The bottomed varnish or the full-text version of the ink, in the substrate carrier, the penetration of the pigment into the ink film and the oil film causes the surface ink or varnish color pigment to change or develop. We know that pigments that bleed easily precipitate on the surface of the printing ink ink film or coating oil film.
The coloring material in the surface of a package such as a plastic or aluminum foil substrate or the color pigment in the underprint layer is dissolved by the solvent of the surface ink and migrates into the ink film or oil film to cause bleed and bloom. Generally, inorganic pigments do not have such problems. Red or purple organic pigments are more problematic. The base ink or base oil is compatible with the solvent in the surface ink system, and the solvent resistance of the pigment should be taken into consideration.
For the diversity of packaging plastics or foil substrates, the following methods can be used: (1) In order to prevent bleeding, sealable base oil or full-size white or yellow ink can be used, and their solubility and leveling properties are good. . For another example, the alcohol-soluble polyamide resin is combined with polyvinyl butyral or Damar resin with silver powder, mica powder, etc. to make up a single-component white ink or varnish with a closed color and a two-component polyurethane ink. (2) In the use of organic pigments, pigments with good solvent resistance, base oil, surface oil, ink color, and hue with structural colors that are as close as possible should be selected; <3) when the ink, varnish, or printing When the primer is a one-component thermoplastic ink or varnish, a small amount of a thermosetting resin binder is added in an appropriate amount to ensure the ink film adhesion after cooking. The solvent on the surface of the ink film should be compatible with poor solvent; (4) When the full version of white ink or yellow ink or full-bottom oil is completely cured, the surface color printing is performed again, and the overprint color is dry when printing. Afterwards, perform the final underprint or full version of the varnish.
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