Perfluorovinyloxy polyether carboxylic acid alkali metal salt and method for producing the same

Abstract

A perfluorovinyloxy polyether carboxylic acid alkali metal salt represented by the general formula is provided:
CF.sub.2═CF[OCF.sub.2CF(CF.sub.3)].sub.bO(CF.sub.2).sub.aO[CF(CF.sub.3)CF.sub.2O].sub.cCF(CF.sub.3)COOM  [I],
wherein M is alkali metal, preferably sodium or potassium, a is an integer of 1 to 6, preferably 2, and b+c is an integer of 0 to 6, preferably 0 or 1. This perfluorovinyloxy polyether carboxylic acid alkali metal salt is produced by subjecting a perfluorovinyloxy polyether carboxylic acid alkyl ester represented by the general formula:
CF.sub.2═CF[OCF.sub.2CF(CF.sub.3)].sub.bO(CF.sub.2).sub.aO[CF(CF.sub.3)CF.sub.2O].sub.cCF(CF.sub.3)COOR  [II],
wherein R is an alkyl group having 1 to 12 carbon atoms, a is an integer of 1 to 6, and b+c is an integer of 0 to 6; to hydrolysis or solvolysis in the presence of an alkali metal hydroxide.

Claims

1. A perfluorovinyloxy polyether carboxylic acid alkali metal salt of the general formula:
CF.sub.2═CF[OCF.sub.2CF(CF.sub.3)].sub.bO(CF.sub.2).sub.aO[CF(CF.sub.3)CF.sub.2O].sub.cCF(CF.sub.3)COOM  [I] wherein M is alkali metal, a is an integer of 1 to 6, and b+c is an integer of 0 to 6.

2. The perfluorovinyloxy polyether carboxylic acid alkali metal salt according to claim 1, wherein the alkali metal is sodium or potassium, a is 2, and b+c is 0 or 1.

3. A method for producing a perfluorovinyloxy polyether carboxylic acid alkali metal salt of the general formula:
CF.sub.2═CF[OCF.sub.2CF(CF.sub.3)].sub.bO(CF.sub.2).sub.aO[CF(CF.sub.3)CF.sub.2O].sub.cCF(CF.sub.3)COOM  [I] wherein M is alkali metal, a is an integer of 1 to 6, and b+c is an integer of 0 to 6; the method comprising subjecting a perfluorovinyloxy polyether carboxylic acid alkyl ester of the general formula:
CF.sub.2═CF[OCF.sub.2CF(CF.sub.3)].sub.bO(CF.sub.2).sub.aO[CF(CF.sub.3)CF.sub.2O].sub.cCF(CF.sub.3)COOR  [II] wherein R is an alkyl group having 1 to 12 carbon atoms, a is an integer of 1 to 6, and b+c is an integer of 0 to 6; to hydrolysis or solvolysis in the presence of an alkali metal hydroxide.

4. The method for producing a perfluorovinyloxy polyether carboxylic acid alkali metal salt according to claim 3, wherein the molar ratio of the alkali metal hydroxide to the perfluorovinyloxy polyether carboxylic acid alkyl ester is from 0.95:1 to 1.05:1.

5. The method for producing a perfluorovinyloxy polyether carboxylic acid alkali metal salt according to claim 3, wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.

6. The method for producing a perfluorovinyloxy polyether carboxylic acid alkali metal salt according to claim 3, wherein the solvent used for the solvolysis is an aliphatic alcohol having 1 to 6 carbon atoms.

7. The method for producing a perfluorovinyloxy polyether carboxylic acid alkali metal salt according to claim 3, wherein the hydrolysis or solvolysis is performed by adding dropwise an aqueous solution or alcohol solution of the alkali metal hydroxide into an aqueous emulsion or alcohol solution of the perfluorovinyloxy polyether carboxylic acid alkyl ester.

