Process for the purification of (per) fluoropolyethers with carboxylate end groups

Patent metadata

Field	Value
Publication number	US-9370733-B2
Application number	US-201314440821-A
Country	US
Kind code	B2
Filing date	Oct 30, 2013
Priority date	Nov 5, 2012
Publication date	Jun 21, 2016
Grant date	Jun 21, 2016

Abstract

The invention relates to a batch chromatography process the purification of (per)fluoropolyether (PFPE) carboxylates, in particular to a process for increasing the average functionality of PFPE carboxylates mixtures.

First claim

The invention claimed is:

1. A batch chromatography process for the purification of (per)fluoropolyethers (PFPE) carboxylates, the process comprising:
a) contacting a mixture (M) of non-functional PFPEs and functional PFPEs carboxylates wherein Mn of the (per)fluoropolyoxylakylene chain in the PFPE carboxylate is equal to or higher than 1,500, said mixture (M) having functionality (F), with a solid phase and a fluorinated organic solvent at ambient conditions to obtain a suspension (S) of a solid phase having adsorbed onto it a mixture (M1) of functional PFPE carboxylates with functionality (F1) higher than (F) and a liquid phase having therein dissolved a mixture (M2) with functionality (F2) lower than (F);
b) separating the liquid phase from the solid phase;
c) optionally carrying out one or more washings of the solid phase with the same fluorinated solvent as used in step a);
d) adding the solid phase with a mixture of an alcohol and a fluorinated organic solvent to obtain a suspension (S2) of the solid phase in a liquid phase, said liquid phase having mixture (M1) therein dissolved;
e) separating the liquid phase from the stationary phase.

2. The process according to claim 1 , wherein the (per)fluoropolyether mixture (M) complies with formula (I) below:
A-O—R f —B  (I)

wherein:
A and B, equal to or different from one another, are functional groups of formula —CFXCOOH in which X is F or CF 3 , or non-functional straight or branched C 1 -C 4 perfluoroalkyl groups wherein one fluorine atom can be substituted by one chlorine atom or one hydrogen atom; provided that, when chlorine is present in a non-functional group A or B, it is in a molar amount lower than 2% with respect of the non-functional group;
R f is a (per)fluoropolyoxylakylene chain having a number average molecular weight higher than 1,500 and lower than 15,000, said chain containing repetitive units, which may be equal to or different from one another, selected from the group consisting of: (CFYO), wherein Y is F or CF 3 ; (CF 2 CF 2 O); (C 3 F 6 O); (CF 2 CF 2 CF 2 O); (CF 2 CF(CF 3 ); (CF(CF 3 )CF 2 O); and (CF 2 CF 2 CF 2 CF 2 O); when the repetitive units are different from one another, they are statistically distributed along the chain.

3. The process according to claim 2 , wherein R f is selected from the following classes:
—(CF 2 O) n (CF 2 CF 2 O) m (CF 2 CF 2 CF 2 O) p (CF 2 CF 2 CF 2 CF 2 O) q -  (a)

wherein m, n, p, q are 0 or integers selected such that R f has a Mn equal to or higher than 1,500;
—(CF 2 CF(CF 3 )O) a (CF 2 CF 2 O) b (CF 2 O) c (CF(CF 3 )O) d —  (b)

wherein a, b, c, d are 0 or integers selected such that R f has a Mn equal to or higher than 1,500; and
—(CF 2 CF(CF 3 )O) e (CF 2 O) f (CF(CF 3 )O) g —  (c)

wherein e, f, g are 0 or integers selected such that R f has a Mn equal to or higher than 1,500.

4. The process according to claim 2 , wherein the mixture of formula (I) is a mixture wherein the amount of PFPE carboxylic acid in which one of A and B is the —CFXCOOH group and the other one is the non-functional straight or branched C 1 -C 4 perfluoroalkyl group, and wherein the amount of PFPE carboxylic acid is higher than the amount of PFPE carboxylic acid wherein both A and B are a —CFXCOOH group.

