Method for preparing semi-aromatic polyamide

Abstract

The invention discloses a method for preparing a semi-aromatic polyamide. The method comprises the steps of adding aromatic dicarboxylic acid and aliphatic diamine containing 4 to 14 carbon atoms into a high-pressure autoclave, applying nitrogen pressure in the autoclave under a condition of water existence, rising the temperature so as to pre-polymerize, and then preparing high viscosity semi-aromatic polyamide resin by performing tackifying reaction on the pre-polymerized materials. The method of the invention prepares the semi-aromatic polyamide by applying nitrogen pressure, the diamine loss is avoided and the mole ratio of the dicarboxylic acid and the diamine can be accurately controlled so as to acquire the high viscosity semi-aromatic polyamide. The pre-polymerized material which has a viscosity eta ranged from 0.06 to 0.3 dl / g tested in 96% sulfuric acid at 25 DEG C by performing the pre-polymerization reaction is acquired. After the tackifying reaction is performed, the viscosity eta of the semi-aromatic aromatic polyamide is ranged from 0.8 to 2.5 dl / g, the melting point of the semi-aromatic aromatic polyamide is ranged from 270 to 330 DEG C, the content of the end carboxyl is ranged from 15 to 80 mol / t and the content of the end amino is ranged from 15 to 80 mol / t.

Description

technical field [0001] The invention relates to the preparation technology of semi-aromatic polyamide. Background technique [0002] Aliphatic polyamides, such as PA6 and PA66, have excellent mechanical strength, heat resistance, chemical resistance, wear resistance and self-lubricating properties, and low coefficient of friction. Their applications include electronic appliances, automotive parts, furniture , building materials and fibers, has become one of the most important engineering plastics. [0003] Semi-aromatic polyamide is a polyamide resin prepared by polycondensation of diamines or dicarboxylic acids with aromatic rings and aliphatic dicarboxylic acids or diamines, and is one of the aromatic polyamides. Due to the introduction of aromatic rings into the main chain of polyamide molecules, the heat resistance and mechanical properties are improved, the water absorption rate is reduced, and it has a more suitable performance / price ratio. It is between general engin...

AI Technical Summary

Problems solved by technology

Increasing the pre-polymerization temperature will lead to the occurrence of side reactions, and will also increase the reaction pressure, and the requirements for equipment will also increase accordingly

Draining the water in the reaction will volatilize the unreacted diamine, resulting in a large difference between the monomer unit ratio of the prepolymer and the initial monomer ratio added to the reactor, and it cannot guarantee that the monomer dicarboxylic acid and Molar ratio balance of diamines

[0011] The amine group value of the semi-aromatic polyamide obtained by the existing preparation method is much lower than the carboxyl group value, which has adverse effects on the application of the product