JPH072815B2 - Method for producing perfluorinated copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a perfluorinated copolymer.

(Prior Art) Tetrafluoroethylene (hereinafter simply abbreviated as TFE) and perfluoroalkyl vinyl ether (hereinafter,
Abbreviated as PFAVE. ) And a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter, simply abbreviated as TFE-PFAVE copolymer).
Has properties such that it is superior in melt moldability while maintaining heat resistance and chemical resistance as compared with a TFE homopolymer. Therefore, the TFE-PFAVE copolymer is used in various fields as a lining in the chemical industry, a hose, a wire coating in the electric / electronic industry, and other molded products.

Currently, TFE-PFAVE copolymer is produced by
A method of simply copolymerizing with FAVE is known (Japanese Patent Publication 48).
-2223 publication).

(Problems to be Solved by the Invention) However, the above manufacturing method has the following problems.

First, PFAVE used as a raw material is generally produced by reacting a dimer of hexafluoropropylene oxide with an alkali metal salt and then thermally decomposing it. However, this synthesis of PFAVE has a large number of steps, and the total yield is low because some of these steps have low yields. This makes PFAVE expensive.

Further, since PFAVE has poor polymerizability, the utilization rate of PFAVE, that is, the ratio of PFAVE units bonded and present in the copolymer to the amount of PFAVE charged at the time of polymerization is extremely low. For example, according to the above Japanese Patent Publication No. 48-2223, PFAVE
The utilization rate is only a few percent to 30%. For this reason, a method or process for recovering expensive PFAVE is required.

In addition, the TFE-PFAVE copolymer obtained by the copolymerization of TFE and PFAVE contains a -COOH group,-, at the end of the molecular chain due to a polymerization initiator, a chain transfer agent, radical transfer on the growing chain, etc. CH
₂ OH group or -COF group is contained. These terminal groups are particularly thermally unstable and cause oxidation or thermal decomposition due to heat during molding, which causes generation of hydrogen fluoride. Further, it causes air bubbles to be mixed into the molded product. Therefore, there are problems that the molding machine is corroded and that the defective rate of the molded product due to the inclusion of air bubbles is high. In addition, molded articles of TFE-PFAVE copolymer are often used in semiconductor manufacturing processes that require high purity, but impurities such as trace amounts of hydrogen fluoride have become a problem in recent years. Deing of Anniversary Technical Meeting of Institut of Environmental Science (No.
32 times). 1986.397-405].

Thus, TFE-P obtained by the copolymerization of TFE and PFAVE
Although the FAVE copolymer originally has various excellent properties such as heat resistance, chemical resistance, and electrical properties,
It has many problems as mentioned above.

(Means for Solving the Problems) In view of the problems described above, the present inventors aim to more efficiently produce a TFE-PFAVE copolymer that can sufficiently exhibit the original excellent properties. I have been diligently researching.

That is, the object of the present invention is to obtain a copolymer having a predetermined ratio of TFE units and PFAVE units in the resulting copolymer by adjusting the molar ratio of two kinds of monomers to be used for the copolymerization to a predetermined ratio. It is to provide a manufacturing method.

Still another object of the present invention is, as compared with a TFE-PFAVE copolymer obtained by copolymerizing a TFE monomer and a PFAVE monomer, a TFE which is less likely to generate a corrosive gas generated by thermal decomposition of hydrogen fluoride gas or the like. -Providing a method for producing a PFAVE copolymer.

Further object of the present invention is TFE (I) monomers with the following general formula fluorinated alkyl vinyl ether monomers having the _{(II) CF 2 = CF-} O-CH 2 CnFlXmH (2 n + 1- l - m) (II) Another object of the present invention is to provide a method for producing a substantially perfluorinated copolymer by copolymerizing and, and then fluorinating the copolymer with molecular fluorine.

In general, direct fluorination of a polymer in which hydrogen is bonded to the main chain with a fluorine molecule can be performed by, for example, Journal of Polymer Science Part A-1 (J. Poly.Sc
i.Part A-1) The yield is poor as shown in the example of fluorination of polyvinyl fluoride shown in Volume 10, page 2129 (1972), and in some cases the physical properties of the fluorinated polymer deteriorate. Is known to do. However, the copolymer of the fluorine-containing alkyl vinyl ether having a special structure and TFE in the present invention can obtain a fluorinated product at a yield of almost 100%, and further has a heat resistance without impairing other properties by fluorination. Is significantly improved.

