JPS6017327B2 - Modified ethylene↓-tetrafluoroethylene copolymer and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel ethylene-tetrafluoroethylene copolymer and a method for producing the same, and more specifically, the present invention relates to a novel ethylene-tetrafluoroethylene copolymer and a method for producing the same. The present invention relates to an improved new ethylene-tetrafluoroethylene copolymer and a method for producing the same.

Conventionally, there is no known method for copolymerizing ethylene tetrafluoride and ethylene using the action of a polymerization initiator to produce an ethylene-tetrafluoroethylene copolymer with excellent chemical resistance, heat resistance, and electrical properties. It is being

Since the copolymer has excellent properties and can be processed by hot melt molding, it can be used in a wide range of materials such as various molded products, power supply coverings, linings, and coatings. Therefore, in order to improve the high-temperature mechanical properties, particularly the high-temperature tensile properties, of the ethylene-tetrafluoroethylene copolymer, it is necessary to use a copolymer that has no telogen activity and at least 2
A method has been proposed in which an auxiliary amount of a copolymerizable vinyl monomer is copolymerized to provide a side chain containing 5 carbon atoms.
For example, Japanese Patent Publication No. 47-23671, U.S. Patent No. 3
See specification No. 624250, British Patent No. 1292643, etc. According to this method, the wire coating of ethylene-tetrafluoroethylene copolymer becomes brittle at high temperatures;
The drawback of cracking at low stress can be eliminated. However, when using a vinyl monomer having a high cage side chain as proposed in the past, it may give advantageous results for improving high temperature tensile properties, but various disadvantages are recognized for industrial implementation. .

For example, CF2=CF-C2F3, C2=CF-C4F9
When copolymerizing ethylene and tetrafluoroethylene by adding a perfluoroolefin represented by the general formula CF2=CF-Rf, the copolymerization reaction rate decreases significantly. Also, hydrofluoro such as C ratio=CH-CH2-C (CF3) 20 days or 3.

Olefins, vinyl esters, etc. reduce the heat resistance of the resulting copolymer, for example, the elongation at room temperature is 50% of the initial value.
A test to measure the heating aging time that decreases to (heating temperature 2
Examples of disadvantages include the fact that an ethylene-tetrafluoroethylene copolymer exhibiting heat resistance of 20 m hours or more at 30 qo) is reduced to a heat resistance of 80 to 100 hours or less due to the introduction of such side chains. . In particular, U.S. Pat.
In the specification of No. 2425 and the specification of British Patent No. 1292 Mouse No. 3, even if the pinyl monomer gives a bulky side chain, those containing multiple bonds in the side chain, acidic groups, ester groups, etc. are excluded. It's dark.

For example, vinyl esters, unsaturated carboxylic acids, unsaturated carboxylic acid alkyl esters, etc. are excluded. Although the reason why such vinyl monomers are excluded is not necessarily clear, it is thought that this is because heat aging resistance and other properties are poor as described above. In fact, it is difficult to improve the high-temperature tensile properties of vinyl acetate unless it is copolymerized in a considerable amount, which results in the above-mentioned deterioration in heat aging resistance and tensile crimp resistance. The present inventor has conducted various studies in order to provide a means for advantageously improving high-temperature tensile properties, etc., without impairing the excellent physical properties of the ethylene-tetrafluoroethylene copolymer as much as possible. As a result of repeated investigations, we came to the following interesting findings.

That is, the general formula CH2=CH-(0)x-(CF2)n-
When copolymerizing a small amount of various specific vinyl monomers represented by CORIR2 with tetrafluoroethylene, it is possible to copolymerize a small amount of various specific vinyl monomers represented by CORIR2 without impairing heat aging resistance, etc., even though the side chain contains a multi-bonded amide group. It has been discovered that the high-temperature tensile properties of ethylene/tetrafluoroethylene copolymers can be advantageously improved.

For example, benzoic acid vinyl ester may be used as the third component.
The initiation temperature of thermal decomposition measured by differential thermal analysis of the terpolymer obtained by polymerizing a small amount of 25 mol % was about 10° C. lower than that of the binary copolymer.

