International. Polymers have low-energy surfaces and are difficult to adhere to water-based inks due to their higher surface tension. A study by Chinese researchers describes an approach to preparing acrylic resin used as a binder for water-based printing inks in plastic films with excellent adhesion and water resistance.
Epoxy resin is incorporated into acrylic resin to improve molecular interactions between ink binder molecules and plastic film surface molecules.
The binding resin is obtained by esterifying epoxy resin with methyl acrylic acid and then copolymerizing the product with various acrylic monomers. Acrylic resin modified by bisphenol A epoxy resins (EP-MA-AR) shows a significant improvement over unmodified acrylic resin (AR) in the adhesion between the ink and the PET film surface, as well as in water resistance performance.
N-hydroxymethyl acrylamide (NHMA) is introduced in the recipe to further improve the interactions between polymer chains in ink and polar groups on the surface of non-polar PP film caused by corona discharge treatment and dramatically improves the adhesion between ink and PP film surface, whatever the use of AR or EP-MA-AR as a binder.
The adhesion between the ink and the surface of the PET film is also further improved with this method. The water resistance of AR and EP-MA-AR is also greatly improved with the appropriate NHMA content. Two Tg appear on the DSC curve of EP-MA-AR, suggesting the separate state of epoxy-modified acrylic chains and unmodified acrylic chains in EP-MA-AR. Experimental data from water-based ink in PET and PP indicate that EP-MA-AR resin prepared in this way is an applicable water-based ink binder on plastic film.
Source: www.sciencedirect.com
