| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a water soluble ink composition excellent in rub resistance against printed materials, and also excellent in storage stability and discharge stability (redispersibility). <P>SOLUTION: An ink composition includes: a dispersion resin; a pigment; a basic compound; water; and a water-soluble organic medium. The dispersion resin is a copolymer having a weight average molecular weight of 12,000-35,000 and an acid number of 100-250 mg KOH/g, and obtained by copolymerization of 30-83 wt.% of (α-methyl) styrene and/or an aromatic group-containing (meth)acrylic acid ester, as a first monomer, 40-12 wt.% of (meth)acrylic acid, as a second monomer, and 30-5 wt.% of an alkylene oxide group-containing (meth)acryl acid ester represented as the following general formula 1, as a third monomer. General formula 1: CH<SB POS="POST">2</SB>=C(R<SP POS="POST">1</SP>)COO(CH<SB POS="POST">2</SB>CH<SB POS="POST">2</SB>O)<SB POS="POST">n</SB>-R<SP POS="POST">2</SP>[In the formula, R<SP POS="POST">1</SP>and R<SP POS="POST">2</SP>each represents H or CH<SB POS="POST">3</SB>, and n represents an integer of 2-24]. <P>COPYRIGHT: (C)2013,JPO&INPIT |
