JP2915219B2 - Fluorine-containing copolymer and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, molded products of improved fluororesin, particularly less content of oligomer components, consisting of a copolymer of enhanced tetrafluoroethylene and fluorinated vinyl ether of the mechanical strength molded Object and the molding
The present invention relates to a method for producing a fluorine-containing resin for products .

[0002]

2. Description of the Related Art A copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (hereinafter referred to as PFA) is well known as a meltable fluororesin, and is a molded product such as a tube, a pipe, a joint, and a container. And widely used for coating, lining and the like. In particular, in the semiconductor manufacturing process, it is widely used as a material for piping such as wafer carriers, bottles and tubes because of its excellent chemical resistance and heat resistance.

[0003]

SUMMARY OF THE INVENTION However, PFA
However, there are some problems in detail. That is, PFA elutes particles relatively more in comparison with general-purpose resins such as polyethylene, and is highly integrated LSI.
When used as various containers or jigs for manufacturing, it causes a decrease in yield, and therefore there is a strong demand for reduction of particles.

[0004] In the dilute hydrofluoric acid immersion test after the extraction of PFA with Freon-113, the rate of increase in the amount of generated particles over time was reduced. One of the causes of particles generated from PFA was oligomers contained in PFA. Is believed to be. Therefore, as a method of particle reduction, processes such as cleaning of the PFA molded body, fluorine gas treatment, and air purging during molding have been attempted, and as a result, the initial generation amount of particles has been reduced (Ultra Clean Technology Vol. 463 pages, 1
990). However, all of these methods are surface treatments, and the oligomers are eluted from the inside of the resin with the lapse of time, so that there is no fundamental solution at present.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on a molded article of a fluororesin having a small amount of particles, that is, a fluororesin having a small amount of an oligomer component. The inventors have found that a fluorine-containing copolymer having a very low oligomer content can be obtained by the addition, and the present invention has been completed.

That is, the present invention relates to a compound represented by the general formula (II): 90 to 99.5 mol% based on the general formula (I)-(CF ₂ CF ₂ )-(I)

[0007]

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(Where Rf is a halogenated hydrocarbon group), comprising 10 to 0.5 mol% of a monomer unit having a specific melt viscosity of 10 ² to 10 ⁷ poise measured at 372 ° C. A molded article of a fluorinated copolymer, characterized in that the weight loss by extraction with a fluorinated organic solvent is 0.01% by weight or less.

The present invention also relates to a compound of the formula (I)-(CF ₂ CF ₂ )-(I) having a monomer unit content of at least 60 mol% and less than 90 mol%, and

[0010]

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(Where Rf is a halogenated hydrocarbon group), comprising more than 10 mol% and less than 40 mol% of a monomer unit, and having a specific melt viscosity of 10
From ² to 10 ⁷ poises, the weight loss by extraction of the fluorine-containing organic solvent is a molded product of the fluorocopolymer, characterized in that at most 0.01 wt%.

The monomer unit represented by the general formula (I) is a monomer unit based on the polymerization of tetrafluoroethylene.

In the monomer unit represented by the general formula (II), the group represented by Rf is generally a halogenated hydrocarbon group. Particularly preferred groups in the present invention are a perfluoroalkyl group and a perfluoroalkyl group. following general formula _{(IV) -CH 2 C a F} b X c H (2a + 1-bc) (IV) ( where, X is a chlorine atom or a bromine atom, a is an integer of 1 or more, b is Is an integer of 0 to 2a + 1, c is 0 or 1, and has a relationship of 1 ≦ b + c ≦ 2a + 1.) The number of carbon atoms in the halogenated hydrocarbon group represented by Rf is not particularly limited, but is preferably 1 to 8 carbon atoms from the viewpoint of availability of raw materials.

In the present invention, among the monomer units represented by the general formula (II), when Rf is the general formula (IV), the fluorine-containing copolymer of the present invention has an oligomer content of And has a good tensile strength at break. The reason for this is that in the method for producing a fluorine-containing copolymer of the present invention described later, Rf is represented by the general formula (I
It can be considered that this is because the monomer V) has higher polymerizability than the monomer which is a perfluoroalkyl group, and thus has a large effect of preventing the formation of oligomer components in the monomer removal step.