Further, CF ₂ = CF which is one of the monomers of (II) which is a fluorine-containing alkyl vinyl ether used in the present invention.
-OR (where R is an alkyl radical or a fluorinated alkyl radical) monomer polymer, or the monomer and TFE
Copolymers with are shown in British Patent No. 812,116. However, since the method described in this British patent is an emulsion polymerization method using water as a medium, each monomer unit composed of the monomer (I) and the monomer (II) in the copolymer is used as in the present invention. It is impossible to freely control a given ratio.

Moreover, the British patent does not teach at all to make perfluorinated copolymers. Furthermore, there is no mention in the specification of the British patent that, when the copolymer described therein is fluorinated, the heat resistance is improved without impairing various physical properties.

The present invention however, TFE (I) and the following general formula monomer represented by _{(II) CF 2 = CFOCH 2} CnFlXmH (2 n + 1- l - m) (II) Are used in the respective ranges of 99.5 to 50 mol% of the monomer of (I) and 0.5 to 50 mol% of the monomer of (II) and at a predetermined monomer ratio, and the monomers are dissolved in an organic solvent to carry out copolymerization. A perfluorinated copolymer having a predetermined monomer unit ratio, characterized in that the copolymer is made to have a monomer unit in substantially the same ratio as the monomer ratio, and then the copolymer is fluorinated with molecular fluorine. A method for producing a polymer is provided.

Further, in the present invention, a preferred embodiment is such that, at the start of the copolymerization reaction, the pressure of TFE (I) in the gas phase in the polymerization reactor is set to 1 kg.
/ cm ² in the range of G to 100 Kg / cm ² G is to carry out the polymerization in the predetermined pressure. In this case, controlling the ratio of the monomer unit of (I) and the monomer unit of (II) in the obtained perfluorinated copolymer to a predetermined ratio, that is, a copolymer of monomer units in almost the same ratio as the ratio of the monomer. Can be obtained.

In the present invention, the TFE (I) unit in the copolymer is 9
9.5-50mol%, Fluorine-containing alkyl vinyl ether (II)
It is preferable that the unit is 0.5 to 50 mol%. That is, a copolymer having a unit of (II) of 0.5 mol% or less is a perfluorinated copolymer having poor moldability, and a perfluorinated copolymer having a monomer of (II) of more than 50 mol% is difficult to be fluorinated. The physical properties of the copolymer obtained by the method are slightly deteriorated.

One of the monomers used in the copolymerization of the present invention is TFE, but another monomer, a fluorine-containing alkyl vinyl ether, can be adopted without any limitation as long as it is a monomer represented by the general formula (II). Specific examples of the monomer (II) that can be preferably used are CF ₂ = CFOCH ₃ , CF ₂ = CFOCH ₂ F, CF ₂ = CFOCH ₂ CF ₃ , CF ₂ = CFOCH ₂ CF ₂ H, CF ₂ = CFOCH. ₂ CF ₂ CF ₃ , CF ₂ = CFOCH ₂ CF ₂ CF ₂ H, CF ₂ = CFOCH ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFOCH ₂ CF ₂ CF ₂ CF ₂ H, CF ₂ = CFOCH ₂ CF ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFOCH ₂ CF ₂ CF ₂ CF ₂ CF ₂ H, CF ₂ = CFOCH ₂ CF ₂ CF ₂ Cl, CF ₂ = CFOCH ₂ CF ₂ CF ₂ Br, and the like. Above all, the polymerizability with TFE and T
For reasons such as easiness of fluorination of the copolymer with FE, n is preferably an integer of 0 to 10 and l is preferably an integer of 2n to 2n + 1. Further, the following formula CF ₂ = CFOCH ₂ (CF ₂ ) pY The compound represented by is particularly preferable.

The fluorine-containing alkyl vinyl ether which is the monomer (II) used in the present invention can be produced by a known method.

Next, the copolymerization method in the present invention can be adopted without any limitation as long as it is a polymerization means for dissolving the monomer (I) and the monomer (II) in an organic solvent. Further, in order to remove the heat of polymerization, it is possible to carry out the polymerization in a solution in which each monomer is dissolved in the presence of 0.3 to 10 times by weight, preferably 1 to 5 times by weight, of the organic solvent in the solution. Of course, since TFE, which is the monomer of (I), is a gas in many cases, it is preferable to pressurize and supply it to the gas phase part of the polymerization reactor during the polymerization.

