Printing ink which can be hardened with low pressure mercury lamp for e.g. screen printing - has matrix based on polymerisable silicic acid polycondensates, pigments, photoinitiators, and opt. conventional additives.

: Kappel, J.; Kron, J.; Martin, A.; Wolter, H.; Popall, M.

Abstract
Printing ink which can be hardened with a low-pressure Hg lamp, contg. a matrix based on polymerisable silicic acid (hetero)polycondensate(s) in amts. of 20-95 wt%, one or more organic and/or inorganic pigments, photoinitiator(s) and opt. conventional additives. The polycondensates are obtd. by the hydrolytic condensation of hydrolysable cpds. of Si and opt. other elements selected from B, Al, P, Sn, Pb, transition metals, lanthanides and actinides, and/or of precondensates derived from it, by the action of water or moisture, opt. in presence of catalyst and/or solvent. 20-100 mole% of these hydrolysable cpds. (w.r.t. monomeric cpds.) consists of silanes of formula (I) XaRbSiYc (I) R = alkyl, alkenyl, aryl, alkaryl or aralkyl; X = H, halogen, OH, alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl or NR'2 (with R' = H, alkyl or aryl); Y = 2-50C organic residue contg. C=C double bond(s) and/or epoxide gp(s). and opt. in-chain O and/or S and/or amino; a, c = 1, 2 or 3; b = 0, 1 or 2; and a + b + c = 4. USE - Used in flexographic, offset or screen printing, for printing on paper, glass, ceramics, metallic surfaces or plastics (claimed). ADVANTAGE - Provides printing ink which can be hardened rapidly with a low-pressure Hg lamp and can therefore be used in high-speed web printing processes, without expensive cooling equipment or excimer lasers. The ink also has all the other properties required for the intended applications (w.r.t. viscosity, printability at high speed, compatibility with water and solvents, wetting properties, adhesion to paper and other substrates, pigment binding etc.)