative Example 1 by the same method as the example, the average particle size was D = 86.8 μm, and the standard deviation of the particle size Σ = 38.2 μm, and the CV value was (σ / D) = 0.44. A particle size distribution diagram of the granulated product obtained in Comparative Example 1 is shown in FIG.

[Comparative Example 2]
In Comparative Example 2, the same raw material liquid as in Example 1 was used, and a disk atomizer placed in a drying mechanism maintained in an environment with a drying temperature of 300 ° C. and an air volume of 4 m ³ / min was rotated to The raw material liquid supplied from is dripped onto the rotating disk and scattered by the centrifugal force of the disk to form liquid droplets, and the liquid droplets are circulated in the drying mechanism and transformed into granules. The granulated product was granulated and collected by a collection mechanism. And the granulated material granulated by drying with a drying mechanism was collected in the granulated material collection container using the cyclone installed in the discharge port of the hot air. Furthermore, the fine powder that could not be collected by the cyclone was collected using a fine powder collecting device (bug filter) and collected in a fine powder collecting container. At this time, the fine powder collecting container is the weight of the whole granulated material (the weight of the granulated material collected in the granulated material collecting container + the weight of the granulated material collected in the fine powder collecting container). 25% was collected.

  As a result of measuring the ferrite precursor (granulated material) collected in the granulated material collection container in Comparative Example 2 by the same method as the example, the average particle size is D = 42.9 μm, and the standard deviation of the particle size is σ = 23.4 μm, and the CV value was (σ / D) = 0.54. A particle size distribution diagram of the granulated product obtained in Comparative Example 2 is shown in FIG.

[Comparative Example 3]
The same raw material liquid, liquid storage unit and drying means as in Example 1 were used, and the part using the continuous ink jet method in Example 1 was changed to a piezo ink jet nozzle. That is, in Comparative Example 3, by driving the piezo element, droplets are ejected from the ink jet nozzle and the raw material liquid is introduced into the nozzle. This inkjet nozzle uses 20 μm nozzles with a nozzle diameter of 20 μm and a horizontal array of 128. The piezoelectric element applies a sine wave AC voltage with a frequency of 8 KHz and an amplitude of 80 V to form droplets. I did it. The droplet discharge speed was measured by photographing with a CCD camera disposed on the side of the inkjet nozzle using a strobe synchronized with the drive frequency of the inkjet piezo element, and adjusted to 10 m / s. The granulated product is collected by a collection mechanism.

  As a result of carrying out under the above conditions, almost all nozzles were clogged after several tens of seconds from the start of granulation, and no granulated product was obtained. As a result, in the piezo-type ink jet device, the raw material liquid always accumulates once in the ink reservoir in the ink jet nozzle. Therefore, depending on the composition of the raw material liquid, if the flow of the raw material liquid stops even in a short time, the solid content settles and the nozzle is clogged. The possibility increases, and it can be said that droplets cannot be formed under the conditions of the raw material liquid that can be used in the granulation method of the present invention.

[Contrast between Example and Comparative Example]
Table 1 shows the average particle diameter D, standard deviation σ, and CV value (σ / D) of the particles obtained in Examples and Comparative Examples. Focusing on the standard deviation, the standard deviation of the example is smaller than that of Comparative Example 1 and Comparative Example 2. That is, it can be understood that the example has powder characteristics with a sharp particle size distribution as compared with the comparative example. Further, as for the CV value, the value of the example is smaller than those of Comparative Example 1 and Comparative Example 2. That is, it can be said that the example is a granulated product with a very sharp particle size distribution with less variation in particle size compared to Comparative Example 1 and Comparative Example 2.

  In addition, in the present Example and the comparative example, although manufacture of the ferrite precursor (granulated material) was illustrated, it is not limited to this, For example, various metal powder, an oxide, edible powder, pharmaceutical , Fertilizers, color materials, photosensitive materials, fragrances, cosmetics, and the like, which are suitable for granulated products in which management of particle size and particle size distribution is important.

  In the granulation method, the granulated product, and the granulation apparatus of the present invention, the size is controlled at the stage of droplets formed from the raw material liquid for each inkjet nozzle using the continuous inkjet method, and then the liquid is supplied to the drying mechanism. Since granulation is performed by introducing droplets and drying, a granulated product having a sharp particle size distribution in a wide range of compositions while being able to control the particle size in a wide range, or granulation that forms an arbitrary particle size distribution An object can be manufactured with high accuracy. Thereby, a manufacturing process can be shortened and it can be set as the granulation method with few production losses. In addition, it is possible to granulate a granulated product consisting of multiple types of ingredients in one batch, and further granulate from a raw material liquid containing solids and binder components, thus reducing the manufacturing cost of a wide variety of types of granulated products. can do. Therefore, a granulation method, a granulated product, and a granulation apparatus that shorten the manufacturing process and realize a high yield can be used in various fields.

  In particular, when used for granulation of a ferrite carrier, image defects caused by the carrier can be reduced by aligning the particle size and narrowing the particle size distribution, and high image quality can be expected. That is, by reducing the content of fine particles having a desired particle size or less, it is possible to reduce image defects such as carrier scattering, white spots caused by the scattering, and white streaks due to scratches generated on the photosensitive drum. Furthermore, in the granulated powder produced by the conventional granulation method, it is necessary to classify a plurality of times in order to obtain a desired particle size distribution. However, if the granulation method of the present invention is used, a desired particle size is obtained during granulation. The distribution can be intentionally controlled, the classification process can be omitted, and there is an effect in terms of manufacturing cost.

