The addition effect of phthalimide derivatives (PIDs) on curing reactions of epoxy resins by imidazoles was investigated. The curing behavior and storage stability of the epoxy compositions containing imidazoles and PIDs were evaluated. As a result, the curing initiation temperature in the presence of PIDs were higher than that in the absence of PIDs. Moreover, the storage stability increased by the utilization of PIDs. The UV-Vis absorption spectrum of a mixture of PIDs and imidazoles suggested that the charge transfer interaction, which led to decreasing the nucleophilicity of imidazoles, resulted in the thermal latency. The present study provides the charge transfer interaction between PIDs and imidazoles in epoxy resins, which can be used for the construction of thermal latent systems for curing reactions of epoxy resins.

An epoxy resin having a m-terphenyl structure (DGMTP) was synthesized and the physical properties of a cured polymer obtained by curing with 4,4'-dihydroxydiphenyl ether were evaluated. DGMTP gave a crystalline cured polymer with a melting point of 202.2℃, which was 14.8℃ higher than that of epoxy resin having a diphenylene ether structure. The thermal conductivity of crystalline DGMTP cured polymer was 0.31 W/m·K, which is about 1.5 times that of the amorphous cured polymer from bisphenol A type epoxy resin. In addition, the moisture absorption was reduced by about 50%.

We have reported that the application of thermal latent hardener with aliphatic amine structures to cyanate ester resin/epoxy resin provides rapid curing at low temperature of approximately 100 ℃, and the networked polymers have high physical properties and adhesive strength. In this study, we investigated the adhesive behavior, the coefficient of linear thermal expansion, and the volume change by networked polymers from the viewpoint of the curing reaction or crosslinked structure. As the result, it was found that the hydroxyl groups generated by the ring-opening reaction of the epoxide contributed to the high adhesive strength to the substrate. The rigid triazine structure by trimerization of cyanate esters caused to decrease the coefficient of linear thermal expansion and to increase the curing shrinkage.

As we proceeded with the development of a Novolac resin with flexibility and high lithography performance, we focused on adopting a linear polymer structure with few branched structures similar to a dry film resist. In our attempt to develop a flexible Novolac resin for resists, we found that BisC/Glu Novolac resins consisting of bisphenol C (BisC) and glutaraldehyde (Glu), which contain a bulky isopropylidene group in the molecular chain skeleton as a phenolic (PhOH) component, exhibited the highest flexibility and high drawing ability of 4 μm or less that we have investigated. In this study, BisB/Glu and BisB/Form Novolac resins using bisphenol B (BisB, 2,2-Bis(4-hydroxyphenyl)butane) with methylpropylidene group, effect on flexibility expression by alkyl side chain elongation in addition to bulkiness, were newly synthesized and their properties were investigated. The M_w of BisB/Glu and BisB/Form Novolac resins was about 3000－3300 and 1200－1900, respectively. The dissolving rate for alkaline aq. solution (DR) tended to decrease with increasing molar ratio of Glu and/or Form as a crosslinking agent. This is quite different from the correlation between M_w and DR observed in general Novolac resins. Among the obtained Novolac resins, a Novolac resin satisfying the condition DR ≦ 800 Å/sec was chosen, applied to a silicon wafer to obtain a resin film thickness of 1.5μm, and a resist pattern was prepared to evaluate drawing performance. It was confirmed from the bending test that BisB/Glu and BisB/Form Novolac resins showed high flexibility, especially BisB/Glu Novolac resin showed very high flexibility similar to BisC/Glu Novolac resin. Both Novolac resins exhibited high drawing ability (Patterning: 3 μm or less, residual membrane thickness: 90% or more), slightly exceeding the drawing ability of BisC/Glu Novolac resin.

There is growing social interest in bioplastics that contribute to the construction of a decarbonized and circulating society. This review describes the development trends of bioplastics and natural polymer-based materials. Bioplastics are divided into biomass plastics that reduce the use of depleting fossil resources and biodegradable plastics that are expected to reduce the environmental load at the time of disposal mainly due to the feature of the function of being decomposed by microorganisms. Poly(lactic acid) and microbially produced polyesters are classified as biodegradable biomass plastics.Recently, non-biodegradable biomass plastics such as bio-polyethylene have become widespread, and bioelastomers such as natural rubber and vegetable oil-based polymers have also been put into practical use. In addition, there have been active research for materials using polysaccharides such as cellulose and starch, which are non-plastic but contribute to decarbonization, and resin composite materials and reduced plastic model products have been developed.