Dsm IP Assets B.v.

Ronald Ligthart

Pieter Gijsman

Pim Gerard Anton Janssen

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 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 100 ml/gram.

Process for preparing PA-4X, and PA-410 obtainable by the process

A process for the production of a polymer containing monomer units of butane-1,4-diamine and 1,10-decanedioic acid (PA-410) having a viscosity number (VN) of at least 105 ml/gram includes making a solution of a salt of butane-1,4-diamine and 1,10-decanedioic acid in water, concentrating the solution of the salt at a temperature of between 100 and 180&#xb0; C. and a pressure of between 1.0 and 3.0 bar to a water content of between 4 and 8 wt %, producing a prepolymer from the salt containing monomer units of butane-1,4-diamine and 1,10-decanedioic acid at a temperature of between 185 and 205&#xb0; C., and thereafter subjecting the prepolymer to post condensation.

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Ronald Ligthart