Wood-based epoxy resins were synthesized from resorcinol-liquefied wood, which is the resin precursor, and the adhesive properties of the resins were evaluated. In case using steel plates as the adhesive substrates, the wood-based epoxy resin had lower tensile-shear adhesive strength than bisphenol-A type epoxy resin. However, in case using plywood as the substrates, the shear adhesive strength of wood-based epoxy resin indicated twice as high as that of bisphenol-A type epoxy resin. The observation of the fractured surfaces revealed that the main mode was the failure of the plywood substrates, which means the excellent adhesive properties of the wood-based epoxy to biomass substrates. As an application of the good affinity to biomass materials, the wood-based epoxy resin was served as the matrix resin for flax fiber reinforced composites. From the fractured surfaces of the composites, the good adhesive properties of the wood-based epoxy resins to plant fibers were confirmed, which would be a clue for the creation of high performance biomass composites.

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Several types of pressure sensitive adhesives (PSA) were prepared by mixing the emulsion of an acrylic base polymer and the emulsified rosin-based tackifier in varying ratios. After they were adhered on stainless steel plates, and then stored at different temperature, the critical surface tensions (γc) of them were measured with time in the following methods. Two kinds of liquids (water and dipropylene glycohol) having different surface tensions were mixed in varying ratios, and surface tensions of each solution were measured. Then, these solutions were contacted on the surface of PSA to observe the contact angle. Finally γc was calculated on the basis of the contact angles through Zisman-plot. γc of the PSA without tackifier tended to increase remarkably with time, especially for the high temperature storage condition. The PSA containing tackifier which were stored at 23℃ gave substantially constant γc regardless of storage time. In contrast, when they stored at 70℃, γc increased. The results indicated the possible convergence of γc on about 22mN/m irrespective of the concentration of tackifier in PSA. Moreover, it was suggested that critical surface tension also became higher linearly with an increase in the concentration of tackifier on surface layer.The driving force of migration of tackifier toward the surface of PSA was induced by the minimization of the interfacial surface free energy between the PSA and the adherend.

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Using acetoacetylated (AA) PVA with various degrees of acetoacetylation and ordinary partially saponified PVA, the following facts were obtained as the result of examining the reactivity with an added isocyanate compound (pMDI) in AA PVA aqueous solution and the formation of crosslinking by heat treatment as compared with ordinary PVA.1) The rate of consuming NCO groups in the PVA aqueous solution was higher with AA PVA than with ordinary PVA. The reactivity of the AA group in AA PVA for the NCO group in pMDI was higher than that of the OH group.2) The E' value in the rubbery flat region of AA PVA was higher than that for ordinary PVA as a result of measurement of the dynamic viscoelasticity of cured films, and the temperature of the E" shoulder based on the glass transition of AA PVA was higher than that for ordinary PVA.3) The crosslinking density of PVA, which was calculated from the E' value of the rubber flat region of the cured film, increased with the degree of acetoacetylation.4) The AA PVA film cured at 120℃ for 2 hours showed a significantly decreased water solubility.5) The ability of the PVA aqueous solution to bond wood improved by the addition of pMDI. Curing at 120℃ resulted in superior waterproof adhesion for AA PVA.

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