Today, let’s talk about the fluorescent whitening agent VBL. This whitening agent was produced by manufacturers in China in the 1960s. The product output has just begun to be used for cellulose and fabric whitening, and later it is mainly paper whitening. In the process of use, the fluorescent whitening agent VBL has several common problems: First, the fluorescent whitening agent VBL itself has few sulfonic acid groups in the molecule, and the water solubility is not ideal, which makes chemical conversion difficult. Second, the fluorescent whitening agent VBL is used in a solution with a lower pH value, which is prone to precipitation. 3. The yellowing point of the fluorescent whitening agent VBL is low, and its use in products requiring higher whitening is limited. 4. VBL; There are many non-shaped products in the product, and the appearance changes from light yellow to green, which affects the whiteness of the product. Fifth, the finished VBL contains Yuanming powder, inconsistent fineness is easy to cause dust to fly, and the material is agglomerated. Although the fluorescent whitening agent VBL has the above disadvantages, it still has an irreplaceable position due to its advantages in terms of price, performance and range of use.
There are three main raw materials for the synthesis of fluorescent brightener VBL: DSD acid, melamine, aniline and ethanolamine. The production method is a three-step condensation.
The first step of condensation: add water and ice in the condensation kettle, add leveling agent O aqueous solution, industrial hydrochloric acid, add cyanuric acid and stir for 1 hour, add DSD acid process for 3-4 hours, neutralize with sodium carbonate solution, control the pH value The amine group was measured, and when the amine group disappeared, the first step of condensation was completed.
The second step of condensation: Inject the reaction material of the first step into the second condensation kettle, add aniline, slowly raise the temperature to 15-20 degrees, and begin to neutralize with sodium carbonate. When the temperature reaches 30-40 degrees, measure the amine value. The amine value disappeared and the second step of condensation was completed.
The third step of condensation: Inject the reaction material of the second step into the third condensation kettle, add ethanolamine, raise the temperature to 75 degrees, add ammonia water, increase the temperature of the closed reaction to about 100 degrees, keep the temperature to 1-2 hours, and cool to 35-40 degrees Add water and let stand for 2 hours. After filtration, transfer to an acid precipitation kettle and heat up to 85 ° C. Add industrial hydrochloric acid acid precipitation. After the lower filter cake is dehydrated, enter the kneader, add an appropriate amount of soda ash, beat it by spray drying, and sand mill. Toner. The finished fluorescent brightener VBL was obtained.
Manufacture of liquid finished product of fluorescent whitening agent VBL. Add the sulfonic acid filter cake to the reaction kettle, add urea to start stirring, add ammonia water to neutralize, add an appropriate amount of water to ensure the strength reaches 46 parts by force, and then increase the temperature of the airtight container to 90 degrees. To room temperature, add a certain amount of CMC to make the dispersion reach a strength of 45 parts by force to obtain a finished product.
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Detailed production process of fluorescent brightener OB-1
Post time: Apr-03-2020