Recently, many materials liquefied by exposure to light have been reported as a photo-melt resin. However, previously reported photo-melt materials tend to have complicated resin design, mechanism and synthetic pathway. In this report, the photo-melt resin was obtained from the mixture of commercially available materials, and it was assumed that the covalent bond in the polymer was cleaved by the reaction between the photo-induced radical and the disulfide bond. The photo-melt resin shows rubber elasticity and liquefied by exposure to light. When the resin was applied to the adhesive, a significant decrease in adhesiveness due to exposure was observed. This technology is expected to be applied to an easy-torelease adhesive, temporary adhesive, photo-softening pressure sensitive adhesive, coating resin and novel photolithography materials.

It is known that the use of phosphonium salts as curing accelerators generally results in resin compositions with excellent latent properties. In this study, various phosphonium carboxylates, ammonium carboxylates, and 2-phenylimidazole were investigated as latent curing accelerators in the anionic polymerization of epoxy resin compositions, bismaleimide resin compositions, and bismaleimide-epoxy resin compositions. The latency of each curing accelerator was observed as follows ; pyromellitate dianion > 1,2-cyclohexanedicaboxylate monoanion > 1,4-cyclohexanedicaboxylate monoanion ≒laurate ≒ 2-phenylimidazole. It was also found that the cured epoxy resins containing phosphonium salts had higher heat resistance than those containing ammonium salts. These experimental results indicate that BTBP-pyromellitate and TBP-3S (both products of HOKKO CHEMICAL INDUSTRY CO.,LTD.) are the most promising curing accelerators that can achieve both the latency of resin compositions and the heat resistance of cured materials.

The physical properties of the crystalline cured polymer obtained by the reaction of the epoxy resin (DGBZP) having a benzophenone structure with 4,4'-dihydroxybenzophenone (DHBZP) were evaluated. The melting point (T_m) of the DGBZPcured product was 234.6℃, which was 56.7℃ higher than that of the epoxy resin (DGDPE) having a diphenylene ether structure, and Tg was also 43.3℃ higher than that of DGDPE. The coefficient of linear thermal expansion was 4.2 × 10-5 ℃ -1, which was significantly reduced by crystallization. Furthermore, it was confirmed that the thermal diffusivity had higher value up to around 230℃, corresponding to the Tm.

A huge amount of plastic production has been performed for a long time and has resulted in the accumulation of immense amount of litter in an environment. The plastic litter has been widespread in the oceans and has provoked microplastic (MP) pollution. A solution method of MP issue is a development of novel recycling process to produce additional value. We have succeeded in developing the value added recycling process for waterborne polyurethane, polypropylene and polystyrene with dormant bonds, which is produced by a photocatalyst and hindered amine light stabilizer combination. In this review, we discuss the novel recycling process.