| 摘要 |
PURPOSE:To obtain a colorant requiring only addition to water at the time of use, unnecessitating mixing with cement and stirring and considerably increasing work efficiency as compared with an inorg. colorant by forming a polycondensation product of ligninsulfonic acid having a brown color tone. CONSTITUTION:A polycondensation product of ligninsulfonic acid having a brown color tone is used as a colorant for cement. This colorant is obtd. by adding a soln. of an alkali such as NaOH to waste liquor from a sulfite pulp mill, bringing them into a reaction at a high temp., preferably 120-260 deg.C and drying a dark-colored precipitate formed by the polycondensation of ligninsulfonic acid. |
