Polypropylene (PP) developed ca. 60 years ago has many advantages such as high strength, excellent chemical resistance and extremely low specific gravity of 0.91. However, until now there was no practical way to dye PP fiber. Therefore, application of PP fiber as apparel products was limited. We are investigating the development of dyestuffs that can dye PP fibers at a practical level. The idea is based on the principle that “like dissolves like”; some long or large hydrophobic substituents, which are similar to PP molecules, were introduced into the structure of mainly anthraquinone dyestuffs. The prepared dyestuffs were dyed using supercritical carbon dioxide fluid. The fastness of dyed PP fabric was excellent. In the textile industry aiming for SGDs, supercritical dyeing that does not use water and does not discharge waste has already been put into practical use in Asian countries for polyester knit fabric. The dyeing of PP fabric having the big advantage of these attractive properties will be industrialized in the near future. This new dyeing technique can be expected to expand globally as a key innovation for the dyeing industry.
To overcome various shortcomings associated with commercial metal-effect gloss paints containing metal flakes, the development of organic-based paints that exhibit metal-like colors has been eagerly awaited. Recently, one of the authors developed a potential candidate (ClO4－-doped oligo(3-methoxythiophene)) and its paint, but the required solvent was not industrially acceptable and the coating films displayed low glossiness. Very recently, we synthesized and characterized Cl－-doped oligo(3-methoxythiophene) dyes that were water soluble and displayed a highly lustrous gold- and bronze-like hue upon curing, the outline of which is described. Specifically, we found that films derived from these oligomers form extremely regular and compact edge-on lamella crystallites through self-organization; these films also display a highly glossy metallic appearance due to the extremely high optical constants of the crystallites. These as-prepared films were easily soluble in water, but we also found that the films become insoluble in water upon dehydration, making industrial implementation feasible.
Electron Spin Resonance (ESR) method is magnetic resonance spectroscopy that selectively detects electron spin in gas, solution and solid samples. Generally, atoms and molecules with unpaired electrons are unstable and highly reactive. In some cases, unpaired electron spin is a key to determine the characteristic of the materials. In this paper, basic principles of ESR method and application to some samples are introduced.
Colloidal suspensions are coated on substrates and upon drying produce various functional materials. The non-equilibrium structure formation of colloidal particles is induced during coating and drying’ affecting operational efficiency and material performance. To understand the relation between operation conditions and structure formation, we have developed a simulator of colloidal suspensions, SNAP. We discuss the non-equilibrium structure formation through the results calculated by SNAP.