The organic solvent used in the present invention is not particularly limited,
Generally, chlorofluorocarbons and perfluoro compounds are preferably used. For example, fluorinated solvents such as trichlorotrifluoroethane, dichlorotetrafluoroethane, trichlorofluoromethane, dichlorodifluoromethane, perfluorocyclohexane, perfluorocyclobutane, perfluorotributylamine, perfluorotriamylamine, perfluoropolyethers are preferable. . To specifically exemplify the polymerization method, a deoxygenated organic solvent and a fluorine-containing alkyl vinyl ether are added to a pressure vessel equipped with a stirrer and a thermometer. The ratio of addition of these is selected in such a range that the viscosity increases with the progress of the polymerization and the stirring becomes difficult, or the heat of the polymerization cannot be removed due to insufficient stirring and the polymerization is not easily maintained. . Usually, it is preferable to select the fluorine-containing alkyl vinyl ether in the range of 0.1 to 30 parts by weight, preferably 1 to 10 parts by weight with respect to 100 parts by weight of the organic solvent. Further, distilled water can be added.

Next, in order to deoxidize the inside of the reaction container, the operation of degassing after cooling and solidifying the contents of the reaction container is repeated. Then, TFE is added to the gas phase part of the reaction vessel. A radical generator as a polymerization initiator is dissolved in an organic solvent and added, and then TFE is pressurized to a predetermined pressure to carry out polymerization while maintaining the temperature at the polymerization temperature.

Although the polymerization time varies depending on the TFE pressure, the amount of the radical generator added, etc., a copolymer is sufficiently formed if it is several tens to several tens of hours.

Examples of the polymerization initiator used in this method include dialkyl peroxides, diacyl peroxides, peroxydicarbonates and azo-based ones. Considering the heat resistance of the copolymer generally obtained, a fluorine-containing, preferably perfluoro, radical generator is used. For example, a fluorine-containing diacyl peroxide represented by the following formula is preferably used.

Examples of the radical generator that can be preferably used in the present invention are as follows.

The amount of the above-mentioned radical generator to be used cannot be unconditionally determined depending on the solvent used, the polymerization conditions, especially the polymerization temperature, but is 0.5 to 20 mol%, preferably 1 to 10 mol, based on the fluorine-containing alkyl vinyl ether usually used in the polymerization. % Radical additive may be added at the time of charging or intermittently. Depending on the conditions, it may be difficult for the polymerization to proceed. In such a case, it is an effective means to add the radical generator again during the polymerization.

The pressure of TFE sufficiently polymerization reaction be in the range of ^{1Kg / cm 2 G~100Kg / cm 2} G proceeds, but the preferred pressure 1Kg / cm ² G~30
It is Kg / cm ² G. TFE is generally used when the TFE pressure is low.
A copolymer with a low content of
The content of TFE becomes high and the production rate of the copolymer becomes high. Of course, the polymerization will proceed even if the lower and upper limits of the pressure are exceeded, but if the pressure is too high, the disadvantage will be that the apparatus will be considerably expensive. The temperature at the time of polymerization is determined by using the decomposition rate of the radical generator used as one guide, but it is usually 0.
C. to 100.degree. C., preferably about 5.degree. C. to 80.degree. 5 ° C for fluorine-containing or perfluoro-diacyl peroxide, which has a large decomposition rate even at low temperatures.
It is preferably about -60 ° C. If necessary, an organic compound such as methanol, methyl ether, methane or ethane may be added as a chain transfer agent to control the molecular weight.

Furthermore, in order to modify the properties of the copolymer obtained,
Fluoroolefins such as hexafluoropropylene, chlorotrifluoroethylene, and vinylidene fluoride may be added to TFE. It is generally preferable to use 5 mol% or less of TFE.

