The future development of screen printing ink is promising (3)

Third, ultraviolet light solid ink and light solid drying technology is the development trend of screen printing

Screen-printing UV inks are radical photopolymers that undergo very rapid changes due to UV radiation and cause polymerization. This characteristic requires the ink to have a special structure that is compatible with this reaction.

The composition of UV ink and ordinary ink is as follows:
Composition of UV Ink Common Ink Composition Pigment Pigment Prepolymer or Polymer Resin Resin Monomer Driers Additive Additives

Ultraviolet light-cured inks, although their composition, appearance, and rheological properties are similar to ordinary inks, their components must contain materials that are compatible with UV light curing drying conditions. Unlike pigments, its chemical composition and surface treatment affect the ability of UV radiation and the ink to cure and dry. The ultraviolet transmission spectra of the four pigments used in the European color standard range from 200 to 400 mm. According to the curve analysis of the spectrum, it can be determined that each pigment maintains its fixed spectral range. But only the carbon black pigment is the exception, it absorbs almost all of the UV spectrum. Spectral measurements were performed on dispersion sheets of aqueous pigments with a depth of 10 mm.

As previously described, UV inks consist of binders: prepolymers and monomers, as well as photosensitizers and pigments of a certain composition. A photosensitizer is a compound that can be formed under the influence of ultraviolet rays to form radicals. This compound can initiate polymerization of the initial monomer and the prepolymerized reactive group, and at the same time, the ink is cured and dried. The speed of curing and drying depends on the correct choice of pigments and the choice of photosensitizers that enable the inks to produce the desired photocuring under UV conditions. Unlike solvent-based inks, the use of UV-curing dried inks does not lose the fine-grainedness of printed images due to drying. Because the ink is not irradiated with ultraviolet rays, it is uniformly stable and has no drying characteristics. When the printed product passes through the ultraviolet irradiating device for about 1 to 2 seconds, the ink is cured and dried, and the printed product can be directly stacked together. When the UV ink is cured, there is actually no loss of ink, and the resulting ink film is much thicker than the solvent ink. When the solvent ink is dried, it is volatilized through the solvent and the ink film thickness is lost by about 60%. At present, the UV ink curing and drying device stack is too thick for the ink layer to transmit, and the ink layer can only be surface-cured, so the impression ink has adhesion and durability to the substrate.

Source: China Ink Technology Network