| Based on the rule of the glycolysis reaction of recycled polyester,The waste PET was depolymerized using ethylene glycol in the presence of zinc acetate as a transesterification catalys,and obtained monomer bis(2-hydroxyethylene terephthala te)(BHET).By means of IR,GC we investigated the relationship between the monomer recovery rate and each of reaction time,pressure and temperature,and found out the optimized conditions of the reaction.Polyurethane adhesives are researched deeply and used wildly,The price of petroleum products is increasing dramatically nowadays with the decreasing of petroleum resource.Hence using waste PET resources such as degradation as a chemical raw material to produce Polyurethane adhesives has better environmental,economic and social benefits,especially reducesthe dependence on petrolin the world.The paper introduces the developing history and the current situation,expounds the theories of preparation and the process, and analyzes the research achievement.It includes,(I)The waste PET was depolymerized using ethylene glycol in the presence of zinc acetate as a transesterification catalys,and obtained monomer bis(2- hydroxyethylene terephthalate)(BHET).(II)the reaction of isocyanate group and hydroxyl group is the basilic reaction in the proparation,modification and curing process.(III)Component A containing -NCO was synthesized with PPG,MDI,the NCO content of the prepolymer was tested. component B containing -OH was gained by alcoholysis, esterification and condensation of waste polyester. The polyurethane adhesive was prepared by mixing component A and B. The synthesis processes of component A and B were discussed. The optimal conditions were gained as follows:component A prepared in a condition of T=80℃and t=3h;component B prepared at T(alcoholysis) =195-210℃,t(alcoholysis) =3.5h;T(esterification)=140-150℃,t(esterification)=60min;T(condensation)=190-210℃,t(condensation)=0.5h.(IV)The effects of the ratio of isocyanate,molecular weight of polyetherpolyol,reaction temperature on the viscosity are studied.Adhesion performances of polyurethane adhesives mentioned above are surveyed and evaluated.The performances of adhesives with different ratio of A component to B component were tested.The results showed could meet requirements of different operation were prepared by regulating ratio of A component to B component . The glass transition temperature(Tg)of cured adhesive film was -31℃.(V)adhesive bonding technology is explained,surface of the base materials should be treated. Solution of potassium hydroxide immersions is available to get rid of the PU-film. |
PDF Full Text Request