Furthermore, the copolymerization obtained using vinyl acetate as a third component was 0.
Even with a small addition of 4 mol%, significant coloring was observed in the molded product. Furthermore, these vinylesters contain 1 mol%
Addition of only a small amount had little effect on improving high-temperature mechanical strength. In contrast, the terpolymer according to the present invention had a thermal decomposition onset temperature equal to or higher than that of the binary copolymer, and no coloration of the molded product was observed. Furthermore, the high temperature tension is significantly improved even with addition of about 0.5 mol%. Thus, the present invention was completed based on the above-mentioned new findings, and the molar ratio of tetrafluoroethylene/ethylene is 40/60 to 60/40, and the general formula CQ:CH-(0) x-(CF2)n-CO
RIR2 (However, RI and R2 in the formula are each a hydrogen atom or a hard alkyl group having 1 to 1 carbon atoms, and x
is 0 or 1, n is an integer of 1 to 10) is 0.1 to 10 mol%, and the volume flow rate defined below is 10 The object of the present invention is to provide an improved ethylene-tetraethylene copolymer characterized in that it has a molecular weight of 50 mol/sec. As used herein, the term "volume flow rate" is defined as follows.

That is, using a Koka type flow tester, under a predetermined temperature and a predetermined load of 30k9/ground, nozzle diameter 1 fence, land 2
The value expressed by the volume of the molten sample extruded per unit time when extruding the sample for one night through the leg nozzle is defined as the "volume flow rate", and its unit is Yanagi 3/sec. Here, the predetermined temperature is a temperature in the temperature range (temperature range between the flow start temperature and thermal decomposition start temperature) at which the specific ethylene-tetrafluoroethylene copolymer can be molded and close to the flow start temperature. will be adopted. Therefore, for the specific copolymer of the present invention, a predetermined temperature is selected in the range of 260 to 360 o'clock, and a temperature higher than the thermal decomposition initiation temperature is not adopted. In all of the examples described below, a temperature of 300° C. was employed. In addition to the high-temperature tensile test, there is a "mandrel wrap test" (NEndreIWrapTest) as a test method for expressing high-temperature tensile properties, which is the object of the present invention.

The test method is carried out as follows. Core metal with diameter 6.4 ribs (
Mandrel), middle 6.4 side, thickness 1.3 soil 0.1
A rectangular molded sheet with a length of 127 legs is wrapped around the ribs, and both ends are fixed to the core metal with bolts and nuts. This test piece
It is left in an oven maintained at a constant temperature for 9 hours. It is known that test pieces obtained from copolymers with poor high-temperature elongation and strength crack at lower temperatures. For example, when this test is performed on a C2F4-C2 Japanese copolymer which has poor high temperature strength, cracks occur at 110 to 120 DEG C., but no cracks occur in the copolymer of the present invention even at temperatures above 200 DEG C. The discussion test is widely known in the industry as a thermal stress cracking test method for polyethylene.
It is stated in the icatjon LP39 ratio. Further, the present invention provides general formula CH2=CH-(0)x-(CF2)n-
With the addition of a small amount of a pinyl monomer having an acid amide group represented by CONRIR2, the reaction molar ratio of tetrafluoroethylene/ethylene is maintained at substantially 40/60 or more,
Modified ethylene-tetrafluoride having a content of 0.1 to 10 mol% of units blocking the vinyl monomer, characterized in that ethylene and tetrafluoroethylene are copolymerized under the action of a free radical source. A new method for producing a fluorinated ethylene copolymer is also provided.

The ethylene-tetrafluoroethylene copolymer obtained by the present invention has advantageously improved tensile strength and ultimate elongation at high temperatures, with almost no loss of the original excellent physical properties as described above. .

Therefore, the copolymer wire coating according to the invention does not become brittle at high temperatures or crack at low stresses. Therefore, the novel ethylene-tetraethylene copolymer of the present invention has a volumetric flow rate of 10 to 500 3/sec, preferably 2/sec.
0 to 30 Qiqi3/sec.

