JPH072816B2 - Fluorine-containing random copolymer and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel fluorine-containing random copolymer and a method for producing the same.

(Prior Art and Problems to be Solved by the Invention) Conventionally, tetrafluoroethylene (hereinafter simply abbreviated as TFE) and par are used as fluorine-containing resins having excellent chemical resistance, heat resistance, melt moldability, and electrical characteristics. A copolymer of fluoropropyl vinyl ether (hereinafter abbreviated as PPVE) (hereinafter abbreviated as PFA) has been produced and is used in a wide range of industrial fields due to its excellent properties.

However, the copolymer has the following problems. First, PPVE, which is a comonomer, is currently manufactured by reacting a dimer of hexafluoropropene oxide with an alkali metal salt and then thermally decomposing it, but since there are many manufacturing processes and there are also processes with low yield, The overall yield of PPVE is low. Furthermore, since PPVE has poor polymerizability with TFE, the utilization rate of PPVE, that is, the proportion of PPVE charged at the time of polymerization is extremely low. For example, according to JP-B-48-2223, the utilization rate of PPVE is only a few to 30%. Therefore, a method and process for recovering expensive PPVE is required. Further, there is a loss of PPVE in this step, which makes the copolymer expensive.

On the other hand, British Patent No. 812116 discloses a homopolymer of a monomer represented by CF ₂ = CF-OR (where R is an alkyl radical or a fluorinated alkyl radical) and a copolymer with TFE. There is. However, the method for copolymerizing CF ₂ ═CF-OR and TFE described in this British patent is
This is an emulsion polymerization method using water as a medium. According to the confirmation by the inventors, when the copolymerization of CF ₂ ═CF-OR and TFE is carried out by emulsion polymerization, the obtained copolymer is CF ₂ ═CF-OR
It has the same melting point (327 ° C) as the homopolymer of TFE even though about 6 mol% of the monomer unit based on is introduced, and the tensile strength of the sheet obtained from this copolymer is 200 kg. It was as low as / cm ² .

Therefore, an object of the present invention is to provide a novel fluorocopolymer having a high monomer utilization rate and having features such as chemical resistance, mechanical strength, and heat resistance.

(Means for Solving the Problems) In view of the above problems, the present inventors have good copolymerizability in a wide composition with fluorine-containing olefin, particularly TFE,
In addition, many compounds were synthesized in order to search for fluorine-containing vinyl ether compounds with high utilization rates, and copolymerization experiments were repeated.
It has been found that it has a good copolymerizability with E and that most fluorine-containing vinyl ethers are copolymerized in a short time and once. The inventors have found that the copolymer obtained by solution polymerization has excellent chemical resistance, mechanical strength and heat resistance, and also has excellent melt moldability, and has completed the present invention.

That is, the present invention includes (1) (A) a monomer unit represented by the general formula [I] CF ₂ CF ₂ [I] 90 to 99.5 mol%, and (B) a general formula [II] The melt viscosity measured at 350 ° C. is 10 ² to 10 ⁷ poise and the melting point is 290
To 325 ° C., and (2) (A) a monomer unit represented by the general formula [I] CF ₂ CF ₂ [I] 60 mol% or more Less than 90 mol% and (B) general formula [II] It is characterized by having a monomer unit of 10 mol% or more and 40 mol% or less, a melt viscosity measured at 200 ° C. of 10 ² to 10 ⁷ poise, and a glass transition temperature of −10 ° C. or less. It is a fluorine-containing random copolymer.

In the monomer unit represented by the general formula [II], X may be a hydrogen atom or a halogen atom, and each halogen atom of fluorine, chlorine, bromine and iodine is adopted. Further, n may be an integer of 1 or more, but for the reason that the fluorine-containing random copolymer of the present invention is easy to produce, that is, the ease of polymerization, n is 1 to 12, more preferably 1 to It is preferably in the range of 8.

