Research Of Waterborne Polyurethane Adhesive Modified By Butyl Acrylate/styrene And Hydroxylated Epoxy Soybean Oil

The solvent polyurethane adhesive, which was widely used in the laminated soft package films, was restricted because of its emission of volatile organic compound. Waterborne polyurethane adhesive overcame the shortcomings of solvent polyurethane adhesive, such as toxic, flammable, bad smell, environmental pollution, so it has been widely used in many fields. But the performance of single waterborne polyurethane adhesive was not very good, because of its poor wet ability on nonpolar substrate, low bonding strength, low initial tack, etc. In order to enlarge its application, waterborne polyurethane need to be modified.Epoxy soybean oil is an environmental friendly, good solvent resistance and renewable material, which can improve the adhesion strength and water resistance of polyurethane adhesive. Styrene has some advantages of high mechanical strength and water resistance, If the styrene used alone, its film was more brittle, this shortcoming will be improved by adding soft monomer, such as butyl acrylate.Waterborne polyurethane hybrid emulsions were prepared using polyether binary alcohol (N220), toluene diisocyanate (TDI) and dimethylol propionic acid (DMPA), and trimethylol-propane (TMP) as a internal cross-linker, hydroxylated epoxy soybean oil (HESO), styrene (St) and butyl acrylate (BA) as modification agents, in the help of diacetone acrylamide (DAAM). The high performance waterborne polyurethane adhesive was made by this hybrid emulsion by adding 0.3 wt% defoaming agent and 0.4 wt% wetting agent. The effects of total mole rate of NCO/OH, the contents of BA, St, TMP, HESO and DAAM on the properties of hybrid emulsion, water resistance and mechanical properties of film and adhesion properties were investigated. The experimental results showed when the total mole rate of NCO/OH was 1.1, the contents of DMPA, TMP and HESO were about 5.0 wt%,3.0 wt%, 6.0 wt% respectively, the content of BA/St was 28 wt%, and the styrene was 15 wt%, the properties of the emulsion were good, the adhesive made by the emulsion could meet the need in the laminated soft package films.The hybrid emulsions and films were characterized by Fourier Transform Infrared (FTIR), Particle Size Analyzer, Transmission Electron Microscopy (TEM), Atomic Force Microscope(AFM), and Differential Scanning Calorimetry (DSC). The testing experimental results showed that the properties of modified waterborne polyurethane were much better than thoes of single waterborne polyurethane. The adhesion mechanism was analyzed, it was found that the coordination bond theory and adsorption theory play a dominant role in the process of modified waterbrone polyurethane adhesive bonding the laminated soft package.