| 摘要 |
PURPOSE: Provided are pigment dispersions, more specifically which are low in viscosity and excellent in flowability and are useful for writing instruments, printers and the like. and also writing instruments and printers with the dispersions stored therein are provided. CONSTITUTION: A polymeric dispersant (hereinafter simply called "polymer") for use in the present invention has, on side chains thereof, carboxyl groups derived from a dibasic acid. More desirably, the carboxyl groups are those derived from a dibasic acid of a cyclic compound. Such a polymer can be obtained by one of processes to be described hereinafter. A first process is to mix a monomer containing both an addition-polymerizable group and a carboxyl group, desirably a monomer which contains a residual group of a saturated or unsaturated, carboxyl-containing cyclic compound, said residual group being bonded directly or via a connecting group (see formula 1 below) to a moiety containing an addition-polymerizable group, with another monomer polymerizable with the first-mentioned monomer and then to copolymerize the resulting mixture. A second process is to react an acid anhydride of a dibasic acid, for example, phthalic anhydride or the like with a polymer containing groups reactive with an acid anhydride, such as hydroxyl groups (see formula 2 below). The process of the formula 1 is more preferred.
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