Since the volume flow rate is in the above range, it is possible to perform heat melt molding such as extrusion molding and injection molding, and it is also easy to apply braze in powder coating, dispersion coating, etc. Further, the novel copolymer suitable for the present invention has a flow initiation temperature of 24 pi or more, preferably 250 to 28 pi,
Thermal decomposition start temperature is 31 pi○ or higher, preferably 330 to 3
The temperature is 70°C. Therefore, as described above, it is easy to heat-melt mold and process, and it also has excellent heat resistance, and has improved high-temperature tensile properties while maintaining the above properties. In the present invention, in order to produce a suitable new copolymer, the reaction molar ratio of tetrafluoroethylene/ethylene is usually 2.35 or more, preferably 3 or more.

That is, in a preferred embodiment, the copolymerization is carried out so that the ratio of tetrafluoroethylene monomer to ethylene monomer in the copolymerization reaction system is maintained within the above range. For example, the charging molar ratio of ethylene tetrafluoride is selected from the above range,
For example, the copolymerization reaction is carried out while replenishing the amount consumed by the progress of the copolymerization reaction. Therefore, in the method of the present invention, the charging molar ratio of tetrafluoroethylene/ethylene is 70/30 to 90/1, preferably 75/25 to 85.
/15, while replenishing a monomer mixture having a molar ratio of tetrafluoroethylene/ethylene of 40/60 to 60/4, preferably 50/50 to 55/45 during the course of the copolymerization reaction, Preferably, a copolymerization reaction is carried out. Thus, a tetrafluoroethylene content of 40 to 60 mol%, especially 5
An ethylene-tetrafluoroethylene copolymer containing 0 to 55 mol% is obtained. In the present invention, the specific acid amide group-containing vinyl monomer has the general formula CH2=CH-(0)x-(C
F2) is represented by n-CONRIR2.

In this), x is 0 or 1, and in either case, it is effective as a modifying component, but from the point of view of easy availability, x = 0.
, x=1 is preferably selected from the viewpoint of polymerization rate. RI and R2 are each a hydrogen atom or a carbon number of 1 to 10
From the viewpoint of synthesis, preferably a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, particularly preferably a hydrogen atom. Further, n is selected from an integer of 1 to 10, preferably 2 to 5. If n is too large, there is a tendency that the melting point of a copolymer with improved high-temperature tension to the same level decreases, and especially when R1 and R2 are both hydrogen atoms, the melting point of the vinyl monomer decreases. This is undesirable because it causes various inconveniences in the polymerization operation, such as an increase in the amount of water or a decrease in solubility in the polymerization medium. The method for synthesizing such a vinyl monomer varies depending on x, but when x=0, for example, as described in US Pat. No. 3,503,945, a terminal iodo (or bromo) perfluorocarboxylic acid ester The ethylene adduct obtained by adding ethylene in the presence of a free radical generator such as azopisisoputilonitrile is dehydrogenated (or deodorized) with an alkali such as an alcoholic solution of sodium alcoholate. Hydrogenation) and then amidation of the ester moiety with ammonia or amine to obtain a terminal vinyl polyfluoroamide, or by reversing the order of dehydrohalogenation and amidation in this method. and when x=1, the ester-containing acid fluoride [ROOC(CF2)n
-, COF] with an alkali metal fluoride (MF: e.g. Cs
Alcoholate [ROO
C(CF2)nOM] is reacted with vinyl halide (CH2=CHX) in an aprotic polar solvent (e.g. dimethyl sulfoxide, dimethylformamide) to form pinylether [ROOC(CF2)nOCH=CH2]
It is possible to employ methods such as converting the ester moiety into a compound and then amidating the ester moiety with ammonia or an amine.

In the copolymerization reaction of the method of the present invention, it is desirable that the amount of the specific acid amide group-containing vinyl monomer added be as small as possible.

