The particle-dispersion state of nano-particle suspensions was evaluated by measuring their osmotic pressure. Zirconia suspensions with different particle-dispersion states were prepared by adjusting the pH value of the suspension, and their osmotic pressure and particle-size distribution were measured. For alumina and silica suspensions, the ionic concentration was adjusted to change the particle-dispersion state, and their osmotic pressure and particle concentration after centrifugation were also measured. The osmotic pressure was found to decrease with an increase in the ionic concentration due to particle aggregation caused by compression of an electrical double layer. A good correlation between the osmotic pressure and particle concentration after centrifugation of the suspensions was exhibited; thus, we can conclude that the osmotic-pressure measurement would be a useful tool to characterise the particle-dispersion state, especially for dense nano-particle suspensions.

In order to clarify the influence of the viscosity of liquid on stirring behavior, 20 subjects mixed liquid with a bar to disperse the zirconia beads when the viscosity of liquids were 1.47-1.03×10³ mPa･s. As the viscosity increased from 1.47 mPa･s to 1.03×10³ mPa･s, the score of sensory evaluation of “the ease of spreading” decreased and the stirring time required for dispersion became longer. In addition, four agitation patterns appeared depending on the viscosity of the liquid: When the viscosity of the liquid was 1.47 mPa･s, 80% of subjects stirred with a circular pattern in which relatively large circles were drawn, whereas in the case of a liquid of 1.03×10³ mPa･s, a straight pattern with linear motion or a smaller circular pattern was observed. This change is probably because in the high viscosity liquid, the energy generated by the stirring dissipates and the bead spreads only to a part of the petri dish, so the subjects switched to the more efficient stirring motion. Such a change in pattern indicates that humans sense the viscosity of liquid when stirring the liquid and adjust the movement based on the characteristic texture.

We are studying a coating system using liquefied CO₂. VOC can be reduced by approximately 50% just by replacing thinner with liquefied CO₂. In this system, carbon dioxide changes state from liquid to gas when spraying from the paint gun after mixing paint and carbon dioxide. By using the volume expansion energy, the paint is atomised into fine particles and a beautiful coating film can be formed. In this paper, we measured the transfer efficiency under various spraying conditions using the coating system. As a result, it was found that the transfer efficiency of the coating system using liquefied CO₂ is higher than that of air spray coating or airless spray coating. In particular, by setting the spray distance of 50 mm and the carbon dioxide addition amount to 16% or more, the transfer efficiency was 95% or more. In order to discover the reason for the increase in transfer efficiency, we analyzed with a high speed camera. This revealed that the amount of paint particles bouncing off the object to be coated was small, so the transfer efficiency increased.

Paints and inks include various kinds of polymers, additives and solvents. Solubility Parameter (SP) is useful to control their mutual miscibility.

At the application stage a good wetting and adhesion onto the substrates is required. To incorporate the solid particulate materials like pigments into liquid vehicles, a good wetting is also important. To consider such phenomena, knowledge about the surface properties of the component materials is indispensable. Among the surface properties, the surface tension is important.

Explanations about SP and the surface tension are briefly given. Several examples where dissolution, blending, wetting and adhesion are controlled by SP and the surface tension, will be exhibited.

Microscopic particles suspended in liquids, often called particle dispersions, can be found in many industrial processes as important materials and products. In order to handle the particle dispersions properly, evaluating the stability of the dispersions is fundamentally critical. The aggregating-dispersing behavior of the particles in liquids is dominated mainly by the interaction forces acting between the particles surfaces (surface forces). It is therefore significantly important for the precise evaluation of the dispersion stability to understand how such forces behave depending on the properties of the particle surfaces and solutions. This review provides general information on the techniques to measure surface forces directly. It also presents an overview of the studies on the direct measurements of the surface forces conducted so far, discussing the effect of nanoscopic structures and the properties of the surfaces on surface forces.

Biosurfactants (BSs) are amphiphilic molecules which are produced by microorganisms from a variety of renewable resources. They have recently attracted much attention as a relatively new class of surfactants because of a growth in environmental awareness, which led to the establishment of a new working group (WG3 biosurfactants) at ISO (International Standard Organization) TC91 (surfactants) in April 2014. BSs exhibit not only excellent surface and self-assembling properties but also versatile biological activities, compared to those commonly used surfactants. They generally can be classified into three categories; peptide (protein), glycolipid and fatty acid types, depending on the structure of their hydrophilic group. In this review, the fundamentals and applications of biosurfactants such as glycolipid (mannosyl erythritol lipid) or peptide-based surfactants (surfactin) are described.

In Europe, REACH regulation was enforced in 2007, to ensure a high level of protection of human health and the environment as well as the free movement of substances, on their own, in preparations and in articles, while enhancing competitiveness and innovation.

REACH regulation is constructed by four procedures of registration, evaluation, authorization and restriction. Manufacturers and importers of a substance on its own or in a mixture in EU are required to register, notice, provide information about SVHC for all substance including new and existing substances meeting a specific condition.

Now that it was under one year until REACH registration of existing chemicals deadline of the end of May, 2018, we introduce the outline of the REACH regulation.