To provide printing ink resins which improve the working environment in carrying out reaction by not using formaldehyde and the like in the synthesis of the resins to reduce the total resin production cost due to no need of treating equipment and excel in the solubility in a printing ink solvent, misting and drying characteristics.
A method of preparing a printing ink resin comprises reacting a Diels-Adler reaction product of (A) a resin acid and (B) an α,β-ethylenically unsaturated carboxylic acid or its anhydride with (C) a dihydric 6-60C alcohol or a dihydric 6-60C alcohol and (D) a tri- or higher hydric polyol, and the weight ratio of the resin acid (A) to the α,β-ethylenically unsaturated carboxylic acid or its anhydride (B) is 80/20 to 97/3, and the ratio of the total molar number of carboxylic acids of resin acid (A) and α,β-ethylenically unsaturated carboxylic acid or its anhydride (B) to the total molar number of hydroxyl groups of dihydric 6-60C alcohol (C) and tri- or higher hydric polyol (D) is 1/0.5 to 1/1.2.
YASUIKE MADOKA
UTSUGI MASAKI
YAJIMA HISAO
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