Usually, it is selected from a range of 0.1 to 10 mol% based on the total monomers. If the amount added is too small, the effect of improving the high-temperature mechanical properties of the resulting copolymer will not be observed, and if it is too large, the copolymerization reaction rate will be unsatisfactory for industrial implementation. At the same time, this is disadvantageous to the originally excellent physical properties of the ethylene-tetrafluoroethylene copolymer. In order to obtain industrially advantageous and excellent polymers, it is desirable that the amount of the specific acid amide group-containing vinyl monomer added be about 0.3 to 5 mol %. Regarding specific acid amide group-containing vinyl monomers, it is preferable to carry out the copolymerization reaction while maintaining the above ratio, and it is usually preferable to carry out the copolymerization reaction while replenishing the amount consumed as the copolymerization reaction progresses. be.

In the present invention, a small amount of a specific fluoropinyl ether is copolymerized and contained in the produced copolymer, but usually 0
．． The content is desirably about 1 to 10 mol%, particularly about 0.3 to 5 mol%. Therefore, during the progress of the copolymerization reaction, 0.1 to 10 mol%, preferably 0.3 mol%, of a specific acid amide group-containing vinyl mo/mer is added together with tetrafluoroethylene and ethylene.
Replenishment at a concentration of ~5 mole % is desirable. Thus,
An ethylene-tetrafluoroethylene copolymer is obtained in which 0.1 to 10 mol%, preferably 0.3 to 5 mol%, of a specific acid amide group-containing vinyl monomer is copolymerized. The content of the specific vinyl monomer in the produced copolymer is calculated from the difference between the amount of each monomer introduced into the polymerization tank and the amount of each monomer recovered after completion of polymerization. If the content of the specific acid amide group-containing vinyl monomer in the resulting copolymer is too small, no improvement in high-temperature mechanical properties will be observed, but if it is too large, the ethylene-tetrafluoroethylene copolymer will If the tensile creep and heat aging resistance of the ethylene-tetrafluoroethylene copolymer are too high, the tensile creep and heat aging resistance of the ethylene-tetrafluoroethylene copolymer will decrease, resulting in an excessively soft product.

The ethylene-tetrafluoroethylene copolymer obtained by the present invention has a tensile strength, ultimate elongation, Each degree is ~
20k9/enemy, ~40%, while 30% each
kg/kg, especially 40-80k9/kg, is improved by 200% or more, especially 400-600%, and the drawback that the wire coating becomes brittle at high temperatures and cracks at low stress is eliminated. The copolymerization reaction in the method of the present invention can be carried out using well-known or conventional methods under the action of polymerization initiators such as peroxy compounds, azo compounds, ultraviolet light, and ionizing radiation, with or without the use of inert organic solvents or aqueous media. This can be done by such means as

Moreover, various polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and gas phase polymerization can be employed as the polymerization method. According to the research of the present inventor, a solvent consisting of a fluorinated or fluorinated chlorinated saturated hydrocarbon known as a so-called fluorocarbon solvent, preferably having a carbon number of 1, is used as the copolymerization reaction medium. It is advantageous to use ~4, especially 1 to 2, in terms of producing an ethylene-tetrafluoroethylene copolymer with excellent heat resistance, moldability, chemical resistance, and other properties. It has been recognized that controlling the reaction conditions and maintaining the copolymerization reaction rate can also provide advantageous results for industrial implementation.

Examples of chlorofluorocarbon solvents include dichlorodifluoroqmethane, trichloromonofluoromethane, dichloromonofluoromethane, monochlorodifluoromethane, chlorotrifluoromethane, fluoroform, tetrafluoroethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, and hexane. Examples include fluoroethane, fluorochloropropane, perfluoropropane, fluorocyclobutane, perfluorocyclobutane, etc., which may be used alone or in a mixture of two or more. According to the research of the present inventor, fluorinated systems that do not contain hydrogen atoms in their molecules, such as dichlorodifluoromethane, trichloromonofluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, and perfluoroclobutane, Alternatively, when using a solvent made of a fluorinated chlorinated saturated hydrocarbon, preferably one having 1 to 4 carbon atoms, particularly 1 to 2 carbon atoms, the molecular weight of the resulting copolymer can be increased; Recognized as particularly desirable in other areas. In the method of the present invention, when using a fluorocarbon solvent, the amount used is not particularly limited, but usually the solvent is The amount is preferably about 0.05 to 20 mol, particularly about 1 to 10 mol.

