Synthesis Of Cyclohexanone-formaldehyderesin And Its Application In The Latent Curing Agent

Aldol condensation, oneofreactions whichincrease the length of carbon chain,can change twosimplemonomers intoa complexpolymer.Ketone aldehyde resins are akind of thermoplastic resins through aldol condensation between cyclohexanone andformaldehyde (CFR),it is usually used as a multifunctional additive, such as coating,inks and so on. Usually, CFR is synthesized under the role of alkali catalyst. As asolidbase catalyst,hydrotalcite-like compoundshavetunable lamellar structure and can beused in thealdolcondensation reactionwith easy separation and recovery. Moreover,the use of this catalyst can effectively avoidthe environmental problem because wastewater won’t produce during the reaction, therefore it is attracted more and moreattention.Besides, CFR was used to synthesis the ketamine whichwas so calledthesinglecomponent epoxyresin adhesive,it was believed that it had agood adhesion inthewaterand the wetcircumstances. It could expand the range of application of theepoxy resin adhesive andsimplify the methodof epoxy resin,this would have certainresearch significance. Therefore,there are two parts in this study:(1) Mg-Al hydrotalcite(HT) with Mg/Al molar ratios of3was prepared bythedecomposition of ureauniformcoprecipitation， the doublemetal compositeoxides(HT-c) was prepared by calcining of the HT, the reconstructedhydrotalcitecatalyst (HT-r)was obtained aftertheliquid phasehydration. HT, HT-c and HT-r werecharacterized by FT-IR, TEM and XRD, respectively.The experiment was discussedthealdol condensation of cyclohexanoneand formaldehyde was investigated usingHT-r asthe catalyst. The single-factor experimentsresults showedtheoptimization ofreaction conditions: under the conditions of8wt%catalyst and5.3wt%CTAB,75°Creaction temperature,20h reaction time, the yield of CFR reached66.61%.Reutilization and regeneration of the HT-rresults showed that: itshowed lowercatalyticactivity forthe HT-r directly usedinthe reactionagain, but whenit handled withcalcinations and hydration, to a certain extent, thereaction activitywould have recovery;(2)The curing agent ketimine was synthesized byCFRandamine(ethylenediamine,hexamethylenediamineandm-phenylenediamine),then it was characterizedwithaminevalue, and determined itsstorage period, tensile lap-shear strength andthe pencil testafter the epoxy resin cured by the latent curing agentketimine.The resultsshowedthat:the epoxy resin adhesive can select the curingtemperature (the adhesive whichneeded different curing temperaturecould be synthesized by differentamineintoketimine),and good storage performance, compared withthecuringagentketimineand the correspondingamine(hexamethylendiamineandm-phenylenediamine)in the same humid environmentcuredepoxy resin,the former one mechanical properties (tensile lap-shear strength andthepencil test have been improved.