In the manufacture of paints and coatings, a balance must be struck between the desire for lower volatile organic compounds (VOC) content and adequate film properties. To this end, raw material suppliers continue to develop new products that allow OPV formulations to maintain their desired performance without increasing VOC content. Amongst these are non-phthalate, low VOC coalescents and plasticizers that are compatible with a variety of polymers.
Coalescents and plasticizers are important additives in the production of biopolymer-based films and coatings. They improve flexibility, handling and appearance of films as well as enhance their mud crack resistance, open time/wet edge, chemical and scrub/rub resistance and dry/scratch resistance. Moreover, they can increase water content and vapor permeability of the final film.
Typically, plasticizers are low volatile substances that are introduced into a polymer system to make it more workable. They may be either external or internal. External plasticizers are added to the system as a separate substance, and they are not attached to polymer chains by primary bonds. The plasticizer molecules provide space between polymer chains, thereby lowering Tg and reducing elastic modulus.
Generally, the higher the molecular weight and number of hydroxyl groups present on a plasticizer, the more effective it will be as a plasticizer for protein-based materials. For example, GLY has been found to be a good plasticizer for fish proteins, reducing opacity and color as well as Tg. Further, film plasticized with GLY and varying concentrations of PEG exhibited a synergistic effect with respect to mechanical properties (tensile strength, elongation at break) and water vapor permeability.