PVC stabilizers|rare earth heat stabilizers mainly include organic weak acid salts and inorganic salts of light rare earth lanthanum, cerium and neodymium which are rich in resources. The types of organic weak acid salts include rare earth stearate, rare earth fatty acid, rare earth salicylate, rare earth citrate, rare earth laurate, and rare earth caprylate.
PVC stabilizer|The mechanism of action of rare earth stabilizer
1. The special electronic structure of rare earth lanthanides (2 electrons in the outermost layer, 8 electronic structures in the second outer layer, and many empty orbitals) is determined, and the energy level difference of the empty orbital is very small. Under the action of external thermal oxygen or in Under the action of the polar groups, the outer layer or sub-outer layer electrons are excited, can coordinate with the unstable Cl on the PVC chain, and can form coordination complexes with the hydrogen chloride decomposed during the PVC processing, and at the same time, the rare earth elements and There is a strong attraction between the chlorine elements, which can play a role in controlling the free chlorine elements, thereby preventing or delaying the automatic oxidation chain reaction of hydrogen chloride, and has a thermal stability effect.
2. The rare earth multifunctional stabilizer can physically adsorb the oxygen in PVC processing and the ionic impurities contained in the PVC itself, and enter the lattice cavity of the rare earth multifunctional stabilizer, avoiding their impact on the parent C—Cl bond vibration. Therefore, through the action of the rare earth multifunctional stabilizer, the activation energy of PVC removal of HCl can be increased, thereby delaying the thermal degradation of PVC plastic.
3. The appropriate anion group in the rare earth compound can replace the allyl chloride atom on the PVC macromolecule, eliminate this degradation weakness, and achieve the purpose of stability.
Generally speaking, the stabilizing effect of rare earth heat stabilizers is better than that of metal soap stabilizers, has better long-term thermal stability, and has extensive synergistic effects with other types of stabilizers, and has good tolerance. Sulfur pollution, stable storage, non-toxic and environmentally friendly. In addition, rare earth elements and CaCO3 have a unique coupling effect, and at the same time promote the plasticizing effect of PVC, which can increase the amount of CaCO3, reduce the use of processing aid ACR, and effectively reduce costs. The stabilizing effect of rare earth on PVC is characterized by its unique synergistic effect. Proper coordination of rare earths with certain metals, ligands and auxiliary stabilizers can greatly improve the stability.