The Industrialization And Application Of Non-Toxic Polyurethane Curing Agent With High-Solid Content

Toluene diisocyanate(TDI) and trimethylolpropane(TMP)-based polyurethaneprepolymer is widely used as the curing agent in the preparation of high performancetwo-component coatings. The unreacted TDI from the agent is highly poisonous and must beremoved away as much as possible. The main contents of this thesis are as follows, the designof the industrial production line，the installation and optimization and improvement of theequipment, the separation of the free TDI, the analysis of the final product’s properties and theapplication of the products.An annual output of10,000tons of non-toxic industrial grade polyurethane curing agentproduction line is designed. Equipments and piping lines are determined.The design resultcome as follows, the volume of dehydration tank is4m3，the reactor is18m3, the intermediateproduct tank is20m3, the diluted tank is6m3, the area of the first-stage condenser is5.22m2and the second-stage condenser is3.55m2, the amount of chilled water which the condensersare needed is1468.7kg·min-1(87.4kg·min-1for the first stage,59.47kg·min-1for the second),the entire steam consume pey day of the production line is9392.8kg.The process parameters of the second separation column affecting the product qualitieswere analysed．The resuct show that the optimal feed rate is30kg·min-1, secondary distillationtemperature is190℃, secondary separation degree of vacuum is60Pa, scraping plank speed is180r/min.The automation control program has been used in the industrial production line, whichsolves the problems such as the high labor costs and feed instability. The change of separationcolumn help to solve the outlet blocking problem in the bottom, the change of scraping planklet it operate much more fluently than before. The transformation of the reactor cooling pipessolves the problem of the dropping temperature which is difficult to control in hot summer.The addition of a condenser to the vacuum unit to recycle the solvent make the solventrecovery rate improved from98.24%to99.78%. The renovation of steam pipe on recovery ofcondensed water cost saving about60,000yuan per year.Comparing the self-made product G21M to different kinds of other curing agent, testingthe main index, the results show that G21M is similar to the Bayer L75.They both producthave low free TDI content, high solid content and high efficient NCO value, good storagestability. Generally, there is no difference between G21M and Bayer L75on compatibility,glossiness, fullness in the compounding paint test, they are better than other curing agentswhich use the catalytic method. In opposite side, the hardness is a little lower and drying rate is a little slower than that of other curing agents. The mixing of the W950M with G21M in therate of20:80can get the films withs the best combination properties.Through the work above, the high solid content and, nontoxic qualified polyurethanecuring agents are produced on the industrial production line, and the products have beenapplied very well.