1,Because PVC structure contains double bonds, branching points, and initiator residues, etc., heating to 100 degree C that is accompanied by dehydrogenation chloride reaction degradation, in the processing temperature (170 degree C or higher), the degradation reaction is accelerated, rapid cross-linking of macromolecules, decomposition occurs.
2, polyvinyl chloride (PVC) resin is extremely sensitive to heat, when the temperature reaches 90 degree C or more, a slight thermal decomposition will occur, 120 degree C or more will be obvious thermal decomposition, so that the colour of PVC resin gradually deepen until black. The physical properties of the product will also decline and gradually lose its value.
3, PVC resin moulding processing temperature is relatively high, generally at 170 degrees above. Processing temperature and decomposition temperature does not match, in order to ensure the processing performance of the product, need to add additives to inhibit the decomposition of polyvinyl chloride.
4, The definition of heat stabilization: broadly speaking, where to improve the thermal stability of polymers for the purpose of adding substances, become heat stabilizers.
1, and the unstable groups of PVC resin reaction, the generation of stable groups; such as fatty acid salts of ester group instead of allyl chloride.
2, and the thermal decomposition of PVC to produce a lively free radical reaction, terminate the free radical chain reaction; such as with the decomposition of PVC produced by the conjugated polythene sequence addition reaction, blocking its further growth and shorten the conjugated polythene chain segment, reduce its colouring properties.
3, and PVC resin decomposition of HCL reaction to generate harmless substances; such as alkaline earth metal soap and HCL reaction will be converted to alkaline earth metal chloride.
1, lead salt stabilizer
Advantages: thermal stability, especially good long-term thermal conductivity; good electrical insulation.
2, organotin stabilizers:
3, calcium and zinc environmental stabiliser advantages:
1）Excellent initial colouring and excellent long-lasting heat stabilizer.
(2) Anti-aging properties, excellent weathering properties, can give products good physical properties and comprehensive performance.
(3) High quality without impurities, good compatibility with resin, high fluidity performance, easy to disperse, wide applicability.
(4) Safety and environmental protection, in line with the EU REACH, ROSH requirements, does not contain lead, cadmium, barium and other harmful heavy metals and bisphenol A, nonylphenol, phthalates, polycyclic aromatic hydrocarbons, dimethyl fumarate and other harmful substances.
5）Excellent moulding and processing performance, good lubrication performance.
6) Cost-effective. The product takes calcium salt and zinc salt as the main body, and cooperates with organic auxiliary stabilizers to enhance the thermal stability performance and improve the processing performance.
