Process for producing a semi-aromatic semi-crystalline polyamide

Patent metadata

Field	Value
Publication number	US-9556310-B2
Application number	US-201414899404-A
Country	US
Kind code	B2
Filing date	Jun 16, 2014
Priority date	Jun 19, 2013
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

The invention relates to a process for the preparation of semi-crystalline semi-aromatic polyamide by direct solid-state polymerization of a diamine-dicarboxylic acid salt, comprising steps of (a) providing at least two salts of terephthalic acid and diamine, wherein each of these diamine/terephthalic acid salts is in solid state and has a melting temperature of at least Tx, wherein Tx is at least 260° C.; (b) preparing a mixture of the diamine/terephthalic acid salts, while retaining the salts in solid state; and (c) heating the mixture obtained from step (b) in the solid state to a temperature (T-c) in the range from 200° C. to 260° C., under a pressure below the saturation vapor pressure of water at said temperature, thereby condensing and polymerizing the salts and forming a semi-crystalline semi-aromatic polyamide in solid form.

First claim

The invention claimed is:

1. A process for the preparation of semi-crystalline semi-aromatic polyamide by direct solid-state polymerization of a solid-state diamine-dicarboxylic acid salt mixture, comprising steps of:
(a) providing at least two salts of terephthalic acid and diamine, wherein each of the at least two salts of terephthalic acid and diamine is in a solid state and has a melting temperature (Tx) of at least 260° C.;
(b) preparing a solid state salt mixture of the at least two salts of terephthalic acid and diamine by mixing the at least two salts of terephthalic acid and diamine while maintaining the at least two salts in the solid state;
(c) conducting solid state polymerization of the solid state salt mixture obtained from step (b) by heating the solid state salt mixture to a temperature (T-c) in the range from 200° C. to Tx and under a pressure below saturation vapour pressure of water at said temperature while maintaining the salt mixture in the solid state to condense and polymerize the at least two salts and thereby form a semi-crystalline semi-aromatic polyamide in a solid state directly from the solid state salt mixture, wherein
steps (b) and (c) are practiced in the absence of a dispersing agent or solvent.

2. The process according to claim 1 , wherein step (c) comprises heating the salt mixture obtained from step (b) in the solid state to a temperature (T-c) in the range from 200° C. to 260° C.

3. The process according to claim 1 , wherein each of the least two salts of terephthalic acid and diamine has a melting temperature of at least 280° C., and wherein step (c) comprises heating the salt mixture obtained from step (b) in the solid state to a temperature (T-c) in the range from 220° C. to 280° C.

4. The process according to claim 1 , wherein the diamines in the at least two salts of terephthalic acid and diamine are selected from C2-C12 diamines.

5. The process according to claim 1 , wherein the at least two salts of terephthalic acid and diamine comprise:
a first salt (A) of terephthalic acid and a first diamine, and
a second salt (B) of terephthalic acid and a second diamine, wherein the first diamine and the second diamine are different diamines, and wherein each of the first diamine and the second diamine is a C2-C10 diamine.

6. The process according to claim 5 , wherein the at least two salts of terephthalic acid and diamine comprise:
2.5-97.5 mol % of the first salt (A) of terephthalic acid and the first diamine, and
97.5-2.5 mol % of the second salt (B) of terephthalic acid and the second diamine, wherein
the mol % is relative to the total molar amount of the at least two salts of terephthalic acid and diamine in the salt mixture.

7. The process according to claim 5 , wherein the salt mixture terephthalic acid and diamine comprises at least one additional salt (C) of terephthalic acid and a third diamine other than the first diamine and the second diamine.

8. The process according to claim 5 , wherein the salt mixture consists of:
5-95 mol % of the first salt (A) of terephthalic acid and the first diamine,
5-95 mol % of the second salt (B) of terephthalic acid and the second diamine, and
0-35 mol % of the third salt (C) of terephthalic acid and the third diamine, wherein
the mol % is relative to the total molar amount of salts of terephthalic acid and diamine in the salt mixture.

9. The process according to claim 4 , where the C2-C10 diamine is selected from the group consisting of linear aliphatic diamines, branched aliphatic diamines, cycloaliphatic diamines and arylalkylamines.

10. The process according to claim 1 , wherein at least one diamine is selected from the group consisting of C2-C8 diamines.

11. The process according to claim 1 , wherein the at least two salts of terephthalic acid diamine are in the form of a powder.

12. The process according to claim 1 , wherein step (c) comprises increasing the temperature above 200° C. at a heating rate of at most 5° C. per minute.

13. The process according to claim 1 , wherein step (c) comprises keeping the temperature of the mixture at the temperature (T-c) for at least 1 hour in the range from 210° C. to Tx−5° C.

14. The process according to claim 1 , wherein the semi-aromatic semi-crystalline polyamide obtained in step (c) has a viscosity number of at least 15.

15. The process according to claim 1 , which further comprises the step of:
(d) subjecting the semi-aromatic polyamide obtained from step (c) to a solid-state post-condensation step by heating the semi-aromatic polyamide, having a melting temperature Tm-pol which is above Tx, to a temperature (T-d) above Tx and at least 10° C. below Tm-pol, thereby further polymerizing the semi-aromatic polyamide and obtaining a semi-aromatic polyamide of higher molecular weight.

16. The process according to claim 1 , wherein step (c) is carried out in a reactor, and comprises (i) releasing water produced as water vapour during step (c) upon condensing of the salts, and diamine as diamine vapour from at least one of the salts of terephthalic and diamine, (ii) at least partly separating the water and diamine vapor from each other thereby forming a water-rich fraction and a diamine-rich fraction, and (iii) removing the water-rich fraction from the reactor and retaining the diamine-rich fraction in the reactor or recycling the diamine-rich fraction into the reactor.

Assignees

• Dsm Ip Assets Bv

Inventors

• Rulkens Rudy
• Grolman Eric
• Vanden Poel Geert Adelina Rudolf
• Kierkels Renier Henricus Maria
• Cuypers Theo Joseph
• Papaspyrides Constantine D
• Porfyris Athanasios D

Classifications

• C08L77/00

  Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain (of polyhydrazides C08L79/06; of polyamideimides or polyamide acids C08L79/08); Compositions of derivatives of such polymers · CPC title

• C08G69/30 Primary

  Solid state polycondensation · CPC title

• C08L77/06

  Polyamides derived from polyamines and polycarboxylic acids (C08L77/10 takes precedence) · CPC title

• C08G69/265 Primary

  from at least two different diamines or at least two different dicarboxylic acids · CPC title