Patent ID: 9453107
Filing Date: 2016-09-27
CPC Classification: B01J,B29B,B29C,C08G

Claim Text:
1. A method for preparing a polyamide by polycondensation from one or several monomers adapted for preparing a polyamide characterized in that: the selected monomer(s) are introduced without any preliminary reaction and without any preliminary preparation of the corresponding salt, into an extruder including at least two conveying screws rotating co-rotatively, all the reaction and polycondensation steps, initially starting with the selected monomer(s), and giving the possibility of ending up with the desired polyamide, are conducted in a single extruder including at least two conveying screws rotating co-rotatively, polycondensation is achieved by carrying out at least two operations for discharging the formed by-product(s) by the polycondensation reaction, and in that it includes the following successive steps: a step for mixing the selected monomer(s), a polycondensation step conducted by successively carrying out shearing and depressurization operations on the material conveyed by the conveying screws, a step for forming a plug of material continuously renewed by conveyance of the material on the conveying screws, between the mixing and polycondensation steps; said material plug consisting of the advancing material filling the whole space available for the passage of the material and forming an area which is hermetic to vapors, including monomer vapors which may be generated, wherein the obtained polyamide has a viscosity index at least equal to 80 ml/g.