The composition of each monomer unit represented by the general formulas (I) and (II) is such that the unit represented by the general formula (I) is 60 to 99.5 mol%, The unit represented by II) is 40 to 0.5 mol%. When the amount of the monomer unit represented by the general formula (II) is less than the above range, the melt viscosity becomes too high, resulting in a copolymer having poor moldability. Conversely, when the amount is more than the above range, the copolymer becomes soft. Since the temperature is lowered, there is a problem in moldability, which is not preferable. In consideration of the moldability of the fluorine-containing copolymer of the present invention, the monomer units represented by the general formulas (I) and (II) account for 75 to 99.5 mol% and 25 to 0.5 mol%, respectively. And more preferably 90 to 99 mol% and 10 to 1 mol%, respectively.

The fluorine-containing copolymer used in the present invention is a random copolymer in which the monomer units represented by the general formulas (I) and (II) are randomly arranged . And since it is insoluble in various solvents, the molecular weight cannot be determined by ordinary means. However, the specific melt viscosity of the fluorine-containing copolymer of the present invention as they depend on the molecular weight, it is possible to estimate the molecular weight by measuring the specific melt viscosity. That is, before following general formula (II) monomer unit represented by is in the range of 0.5 to 10 mol% copolymer, 372
The specific melt viscosity measured at ° C is in the range of 10 ² to 10 ⁷ poise. Further, the copolymer in which the monomer unit represented by the general formula (II) is more than 10 mol% and not more than 40 mol% is 2
The specific melt viscosity measured at 00 ° C. is in the range of 10 ² to 10 ⁷ poise. In any case, the specific melt viscosity is preferably in the range of 10 ³ to 10 ⁶ poise in consideration of the moldability of the copolymer.

Further, the fluorine-containing copolymer used in the present invention has a tensile strength at break of 250 kg / cm ² or more measured according to JIS K-7113, and has sufficient physical properties in mechanical strength. I have. The above tensile strength at break may be 300 kg / cm ² or more.

Further, the oligomer contained in the molded article of the fluorinated copolymer of the present invention can be extracted with a fluorinated organic solvent.
It can be quantified by weight loss after extraction. The molded article of the fluorinated copolymer of the present invention has a weight reduction rate of 0.01% by weight or less when extracted with a fluorinated organic solvent, and can be 0.008% by weight or less.

As the fluorinated organic solvent used for extracting the oligomer in the fluorinated copolymer, a known organic solvent having a fluorine atom in the molecule can be used without any limitation. Specific examples of the fluorine-containing organic solvent that can be preferably used in the present invention include, for example, CFCl ₂ CF ₂ C
1 (CFC-113), CH ₃ CCl ₂ F (CFC-14)
1b).

[0020] Using the above fluorine-containing organic solvent, the fluorocopolymer molding a conventional fluorine-containing copolymer formed according to the present invention
Comparing the weight loss rates of the shaped articles , it can be said that the weight loss of the fluorine-containing copolymer molded article of the present invention is extremely low and the content of the oligomer component is small.

The chemical structure of the fluorinated copolymer used in the present invention can be confirmed by measuring its infrared absorption spectrum (hereinafter simply referred to as IR). That is, in the monomer unit represented by the general formula (II), when Rf is a perfluoroalkyl group, the vicinity of 990 cm ^-1 >
A CFOCF ₂ — group and —CF ₂ — near 1200 cm ⁻¹
Having an absorption band based on a group represented by the general formula (I
In the monomer unit represented by I), Rf is the same as that of the general formula (IV)
For a group represented by around 950cm ^-1> CFOCH
₂ - has an absorption band based on the group - -CH ₂ near groups and 2900 cm ^-1.

The fluorinated copolymer used in the present invention may be produced by any method, but is particularly preferably produced by the following method.

That is, tetrafluoroethylene is copolymerized with a fluorine-containing vinyl ether represented by the following general formula (III) CF ₂ ＣＦCFORf (III) (where Rf is a halogenated hydrocarbon group), and a polymerization terminator is used. This is a method in which unreacted monomers are removed after the addition.

