With the development of new technology, the production of nylon 6 has stepped into the ranks of large-scale high-new technologies. According to the different use, the polymerization process of nylon 6 can be divided into the following ones.
This method is composed of two polymerization methods, namely pre-polymerization and post-polymerization methods, which is usually used in the production of industrial cord fabric with high viscosity. The two polymerization methods are divided into pre-polymerization pressurization and post-polymerization decompression. In the production process, pressurization or decompression treatment is carried out according to the comparison of polymerization time, individual in the product and low-poly volume. In general, the post-polymerization decompression method is better, but it requires more investment, and a higher cost, followed by high pressure and normal pressure in terms of cost. However, the operation cost of this method is lower. In the pre-polymerization pressurization and post-polymerization decompression production methods, during the pressurization stage, the ingredients of the production are mixed up and then all put into the reactor, and then the water-unlocking ring reaction and partial polymerization reaction are carried out at a specific temperature. The process is an endothermic reaction. The heat is located on the upper part of the polymer tube. During the pressurization process, the polymer stays in the polymer tube for a period of time and then enters into the polymerizer, where the viscosity of the polymer produced will reach about 1.7.
This method is used for the production of the domestic ribbon of nylon 6. Features: Larger continuous polymerization is adopted with a temperature of up to 260℃ and a polymerization time for 20 hours. The remaining oligomer in the section is obtained when the hot water goes against the current. DCS distribution system control and ammonia gas air drying are also adopted. The process of monomer recovery adopts the technologies of continuous three-effect evaporation and concentration and discontinuous distillation and concentration of the extracted water. Advantages of the method: Excellent continuous performance of production, high output, high product quality, small area occupied in the production process. The method is a relatively typical technology in the production of the current domestic ribbon.
It is widely used in the production of small-batch engineering plastics. The production scale is 10 to 12t/d; The output of a single autoclave is 2t/batch. In general, the pressure in the production process is 0.7 to 0.8mpa, and the viscosity can reach 4.0, and 3.8 at a normal time. That's because if the viscosity is too high, the output will be relatively low. It can be used to produce pa 6 or pa 66. The method has a simple production process, which is easy to change varieties and flexible for production.