Manufacturing method of dibasic acid diols
I. INTRODUCTION
Dibasic acid diols are an important class of raw materials for the production of chemicals, which are widely used in plastics, coatings, adhesives, fibers and other fields. Common dibasic acid diols include ethylene glycol adipate, ethylene glycol terephthalate and so on. This article will introduce the manufacturing method of dibasic acid diol, focusing on its production process, reaction principle and operation points.
II. Production process
1. Esterification reaction
Dibasic acid and diols are esterified to produce dibasic acid esters under the action of catalysts. Commonly used catalysts include sulfuric acid, phosphoric acid and so on. The reaction process needs to control the temperature, pressure and material ratio to ensure the smooth progress of the reaction.
2. Polycondensation reaction
The dibasic acid esters undergo polycondensation reaction at high temperature and high vacuum to produce dibasic acid diol polymer. The polycondensation reaction requires control of the reaction temperature, vacuum and reaction time to obtain high molecular weight, low volatility dibasic acid diol products.
III. Reaction Principle
1. Principle of Esterification Reaction
Under the action of catalyst, dibasic acid and diol undergo esterification reaction to produce dibasic acid ester and water. The esterification reaction is reversible and requires the use of an excess of diol to ensure the reaction. At the same time, the presence of a catalyst reduces the activation energy of the reaction and increases the reaction rate.
2. Principle of Polycondensation Reaction
The dibasic acid ester undergoes polycondensation reaction at high temperature and high vacuum to produce dibasic acid diol polymer and water. The polycondensation reaction is irreversible, and the reaction is driven toward the generation of high molecular weight polymers by the continuous removal of the generated water.
IV. OPERATING POINTS
1. Temperature control
In the esterification and polycondensation reactions, the temperature needs to be strictly controlled to ensure that the reaction proceeds smoothly. Too high a temperature may lead to the occurrence of side reactions, while too low a temperature may affect the reaction rate and product quality.
2. Control vacuum
In polycondensation reactions, a high vacuum is required to remove the water generated and to facilitate the reaction. A low vacuum may result in a slower reaction rate and lower molecular weight of the product.
3. Control of material ratio
In the esterification reaction, it is necessary to control the material ratio of the dibasic acid to the diol to ensure that the reaction proceeds completely. At the same time, it is also necessary to control the material ratio in the polycondensation reaction to obtain the ideal molecular weight and product quality.
4. Selection and use of catalyst
Selection of suitable catalyst can improve the reaction rate and product quality. In the process of using, it is necessary to pay attention to the amount of catalyst and the way of adding in order to avoid adverse effects on the equipment and products.
V. Conclusion
The manufacturing method of dibasic acid diol includes two steps of esterification reaction and polycondensation reaction. In the production process, it is necessary to strictly control the operating points such as temperature, vacuum degree and material proportion to ensure product quality and production efficiency. Through the reasonable production process and operation points, high-quality dibasic acid diol products can be manufactured, providing important production raw materials for plastics, coatings, adhesives, fibers and other fields.