The composition of each monomer unit represented by the above general formulas [I] and [II] is 60 to 60% by weight of the monomer unit represented by the above general formula [I].
It is 99.5 mol%, but preferably 70 to 99 in order to improve the melt moldability of the obtained fluorine-containing random copolymer.
The monomer unit represented by the general formula [II] is 0.5 to 40 mol%, preferably 1 to 30 mol%. When the monomer unit represented by the general formula [II] is less than 0.5 mol%, the melt moldability is poor, while when it exceeds 40 mol%, a solid copolymer cannot be obtained and is in an oily state. Is not preferable.

In the fluorine-containing random copolymer of the present invention, the monomer units represented by the above general formulas [I] and [II] are randomly arranged.

Since the fluorine-containing random copolymer of the present invention is insoluble in various solvents, the molecular weight cannot be determined by ordinary means. However, since the melt viscosity of the fluorine-containing random copolymer of the present invention depends on the content and molecular weight of the monomer unit represented by the general formula [II], the molecular weight can be estimated by the melt viscosity.

The melt viscosity of the fluorine-containing random copolymer of the present invention varies depending on the composition of each monomer unit represented by the general formulas [I] and [II]. For example, when the monomer unit represented by the general formula [II] is in the range of 0.5 mol% or more and 10 mol% or less, the melt viscosity measured at 350 ° C. is in the range of 10 ² to 10 ⁷ poise, and Over 40 mol% of monomer unit exceeds 10 mol%
In the following range, the melt viscosity measured at 200 ° C is 10 ²
It will be in the range of ~ 10 ⁷ poise.

Further, the fluorine-containing random copolymer of the present invention, the monomer unit represented by the general formula [II] is 0.5 mol% or more 10 mol%
Those having the following ranges have melting points of 290 to 325 ° C, preferably 29
It is in the range of 0 to 320 ° C. Since the melting point of the copolymer obtained by emulsion polymerization is 327 ° C., the fluorine-containing random copolymer of the present invention is clearly distinguished from the copolymer obtained by emulsion polymerization. The thermal decomposition temperature of the fluorine-containing random copolymer of the present invention having the above composition is in the range of 370 to 410 ° C.

The monomer unit represented by the general formula [II] exceeds 10 mol% and 40
Those having a mol% or less range do not show a clear melting point, but have a glass transition temperature of -10 ° C or lower, generally in the range of -10 to -100 ° C, and the glass transition of the copolymer obtained by emulsion polymerization. The temperature is much lower than 130 ℃. Further, the fluorine-containing random copolymer of the present invention having the above composition has a good transmittance of visible to ultraviolet light and generally has an absorbance of light of 250 mm of 0.4 or less.

The fluorine-containing random copolymer of the present invention has an infrared absorption spectrum (hereinafter referred to as IR) in the vicinity of 2990 cm ^-1 .
CH ₂ - group, 900 cm -CH ₂ OCF ₂ around ^-1 - group, and -CF ₂ near 1200 cm ^-1 - has an absorption band based on the group, check the absorption band of this such, quantifying Thus, the content of the monomer unit based on the fluorine-containing random copolymer of the present invention and the fluorine-containing vinyl ether represented by the general formula [II] can be determined.

FIG. 3 shows the IR of the film (thickness 50 μm) of the fluorine-containing random copolymer obtained in Example 1.

In addition, the structure of the side chain can be confirmed from the fragment generated by the decomposition of the side chain by thermal decomposition gas chromatography mass spectrometry (hereinafter referred to as Py-GC / MS). For example, with respect to the fluorine-containing random copolymer obtained in Example 1, a fragment resulting from a pentafluoropropyl group can be detected from Py-GC / MS.

The fluorine-containing random copolymer of the present invention may be produced by any method, but is particularly suitably produced by the method described below.

That is, tetrafluoroethylene and the general formula [III] CF ₂ ═CFOCH ₂ (CF ₂ ) nX [III] [wherein X is a hydrogen atom or a halogen atom, and n is 1
It is an integer above the above. ] A fluorine-containing vinyl ether represented by the following is dissolved in an organic solvent and copolymerized in the presence of a radical polymerization initiator.

