Hexamethylenediammonium adipate

Nylon 66 is produced by the reaction of hexamethylenediamine and adipic acid (see Chapters 9 and 10 for the production of the two monomers). This produces hexamethylenediammonium adipate salt. The product is a dilute salt solution concentrated to approximately 60% and charged with acetic acid to a reactor where water is continuously removed. The presence of a small amount of acetic acid limits the degree of polymerization to the desired level ... 

Preparation of Polyamide-6,6 from Hexamethylenediammonium Adipate (AH Salt) by Condensation in the Melt... 

The reaction between adipic acid and hexamethylene diamine produces hexamethylenediammonium adipate, commonly called nylon salt (Fig. 1) Forming the salt assures the correctly balanced proportions. It is also necessary that the material to be polymerized contain very few impurities if high-quality fibers are to be made by a variety of routes (Fig. 2). 

In amidation, equilibrium is favorable even in the presence of water. In order to avoid loss of diamine in the early stages of pol3unerization with a resultant imbalance, the first step of pol3onerization is carried out under pressure at elevated temperature. Hexamethylenediammonium adipate with or without water is heated in a closed reactor at about 200°C and autogeneous pressure. Reaction takes place to form amide links and water and proceeds far enough to fix at least one end of all reactants. The steam pressure is then bled off and the temperature raised to 260-300 C to finish the reaction and produce high-molecular-weight polymer. 

Hexamethylenediammonium adipate. See Hexamethylenediamine adipate Hexamethylene diisocyanate CAS 822-06-0 EINECS/ELINCS 212-485-8 UN 2281 (DOT)... 

Nylon-6/6 salt (hexamethylenediammonium adipate) n. An intermediate in the manufacture of nylon-6/6, formed from one molecule each of adipic acid and hexam-ethylene diamine. 

Thus in the production of nylon 6,6, the first step consists of the neutralization of an aqueous solution of adipic acid by addition of hexamethyl-enediamine the exact end-point is determined electrometrically. The aqueous salt solution is then concentrated to 60—75% solids content before transfer to the polymerization reactor. In an alternative procedure, approximately equivalent quantities of adipic acid and hexamethylenediamine are mixed in boiling methanol, from which the 1 1 salt is precipitated. The salt is isolated by filtration and then dissolved in water and the solution fed to the polymerization reactor. The nylon salt, hexamethylenediammonium adipate may be represented as follows ... 

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