Stability Of Isocyanate Research Articles

Synthesis of isocyanate microcapsules as functional crosslinking agent for wood adhesive

ABSTRACT In this study, controlled-release isocyanate microcapsules were synthesized as functional crosslinking to slowdown the rate of cross-linking reactions. The isocyanate microcapsules were prepared by In-situ polymerization with polymethylene polyphenyl polyisocyanates (PAPI) as core and Urea formaldehyde resin as shell in oil-in-water emulsions. The particle size distribution, chemical structure, morphology, activity, and stability of the microcapsules were comprehensively characterized. Finally, the microcapsules were applied in a wood adhesive to prepare water-resistant plywood. The results showed that the size of the microcapsules was around 100 μm, the active content of NCO was about 23.5%, and the core content was approximately 80%. Compared with the stability of the bulk isocyanate, the stability of the isocyanate in microcapsules was significantly improved in the wood adhesive system. Furthermore, the isocyanate microcapsules showed highly efficient in plywood at different time, which indicated that isocyanate microcapsules could be controllable released in plywood applications.

ポリウレタン ＩＩ ポリウレタンウレアの合成反応および副反応の解析

Reaction conditions giving linear prepolymers and polyurethaneureas which have less branching were investigated. The content of the main bonds such as allophanates and biurets formed by side reactions in the preparation of prepolymer were measured.The stability of isocyanates in dimethylacetamide is lower than that in bulk, therefore the bulk method is preferable for preparation of prepolymers.Reaction of n-butylphenylurea with phenylisocyanate was studied as a model reaction of biuret bond formation, and the rate constant was high enough to make branch in polymerization.From the results of solvent extraction tests, it was supposed that polyurethaneureas have large composition distribution.