POLYVINYLIDENE FLUORIDE SOLUTIONS IN N-FORMYL- OR N-ACETYLMORPHOLINE

Abstract

Solutions of polyvinylidene fluoride (PVDF) or copolymers of 1,1-difluoroethylene in a solvent which comprises N-formylmorpholine (NFM), N-acetylmorpholine (NAM) or mixtures thereof and additionally a cosolvent selected from alkylene carbonate, mono-, di- or polyalkylene glycol dialkyl ethers or mixtures thereof.

Claims

1. A solution of a polyvinylidene fluoride or a copolymer of 1,1-difluoroethylene in a solvent, said solution comprising: N-formylmorpholine, N acetylmorpholine, or mixtures thereof; and a cosolvent selected from the group consisting of an alkylene carbonate, a mono-alkylene glycol dialkyl ether, a di-alkylene glycol dialkyl ether, a polyalkylene glycol dialkyl ether, and mixtures thereof.

2. The solution according to claim 1, wherein the cosolvent is a mono-alkylene glycol dialkyl ether, a di-alkylene glycol dialkyl ether, or a polyalkylene glycol dialkyl ether of the formula (I):
R.sup.1OR.sup.3(OR.sup.4).sub.nOR.sup.2 (I), in which R.sup.1 and R.sup.2, independently of one another, are a C1- to C4-alkyl group, R.sup.3 and R.sup.4, independently of one another, are an ethylene, propylene or butylene group, and n is an integer between 0 and 4.

3. The solution according to claim 1, wherein the cosolvent is a dialkylene glycol dialkyl ether of formula (I) or 1,2-propylene carbonate:
R.sup.1OR.sup.3(OR.sup.4).sub.nR.sup.2 (I), in which R.sup.1 and R.sup.2 independently of one another are a C1- to C4-alkyl group, R.sup.3 and R.sup.4 independently of one another are an ethylene, propylene or butylene group, and n is an integer between 0 and 4.

4. The solution according to claim 1, wherein the solvent is a solvent mixture comprising: 5 to 95% by weight of N-formylmorpholine, N-acetylmorpholine, or mixtures thereof, 5 to 95% by weight of the cosolvent, and 0 to 10% by weight of at least one further solvent.

5. The solution according to claim 1, which is a solution of the polyvinylidene fluoride or a copolymer comprising at least 70% by weight of the 1,1-difluoroethylene.

6. The solution according to claim 1, wherein the solution comprises 1 to 60% by weight of the polyvinylidene fluoride or the copolymer of 1,1-difluoroethylene, based on the total weight of the solution.

7. A coating or molding formed from the solution of claim 1.

8. A membrane, film or fiber formed from the solution of claim 1.

9. A coating on an electrode, wherein the coating is formed from the solution of claim 1.

10. A process, comprising: treating an object with a solvent to remove a residue or coating, comprising a polyvinylidene fluoride or a copolymer of 1,1-difluoroethylene, from the object, wherein the solvent comprises N-formylmorpholine, N-acetylmorpholine or mixtures thereof, and additionally a cosolvent selected from the group consisting of 1,2-propylene carbonate, a mono-alkylene glycol dialkyl ether, a di-alkylene glycol dialkyl ether, a polyalkylene glycol dialkyl ether, and mixtures thereof.

11. A solvent mixture, comprising: 5 to 95% by weight of N-formylmorpholine, N-acetylmorpholine, or mixtures thereof, 5 to 95% by weight of a cosolvent selected from the group consisting of a mono-alkylene glycol dialkyl ether, a di-alkylene glycol dialkyl ether, a polyalkylene glycol dialkyl ether, and mixtures thereof, and 0 to 10% by weight of at least one further solvent.

12. A solution of a polyvinylidene fluoride or a copolymer of 1,1-difluoroethylene, wherein the solution is formed from the solvent mixture of claim 11.

13. A method for producing a coating or a molding, the method comprising: introducing the solution of claim 1 into a hollow body of a desired mold, or onto a surface to be coated; and removing the solvent of the solution to obtain a coating or a molding.

14. A method for producing a coating on an electrode, the method comprising: introducing the solution of claim 1 onto a surface of an electrode to be coated; and removing the solvent of the solution to obtain a coating on an electrode.

15. A method for producing a solution, the method comprising: adding a polyvinylidene fluoride or a copolymer of 1,1-difluoroethylene to the solvent mixture of claim 11.

Description

EXAMPLES

Example 1

[0071] Polyvinylidene fluoride (PVDF; M.sub.w 180 000 g/mol, M.sub.n 71 000 g/mol) was dissolved in 150 g of solvent mixture consisting of 105 grams of NFM and 45 grams of Proglyme.

[0072] For this, the solvent mixture was heated to 100 to 120 C.

[0073] PVDF was then added to the solvent mixture stepwise in amounts of 7.5 grams and, after each step, stirred at 100 to 120 C. until everything had dissolved.

[0074] Overall, 52.5 grams of PVDF were thus completely dissolved in the solvent mixture. The solution therefore comprised 26% by weight of PVDF and was stable even after cooling to room temperature.

Example 2

[0075] Polyvinylidene fluoride (PVDF) was dissolved in 150 g of solvent mixture consisting of 105 grams of NFM and 45 grams of propylene carbonate.

[0076] For this, the solvent mixture was heated to 100 to 120 C.

[0077] Then, PVDF was added to the solvent mixture stepwise in amounts of 7.5 grams and, after each step, the mixture was stirred at 100 to 120 C. until everything had dissolved.

[0078] After the solution had reached a content of 15% by weight of PVDF, it was no longer possible to add further PVDF on account of the increase in viscosity in the apparatus used using a magnetic rod as stirrer. The resulting solution had a content of PVDF of 15% by weight. The PVDF had completely dissolved. The solution was stable ever after cooling to room temperature.

Comparative Example

[0079] The solvent used was only NFM. Firstly, 7.5 grams of PVDF were added as described above. This amount of PVDF could not be dissolved, or only scarcely dissolved, in pure NFM even upon heating to 100 to 120 C. Even heating to the boiling point of the solvent did not lead to a solution of the added PVDF.