As the halogenated hydrocarbon group represented by Rf in the general formula (III), the same group as Rf in the general formula (II) can be employed. Specific examples of the fluorine-containing vinyl ether represented by the general formula (III) used in the present invention include: CF ₂ ＣＦCFOCH ₂ CF ₃ , CF ₂ ＣＦCFOCH ₂ CF ₂
CF ₃ , CF ₂ ＣＦCFOCH ₂ CF ₂ CF ₂ H, CF ₂ ＣＦCFOC
_{H 2 (CF 2) 2 CF} 3, CF 2 = CFOCH 2 (CF 2) 3 CF 3, CF 2 = CFO
CH ₂ (CF ₂ ) ₄ CF ₃ , CF ₂ ＣＦCFOCH ₂ (CF ₂ ) ₅ CF ₃ , CF ₂ ＣＦCFO
CH ₂ (CF ₂ ) ₆ CF ₃ , CF ₂ ＣＦCFOCH ₂ (CF ₂ ) ₇ CF ₃ , CF ₂ ＣＦCFO
_{CH 2 CF 2 Cl, CF 2} = CFOCH 2 CF 2 Br, CF 2 = CFOCH 2
CF ₂ CF ₂ Cl, CF ₂ ＣＦCFOCH ₂ CF ₂ CF ₂ Br, CF ₂ ＣＦCFO
_{CH 2 (CF 2) 2 CF} 2 Cl, CF 2 = CFOCH 2 (CF 2) 2 CF 2 Br, CF 2 = CFOCH 2 (CF 2) 3 CF 2 Cl, CF 2 = CFOCH 2 (CF 2) 3 CF _{2 Br, CF 2 = CFOCF 3} , CF 2 = CFOCF 2 CF 3, CF 2 = CFO (CF 2) 2 CF 3, CF 2 = CFO (C
F ₂ ) ₃ CF ₃ , CF ₂ ＣＦCFO (CF ₂ ) ₄ CF ₃ , CF ₂ ＣＦCFO (C
F ₂ ) ₅ CF ₃ , CF ₂ ＣＦCFO (CF ₂ ) ₆ CF ₃ , CF ₂ ＣＦCFO (C
F ₂ ) ₇ CF ₃ , CF ₂ ＣＦCFO (CF ₂ ) ₈ CF _{3 and the} like.

In the present invention, the charged composition of tetrafluoroethylene and the fluorinated vinyl ether represented by the above general formula (III) is such that the melt viscosity of the obtained fluorinated copolymer is not so large and the softening temperature is set to an appropriate value. In order to facilitate the forming process by maintaining the above-mentioned formula (III)
Is preferably in the range of 0.5 to 40 mol%, and tetrafluoroethylene is in the range of 99.5 to 60 mol%.
0.5 to 25 of the fluorine-containing vinyl ether represented by I)
It is preferable that the mole% and the amount of tetrafluoroethylene are in the range of 99.5 to 75 mole%.

Further, a fluoroolefin such as hexafluoropropylene, chlorotrifluoroethylene or vinylidene fluoride may be added to tetrafluoroethylene in order to modify the properties of the obtained copolymer. Generally, it is preferable to use 5 mol% or less based on tetrafluoroethylene.

The method of copolymerizing the above-mentioned fluorine-containing vinyl ether with tetrafluoroethylene is not particularly limited, and a known method is employed. That is, any method such as a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method is adopted, and an optimum polymerization method may be selected according to conditions such as copolymerizability of the monomer.

First, the solution polymerization method will be specifically described. The polymerization solvent used is not particularly limited, but chlorofluorocarbon, chlorofluorohydrocarbon, perfluorocarbon and the like are generally suitably used. In the case of solution polymerization, 0.3 to 10 times by weight, preferably 1 to 10 times by weight in a polymerization solvent is used to remove polymerization heat.
It is also possible to carry out polymerization in the presence of up to 5 times the weight of water.

As the polymerization initiator, known radical generators can be employed, but in consideration of the heat resistance of the obtained copolymer, fluorine-containing radical generators are preferred. For example, [Z (CF ₂ ) _y CO ₂ ] ₂ (where Z is a hydrogen atom, a fluorine atom or a chlorine atom, and y is an integer of 1 to 5)

[0030]

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(Where Z is a hydrogen atom, a fluorine atom or a chlorine atom, y is an integer of 1 to 5, and q is 0 to 0)
It is an integer of 3. ) Can be suitably used. Specific examples of the radical generator suitably used in the present invention include (HCF ₂ CF ₂ CO ₂ ) ₂ , (CF ₃ CF ₂ CO ₂ ) ₂ , (C
_{F 3 CF 2 CF 2 CO 2} ) 2, (CF 3 CF 2 CF 2 CF 2 CO 2) 2, (ClCF 2 CF 2 C
O ₂ ) ₂ ,

[0032]

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The following can be mentioned.

The amount of the radical generator used cannot be determined unconditionally depending on the solvent used, the polymerization conditions, and particularly the temperature.
Mol%, preferably in the range of 0.005 to 0.2 mol%. Further, the radical generator may be introduced all at once at the start of the polymerization, or may be introduced intermittently during the polymerization. In particular, depending on the conditions, the polymerization may be difficult to proceed on the way, but in such a case, it is an effective means to add the radical generator again in the middle.

The polymerization temperature is determined based on the decomposition rate of the radical generator to be used as one standard.
° C, preferably 5 to 60 ° C.

