Polyester Resins for Coating Cans with Improved Resistance to Stamping Operations: A View on Specific Properties

Abstract

Compositions containing epoxy diane oligomers make up a major of coatings applied to the insides of cans and other metal containers. Even though such materials allow producing coatings with good adhesion to metal substrates, with proper chemical resistance and elasticity, they have one major drawback, caused by the key component of diane epoxy resins, by the bisphenol A. The danger of this substance is that it has a negative effect on the human brain and the reproductive system, and sparks cancer. Therefore, such materials are I limited use. Composites based on polyester resins are a good alternative with good prospects. However, polyester coatings intended for cans and other packages have low resistance to sterilization, which is typically prior to a food canning process. The reason why this parameter is low is that given polymers contain a relatively high content of ester groups, which are characterized by low resistance to water, alkaline and acid agents. Such coatings can be improved in resistance by enriching the composition of their polymer macromolecules with unsaturated monomers that can homopolymerize when polyester compositions cure. These fragments are to create additional steric hindrance on diffusion for destructive ester groups and to ensure the endurance of coatings in general.