Preparation method of ultra-high molecular weight anionic polyacrylamide

Abstract

The invention relates to a preparation method of ultra-high molecular weight anionic polyacrylamide, belonging to the technical field of compound preparation. The preparation method comprises the following steps of preparing deionized water, an acrylamide water solution, a hydrolyzing agent, a cosolvent and a chain transfer agent into a polymerization system; besides, compounding two azo initiators with different decomposition temperatures, and decomposing the two azo initiators at the lower temperature. According to a triggered polymerization process, the polymerization reaction is stable, the initiation efficiency is high, the defects that the consumption speed is too high caused by the single azo initiator, and the reaction is incomplete caused when the free radicals of the initiator are consumed off in a later period of the reaction, so that the polymer molecular weight is lowered are effectively overcome, and the ultra-high molecular weight anionic polyacrylamide having the molecular weight more than or equal to 350 million is prepared. The product is suitable for polymer flooding of tertiary oil recovery of an oil field, sewage treatment flocculants and papermaking, spinning and printing-dyeing industries.

Description

technical field [0001] The invention relates to a preparation method of ultra-high molecular weight anionic polyacrylamide, which belongs to the technical field of polymer compound preparation. Background technique [0002] As a water-soluble polymer product, anionic polyacrylamide has been widely used in polymer flooding, sewage treatment, papermaking, textile, printing and dyeing industries in the oil recovery industry. In oil extraction, especially in the stage of tertiary oil recovery, high molecular weight anionic polyacrylamide is used to add the treated produced water, and then re-inject into the ground together to play the role of "oil displacement", which greatly improves oil recovery. output. Moreover, the higher the molecular weight of the polyacrylamide used, the better the "oil displacement" effect. At present, there is an urgent need for a large amount of polyacrylamide with a molecular weight of more than 30 million for tertiary oil recovery. The preparatio...

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Problems solved by technology

[0006] The second is to add alkali and other additives to the acrylamide aqueous solution, and then add a composite initiator composed of a redox initiator and an azo initiator at an initiation temperature of 5 to 30°C to initiate polymerization to obtain polyacrylamide. In this method, the polymerization is first initiated by a low-temperature redox initiator, and after the temperature of the polymerization system reaches the decomposition temperature of the azo initiator, the azo initiator continues to initiate the reaction polymerization, but this method cannot obtain products with a molecular weight of more than 30 million

[0007] Chinese patent CN 101649024 discloses a preparation method of high molecular weight polyacrylamide dry powder. In the polymerization of acrylamide aqueous solution, a ternary composite initiator is used, and an azo initiator such as azobisisobutylamidine hydrochloride is added before the reaction , the temperature of the system is controlled at 35°C to 40°C, and redox initiators and various additives are added to carry out adiabatic polymerization. The operation process is cumbersome, and finally a product with a molecular weight of 23 million is obtained.

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