| Polyurethane materials has been widely used because of their high strength, excellentflexibility, strong resistance to abrasion, resistance to solvent. But the production process ofsolvent-based polyurethane not only consumes huge quantities of solvent, but also causesharm to the environment and personal safety. Waterborne polyurethane (WPU) can becompared to solvent-based polyurethane in the performance, and has the advantage ofenvironmental protection. At present, IPDI, TDI and HMDI are mostly used in the synthesisof WPU. MDI is easy to buy and the price is relatively low. MDI-50can be stored and usedat room temperature, reducing the difficulty of synthesis of MDI-type WPU.The purpose of this study is to prepare MDI-type WPU, optimize the formulation andsynthesis process, study the performance.The main contents of this work include:1. MDI-type HTWPU was prepared by one step method. The reaction time wasdetermined by di-n-butylamine titration. The effects of R1value, EG amount,DMPA amount on the solid content of HTWPU emulsion were studied. The effectsof R1value, DMPA amount on the properties of HTWPU emulsion were alsostudied. The HTWPU was cured by waterborne blocked isocyanate curing agent.We studied the effect of R2value on the properties of the cured film.2. MDI-type one-component WPU was prepared by the prepolymer method. Theeffects of reaction temperature on the reaction rate, molecular weight anddistribution were studied by di-n-butylamine titration. The effects of R3value, R4value, carboxyl group content, TMP amount on the molecular weight anddistribution were also studied. We discussed the effects of R3value, carboxylgroup content, macromolecular diol type, TMP amount on the properties of theWPU emulsion and mechanical properties, hardness, water resistance of the curedfilm. The organo-sioxane was used to modify the WPU. The water resistance ofthe modified WPU with different amount of organo-sioxane were studied. |
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