When selecting antioxidants and light stabilizers, the types of antioxidants and light stabilizers should be comprehensively determined according to the type, model, processing equipment and process conditions of the plastic material, the variety and amount of other chemical additives, the use environment and life of the product, and other factors. The selection of industrial antioxidants and light stabilizers should basically refer to the following principles.
One is mobility.
Plastic products, especially opaque products with a relatively small surface area to volume ratio (or weight ratio), the oxidation reaction mainly occurs on the surface of the product, which requires antioxidants and light stabilizers to continuously transfer from the interior of the plastic product to the surface of the product, thereby Play a role. However, if the migration speed on the surface of the product is too fast and the amount of migration is too large, the antioxidant and light stabilizer will volatilize into the environment on the surface of the product, or diffuse into other media in contact with the surface of the product and cause losses. It is practically unavoidable and should be considered when designing the formulation.
The second is compatibility.
The polymers of plastic polymers are usually non-polar, while the polymers of antioxidants and light stabilizers have different degrees of polarity and poor compatibility. Usually, antioxidants and photostabilizers are combined with polymer melt at high temperature, and the molecules of antioxidants and photostabilizers are accommodated between polymer molecules when the polymer is solidified. Within the dosage range of the formulation, special attention should be paid to the melting of antioxidants and light stabilizers at the processing temperature.
The third is processability.
During the processing of plastic products, adding antioxidants and light stabilizers can change the melt viscosity and screw torque of the resin. If the melting point of the antioxidant and light stabilizer is very different from the melting range of the resin, the phenomenon of anti-oxidant, light stabilizer bias or screw holding will occur. When the melting point of the antioxidant and light stabilizer is lower than the processing temperature by 100°C or more, the antioxidant and light stabilizer should be produced into a certain concentration of masterbatch, and then mixed with the resin.
The fourth is stability.
Antioxidants and light stabilizers should remain stable in plastic materials, have little volatilization loss in the use environment and high-temperature processing, do not change color or develop color, do not decompose (except for antioxidants with thermal stability), and do not mix with other additives Adverse chemical reactions occur, do not corrode mechanical equipment, and are not easily extracted by other substances on the product surface. Anti-amine light stabilizers are generally low-alkaline chemicals. When anti-amines are selected as light stabilizers in plastic materials, the prescription should not contain other acidic additives, and the corresponding plastic products should not be used in acidic environments.
In chemical production and processing, the importance of correct selection of antioxidants and light stabilizers is self-evident, but in addition to brand and model, product quality is also very important. Once you buy inferior products, it will have a great impact on the effect. Therefore, when purchasing antioxidants and light stabilizers, you must choose regular platforms and honest manufacturers
