| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain an offset printing ink which can permit to print the both face and back of paper without cessation because the face need not be dried after it is printed, is reduced in blanket separation and picking, and is improved in ink transfer to an impression cylinder by including a rosin-modified phenolic resin obtained by reacting a rosin with a specified phenolic resin. SOLUTION: A phenolic resin made from a 4-10C alkyl-containing phenol is reacted with a rosin to obtain a rosin-modified phenolic resin having a weight- average molecular weight (in terms of the polystyrene) of 30,000-100,000. 15-30 wt.% obtained resin is milled with 1-20 wt.% aliphatic hydrocarbon solvent having a boiling point of 250-360 deg.C, a synthetic resin such as another known rosin-modified phenolic resin or an alkyd resin, a drying oil, a pigment such as an organic pigment or an inorganic pigment, a solvent such as a varnish or light oil, a drying accelerator such as a metallic soap, etc.</p> |
