Chemicals and plastics have raised the quality of our life but also increased the emissions of greenhouse gas (GHG) connecting to the global warming and climate change in the world. It is crucial to meet market demands for industry while reducing the environmental load. 1,5-Pentamethylenediisocyanate (STABiO^TM PDI^TM) is a bio-based aliphatic diisocyanate and one of the candidate to create a sustainable industry. Using this unique isocyanate, we developed the various type of polyisocyanates, which had the characteristics such as “low viscosity”, “high solubility”,“water-dispersty” and “fast curing”.These bio-based polyisocyanates were superior to petroleum-based ones in reactivity, mechanical properties, chemical and water resistance. STABiO^TM PDI^TM has a possibility to meet both the performance to achieve the market needs and the reduction of the environmental load.

4-Ethylphenol (4-ep), pyrogallol (py) and catechin (ca) as the naturally derived phenol compounds were chemically introduced into kraft lignin under acidic condition to obtain the corresponding phenolized kraft lignins 4-ep-L, py-L and caL, respectively. Diglycidyl ether of bisphenol A (DGEBA) was then cured by using the phenolized lignins as curing agents and 1-cyanoethyl-2-ethyl-4-methylimidazole (2E4MZ-CN) as a curing accelerator, and as a result, BA/4-ep-L, BA/py-L and BA/ca-L were obtained as the cured products. BA/py-L and BA/ca-L showed glass transition temperatures (T_gs) above 200 °C, which are higher than that of the epoxy resin cured by the unmodified kraft lignin as a curing agent (BA/KrL). On the other hand, T_g of BA/4-ep-L was lower than that of BA/KrL. The results of dynamic viscoelastic measurements of the cured resins suggested that T_gs of the cured resins reflected their crosslink density and that higher T_gs of BA/py-L and BA/ca-L were derived from the introduction of the naturally derived phenols having multiple OH groups. The results of this study proved that the cured epoxy resins with both high biomass ratios and heat resistance could be prepared by introducing naturally derived polyphenols into kraft lignin.

It has been found that a crystalline cured polymer is obtained by the reaction of 4,4'-diglycidyloxybenzophenone(DGBP) and 4,4'-dihydroxybenzophenone (DHBP). In order to improve the heat resistance of the cured polymer, we examined the combined use of DHBP and 4,4'-diaminodiphenyl sulfone (DDS) as a curing agent. As a result, it was confirmed that the crystalline cured polymers were obtained up to 40 wt% of DDS in the curing agent. In the case of 40wt% of DDS, the glass transition temperature was 186.2℃, which was 20.7℃ higher than that of the cured product without DDS. Moreover, since the cured polymers have a crystal domain, the thermal conductivity was improved in addition to the reduction of the coefficient of thermal expansion and the water absorption.

It has been found that a crystalline cured polymer is obtained by the reaction of 4,4'-diglycidyloxybenzophenone(DGBP) and 4,4'-dihydroxybenzophenone (DHBP). In order to improve the heat resistance of the cured polymer, we examined the combined use of DHBP and 4,4'-diaminodiphenyl sulfone (DDS) as a curing agent. As a result, it was confirmed that the crystalline cured polymers were obtained up to 40 wt% of DDS in the curing agent. In the case of 40wt% of DDS, the glass transition temperature was 186.2℃, which was 20.7℃ higher than that of the cured product without DDS. Moreover, since the cured polymers have a crystal domain, the thermal conductivity was improved in addition to the reduction of the coefficient of thermal expansion and the water absorption.

The bismaleimide resins including the mesogenic group as thermal conductive moiety have been combined with the benzoxazine resin. The resins cured at 220℃ / 90 min have exhibited higher T_g (>200℃) than the operation temperature for the next generation power device and higher thermal conductivity (λ)(0.30－0.33 W/(m・K)) than the conventional epoxy resins (approx. 0.2 W/(m・K)). Furthermore, the composite with 60 vol% of boron nitride has provided not only high thermal conductivity (18.8 W/(m・K)) and thermal resistance but also high breakdown voltage (>60 kV). Therefore, the resin system is expected to be applied to the high heat release and insulating material for the next generation power module.

Electronic applications generally require products with low polarity and good dielectric properties. Materials that exhibit active crosslinking sites with the ability to form double bonds are chosen frequently for superior performance. In particular, materials thermally cured that form cross-linked vinyl units are most advantageous for dielectric properties.Products such as copper clad laminates (CCL) are actively being studied to better suit 5G and future 6G technology.Communication devices, such as cell towers, require CCL with high performance, usually selecting compounds that can ensure high crosslinking density. Polybutadiene with a high level of 1, 2-vinyl units in the molecular chain are commonly used in these applications. This high-vinyl technology can also be applied to Styrene－Butadiene－Styrene, or, 1,2-SBS.Additional studies are underway for most effective heat curing methods and additives to complete these functions. In this paper, we analyze CCL raw materials and explain these effects through actual examples of these materials.