Effect of the ethylene/vinyl acetate ratio of ethylene-vinyl acetate emulsion on the curing behavior of an emulsion polymer isocyanate adhesive for wood |
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| Authors: | Naruhito Hori Kentaro Asai Akio Takemura |
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| Institution: | (1) Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan |
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| Abstract: | We investigated the curing behavior of an emulsion polymer isocyanate adhesive for wood with different ethylene-vinyl acetate
(EVA) emulsions, because it was found that the ethylene/vinyl acetate weight composition (E/VA ratio) of EVA could control
the volume of gas emitted from the adhesive. EVA with higher VA content reduced the volume of gas emitted at the initial stage,
which was caused by the extent of the reaction between the NCO groups and water. The reaction scheme of NCO could not be determined
because the broad infrared (IR) absorptions due to CaCO3 and water masked the information of the NCO products in IR spectra.
Examination of the degree of swelling suggested that the adhesive films stored for 3 weeks had the same degree of cross-linking
structure in spite of the variation of EVA. This result was supported by IR spectroscopy, which showed the same amounts of
NCO remained in these films. All the adhesives prepared in this study had satisfactory bond performance. The findings indicate
that the E/VA ratio affects the curing behavior of the adhesive in the initial curing stage, whereas the cross-linking structure
and the bond performance were independent of the E/VA ratio after storage for 3 weeks.
Part of this report was presented at Wood Adhesives 2005, November 2–4 2005, San Diego, CA, USA |
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| Keywords: | Isocyanate Ethylene-vinyl acetate copolymer API EPI Wood adhesive |
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