Process for enriching the difunctional content of (per) fluopolyether mixtures

Patent metadata

Field	Value
Publication number	US-9145471-B2
Application number	US-201214354424-A
Country	US
Kind code	B2
Filing date	Oct 23, 2012
Priority date	Oct 28, 2011
Publication date	Sep 29, 2015
Grant date	Sep 29, 2015

Abstract

The present invention relates to a process for increasing the content of bifunctional species in mixtures of non functional, mono- and bifunctional (per)fluoropolyethers which comprises the adsorption of a (per)fluoropolyether mixture onto an adsorbing stationary phase, a first desorption step with a supercritical fluid only and a second desorption step with the supercritical fluid and a mixture of a polar solvent.

First claim

The invention claimed is:

1. A process for increasing the content of bifunctional species in mixtures of non functional, mono- and bifunctional (per)fluoropolyethers which comprises the following steps:
(a) adsorbing a mixture (M) of non functional, mono- and bifunctional (per)fluoropolyethers having a first average functionality (F1) onto an adsorbing stationary phase;
(b) desorbing mixture (M) with a supercritical fluid to recover a (per)fluoropolyether mixture (M′) having a second average functionality (F2) lower than functionality (F1);
(c) desorbing the remaining mixture (M) with the supercritical fluid in admixture with a polar solvent to recover a (per)fluoropolyether mixture (M″) having a third average functionality (F3) higher than functionality (F1).

2. A process according to claim 1 , wherein mixture (M) complies with formula:
X 1 —O—R f —Y  (I)

wherein:
R f is a (per)fluoropolyoxyalkylene chain having a number average molecular weight ranging from 500 to 10,000 and comprising repeating units selected from —CF 2 O—, —CF 2 CF 2 O—, —CF 2 CF 2 CF 2 O—, —CF 2 CF 2 CF 2 CF 2 O—, —CF 2 CF(CF 3 )O—, —CF(CF 3 )CF 2 O— and —CR 4 R 5 CF 2 CF 2 O— wherein R 4 and R 5 are equal to or different from each other and are selected from H, Cl and fully or partially fluorinated alkyl, said repeating units being statistically distributed along the chain;
X 1 is selected from: —CFXCH 2 O(CH 2 CH 2 O) s H, —CFXC(O)R h , —CFXC(O)OR h , —CFXC(O)NR h I R h II , —CFXCH 2 O(CH 2 CH 2 O) s P(O)(OR h I )(OR h II ), in which s ranges from 0 to 20, X is F or CF 3 , R h , R h I and R h II are independently selected from H and a C 1 -C 10 straight or branched alkyl group,
Y is the same as X 1 or is selected from —CF 3 , —CF 2 Cl, —CF 2 CF 2 Cl, —C 3 F 6 Cl, —CF 2 Br, —CF 2 CF 3 , —CF 2 H, —CF 2 CF 2 H.

3. A process according to claim 2 , wherein chain R f is selected from:
a chain of formula:
—(C 3 F 6 O) a (CFXO) b —  (Ia)

wherein —C 3 F 6 O— represents units of formulae —CF(CF 3 )CF 2 O— and —CF 2 CF(CF 3 )O—, X is as defined above, a is an integer equal to or higher than 1 and b is 0 or an integer equal to or higher than 1, selected in such a way that the number average molecular weight of chain R f is in the above-defined range and that, when b is other than 0, the a/b ratio ranges from 10 to 100; and

a chain of formula:
—(CF 2 CF 2 O) c (CF 2 O) d [CF 2 (CF 2 ) z O] h —  (Ib)

in which c is an integer equal to or higher than 1, d and h are 0 or integers equal to or higher than 1, c, d and h being selected in such a way that the number average molecular weight of chain R f is in the above range and that, when d is an integer equal to or higher than 1, the c/d ratio ranges from 0.1 to 10, the h/(c+d) ratio ranges from 0 to 0.05 and z is 2 or 3.

4. A process according to claim 3 , wherein chain R f is a chain of formula —(CF 2 CF 2 O) c (CF 2 O) d [CF 2 (CF 2 ) z O] h — (Ib), X 1 is selected from —CFXCH 2 O(CH 2 CH 2 O) s H, —CFXC(O)OR h , and —CFXC(O)NR h I R h II .

5. A process according to claim 1 , wherein functionality (F3) is at least 1.985.

6. A process according to claim 1 , wherein the adsorbing stationary phase is selected from silica gels, aluminium and magnesium silicates, active alumina, metal oxides, metal hydroxides and barium sulphate.

7. A process according to claim 6 , wherein the adsorbing stationary phase is a silica gel.

8. A process according to claim 1 , wherein the supercritical fluid is selected from carbon dioxide, acetone and a hydrocarbon.

9. A process according to claim 8 , wherein the supercritical fluid is carbon dioxide.

10. A process according to claim 1 , wherein the polar solvent is an alcohol.

11. A process according to claim 10 , wherein the polar solvent is selected from methanol, ethanol, propanol and trifluoroethanol.

12. A process according to claim 11 , wherein the polar solvent is methanol.

Assignees

• Solvay Specialty Polymers It

Inventors

• Tonelli Claudio Adolfo Pietro
• Valsecchi Roberto
• Mutta Fabrizio

Classifications

• C08G65/30 Primary

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

• C08G65/46

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

• C08G65/007

  containing fluorine · CPC title

• C08G65/48 Primary

  Polymers modified by chemical after-treatment · CPC title

• Y02P20/54

  using solvents, e.g. supercritical solvents or ionic liquids · CPC title