Preparation And Properties Of Self-crosslinking Fluorinated Acrylate Modified Waterborne Polyurethane Emulsion

Fluorine-containing acrylate modified polyurethane emulsion (FPUA) not onlyhas the excellent properties of polyurethane as flexibility, stretchability and goodadhesion to base material, but also has the outstanding properties inherited frompolyacrylate as good weather resistance, glossiness and mechanical strength. Besidesthat, FPUA has enhanced characteristics as water resistance, water and oil repellency,stain resistance and decreased surface energy because of the existence of fluorinesegment. Therefore, the research and industrialization of FPUA have aroused widelyconcern and already become hot current topics in the field.An aqueous dispersion of polyurethane with unsaturated bond and the ability ofself-emulsifying was synthesized by isophorone diisocyanate (IPDI), polyester dibasicalcohol (Mn=1500), dimethylol propionic acid (DMPA), hydroxyethyl methacrylate(HEMA), et al. Acrylate modified waterborne polyurethane emulsion (PUA) wassynthesized by the combination of the acrylic monomers by adding dropwise and theaqueous dispersion of polyurethane in the way of seminal emulsion polymerization.The self-crosslinking acrylate modified polyurethane emulsion was prepared by theintroduction of DAAM/ADH which could cause self-crosslinking at room temperature.The structure and the surface morphology of the PUA film were studied by FT-IR,particle size distribution and SEM. The optimal contents of PUA are that DMPA=5%,TMP=1%, hard segment=50%, R(-NCO/-OH)=1.3, MMA=35%, DAAM=2~3%,DAAM/ADH=1.25, and the properties are that good freeze-thaw and alcoholresistance abilities, the particle size of emulsion, water absorption, adhesion, hardness,dent resistance, tensile strength, elongation at break of the film and water contactangle were112.2nm,13.53%,0, HB,50kg/cm2,13.03Mpa/cm2,432%and71°respectively in this situation.Based on the self-crosslinking acrylate modified polyurethane emulsion, theself-crosslinking fluorine-containing acrylate modified waterborne polyurethane emulsion (FPUA) was synthesized by utilizing fluorine-containing acrylic monomersto modify the unsaturated bond of polyurethane aqueous dispersion in the way ofseminal emulsion polymerization. The structure and properties of the FPUA film werestudied by FT-IR, particle size distribution and SEM, proving the introduction offluorine-containing chain segment and investigating the surface enriched structuralmorphology of FPUA. The properties of emulsion stability, particle size, contactangle and water absorption of the film were investigated. The result indicated thatFPUA has the best comprehensive performance when the proportion of fluorinatedacrylate and methyl methacrylate are10%and25%. The particle size of emulsion,water contact angle, water absorption and hardness of the film are103.2nm,108°,10.19%and B.The analysis and comparison of the results of SEM and FT-IR show that thefluorine-containing chain segment migrated to the surface of the film and enriched init through introducing fluorinated acrylate. The comparison of the properties of filmsshow that the introduction of fluorine-containing chain segment decreases the surfaceenergy significantly and improves the water resistance effectively, the contact angleof the film increases from71°to108°and the water absorption decreases from13.53%to10.19%at the same time. The particle size of emulsion decreases from112.2nm to103.2nm and the hardness decreases from HB to B by introducingfluorinated acrylate.