Although it is possible to carry out the copolymerization reaction even if the amount of solvent used is less than 0.05 mol per mol of monomer, it is necessary to increase the copolymerization reaction rate by using industrially advantageous operations and conditions. For this purpose, it is advantageous to use 1 mol or more.
Although it is possible to use more than 20 moles of the solvent, it is advantageous to use 10 moles or less mainly for economical reasons such as recovering the solvent after the reaction. Furthermore, in the method of the present invention,
It is also possible to use a mixture of other organic solvents or aqueous media with the fluorocarbon solvent.

For example, it is possible to employ a mixed reaction medium of fluorocarbon-based solvent and water, and by this means, good results can be achieved in terms of reduction of copolymerization reaction system, ease of reaction heat removal, etc. It is. In the method of the present invention, the copolymerization reaction conditions can be varied depending on the polymerization initiation source, reaction medium, etc., but when a fluorocarbon solvent is used, the reaction temperature is usually -50°C to 1150°C. degree is advantageously adopted industrially. An appropriate reaction temperature is selected according to the type and amount of the solvent used, the molar ratio of the monomers, the amount of the specific acid amide group-containing vinyl monomer added, the type of polymerization initiation source, etc. However, if the temperature is too high, It is desirable to adopt the above range because the reaction pressure becomes excessive and the copolymerization reaction rate falls below an industrially satisfactory level at too low a temperature. Incidentally, it is sufficient for the reaction pressure to be normal pressure or slightly increased pressure, and usually about 2 to 50 k9/gauge is employed, and higher or lower pressures may also be employed as appropriate. In the method of the present invention, various polymerization initiation sources can be appropriately employed depending on the polymerization method, and there is no particular reason to limit the source.

However, when using fluorocarbon-based solvents, cobalt-
It is desirable to employ ionizing radiation such as Y-rays from 60 or cesium-137, or an oil-soluble radical polymerization initiation source such as a peroxy compound or an azo compound. For example, ionizing radiation can be employed at a dose rate of 10 to 1 pyrad/hour, and peroxy compounds include organic peroxides such as benzoyl/f-oxide, lauroyl/g-oxide, and t-butyl peroxide. Peresters such as sobutyrate, diisopropyl peroxydicarbonate, etc. are generally used, and as the azo compound, radical initiators such as azobisisoptylonitrile are generally used. The amount of radical initiator used must be selected appropriately depending on the polymerization conditions employed, that is, the amount of specific fluorovinyl ether added, the medium used, the polymerization temperature, etc., but it is usually In contrast, a concentration of about 0.0001 to 2% by weight may be adopted. Ethylene preferred in the present invention
In order to obtain a tetrafluoroethylene copolymer, a fluorocarbon solvent is used as a polymerization initiation source, and the general formula (in the formula, R
It is particularly preferred to use radical initiators of the peroxyester type.

It is advantageous in terms of copolymerization reaction rate, various physical properties of the produced copolymer, copolymerization reaction operation and conditions, etc. R and RI are aliphatic alkyl groups, and the number of carbon atoms is not particularly limited, but depending on the copolymerization reaction temperature, both R and RI may have 3 to 3 carbon atoms.
It is desirable to have about 13 alkyl groups.

For example, t-butylperoxyisobutyrate, t-butylperoxyacetate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, etc. I can do it. The amount of the /f-oxyester type radical initiator used is 0.001 parts by weight of the total monomer 10.
A concentration of about parts by weight or more is sufficient.