5. The process according to claim 4 , wherein chain R f belongs to class (a) or (c):
—(CF 2 O) n (CF 2 CF 2 O) m (CF 2 CF 2 CF 2 O) p (CF 2 CF 2 CF 2 CF 2 O) q -  (a)

wherein m, n, p, q are 0 or integers selected such that R f has a Mn equal to or higher than 1,500; or
—(CF 2 CF(CF 3 )O) e (CF 2 O) f (CF(CF 3 )O) g —  (c)

wherein e, f, g are 0 or integers selected such that R f has a Mn equal to or higher than 1,500.

6. The process according to claim 2 , wherein the mixture of formula (I) is a mixture wherein the amount of PFPE carboxylic acid in which both A and B are the —CFXCOOH group is higher than the amount of PFPE carboxylic acid in which one of A and B is the —CFXCOOH group the other one is the non-functional straight or branched C 1 -C 4 perfluoroalkyl group.

7. The process according to claim 6 , wherein chain R f belongs to class (a) or (b):
—(CF 2 O) n (CF 2 CF 2 O) m (CF 2 CF 2 CF 2 O) p (CF 2 CF 2 CF 2 CF 2 O) q -  (a)

wherein m, n, p, q are 0 or integers selected such that R f has a Mn equal to or higher than 1,500;
—(CF 2 CF(CF 3 )O) a (CF 2 CF 2 O) b (CF 2 O) c (CF(CF 3 )O) d —  (b)

wherein a, b, c, d are 0 or integers selected such that R f has a Mn equal to or higher than 1,500.

8. The process according to claim 1 , wherein the fluorinated organic solvent is selected from trichlorotrifluoroethene; non-functional fully or partially fluorinated PFPEs; perfluoroalkanes; hydrofluorocarbons (HFCs); hydrofluoroethers; hydrofluoropolyethers and fully or partially fluorinated aromatic solvents.

9. The process according to claim 8 , wherein the fluorinated solvent is selected from 1,3-bis(trifluoromethyl)benzene, mixtures of ethyl nonafluoroisobutyl ether and ethyl nonafluoro-n-butyl ether, and 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane.

10. The process according to claim 1 , wherein the alcohol is selected from methanol and ethanol.

11. The process according to claim 10 , wherein the alcohol is methanol.

12. The process according to claim 1 , wherein the solid phase is selected from silica gel, Al and Mg silicates and active alumina.

13. The process according to claim 12 , wherein the solid phase is silica gel.

14. The process according to claim 1 , wherein step d) comprises adding the solid phase with a mixture of an alcohol and a fluorinated organic solvent to obtain a suspension (S1) and heating to obtain a suspension (S2) of the solid phase in a liquid phase, said liquid phase having mixture (M1) therein dissolved.

15. The process according to claim 3 , wherein m/n is between 0.1 and 20, extremes included, when m is other than 0; and wherein (p+q)/(m+n) is between 0 and 0.2, extremes included, when (m+n) is other than 0.

16. The process according to claim 3 , wherein a/b is between 0.1 and 10 when b is other than 0; and wherein (c+d)/(a+b) is between 0.01 and 0.5 when (a+b) is other than 0.

17. The process according to claim 3 , wherein (f+g)/e is between 0.01 and 0.5 when e is other than 0.

Assignees

• Solvay Specialty Polymers It

Inventors

• Fontana Simonetta Antonella
• Guarda Pier Antonio

Classifications

• C08G65/30

  Post-polymerisation treatment, e.g. recovery, purification, drying · CPC title

• C08G2650/48

  containing fluorine, e.g. perfluropolyethers · CPC title

• B01D15/424 Primary

  Elution mode · CPC title

• C08G65/007

  containing fluorine · CPC title

• B01D15/08

  Selective adsorption, e.g. chromatography · CPC title