JPS63238115A - Production of fluorine-containing copolymer having cyclic structure - Google Patents

Abstract

PURPOSE:To suppress secondary occurrence of gelation without adopting an ultrahigh pressure or high dilution condition and smoothly, industrially and advantageously obtain the titled copolymer, by radically polymerizing a specific perfluoro ether with other monomers. CONSTITUTION:A perfluoro ether, expressed by the formula (m and n are 0-5 and m+n is 1-6) and having two terminal double bonds is copolymerized with other radically copolymerizable monomers to afford the aimed copolymer. Furthermore, perfluoroallyl vinyl ether is preferably used as the perfluoro ether expressed by the formula. A fluorine-containing monomer, such as tetrafluoroethylene, is preferably used as the other monomers.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing a fluorine-containing copolymer having a cyclic structure, and more specifically, the present invention relates to a method for producing a fluorine-containing copolymer having a cyclic structure. This invention relates to a new method for producing a fluorine-containing copolymer having a ring structure in the copolymer main chain, which comprises radical copolymerization of an ether and another comonomer.

[Prior Art] Various fluorine-containing copolymers have been known so far, and CF2 J:F2/CF2=CFORf is a copolymer of fluorine-containing olefins and fluorine-containing vinyl ethers.
, CF2-CF2/ CH2-CH2, CF2-IC
F2/ CF2=CFCF3, CF2寞CFCI
/ There are many products that are used industrially, such as the CH21lCH2 system, but most of these are based on copolymerization reactions with fluoroolefins, hydrocarbon olefins, or vinyl monomers that have a fluoroalkyl group in the side chain. It is a copolymer with a linear main chain.

Alternatively, high molecular compounds such as perfluoropolyether obtained by ring-opening polymerization of hexafluoropropylene oxide are also known, but in this case as well, the main chain structure is linear, and the application to copolymerization is also known. is also difficult.

Attempts have been made to synthesize a polymer having a ring-opened metathesis, a cyclic structure in the main chain, using a molybdenum-based catalyst (A, Alimuniar at al, Polym
Er.

1988271281), these are all ordinary vinyl polymerization, ring opening, ring opening metathesis polymerization,
A ring structure is not introduced into the main chain by ring-closing polymerization from a linear monomer.

Slightly, general formula CF2-CF4Ch*xCF-CF2
(X is 1 to 5) is known to be cyclized and polymerized by γ-rays (L, A, Waal, Flu
or.

Polymer, Wiley-Science, 4
．． High Pressure Polymeriza
tion, P, 127), and CF2 = CF-C
It is known that F2-CFCI-CF2-CF=CF2 polymerizes to give a transparent, strong elastic film with excellent heat resistance and oxidation resistance (D, S, Balenti
ne etal,, U, S, Atomic Ener
gy Com5. B, ML-294 (T-50)18.
1954), but these are all 10,000 a
This is a high-pressure polymerization method that requires a high pressure of tm or higher, and has the disadvantage that it is difficult to implement industrially, and there are no examples of its application to copolymerization reactions.

Furthermore, British Patent No. 11013344, U.S. Patent No. 3
No. 418302 Natoni is CF2-cF-o-cF2-
A method is described in which perfluorodimethylene bis(perfluorovinyl ether), CF2-0-CF-CF2, is cyclized or copolymerized with a fluoroolefin or fluorovinyl ether as a monomer. However, this polymerization method has a restriction that cyclization polymerization can only be carried out under diluted conditions where the specific divinyl ether monomer concentration is 12% by weight or less. It is stated that when the monomer concentration is 12% or more, a polymer is produced. The monomer concentration must be 12% or less, which is disadvantageous for industrial implementation because there is a limit to the ratio of ring structure introduction into the main chain and a large amount of diluting solvent must be used. .

[Problems to be Solved by the Invention] According to the research of the present inventors, regarding fluorine-containing copolymers, particularly perfluoro copolymers, it is possible to convert copolymers having a ring structure in the main chain from linear monomers. As mentioned above, there is almost no known means for industrially producing it smoothly and advantageously, and there is also a ring method using a heptamine such as the perfluorodimethylene bis(perfluorovinyl ether) mentioned above. In chemical polymerization, in addition to the limitation of polymerization under conditions of large dilution as described above, there is a drawback that gelation is a by-product in the polymerization reaction system.

Based on the recognition of the above-mentioned problems, the present inventor conducted extensive research on the production of fluorine-containing copolymers having a ring structure in the main chain.
As a result of repeated studies, we found that by radical copolymerization using specific monomers such as perfluoroallyl vinyl ether, it was surprisingly possible to eliminate gelation by-products without using ultra-high pressure conditions or large dilution conditions. It has been found that the desired fluorine-containing copolymer can be produced smoothly and advantageously.