Specific examples of the fluorine-containing vinyl ether represented by the above general formula [III] used in the present invention are as follows.

CF ₂ = CFOCH ₂ CF ₃ , CF ₂ = CFOCH ₂ CF ₂ CF ₃ , CF ₂ = CFOCH ₂ CF ₂ CF ₂ H, CF ₂ = CFOCH ₂ (CF ₂ ) ₂ CF ₃ , CF ₂ = CFOCH ₂ (CF ₂ ) ₃ CF ₃ , CF ₂ = CFOCH ₂ (CF ₂ ) ₄ CF ₃ , CF ₂ = CFOCH ₂ (CF ₂ ) ₅ CF ₃ , CF ₂ = CFOCH ₂ (CF ₂ ) ₆ CF ₃ , CF ₂ = CFOCH ₂ ( CF ₂ ) ₇ CF ₃ , CF ₂ = CFOCH ₂ CF ₂ Cl, CF ₂ = CFOCH ₂ CF ₂ Br, CF ₂ = CFOCH ₂ CF ₂ CF ₂ Br, CF ₂ = CFOCH ₂ CF ₂ CF ₂ Cl, CF ₂ = CFOCH ₂ (CF ₂ ) ₂ CF ₂ Br, CF ₂ = CFOCH ₂ (CF ₂ ) ₂ CF ₂ Cl, CF ₂ = CFOCH ₂ (CF ₂ ) ₃ CF ₂ Br, CF ₂ = CFOCH ₂ (CF ₂ ) ₃ CF ₂ Cl etc.

Next, the above-mentioned fluorine-containing vinyl ether and TFE are copolymerized. As a method of copolymerization, solution polymerization performed by dissolving the above-mentioned two kinds of monomers in an organic solvent is adopted.

In this method, the composition of each monomer unit in the obtained copolymer can be made substantially the same as the monomer composition by controlling the monomer composition to be substantially constant. As a method of making the monomer composition during polymerization almost constant, a method of performing the polymerization with the monomer composition charged before the polymerization without supplying the monomer during the polymerization, or
A method of supplying a monomer having the same composition as the monomer composition charged before the polymerization during the polymerization is adopted.

In the polymerization, in order to remove the heat of polymerization, 0.3 to 10 times by weight, preferably 1 to 5 times by weight, water of the organic solvent in the solution may be allowed to coexist in the solution in which the monomers are dissolved. Of course, TFE is usually a gas, so during polymerization,
It is preferable to pressurize and supply to the gas phase part of the polymerization reactor.

The organic solvent used in the present invention is not particularly limited,
Generally, chlorofluorocarbons and perfluoro compounds are preferably used. For example, fluorine-based solvents such as trichlorotrifluoroethane, dichlorotetrafluoroethane, trichlorofluoromethane, dichlorodifluoromethane, perfluorocyclohexane, perfluorocyclobutane, perfluorotributylamine, perfluorotriamylamine, perfluoropolyethers, etc. preferable. To specifically exemplify the polymerization method, a deoxygenated organic solvent and fluorine-containing 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, 0.1 to about 100 parts by weight of organic solvent fluorine-containing vinyl ether
It is preferable to select from the range of 30 parts by weight, preferably 1 to 10 parts by weight. Further, water may be allowed to coexist in order to facilitate removal of the heat of polymerization and stirring.