Next, suspension polymerization will be described. The polymerization initiator, the amount used and the polymerization temperature in the suspension polymerization can be carried out in the same manner as in the solution polymerization. In suspension polymerization, it is preferable to use a dispersion stabilizer. Known dispersion stabilizers are employed without any limitation,
Ammonium perfluorocarboxylate, ammonium perfluorosulfonate, polyvinyl alcohol, and the like are used. In particular, in view of the effect of dispersion stability and the thermal stability of the obtained fluorinated copolymer, the number of carbon atoms is 5 to 10 Ammonium perfluorocarboxylates having a chain alkyl group are preferred. From the viewpoint of dispersion stability, chlorofluorocarbon and perfluorocarbon may be used in addition to the above-mentioned dispersion stabilizer, and the amount thereof is preferably 0.1 to 1 times the weight of water.

The emulsion polymerization will be further described. In the emulsion polymerization, a water-soluble radical generator is used as a polymerization initiator, and usually an inorganic peroxide such as ammonium persulfate or potassium persulfate is preferably used. Can be The polymerization temperature is from 20 to 140C, preferably from 40 to 100C. Oite the emulsion polymerization is good by using a dispersion stabilizer, the type and amount are as described above suspension polymerization. In emulsion polymerization, a buffer such as ammonium carbonate may be used without any problem.

In any of the polymerization methods, if the pressure of tetrafluoroethylene is in the range of 1 to 30 kg / cm ² -G, the polymerization reaction proceeds sufficiently, but if the pressure is too high, the apparatus becomes considerably expensive. Is usually preferred to be 1 to 10 kg / cm ² -G.

As for the supply of the above monomer components to the polymerization tank, a predetermined amount of tetrafluoroethylene and fluorine-containing vinyl ether may be sealed in the polymerization tank for polymerization, or the polymerization of tetrafluoroethylene and fluorine-containing vinyl ether may be carried out. One or both of tetrafluoroethylene and fluorinated vinyl ether may be added continuously or intermittently during the polymerization depending on the amount consumed by the polymerization.

Further, in any of the polymerization methods, it is preferable to add a necessary amount of a chain transfer agent for controlling the molecular weight. Chain transfer agents include chlorinated hydrocarbons such as carbon tetrachloride and chloroform; hexane, pentane, butane,
Alkanes such as propane, ethane, and methane; ethers such as diethyl ether and dimethyl ether; alcohols such as methanol and ethanol can be used. Among them, the amount dissolved in the polymerization solvent and the amount of the resulting copolymer Alkanes and alcohols are preferred for reasons such as stability. If the chain transfer agent is a gas, it may be injected at a pressure that can maintain a necessary amount of dissolution in the polymerization solvent. In the case of a liquid, the necessary amount may be added in advance or intermittently. The amount of the chain transfer agent varies within a certain range depending on the type of the chain transfer agent and the polymerization conditions, but is usually 0.05 to 10 mol%, preferably 0.1 to 10 mol%, based on the total amount of monomers in the polymerization tank. Preferably it is in the range of 5 mol%. Here, when water is present in the polymerization system, it is preferable to add the chain transfer agent so that the concentration of the chain transfer agent in the organic phase is within the above range in consideration of the distribution ratio between the aqueous phase and the organic phase of the chain transfer agent.

In the method of the present invention, after performing the above copolymerization, a polymerization terminator is added to stop the polymerization reaction. The polymerization terminator can be used without any particular limitation as long as it is a compound capable of substantially stopping the polymerization reaction. Specifically, alcohols such as methanol and ethanol;
Hydrocarbons such as hexane, pentane and butane; chlorinated hydrocarbons such as carbon tetrachloride and chloroform; terpenes such as limonene, cymene and pinene; quinones such as benzoquinone and naphthoquinone; phenols such as hydroquinone, cresol and catechol. Alcohols, hydrocarbons, chlorinated alcohols, etc., because of the efficiency of termination of the polymerization reaction, separation from the fluorinated copolymer, and thermal stability of the obtained fluorinated copolymer. Hydrocarbons are preferred.

The amount of the polymerization terminator to be added cannot be determined unconditionally depending on the polymerization method, the efficiency of the polymerization terminator to be added, and the like. However, it is usually used in an amount of 20 mol% or more based on the amount of unreacted monomer remaining in the polymerization system. If this is the case, the efficiency of stopping the polymerization reaction will increase.
And from the viewpoint of separation of the fluorine-containing copolymer of the present invention from the polymerization terminator, the range of 20 to 300 mol% is preferred.
Particularly preferred.

