Discovery of Grindstone ~ Start of Hosokawa Micron ~

The birthplace of Mr. Eiichi Hosokawa, the founder of the Hosokawa Micron Corp, is located in Sumoto on the Awaji Island and now becomes a paddy field. When Mr. Yoshio Hosokawa, the president of the Hosokawa Micron Corp, visited there, he happened to find grindstones laying in the corner of the field. Though it is not sure how old these stones are, they must be the grindstones with which Eiichi was playing in his childhood for grinding powders in the water mill hut in the neighborhood. These grindstones were then transferred to the Hosokawa Micron Headquarter in Osaka and are being displayed near the main gate. It is amazing to see these hundred years old grindstones, which are the symbols of the long history of the grinding technology.

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In supercritical water, ions are un-stabilized because of the lower dielectric constant, and metal oxides formed from metal salts. Thus, supercritical water is a good reaction atmosphere to synthesize nano metal oxides, when a metal salt solution is rapidly heated up to the supercritical state. To achieve the rapid heating, flow type reaction process in which metal salt solution is rapidly mixed with high-temperature water was employed. In most of the cases for nanoparticles applications (nano fluids/nano composite materials), nanoparticles have to be well-dispersed in solvents/polymers at high concentration, with keeping fluidity high. Thus, affinity control between the particles and matrix is the critical issue. In supercritical water, organic ligands can be miscible with water due to the low dielectric constant, so that in situ surface modification is possible during the synthesis of nano metal oxides. Based on this nano materials synthesis technology, a variety of applications of nanoparticles is expected including nano hybrid materials and nanocatalysts.

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Solid-liquid separation includes a variety of operations such as filtration, expression, centrifugation, etc., and it plays an increasingly important role in widely diversified fields ranging from industry to environmental protection. In recent years, membranes have been successfully applied also to solid-liquid separation to attain a higher level of separation. This paper describes several new topics on the developments of solid-liquid separation technologies. A method was introduced for obtaining the pressure dependences of properties of filter cake of nanocolloids from a single dead-end filtration experiment. Filtration behaviors were evaluated based on the compression-permeability data obtained from analytical centrifugation. Parallel and series resistance models were proposed for describing the membrane fouling occurring for membranes with different structures. A method has been developed for individually evaluating the mechanism and degree of membrane fouling based on a limited amount of filtration data. It was shown that ultrahigh-pressure expression combined with reversible flocculation achieved the high rate and high-degree deliquoring of excess activated sludge. Moreover, it was found that the excess activated sludge treated by ultrasonication exhibited a significantly high settling rate with the aid of inorganic salts. I believe that these results provide new insight into the developments of solid-liquid separation technologies.

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The internal structure of the films, which is manufactured by coating and drying of particle dispersion, usually has significant effects on the performance. Therefore, the understandings of the concentration of dispersions and the packing of particles are strongly required for establishing sophisticated manufacturing process. The internal structure composed of aggregated particles in the dispersion is destroyed under shear deformation depending on the condition, and the deformation behavior can be understood based on rheological analysis. The combination of film shrinkage and weight loss during the evaporation of solvent is useful to characterize the concentration and packing processes of dispersed particles. Additionally, light scattering on the surface of drying film of particle dispersion can exhibit the progress of aggregation of the particles. In the present article, how three characterization techniques shown above are useful in the analysis of the drying process of the film of particle dispersion was described. How shear strain in the coating process affects the initial structure of particle dispersion and how the following drying process is changed have been discussed.

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In the design of the functional particles, we have been required the technology to prepare the high drug loading fine spherical particles, which has not been established yet. We have studied a solution to the above problem, and succeeded in creating a high-loading spherical granules (Opusgran^®) by high-speed stirring granulation and novel idea. Also, we found that this granule has a hollow structure. The success of the production of Opusgran^® granules does not depend on the solubility and any characteristics of the drug. And it does not depend on any functions and the particle size of the polymer, either. Opusgran^® granules can be produced from all of the drug substance and all of the polymer. The primary advantage of Opusgran^® is that it can impart a function of the polymer used for the granules. For example, we obtained the high-loading fine spherical granules of poorly soluble compound with release controlled for more than 24 hours by sustained release polymer. In addition, we can easily obtain functional tablets without losing the function of Opusgran^® by tableting. So, in the future, we will be able to produce almost all solid dosage forms with various functions by only this Opusgran^® technology.

