PA66 (nylon 66) is a very important chemical product what can be used in many different areas, especially in the production of synthetic fibers and engineering plastics, such as modified plastics, civil wire and carpet yarn etc,.
Generally, PA66 was made of adipic acid or 1,6-Hexanediamine, while the 1,6-Hexanediamine is mainly produced by hydrogenation of adiponitrile, so the production of adiponitrile is a crucial part and a core raw material in the upstream process.
So, how to get adiponitrile?The synthesis of adiponitrile includes ADA, AN, and BD. But ADA has no advantage in cost and production has been stopped on the market.
This production process was successfully developed by Ronald Planck of France in the 1960s. After that, BASF, Radici and China's Liaoyang Petrochemical mainly used this method to make adiponitrile.
But later, due to the price increase of adipic acid, this production has no cost advantage compared with the method with butadiene (ADA is about 38% higher than that of butadiene), resulting in the discontinuation of the traditional plant of Radici and Liaoyang Petrochemical.
The process was developed by Monsanto Company in the 1970s which gradually evolved from diaphragm electrolysis to diaphragmless electrolysis. The reaction process only needs one step. The product is easily to be refined and purified, but the reaction conditions need to be strictly controlled. Influenced by factors such as pH and current density, equipment investment is relatively high and power consumption is large.
At present, companies that have mastered the technology of adiponitrile production include Asahi Kasei, Oscar, and BASF in Germany. It is estimated that the cost of this method is higher than that of butadiene, which is $800/ton.
The butadiene method is divided into butadiene chlorination cyanide method and butadiene direct cyanidation method. The butadiene chlorination cyanidation method was first developed by DuPont from the United States (now INVISTA) in the early 1960s. This method has already been abandoned due to its complicated process, serious corrosion , and large investment .
The current mainstream is the direct cyanidation process, which was invented by DuPont in the early 1970s and is currently dominated by Invista and BASF.