Incidentally, the remaining amount of the unreacted monomer can be determined as follows. For example, the amount of unreacted tetrafluoroethylene can be calculated from the reactor pressure, temperature and solubility of tetrafluoroethylene in the polymerization solvent, and the amount of unreacted fluorine-containing vinyl ether is roughly calculated from the amount introduced into the reactor and the amount of tetrafluoroethylene consumed. Can be estimated.

The addition of the polymerization terminator is effective at any stage as long as the unreacted monomer remains in the polymerization system after the polymerization reaction has started. However, it is inconvenient from the viewpoint of productivity of the fluorine-containing copolymer if it is too early in the polymerization, and if the polymerization reaction proceeds too much and the polymerization system becomes high in viscosity, it becomes difficult to uniformly stir. As a result, the removal of the heat of polymerization becomes insufficient, which may adversely affect the physical properties of the obtained copolymer. Therefore, the timing of adding the polymerization terminator may be determined from the viewpoint of the physical properties and productivity of the obtained fluorinated copolymer, but usually the concentration of the fluorinated copolymer in the reaction solution is 2 to 3
It is preferably at the time when the weight becomes 0% by weight, preferably 3 to 20% by weight.

The method of adding the polymerization terminator is not particularly limited, but may be a method in which the polymerization terminator is injected into the polymerization system, a method in which the polymerization reaction solution is transferred to a vessel containing the polymerization terminator, a method in which unreacted tetrafluorocarbon is added. For example, a method of introducing a polymerization terminator immediately after depressurization due to the release of ethylene may be mentioned.

In the present invention, unreacted monomers are removed after the addition of the polymerization terminator. The removal of the unreacted monomer is to remove at least one of the unreacted tetrafluoroethylene and the unreacted fluoroalkyl vinyl ether, and the operation can employ a known monomer removal method. For example, the operation of releasing gaseous tetrafluoroethylene from the gas phase of the polymerization tank, the unreacted tetrafluoroethylene and unreacted fluoroalkyl vinyl ether dissolved in the polymerization solvent are contained by means such as filtration, centrifugation, heating, and decompression. An operation of separating from the fluorine copolymer can be given.

The produced fluorine-containing copolymer is obtained by separating an unreacted monomer, solvent, excess polymerization terminator and the like from the polymerization reaction mixture.

Among the fluorinated copolymers used in the present invention , those having a hydrogen atom in the molecule are fluorinating agents, for example,
By fluorinating using F ₂ , it can be fluorinated in a high yield without causing the main chain scission observed in the fluorination of conventional hydrocarbon polymers, and to be a perfluoro copolymer Can be.

In the present invention, a molded article of the fluorine-containing copolymer
There is no particular limitation on the method for obtaining
Molded products such as tubes, pipe fittings, containers, coatings,
Includes linings and other moldings.

[0050]

When the particles produced by immersing the fluorine-containing copolymer molded article of the present invention in hydrofluoric acid are measured, the amount of particles generated at the initial stage is not only extremely small but also does not increase even after a lapse of time. In addition, Freon-113 and Freon-1
The weight loss when extracted with a fluorine-containing organic solvent such as 41b is extremely small, not more than 0.01% by weight. From this,
It can be said that the fluorine-containing copolymer molded article of the present invention has an extremely low content of the oligomer component. Further, it is considered that a component causing particles other than the oligomer component is contained in the fluororesin. However, since the amount of generated particles of the fluorinated copolymer of the present invention is extremely low, the component other than such an oligomer may be used. It is considered that the components that cause the particles are also reduced.

The fluorinated copolymer used in the present invention has excellent mechanical properties, and is usually 30 to 60 kPa more than a copolymer having the same composition and the same specific melt viscosity produced by a conventional method.
It has a high g / cm ² tensile strength at break, and it can be said that the present invention is also excellent in this respect.

Therefore, when the fluorine-containing copolymer molded article of the present invention is used in a piping system such as a wafer carrier, a bottle or a tube in a semiconductor manufacturing process, the amount of generated particles is small, and a highly integrated LSI is manufactured. Not only is it effective in the production of, but it can also be used in industrial fields where properties as fluororesins such as chemical resistance, heat resistance and electrical properties are required as a fluorine-containing copolymer having improved mechanical strength.

[0053]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.

The measured values were obtained as follows.

1. a. Measurement of tensile breaking strength Based on JIS K-7113.

B. Preparation of Test Sample The fluorinated copolymer of the present invention and a resin for comparison were 35
By melting at a temperature of 0 ° C. and cooling under pressure, 1
A sheet having a thickness of mm was prepared, and test pieces required for the test method were prepared.

