Preparation And Modification Of Waterborne Polyurethane-acrylate Composite Emulsion

Polyurethane(PU)materials are widely used in coatings,adhesives,leather finishing agents,rubber and plastics owing to their high strength,good flexibility,wear resistance,good chemical resistance.In recent years,with the improvement of environmental laws and enhancement people’s environment awareness,developing low-toxic,environmental and energy-saving WPU material has become a research topic.However,the single component WPU materials are mostly linear thermoplastic polymer and lack cross-linking structure,so some inferior properties exist in their film,such as poor mechanical property and solvent resistance.Polyacrylate(PA)has good weather resistance,good hardness of film,excellent water and solvent resistance,so it is complimentary with PU in performance.Thus,acrylate modified PU was studied in this paper so as to get good-performance WPU materials.a emulsifier-free acrylate-modified aqueous polyurethane emulsion(HWPUA)was synthesized by in-situ polymerization.Based on it,ogranosilicon and epoxy acrylate was introduced to modify the HWPUA emulsion.The impact of the structure of HWPUA on its performance was studied,which provided the theoretical basis for the synthesis and modified research on polyurethane acrylate composite emulsion(WPUA).1)HWPUA emulsion was prepared using polyneopentytlene adipate glyeol(PNAL),hexamethylene diisocyanate(HDI),2,2-Bis(hydroxymethyl)propionic acid(DMPA),styrene(St),n-Butyl acrylate(BA)as the main raw materials,.The structure of product was characterized by FT-IR spectroscopy.It systematically studied the effect of PA content,quality ratio of St and BA,the initial molar ratio of the-NCO and-OH and the amount of DMPA on the properties of HWPUA.The results showed that when the PA quality score was 30%,the n(-NCO): n(-OH)was 6 : 1,w(DMPA)=6%,m(St): m(BA)=6 : 4,the HWPUA composite film showed a good water resistance and thermal resistance.Compared with the bibulous rate of 40.53% of the unmodified PU film,the water absorption of the HWPUA film was reduced by 51.89%,reaching to 19.5%.Microstructure and crystallinity of HWPUA film was studied by means of scanning electron microscopy(SEM)and X-ray diffraction(XRD).SEM reveal that the hard segment and soft segment of the polyurethane rank orderly and distribute evenly.With the introduction of acrylate,the surface of the filmbecomes rough,and the two-phase compatibility in the system increases.The diffractograms of PU and HWPUA have a large broad diffraction peak,indicating that no obvious crystallinity exists in any of the samples.Thermal performance analysis indicates that the thermal stability of PU is improved with the addition of the acrylate.2)The polyurethane seed emulsion was prepared by reacting the polyneopentytlene adipate glyeol(PNAL),hexamethylene diisocyanate(HDI),2,2-dimethylol propionic acid(DMPA),and trimethylolpropane(TMP).The prepolymer prepared by method of end capping with(3-aminopropyl)triethoxysilane(KH550)and 2-hydroxyethyl methacrylate(HEMA).The silicone modified HWPUA emulsion was obtained by adding styrene(St)and butyl acrylate(BA).The structure of the polymer was characterized by FT-IR.The particle size and morphology of the emulsion was characterized by DLS and TEM.The thermal stability of the composite film was determined by thermogravimetric analysis(TG).Crystallization performance was analyzed by XRD.The results show that the performance of HWPUA is enhanced obviously with the addition of KH550.When KH550 mass fraction is 5%,the film has excellent water resistance and thermal stability.3)G-HWPUA emulsion was synthesized by adding crosslinking monomer glycidyl methacrylate(GMA).The structure of G-HWPUA was characterized by FT-IR.The emulsion stability,thermoanalysis and water absorption test result show that: when the added amount of GMA is 27%,G-HWPUA has good storage stability,water resistance and thermal resistance.The minimal water absorption rate is 4.86%.