The production technology of polyacrylamide in my country has probably gone through 3 stages
The production technology of polyacrylamide in my country has probably gone through 3 stages
The first stage is to adopt disc polymerization in the early stage, that is, put the mixed polymerization reaction liquid in a stainless steel tray, and then push these stainless steel trays into an insulated drying room. After a few hours of polymerization, they are pushed out of the drying room and the polymer is put in with a guillotine. Acrylamide is cut into strips, granulated by a meat grinder, dried in a drying room, and crushed to obtain a finished product. This process is completely manual workshop style.
The second stage is to use a kneader, which is to put the mixed polymerization reaction liquid in the kneader and heat it. After the polymerization starts, start the kneader, and knead while polymerization. After the polymerization, the granulation is basically completed, and the poured material is dried. , Crushed to get finished products.
The third stage is that in the late 1980s, a conical kettle polymerization process was developed, which was successfully commissioned by the Jiangsu Jiangdu Chemical Plant of the Ministry of Nuclear Industry. The process has a material-making rotating knife in the lower part of the conical kettle. The polymer is granulated at the same time it is pressed out, dried by a drum dryer, and crushed to obtain a product.
In order to avoid the polyacrylamide glue sticking to the wall of the polymerization kettle, some technologies use fluorine or silicon polymer compounds to coat the inner wall of the polymerization kettle, but this coating layer is easy to fall off during the production process and contaminate the polymer. Acrylamide products.
At present, the production technology of polyacrylamide at home and abroad is basically similar to the above-mentioned third stage, but it is slightly different in equipment: the size and type of the polymerization kettle (there are fixed conical kettle and rotatable conical kettle, after the polymerization reaction is completed) , The polymerization kettle is turned upside down to pour out the polyacrylamide rubber block), granulation method (with mechanical granulation, cutting granulation, wet granulation or dispersion granulation), drying method (with through-flow rotary drying, there are also Dry with vibrating fluidized bed) and crushing method. Some of these differences are differences in equipment quality, and some are oil differences in the specific methods used, but in general, polymerization technology tends to be fixed conical kettle polymerization, vibrating fluidized bed drying technology.
In addition to the above unit operations, the polyacrylamide production technology has obvious differences in process formulations. For example, the current production process for producing ultra-high relative molecular weight polyacrylamide is also initiated at low temperature, and there is pre-alkali co-hydrolysis There are advantages and disadvantages of the process and the post-alkali and post-hydrolysis process. The pre-alkali co-hydrolysis process is simple, but there is the problem of crosslinking and relative molecular mass loss caused by heat transfer during hydrolysis. Although the technological process is increased, the hydrolysis is uniform and it is not easy to produce crosslinking, and the relative molecular mass loss of the product is not large.
