Polytetrafluoroethylene (PTFE) is a high-performance fluoroplastic with excellent chemical resistance, high temperature resistance, low temperature resistance, abrasion resistance, non-adhesion and other characteristics, which is widely used in the fields of chemical industry, machinery, electronics, medicine and so on. In the field of raw materials for chemical production, the manufacturing methods of PTFE mainly include suspension polymerization, emulsion polymerization and solution polymerization. This article will introduce the manufacturing method of polytetrafluoroethylene in detail.
I. Suspension polymerization
Suspension polymerization is one of the most commonly used methods for the preparation of polytetrafluoroethylene. The principle of this method is to polytetrafluoroethylene monomer (TFE) in aqueous media, through the role of the initiator, free radical polymerization reaction to generate polytetrafluoroethylene particles. Polytetrafluoroethylene produced by suspension polymerization has the advantages of uniform particle size, smooth surface, high density and so on. The process of suspension polymerization mainly includes monomer preparation, initiator preparation, polymerization reaction, maturation, washing, drying and other steps. Specific operation steps are as follows:
1. Monomer preparation: add a certain amount of TFE monomer into the reactor, and add a certain amount of deionized water and dispersant, stirring well.
2. Initiator preparation: add the initiator into the appropriate amount of deionized water, stir well.
3. Polymerization reaction: add the initiator solution to the monomer solution, stir well, and then pass oxygen to carry out free radical polymerization reaction. During the reaction process, the reaction temperature and pressure need to be controlled, while maintaining the stirring speed to ensure that the resulting polymer particles are uniform in size.
4. Cooking: After the reaction, leave the mixture in the reactor for a period of time to allow the unreacted monomer to volatilize.
5. Washing: The cooked polymer particles are washed several times with deionized water to remove residual dispersant and unreacted monomers.
6. Drying: The washed polymer particles are dried to obtain the final PTFE product.
II. Emulsion polymerization
Emulsion polymerization is to add TFE monomer and water, emulsifier, etc. together into the reactor, through the action of the initiator, the emulsion is formed under the action of the emulsifier, and then the polymerization reaction is carried out to prepare polytetrafluoroethylene. Polytetrafluoroethylene produced by emulsion polymerization has the advantages of small particle size, uniform distribution and high surface activity. The process of
emulsion polymerization mainly includes the steps of monomer preparation, emulsifier preparation, initiator preparation, polymerization reaction, emulsion breaking, washing and drying. The specific operation steps are as follows:
1. Monomer preparation: add a certain amount of TFE monomer into the reactor, and at the same time, add a certain amount of water and emulsifier, and stir well.
2. Emulsifier preparation: add the emulsifier to the appropriate amount of water and mix well.
3. Initiator preparation: add the initiator to the appropriate amount of water and mix well.
4. Polymerization reaction: Add the initiator solution into the monomer emulsion and start the polymerization reaction. The reaction temperature and stirring speed need to be controlled to ensure that the resulting polymer particles are of uniform size.
5. Emulsion Breaking: At the end of the reaction, an emulsion breaker is added to break the emulsion and the polymer particles precipitate.
6. Washing: The precipitate is washed several times with deionized water to remove residual emulsifier and unreacted monomer.
7. Drying: The washed polymer particles are dried to obtain the final PTFE product.
Three, solution polymerization
Solution polymerization is the TFE monomer and initiator added to organic solvents, polymerization reaction to generate polytetrafluoroethylene a method. Polytetrafluoroethylene produced by solution polymerization has the advantages of high molecular weight and narrow molecular weight distribution, but the production cost is higher. The process of
solution polymerization mainly includes monomer preparation, initiator preparation, polymerization reaction, precipitation, washing, drying and other steps. Specific operation steps are as follows:
1. Monomer preparation: add a certain amount of TFE monomer into the organic solvent and mix well.
2. initiator preparation: add the initiator to the appropriate amount of organic solvent, stirring evenly.
3. Polymerization reaction: Add the initiator solution to the monomer solution and start the polymerization reaction. The reaction temperature and stirring speed need to be controlled during the reaction to ensure that the molecular weight of the polymer generated is evenly distributed.
4. Precipitation: At the end of the reaction, the polymer solution is added to a large amount of deionized water to precipitate the polymer.
5. Washing: The precipitate is washed several times with deionized water to remove residual organic solvents and unreacted monomers.
6. Drying: The washed polymer particles are dried to obtain the final PTFE product.
In short, there are several main manufacturing methods for PTFE, such as suspension polymerization, emulsion polymerization and solution polymerization. Different methods have different advantages and disadvantages and scope of application, choose the suitable method for production according to the specific production needs and conditions.
