| 摘要 |
PROBLEM TO BE SOLVED: To obtain an oligomer useful for dispersing a dye or preparing a dye solution or printing paste, etc., by using a specific repeating unit and setting the weight-average molecular weight below a specific level. SOLUTION: The objective new oligomer containing the repeating unit of formula [CH3 is substituted to theαorβ-site of naphthalene nucleus and theα/βmolar ratio is 40:60 to 100:0; M is H, an alkali metal or an alkaline earth metal; (n) is 0.5-2] and having a weight-average molecular weight of <=1,500 is produced by condensing preferably anα-methylnaphthalenesulfonic acid (e.g. 1-methyl-2-naphthalenesulfonic acid) with 0.2-0.8 times mol of formaldehyde, etc., in the presence of 0.001-1 times mol of an acid (e.g. sulfuric acid) at 80-150 deg.C for 1-20 hrs.
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