[Means for Solving the Problems] Thus, the present invention has been completed based on the above-mentioned new findings, and has the general formula CFzlICF(CF2)n
o(CF2)scF==cF2 (where n is 0 to 5,
The perfluoroether having two terminal double bonds represented by 0 to 5 (layers are 0 to 5, and n+m is 1 to 6) is radically copolymerized with other monomers capable of radical copolymerization. The present invention provides a novel method for producing a fluorine-containing copolymer having a cyclic structure, which is characterized by producing a copolymer having a cyclic structure in its main chain.

In the present invention, it is important to use specific perfluoroethers, for example CF2 snow CF-0-C
By radical copolymerizing F2-CF-CF2 with CF2-CF2 or the like, a fluorine-containing copolymer can be produced smoothly and advantageously.

n and m in the above general formula are each an integer of 0 to 5,
1+11 is an integer selected from a combination of 1 to 6. Preferably, n and m are each integers of 0 to 3,
n+m is 1 to 4, more preferably n and m are each θ
An integer of ~2 and n+ra of 1 to 3 is adopted.

The above specific perfluoroether is perfluoroallyl vinyl ether CCF2=CFOCF2CF
-CF2), par7le:tel diallyl vinyl ether (CF21=CFCF20CF2CF-CF2)
, perfluorobutenyl vinyl ether (C:F2-
CFOCF2 CF2CF-CF2), perfluorobutenyl allyl vinyl ether)1. yCCF2-CFC
F20ChCF2CF-CF2), perfluorodibutenyl vinyl ether (CF2-CFCF2CF20CF
2CF2 CF -CF2 ), etc., but in the present invention, one in which either n or ++ is 0,
That is, those having one vinyl ether group such as CF2=CFO- are preferably employed in terms of copolymerization reactivity, ring-closing polymerization, and gelation suppression, and in particular, perfluoroallyl vinyl ether (CF2-111: FOCF2 CF=
CF2) is mentioned as a suitable example.

Other monomers to be copolymerized with the above-mentioned specific perfluoroether are not particularly limited as long as they are radically polymerizable monomers, and a wide range of examples include fluorine-containing monomers, hydrocarbon monomers, and others. obtain. Of course, these other monomers may be used alone in radical copolymerization with the specific perfluoroether, or two or more appropriate types may be used in combination to carry out the above copolymerization reaction. 0 In the present invention, in order to make the most of the properties of the specific perfluoroether, it is usually desirable to select fluorine-containing monomers such as fluoroolefins and fluorovinyl ethers as other monomers. Fluoroethylene, perfluorovinyl ether, etc. are preferred specific examples, and vinylidene fluoride, vinyl fluoride, chlorotrifluoroethylene, etc. may also be exemplified.

The surprising fact was discovered that the specific perfluoroether and other monomers copolymerize under relatively mild conditions to give a copolymer having a cyclic structure in the main chain, which led to the present invention. It is something that That is, the polymerization method is not particularly limited as long as it proceeds in a radical manner, and examples thereof include polymerization using an organic or inorganic radical initiator, light, ionizing radiation, or heat. As the radical initiator, 2,2'-azobis(N,N'-dimethyleneisobutyramidine) dihydrochloride, 2
．． 2'-azobis(2-amidinopropane) dihydrochloride, 2.2'-azobis(N,N'-dimethyleneinbutyramidine), 4.4'-azobis(4
-cyanopentanoic acid), 2,2'-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide)
, 2.2'-azobis(2-methyl-N-[1,1
-bis(hydroxymethyl)ethyl]propionamide), 2,2'-azobis[2-methyl-N-(2-
hydroxyethyl)propionamide], 2.2'
-Azobis(inbutyramide)cybiderate, 2,
2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), (1-phenylethyl)azodiphenylmethane, 2,2'-azobis isobutyronitrile,
Dimethyl 2.2'-azobisisobutyrate, 2.2'
-azobis(2-methylbutyronitrile), 1.1
'-azobis(1-cyclohexanecarbonitrile),
2-(carbamoylazo)-isobutyronitrile, 2,
2'-azobis(2,4,4-)limethylpebutano),
Azo compounds such as 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2,2'-azobis(2-methylpropane), stearoyl peroxide, diisopropyl peroxydicarbonate, benzoyl peroxide, 2.4 -dichlorobenzoyl peroxide, acetyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, di-isopropylbenzene hydroperoxide, para-menthane hydroperoxide, 2,5-dimethylhexane-2,5-
Cibidroba-oxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-
butylperoxy)hexane, 2,5-dimethyl-2,
5-di(1-butylperoxy)hexyne-3, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, t-
Butyl peracetate, t-butyl perpivalate, t
-Butylperyne butyrate, t-butylperoxyisobrobyl carbonate, di-t-butylshiba-phthalate, t-butylperlaurate, 2.5-dimethyl-
Organic peroxides such as 2,5-di(benzoylperoxy)hexane, diperfluorobutanoic peroxide, diperfluoro-3-oxa-2-methylhexanoic peroxide, diperfluorononanoic peroxide , K2 S20s.