[0057] 2. Measurement of Specific Melt Viscosity A Koka type flow tester was used. Diameter 1mm, length 10
2. Measured at a temperature of 372 ° C. with a load of 13.14 kg using a mm die. a. Particle measurement After repeatedly washing the test piece with high-purity isopropyl alcohol and ultrapure water and drying naturally in a clean room,
It was immersed in 500 g of a high-purity 50% hydrofluoric acid solution and the change with time in the number of particles was measured. The measurement was carried out using a particle counter KL-22 (manufactured by Rion Co.),
The number of μm particles was counted.

B. Preparation of Test Sample The fluorinated copolymer of the present invention and a resin for comparison were 35
By melting at a temperature of 0 ° C. and cooling under pressure, 1
A sheet having a thickness of mm was prepared and cut out to a size of 50 mm × 70 mm to prepare a test piece required for the above test.

Example 1 45 kg of chlorofluorocarbon-113, which had been purified by distillation, was placed in a stainless steel 75 L reactor having a stirrer.
The inside was degassed, and then the pressure was increased to atmospheric pressure with nitrogen gas. After charging 6.0 g of methanol and 320 g of 2,2,3,3,3-pentafluoropropyltrifluorovinyl ether into the reactor, the rotation speed of the stirring motor was set to 140, tetrafluoroethylene was introduced, and the pressure was increased to 4. 0.2 kg / cm ²
-G. Next, while maintaining the inside of the reactor at 18 ° C. (C ₃
F ₇ CO _{2) 2} CFC -113 solution (5wt%) 55.
3 g was introduced to initiate polymerization. 2.6kg reactor pressure
/ Cm ² -G, methanol 850 when the concentration of the produced fluorocopolymer becomes 4.4% by weight in the reaction solution.
g was added to terminate the polymerization. Next, after releasing the unreacted tetrafluoroethylene in the reactor, the reaction solution is transferred to a 100 L polymer precipitation tank having a stirrer, and the polymerization solvent and unreacted monomer are distilled out by heating the polymer precipitation tank to contain the polymer. A fluorine copolymer was obtained. The copolymer was vacuum-dried at 150 ° C. for 12 hours to obtain 2 kg of the copolymer.

This fluorinated copolymer was formed into a film at 330 ° C., and the IR was measured. The result is shown in FIG. FIG.
In, 950 cm around ^-1> CFOCH ₂ - -CH ₂ near groups and 2900 cm ^-1 - absorption band based on the group is confirmed, in the fluorocopolymer 2,2,3,3,3-pentafluoro It was found that 2.8 mol% of a monomer unit based on propyltrifluorovinyl ether was contained. The polymer was melt-molded and the tensile strength at break was measured in accordance with JIS K-7113.
cm ² . The specific melt viscosity at 372 ° C. is 1.
It was 5 × 10 ⁵ poise.

Further, 1 kg of this polymer was placed in a 3 L autoclave, and Freon-113 and Freon-14 were added.
Using 1 L of each 1b, extraction was performed at 80 ° C. for 18 hours. After separating the copolymer and the solvent by filtration, the copolymer was dried under reduced pressure at 150 ° C. for 12 hours. At this time, the weight loss of the copolymer was 0.004% by weight of CFC-113,
0.004% by weight of Freon-141b. Also,
When the Freon-113 used for the extraction was concentrated,
4 g of a white substance were obtained.

Comparative Example 1 After the reactor pressure reached 2.6 kg / cm ² , the reaction was carried out in the same manner as in Example 1 except that the unreacted monomer and the solvent were distilled off without adding methanol. . As a result of the analysis, the obtained copolymer contained 2.8 mol% of a monomer unit based on 2,2,3,3,3-pentafluoropropyltrifluorovinyl ether. The tensile strength at break is 380 kg / cm ² and the specific melt viscosity is 1.4 × 10 ^5.
It was poise, and the weight loss after extraction with Freon-113 as in Example 1 was 0.05% by weight.

Further, when the copolymer extracted with Freon-113 was again extracted with Freon-113, the weight loss was 0.025% by weight. The weight loss due to the extraction of this copolymer with Freon-141b was 0.05%.
% By weight.

