Material Analysis
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Synergy and antagonism with hindered phenol antioxidants
Problem Phenomenon
When calcium-zinc stabilizers and hindered phenol antioxidants such as 1010 are used simultaneously in the formulation, the initial coloring is instead aggravated, the thermal stability time (Congo red method) is shortened by 20%, and the phenomenon of mutual interference between additives appears.
Cause Analysis
The quinone-type oxidation products generated by hindered phenol antioxidants at high temperatures have chromophoric groups that aggravate the product color; the oxidation products of hindered phenols are acidic and undergo neutralization reactions with alkaline metal soaps, consuming stabilizer components; the metal phenolates generated by the reaction of the two do not have thermal stabilization function and are colored substances; imbalanced ratios amplify the antagonistic effect.
Solution
Reduce the hindered phenol antioxidant dosage to 0.1-0.15 phr, which is only 1/3-1/2 of the conventional recommended amount; preferentially select phosphite-type antioxidants such as 168, PEPQ to replace part of the hindered phenols; increase the β-diketone auxiliary stabilizer amount by 0.2-0.3 phr to compensate for initial coloring; introduce organic auxiliary stabilizers such as uracil derivatives into the calcium-zinc stabilizer to reduce interaction with other additives.
Key Takeaway
The combination of calcium-zinc systems with antioxidants requires evaluation of synergistic/antagonistic effects; phosphite types are more suitable than hindered phenols for synergistic use with calcium-zinc stabilizers.
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