Uv-led radically curable offset printing inks and printing processes

A UV-LED radically curable offset printing ink having a viscosity in the range of about 2.5 to about 25 Pa s at 40° C. and 1000 s−1 for offset printing a feature on a substrate, said UV-LED radically curable offset printing ink comprising:

• i) from about 10 wt. % to about 80 wt. % of one or more radically curable (meth)acrylate compounds consisting of one or more radically curable (meth)acrylate oligomers and one or more radically curable (meth)acrylate monomers, said radically curable (meth)acrylate oligomers being selected from the group consisting of epoxy (meth)acrylates, (meth)acrylated oils, (meth)acrylated epoxidized oils, polyester (meth)acrylates, aliphatic or aromatic polyurethane (meth)acrylates, polyacrylic acid (meth)acrylates, polyacrylate esters (meth)acrylates and mixtures thereof, and
• said radically curable (meth)acrylate monomers being selected from the group consisting of mono(meth) acrylates, di(meth)acrylates, tri(meth)acrylates, tetra(meth)acrylates, penta(meth)acrylates, hexa(meth)acrylates and mixtures thereof;
• ii) from about 4 wt. % to about 20 wt. % of one or more photoinitiators of formula (I):
• wherein Q has the following formula (IIa), (IIb) or (IIc):
• wherein n is equal to or bigger than 1, R1 are identical or different from each other and are selected from the group consisting of hydrogen and C1-C3-alkyl groups, R2 are selected from the group consisting of hydrogen and C1-C3-alkyl groups, and wherein the sum a+b+c is between 3 and 12 and the sum d+e+f+g is between 4 and 16,
• iii) from about 1 wt. % to about 15 wt. % of one or more amino containing compounds selected from the group consisting of aminobenzoate compounds having a weight average molecular weight of at least 400 g/mol eq PS, amine modified polyether based acrylates having a weight average molecular weight of at least 400 g/mol eq PS and combinations thereof, and
• iv) from about 1 wt. % to about 30 wt. % of one or more inorganic pigments and/or one or more organic pigments, and
• v) from about 0.5 wt. % to about 10 wt. % of one or more fillers and/or extenders, selected from the group consisting of carbon fibers, talcs, micas, wollastonites, clays kaolins, carbonates, silicates, sulfates, titanates, alumina hydrates, silica, montmorillonites, graphites, bentonites, vermiculites, wood flours, quartz flours, natural fibers, synthetic fibers and combinations thereof,
• the weight percents being based on the total weight of the UV-LED radically curable offset printing ink.