Nobushige Numa

Coating resins synthesized from recycled PET

PET bottles collected from the Japanese market have been increasing year by year. In 2000, a total of 124,873 t of PET bottles were collected for reprocessing. Reprocessed PET is called recycled PET (hereinafter called R-PET), and 68.575 t of R-PET was used as raw materials for fibers, sheets, and various other uses in 2000. Regarding R-PET as a condensation polymer composed of ethylene glycol (EG) and terephthalic acid (t-PA), we have tried to utilize it in coating resin syntheses. Polyesters for powder coatings synthesized from R-PET in place of EG and t-PA showed the same structure and characteristics as a conventional polyester synthesized from ordinary EG and t-PA monomers. An alkyd resin for ambient temperature curing coatings was synthesized from R-PET as a substituent for EG and phthalic anhydride (PA). After modifying its monomer composition, it finally showed the same characteristics as the original resin. The use of R-PET in alkyd and polyester resin syntheses provides a beneficial means for mass consumption of R-PET.

Application of graft copolymers using macromonomer method to two-component polyurethane coatings

Abstract Graft copolymers as acrylic polyols in two-component polyurethane coatings were prepared by the free-radical copolymerization of methyl methacrylate, n-butyl methacrylate, n-butyl acrylate, acrylic acid, 2-hydroxyethyl methacrylate and poly(methyl methacrylate)-macromonomers. The poly(methyl methacrylate) macromonomer was prepared by the polymerization of methyl methacrylate in the presence of thiopropionic acid as a transfer agent followed by the reaction with glycidyl methacrylate. These polymers, whose numbers of poly(methyl methacrylate) macromonomer branches and the molecular weights of the poly(methyl methacrylate) macromonomer branches were controlled, offer an advantage over conventional resins with respect to the application/appearance of coatings as well as the final film properties. Some of these advantages were higher solids and a better control of the coating rheology, an increase in the cross-linking reactivity of the polyols with polyisocyanate and improvement in film toughness. The change in the morphological structure of the films under tensile stress was of particular interest.

Study on thermal crosslinking reaction of o-naphthoquinone diazides and application to electrodeposition positive photoresist

The thermal reactions of o-naphthoquinone diazide (NQD) compounds as a material for photoresists were studied in comparison with their photochemical reactions. An NQD compound decomposed at around 140°C and further reacted in the presence of an alcohol in the solution to yield an indenecarboxylic ester. The photochemical reaction of the NQD compound with alcohol also provided the same ester in a solution, as expected. In a polymer matrix, the thermal reaction of a multifunctional NQD compound with a copolymer having hydroxyl groups yielded sufficiently crosslinked structures at 140°C in 10 min. On the other hand, when the copolymer matrix containing the NQD compound was exposed to UV, and subsequently to heating (140°C for 10 min), no crosslinked structure was obtained. Consequently, it was confirmed that the heating provides a large difference in solubility between unexposed and exposed areas, quite a useful feature from the viewpoint of efficient development of photoimage. We have applied this finding to an electrodeposition positive photoresist incorporating a post exposure bake (PEB) in resist processing. The PEB afforded a very wide process window in an alkaline developer.