Synthesis And Application Of Acrylic Modified Cationic Waterborne Polyurethane

In order to get higher performance of cationic waterborne polyurethane,this thesis firstly synthesized the cationic waterborne polyurethane by means of acetone method with 2,4-tolylene diisocyanate(TDI)and polytetramethyehydrofuran glycol(PTMG)as main raw materials,2-Butene-1,4-diol as small molecule chain-extender,N-methyl diethanolamine(MDEA)as hydrophilic chain-extender.The reaction process conditions for synthesizing waterborne polyurethane were discussed.The optimum conditions of the reaction were as follows:the molecular weight of PTMG was 1000;n-NCO/n-OH was 3:1,the reaction temperature for preparing prepolymer was 75?80 ? and reaction time was 3 hours,without adding any catalyst;the mass fraction of MDEA was 6-7%;the isocyanate index was about 1.2;the neutralization degree was 90%?100%.The obtained cationic waterborne polyurethane had the best storage stability and comprehensive performance.FT-IR indicated that the target product was obtained.With the purpose of enhancing the performance of WPU film,we added methyl methacrylate(MMA)to the WPU emulsion when conducted free radical polymerization in the absence of initiator,and had synthesized excellent polyurethane-acrylate copolymerization emulsion(WPUA)initially by this means.The optimum conditions of the polymerization were as follows:the polymerization temperature was 75?80 ?,polymerization time was 3.0?3.5 hour,the initiator dosage accounted for 5 ‰ of the total amount of monomer,and the amount of MMA was about 20%?30%.Compared with WPU:the water absorption of the film decreased from 35%to 12%;the hardness increased from B to H;the tensile strength increased from 24 MPa to 31 MPa;the elongation at break decreased from 475%to 556%;the average particle size increased from 95 nm to 223 nm.FT-IR indicated that the blend degree between molecular chains increased,the introduction of MMA reduced the micro-phase separation degree of soft segment and hard segment.TG results showed that the heat resistance of WPUA film improved.