Description

EXAMPLE 1

(1) Methyl 2,3,3,3-tetrafluoro-2-[1,1,2,2-tetrafluoro-2-(1,2,2-trifluorovinyloxy)-ethoxy]propanoate of the formula:
CF.sub.2═CFO(CF.sub.2).sub.2OCF(CF.sub.3)COOCH.sub.3 (a=2, b=0, c=0)
were prepared by a standard method. An ethanol solution (5 ml) of 5.19 g (13.3 mmol) of the above component was cooled to −10° C. or less using ice and salt. Subsequently, an ethanol solution (concentration: 15.8 wt. %) prepared by dissolving potassium hydroxide (purity: 85 wt. %; 0.9 g) in 5 ml of cooled ethanol was slowly added dropwise so that the temperature did not exceed −10° C. Eight hours later, the ethanol was removed by an evaporator. As a result, 4.90 g of wax-like white solid was obtained.

(2) The .sup.1H-NMR measurement results showed that the signal indicating methyl ester disappeared. In the .sup.19F-NMR measurement, the methine signal of —CF(CF.sub.3)— shifted. Therefore, it was concluded that potassium 2,3,3,3-tetrafluoro-2-[1,1,2,2-tetrafluoro-2-(1,2,2-trifluorovinyloxy)ethoxy]propanoate was obtained.

(3) .sup.19F-NMR (CFCl.sub.3, CD.sub.3OD solvent): δ(ppm): −134.75, −134.11 (m, 1F, F.sub.2C═CF—) −124.53, −124.44 (m, 1F, —CFCF.sub.3—) −121.82, −121.08 (m, 1F, E-FC═CF—) −114.31, −113.77 (m, 1F, Z—FC═CF—) −89.28 (s, 2F, ═CFOCF.sub.2—) −87.08, −83.74 (dd, 2F, —CF.sub.2OCFCF.sub.3—) −81.22 (s, 3F, —CFCF.sub.3—)

EXAMPLE 2

(4) Methyl 2,3,3,3-tetrafluoro-2-{1,1,2,3,3,3-hexafluoro-2-[1,1,2,2-tetrafluoro-2-(trifluorovinyloxy)ethoxy]propoxy}propanoate of the formula:
CF.sub.2═CFO(CF.sub.2).sub.2OCF(CF.sub.3)CF.sub.2OCF(CF.sub.3)COOCH.sub.3 (a=2, b=0, c=1)
and methyl 2,3,3,3-tetrafluoro-2-{1,1,2,2-tetrafluoro-2-[1,2,2,3,3,3-hexafluoro-2-(trifluorovinyloxy)propoxy]ethoxy}propanoate of the formula:
CF.sub.2═CFOCF.sub.2CF(CF.sub.3)O(CF.sub.2).sub.2OCF(CF.sub.3)COOCH.sub.3 (a=2, b=1, c=0)
were prepared by a standard method. An ethanol solution (8 ml) of 10.8 g (20.0 mmol) of a mixture of the above components was cooled to −10° C. or less using ice and salt. Subsequently, an ethanol solution (concentration: 12.5 wt. %) prepared by dissolving potassium hydroxide (purity: 85 wt. %; 1.32 g) in 10 ml of cooled ethanol was slowly added dropwise so that the temperature did not exceed −10° C. Eight hours later, the ethanol was removed by an evaporator. As a result, 9.88 g of wax-like white solid was obtained.

(5) The .sup.1H-NMR measurement results showed that the signal indicating methyl ester disappeared. In the .sup.19F-NMR measurement, the methine signal of —CF(CF.sub.3)— shifted. Therefore, it was concluded that a mixture of potassium 2,3,3,3-tetrafluoro-2-{1,1,2,3,3,3-hexafluoro-2-[1,1,2,2-tetrafluoro-2-(trifluorovinyloxy)ethoxy]propoxy}-propanoate and potassium 2,3,3,3-tetrafluoro-2-{1,1,2,2-tetrafluoro-2-[1,2,2,3,3,3-hexafluoro-2-(trifluorovinyloxy)propoxy]ethoxy}propanoate was obtained.

