After the tinplate printing is completed, a layer of varnish needs to be applied to increase the gloss and scratch resistance of the printed tinplate sheet surface, and also increase a certain hardness, so that the process color printing surface coating film has certain flexibility and corrosion resistance. The tinplate printing varnish should have the following functions:
(1) Tinplate printing varnish has high hardness and strong adhesion, and the printed tinplate sheet can withstand the processing deformation of the subsequent process.
(2) The color of printed tinplate sheet retention performance is good, and the solvent in the tinplate printing varnish cannot cause the ink to bleed or fade.
(3) Tinplate printing varnish matching with white paint or primer, can not corrode white paint or primer.