In general, the amount of binder added during granulation is increased, and if appropriate firing and sintering are performed according to each application, the binder component is fired by voids released as a gas such as CO ₂ and H ₂ O. The contact reaction interface area of the granulated product after sintering can be increased. Therefore, when producing a granulated product using the granulation method of the present invention and in the subsequent steps, the granulation conditions including the performance of the binder component and the conditions for the amount of addition and the conditions such as firing and sintering are appropriately set. If set, the contact reaction interface area can be increased even if the particle size is large, and the activity in the case of performing a chemical reaction such as redox can be increased. This makes it possible to produce highly reactive granulated products while solving the handling problems such as shelves and aggregation caused by fine particles, and the raw material powder used for dielectrics and battery materials, and high water solubility. This is effective when granulating a granulated product or the like that is required. Furthermore, in the granulation method of the present invention, a granulated product having an arbitrary plurality of particle sizes can be produced, so that the filling amount can be increased by making the particle size distribution so as to fill the voids between the particles. Become. Thus, by improving the handleability and simultaneously realizing an increase in the specific surface area and the filling amount, creation of dielectric / battery materials with higher performance than ever can be expected.

1 is a schematic view of a granulating apparatus of Example 1. FIG. It is a figure which shows the particle size distribution of Example 1- Example 3. FIG. It is a figure which shows the particle size distribution of the comparative example 1 and the comparative example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pressure vessel 2 ... Stirrer 3 ... Magnetic stirrer 4 ... Inkjet nozzle part 5 ... Ink jet nozzle drive AC generator 6 ... Drying chamber 7・ ・ ・ Drying mechanism 8 ・ ・ ・ ・ Cyclone 9 ・ ・ ・ ・ Granule collection container 10 ・ ・ ・ ・ Bug filter 11 ・ ・ ・ ・ Fine powder collection container

Claims (18)

A granulation method for forming particles from a raw material liquid using a continuous ink jet method,
Supplying a raw material liquid containing a solid content and a binder component into one or more inkjet nozzles of a continuous inkjet apparatus;
A droplet is formed by discharging the supplied raw material liquid from the inkjet nozzle,
Introducing the droplet into a drying means for drying the droplet;
A granulation method characterized by drying the introduced droplets to obtain a granulated product. The granulation method according to claim 1, wherein the discharge state of the raw material liquid is controlled so as to form a desired droplet diameter while monitoring the droplets formed by being discharged from the inkjet nozzle. . 3. The granulation method according to claim 1, wherein when two or more inkjet nozzles are used, an average droplet diameter of droplets formed from each inkjet nozzle is set for each nozzle. 3. The structure according to claim 1, wherein when two or more inkjet nozzles are used, droplet components are formed by changing a component of droplets formed from each inkjet nozzle for each nozzle. Grain method. The granulation method according to any one of claims 1 to 4, wherein the solid content of the raw material liquid includes one or more components selected from an inorganic substance and an organic substance. The granulation method according to any one of claims 1 to 5, wherein the raw material liquid is used after removing coarse particles with a filter of 500 mesh or more. The granulation method according to any one of claims 1 to 6, wherein the raw material liquid is used with a viscosity of 500 mPa · s or less. The granulation method according to any one of claims 1 to 7, wherein a thickener is added to the raw material liquid. The granulation method according to any one of claims 1 to 8, wherein a nozzle diameter of the inkjet nozzle is selected and used within a range of 20 µm to 120 µm depending on a particle size of particles to be formed. The discharge of the raw material liquid from the ink jet nozzle is to continuously supply the raw material liquid into the ink jet nozzle at a constant speed and to discharge at a constant speed by the supply raw material liquid pressure.
And the pressure fluctuation is added to the raw material liquid flow which passes the inside of an inkjet nozzle, The granulation method in any one of Claims 1-9 characterized by the above-mentioned. The pressure fluctuation applied to the raw material liquid flow is performed by using a piezo element and changing the pressure by controlling a voltage applied to the piezo element. The granulation method as described. Manufactured using the granulation method according to any one of claims 1 to 11,
A granulated product having an average particle size of 5 μm to 500 μm. A granulation apparatus for performing the granulation method according to any one of claims 1 to 12,
Liquid storage unit, discharge unit, drying unit, collection unit are arranged in series,
The raw material liquid stored in the liquid storage part is continuously supplied to one or more inkjet nozzles provided in the discharge part,
The raw material liquid in the ink jet nozzle is ejected from the ink jet nozzle by a continuous ink jet device provided in the ejection part to form liquid droplets, and the liquid droplets are introduced into the drying part,
A granulating apparatus characterized in that the introduced droplets are dried in a drying section to form a granulated product, and the granulated product is collected in a collecting unit. 14. The granulating apparatus according to claim 13, wherein a nozzle diameter of the inkjet nozzle is selected and used in a range of 20 μm to 120 μm according to a particle diameter of particles to be formed. 14. The discharge state of the raw material liquid is controlled by the continuous ink jet device so that the average particle size of the granulated product to be produced has a desired average particle size between 5 μm and 500 μm. Item 15. The granulating apparatus according to Item 14. A measuring means for measuring a droplet diameter of the formed droplet is provided, and the discharge state of the raw material liquid is controlled so as to obtain a predetermined droplet diameter according to a measurement result by the measuring means. The granulation apparatus according to any one of claims 13 to 15. When the two or more ink jet nozzles are used, the continuous ink jet apparatus controls a discharge state of the raw material liquid according to a shape and / or a component of a droplet to be formed for each ink jet nozzle. The granulator according to any one of Items 13 to 16. The liquid storage section includes a stirring mechanism that stirs the raw material liquid and maintains the mixed state, and the stirring mechanism maintains a state in which the solid content contained in the raw material liquid is uniformly dispersed in the raw material liquid. The granulator according to any one of claims 17 to 17.

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