(6) .sup.19F-NMR (CFCl.sub.3, CD.sub.3OD solvent): δ(ppm): −144.12, −143.64 (m, 1F, OCF.sub.2CFCF.sub.3O—) −134.75, −134.11 (m, 1F, F.sub.2C═CF—) −124.53, −124.44 (m, 1F, —CFCF.sub.3—) −121.82, −121.08 (m, 1F, E-FC═CF—) −114.31, −113.77 (m, 1F, Z—FC═CF—) −89.30, −88.99 (m, 2F, ═CFOCF.sub.2—) −86.02, −83.21 (m, 4F, —CF.sub.2OCFCF.sub.3—) −81.06 (s, 3F, —CFCF.sub.3CO.sub.2—) −78.90 (s, 3F, —OCF.sub.2CFCF.sub.3—)

REFERENCE EXAMPLE

(7) The following components were charged in a stainless steel pressure vessel (internal volume: 10 L) equipped with a stirring blade.

(8) TABLE-US-00001 CF.sub.3CF.sub.2CF.sub.2[OCF(CF.sub.3)CF.sub.2]OCF(CF).sub.3COONH.sub.4 [emulsifier] 34 g CF.sub.2═CFO(CF.sub.2).sub.2OCF(CF.sub.3)COOK [reactive emulsifier] 2.4 g  Na.sub.2HPO.sub.4•12H.sub.2O [buffer] 17 g I(CF.sub.2).sub.4I [chain transfer agent] 27 g Ion exchange water 5,600 g  
Then, the inside of the vessel was replaced with nitrogen to remove oxygen from the vessel. Further, the following components were charged in the vessel.

(9) TABLE-US-00002 Perfluoro(methyl vinyl ether) CF.sub.2═CFOCF.sub.3 [PMVE] 790 g Vinylidene fluoride [VdF]/tetrafluoroethylene [TFE] 670 g mixed gas (VdF/TFE = 87.5 mol %/12.5 mol %)
The temperature in the vessel was raised to 50° C. When the temperature reached 50° C., the pressure of the vessel was 3.07 MPa.Math.G. After it was confirmed that the temperature was stabilized, 0.8 g of ammonium persulfate and 0.2 g of sodium bisulfite were added as an aqueous solution, and the polymerization reaction was initiated.

(10) After the polymerization reaction proceeded, and when the pressure in the vessel reached 3.00 MPa.Math.G, a monomer mixture having a mixing ratio of VdF/TFE/PMVE=79.6/11.4/9.0 mol % was introduced to raise the pressure to 3.10 MPa.Math.G. The pressure in the vessel was maintained at 3.00 to 3.10 MPa.Math.G during the polymerization reaction by introducing the gases having the above composition.

(11) When the total amount of the introduced gas reached 1,410 g, the addition of the gases was stopped. When the pressure was reduced to 0.20 MPa.Math.G, the vessel was cooled to terminate the polymerization reaction. It took 288 minutes from the supply of the initiator to the end of the polymerization. After completion of the reaction, 8,550 g of fluorine-containing elastomer latex was obtained as a reaction mixture.

(12) The obtained fluorine-containing elastomer latex was put in the same amount of 1 wt. % calcium chloride aqueous solution to coagulate the latex. Then, the coagulated latex was filtered, washed five times with a 5-fold amount of ion exchange water, and dried by a vacuum dryer, thereby obtaining 2,500 g of VdF/TFE/PMVE copolymer. It was confirmed from the .sup.19F-NMR measurement results that the obtained copolymer had the following composition:

(13) TABLE-US-00003 VdF 73.6 mol % TFE  9.5 mol % PMVE 16.9 mol % CF.sub.2═CFO(CF.sub.2).sub.2OCF(CF.sub.3)COOK 0.03 mol %

