Wearable device products are evolving into devices in which people wear electronics like clothing-type devices.Pliable electronic circuit material with low rigidity and elasticity are required for the devices that have excellent wearing comfortableness and high affinity. This paper introduces the characteristics required for pliable electronic circuit material and gives multiple examples of the development of material based on not only urethane resin and silicone resin known as soft resin materials, but also acrylic resin and epoxy resin. In particular, we introduce an example of development that achieved both the characteristics of conventional resins and stretchability by applying a slide-ring polymer to the chemical crosslinking site of epoxy resin, which is widely used as a circuit board material. In addition, we also introduce examples of the application of various resin-based materials to devices.

The addition of phenol novolac (PN) was investigated to introduce a crosslinking structure into the crystalline polymer obtained from the reaction of 4,4'-diglycidyloxydiphenylether (DGDE) with 4,4'-dihydroxybiphenyl. As a result, the crystalline structure was maintained up to 60 wt% of PN in the curing agent, and the T_g increased. When 30 wt% of PN was used as the curing agent, the T_g increased by 12.1℃ compared with the polymer without PN, the thermal conductivity increased by about 30%, and the water absorption decreased by about 50% compared with the cured polymer from DGDE and PN.

BisB/Glu and BisB/Form novolac resins, which consist of bisphenol B (BisB) with a methyl propylidene group as a phenol (PhOH) component, glutaraldehyde (Glu) or formaldehyde (Form) as a crosslinking agent, have high level satisfactory properties of both flexibility and drawing ability as photoresist resins. On the other hand, dissolving rate for alkaline aqueous solution (DR) decreased with the increase of the mole ratio of the crosslinking agent, although the M_w change of both novolac resins was poor, regardless of the increase or decrease of the mole ratio of BisB and the crosslinking agent.In the reaction system in which the charged molar ratio of the crosslinking agent is high, the condensation reaction becomes difficult to progress by the steric hindrance of the methyl propylidene group of the BisB component, and the alkyl hydroxyl group proportion increases in the resulting molecule. Therefore, the structural analysis by MALDI TOF-MS measurement revealed that DR reduction occurred in spite of no significant change in M_w.

Without using fossil resources such as petroleum and coal, which are likely to be depleted and have a large load on the environment, we studied the improvement of performance of phenolic resin using lignin-based natural material, which is a non-fossil resource that is less likely to cause environmental problems. Polyethylene glycol-modified lignin developed by Forestry and Forest Products Research Institute was combined with phenolic resin to produce molding compounds and moldings containing modified lignin. As a result, it was found that the modified lignin phenolic resin is excellent in moldability, heat resistance, mechanical strength, and electrical insulation, and can achieve both heat resistance and flexibility.

Acrylic Adhesives composed of trialkyl borane (R₃B) complex are used to adhere to difficult-to-bond surfaces of adherends such as polyolefins. The main factor of high adhesive strength is thought that the polymer grafting from the substrate surface of the adherend contributes to the improvement of the interfacial adhesive strength. To improve the share strength and to extend the working time, other method that halogenated metals (MX_n) are added to the adhesives has been proposed and has been already an important technique to acrylic adhesives compound of R₃B complex or partially oxidated R₃B. In this research, we investigate the effect of MX_n on the adhesion in detail and uncover that chain transfer agents (CTA) with thiocarbonyl groups have same effect as MX_n. The reason of this effect is assumed that MX_n or CTA reacts with propagating radical to give dormant species and the deactivation of propagating radical including terminating step and trapping by oxygen could be suppressed.