Examples include inorganic peroxides such as 20 g of (NH4) 2 S. Examples of the light include visible light and ultraviolet light, and a photosensitizer can also be used in combination. Ionizing radiation is 60 (: (1, +92ir, 1707z, 13
Examples include γ rays, β rays, α rays, etc. from radioactive isotopes such as 70S, and electron beams from an electron beam accelerator.

The polymerization method is also not particularly limited, and includes so-called bulk polymerization in which the monomer is directly subjected to polymerization, and fluorinated hydrocarbons, chlorinated hydrocarbons, fluorochlorinated hydrocarbons, alcohols, hydrocarbons, and other organic solvents in which the monomers are dissolved. Examples include solution polymerization carried out in an aqueous medium, suspension polymerization carried out in the presence or absence of an appropriate organic solvent in an aqueous medium, and emulsion polymerization carried out by adding an emulsifier to an aqueous medium. Although not particularly limited,
It is desirable to set the temperature appropriately in consideration of various factors such as the boiling point of the monomer, the required heat source 1, and the removal of the heat of polymerization. For example, 0°C.
A suitable temperature can be set between 200°C and 200°C, and a practically suitable temperature can be set between room temperature and 100°C. In addition, the polymerization pressure may be under reduced pressure or increased pressure, and practically, it is about normal pressure to 100 atmospheres,
Furthermore, suitable polymerization can be carried out at normal pressure to about 50 atmospheres.

In the present invention, there is no particular reason to limit the copolymerization ratio of the above-mentioned specific perfluoroether, but from the viewpoint of introducing a ring structure into the main chain to improve various performances as described below, it is usually It is used in an amount of 0.1 mol% or more in the charging composition with respect to other monomers.

A feature of the copolymer obtained by the present invention is that, for example, when copolymerized with CF2-0F2, the crystallinity can be lowered compared to polytetrafluoroethylene (hereinafter abbreviated as PTFE). Therefore, this copolymer can be melt-molded and has improved transparency. Furthermore, when the composition of the annular portion is increased, it becomes meltable and can be cast into a film. In other words, since the obtained copolymer with tetrafluoroethylene is easier to mold than PTFE, it can be used for various molded products having the same performance as PTFE as a fluororesin. Furthermore, it can be used for various coating materials, electronic components, optical components, etc. that utilize transparency and cast film formation methods.

When copolymerized with CF2-GH2, compared to vinylidene fluoride homopolymer (hereinafter abbreviated as PVdF), crystallinity is lowered, crystal grain size is reduced, and transparency is improved. It is also possible to lower the refractive index, which is one of the characteristics of PVdF.
The fluorine content can be increased without compromising the already high strength properties of the copolymer. Therefore, this copolymer can be applied in all fields where PVdF is currently used.
In particular, it is suitable for hanging threads because it lowers the refractive index and improves transparency. Furthermore, it can also be used as a transparent dielectric material in electronic components and optical components. Furthermore, since it can be melt-molded and cast and has a high fluorine content, it is possible to provide various molded bodies and various coating materials that have better weather resistance, solvent resistance, heat resistance, and chemical stability than PVdF.

As mentioned above, when a conventionally known fluorine-containing monomer and a specific perfluoroether monomer are copolymerized,
It is possible to lower the crystallinity and reduce the crystal grain size, improving transparency and making melt molding possible. In addition, mechanical strength such as elastic modulus is also increased. Furthermore, when the perfluoroether composition is increased, it becomes soluble in solvents, and the disadvantages of fluorine-containing polymers such as opacity, moldability, and mechanical strength can be improved.

When copolymerized with a hydrocarbon-based monomer, this copolymer has a higher property ladder as a hydrocarbon-based polymer than a hydrocarbon-based or fluorine-containing copolymer such as PTFE or PVdF. It is possible to impart the characteristics of a fluoropolymer without lowering the properties. The reason for this is not clear.

This is thought to be because the fluorine moiety exhibits a cyclic structure and does not form crystals.

In addition, since the fluorine-containing copolymer obtained by the present invention has a fluorine-containing cyclic structure, it has high gas separation performance and can be used as a material for gas separation membranes.

[Function] In the present invention, the mechanism by which use of a specific perfluoroether eliminates the need for ultra-high pressure conditions or high dilution conditions for cyclization polymerization is not necessarily clear, but C
Since the -0-C bond is flexible, it is thought that the two double bonds can easily approach each other within the molecule, allowing cyclopolymerization to proceed even under low pressure. It is thought that this makes it easier to cause some kind of difference in the reactivity of the two double bonds, thereby suppressing gelation as a by-product during the copolymerization reaction without adopting high dilution conditions. It should be noted that this explanation is provided to assist in understanding the present invention, and is not intended to limit the present invention in any way.

