A kind of nylon salt and preparation method thereof

Abstract

The present invention provides a method for preparing nylon salt, which comprises mixing 1,5-pentanediamine, water and dicarboxylic acid at a temperature of 65 to 120°C to obtain a nylon salt, wherein the amount of the water is 2% to 12% by weight based on the total weight of the 1,5-pentanediamine and the dicarboxylic acid. The present invention also provides a nylon salt. According to the present method for preparing nylon salt, the incomplete reaction between the 1,5-pentanediamine and the dicarboxylic acid, which is caused by the nylon salt present during the preparation in a solid state, can be avoided; the reaction between the 1,5-pentanediamine and the dicarboxylic acid can be significantly speeded up, and the reaction time is accordingly shorten. Consequently, the content of diamine and dicarboxylic acid remained in the resulting nylon salt is very low. In addition, the final nylon salt product, which present in a solid state, makes it easier to be stored and transported.

Description

technical field [0001] The invention relates to a nylon salt and a preparation method thereof, in particular to a preparation method of a nylon salt with less residual diamine and diacid. Background technique [0002] In the prior art, nylon is mainly synthesized by the polycondensation reaction of dibasic acid and diamine. In order to ensure the equimolar ratio of dibasic acid and diamine raw materials as much as possible, the dibasic acid and diamine are usually made into nylon salt first. , and then undergo polycondensation. Therefore, as the precursor of nylon polymer, the product quality of nylon salt has a great influence on the quality of nylon polymer. Qualified nylon salt is the basic prerequisite for producing high-quality nylon polymer. [0003] Nylon salts currently on the market include nylon salt solutions and nylon salt solids. Due to the high water content, long-distance transportation is economically uneconomical, and the nylon salt solution has poor stab...

AI Technical Summary

Problems solved by technology

[0007] However, the above-mentioned existing solution-based nylon salt preparation technology has the following problems: when water is used as a solvent to prepare a nylon salt solution, because the solubility of nylon salt in an aqueous solution is relatively large, it is difficult to effectively obtain a nylon salt solid by cooling and crystallization. , and if concentrated crystallization is used, the product quality of nylon salt will deteriorate due to high temperature

Thereby the cost of preparing nylon salt by the aqueous solution of nylon salt is high and the quality is not stable

However, when organic solvents are used to prepare solid nylon salt, it is easy to cause organic solvent residues and involve the recovery of organic solvents, high energy consumption, large pollution, high cost, and is not a very ideal process.

[0008] Patent application CN 103201314A discloses a method for preparing nylon salt by reacting liquid diamine and powdery solid diacid under the condition of low water content. However, this method needs to mix the diamine and diacid at 100-210°C above the melting point of pentamethylenediamine. The reaction is carried out in the temperature range of ℃, the reaction conditions are not mild, and the nylon salt obtained under high temperature reaction will cause yellowing of nylon in the subsequent polymerization, affecting the color of nylon

In addition, this preparation method has restrictions on the reaction system, stirring method, reaction temperature, and diacid addition method. The process is cumbersome, and is limited by its liquid-solid reaction method. There are still amine residues in the final product

[0009] In summary, the existing methods for the preparation of nylon salts are difficult to directly obtain nylon salts with low diamine and diacid residues and no influence on subsequent nylon polymerization.