JPH0780977B2 - Chlorotrifluoroethylene copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to chlorotrifluoroethylene such as a chlorotrifluoroethylene / perfluoro (2-methylene-4-methyl-1,3-dioxolane) copolymer. The present invention relates to a system copolymer.

[Prior Art] Conventionally, perfluoro (2-methylene-4-methyl-1,3
-Dioxolane) and perfluoro (2-methylene-4-methyl-1,3-dioxolane) -tetrafluoroethylene copolymers are known (US Pat.
3,307,330, 3,308,107). These (co) polymers are said to be excellent as a separation membrane material for separating a gas such as helium or hydrogen and a gas such as nitrogen or methane having a large molecular diameter. However, these (co) polymers have the drawback of poor solubility. For example, polyperfluoro (2-methylene-4-methyl-1,3-dioxolane) is described in the patent specification as being soluble in perfluoro (2-butyltetrahydrofuran) or perfluorodimethylcyclobutane, but at room temperature Fluoro (2-methylene-4-methyl-1,3-dioxolane)
Has a drawback that it has almost no solubility in perfluoro (2-butyltetrahydrofuran). The polymer could only be eluted using Soxhlet, but the drawback was that the solution was not homogeneous. Further, the solvent in which the polymer is said to be soluble in the above-mentioned specification is perfluoro (2-butyltetrahydrofuran) or hexafluorodichlorobutene-2 or perfluorodimethylcyclobutane, and these solvents are limited to a special type. It has the drawback of being a solvent. Further, the specification of the patent describes the performance of a press film of polyperfluoro (2-methylene-4-methyl-1,3-dioxolane) and a cast film obtained by evaporating a solvent, The helium permeability coefficient of the membrane is only 1.44 times that of the pressed membrane, and the hydrogen / methane permeability coefficient ratio is only 1/6 or less. Originally, the permeation coefficient and the permeation coefficient ratio of materials should be substantially the same for the same material, but the difference is such that polyperfluoro (2-methylene-4-methyl-1,3-dioxolane) It is thought that this is due to the poor solubility of the. Poor permeation performance of the cast membrane is a major drawback as a separation membrane material in view of the fact that casting is easier than pressing to obtain a thin membrane because it is a composite membrane.

[Problems to be Solved by the Invention] The present invention has been found as a result of various studies based on the recognition of the above-mentioned problems, and was found to be a hitherto unknown chlorotrifluoroethylene and perfluoro (2-methylene- Four
-Methyl-1,3-dioxolane), in which the content of the constitutional unit in which chlorotrifluoroethylene is polymerized is 10 to 90 mol% is newly provided. In other words, this copolymer is a copolymer that is unique in its chemical and physical properties, and it is a fluorine-based copolymer with particularly excellent gas permeability coefficient and permeability coefficient ratio and high chemical stability. Although it is a polymer,
The good workability obtained from the property of being soluble in a general-purpose solvent shows the versatility of the present copolymer.
Specific application fields showing the usefulness of this copolymer include:
Examples thereof include coating materials, coating materials, insulating film materials, weather resistant film materials, and separation membrane materials. Especially as a material for separation membranes, high helium, hydrogen, carbon dioxide and oxygen permeability and high helium /
It is an excellent material that combines nitrogen, helium / methane, hydrogen / carbon monoxide, hydrogen / nitrogen, hydrogen / methane, carbon dioxide / methane and oxygen / nitrogen permeation coefficient ratios, and is capable of reducing the film thickness. is there.

[Means for Solving Problems] The present invention has been completed based on the above-mentioned findings, and comprises chlorotrifluoroethylene-polymerized structural unit (A) and perfluoro (2-methylene-4-methyl-). 1,3-dioxolane) is a copolymer having a number average molecular weight of 3,000 or more consisting of a structural unit (B) polymerized, and the content of the structural unit (A) in the copolymer is 10 to 90 mol%. Is a chlorotrifluoroethylene copolymer.

Hereinafter, the present invention will be described more specifically.

The structure of this copolymer may vary depending on the content ratio of constituent monomers, molecular weight, etc., but essentially contains a chlorotrifluoroethylene unit and a perfluoro (2-methylene-4-methyl-1,3-dioxolane) unit. Is essential. As the content ratio of the constituent monomer, it is essential that the content ratio of the constituent unit (A) obtained by polymerizing chlorotrifluoroethylene in the copolymer is 10 to 90 mol%. In order to sufficiently make the contribution of each component, the content rate in the copolymer of the structural unit (A) in which chlorotrifluoroethylene is polymerized is
It is desirable to be 20 to 80%, preferably 25 to 75%.
Structural unit (A) in which chlorotrifluoroethylene is polymerized
If the content in the copolymer is too low, it is not desirable from the viewpoint of solubility. Further, if the content of the structural unit (A) in which chlorotrifluoroethylene is polymerized in the copolymer is too high, it becomes a polymer having high crystallinity, the solubility is lost, and the gas permeability coefficient is low, which is not preferable. It is also possible to copolymerize a specific third or more component, if necessary, whereby, for example, gas permeability, crosslinkability, substrate adhesion, etc. can be imparted. In order not to lose the characteristics of the polymer, chlorotrifluoroethylene-polymerized structural unit (A) and perfluoro (2-
Methylene-4-methyl-1,3-dioxolane) -containing structural unit (B) in the copolymer, the total content of which is 90 mol% or more, and other comonomer is contained in the structural unit. Is 10
It is desirable that the content is mol% or less. Other comonomers introduced for this purpose include perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, perfluoropropyl vinyl ether, and perfluoro (3,6-
Dioxa-5-methyl-nonene-1), fluorovinyl ethers such as perfluorobromoethyl vinyl ether, fluoroolefins such as bromotrifluoroethylene, vinyl esters such as vinyl acetate, vinyl benzoate, vinyl butyrate, ethylene, propylene , Α-olefins such as isobutylene, vinyl ethers such as ethyl vinyl ether, butyl vinyl ether and hydroxyalkyl vinyl ether.

Particularly, the general formula: CF ₂ = CFORfa-O _n Rfb, where Rfa is -CF ₂ CXY- Rfb is CF _{2 m} CXYZ n is 0 to 3 m is 0 to 3 (X, Y is F or CF ₃ ) (Z is Vinyl ethers represented by H, Br, Cl, F or CF ₃ ) are preferable because they have good copolymerizability and do not impair chemical stability and gas permeability.

The molecular weight of the copolymer is not particularly limited as long as it has a number average molecular weight of 3,000 or more because the preferred range varies depending on the application, but generally, a polymer having a too small number average molecular weight is not desirable. