Preparation method of ptfe dispersion resin with core-shell structure

A preparation method of a polytetrafluoroethylene (PTFE) dispersion resin with a core-shell structure, comprising the following steps:

• (1) stage I:
• adding water to a polymerization reactor, adding a fluorine-containing hydrocarbon nucleating agent, a fluorine-containing modifying monomer, a stabilizer, and a non-perfluorooctanoic acid (non-PFOA) surfactant in sequence, and then introducing a TFE monomer to form a solution;
• heating the solution to a reaction temperature, and dispersing the solution with stirring, then adding an initiator to start a polymerization reaction;
• emptying and replacing the unreacted monomer and modifying monomer in the polymerization reactor to remove the fluorine-containing modifying monomer to complete the reaction in a nucleating stage;
• (2) stage II:
• adding the tetrafluoroethylene (TFE) monomer to a certain pressure to enter a homopolymerization reaction in a growth stage, and adding the same or different non-PFOA surfactant at this stage to stabilize the dispersion, and keeping the reaction pressure constant by further adding the TFE;
• (3) stage III:
• adding a chain transfer agent or adding the fluorine-containing modifying monomer at the same time to continue the reaction until the end of the reaction;
• and
• (4) cooling the dispersion to remove the stabilizer and then carrying out post-treatment to obtain the PTFE dispersion resin;
• wherein the non-PFOA surfactant is one or more of a fluoroether acid or salt, a fluoroether sulfonic acid or salt, a fluoropolyether carboxylic acid or salt, a fluoropolyether sulfonic acid or salt, a hydrofluoroalkyl carboxylic acid or salt, a hydrofluoroalkyl sulfonic acid or salt, and a hydrocarbon-containing surfactant.