Polyacrylamide production is carried out by using acrylamide aqueous solution as raw material and polymerization reaction under the action of initiator. After the reaction is completed, polyacrylamide rubber block is cut, granulated, dried and pulverized to obtain polyacrylamide product. . The key process is polymerization, and mechanical degradation, thermal degradation and cross-linking should be paid attention to during the subsequent treatment to ensure the relative molecular mass and water solubility of polyacrylamide.
Polyacrylamide + water → polyacrylamide rubber block → granulation → drying → pulverization → polyacrylamide product
China's polyacrylamide production technology has probably gone through three stages:
The first stage: the earliest use of disc polymerization, that is, the mixed polymerization reaction liquid is placed in a stainless steel pan, and then these stainless steel discs 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 was cut into strips and granulated by a meat grinder. The drying room is dried and pulverized to obtain a finished product. This process is entirely hand-worked.
The second stage is to use a kneading machine to heat the mixed polymerization reaction solution 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 basically completed, and the material is poured out. The product is dried and pulverized.
The third stage: In the late 1980s, the conical tank polymerization process was developed, which was successfully tested by the Jiangsu Jiangdu Chemical Plant. The process comprises preheating and mixing the polymerization reaction liquid in a conical kettle, and after passing through the nitrogen gas, the material is extruded by air, and the lower part of the conical kettle is provided with a rotating cutter for the material, and the polymer is extruded while being extruded. It is granulated, dried by a drum drying agent, and pulverized to obtain a 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 polypropylene. Amide product.
At present, the polyacrylamide production technology at home and abroad is basically similar to the third stage described above, but there are some differences in the equipment: the size and type of the polymerization tank (there are fixed cones and rotatable cones, and the polymerization is completed). After that, the polymerizer is inverted to pour the polyacrylamide rubber block, and the granulation method (the mechanical granulation, the cutting granulation, the wet granulation, that is, the granulation in the dispersion), and the drying method (there is a through-flow rotary drying, It also uses vibrating fluidized bed drying and pulverization. Some of these differences are in the quality of the equipment, and some are different in the specific way. In general, the polymerization technology tends to be fixed cone-shaped polymerization, vibrating fluidized bed drying technology.
