PROCESS FOR PREPARING PA-4X, AND PA-410 OBTAINABLE BY THE PROCESS

摘要

A process for preparation of a polyamide PA-4X containing monomer units of 1,4-diaminobutane and an aliphatic linear dicarboxylic acid X with at least 8 carbon atoms, which contains the following steps: 1) making a solution comprising a salt of 1,4-diaminobutane and the aliphatic linear dicarboxylic acid and water, at a temperature at which the salt dissolves; 2) concentrating the solution of the salt at a temperature above the crystallization temperature of the salt, at a pressure of at most 7 barA to a water content of between 0.01 and 30 wt.% based on the total amount of solution; 3) producing a polymer from the solution obtained by step 2, while keeping the polymer in a melt and at a pressure of less than 18 barA; 4) depressurizing the polymer obtained at step 3 while keeping the polymer in the melt to further polymerize the polymer. In an preferred embodiment the aliphatic linear dicarboxylic acid is 1,10-decanedioic acid. Also claimed is a polyamide 410 having a viscosity number (VN) of at least 105 ml/gram, measured in accordance with ISO 307, Fifth edition 2007-05-15, in formic acid (c=0.005 g/mL).