What are Polymer Additives?
A large number of plastics have been developed and used as materials for our daily lives or industrial use, such as materials for the bumpers and interior parts of automobiles, electrical and electronic appliances, including televisions and cellular phones, and food containers and packaging.
In practical applications, most plastics contain many types of Polymer additives, each of which is added in a small amount. These polymer additives contribute to maintaining the functionality of the plastics or conferring new functionalities. Plastics inherently lack sufficient stability against heat and light. For this reason, plastics readily oxygenate and degrade when exposed to heat or ultraviolet rays in sunlight during the molding process or use. Such exposure impairs the inherent properties of the polymers and thus lowers the quality of the resulting products. For example, when materials are used at high temperature or exposed to sunlight, as in the case of automotive interior materials, they rapidly degrade during use. This kind of environment may discolor the polymer, impair its properties, and/or impair the durability that is required of a plastics.
In order to prevent this degradation, the addition of small amounts of stabilizers is more effective and economical than modifying the polymer itself. In practice, a large number of stabilizers have been developed, and these are selected and blended in accordance with the type or application of the relevant plastic; this has contributed to making plastic a wide spread material. For example, polypropylene is widely used in automobiles, home appliances, and convenience articles, but if polypropylene with no incorporated antioxidant is kept in an oven at 150℃, it oxygenates and degrades in 24 hours. In contrast, a polypropylene containing 0.4% antioxidant does not degrade even after 2,000 hours or longer, i.e. its lifetime is dramatically improved whilst still maintaining the inherent properties and characteristics of polypropylene.
As just described, polymer stabilizers, as exemplified by antioxidants, dramatically extend the lifetime of plastics even when added in small amounts, and they are therefore essential materials for plastics in practical applications.
However, in order to expand the range of applications in which polymers can be used, it is not enough for polymers merely to retain their original properties, as this still leaves them insufficient in many cases. By blending functionalizing additives into polymers in appropriate amounts, polymers can be given functions which they would otherwise not possess, this being achieved without any modification to the molecular design or polymerization conditions. Hence, functional additives enables the expanded applicability of plastic materials, thereby contributing to expansion of the range of applications for which plastics can be used. For example, polypropylene, which is translucent, exhibits dramatically improved transparency when 0.2% clarifying agent is blended into it, as shown in the photo on the right. Other examples of the many functional additives developed to date include flame retardants for making originally combustible plastics flameproof, plasticizers for imparting flexibility, antistatic agents for eliminating the negative effects caused by buildup of static electricity, and nucleating and clarifying agents.