The first stage is the earliest use of disc polymerization, that is, the mixed polymerization reaction liquid is placed in a stainless steel plate, and then these stainless steel plates are pushed into the heat preservation drying room. After several hours of polymerization, they are pushed out from the drying room and gathered with a trowel. The acrylamide is cut into strips, granulated by a meat grinder, dried in a drying room, and pulverized to obtain a finished product. This process is entirely hand-worked.
In the second stage, a kneading machine is used, in which the mixed polymerization reaction liquid is heated in a kneader. After the polymerization starts, the kneading machine is started, and the polymerization is carried out while kneading. After the polymerization is completed, the granulation is also substantially completed, and the poured material is dried. And smashed the finished product.
The third stage was the development of a conical kettle polymerization process in the late 1980s, which was successfully commissioned by the Jiangsu Jiangdu Chemical Plant. The process has a rotating cutter at the lower part of the conical kettle, and the polymer is granulated while being extruded, and dried by a drum dryer to pulverize the product.
In order to prevent the polyacrylamide rubber block from adhering to the wall of the polymerization vessel, some techniques use a polymer compound of fluorine or silicon to coat the inner wall of the polymerization vessel, but the coating layer is easy to fall off during the production process and contaminate the polymerization. Acrylamide products.
At present, the polyacrylamide production technology at home and abroad is basically similar to the third stage mentioned above, except that there are some differences in the equipment: the size and type of the polymerization tank (there are fixed cones and rotatable cones, after the polymerization is completed). , the polymerizer is inverted to pour the polyacrylamide rubber block), the granulation method (the mechanical granulation, the cutting granulation, the wet granulation, that is, the granulation in the dispersion), the drying method (there is a through-flow rotary drying, there are also Vibrating fluidized bed drying) and pulverization. Some of these differences are in the quality of the equipment, and some are the oil differences in the specific way, but in general, the polymerization technology tends to be fixed cone-shaped polymerization, vibrating fluidized bed drying technology.
Polyacrylamide production technology in addition to the above unit operation, there are obvious differences in the process formula, such as the current production process of ultra-high molecular weight polyacrylamide production, also low temperature initiation, there is pre-alkali co-hydrolysis The process and the post-alkali hydrolysis process are different. Both methods have advantages and disadvantages. The process of pre-alkali co-hydrolysis is simple, but there is a problem that hydrolysis and heat transfer are easy to cause cross-linking and loss of relative molecular mass, and then post-alkali hydrolysis. Although the process is increased, the hydrolysis is not easy to produce cross-linking, and the relative molecular mass loss of the product is not large.
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