ORGANIC SOLVENT-BASED CONCENTRATED INK COMPOSITION FOR GRAVURE PRINTING AND GRAVURE PRINTING METHOD

摘要

The present invention provides an organic solvent-based concentrated ink composition for gravure printing which shows good print density, printability, and laminatability even in gravure printing using a shallow cylinder. The organic solvent-based concentrated ink composition for gravure printing mainly includes a pigment; binder resin; and an organic solvent. The pigment includes at least one of an organic pigment and an inorganic pigment. The binder resin includes polyurethane resin. A solution obtainable by dissolving 30 parts by mass of the polyurethane resin in 70 parts by mass of the organic solvent has a viscosity of 100 to 500 mPa·s/25°C. The concentrated ink composition has a viscosity of 10 to 1000 mPa·s/25°C and has a viscosity in gravure printing of 12 to 23 s/25°C in terms of the efflux time from a Zahn cup #3. The concentrated ink composition satisfies one of the following conditions 1 to 3:Condition 1: the pigment being an organic pigment; the amount of the organic pigment being 5 to 20% by mass and the amount of the polyurethane resin being 3 to 20% by mass each in the organic solvent-based concentrated ink composition for gravure printing; and the amount of the polyurethane resin being 60 to 200 parts by mass for 100 parts by mass of the organic pigment;Condition 2: the pigment being an inorganic pigment; the amount of the inorganic pigment being 5 to 70% by mass and the amount of the polyurethane resin being 3 to 20% by mass each in the organic solvent-based concentrated ink composition for gravure printing; and the amount of the polyurethane resin being 5 to 60 parts by mass for 100 parts by mass of the inorganic pigment; andCondition 3: the pigment including both an organic pigment and an inorganic pigment; the amount of the organic pigment being 5 to 20% by mass in the organic solvent-based concentrated ink composition for gravure printing; the ratio by mass ((mass of inorganic pigment)/(mass of organic pigment)) of the organic pigment to the inorganic pigment satisfying 0 (mass of inorganic pigment)/(mass of organic pigment) 7.0; the amount of the polyurethane resin being 3 to 20% by mass; and the amount of the polyurethane resin being 20 to 200 parts by mass for 100 parts by mass of the whole pigments.