The produced copolymer is recovered by separating the organic solvent (and water) from the polymerization mixture. In this case, water can be easily separated from the copolymer by filtration, but the organic solvent may not be recovered by filtration because the copolymer is dispersed in a high concentration. In such a case, the copolymer can be recovered by using a centrifuge or by drying the copolymer under reduced pressure. The fluorine-containing alkyl vinyl ether used in the present invention is well copolymerized with TFE, and the pressure during TFE polymerization is 1K.
If the amount is more than g / cm ² G, most of them are copolymerized in a short time and hardly detected in the organic solvent used for the polymerization. Therefore, the step of recovering the fluorine-containing alkyl vinyl ether is unnecessary. This is one of the great advantages of the copolymerization method of the present invention.

Next, the separated copolymer is dried and then fluorinated. As the fluorination method, a method conventionally used for fluorinating a solid phase or powdery substance can be adopted. For example, the above-mentioned Journal of Polymer Science Part A
-1 (J.Poly.Sci.PartA-1) Vol. 10, pp. 2129 (197)
The method described in 2) is an example.

In the present invention, fluorination with fluorine gas is preferably adopted. In the fluorination method using fluorine gas, the copolymer is suspended in a solvent such as carbon tetrachloride or chlorofluoroethane, which has low reactivity with fluorine, and then fluorine diluted with an inert gas is passed if necessary. There is a liquid phase method of fluorinating by such a method, or a so-called gas phase method of directly fluorinating a copolymer with fluorine diluted with an inert gas as necessary, but a gas phase method can be used because it is simple in terms of equipment. Method is preferred. In the case of the gas phase method, the copolymer is placed in a reaction vessel made of a material having corrosion resistance to fluorine gas, and the reaction temperature is room temperature to 200 ° C., preferably 50 to 100 ° C. under vibration and stirring to improve contact. At a temperature of 10 to 10 with an inert gas such as nitrogen or He
Fluorine gas diluted to about 100%, preferably about 50 to 100% is used to continuously or batchwise 1 to 20 kg / cm ²
Fluorination may be carried out under the pressure of G for several to 100 hours, preferably for 5 to 30 hours.

(Effect) According to the method of the present invention, since the fluorine-containing alkyl vinyl ether used as a raw material has a very good polymerizability, the copolymerization with TFE easily proceeds and the fluorine-containing alkyl vinyl charged in the reaction vessel is introduced. Most vinyl ethers are used for polymerization. Therefore, it is not necessary to recover the unreacted fluorine-containing alkyl vinyl ether after completion of the polymerization.

Furthermore, in the case of conventional TFE-PFAVE copolymerization, there is a large difference between the charged monomer composition and the composition in the copolymer obtained after polymerization, and it is difficult to control the composition in the copolymer, In the copolymerization of fluorinated alkyl vinyl ether and TFE, the composition of the copolymer is very easy to control because the monomer composition and the composition in the copolymer pair take close values.

Further, the perfluorinated copolymer obtained by the method of the present invention is TF obtained by the conventional copolymerization of TFE and PFAVE.
It does not have a labile group at the end of the molecular chain unlike E-PFAVE copolymer. Therefore, the perfluorinated copolymer obtained by the method of the present invention has an extremely small amount of hydrogen fluoride generated by heating. Of course, properties such as thermal stability and chemical resistance are
The excellent properties of the TFE-PFAVE copolymer are retained as they are.

Furthermore, since the fluorine-containing alkyl vinyl ether used as a raw material in the present invention is cheaper than PFAVE which is a raw material of a conventional TFE-PFAVE copolymer, the present invention is also excellent in terms of cost. be able to.

Example 1 1,1,2-Trichloro-1,2,2-trifluoroethane 1, CF ₂ = CFOCH ₂ CF ₂ CF ₃ 10 g, polymerized beforehand by distillation in a stainless steel autoclave 3 equipped with a stirrer, polymerization As an initiator, 1,1,2-trichloro-1,2,2-trifluoroethane 10 C.C. containing 1 g of CF ₃ CF ₂ CO _{2 2} was added. The autoclave was cooled with liquid oxygen and the contents were After solidifying
Degas with a vacuum pump. Further, nitrogen was introduced up to a pressure of 3 Kg / cm ² G, and the temperature was raised (−5 ° C.) while maintaining the pressure until the contents were dissolved. This operation was also repeated 3 times to remove oxygen in the autoclave. After cooling and solidifying again with liquid oxygen and degassing with a vacuum pump, the temperature was raised, and when it reached about 15 ° C, TFE was introduced at a pressure of 3 Kg / cm ² G to saturate and dissolve TFE, and then TFE was added. The inlet valve of was closed. The temperature of the autoclave was raised to 20 ° C to start the polymerization. When the polymerization was continued for 5 hours, the pressure in the autoclave dropped to about the vapor pressure of trichlorotrifluoroethane, so the polymerization was stopped. After that, the solvent and unpolymerized CF ₂ = C were added to the autoclave.
A vacuum pump was connected via a trap for cooling and collecting FOCH ₂ CF ₂ CF _3, and the pressure in the autoclave was reduced while stirring, and the solvent used and unpolymerized fluorine-containing alkyl vinyl ether were recovered in the trap. After completely removing the solvent, when the autoclave was opened, a white powdery copolymer was formed. When the obtained copolymer was dried under reduced pressure at 150 ° C. for 10 hours, about 150 g of the copolymer was obtained.