Example 2 70 kg of Freon-113 previously purified by distillation was placed in a stainless steel 75 L reactor having a stirrer.
The inside was degassed, and then the pressure was increased to atmospheric pressure with nitrogen gas. After 37 g of methanol and 6.2 kg of perfluoropropyl vinyl ether were put in the autoclave, the rotation speed of the stirring motor was set to 140, tetrafluoroethylene was introduced, and the pressure was adjusted to 6 kg / cm ² -G. Then, while maintaining the inside of the reactor at 18 ° C., the CFCs of (C ₃ F ₇ CO ₂ ) ₂
180 g of 113 solution (5 wt%) was introduced to initiate polymerization. Tetrafluoroethylene was continuously supplied so that the reactor pressure was maintained at 6 kg / cm ² -G. When the supply amount of tetrafluoroethylene was 3.9 kg, and the concentration of the produced fluorine-containing copolymer became 6.7% by weight in the reaction solution, the reaction solution was put into a 100 L polymer precipitation tank having a stirrer containing 1 kg of methanol. To stop the polymerization.
Next, by heating the polymer precipitation tank, the solvent and unreacted monomer were distilled off to obtain a copolymer.

As a result of IR measurement,> C was found around 990 cm ^−1.
Absorption bands based on the FOCF ₂ — group and the —CF ₂ — group were confirmed at around 1200 cm ⁻¹ , and the content of monomer units based on perfluoropropylvinyl ether in this copolymer was 1.3 mol%. I understood. Moreover, tensile strength was 410 kg / cm ^2, specific melt viscosity at 372 ° C. is 8.0 × 10 ⁴ poise, 80 ° C., 18 hours
, The weight loss after extraction with Freon-113 and Freon-141b was 0.007% by weight and 0.008%, respectively.
% By weight.

Comparative Example 2 A reaction was carried out in the same manner as in Example 2 except that methanol was not added to the polymer precipitation tank. As a result of analysis, the copolymer contained 1.3 mol% of monomer units based on perfluoropropyl vinyl ether, had a specific melt viscosity at 372 ° C. of 6.7 × 10 ⁴ poise, and had a tensile strength of 6.7 × 10 ⁴ poise. Breaking strength is 3
The weight loss after extraction with 70 kg / cm ² and CFC-113 was 0.06% by weight.

Example 3 The copolymer obtained by extracting the fluorinated copolymers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 with Freon-113 was treated with 50%.
% Hydrofluoric acid, 0.3 to 2 in 1 cc hydrofluoric acid solution
The number of μm particles was measured 6, 9, and 14 days after the start of immersion. The results are shown in Table 1.

[0068]

[Table 1]

Example 4 After placing 45 kg of Freon-113 purified by distillation in a stainless steel 75 L reactor having a stirrer,
The inside was degassed and then 9 mol% of 2,2
A mixed gas of 2,2-trifluoroethyl trifluorovinyl ether and 91 mol% of tetrafluoroethylene was introduced into the reactor, and the pressure was adjusted to the atmospheric pressure. Methanol 24 in the reactor
g, the rotation speed of the stirring motor was set to 140, and the mixed gas was introduced to 4.0 kg / cm ² -G. Next, while maintaining the inside of the reactor at 22 ° C. (C ₂ F ₅ CO
₂ ) 90 g of a Freon-113 solution of ₂ (5 wt%) was introduced to initiate polymerization. During the reaction, the mixed gas was continuously introduced to maintain 4.0 kg / cm ² -G. When the amount of the mixed gas introduced is 3.0 kg and the concentration of the produced fluorine-containing copolymer becomes 6.7% by weight in the reaction solution, hexane 1k is used.
g was added to terminate the polymerization, and a copolymer was obtained in the same manner as in Example 1.

As a result of IR measurement, as in Example 1, 95
Around 0 cm ^-1 > CFOCH ₂ -group and 2900 cm
-CH ₂ around ^-1 - observed absorption band based on the group, the monomer unit based on 2,2,2-trifluoroethyl trifluoromethyl ether contained in the copolymer is met 8.8 mol% Was. The specific melt viscosity is 8.0 × 10 ³ poise, tensile strength was 330 kg / cm ^2, 80
As a result of extraction with Freon-113 at 18 ° C. for 18 hours , the weight loss was 0.005% by weight.

