Synthesis And Application Of Environmentally Friendly Water-based Blocking Agents

At present,many construction projects have cracking pore leakage problems.With the continuous development of China’s construction industry,underground projects are also gradually increasing,and cracking inevitably occurs in the process of use.If there is a crack at the cable laying in the subway,it will lead to water in the middle joint of the cable and serious electric field distortion will occur,which will affect the subway operation.The current polyurethane grouting material on the market has problems such as low water package multiplier,long gel time,high solvent volatility and easy releasing.There is a need to develop a polyurethane sealer with high hydrophilicity,high water inclusion ratio,foamability,high reactivity and small shrinkage.In this paper,to solve the problems of water leakage and cable bundle insulation damage in underground projects,we developed an online monitoring device for humidity inside the cable insulation layer and developed hydrophilic polyurethane blocking materials.In analogy to the traditional moisture measurement method,the moisture-absorbing and exothermic properties of the moisture-sensitive detection layer are used to prepare a cable intermediate joint moisture warning device.When moisture enters the environment or the humidity increases,it can cause significant changes in the temperature detected by the reference temperature probe and the moisture-sensitive temperature probe.The environmentally friendly hydrophilic polyurethane blocking agents with different R-values and solvent additions were also prepared using toluene diisocyanate（PTDI）,diphenylmethane diisocyanate（MDI）,hydrophilic polyether polyol 8903,hydrophilic polyether polyol 4060,acetone and diethylene glycol dimethyl ether as the main raw materials,and the performance of the blocking agents was studied.Through molecular structure design,a polyether polyol with high hydrophilicity was tailored,which polyether polyol,with a functional degree of 4.5 and a molecular weight of 8000～10000.diisocyanate was subjected to addition polymerization reaction with hydrophilic polyether polyol to obtain hydrophilic polyurethane materials.The influence laws of R-value,solid content,raw material type and content variation on the properties of hydrophilic polyurethane materials such as flowability,gel time,foaming rate,water swelling rate and water coverage were investigated.The hydrophilic grout was prepared with PTDI as raw material and acetone as solvent.The results showed that the best performance of the slurry was produced when the NCO content of the system was 5%～8%,the amount of acetone was 15%～25%and the amount of catalyst was about 0.5%.Gel time,33～52 s;viscosity,694.49～1269.23 mPa·s;water inclusion multiplicity,33～38 times;foaming rate,507.28%～964.35%.Environmentally friendly waterborne polyurethane slurry materials were prepared by PTDI/MDI compounding with diethylene glycol dimethyl ether as solvent by prepolymerization method.The results showed that the slurry performance was optimal when R₁=1.6～1.8 and R₂=6～7.The gel time,39s～49s;foaming rate,422.64%～431.15%;water swelling rate,59%;water package multiplier,30～31 s;viscosity,751 mPa·s～864 mPa·s.And the solidification body shrinkage rate is small,no volatile gas release,and little harm to human body.