We investigated the corrosion behavior of Co-polyacetal (Co-POM) in nitric acid (HNO3) solution and evaluated the degree of degradation by following the changes in weight, dimension, color, flexural strength, and molecular weight. After immersion, the surface of the specimens changed from white to yellow. The specimen weight in HNO3 solution decreased after an incubation period. When the specimens immersed in distilled water were dried, the flexural strength recovered to nearly its initial value; however, this was not observed for specimens that were immersed in HNO3 solution and then dried. From size exclusion chromatography measurements, it was observed that the degradation of Co-POM by the HNO3 solution was limited to near the surface of the specimen, whereas the interior had remained nearly intact. The corrosion rate was calculated from the thickness of the corrosion layer, and the residual thickness of the uncorroded layer and the flexural strength after immersion could be predicted according to the estimated corrosion rate. From this study, it was inferred that the degradation of Co-POM by HNO3 solutions is of the corroded layer-forming type.
The effect of dispersion factors on the diameter of titanium dioxide powder dispersed with a micro-bead type bead mill was investigated. The dependence of the median diameter of dispersed powder on dispersion time and specific energy were investigated using various experimental variables such as bead size, filling rate of beads, agitator peripheral speed, bead materials and particle size of the feeding raw material. In addition, dispersion efficiency of different stirrer disk shape and different bead mill structure was compared using a micro-bead type bead mill and a high-flow circulation type bead mill. As a result, when a bead mill with beads of a fixed size was used to disperse a feed raw material of fixed particle size and fixed slurry solids content, the diameter of the dispersed powder was found to depend on the specific energy. Especially, we clarified that the dispersion efficiency of the bead mill, from the viewpoint of specific energy, is greatly influenced by the bead size.
Viscous lyotropic liquid crystals can be formed at relatively high surfactant concentration. Gel emulsions can be formulated by dispersing water or oil in these lyotropic liquid crystals. After briefly describing formulation and rheological properties of O/H1-type and O/I1-type gel emulsions, preparation of transparent gel emulsions was described. O/H1-type and O/I1-type gel emulsions are normally turbid due to the difference in the refractive indices of continuous and dispersed phases. However transparent gel emulsions can be obtained by adding glycerol due to contrast matching with respect to refractive indices of continuous and dispersed phases.
For the development of cosmetic foundations that achieve beautiful skin appearances, control of their optical properties is critical. The control is achieved by mainly two approaches: synthesis of pigments that exhibit desired optical behaviors; fabrication of pigmented layers that exhibit desired optical behaviors. Based on these approaches, various techniques for the control of reflection, the most important optical properties, have been reported. In this paper, basic knowledge regarding reflection is firstly introduced. Then, prominent techniques for the reflection control of foundations are reviewed. In this review, previous studies that aimed the visually naturo-beautiful skin are mainly illustrated. Finally, technical problems on current optical control techniques are described.
In recent years, “Flexography” is coming to more attention because of a rising awareness of environmental issues. Flexographic printing process uses rubber or photopolymer plate which is flexible and resilient, and thanks to flexible printing plate, we can have quality printing results on rough surface substrates. Flexible printing plate, however, is one of the impediments to reproduce fine image, such as highlight dot, fine text, fine line and so on. In order to overcome such disadvantages and obtain higher printing results, a lot of innovations have been developed. “Flat Top Dot” technology is one of the latest evolutional printing plate making technologies in flexography and much attention is focused on it now. In this article, we describe what is “Flat Top Dot” technology and its several methods to form printing plates.
In today's automotive painting, further reduction of carbon dioxide, volatile organic compound (VOC) emissions and multi-color paint is required. As a solution to contribute in the solving the problem, recent automotive paint technologies are described. For the atomizer, four technologies are described: high paint flow technology by high performance air motor, spray pattern width control technology which can contribute to reduction amount of over spray paint, flushable cartridge system which can contribute to reduction of the paint booth area and multi-color paint and the contamination proof system for the electrostatic atomizer with water borne paint. The paint robot, a wall-mounted robot which has wide moving area and high acceleration is described. This robot can contribute to reduction of the paint booth area. The painting control technology, a general configuration, the basic control methods, the delay compensation and recent monitoring system are also described.