Low-migration and low-swelling sheet offset printing ink

An offset printing ink is provided which comprises a colophony-modified phenolic resin and at least one component selected from the group consisting of a maleic resin,a modified hydrocarbon resin,a colophony resin ester and mixtures thereof. The printing inks further comprise a water-insoluble fatty acid ester of a multivalent alcohol which has a high steric spatial requirement, and/or ethinol.

On the one hand, sheetfed printing inks are known in the prior art which can be described as low as to odor and flavor. These offset printing inks contain low odor components such as hard resins, hydrogenated mineral oil cuts, synthetic aromatic oils, alkyd resins, in particular such with a low iodine number of ≤30 g J2/100 g, and dialkyl ether such as di-n-dodecyl ether, di-n-undecyl ether, allyl-n-octyl ether, n-hexyl-n-undecyl ether as a vehicle.

However, mass transfers of theseoffset ink to the filling material can occur, the mass transfers being assessable according to the law of diffusion. However, the German food law prohibits any mass transfer, except for components which are safe with regard to health, odor and flavor and which are technically unavoidable. Migration of the liquid components in inks of the prior art can occur, however, which can further cause the unwanted aspect of the so-called swelling. As a result of migration, in particular thin packing films, i.e. films under 30 μm, can be affected by warping of the film in form of wrinkling and waves. These warps are irreversible and optically and technically non-acceptable.

 

Furthermore, so-called anti-swelling inks are known in the prior art which have a vehicle composition free of mineral oil. The serious disadvantage of these inks is, however, that the low-viscous vehicle components can have considerable migration potentials. Therefore, it is possible that mass transfers occur in primary packing which can disadvantageously change the odor and flavor of the filling material, in particular of the food. 

Therefore, it was an object of the invention to provide sheet-fed offset printing inks which are low in migration and odor as well as low in swelling, and which, therefore, do not cause any unwanted changes in odor and flavor of the wrapping and which obey the migration values stipulated by law, respectively.