Moreover, when the collected solvent was analyzed by gas chromatography, unpolymerized CF ₂ = CFOCH ₂ CF ₂ CF ₃ was not detected, and the charged CF ₂ = CFOCH ₂ CF ₂ CF ₃ was converted at almost 100% conversion rate. It was found to be polymerized. The TFE conversion was calculated from the pressure change and was about 97%. 400 ° C by pyrolysis gas chromatography mass spectrometry (hereinafter abbreviated as Py-GC / MS)
As a result of analysis of decomposition products at
_{Since 3} CF ₂ CH and CF ₃ CF ₂ CH ₃ were detected, it was confirmed that the side chain structure was —OCH ₂ CF ₂ CF ₃ .

From this result and the IR measurement result, 3.1 mol% It was found that the monomer unit represented by the formula (3) was contained in the copolymer, and the composition at the time of charging was 3.0 mol%.

Further, in order to fluorinate the obtained copolymer, 35 g was charged into a stainless steel reactor having an inner volume of 140 C.C., which was rotatable by a motor. After degassing the inside of the reactor, fluorine having a concentration of about 100% by volume was introduced into the reactor up to 8 kg / cm ² G. The reactor was immersed in an oil bath at 85 ° C. and the fluorination reaction was carried out for 15 hours while stirring. Then, the gas inside was replaced with nitrogen, and the fluorinated copolymer was taken out and dried under reduced pressure in a drier at 150 ° C. for 20 hours to obtain approximately 35 g of a white copolymer. In addition, the obtained copolymer was analyzed by Fourier transform infrared absorption spectrum (hereinafter referred to as FT
-Abbreviated as IR. ), 2.9 mol% CH bond was not detected at all.

Examples 2 to 5 Using the polymerization apparatus and method of Example 1, fluorine-containing copolymers having different compositions were synthesized. Table 1 shows the conditions changed from Example 1, the monomer conversion rate, and the analytical values of the obtained copolymer.

Further, the obtained copolymer was fluorinated. Table 2 shows the fluorination conditions and the results.

Example 6 In a 300 ml autoclave, CF ₂ = CFOCH ₂ (CF ₂ ) ₂ CF ₃ 4.1 g, and 1,1,2-
The same deoxidation operation as in Example 1 was performed by adding 150 ml of trichloro-1,2,2-trifluoroethane. After that, TFE is 6 kg / c
It was introduced at a pressure of m ² G and the TFE feed valve was closed after TFE was saturated and dissolved. After setting the autoclave temperature to 20 ° C,
As a polymerization initiator, 5 ml of a trichlorotrifluoroethane solution containing 0.15 g of (CF ₃ CF ₂ .CO _{2 2} was injected under pressure.

When the polymerization was continued for 5 hours, the pressure inside the autoclave dropped to about the vapor pressure of the solvent. When the solvent was distilled off under reduced pressure according to the procedure of Example 1, a white powdery copolymer was obtained.

Analysis of the recovered solvent by gas chromatography
CF ₂ ＝ CFOCH ₂ (CF ₂ ) ₂・ CF ₃ was hardly detected and almost 1
The conversion rate was 00%. Also, TFE is almost 100% due to pressure change.
It was found that the conversion rate was.

On the other hand, when the obtained copolymer was dried under reduced pressure at 150 ° C. for 10 hours and analyzed by Py-GC / MS and IR, it was found to be 1.4 mol%. It contained the monomer unit represented by, and was in agreement with the monomer composition of 1.45 mol% at the time of charging.

