Method for producing naphthalene water reducing agent

Abstract

The invention discloses a method for producing naphthalene water reducing agent, which comprises the following steps: (1) sulphonating: adding naphthalene, concentrated sulfuric acid and anhydrous sodium sulfate while stirring into a reactor, and making the materials react at 160-165 DEG C for 2-3 hours, wherein the molar ratio of the naphthalene to the concentrated sulfuric acid is 1:1.3 to 1.5, and the addition amount of the anhydrous sodium sulfate is 5-9% by the weight percent of the concentrated sulfuric acid; (2) hydrolyzing: adding water to the reaction solution to control the acidity at 27-29%, and stirring for 30 minutes; (3) condensing: adding formaldehyde to the reaction solution, and making the formaldehyde react with the reaction solution at 100-110 DEG C for 3-4 hours, wherein the molar ratio of the formaldehyde to naphthalene sulfonate is 0.7 to 1.5:1; (4) neutralizing: adding alkali to the reaction solution to neutralize the reaction solution, and controlling the pH value at 7-9; and (5) filtering: filtering to remove unnecessary sulfate to obtain the naphthalene water reducing agent. The method for producing the naphthalene water reducing agent by adopting one pot has the advantages of cheap and readily available raw materials, safe and mile reaction condition, simple process, safe operation, high reaction yield and low cost and can be used for industrial production on a large scale.

Description

technical field [0001] The invention relates to a building material, in particular to a method for producing a naphthalene-based water reducing agent for building. Background technique [0002] Naphthalene series superplasticizer is the largest polycondensation type superplasticizer in my country, and it is also one of the earliest popular cement admixtures in China. With the development and development of the market, the competition is becoming increasingly fierce. [0003] The existing classical production process is: 1) sulfonation reaction of industrial naphthalene and concentrated sulfuric acid; 2) hydrolysis; 3) condensation; 4) neutralization; 5) filtration. Wherein, in the sulfonation reaction of the first step, naphthalene and concentrated sulfuric acid generate 2-naphthalenesulfonic acid and water, and the generated water will dilute the concentrated sulfuric acid, thereby affecting the continuation of the reaction, reducing the sulfonation reaction rate and the s...

AI Technical Summary

Problems solved by technology

Among them, in the sulfonation reaction of the first step, naphthalene and concentrated sulfuric acid generate 2-naphthalenesulfonic acid and water, and the generated water will dilute the concentrated sulfuric acid, thereby affecting the continuation of the reaction, reducing the sulfonation reaction rate and sulfonation conversion efficiency , in the prior art, either adopt benzene to carry water to remove the water generated by the reaction, so that the reaction proceeds smoothly; or, feed sulfur trioxide into the reactor so that the concentration of the concentrated sulfuric acid does not decrease; however, the benzene The toxicity is relatively high, which is unfavorable to the environment, and the post-treatment is cumbersome and costly; while the introduction of sulfur trioxide makes the reaction not mild enough, and the operation risk is relatively high