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All-solid-state rechargeable batteries with inorganic solid electrolytes have a big advantage of high safe and reliability. A key material for realizing solid-state batteries is a solid electrolyte with high conductivity and favorable formability. Glass-based Li⁺ or Na⁺ ion conductors were prepared via a mechanochemical process using a planetary ball mill apparatus. Prepared glass particles are useful for forming good electrode-electrolyte contacts. Amorphous positive electrode active materials were also prepared via mechanochemistry, and they showed a high capacity and good cyclability. In this study, recent development of amorphous solid electrolytes and positive electrodes of sulfides and oxides is reported.

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The demands for finer powder and functional powder have been increasing year by year according to downsizing of each product or saving energy. In order to catch up with this situation, we also tackle developing new innovative machine like grinding machine or classifier and so on. In this paper, I introduce the machine developed recently and explain the principle of each machine.

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The novel dry milling technique, i.e. “spherical pulverization”, has been developed by using a mechanical powder processor. It was found that the model drug crystals with more than 100 μm in diameter were well pulverized by co-processing with fine particles of corn starch (CS). The morphological observation and particle size evaluation revealed that the processed products formed the composite particles with ordered-mixed structure, having double-layered particles with a core of CS and a coating layer of drug crystals. This result suggested that the drug crystals were selectively micronized and the resultant miniaturized drug particles were adhered/fixed on the surface of un-milled CS particles. The mechanical characteristics detected by the indentation test assumed that the brittle drug crystals sandwiched between elastic CS particles would be successfully crushed down by high shearing stress in the processor. The dispersion-sedimentation test indicated that the fine drug particles were immediately detached from the composite particles in aqueous phase, constructing the fine suspension. The dissolution behavior from the processed particles was found to be improved and strongly dependent on the size and amount of detached drug particles. These results would propose the contamination-free dry milling technique without using hard milling balls or beads.

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Risk and safety measures of dust explosions are described in this article. Combustible dust has the risk of dust explosion when it is suspended in air under some conditions. The dust is solid and it cannot burn like a premixed flame appeared in gas explosions, however, a flame can propagate rapidly and the phenomenon becomes explosion. The three factors of combustion, suspended combustible dust, ignition source, oxygen, are necessary for dust explosion. This point is important to think about safety measures of dust explosions. The main characteristic values (lower explosion limit, minimum ignition energy, limiting oxygen concentration, maximum explosion pressure, rate of pressure rise) used for hazard estimation are explained, which are categorized using risk concept into two kinds, characteristic values for occurrence and that for severity of dust explosion accidents. Also some of safety measures are explained.

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We will introduce a new pleated type pulsjet collector developed for the purpose of using at high concentration where cylindrical filters are conventionally used such as pneumatic transportation and product collection of pulverizers. The new pulse jet collector has been significantly downsized compared with the pulsejet collector using the conventional cylindrical type of filters by adopting a newly designed pleated type filters. The newly designed filter was designed to obtain the maximum effective area at the same diameter of conventional filter. Also, in accordance with the increase in the effective area, we reviewed the venturi design and the shape of the blow nozzle where the compressed air goes through and strengthened the cleaning power. Furthermore, the cleaning power for each filter was made uniform, and the inlet design was made considering the flow inside the bag housing. As a result, it was confirmed that it was possible to operate it at high concentration as the pulse jet collector using the conventional cylindrical filters in demonstration tests with typical powders.

