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The performance of pvc film changes due to the different plasticizers used, and the relationship between film performance and the chemical structure of the plasticizer. When the film is required to have certain special properties, it is very complicated to determine the film formulation, and certain requirements for the film are sometimes contradictory. It is very difficult to produce a film with good cold resistance and flame retardancy. If oil resistance is also required at the same time, the use of currently known plasticizers still cannot meet the requirements. Therefore, an appropriate plasticizer ratio must be selected when manufacturing the film, and the shortcomings of various plasticizers must be compensated by means of complementing each other to meet the requirements of use.
Generally, the plasticizer content of PVC soft film is 18-45%. When the plasticizer is used as a processing aid, when the added amount is less than 18%, a peculiar phenomenon can be seen, that is, the film with this content is not softer than pure PVC hard film but more brittle. Its impact strength and cold resistance are worse than pure PVC hard film. This phenomenon may be due to the small amount of plasticizer, and it is impossible to "eliminate" the polarity of the polyvinyl chloride molecule.
Films with a plasticizer content of less than 18-20% are mostly not made of pure polyvinyl chloride, but are often not brittle and impact-resistant polyvinyl chloride.
Films containing more than 45% of plasticizers are difficult to manufacture, because of their low strength, high elongation, and stickiness, so they are rarely produced.
The higher the plasticizer content of the film, the more obvious the impact on the performance of the film. In order to achieve the same softness, if the plasticizer used is different, the added amount is also different. In the comparative test of different films, the film with the same hardness is often used as the benchmark, rather than the film with the same plasticizer content as the benchmark.