Next, in order to deoxidize the inside of the reaction vessel, for example, the operation of degassing after cooling and solidifying the content of the reaction vessel 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 compounds. 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 radical generator used cannot be unconditionally determined depending on the solvent used, the polymerization conditions, particularly the polymerization temperature, but is 0.5 to 2 relative to the fluorine-containing vinyl ether usually used for the polymerization.
A radical generator corresponding to 0 mol%, preferably 1 to 10 mol% 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~30Kg / cm 2} G proceeds, but the preferred pressure 1Kg / cm ² G~10Kg
/ cm ² G. When the TFE pressure is low, a copolymer having a low TFE content is generally obtained, and conversely, when the pressure is high, TF
The content of E 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 is usually 0 ° C to
The temperature is about 100 ° C, preferably about 5 ° C to 80 ° C. Particularly in the case of fluorine-containing or perfluoro-type diacyl peroxide, which has a large decomposition rate even at low temperatures, 5 ° C to 60
C. is preferable.

In the present invention, by carrying out the copolymerization in the presence of a chain transfer agent, the tensile strength and the melt viscosity of the obtained fluorine-containing random copolymer are improved. This trend is
This is remarkable when the monomer unit represented by the general formula [II] is in the range of 0.5 mol% or more and 10 mol% or less. Examples of the chain transfer agent used in the present invention include alcohols such as methanol and ethanol; ethers such as dimethyl ether, methyl ethyl ether and diethyl ether; methane,
Alkanes such as ethane, propane and butane are used. Among them, alcohols and alkanes are preferable for reasons such as solubility in a polymerization solvent and safety of the produced copolymer. If the chain transfer agent is a gas, it may be injected under a pressure that can maintain the required amount of dissolution in the solvent for polymerization. If it is a liquid, the required amount may be predicted or added intermittently. The amount of chain transfer agent used varies slightly depending on the type and polymerization conditions, but usually it is 0.05% based on the total amount of added monomers.
-10 mol%, preferably 0.1-5 mol%. If the amount of the chain transfer agent used is less than this range, the effect of improving the tensile strength cannot be obtained, or even if it is obtained, the decrease in melt viscosity is small. On the other hand, when the amount is too large, the tensile strength rather decreases.

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 centrifugal separator or by separating the copolymer from the solvent under reduced pressure.

The fluorine-containing vinyl ether used in the present invention is well copolymerized with TFE, and the pressure at the time of polymerization of TFE is almost 1 Kg / cm ² or more and almost copolymerized in a short time, and the conversion rate can be 100%. In such a case, almost no fluorine-containing vinyl ether is detected in the organic solvent used for the polymerization. Therefore,
The step of recovering the fluorine-containing vinyl ether is unnecessary. Conventional PPVE has poor copolymerizability when copolymerized with TFE,
As already mentioned, the recovery step is necessary, but when compared with this, this is one of the great advantages of the above-mentioned manufacturing method.

(Effect) The fluorine-containing random copolymer of the present invention contains 0.5 to 40 mol% of a monomer unit based on the fluorine-containing vinyl ether represented by the general formula [II]. Since the copolymer contained hydrogen atoms in the molecule, there was a concern that the chemical resistance was inferior, but actually the chemical resistance was surprisingly extremely good, and it was marketed as a copolymer of PPVE and TFE. Comparable to existing PFA and other perfluoro resins. Therefore, it can be used as a film, a tube, a packing material, a lining material, and other molded products in the industrial field where chemical resistance is required. It also has excellent electrical properties and can be used for connectors, substrate materials, insulating materials, etc. in the fields of electricity and electronics.

Low content of the monomer unit based on the fluorine-containing vinyl ether represented by the general formula [II], that is, 0.5 to 10 mol%
The copolymer containing is a molding material superior in mechanical properties such as tensile strength to PFA, which is a conventional copolymer of PPVE and TFE, and can be used in a wide range of fields as a molded product.

On the other hand, a copolymer containing 10 to 40 mol% of a monomer unit based on the fluorine-containing vinyl ether represented by the general formula [II] becomes a soft copolymer when compared with a copolymer having a low content. Since this copolymer has good chemical resistance, it can be used as a film or tube material requiring chemical resistance,
Furthermore, it can be used as a surface coating material for improving the chemical resistance of optical materials that require chemical resistance because it has good light transmission from the visible to the ultraviolet, and optical materials that have poor conventional chemical resistance. it can.

