Cellulose materials are being reviewed as a printing material for packaging containers. The trade-off between image density and rub resistance is an issue for cellulose materials, as typified by paper. In this study, among intermolecular forces, we focused on the CH/π hydrogen bonding force, which is not easily affected by water, and focused on the direct dye structure that enables the CH/π hydrogen bonding force to work on the cellulose backbone. The rub resistance was improved by imparting the direct dye to the printing paper in advance, and was further improved by incorporating the direct dye structure into the polymer dispersant. As a direct dye structure superior in rub resistance, we found the following four points, referring to the electrophilic aromatic substitution: (1) having a long conjugated double bond backbone, (2) having many electron-donating substituents, (3) having a low sum of intramolecular substituent constants, and (4) having an asymmetric structure.
Colorants with Direct Black 22 introduced into polymeric dispersants that meet these four conditions exhibit both high print density and excellent rub resistance.
Additives, which are one class of raw materials for paints, are indispensable materials for preventing paint defects, and for obtaining highly functional and designable coating films. Additives are auxiliary elements for forming the coating film, and they are important raw materials that affect the performance and application suitability of paints. This paper describes the types and actions of additives that play important roles in the paint manufacturing process and coating film formation process, such as thixotropes, dispersants, leveling agents, and defoamers, and introduces how to use them.
In recent years, the binder jet method, which enables high-speed modeling by increasing the number of nozzles, has appeared in the metal modeling of 3d printers, and is actively applied mainly to overseas manufacturing processes. In this paper, we explain the metal modeling technology using inkjet and show the features of each method by each manufacturer. This technology is still under development and poses challenges for existing processing technologies that should be addressed with the binder jet method. We hope that it will contribute to future development, such as the fusion of craftsmanship and digital technology, by taking advantage of the strengths of the Japanese manufacturing industry.
The history of the development of painting production technology in the automotive industry of Japan was collated. 550 items related to automobile painting production technology were selected from the technical information posted from the first issue (1966) to the latest issue (2022) of the magazine “Toso-Kogaku” of the Japan Coating Technology Association. This technical information was classified as “Coating systems and equipment”, “Water-based paints and painting”, “Electrodeposition coating”, “Powder coating”, and “Current trends such as IoT and DX”. We can get hints for solving problems by learning the history of the development of painting production technology. We can achieve difficult tasks such as achieving carbon neutrality by collaborating across the boundaries of companies and industries.
For many years, Honda Motor Co., Ltd. has been working on enhancing the appearance of the paint on the fuel tank, which is the “face” of a motorcycle. In 1988, the first high-quality appearance painting system for fuel tanks was introduced at the Hamamatsu Factory. It was a revolutionary product that enabled thick-film coating that surpassed normal limits. However, with the subsequent diversification of product specifications, it was confirmed that there were differences in the level of appearance quality depending on model and part. In 2008, when a new factory was constructed at Kumamoto in conjunction with the consolidation of domestic sites, we used a factor analysis of the issues related to the first generation system to undertake the development of (1) a sagging limit control system as an optimal coating method with enhanced shape followability by stopping on three sides, and (2) a drying oven. With the latter we worked on the development of a paint film shrinkage control system as an optimum paint film curing method by zone-specific environmental control. As a result, we succeeded in achieving the world’s top level fuel tank exterior painting.