The problems and cause analysis of calcium and zinc stabilizer in replacement of lead salt:
1. The product color is unstable;
2. It is easy to precipitate in the process of mouth mold production;
3. Yellow line and black line are easy to appear;
4. Poor color and aging resistance of the product;
Cause analysis of calcium and zinc deficiency:
(1) the processing scope is narrow, and the processing technology requirements should be strictly implemented. Compared with traditional composite lead thermal stabilizer, the long-term stability of calcium and zinc thermal stabilizer is still relatively poor, and the duration of processing is longer and yellow, and the sensitivity to process temperature is higher.
(2) with high volatile content, high melting point and low volatile lubricant are recommended in the formulation.
Compared with the traditional composite lead thermal stabilizer, the organic content of calcium and zinc thermal stabilizer is high, which can lead to a large precipitation, and the choice of lubricant is more prudent. Ester lubricant can effectively balance the fluidity and demodulation of plastic processing, and the production cycle is long and not easy to be precipitated, which can be widely used in the formulation of calcium and zinc stabilizers.
(3), calcium zinc stabilizer, in plasticizing process, because of its high electronegativity, polar groups and PVC resin polarity point has the certain affinity, can form a key strong combination, so as to eliminate or decrease the ionic bond appeal, PVC layers is PVC intertwine chain segment is easy to spread, the boundaries between molecular groups to hours, promote the plasticization of PVC resin. This results in the rapid increase of the melt pressure, the decrease of melt viscosity, the increase of temperature and the reduction of plasticizing temperature after the resin is plasticized in the feeding section. Resin transition plasticizing.
(4), calcium zinc stabilizer system with sufficient amount of lubricant can't in enough time to prevent further plasticizing resin, and destroyed the original lubricating balance, later use PVC melt in in the period of consume large amounts of heat stabilizer at the same time, and reach the ideal viscosity and elasticity, and can't meet the needs of the hard PVC production.
Therefore, in the production process of calcium and zinc system, it is recommended to use high melting point and low volatile lubricant in the formulation, otherwise the problems in production will continue. It is currently used in the process of general disease, the above Suggestions are only for reference.