SYNTHETIC RESIN FOR PRINTING INK, PRODUCTION THEREOF, AND PRINTING INK

PROBLEM TO BE SOLVED: To obtain a synthetic resin that is useful for a binder of ink, which gives printed matters excellent in gloss and dryability while hardly leaving behind an org. solvent by selecting a synthetic resin having a specified number average mol.wt. and a specific structure contg. rosin residues. SOLUTION: The synthetic resin having a number average mol.wt. of 400-5,000 and a structure of formula I is selected. In the formula I, M1 is a di- to tetravalent metal, pref. Al, Zr, or Ti; X is a group of formula II; R2 is a rosin residue having an α,β-monoethylenically unsatd. carboxylic acid added thereto; M2 is a divalent metal; R1 is a rosin residue or R2 ; m is 1-30; and n is 2-4. This resin can be produced by reacting an α,β-monoethylenically unsatd. carboxylic acid (e.g. fumaric acid) with rosin (e.g. tall oil rosin), reacting the resultant carboxylated rosin with a divalent metal compd. [e.g. Ca(OH)2 ], and reacting the resultant product with a di-, tri-, or tetravalent metal compd. (e.g. aluminum triisopropylate).