Process for preparing nylon salt and its polymerization

Patent metadata

Field	Value
Publication number	US-11306181-B2
Application number	US-202016779364-A
Country	US
Kind code	B2
Filing date	Jan 31, 2020
Priority date	Jul 29, 2014
Publication date	Apr 19, 2022
Grant date	Apr 19, 2022

Abstract

The present invention relates to a process for preparing a granular nylon salt material, wherein an aqueous mixture, comprising at least 65 wt. % of salt components, and at most 35 wt. % of an aqueous medium, the weight percentages (wt. %) being relative to the total weight of the aqueous mixture, is flashed from a pressure vessel via a flash valve into a flash chamber, thereby evaporating the aqueous medium in an amount sufficient to result in a residual moisture content of at most 7.5 wt. %, and forming a granular nylon salt material. The invention also relates to a process for preparing a nylon polymer, comprising direct solid state polymerization of the granular salt material prepared by flash granulation.

First claim

The invention claimed is:

1. A process for preparing a nylon polymer, wherein the process comprises:
(a) providing a diammonium dicarboxylate salt which is a granular salt material prepared by flash granulation at a temperature Tp of at least 150° C. to 230° C., and
(b) conducting direct solid state polymerization (DSSP) of the diammonium dicarboxylate salt.

2. The process of claim 1 , wherein the granular salt material is a granular nylon salt.

3. The process according to claim 2 , wherein the granular nylon salt is prepared by the steps comprising:
(a) providing in a pressure vessel a concentrated aqueous mixture comprising at least 65 wt. % of salt components and at most 35 wt. % of an aqueous medium, the weight percentages (wt. %) being relative to the total weight of the aqueous mixture;
(b) controlling temperature of the concentrated aqueous mixture in the pressure vessel so that the concentrated aqueous mixture has the temperature Tp of at least 150° C. to 230° C.;
(c) controlling pre-condensation eventually occurring in the concentrated aqueous mixture so that pre-condensation therein remains at a level of at most 15 mole %; and
(d) discharging the concentrated aqueous mixture from the pressure vessel by flashing the concentrated aqueous mixture at the temperature Tp of 150° C. to 230° C. via a flash valve into a flash chamber to evaporate the aqueous medium in an amount sufficient to result in a residual moisture content of at most 7.5 wt. % and thereby directly form forming a granular nylon salt material, wherein the wt. % of the residual moisture content is relative to the weight of the granular nylon salt material.

4. The process according to claim 3 , wherein the concentrated aqueous mixture is:
(i) an aqueous solution comprising a diamine, or a mixture of at least two diamines, and a dicarboxylic acid, or a mixture of at least two dicarboxylic acids, all together referred to as salt precursors, dissolved in the aqueous medium; or
(ii) an aqueous slurry comprising a diammonium dicarboxylate salt dispersed in the aqueous medium.

5. The process according to claim 3 , wherein the concentrated aqueous mixture is an aqueous solution prepared by:
dissolving salt precursors in an aqueous medium, using an excess of the aqueous medium, thereby obtaining a diluted solution; and
evaporating the excess of the aqueous medium at elevated temperature and elevated pressure, thereby obtaining a pressurized concentrated solution.

6. The process according to claim 3 , wherein the concentrated aqueous mixture is an aqueous solution prepared by:
providing a slurry comprising salt components dispersed in an aqueous medium in a pressure vessel; and
closing the pressure vessel and heating the slurry in the pressure vessel to elevated temperature thereby increasing the pressure in the pressure vessel, dissolving the salt components and obtaining a pressurized concentrated solution.

7. The process according to claim 3 , wherein the concentrated aqueous mixture is a concentrated aqueous slurry directly obtained from an aqueous solution comprising salt precursors dissolved in the aqueous medium.

8. The process according to claim 7 , wherein the concentrated aqueous slurry is prepared by:
preparing an aqueous solution by dissolving salt precursors in an aqueous medium; and
concentrating the aqueous solution by evaporating the aqueous medium in an amount sufficient to result in partial precipitation of diammonium/dicarboxylate salt, thereby obtaining the concentrated aqueous slurry comprising salt particles dispersed in the aqueous medium.

9. The process according to claim 3 , wherein step (d) is practiced by flashing the concentrated aqueous mixture such that the aqueous medium is evaporated in an amount sufficient to result in a residual moisture content of at most 5.0 wt. %, relative to the weight of the granular nylon salt material.

10. The process according to claim 3 , wherein the aqueous medium consists of water.

11. The process according to claim 3 , wherein the aqueous medium is present in an amount of at most 20 wt. %, relative to the total weight of the aqueous mixture, and wherein the temperature Tp is in a range from 150° C. to 170° C.

12. The process according to claim 3 , wherein the aqueous medium is present in an amount of at most 25 wt. %, relative to the total weight of the aqueous mixture, and wherein the temperature while Tp is in a range from 170° C. to 190° C.

13. The process according to claim 3 , wherein the aqueous medium is present in an amount of at most 30 wt. %, relative to the total weight of the aqueous mixture, and wherein the temperature while Tp is in a range from 190° C. to 210° C.

14. The process according to claim 3 , wherein the aqueous medium is present in an amount of at most 35 wt. %, relative to the total weight of the aqueous mixture, and wherein the temperature while Tp is in a range from 210° C. to 230° C.

15. The process according to claim 3 , wherein the nylon salt is an aliphatic salt, the salt components therein being all aliphatic components, comprising an aliphatic diamine, or a mixture of at least two aliphatic diamines, and an aliphatic dicarboxylic acid, or a mixture of at least two aliphatic dicarboxylic acids, and wherein the aqueous medium is present in an amount of at most 20 wt. %, relative to the total weight of the aqueous mixture, and wherein the temperature Tp is in a the range from 150° C. to 170° C.

16. The process according to claim 3 , wherein the nylon salt is a semi-aromatic salt.

17. The process according to claim 16 , wherein the semi-aromatic salt comprises terephthalic acid.

18. The process according to claim 1 , wherein the granular salt material is in a form of compressed pellets made of the diammonium dicarboxylate salt.

Assignees

• Dsm Ip Assets Bv

Inventors

• Van Laarhoven Bas
• Grolman Eric
• Muyris Michiel

Classifications

• C08G69/26

  derived from polyamines and polycarboxylic acids · CPC title

• B01J2/02

  by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops · CPC title

• C08G69/28 Primary

  Preparatory processes · CPC title

• C08G69/30 Primary

  Solid state polycondensation · CPC title

• C07C63/28

  Salts thereof · CPC title