Preparation of 4-dimethylaminopyridine-boron trifluoride complex type curing accelerator and its catalytic effect on epoxy curing
A complex type of curing accelerator(DMAP-BF)was prepared by using 4-dimethylaminopyridine(DMAP)and boron trifluoride-ether solution[BF3-O(C2H5)2]as the raw materials,and its chemical structure was characterized.The catalytic effects of this curing accelerator on the curing reaction of the ternary composite system(BF-1～BF-6)composed of biphenyl aromatic alkyl epoxy resin(NC3000),naphthalene-containing tetrafunctional epoxy resin(HP4700)and nitrogen-containing phenolic resin(PF8705)were systematically investigated.The research results showed that,(1)The expected product was successfully prepared by conducting infrared,nuclear magnetic,XRD,and microscopic morphology analysis on the curing accelerator and epoxy-phenolic aldehyde-curing accelerator premix.(2)The curing performance test results indicated that DMAP-BF could catalyze the curing reaction of epoxy-phenolic system and exhibited good thermal latency characteristics.DMAP-BF had a good catalytic effect on the curing of the epoxy-phenolic composite system mentioned above.The activation energy(Ea)of curing reaction of the BF-ref sample without DMAP-BF promoter was 109.4 kJ/mol higher than that of the BF-6 system[m(NC3000)∶m(HP4700)=50∶50].(3)The melt viscosity of the BF sample system in the temperature range of 100-140℃could be as low as 0.1 Pa∙s,but when the temperature reached the curing process temperature(175℃),DMAP-BF could catalyze the rapid curing of the epoxy-phenolic resin system.This characteristic was crucial for the practical application of DMAP-BF,as it could endow epoxy molding compound(EMC)with better storage stability and process performance.(4)The initial thermal decomposition temperature of BF series cured products was around 400℃,and the weight loss decreased after 500℃,indicating that BF composite cured products had good heat resistance stability and could meet the subsequent application requirements of EMC.
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