Recycling Of Anti-br Printed Circuit Boards By Vacuum Pyrolysis And Research Of Kinetics Mechanism

As the widely used of anti-Br epoxy resin in printed circuit boards （PCB）industry, the production Numbers of anti-Br epoxy resin have been increasingyear by year. The studies on resource recycling of anti-Br PCB are importantmatters. How to maximize the recycling efficiency, how to minimize theenvironmental problems caused in recycling process, and the characteristics ofanti-Br epoxy resin in recycling process, those are all have great significancesto resource saving and environmental protection.In order to recycling and reuse the nonmetal part of anti-Br PCB moreeffectively, vacuum pyrolysis technology was researched here. The substrate ofanti-Br PCB was pyrolysis under vacuum condition. Three aspects were mainlyinvestigated in vacuum pyrolysis process: pyrolysis characteristics, kineticsparameters and mechanism; influence factors and the best pyrolysis conditions;product composition and characteristics.In the first, the paper used thermo-gravimetric analysis method, pyrolysis characteristics of anti-Br PCB were researched under argon （Ar） atmosphere.The influence of pyrolysis heating rate was determined. Flynn-Wall-Ozawamethod and Friedman-Reich-Levi method were both used in research of kineticparameters. The result showed that there are three different pyrolysis reactionstages, the activation energy of three stages were147.377kJ·mol^-1,174.206kJ·mol^-1and161.575kJ·mol^-1, respectively. The order of pyrolysis reaction was2.32. By establishing the kinetics model, determined the kinetics mechanismequations of anti-Br printed circuit boards made epoxy resin.Anti-Br PCB was thermally decomposed under vacuum condition in alaboratory-scale sealed tubular oven. Every important factor influencing thedistribution of pyrolysis products were researched, and the vacuum pyrolysisoptimum condition of anti-Br printed circuit boards made epoxy resin wasdetermined. The results of orthogonal experiment indicated that the finaltemperature was the most important factor, vacuum conditions was moreadvantageous to the pyrolysis reaction compared with atmospheric conditions.The optimum condition of vacuum pyrolysis was obtained as follows: finaltemperature a t550℃-650℃, vacuu m degree of10kPa, heating r ate of10℃·min^-1-15℃·min^-1, holding time of50min, condensing temperature at-20℃.The liquid pyrolysis products were analyzed by element analysis, fouriertransform infrared analysis （FT-IR）, chromatography-mass spectrometry analysis （GC-MS）. The major products in the oil were phenol （23.918%）,2-methylphenol （8.205%）, bisphenol A （6.253%）, and various substitutedphenol. Through the contrasted with oil of atmospheric conditions and oil ofvacuum conditions, organics have the higher recycling use value just likephenols were produced greater in vacuum conditions than atmosphericconditions. It embodied the superiority of vacuum pyrolysis.