> The main introduction and application of plastic heat stabilizer
The main introduction and application of plastic heat stabilizer
2014-02-14 by seoer8
Common composite plastic heat stabilizer [ 1 ] include : liquid barium heat stabilizer for panel complexes ; main component of non-toxic liquid calcium zinc stabilizers are calcium stearate, castor oil , calcium , zinc stearate, castor oil , zinc and epoxidized soybean oil , an ultraviolet absorber. Hugh liquid calcium zinc stabilizers are generally used more readily soluble in organic solvents carbon number less fat fat calcium and zinc ; liquid barium cadmium and liquid barium cadmium zinc composite authorized agent of such composite stabilizer is mainly used for soft PVC products processing .
PVC on the destruction process , various mechanisms have been proposed : Thermal oxidative decomposition ; absence of oxygen free radicals in a large increase crosslinking ; influence of tacticity to degradation ; photodegradation ; oxidation dehydrochlorination ; radiation degradation ; processing and the impact point of branching in the molecule of PVC degradation ; molecular chains due to the introduction of critical stress .
PVC from thermal decomposition of the heat sensitive part discharged HCL, PVC form double bonds in the structure , due to the high activity of propylene chloride , the reaction can be carried out continuously , continue to form a conjugated double bond , the heat stabilizer for panel structure becomes more olefins , causing coloring products .
When calcium zinc stabilizer compound , first, zinc soap enereplace chlorine in the same time, accompanied by the transfer of the double bond . Polyene structure is destroyed so that suppresses discoloration. However, zinc chloride will precipitate in PVC , HCL has a catalytic effect on the off , so that PVC is unstable , even blackening caused by bridging role . Calcium soaps through the metathesis reaction of the zinc soap in the PVC stabilization effect of the chlorine atoms of zinc chloride and then generate the production of zinc soap , which on the one hand the activation of the zinc soap , which on the one hand activated zinc soaps, hand and inhibits chloride damaging effects of zinc. A large number of organic products can greatly improve the initial coloring , it is also commonly used in the stabilizer to compensate for the lack of early calcium zinc stabilizers coloring .