The Synthesis, Modification And Properties Of Waterborne Polyurethane Adhesive

Waterborne polyurethane is that polyurethane dissolves in water or disperse in water to form a binary colloidal system. It is non-toxic, not pollute the environment, flammable, energy saving, easy to be processed. And it also has many performances, such as high adhesive strength, better solvent resistance and so on. It is more and more important in recently, and has been widely used in painting, interior parts bonding, fabric bonding and other fields.Different hard segment anionic waterborne polyurethane prepolymers are synthesized by two steps from isophorone diisocyanate(IPDI)/toluene diisocyanate(TDI).-NCO content is analyzed through the quantitative and qualitative analysis method. And the performance for waterborne polyurethanes also be studied.The cationic waterborne polyurethane prepolymers is synthesized by two steps from isophorone diisocyanate(IPDI). This cationic waterborne polyurethane has cation group on the skeleton. The experimental results show that solvent resistance, tensile strength and thermal decomposition temperature of cationic waterborne polyurethane are all better than those of anionic waterborne polyurethane.The anionic/cationic waterborne polyurethanes modified by acrylates(MMA, MA, EA, BA) are synthesized by isophorone diisocyanate(IPDI), polyester polyol(N210), dimethlolpropionic acid (DMPA)/N-methyl diethanolamine(MDEA),βhydroxyethyl meth acrylate(HEMA) as bridging, AIBN as initiator, then anionic or cationic waterborne polyurethanes are obtained through acrylates and polyurethanes by free radical polymerization, The structure and properties of WPU productions are characterized by FTIR, particle size analyzer and viscometer. The experimental results show that with the increasing of acrylates monomer content, the viscosity of anionic and cationic waterborne polyurethanes are all decreased, average particle size of anionic and cationic waterborne polyurethanes are all increased, solvent resistance strengthened. The anionic and cationic waterborne polyurethanes emulsions are more stable, transparent when the contents of acrylates are 6.0%and 8.0%respectively; The tensile strength are 4.71 MPa and 13.48 MPa respectively; The thermal decomposition temperatures can be to 306.1℃and 322.5℃respectively. The integral performances of cationic waterborne polyurethanes modified by acrylates which are better than anionic waterborne polyurethanes modified by acrylates synthesized in such way.A series excellent anionic and cationic waterborne polyurethanes composite latex are modified by acrylates(MMA, MA, EA, BA) and epoxy resin. Firstly, epoxy resin opened the ring and cross-linked with polyurethane prepolymer, then polymeried with acrylates in which HEMA as bridging, waterborne polyurethane adhesive co-modified by epoxy and acrylates were obtained. The experimental results show that with the increasing of epoxy content, water-resistant and solvent resistance of anionic and cationic waterborne polyurethanes are modified by epoxy and acrylates films are all strengthened; the viscosity increased, average particle size increased; tensile strength increased. The anionic and cationic waterborne polyurethanes emulsions are more stable, transparent when the contents of epoxy resin are all 4.0%; Water absorption and the inhalation of HCl, NaOH rates were 18.38%,16.20%, 54.70%and 5.68%,15.01%,3.98%; Viscosity are 800 mPa·s and 425 mPa-s respectively; Tensile strength are 7.53 MPa and 16.74 MPa respectively; The thermal decomposition temperatures can be to 330.3℃and 302.8℃respectively; The integral performances of cationic waterborne polyurethanes modified by epoxy and acrylates are better than anionic waterborne polyurethanes modified by epoxy and acrylates.