Preparation Of Self-Extinction Waterborne Polyurethane Resin

In recent years,matte materials have been pursued by people,and the preparation of matte waterborne polyurethane resin has become a research hotspot.Low gloss products on the market at present the main method of adding matting agent by physical extinction performance,and this kind of method for the stability of the product and product has great effect on other properties,since the extinction type water-borne polyurethane resin can avoid physical methods of defects,but currently the extinction of water-borne polyurethane resin extinction performance deficiencies,poor product stability were the problem.In view of the problems existing in the preparation of self-extinction waterborne polyurethane,this paper adopts two methods to prepare self-extinction waterborne polyurethane.The first method starts from the raw material of the preparation of waterborne polyurethane,using mixed isocyanate HDI/IPDI as the hard segment and mixed polyol PTMG/PCL as the soft segment to prepare large particle size self-extinction waterborne polyurethane resin.The influencing factors of its preparation were studied systematically.The second method was to prepare self-extinction waterborne polyurethane/nano-SiO₂ composite resin by sol-gel method.Specific research contents were as follows:（1）With mixed HDI/IPDI,mixed PTMG/PCL,hydrophilic chain extender DMPA,neutralizer TEA and post-chain extender IPDA as main raw materials,a series of emulsions were prepared by prepolymer method,and self-extinction waterborne polyurethane resin was successfully prepared.The results showed that with the increase of n（HDI/IPDI）,the particle size of the emulsion increased,the stability gradually decreased,the adhesion increased,the gloss of the film decreased first and then increased,and the water absorption decreased.With the increase of n（PTMG/PCL）,the particle size of the emulsion decreased,the stability improved,the adhesion weakened,the gloss of the film decreased first and then increased,and the water absorption increased.With the increase of DMPA dosage,the particle size of the emulsion decreases,the stability increases,the gloss of the film increases,and the water absorption increases.The change of neutralization degree mainly affects the stability of emulsion.With the increase of neutralization degree,the water absorption rate of film increases,and the gloss increased slowly.With the increase of R,the particle size of the emulsion increased,the stability decreased,the adhesion weakened,and the gloss and water absorption of the film decreased.With the increase of chain extension coefficient,the particle size of emulsion gradually increases.Under the same chain extension coefficient,diethylenetriamine（DETA）had the largest particle size and the lowest gloss,while ethylenediamine（EDA）had the smallest particle size and the highest gloss.The results showed that when n（HDI/IPDI）was 1:1,n（PTMG/PCL）was 1:4,DMPA dosage was 2.7%,neutralization degree was 100%,R value was 1.25～1.35,chain extender was DETA and chain extender coefficient was 0.45,the emulsion particle size could reach about 800nm,and the emulsion had good stability.After film formation,the microscopic surface was rough,and the luster of 60°could reach below 5,which could meet the requirements of extinction.（2）The optimum prepolymerization temperature was determined to be 80℃,and the prepolymerization time was 2h.In the DMPA addition process,the particle size of the emulsion by one-step method was larger than that by two-step method,and the surface roughness of the film by SEM analysis was also higher than that by two-step method.At the same time,the one-step process was simpler and time-saving.In the neutralization process,the particle size of the post-neutralization emulsion was much larger than that of the pre-neutralization process,and the luster of the film was also lower,but the emulsion stability and film forming performance were poor,the film water absorption was high,and the actual operability is much lower than that of the pre-neutralization process.In the emulsification process,the positive phase dispersion requires higher formula,and the gloss of the film was also higher than that of the reverse phase dispersion method.The appropriate emulsification process was the reverse phase dispersion method,the emulsification temperature was 25～30℃,and the rate of adding water was about 260m L/min.In the chain extension process,the front chain extension had smaller emulsion particle size and lower surface roughness,the gloss of the film could reach 9.7,but the water absorption rate was the lowest 11%.The particle size of the synchronous chain extension emulsion was the largest,the surface of the film was irregular convex,and the gloss was 3.1,but the process was limited.After chain extension,the emulsion with moderate particle size could be obtained,and the film gloss could reach 1.8,and the process operation stability was high,which was the most suitable amine chain extension process.（3）Non-ionic polyol N-120 was introduced into HDI/IPDI-PTMG/PCL system as hydrophilic monomer.The results showed that with the increase of N-120 content,the particle size of emulsion decreased and the gloss of film increased.Through the comparative study of emulsion stability,it was found that nonionic emulsion has better acid and alkali resistance and medium stability than anionic emulsion.FT-IR analysis showed that the absorption peak of Si-O-Si appeared in the polyurethane,which indicated that WPU/SiO₂ composite emulsion was successfully prepared.The results of particle size,water absorption,contact angle,mechanics,glossiness and SEM show that the particle size of the composite emulsion can reach more than 1000nm,and WPU and SiO₂ were connected by APTES,which greatly improved their compatibility.Moreover,the mechanical properties and water resistance of the composite material with TEOS were improved,the surface roughness of the film was increased,and the glossiness of the film was decreased.When the dosage of APTES was 1.5%and TEOS was increased to 5.15%,the glossiness of the film reaches a minimum of 3.4.