Preferably, the radical initiator concentration in the fluorocarbon solvent is
The amount is about 0.005 to 5 parts by weight per 100 parts by weight of the total monomers. The fluorocarbon solvent is used in an amount of about 1 to 10 moles, particularly about 1.5 to 5 moles, per mole of the monomer mixture. In addition, the copolymerization reaction temperature is usually 30 to 1
A temperature of about 20 oo may be adopted, but it is desirable to select the optimum temperature in consideration of the half-life of the peroxyester type radical initiator used. For example, the temperature is 50 to 80°C for t-butylperoxyisobutyrate, and 40 to 60°C for t-butylperoxypivalate. By employing such a reaction temperature, it is possible to obtain a new copolymer in a good yield without requiring a long time. In addition, when a fluorocarbon solvent is used in the method of the present invention, the solvent can be easily separated from the produced copolymer together with the reaction monomer after the copolymerization reaction is completed.

Furthermore, since excessive reaction pressures such as those in copolymerization reactions carried out in an aqueous medium can be suppressed, ethylene-tetrafluoroethylene copolymers having excellent physical properties can be produced safely without employing high temperatures and high pressures. Moreover, in this case, the copolymerization reaction rate is industrially satisfactory as described above. This description is not intended to limit the invention in any way. Next, examples of the present invention will be described in more detail, but it goes without saying that the present invention is not limited by such explanations.

In addition, in the following examples, the physical properties of the copolymer were measured by the following method. [Tensile strength and elongation at high temperatures] Measured using JISI dumbbells according to ASTM D-638.

Measurement conditions: 200qo, 20Q snout/min (tensile speed)
Example 1 Inner Volume 2 Add trichloromonofluoromethane to the autoclave.

Trifluoromethane 825 evening, triku. Lotrifluoroethane 1125%, 3,3,4,4,5,5-hexafluoro5-rubamoyl-1-pentene (CH2=C
HCF2CF2CF28CON Day 2: 4.84 hours (hereinafter abbreviated as HCP) and 0.43 hours of t-butylperoxyisobutyrate were charged, and then 250 hours of tetrafluoroethylene was charged.
In the evening, add 17.5 tons of ethylene. This mixture was sufficiently stirred and maintained at a reaction temperature of 65q0 to carry out a copolymerization reaction. During the copolymerization reaction, the molar ratio of tetrafluoroethylene/ethylene/HCP in the system was 53/46.3/0.
A mixed gas of ethylene tetrafluoride and a heated solution of HCP in trichlorofluoroethane are introduced at a pressure of 15k9, and the polymerization pressure is maintained at 15k9. After 3 hours, a white copolymer of 72 mm was obtained.

The copolymer had a C2F4/C2/HCP molar ratio of 53/46.3/0.7, a melting point of 267°C, and a thermal decomposition initiation temperature of 360°C. The volumetric flow rate of the copolymer is 85 m3/sec, and from this copolymer,
The sheet obtained by heat compression for 0 minutes was milky white and translucent, and no signs of coloration due to thermal decomposition were observed. The tensile strength and elongation at break of the molded sheet (thickness: 1.3 mm) at 200 oo are 35 kg/, 490, respectively.
%Met. Example 2 A reaction was carried out under the same conditions as in Example 1, except that 726 g of trichloromonofluoromethane and 126 g of trichlorotrifluoroethane were charged into an autoclave.

As a result, a white copolymer with a weight of 83 mm was obtained after 4 hours. The monomer composition, melting point, and thermal decomposition initiation temperature of the copolymer were the same as those of the copolymer obtained in Example 1. The volumetric flow rate of the copolymer was 50 μ/sec, and 200 μ/sec.
The tensile strength and elongation at break at qo are 52k9/
No, it was 580%. 22 in the mandrel wrap test
No cracks occurred in the test piece even at 000. Example 3 3-oxa-4,4,5,5,6,6- instead of HCP
Hexafluoro-6-carbamoyl-1-hexene (C
H2=CHOCF2CF2CF2CON Day 2: Below OH
The reaction was carried out under the same conditions as in Example 1, except that CH) was used.

