(1) Clarifying fixing mechanism in printing

Mr. Hiroshi Urakawa giving explanation on future dyeing processes

Mr. Hiroshi Urakawa, the director of the textile processing development division of the Center for Fiber and Textile science at the Graduate School of Science and Technology of Kyoto Institute of Technology, gave a lecture entitled "What is in store for dyeing processes in the new era?" at a regular technology symposium of the Nihon Senshoku Kako Dogyo Kai (the Japanese Dyeing & Finishing Industry Association) held on June 8 at the Osen Building in Chuo-ku, Osaka. The summary of the lecture of Mr. Urakawa is as follows.

"Ink-jet printing for fabrics has potential functions for new dyeing processes in the future. Current ink-jet printing machines for fabrics are categorized into types for printing, but, to develop them into types for new dyeing processes, it is important to examine the pretreatment process as an operation before ink-jet printing and necessary to do research on methods for fixation after printing.

Unfortunately, there is not much basic research on fixation for printing at this point. For example, even the role of urea regarded as being essential for color improvement has not been explained in detail. To find out about future dyeing processes, the mechanism of fixation for printing by ink-jet needs to be clarified. Basic research on this matter is necessary.

To carry out the research, we have a newly-developed, contact-type, dry-heat fixation method. We have proceeded with the research to examine detailed changes in color performance through changing concentration and treatment temperature of water and urea to find out each one's role. This is very important for dyeing fixation on fabrics. In the experiment, we have confirmed that if there is a low molecular, gaseous state which has a significant affinity for a certain type of fabric during the operation, the fixation is remarkably enhanced."