Sep. 09, 2019
Fluorescent Brightener China can improve the whiteness and luster of the material, making the product bright and eye-catching, and is widely used in industrial products such as detergent, textile, paper, plastic, paint and so on. Among them, triazine stilbene-type fluorescent whitening agent has been the most popular type of fluorescent whitening agent in China, which has the earliest introduction technology, the largest yield and the widest application range.
Fluorescent Whitening Agent Supplier reviews the whitening principle, application, types and structural characteristics of fluorescent whitening agents. Several common bistriazinyl stilbene-based fluorescent whitening agents are also reviewed, and the parent 4,4'-diaminostilbene-2,2'-disulfonic acid (DSD acid) is also simple. Introduction.
First, the synthesis of DSD acid includes two parts of oxidation reaction and reduction reaction. For the oxidized part, we chose p-nitrotoluene o-sulfonic acid to be oxidized by sodium hypochlorite under alkaline conditions to obtain 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS acid). The rate was 89.1% (literature value 85%). For the reduced part, the DNS acid was subjected to reduction reaction under mildly acidic conditions to obtain the product DSD acid. The related process was investigated, and the final yield reached 96.5% (literature value 90-95%).
In this paper, three kinds of fluorescent whitening agents, namely FWA220, FWA113 and FWA357, were synthesized. They are all bistriazinylaminostilbene fluorescent whitening agents. These fluorescent whitening agents are based on DSD acid and cyanuric chloride. The remaining chlorine atoms on cyanuric chloride are successively used by certain compounds. It replaces the fluorescent whitening agents that make up many varieties. Due to their similar structure, the synthesis conditions are basically the same. Taking FWA220 as an example, the optimum process conditions were obtained by discussing the conditions of pH, temperature, feed ratio, dispersant selection and purification:
The first step of condensation conditions: T = 0 ~ 5 ° C, pH = 3 ~ 4, m (p-aminobenzenesulfonic acid): m (cyanuric chloride) = 0.94: 1, the amount of water used for dispersion is cyanuric chloride 20 Times.
The second step of condensation conditions: T = 55 ~ 60 ° C, pH = 6 ~ 7, m (DSD acid): m (cyanuric chloride) = 0.47: 1;
The third step of condensation: T = 90 ~ 95 ° C, pH = 9 ~ 10, the amount of diethanolamine is equivalent to 1.4 times calculated by the amount of cyanuric chloride.
Fluorescent whitening agent HPLC analysis method: mobile phase A: acetonitrile, mobile phase B: 0.4% (w/v) tetrabutylammonium hydrogen sulfate, pH = 8.0, flow ratio: A: B = 50:50. The column was selected from a HanbonHedera ODS-3C18 column with a column size of 4.6 mm x 250 mm x 5.0 μm. The column temperature was selected at 40 ° C, the flow rate was controlled: 1 mL/min, and the injection amount was 5 μL.
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