Preparation Of The Polyester For Epoxy/Polyester Powder Coating From Waste Polyester

At present, the polyester production of our country is nearly 5000kt/a ranking the top in the world. Calculating by 3%～5% waste material produced during manufacture, waste material is up to 100 kt every year. In addition, the packing materials of polyester nearly all become waste material after used. Therefore, the quantity of waste polyester in our country is very considerable. Therefore, it is valuable to develop polyester recycling industry for protecting environment.This thesis studied the PET alcoholysis process with the infrared and microwave as composite heat source. The influence of reaction condition on the alcoholysis product was investigated. The alcoholysis reaction and mechanism was researched preliminarily. Moreover, the effect of adipic acid, trimellitic anhydride, etc on esterification of the alcoholysis product was studied. In addition, relevant function tests of the obtained powder coating were carried on.Analyzing influence of microwave irradiation time and power, infrared time, material ratio on PET composite degradation, the order of the influence of four factors on the PET composite degradation was the microwave irradiation time >micro-wave power >infrared irradiation time > material ratio. The microwave irradiation time and microwave power were the main influence factors among them. Infrared irradiation time and material ratio were secondary influence factors. The best reaction condition was weight ratio of neopentyl glycol /PET 0.3, microwave power 528 W, infrared irradiation time 15 min, and microwave irradiation time 2 min, 1% ZnAc₂.Through the research on esterification reaction of alcoholysis product used for preparing epoxy/polyester powder coating, the best esterification reaction conditions were infrared preheat 5 min, 10% adipic acid, 10% trimellitic anhydride, microwave power 528 W. The obtained epoxy/polyester powder coating satisfied the ministry standards. The application of this project has already provided the newroute for the regeneration of the waste polyester and cheap raw materials for powder coating. Having the good society, economy and environmental protection benefit, it is significant to promoting the sustainable development of the polyester industry of our country.