The Category and Application of Plastic Additive for Plastic Film Processing

2013/05/31 plas.hc360.com

 

Plastic additive is the chemicals to improve the processability and usability of resin. There are more than ten kinds of normally used plastic additives, but with the increasing plastic variety, enlarging use, continuously improving process technology, the type and species of plastic additive also increase day by day.

Plastic additive is needed to be added in processing and using plastic film. The reason is that the property of some resin or film products cannot meet the requirement of processing technic, so adding plastic additives here is only to change their machinability. The processability of some materials is quite good, while product performance cannot meet the requirements. Here we also need to add additives to change the properties of products. Of course, these two effects are complementary to each other. Sometimes, we aim to reach both of the goals. Here introduce the additives which can change the usability of plastic packing film first.

General Requirement for Additives

Generally speaking, only good consistency existing between additive and resin can additive exist steadily and evenly in film for a long term. “Transport phenomenon” easily occurs where the consistency is bad. If occurs in liquid additives, we call that “sweat”; if occurs in solid additives, we call that “blooming”. But sometimes less good consistency are also allowed if the requirement of thin film is not too strict. For example, the consistency between filler and resin is bad, but as long as filled granularity is small, the film performance requirement can be basically reached. Certainly, if deal with coupling reagent, it will give full to its function. But some additives to improve film surface properties, such as plastic lubricant and antistatic agent, are required to possess some mobility to make them play a role at the surface of film.

Durability requires additives to exist in film for a long time, with little or no loss. While there are three ways: volatilization, extraction and removal for additive losses. They are mainly related to the molecular size of additive and the solubility in medium and resin. Some resin processing conditions are severe, for example processing high-temperature, then it should be considered that whether selected additives decompose or corrode processing equipments.

Film Usage Restricting to Additives

Film with different usages has requirements for the smell, virulence, weather fastness, thermal properties of additives. For example, food plastic bags must be non-poisonous, so their additives are different from those used in normal plastic bags.

Synergy and antagonism of additives’ combination exist in the same resin system. Some two additives produce synergistic effect, which means that compared with using one additive alone, it brings much more functions into play. But if additives are mismatched, some of them may produce antagonism. And this weakens the functions of each additive and even makes them lose functions completely. We should pay much attention to it. For example, if we use carbon black and amine or phenols antioxygen simultaneously, antagonism is to be produced.

Additive for the Common Used Properties of Plastic Packaging Film

Plasticizer and heat stabilizer, plasticizer, just as its name implies, is to increase plasticity. That is adding into resin, on one hand, to increase fluidity at the time of resin formation and improve processability, on the other hand, to increase the suppleness and elasticity of the made film.

Heat stabilizer is the additive to improve the heat stability of resin. It is mainly used in processing PVC and vinyl chloride copolymer. High polymer materials are easily aging under sun exposure, light exposure and high energy ray exposure and show yellowing, embrittlement, chap, surface staining, greatly reduced mechanical property and electrical property, even losing use value. In this complicated destruction process, ultraviolet light is the main reason for the aging. This is the consequence of ultraviolet light in the sunshine in combination with oxy polymer macromolecule in atmosphere.