| 摘要 |
PROBLEM TO BE SOLVED: To obtain a formaldehyde condensation product without impairing its dispersing performance with high productivity by specifying the amt. of water for condensation present in a reaction system at the time of the condensation reaction of a liq. sulfonation reaction product of naphthalene and formaldehyde. SOLUTION: When a liq. sulfonation reaction product of naphthalene and formaldehyde are condensed under elevated pressure of an inert gas, the amt. of water for condensation is adjusted to 7.5-8.0 times (by mol) the amt. of the naphthalene compd. and the objective slurry dispersant is produced. A formaldehyde condensation product having a number average mol.wt. of 1,200-1,500, a wt. average mol.wt. to number average mol.wt. ratio of 5.0-7.5, a high condensation degree and a sharp mol.wt. distribution can be produced in a short time. The liq. sulfonation reaction product of naphthalene preferably contains <=5 mol.% unreacted naphthalene and <=5 mol.% naphthalenedisulfonic acid as a by-product. Formaldehyde is preferably used by 0.8-1.2 mol per 1 mol naphthalene compd. |