30g of the obtained copolymer was coated with a heater around the inner diameter 1
It was filled in a cm stainless steel tube. Nitrogen was introduced from the lower end of the tube and discharged from the other end, and the inside of the tube was replaced with nitrogen. After the replacement, fluorine diluted to 50% by volume with nitrogen was introduced from the lower end of the tube at a flow rate of 10 C.C./min and discharged from the other end. The temperature of the heater was raised to 85 ° C. and the reaction was continued for 20 hours. After the reaction, about 30 g of the fluorinated copolymer was recovered, and the amount of 1.3 mol% was analyzed by IR analysis. Of monomer units were included. In addition, absorption due to CH bond could not be detected.

Example 7 In a 300 ml autoclave, CF ₂ = CFOCH ₂ CF ₂ CF ₂ Cl 1.6 g, 1,1,2-trichloro-1,2,2-trifluoroethane 150 ml as a solvent, and (CF ₃ CF ₂ · CO _{2 2} 0.5 g was added, which resulted in the removal of oxygen by the operation used in example 1, 3.0 Kg of TFE
/ cm ² G, and after saturated dissolution, stop the supply of TFE
Polymerization was carried out at 20 ° C. for 5 hours.

The obtained white powder copolymer was 2.7 mol% by Py-GC / MS and IR analysis. It was found to contain a monomer unit represented by. This almost matched the monomer composition at the time of charging.

Further, when the conversion of the monomer was measured, it was about 98% for both TFE and fluorine-containing alkyl vinyl ether.

Copolymer powder (15 g) and perfluorotributylamine (300 g) were added to a stainless steel 500 C.C. reactor having a stirrer and a refluxer for fluorinating the obtained copolymer.
After substituting the inside of the reactor with nitrogen, fluorine diluted to 80% with helium was introduced at 10 C.C./min and discharged through a reflux condenser. The temperature in the reactor was set to 150 ° C. and the reaction was continued while introducing fluorine for 15 hours. After the reaction, the powder was collected by filtration, washed with trichlorotrifluoroethane, and dried under reduced pressure at 150 ° C for 15 hours. Weight after drying is 14.5g, IR analysis and P
When y-GC / MS analysis was performed It was found that it contained 2.5 mol% of the monomer unit represented by, and did not contain CH bond and CCl bond.

Example 8 Polymerization was performed in the same manner as in Example 1 except that 7.8 g of CF ₂ = CFOCH ₂ CF ₃ was used. When the polymerization was carried out for 4 hours, the polymerization was almost completed. When the conversion rates of the fluorine-containing alkyl vinyl ether and TFE were determined in the same manner as in Example 1, both were found to be approximately 9
It was 8%. When the obtained copolymer was dried under reduced pressure, it was about 145 g.

The obtained copolymer was analyzed and found to be 3.0 mol% It contained the monomer unit of, and was almost in agreement with the charged composition.

In order to further fluorinate the obtained copolymer, 10 g was charged into the stainless steel reactor used in Example 1, and fluorine gas diluted to 75% with helium was sealed at 5 Kg / cm ² G at 85 ° C.
Fluorination was carried out for 20 hours. After fluorination, about 10 g of fluorinated copolymer was obtained, and the analysis showed that it was about 2.6 mol%.
of It had a monomer unit of, and no CH bond could be detected.

Comparative Example 1 Distilled water 150 ml, C in a 500 ml autoclave equipped with a stirrer
F ₂ = CFOCH ₂ CF ₂ CF ₃ 4.2 g, as polymerization initiator (NH ₄ ) ₂ S ₂ O
₈ 0.26g, 0.1g of ammonium salt of perfluorooctanoic acid as an emulsifier was added, deoxidized by the procedure of Example 1, and then 70 ° C.
The TFE pressure was applied at a constant pressure of 3 Kg / cm ² G and polymerization was carried out for about 2 hours, but there was almost no decrease in pressure.
The pressure of E was 6 kg / cm ² G, and the polymerization was carried out at a constant pressure for 8 hours. When the pressure of TFE was released from the autoclave and the autoclave was opened, a white opaque liquid in which the copolymer was dispersed was obtained.After filtration, it was dried under reduced pressure at 150 ° C. for 10 hours to obtain 66 g of a white powdery copolymer. Was obtained. Py-GC / MS and
When analyzed by IR, 2.0 mol% The monomer unit represented by From this result, the conversion of the fluorinated alkyl vinyl ether was calculated to be about 70%. That is, the copolymerizability of TFE is poor, and the proportion of charged monomers does not match the proportion of monomer units in the resulting copolymer.

