Rhodia Operations

Other

Rhone-poulenc Chimie

Rhodianyl

Jean-Francois Thierry

Matthieu Helft

Sébastien Lomel

Sebastien Lomel

Pierre-Yves Lahary

Vincent Mollet

Virginie Thieblemont

Daniel Brun

Phlippe Boulanger

Véronique Bossennec

Cédric Fillon

Veronique Bossennec

Cedric Fillon

The present invention relates to a method for preparing polyamide granules. This method comprises, in particular, steps of extruding the polymer, cooling and cutting the extruded material, and a step of cooling the granules. The method of the invention is simple and quick to implement.

Method for preparing polyamide granules

A method for manufacturing a solution of a diacid and diamine salt for manufacturing polyamide is described. A method for manufacturing an aqueous solution of diacid and diamine salts produced by mixing at least two diacids and at least one diamine, with a weight concentration of salt between 40% and 70%, including, in a first step, preparing an aqueous solution of diacid(s) and diamine(s) with a diacid/diamine mole ratio of less than 1 using one diacid and one diamine, and in a second step, adjusting the mole ratio of diacids/diamine(s) to a value of between 0.9 and 1.1, and fixing the weight concentration of salt by adding another diacid and, optionally, additional water and/or diamine is also described.

Process for the manufacture of a solution of salts of diacids/diamine(s)

Polyamides, e.g., polyhexamethylene adipamide, are continuously produced via the following stages:

Continuous production of polyamides

A method for making polyamide is described. More particularly, a method for making a polyamide from at least one diacid and one diamine, that includes a step of concentrating an aqueous solution of diacid and diamine salt up to a salt weight concentration higher than 85%, and a polymerization step up to a desired polymerization degree is described.

Polyamide manufacturing process

The invention relates to a continuous process for manufacturing polyamides. The polyamides are of the type obtained from diacids and diamines. The process comprises an operation of continuous mixing of a compound which is rich in amine end groups and a compound which is rich in acid end groups and a polycondensation operation using the mixture. The invention relates to the starting phase of such a process, during which an aqueous solution comprising a mixture of monomers in substantially stoichiometric proportions is used.

Process for manufacturing polyamides

The invention concerns a method for making polyamide. More particularly, the invention concerns a method for making polyamides derived from the reaction between a diacid and a diamine. It concerns a method for making a polyamide derived from the reaction of at least a diacid with at least a polyamide comprising the following steps: preparing a first mixture of diacid and diamine with a diacid/diamine molar ratio ranging between 0.8 and 0.995, preferably ranging between 0.95 and 0.99 in a first reactor ( ); preparing a second mixture of diacid and diamine with a diacid/diamine molar ratio ranging between 1.005 and 1.2, preferably between 1.01 and 1.05, in a second reactor ( ); introducing in melted form a first flow of the first mixture and a second flow of the second mixture in a stirred polymer reactor ( ); drawing, preferably, continuously, from said reactor a flow of polyamide prepolymer; feeding said polyamide flow into a finishing step to obtain the desired degree of polymerisation. The invention is characterised in that the stoichiometry of the polyamide in the reactor ( ) or the acid function/amine function ratios in the different reactors are measured by near infrared spectrometric analysis, and by controlling the feed flows in the different reactors using the results of said analyses.

Method for making polyamides

L-aspartic acid is improvedly prepared in high yields by treating ammonium aspartate, advantageously in aqueous reaction medium, with an effective, aspartic acid-precipitating amount of fumaric acid.

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Francheville, France

Jean-Francois Thierry