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According to the Occupational Safety and Health Act revised last year, risk assessment is obliged for certain hazardous chemical substances, and all the users must grasp the risk and take the necessary measures to reduce it at the manufacturing site. Also in our company, there are an increasing number of cases when testing with special materials or examining the environmental improvement is carried out at the site where our powder equipment is used. This time we will summarize the containment technologies used for the environmental improvement and introduce the relevant equipment.

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The CRS classifying rotor has a new unique structure which achieves the classification of super fine powders by the effect of semi-free vortex inside the high speed rotor and is easier to disassemble and maintain than the conventional CR classifying rotor. The AFG-CRS is the fluidized bed opposed jet mill equipped with the CRS rotor and realizes the production of submicron-sized powders.

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Various fine particles have been actively researched for Drug Delivery System (DDS) in the recent drug development. We have been developing poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles loaded with bioactive substances for pharmaceutical preparations, medical devices, functional cosmetics and so on. Regarding the practical application, the PLGA nanoparticle’s weak points such as vigorous cohesiveness and low handling property have been dramatically improved by utilizing our powder processing technologies for designing composite particles. A lot of usefulness of our developed PLGA nanoparticles has been demonstrated in various administration routes. Clinical trials of preparations and devices using our PLGA nanoparticles have already been launched in Japan. Also we have found out the enhancement of drug’s skin permeability by PLGA nanoparticles. Base on the evidences, we have already succeeded in commercialization of functional PLGA nanoparticles for skincare cosmetics and hair growth tonic.

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Even if several useful hair growth ingredients in hair tonic are applied to scale from the outside, only modestly beneficial results in hair growth are often observed.

The poor condition of the necessary ingredients for the hair growth promotion delivered to hair matrix cells by blood flow was concerned with the phenomena that above-described. The phenomena are not easy to improve by use of only the general hair growth lotion.

In this paper, we introduce the importance of “internal and external hair growth cares” with several evidences.

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These new bag filters are improved model of Hosokawa/Micron Pulsjet collector. The model as VCP has a cylindrical housing with high vacuum structure for product collection in the powder processing system, another model as VSP has a square housing used in dust collection with the use of low pressure blower, or as an air relief filter of low-pressure design. The combination of unique designed pleated filters and dedicated structure for blowing a pulse jet gas achieve a good balance between drastically increasing the filtration area per unit filter media and filtration the high dust laden air. This innovation takes to save an installation area and capacity for filtration of conventional high dust laden gas. The space saving achieves effective usage of factory space, improvement of earthquake protection due to the mass saving, and shorten the changing time of filters due to reducing the number of filter media.

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The new developed classifying assembly, model CRS, is the derivative model of CR classifying assembly which can achieve the ultra fine classifying. The CRS is suitable model to integrate within fine or ultra fine mill for manufacturing of a wide variety of products because this model has superior performance on disassembly operation and maintenance with keeping the classifying performance same as CR model on minimum particle size and capacity. Multi-wheel model is also available like as Hosokawa/Alpine Turboplex classifier and related products for request of large capacity production. This model is suitable to integrate within fluidized bed opposed jet mill, target type jet mills, or classifier.

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A lot of ACM Pulverizers have been installed in various fields all over the world. The ACM-CR is a new model of ACM Pulverizer with an integrated high performance air classifier adopted from a jet mill. Basically, ACM-CR operates with the same principles as the conventional ACM Pulverizer. The ACM Pulverizer utilizes a closed circuit grinding mechanism, and can re-grind the returned coarse material by the strong impact forces generated by the hammers and liner. The grinding rotor efficiently grinds material fed through the feed inlet. The ground powders and unground feed materials are pneumatic conveyed to the classifying section by the circulating airflow. The fine powders are conveyed through the classifying wheel and are discharged as product. The coarse material drops down along the guide ring back to the grinding chamber due to centrifugal force. ACM-CR realizes ultra fine grinding by combination of high speed grinding disc with unique developed hammers, and a unique built-in high performance classifier.

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Graphical Abstract

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Graphical Abstract

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