As a result, a white copolymer having a weight of 81 mm was obtained after 3 hours. The molar ratio of ethylene tetrafluoride/ethylene/OHCH in the copolymer was 53/46.3/0.7, the volume flow rate was 83 Yanagi 3/sec, and the tensile strength at 200°C was The mating ratio was 42 kg/young and 480%, respectively. In the mandrel lap test, no cracks appeared in the test piece even at 0°C. Example 4 The initial amounts of trichloromonofluoromethane, trichlorotrifluoroethane, HCP, tetrafluoroethylene, and ethylene were set to 742 nights, 1238 nights, 10.4 nights, 250 nights, and 16.2 nights, respectively, and tetrafluoride was prepared. The additional charge molar ratio of ethylenenoethylene/HCP is 53/45.5/1
．． The reaction was carried out under the same conditions as in Example 1 except that the reaction time was changed to 5, and a white copolymer of 80 mm was obtained after 5 hours.

The copolymer has a molar ratio of tetrafluoroethylene/ethylene/HCP of 53/45.5/1.5, a melting point of 25%,
The thermal decomposition onset temperature was 3°C. The volumetric flow rate of the copolymer was 8 cubic meters per second, and the tensile strength and elongation at break at 200 qo of a sheet formed in the same manner as in Example 1 were 55 k9/base and 700%, respectively. . Further, in the mandrel wrap test, no cracks were observed at temperatures above 220 pm, and no cracks were observed even at 250 pm, which is close to the melting point. Comparative Example In place of HCP in Example 1, 3, 3, 4, 4, 5,
3-hexafluoro-5-cyano-1-pentene (CH
A similar polymerization reaction was carried out using CHCF2CF2CF2CN), but in this case, the yield of copolymer after 5 hours was less than 14.

Claims (1)

[Claims] 1. The molar ratio of tetrafluoroethylene/ethylene is 40/6.
0 to 60/40, and the general formula CH_2=CH-(O)
＿x-(CF_2)_n-CONR^1R^2 (However,
In the formula, R^1 and R^2 are each a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and x is 0 or 1.
, n is an integer of 1 to 10), the content of units based on a vinyl monomer having an acid amide group is 0.1 to
10 mol%, and the volumetric flow rate is 10 to 500 mm^3/
A modified ethylene-tetrafluoroethylene copolymer characterized by having a 2 A vinyl monomer having an acid amide group has the general formula CH_
2=CH-(O)_x-(CF_2)_m-CONH_
2 (in the formula, x is 0 or 1, and m is an integer of 2 to 6). 3. The copolymer according to claim 1, wherein the content of units based on vinyl monomers having acid amide groups is 0.3 to 5 mol%. 4 The molar ratio of tetrafluoroethylene/ethylene is 50/5
The copolymer according to claim 1, which has a molecular weight of 0 to 55/45. 5. The copolymer according to claim 1, which has a volumetric flow rate of 20 to 300 mm^3/sec. 6 General formula CH_2=CH-(O)_x-(CF_2)
_n-CONR^1R^2 (However, R^1 and R^ in the formula
2 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, x is 0 or 1, and n is an integer of 1 to 10). The method is characterized in that ethylene and tetrafluoroethylene are copolymerized under the action of a free radical generator, with the reaction molar ratio of tetrafluoroethylene/ethylene substantially maintained at 40/60 or more. A method for producing a modified ethylene/tetrafluoroethylene copolymer having a content of units based on the vinyl monomer of 0.1 to 10% by mole. 7 General formula C as a vinyl monomer having an acid amide group
H_2=CH-(O)_x-(CF_2)_m-CON
7. The method according to claim 6, wherein H_2 (where x is 0 or 1 and m is an integer from 2 to 6) is used. 8 The molar ratio of tetrafluoroethylene/ethylene was 75/2.
5 to 85/15, and the molar ratio of tetrafluoroethylene/ethylene is 50/50 to 55 during the progress of the copolymerization reaction.
7. The method according to claim 6, which is carried out while supplementing the monomer mixture of: /45. 9 In a medium made of fluorinated or fluorinated chlorinated hydrocarbons, there are general formulas ▲mathematical formulas, chemical formulas, tables, etc. as sources of free radicals▼ (However, R and R^1 in the formula are aliphatic 7. The method according to claim 6, which uses a peroxyester type compound of (which is an alkyl group) and is carried out at a reaction temperature of 30 to 120°C.