Study On Preparation Of Two-component Solvent-free Polyurethane Adhesive

Polyurethane adhesives are researched deeply and used wildly, of which Solvent-free ones meet the requirement of environment protection, represent the direction of polyurethane adhesive development. Especially the two-component solvent-free polyurethane adhesives have been a research focus for the long storage life, adjustable film hardness and the other excellent features.The paper introduces the developing history and the current situation, expounds the theories of preparation and the process, and analyzes the research achievement. It includes,(1) two-component solvent-free polyurethane adhesives of general purpose, two-component solvent-free polyurethane adhesives for building are prepared by MDI(4,4'-diphenylmethanediisocyanate), PPG (polyether polyol), MOCA(3,3'-dichloro-4,4'-diaminodiphenylmethane) , adopting simplified preparation technology. On this basis, polyurethane prepolymer is modified by epoxy resin (EP-51) and organ-siloxane(KH-550) respectively. The characters of IR spectrums show that organo-siloxane modified two-component solvent-free polyurethane adhesives and epoxy modified ones are prepared. DSC curves indicate the glass transition temperatures are -45.6℃, 36.1℃, -16.2℃and -45.9℃in turn to be mentioned.(2) the more cross linker, the shorter curing time. content of -NCO in polyurethane prepolymer has influence on bubbles, and the optimum content is 8wt% by test. Optimum range of epoxy resin(wt%)/-NCO(wt%) value is 0.993~1.027. The viscosity of the polyurethane prepolymer raises along with the organ-siloxane content increases, and the organ-siloxane content must be less than 1.9%.(3) tolerance time of two-component solvent-free polyurethane adhesives for building reaches 120h under the normal temperature. Immersion tests are carried under 100±1℃temperature. After soaking in the mineral oil for 168h, epoxy modified two-component solvent-free polyurethane adhesives'tensile shear strength is 1.83Mpa, and tensile shear strength change rate is 18.3%, while organo-siloxane modified ones'are 1.83Mpa and 18.3%.(4) adhesive bonding technology is explained, surface of the base materials should be treated. Solution of potassium hydroxide immersions is available to get rid of the PU-film.(5) antibacterial experiments are carried on and the results show that the PU films without antimicrobial can not inhibit the growth of escherichia coli.