Method for manufacturing printed matter

Abstract

This method for manufacturing printed matter has, in the following order, a step 1 for providing a UV-curable offset ink layer on a base material, and a step 2 for curing the UV-curable offset ink layer using UV rays in an atmosphere having an oxygen concentration of no more than 5%, wherein the method is characterized in that the UV-curable offset ink contains a non-reactive resin having a glass transition temperature of 30-140 DEG C, a (meth)acryl monomer and / or a (meth)acryl oligomer, a photoinitiator, and a pigment.

Description

technical field [0001] The present invention relates to a method for producing printed matter with ultraviolet-curable lithographic ink on a paper or plastic substrate. Background technique [0002] Printing inks that harden under ultraviolet irradiation or electron beam irradiation are widely used mainly for package printing for food packaging such as paper utensils due to the convenience of their instant drying characteristics. In recent years, in food packaging, there has been concern about the transfer (migration) of chemical substances in ink to the food package. For example, migration caused by electron beams (hereinafter sometimes referred to as EB (Electronic Beam) In the case of curable ink, the unreacted monomer in the ink component moves away from the printing surface and dissolves into the food contained in it; The printed surface is separated and eluted to the food inside. In addition, regarding the photopolymerization initiator, there are also cases where the ...

AI Technical Summary

Problems solved by technology

Ink usually contains a pigment as a colorant for its purpose, but pigments that absorb visible light and emit a specific color are known to absorb in the ultraviolet region, and thus prevent ultraviolet curing (see, for example, Non-Patent Document 1)

In particular, carbon black used in black inks absorbs ultraviolet rays in the full ultraviolet wavelength range, which may cause poor hardening of the surface of the printed matter, and ultraviolet rays cannot reach the inside of the coating film, resulting in insufficient hardening of the inside of the coating film.

In addition, as a result of the difference in curability between the surface and interior of the coating film, the volume of the cured film of the ink shrinks, or the flexibility of the film is impaired, so the adhesion to the substrate may also be significantly reduced.

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