(14) The obtained copolymer (100 parts by weight) was compounded with the following components:

(15) TABLE-US-00004 MT carbon black  37 parts by weight Triallyl isocyanurate (TAIC WH60, produced by   4 parts by weight Nippon Kasei Chemical Co., Ltd.) Organic peroxide (Perhexa 25B-40, produced by 1.5 parts by weight NOF Corporation)
The mixture was kneaded using an open roll to prepare an unvulcanized compound, followed by press vulcanization at 180° C. for 6 minutes and oven vulcanization at 230° C. for 22 hours. The normal state physical properties (according to JIS K6253 corresponding to ISO 48, and JIS K6251 corresponding to ISO 37) and compression set (according to JIS K6262 corresponding to ISO 815) of the obtained vulcanizate were measured.

(16) Further, the unvulcanized compound before press vulcanization was bonded to a zinc phosphate-treated SPCC steel plate, and press crosslinking was performed at 180° C. for 6 minutes, thereby producing a fluorine-containing elastomer laminated metal plate. The fluorine-containing elastomer laminated metal plate was subjected to a 90 degree peel test (according to JIS K6256 corresponding ISO 813).

Comparative Reference Example 1

(17) In the Reference Example, a VdF/TFE/PMVE copolymer was obtained without using CF.sub.2═CFO(CF.sub.2).sub.2OCF(CF.sub.3)COOK among the emulsifier components.

(18) The following table shows the results obtained in the above Reference Example and Comparative Reference Example 1.

(19) TABLE-US-00005 TABLE Measurement items Ref. Ex. Comp. Ref. Ex. 1 Normal state physical properties Hardness (Duro A) 75 75 100% modulus (MPa) 5.5 5.7 Breaking strength (MPa) 19.9 18.8 Elongation at break (%) 250 240 Compression set (using a 3.5-mm diameter O ring) 200° C., 22 hr. (%) 26 25 200° C., 70 hr. (%) 32 34 90 degree peel test Peel strength (N/mm) 4.1 0.2

Comparative Reference Example 2

(20) The surface of a zinc phosphate-treated SPCC steel plate was coated with a solution prepared by dissolving an adhesive comprising aminosilane and vinylsilane as main components (Chemlok AP-133, produced by Lord Corporation) in a 4-fold amount of methyl ethyl ketone. The resultant was dried at room temperature for 30 minutes, followed by baking at 150° C. for 30 minutes. The unvulcanized compound before press vulcanization prepared in Comparative Reference Example 1 was bonded to the adhesive layer-formed metal plate, and press crosslinking was performed at 180° C. for 6 minutes, thereby producing a fluorine-containing elastomer laminated metal plate. The fluorine-containing elastomer laminated metal plate was subjected to a 90 degree peel test in the same manner as mentioned above. As a result, the peel strength was 1.1 (N/mm).

INDUSTRIAL APPLICABILITY

(21) Due to the high polymerization ability, the perfluorovinyloxy polyether carboxylic acid alkali metal salt of the present invention can be effectively used as a crosslinking agent or modifier for various polymers. Further, due to the high fluorine content, various polymers using this metal salt not only have enhanced or improved heat resistance, weather resistance, chemical resistance, and other properties, but also exhibit a low refractive index. Therefore, the perfluorovinyloxy polyether carboxylic acid alkali metal salt of the present invention can also be applied to anti-reflective films for displays, clad materials of optical fibers, etc.

(22) Furthermore, since the terminal carbonyl group is a polar functional group, when the perfluorovinyloxy polyether carboxylic acid alkali metal salt of the present invention is used for adhesive applications, the adhesion to various members can be improved. In addition, due to the surface active properties, the perfluorovinyloxy polyether carboxylic acid alkali metal salt of the present invention can also be used for applications such as various mold release coating agents, surface coating agents, surface modifiers, and water- and oil-repellents.