Example 5 21 kg of ion-exchanged water, 15 kg of perfluorotributylamine previously purified by distillation, and 100 g of C ₇ F ₁₅ CO ₂ NH _{4 in} a stainless steel 75 L reactor having a stirrer
And then degassing the inside, and then a mixed gas of 3 mol% of 2,2,3,3,3-pentafluoropropyl trifluorovinyl ether prepared in advance and 97 mol% of tetrafluoroethylene Was introduced into the reactor to atmospheric pressure. After 5 kg of ethanol was put into the reactor, the rotation speed of the stirring motor was set to 140, and the mixed gas was introduced to 4.0 k
g / cm ² -G. Then, while keeping the inside of the reactor at 18 ° C., 250 g of (ClCF ₂ CF ₂ CO ₂ ) ₂ perfluorotributylamine solution (5 wt%) was introduced to initiate polymerization. During the reaction, the above mixed gas was continuously introduced, and 4.0 kg
/ Cm ² -G was maintained. The amount of the mixed gas introduced is 2.
When 5 kg of the produced fluorine-containing copolymer had a concentration of 6.9% by weight in the reaction solution, 1 kg of chloroform was added to stop the polymerization, and then a copolymer was obtained in the same manner as in Example 1. .

As a result of IR measurement, as in Example 1, 95
Around 0 cm ^-1 > CFOCH ₂ -group and 2900 cm
-CH ₂ around ^-1 - absorption band based on group was observed, the monomer unit based on 2,2,3,3,3-pentafluoro-propyl trifluoromethyl ether contained in the copolymer is 2.8
Mole%. The specific melt viscosity was 3.2 × 10 ⁵ poise, the tensile strength at break was 460 kg / cm ² , and the weight loss was 0.003% by weight as a result of extraction with Freon-113 at 80 ° C. for 18 hours. Was.

Example 6 Using the same method as in Examples 1 and 2, various fluorine-containing vinyl ethers were reacted with tetrafluoroethylene to obtain a fluorine-containing copolymer. The type of the fluorinated vinyl ether used, the polymerization terminator, the content of the monomer unit based on the fluorinated vinyl ether contained in the obtained copolymer, the specific melt viscosity of the obtained copolymer, and the tensile rupture Table 2 shows the strength, the weight loss by extraction with Freon-113, and the number of particles after immersion in 50% hydrofluoric acid for 14 days.
It was shown to. The extraction with Freon-113 was performed at 80 ° C.
For 18 hours.

[0074] IR result of the measurement, like the copolymer also Example 1 of Izure, around 950cm ^-1> CFOCH ₂ - absorption band based on group was observed - -CH ₂ near groups and 2900 cm ^-1 .

[0075]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a chart of an infrared absorption spectrum of a fluorine-containing copolymer used in the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-276808 (JP, A) JP-A-3-250008 (JP, A) JP-A-3-247609 (JP, A) JP-A-62- 104822 (JP, A) JP-A-58-191127 (JP, A) JP-A-61-98709 (JP, A) JP-A-1-72182 (JP, A) JP-A-62-285907 (JP, A) JP-A-4-20507 (JP, A) JP-A-63-128054 (JP, A) JP-A-62-230804 (JP, A) JP-A-50-103553 (JP, A) JP-A-49-119921 (JP, A) JP-B 51-25398 (JP, B1) JP-B 48-2223 (JP, B1) JP-B 48-20788 (JP, B1) (58) Fields investigated (Int. Cl. ⁶⁾ , DB name) C08F 214/00-214/28 C08F 14/00-14/28 C08F 2/00-2/60 C08F 6/00-6/28

Claims (3)

(57) [Claims] 1. A general formula _{(I) - (CF 2 CF} 2) - monomer unit 90 to 99.5 mol% and the formula is based on (I) (II) ## STR1 ## (Where Rf is a halogenated hydrocarbon group) consisting of 10 to 0.5 mol% of a monomer unit represented by the following formula:
Having a specific melt viscosity of 10 ² to 10 ⁷ poise as measured in the above, and a weight loss after extraction with a fluorinated organic solvent at 80 ° C. for 18 hours of not more than 0.01% by weight. Moldings. 2. A monomer unit based on the general formula (I)-(CF ₂ CF ₂ )-(I) of at least 60 mol% and less than 90 mol% and a compound of the general formula (II) (Where Rf is a halogenated hydrocarbon group) consisting of more than 10 mol% and less than 40 mol% of a monomer unit represented by the following formula, and having a specific melt viscosity of 10 ² to 10 ⁷ poise measured at 200 ° C. After extraction with a fluorine-containing organic solvent at 80 ° C for 18 hours
A molded article of a fluorine-containing copolymer, characterized in that the weight loss is 0.01% by weight or less . (3) tetrafluoroethylene and the following general formula (II)
_{I) CF 2 = CFORf (III} ) ( where, Rf is obtained by copolymerizing fluorine-containing vinyl ether represented by the halogenated hydrocarbon group.), Non remaining
The method for producing a fluorine-containing copolymer for molded articles according to claim 1 or 2, wherein the unreacted monomer is removed after adding a polymerization terminator of 20 mol% or more based on the reactive monomer.