A kind of preparation method of mixed fluorescent whitening agent

Abstract

The invention discloses a preparation method of a mixed fluorescent whitening agent. In the current preparation process of a disulfonic fluorescent whitening agent, the problems of low feeding quantity and high unit energy consumption are caused by the fact that a product of first-step condensation reaction is high in viscosity in a water phase, and yield can be increased only through expanding a reaction kettle. The preparation method includes: adopting para-position or meta-position aminobenzene sulfonic acid and cyanuric chloride for condensation reaction to obtain a product, and adding aniline to react with remaining cyanuric chloride for condensation reaction to obtain another product; enabling a mixture of the two products to be in second-step condensation reaction with DSD acid; being in third-step condensation reaction with organic amine, adopting organic alkali to adjust pH, and finally obtaining a water solution of the mixed fluorescent whitening agent containing trisulfonic group, disulfonic group and tetrasulfonic group. When the three-component stilbene fluorescent whitening agent obtained by the method is used for whitening paper pulp, whitening effect is better than that when a single-component tetrasulfonic or disulfonic stilbene fluorescent whitening agent is used.

Description

technical field [0001] The invention relates to the field of special additives for papermaking, in particular to a preparation method of a mixed fluorescent whitening agent. Background technique [0002] Stilbene fluorescent whitening agents have the effects of whitening, brightening and brightening. In order to obtain higher whiteness, paper mills often use disulfonic acid fluorescent whitening agents in the pulp and hexasulfonic acid fluorescent whitening agents on the surface. The combination of whitening agents. [0003] In the preparation process of disulfonic acid-based fluorescent whitening agent, due to the high reactivity of aniline, such as one-step condensation with cyanuric chloride, the initial reaction is easy to condense with the first and second groups of cyanuric chloride, resulting in side effects. The product increases, so the first step of condensation often uses DSD acid and cyanuric chloride to react, and then performs the second and third steps of con...

AI Technical Summary

Problems solved by technology

[0003] In the preparation process of disulfonic acid-based fluorescent whitening agent, due to the high reactivity of aniline, such as one-step condensation with cyanuric chloride, the initial reaction is easy to condense with the first and second groups of cyanuric chloride, resulting in side effects. The product increases, so the first step of condensation often uses DSD acid and cyanuric chloride to react, and then performs the second and third steps of condensation with aniline and other organic amines. The main problem is that the first step condensation reaction product is in the water phase The viscosity is high, resulting in low feeding volume and high energy consumption per unit. The increase in production capacity can only be solved by enlarging the reactor.

Images