Research On Preparation Of Coated Poly-α-olefin Microencapsulation Based On Polyurethane

Drag reducing polymer microencapsulation are drag reducing polymer particles on the surface of which there is a layer material by physical, chemical or mechanical methods. The aim of microencapsulation is that avoiding the adhesion of particles and producing particles which can be stably stored in room temperature or when the particles are scattered as slurry. The drag reducing polymer microencapsulation belongs to the domain of Gel chemistry, and it involves the surface characters of particles, the surface interaction between particle and liquid; and the same time, microencapsulating needs the theory guidance of high molecular chemistry and physics and so on; In addition, with the industrial application of drag reducing polymer microencapsulation, technological process must be designed and it must be optimized flowed by the theory of chemical engineering. Because of the importance of drag reducing agent (DRA) in oil transportation industry and the problems in producing, storage and transportation of DRA, it is imperative that enforcing surface modification of drag reducing polymer particles.It analyzed the surface characters and chemical structure of drag reducing polymer particles; It pointed out the porous characters and molecular structure of long chain with multiple branched chains, this was the main reason that caused the adhesion of drag reducing polymer particles; It analyzed the wall materials and methods of drag reducing polymer microencapsulation.With polyurethane as wall material, the preparation technology and process of microcapsule coating were studied on the surface of poly-α-olefin viscoelastic polymer particles. Molecular dynamics simulation methods were used to discuss the relevant molecular designs, and stable performance polyurethane microcapsules were produced by the method of interfacial polymerization, with toluene 2,4-diisocyanate (TDI) and glycerol as active monomers. We researched the influence on coating in monomer type, ratio, particle size and amount of wall material, tested and analyzed the surface morphology, oil solubility, heat and pressure resistance of poly-α-olefin microcapsules, and evaluated the influences of drag reduction effect by the indoor simulative loop evaluation system for oil drag reduction agent. The results show that the length and number of branched chains had specific requirements in the design of coated wall material moleculars. The reasonable process conditions of polyurethane-coated poly-a-olefin microcapsules were as follows:the system was aqueous solution, the molar ratio of isocyanate group (-NCO) and hydroxyl (-OH) was 1:1, the mesh number of poly-a-olefin particle size was 60～80 (250～180um), the weight of wall material accounted for 0.5% of poly-α-olefin particles, the weight of surfactant accounted for 0.1% of poly-a-olefin particles, the temperature was 25℃under atmospheric pressure. The producing poly-a-olefin microcapsule had good surface morphology, faster release speed, no effect on the original drag reduction, excellent heat and pressure resistance. Moreover, poly-a-olefin microcapsules which were stored in powder-like solid at room temperature can be made into oil drag reduction agent easily at the time of on-site using by being dispersed into the solvent directly and solved the technical problem of dispersion in industrial applications.One-step method was used for industrial scaling-up, and the elementary industry product of drag reducing polymer microcapsules was obtained. The quality of this product met the design requirements. The microcapsules production could be stored for long time. The microcapsules produced by urea-formaldehyde polymerizing method were prepared into alcohol-based and water-based slurries. The slurries were contrasted with slurry which was prepared with drag reducing polymer particles that were not coated, and the themo-stability of the former are better than that of the latter.