Several matters needing attention in the use of plastic additives
1. The compatibility of plastics additives with polymers.
If the compatibility is not good, the plastic additives are easy to precipitate out. The precipitation of solid plastic additives, commonly known as "spray frost"; Liquid plastic additives are precipitated out, known as "exudation" or "perspiration". Plasticizer loses the role of plastic additives after precipitation, and affects the appearance of plastic products. However, it should also be noted that for certain plastic additives, it does not require good compatibility with polymers. For example, the compatibility of lubricants should not be too large, or it will act as a plasticizer to soften the polymer.
The compatibility of plastics additives and polymers mainly depends on their structural similarity. For example, the polarity of the plasticizer in the polar polyvinyl chloride is more compatible than the polar weak. For example, the introduction of long chain alkyls in antioxidant and light stabilizers can improve their compatibility with polyolefin. For inorganic fillers and inorganic pigments, they are not soluble in polymer, but are dispersed in polymer. For this kind of plastic additives, they are required to have good dispersivity.
2. The mutual influence of plastic additives and polymers on stability.
Plastic additives must be stored permanently in plastic products. Therefore, attention should be paid to the mutual influence of plastic additives and polymers on stability. Some polymers, such as polyvinyl chloride, can break down some of the plastic additives. There are also some plastic additives that speed up the degradation of the polymer.
3. Durability of plastic additives.
The loss of plastic additives is mainly through three ways: volatilization, extraction and migration. The volatility depends on the structure of the plastic additives, for example, because the molecular weight of butyl phthalate is less than that of dioctyl phthalate, so the former is much more volatile than the latter. The extraction of plastic additives is directly related to the solubility in different media, and appropriate plastic additives should be selected according to the use environment of the products. Mobility refers to the transfer of plastic additives from the products to the adjacent objects, and the potential size of the plastic additives is related to the solubility of plastic additives in different polymers.
4. The adaptability of plastic additives to processing conditions.
The requirements of processing conditions for plastic additives are mainly heat resistance, which means that the plastic additives are not decomposed, volatile and sublimated at the processing temperature. At the same time, we should also pay attention to the corrosive effects of plastic additives on processing equipment and molds. The processing conditions of different polymers are different; The same polymer, due to different processing methods, may require different plastic additives. In conclusion, the selected plastic additives should be suitable for processing conditions.
5. The relationship between the use of products and the choice of plastic additives.
The important basis for choosing plastic additives is the ultimate use of the products. The products of different USES have certain requirements for the appearance, smell, durability, pollution, electrical performance, thermal performance, weather resistance and toxicity of the plastic additives.
The toxicity of plastic auxiliary problem has drawn widespread attention, especially the food and drug packaging materials, medical equipment, conduit, toys, plastic products health security problem is more and more attention by people. The plastic additives used in the above-mentioned plastic products are strictly stipulated in various countries.
6. The synergistic effect and phase resistance of the plastic additives.
In the same polymer in a variety of plastic additives, such as cooperate proper, often mutual synergy between plastic additives, the formula "synergy" polymer of one of the main purpose is to find synergies between the plastic additives. Of course, simplifying components and reducing costs are also the purpose of formulation research. Improper selection of the formula may lead to the "phase resistance" between the plastic additives, so it should be avoided. However, chemical changes and discoloration between different plastic additives should also be avoided.