Modification Of Calcium Carbonate And Its Influence On Polyurethane Thixotropic

There are many excellent characteristics polyurethane adhesive, were widely used in many areas of civil and industrial. In engineering requests was not only demanding high intensity adhesive bonding, also requires the project of good performance. In many requests, needs to be vertical or inclined surface sizing, which requires require curing adhesive at a size up to this time not drawing, not flowing, etc., which is claimed to have thixotropy. Calcium carbonate is a kind of low cost commonly used filler, calcium carbonate can be modified if the impact of modified polyurethane thixotropic calcium carbonate, and can reach a certain thixotropic result, in the actual request which will be immense significance process.This paper mainly include two aspects: researching MDI with TDI and polyether glycols PPG preparation prepolymer; calcium carbonate modify and using modified CaCO3 to prepolymer to thixotropic research characterize and discussion.A PU prepolymer synthesized with study, found that increasing the temperature of prepolymerization may accelerate the rate of prepolymerization, thereby curtailing time consumed prepolymerization reaction, so can improve efficiency; if by lower temperature, or by increasing the time for the prepolymerization reaction can complete, yet the efficiency will be low. Whether the reaction temperature is too high or the reaction time is longer would cause some side effects. Through experimental study, the optimal time in prepolymerization is about 2h, the optimal reaction temperature is 80 ?.CaCO3 was modified by stearic acid, titanate coupling agent, silane coupling agent(KH-570), maleic anhydride, 650 curing agent(low molecular weight polyamide), as well as methyl methacrylate(MMA) with KH570 copolymer(MMA-co-KH570),the study found that maleic anhydride and KH570 modified CaCO3 expressed hydrophilic, the drops were absorbed quickly, and the dispersion in polyurethane was not very well, didn`t display thixotropic performance, and the mechanical performance of polyurethane was similar to unmodified CaCO3. Stearin acid as well as titanate coupling agent modified CaCO3 showed good hydrophobicity, water contact angle approximated to 130 ° the sedimentation velocity was slow and the sedimentation volume was high, sedimentation values were 3.03,3.29 ml/g, can be dispersed in polyurethane very well, did not illustrate thixotropy, but the improvement of mechanical performance to polyurethane was better than unmodified CaCO3. The water contact angle of 650 curing agent modified CaCO3 was 56°, showed a weak polarityor, the sedimentation value was 1.0 ml/g. The dispersity in polyurethane was improved, and showed thixotropic performance when mixed with polyurethane. The water contact angel of MMA-co-KH570 modified CaCO3 was 60°, the sedimentation value was 1.36ml/g and showed a good dispersity in polyurethane. When mixed with polyurethane, manifested excellent thixotropic performance. Further more, the mechanical performance of polyurethane was better than unmodified CaCO3.