Previously, we have reported the successful preparation of a soft flocculated suspension. This is a suspension in which fine particles are well dispersed by using a polyelectrolyte dispersing agent, and then Mg²⁺ ions are added to crosslink between the dispersants adsorbed on the surfaces of the particles, so that the particles temporarily return to a liquid state with light shaking while behaving as gels at rest.

In the present work we tried to apply this soft cohesive suspension as a low viscosity suspension of titanium dioxide having high versatility as a cosmetic powder. The use of globular titanium dioxide with a low yield value resulted in the successful development of a soft cohesive suspension with no precipitation or deposition of particles. In addition, when the application of this suspension in a white inkjet ink was examined, both the addition molding to a solid powder product using a piezo type cartridge and the printing experiment with a home printer using a thermal type cartridge showed the good results.

In order to increase the activity of wheelchair users, development of the practical application of the Sound Wheelchair has progressed. The Sound Wheelchair is a wheelchair equipped with a sensor module that converts color into sound. When the wheelchair user runs over a color panel laid on the floor, a sound corresponding to the color of the panel is output from the speaker. A current problem is that when moving from indoors to outdoors, the color sensor erroneously identifies the color of the panel and the operation becomes unstable. It is supposed this is due to a change in hue of the color panel caused by the difference in the surrounding light source. Conventionally, papers printed by a color printer have been used as the material of the color panel. In the present study, as the material of the color panel, electrostatic flocking papers are examined. Hue change values due to differences in light source were measured for both electrostatic flocking paper and printer printing paper. As a result, it was found that the electrostatic flocking paper had a smaller change in hue than the printer printing paper and was therefore more suitable as a color panel.

A novel surfactant (C7-azo-C7) containing an azobenzene skeleton has been synthesized and stable oil in water (O/W)-type emulsions consisting of n-octane and water have been prepared. Ultraviolet (UV) light irradiation of the emulsions promotes the cis isomerization of trans C7-azo-C7 and leads to the coalescence of the oil (octane) droplets in the emulsions, that is, demulsification.

Water repellency is an important surface finishing technology in various industries because chemical reactions or bond formation through water are limited on a hydrophobic surface. The hydrophobicity of the solid surface is divided into two categories: static and dynamic hydrophobicity. Recently, thanks to rapid advance and availability of high-speed cameras, CPUs, and surface nano-scale characterization techniques such as AFM, the number of research reports on dynamic hydrophobicity has increased, and the content has advanced remarkably. Technologies for droplet manipulation by internal factors of solids or external fields made a great progress through these researches and they have become a key part in designing various industrial devices. The importance of static and dynamic hydrophobicity is rapidly increasing, and merging fluid dynamics considerations with solid surface or interface chemistry is a clear trend in this field. This paper presents research topics related to static and dynamic hydrophobicity of solids in recent 4~5 years.

Carbon black is widely used very popular black pigment. However, from time to time we realize that carbon black is one of the toughest pigments to produce a very fine dispersion. When we try to disperse carbon black in a liquid medium such as printing inks, the following steps occur simultaneously or sequentially. (1) wetting carbon black with a vehicle, (2) dispersion using mechanical shearing or elongational stress by a mill or a mixer, and (3) stabilization of the whole system. Dispersing the vehicle wetted agglomerate to a much smaller size establishes good optical properties, but this process is greatly affected by the nanostructure of carbon black. In this report, we will discuss how the key nanostructures of carbon black, “structure”, would apply to the dispersion of printing inks.