Equipment and method for continuously preparing high-purity AKD (Alkyl Ketene Dimer) without solvent

Abstract

The invention provides equipment and method for continuously preparing high-purity AKD (Alkyl Ketene Dimer) without a solvent. The used equipment comprises a reactor for enabling raw materials to be continuously mixed and reacted. The main preparation process comprises the following steps of: at first, continuously adding tertiary amine at a reactor starting end, and continuously adding acyl chloride by dividing into three to ten paths; secondly, in a working state of the reactor, driving an inner cylinder to rotate relative to an outer cylinder by using a main motor, so that the added materials are forced to be transported and stirred by blades on transportation sections of an annular cylindrical channel, and are sufficiently cut and mixed on mixing sections through relative motion of a cutting sheet and a kneading sheet; and alternatively distributing the transportation sections and the mixing sections one by one in the axial direction of the annular cylindrical channel, so that the added materials sufficiently react, and a temperature of the materials can be controlled through an inner-outer heat exchange system until products are continuously discharged from a discharging opening. With the adoption of the equipment and the process of the invention, the reaction heat can be generated in a diffused manner, the materials can be sufficiently mixed, the entire reaction can be realized, a reaction temperature and a material viscosity are easy to control, the generation of side reaction can be reduced, and the high purity of the product can be ensured.

Description

technical field [0001] The present invention relates to a method for continuously preparing AKD (alkyl or alkenyl ketene dimer), in particular to a method for preparing high-purity AKD through continuous metering of raw materials and fully mixing and continuous reaction in the absence of solvent Methods. Background technique [0002] AKD (Alkyl or alkenyl ketene dimer) is a sizing agent used in papermaking. At present, the AKD products produced on an industrial scale are obtained by batch production. With the growth of market demand, this production method shows great limitations and many defects, such as large fluctuations in quality, high labor costs, large consumption of raw materials and energy, etc. In recent years, the continuous preparation of AKD has become the development direction of large-scale production. Both the European patent EP0550107 and the Chinese patent CN1596252A disclose methods for the continuous preparation of AKD. However, in the above-mentioned ...

AI Technical Summary

Problems solved by technology

In two embodiments, the tertiary amine of one of the materials is added at one time, and another kind of material acid chloride is then added in two times. The product purity has been greatly improved compared with the comparative example. Although the iodine value of the resulting product can be stabilized at 43, However, the iodine value is about 2 lower than that of batch-produced products, and the melting point is about 0.5~1°C lower, which shows that there are more impurities, the product purity is not high enough, and the product quality is not good; if the material acid chloride is added in three times , due to the limitation of the length of the reactor, the reaction time is short, especially after the last batch of materials is added, the stirring is insufficient, and the purity of the obtained product is not significantly improved

The above reasons affecting the quality of the obtained product are: (1) under the condition of no solvent, the reaction proceeds very rapidly. Even if the acid chloride, one of the materials, is added at two points, the heat of reaction is still concentrated, and the reaction temperature is difficult to control. The viscosity of the material is still high; (2) The reactor relies on intermittent screw blades for shearing and kneading, the structure is relatively simple, the axial and radial mixing strengths are small, and the self-cleaning ability is poor, so that the material in the reactor may Shaft holding and wall formation occur, and due to difficulty in heat dissipation, the reaction temperature rises and the viscosity of the material increases, making the materials unable to be fully mixed, resulting in incomplete dimerization of acid chlorides and tertiary amines, and continuous preparation of high-purity AKD products.

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