[Examples] 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.

Example 1 5 g of perfluoroallyl vinyl ether, 15 g of trichlorotrifluoropentathane (hereinafter abbreviated as R-113), and a polymerization initiator ((3F7 Co)
80 mg of 25 wt% R-113 solution was placed in a pressure-resistant glass ampoule for 10 h (2). After repeating freezing and degassing three times, 0.5 g of CF2-CF2 was charged and incubated at 30°C with shaking in an incubator for 6 hours. As a result of time polymerization, 1.5 g of solid was obtained.

The obtained solid was dissolved in perfluorobenzene, and the structure was confirmed by 19F NMR spectrum. As a result, it was found that the obtained polymer was a copolymer of a cyclic structural unit such as the following and a tetrafluoroethylene unit, and the a/b molar ratio was 110.52. Moreover, the intrinsic viscosity of this copolymer is 0
．． It was 425.

Example 2 5g of perfluoroallyl vinyl ether, 15g of R-113 and 25g of polymerization initiator (C3F7GO)
50+sg of wt% R-113 solution was added to 100s12 (
7) Placed in a pressure-resistant glass ampoule. After repeating freezing and degassing three times, 0.5g of CF2-CF2 was charged, 3
As a result of polymerization at 0° C. for 45 minutes, 1.8 g of white powder was obtained. The obtained solid was found to be the same copolymer as in Example 1 from the 19F NMR spectrum.

Example 3 5 g of perfluoroallyl vinyl ether, 25 g of pure water
3. 0.09g of CBF+7G02M)In, Ha)
12 0.073 g of PCla and 0.0132 g of ammonium sulfate were placed in a pressure-resistant glass ampoule of 100+ m (2). After replacing the system with nitrogen gas sufficiently, CF
0.5 g of 2-CF2 was charged and polymerization was carried out at 60° C. for 18 hours with shaking in an incubator, resulting in 2.5 g of solid.

The obtained solid was dissolved in perfluorobenzene and +91i
The structure was confirmed by NMR spectrum. Moreover, the intrinsic viscosity of this copolymer was 0.30.

Example 4 20 g of perfluoroallyl vinyl ether, R-11
80 g of No. 3 and 20+ wg of polymerization initiator diisopropyl peroxydicarbonate were placed in a 20 m (20 m) pressure-resistant glass ampoule.
was charged and polymerization was carried out for 4 hours and 30 minutes under the same conditions. As a result, 12.3 g of acetone-soluble solid was obtained.

Example 5 5 g of perfluoroallyl vinyl ether, 8.74 g of perfluoropropyl perfluorovinyl ether, and 5 g of 2.2'-azobisisobutyronitrile were mixed into 10
The 0+Q liquor was placed in a glass ampule. After repeating freezing and degassing three times, polymerization was carried out at 60° C. for 18 hours while shaking in an incubator, resulting in 0.9 g of solid.

[Effects of the Invention] The present invention provides an excellent advantage in that a fluorine-containing copolymer having a ring structure in the main chain of the copolymer can be produced smoothly and advantageously by employing a specific perfluoroether as a copolymerization component. have an effect.

In particular, the introduction of a ring structure into the main chain is achieved without employing ultra-high pressure conditions or high dilution conditions, and the presence of one ether bond suppresses gelation as a by-product during the polymerization reaction. This effect is also recognized. Furthermore, in the present invention,
Since a fluorine-containing ring structure can be introduced into the main chain of various polymers, it is possible to impart various excellent and useful properties to the resulting fluorine-containing copolymers.For example, PTF
By applying it to other fluorine-containing polymers, it can provide useful properties such as non-caking property, transparency, and solvent solubility without impairing the heat resistance, chemical stability, electrical properties, etc. of the original fluorine-containing polymer. It is possible to provide an ultra-thin film.

Claims (1)

[Claims] 1. General formula CF_2=CF-(CF_2)-_nO-(
CF_2) -_mCF=CF_2 (where n is 0 to 5
, m is 0 to 5, and n+m is 1 to 6), and another radically copolymerizable monomer is radically copolymerized to form a copolymer. 1. A method for producing a fluorine-containing copolymer having a cyclic structure, which comprises producing a copolymer having a cyclic structure in the polymer main chain. 2. Perfluoroether is CF_2=CF-O-CF
_2-CF=CF_2 perfluoroallyl vinyl ether, the manufacturing method according to claim 1. 3. The production method according to claim 1 or 2, wherein the perfluoroether is charged to the copolymerization reaction system in an amount of 0.1 mol % or more based on other monomers.