A soft copolymer film, a tube-shaped molded product or the like has heat-shrinkability, and can be used as a heat-shrinkable tube or film. Further, it is useful as a highly fluorinated fluororubber by introducing a crosslink.

Further, by fluorinating the fluorinated random copolymer obtained in the present invention with a fluorinating agent, for example, F ₂ , high yield can be obtained without causing the main chain cleavage observed in conventional fluorination of hydrocarbon polymers. It can be fluorinated at a rate. Therefore,
The copolymer of the present invention is also useful as a raw material for a perfluoro copolymer.

〔Example〕

 The present invention is described in detail below with reference to examples.

The measured value was obtained as follows.

1. Mechanical Properties (i) Measurement of Yield Strength, Tensile Strength and Elongation Compliant with JIS K7113 (ii) Preparation of Test Sample Fluorine-containing copolymer powder of the present invention and commercially available PFA powder and pellets for comparison are used. Pressurize under the temperature of 350 ℃,
A sheet having a thickness of 1 to 2 mm was prepared, and test pieces necessary for the above test method were prepared.

2. Thermal Properties (i) Glass Transition Temperature DSC-20 (manufactured by Seiko Instruments Inc.) was used for measurement.

(Ii) Pyrolysis temperature, melting point A thermoflex (R-TG-DTA: manufactured by Rigaku Denki Co., Ltd.) was used to measure the temperature rising rate at 5 ° C / min under a nitrogen stream.

3. Measurement of melt viscosity A high-performance melt viscosity measuring device was used.

A die having a diameter of 0.5 mm and a length of 5 mm was used, and a load of 50 kg / cm ² was applied for measurement.

4. Optical Properties The fluorine-containing random copolymer powder of the present invention was prepared according to 1- (ii) above.
A film with a thickness of 100 μm was prepared by the same method as described in the preparation of the test sample of
Absorbance to light of 50 nm was measured.

Example 1 1,1,2-trichloro 1,2,2-trifluoroethane 1, CF ₂ ═CFOCH ₂ CF ₂ CF ₃ 10 g, which was previously purified by distillation, was placed in a stainless steel autoclave 3 equipped with a stirrer, polymerization initiation As an agent (1,1,2-trichloro-1, containing 1 g of CF ₃ CF ₂ · CO _{2 2}
2,2-Trifluoroethane 10c.c. was added. The autoclave was cooled with liquid oxygen to solidify the contents, and then deaerated with a vacuum pump. Nitrogen was further introduced to a pressure of 3 Kg / cm ^{2, and} the temperature was raised while maintaining the pressure (about −
5 ° C). This operation was repeated 3 times to remove oxygen in the autoclave. Once again, it was cooled and solidified with liquid oxygen and degassed with a vacuum pump, then the temperature was raised and TF was reached when it reached about 15 ° C.
After introducing E at a pressure of 3 Kg / cm ² G and saturating and dissolving TFE,
The TFE inlet valve was closed. Set the autoclave temperature to 20.
The temperature was raised to ℃ and the polymerization was started. 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. Then, the solvent and unpolymerized CF ₂ = CFOCH ₂ C were placed in the autoclave.
A vacuum pump was connected to the trap for cooling and collecting F ₂ CF _3, and the pressure in the autoclave was reduced while stirring, and the solvent used and unpolymerized fluorine-containing 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.

When the recovered 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
It was found that CF ₂ CF ₃ was polymerized at a conversion rate of almost 100%. Approximately 97% when TFE conversion was calculated from pressure change
Met. As a result of analyzing the decomposition products at 400 ° C by pyrolysis gas chromatography mass spectrometry (hereinafter abbreviated as Py-GC / MS), CF ₃ CF ₂ CH and CF as fragments were obtained.
_{Since 3} CF ₂ CH ₃ was detected, the side chain structure was -OCH ₂ CF ₂ CF
It was confirmed to be 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%.

Examples 2 to 4 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.

