| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a composition which solve problems in terms of stability on a machine, surroundings for printing work, setting time and the like wherein a weight- average molecular weight of a resin for a printing ink is not less than a specified value and a number-average molecular weight of the resin is not less than a specified value. SOLUTION: A resin composition is composed of: 20-80 pts.wt. of the resin of a printing ink having a weight-average molecular weight of not less than 15,000 and a number-average molecular weight of not less than 5,000; 10-30 pts.wt. of a vegetable oil; and 10-50 pts.wt. of a petroleum solvent having the high boiling point, and obtained by heat dissolving and mixing them at 150-280 deg.C for 5-240 min. The resin for the printing ink uses: a rosin-modified phenol resin wherein a resin precursor is a resol resin having not less than 4 of nuclear form number; a petroleum-modified phenol resin; a maleic acid-modified phenol resin; an alkyd resin, and the like. The resin of which the molecular weight distribution can be controlled is obtained by dissolving a commercially available resin for a printing ink in a good solvent such as toluene and xylene followed by adding a poor solvent such as methanol and ethanol to perform reprecipitation treatment, filtration and drying.</p> |
