Preparation method of synthetic resin

Synthetic resin is a type of artificially synthesized high molecular weight polymer that combines or exceeds the inherent properties of natural resins. The most important application of synthetic resin is in the production of plastics.
Preparation method
Synthetic resin is a polymer compound produced by combining low molecular weight raw materials such as monomers (such as ethylene, propylene, vinyl chloride, etc.) through polymerization reactions to form large molecules. The common polymerization methods in industry include bulk polymerization, suspension polymerization, lotion polymerization, solution polymerization, slurry polymerization, gas phase polymerization, etc. The raw materials for producing synthetic resins are abundant. In the early days, coal tar products and calcium carbide were the main sources, but now petroleum and natural gas products are mostly used.
Common aggregation methods in industry
Ontology aggregation
Definition: Ontology polymerization is the polymerization process of monomers under the action of initiators or heat, light, or radiation, without the addition of other media.
Features: The product is pure and does not require complex separation or purification. It is easy to operate and has a high utilization rate of production equipment. It can directly produce high-quality products such as pipes and plates, so it is also known as block polymerization.
Disadvantages: The viscosity of the material increases continuously with the progress of the polymerization reaction, making mixing and heat transfer difficult, and the reactor temperature is difficult to control.
Applicable scenarios: Production of resin such as poly (methyl methacrylate) (commonly known as organic glass), polystyrene, low-density polyethylene, polypropylene, polyester, and polyamide.
Suspension polymerization
Definition: Suspension polymerization refers to the polymerization process in which monomers are dispersed into droplets under the action of mechanical stirring or oscillation and dispersants, usually suspended in water. Therefore, it is also known as bead polymerization.
Characteristics: There is a large amount of water in the reactor, the material viscosity is low, and it is easy to transfer heat and control; After polymerization, resin products can be obtained through simple processes such as separation, washing, and drying, and can be directly used for molding and processing; The product is relatively pure and uniform.
Disadvantages: The production capacity and product purity of the reactor are not as good as those of the bulk polymerization method, and continuous production cannot be used.
Applicable scenarios: Suspension polymerization is widely used in industry.
Lotion polymerization
Definition: lotion polymerization refers to the polymerization of monomers forming lotion in water under mechanical agitation or vibration with the help of emulsifiers. The product of lotion polymerization reaction is latex, which can be directly used or destroyed, and can be washed, dried and other post-treatment processes to obtain powdery or needle shaped polymers.
Features: lotion polymerization can obtain high molecular weight polymer at a high reaction rate. The viscosity of the material is low, easy to heat transfer and mix, easy to control production, and easy to remove residual monomer.
Disadvantages: Emulsifiers added during the polymerization process affect the performance of the product. To obtain solid polymers, processes such as coagulation, separation, and washing are used. The production capacity of the reactor is lower than that of the bulk polymerization method.Solution polymerization
Definition: Solution polymerization is carried out in the presence of a solvent that can dissolve both monomers and polymers. During the polymerization process, the system forms a uniform viscous solution, and the polymerization system always remains homogeneous, with a long continuous operation cycle and easy operation.
Characteristics: Homogeneous reactions are easy to control, and molecular weight and its distribution can also be appropriately controlled.
Disadvantages: The solution polymerization system is viscous, causing difficulties and non-uniformity in heat and mass transfer.
Slurry polymerization
Definition: When slurry polymerization is carried out, a solvent or monomer itself is used as the dispersing medium, and the resulting polymer is insoluble in the dispersing medium and dispersed in particles, forming a slurry. Some previous literature attributed it to heterogeneous solution polymerization.
Characteristics: The system has low viscosity, is easy to stir, has easy heat dissipation, can use high monomer concentration, and improves unit equipment productivity.
Applicable scenarios: This method can be used for the production of high-density polyethylene, polypropylene, and other materials.
Gas-phase polymerization
Definition: During gas-phase polymerization, the gas-phase monomer and catalyst are introduced into the reactor in a specified amount for one-step synthesis to obtain a dry polymer. The premise of gas-phase polymerization is that the catalyst selectivity and yield must be sufficiently high, and the obtained product does not need to remove residual catalyst, which can greatly shorten the process. With the emergence of highly active carrier Ziegler catalysts, gas-phase polymerization has become mainstream in the production of polyethylene or polypropylene. In addition, it can also be widely used for polymerization based on free radical mechanism.