Example 5 CF ₂ = CFOCH ₂ (CF ₂ ) ₂ CF ₃ 4.1 g, in a 300 ml autoclave
Further, 150 ml of 1,1,2-trichloro-1,2,2-trifluoroethane was added as a solvent and the same deoxidation operation as in Example 1 was performed. After that, TFE was introduced at a pressure of 6 kg / cm ² G, and the TFE supply valve was closed after the TFE was saturated and dissolved. After setting the temperature of the autoclave to 20 ° C, the polymerization initiator (CF ₃ CF ₂ CF ₂ C
A trichlorotrifluoroethane solution containing 0.15 g of O _{2 2}
Pressed 5 ml.

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.

Autoclave of Example _{6 300ml CF 2 = CFOCH 2 CF} 2 CF 2 Cl1.6g, as a solvent 1,1,2-trichloro-1,2,2-trifluoroethane
150 ml and 0.5 g of CF ₃ CF ₂ .CO _{2 2} as a polymerization initiator were added, and deoxidation was carried out by the procedure used in Example 1, and TFE was 3.0 kg.
/ cm ² G, and after saturated dissolution, stop the supply of TFE
Polymerization was carried out at 20 ° C. for 5 hours.

The white powder copolymer obtained was 2.7 mol% based on 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 vinyl ether.

Example 7 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.

Example 8 The thermal decomposition temperature, the melt viscosity measured at 300 ° C., and the melting point of the fluorine-containing random copolymers obtained in Examples 1 to 7 were measured,
The results are shown in Table 2. The yield strength, tensile strength and elongation of each fluorine-containing random copolymer were measured, and the results are also shown in Table 2.

Example 9 Using various fluorine-containing vinyl ethers shown in Table 3,
A fluorine-containing random copolymer was produced in the same manner as in Example 1 except that the charging ratio of the fluorine-containing vinyl ether to tetrafluoroethylene was increased. The physical properties of the obtained fluorine-containing random copolymer are shown in Table 3.

Example 10 Each fluorine-containing random copolymer obtained in Examples 1 to 7 and Example 9 was tested for chemical resistance. The results are shown in Table 4.

Example 11 Using the apparatus of Example 1, copolymerization was carried out by changing the polymerization initiator, the fluorine-containing vinyl ether and the chain transfer agent. Table 5 shows the tensile strength, melting point, melt viscosity and thermal decomposition temperature of the obtained copolymer. The content of the fluorine-containing vinyl ether unit in the copolymer was about 3 mol% in each case.

Example 12 A copolymer was synthesized by using the apparatus method and the like of Example 1 except that methanol was added as a chain transfer agent and the conversion rate of the polymerization was 85%, and the obtained copolymer was stretched. Strength,
Melt viscosity and melting point were measured. The content of the fluorine-containing vinyl ether unit in the copolymer was about 3 mol%.

Example 13 In Example 12, copolymerization was performed using ethane as a chain transfer agent instead of methanol, and the tensile strength and melt viscosity of the obtained copolymer were measured. The results obtained are shown in Table 7. The content of the fluorine-containing vinyl ether unit in the copolymer was about 3 mol% in each case.

Example 14 In order to obtain a copolymer composition curve, tetrafluoroethylene and 2,2,3,3,3-pentafluoropropyltrifluorovinyl ether were copolymerized. Freon 113 as a solvent,
As a polymerization initiator (C ₂ F ₅ · COO ₂ was used. Polymerization initiator concentration 0.3 to 1 mol% (based on all monomers), tetrafluoroethylene pressure 1 to 3 Kg / cm ² G, polymerization temperature 20 ° C, Polymerization experiments were conducted at a monomer conversion of 5 to 20 mol%, and a copolymerization composition curve was determined according to the Fineman-Ross method.The obtained results are shown in FIG. For this purpose, a copolymerization composition curve of perfluoropropyl vinyl ether and tetrafluoroethylene was calculated using the copolymerizability ratio described in “Zurnal Plyclad Hemiyah, 1984, 57 (5), 1126-8”. It is shown in FIG.