Further, the obtained copolymer was fluorinated using the method, conditions and apparatus of Example 1, and as a result, 1.6 mol% of monomer units was obtained. And a copolymer containing almost no CH bond was obtained.

Example 9 The copolymers obtained in Examples 1 to 8 and Comparative Example 1 before fluorination and after fluorination were subjected to thermal analysis.
Table 3 shows the thermal decomposition temperature of each copolymer. Further, the copolymer before fluorination and the copolymer after fluorination obtained in Examples 1 to 8 and Comparative Example 1 were applied with a load of 50 Kg / cm ² at 370 ° C. using a Koka type flow tester. , 0.5mmφ × 5m
The melt viscosity when extruded from a m die was determined. The results are shown in Table 3. Furthermore, Examples 1 to 8 and Comparative Example 1
The fluorinated copolymer and the fluorinated copolymer obtained in 1. were pressed at a temperature of 350 ° C. to prepare a sheet having a thickness of 1 to 2 mm, and then the yield strength was determined according to JIS-K7113. , Tensile strength and elongation were measured. The results are also shown in Table 3.

Further, the pre-fluorination copolymer and the post-fluorination copolymer obtained in Examples 1 to 8 and Comparative Example 1 were pressed at a temperature of 350 ° C., and the chemical resistance of the sheet having a thickness of 1 to 2 mm was prepared. The results are shown in Table 4.

Example 10 In order to obtain a copolymer composition curve, tetrafluoroethylene was copolymerized with 2,2,3,3,3-pentafluoropropyltrifluorovinyl ether. Freon 113 was used as a solvent and a polymerization initiator (C ₂ F ₅ · COO ₂ was used. Polymerization initiator concentration of 0.3 to 1 mol% (based on all monomers), tetrafluoroethylene pressure of 1 to 3 Kg / cm ² G , Polymerization temperature 20
Polymerization experiments were carried out at 5 ° C and a monomer conversion rate of 5 to 20 mol%. The copolymer composition curve was determined according to the Fineman-Ross method. The obtained results are shown in FIG. For comparison, the copolymer composition curve of perfluoropropyl vinyl ether and tetrafluoroethylene is shown in “Zurnal Plyclad Hemiya, 1984, 57 (5), 1126.
It was calculated using the copolymerizability ratio described in "-8". The results are shown in FIG.

Comparative Example 2 Example 1 except that 5.0 g of perfluoropropyl vinyl ether was used instead of the fluorine-containing alkyl vinyl ether.
The same copolymerization was repeated.

TFE was introduced at 3.0 kg / cm ² G and reacted at 25 ° C. for 110 minutes.

Only 1.5 g of the copolymer was obtained, and analysis of the solvent revealed that perfluoropropyl vinyl ether showed almost no fluorocarbons.
It remained inside.

FT-IR analysis showed that the above copolymer contained 2.9 mol% perfluoropropyl vinyl ether. The melting point by differential thermal analysis is 308-332 ° C, which is about 430 from the thermobalance.
It was confirmed to decompose at ℃.

[Brief description of drawings]

FIG. 1 is a copolymerization composition curve in the copolymerization of 2,2,3,3,3-pentafluoropropyltrifluorovinyl ether and tetrafluoroethylene. FIG. 2 is a copolymerization composition curve of perfluoropropyl vinyl ether and tetrafluoroethylene.

Claims (1)

[Claims] 1. A monomer represented tetrafluoroethylene (I) by the following general formula _{(II) CF 2 = CFOCH 2} CnFlXmH (2 n + 1- l - m) (II) Are used in the respective ranges of 99.5 to 50 mol% of the monomer of (I) and 0.5 to 50 mol% of the monomer of (II) and at a predetermined monomer ratio, and the monomers are dissolved in an organic solvent to carry out copolymerization. A perfluorinated copolymer having a predetermined monomer unit ratio, characterized in that the copolymer is made to have a monomer unit in substantially the same ratio as the monomer ratio, and then the copolymer is fluorinated with molecular fluorine. Method for producing polymer.