Comparative Example 1 150 ml of deoxidized water in an autoclave equipped with a stirrer of 500 c.c., CF ₂ = CFOCH ₂ CF ₂ CF ₃ 4.2 g, ammonium perfluorooctanoate 0.1 g as an emulsifier, and a polymerization initiator ( NH ₄₎ was added ₂ S ₂ O ₈ 0.2g. After deoxidizing the system, tetrafluoroethylene was injected under pressure of 6 Kg / cm ² . Polymerization was carried out for 8 hours while keeping the temperature of the autoclave at 60 ° C. and keeping the pressure of tetrafluoroethylene at 6 kg / cm ² . After the polymerization, it was filtered and dried to obtain 29 g of white powder. When a film was prepared by hot pressing and the infrared absorption spectrum was measured, about 6 mol% of CF ₂ = CFOCH ₂ CF ₂ CF ₃ was contained. The melting point of the obtained copolymer was 327 ° C., and the tensile strength was 200 Kg / cm ² . The melt viscosity was 7 × 10 ⁶ poise and the glass transition temperature was 130 ° C.

Comparative Example 2 Using the apparatus of Comparative Example 1, 15 g of CF ₂ = CFOCH ₂ CF ₂ CF ₃ was added and a polymerization experiment was conducted under the same conditions. After polymerization for 5 hours, the emulsion was filtered to obtain a copolymer. The weight of the polymer after drying was 12 g. When the polymer was used as a film for measuring an infrared absorption spectrum, white powder was recognized in the transparent film. As a result of measuring the infrared absorption spectrum, it was found that about 18 mol% of CF ₂ = CFOCH ₂ CF ₂ CF ₃ was contained. When the melting point was measured by differential thermal analysis, a small peak was recognized at 327 °. Tensile strength is 80K
The melt viscosity at 200 ° C., g / cm ² was 2 × 10 ³ , and the glass transition temperature was 130 ° C.

[Brief description of drawings]

FIG. 1 is a copolymerization composition curve in copolymerization of 2,2,3,3,3-pentafluoropropyltrifluorovinyl ether and tetrafluoroethylene. FIG. 2 is a copolymerization composition curve of perfluoropropyl vinyl ether and tetrafluoroethylene. FIG. 3 is an infrared absorption spectrum of the fluorine-containing random copolymer obtained in Example 1.

Claims (4)

[Claims] 1. A monomer unit represented by the general formula CF ₂ CF ₂ 90 to 99.5 mol%, and (B) a general formula The melt viscosity measured at 350 ° C. is 10 ² to 10 ⁷ poise and the melting point is 290
A fluorine-containing random copolymer characterized by having a temperature of up to 325 ° C. 2. A monomer unit represented by the general formula CF ₂ CF ₂ is 60 mol% or more and less than 90 mol%, and (B) the general formula It is characterized by having a monomer unit of 10 mol% or more and 40 mol% or less, a melt viscosity measured at 200 ° C. of 10 ² to 10 ⁷ poise, and a glass transition temperature of −10 ° C. or less. Fluorine-containing random copolymer to be used. 3. Tetrafluoroethylene and the general formula CF ₂ ═CFOCH ₂ (CF ₂ ) nX The fluorine-containing random ether according to claim 1 or 2, wherein the fluorine-containing vinyl ether represented by the formula (1) is dissolved in an organic solvent and copolymerized in the presence of a radical polymerization initiator. Method for producing copolymer. 4. Tetrafluoroethylene and the general formula CF ₂ ═CFOCH ₂ (CF ₂ ) nX The fluorine-containing random copolymer according to claim (1), characterized in that the fluorine-containing vinyl ether represented by the formula (1) is dissolved in an organic solvent and copolymerized in the presence of a radical polymerization initiator and a chain transfer agent. Manufacturing method of coalescence.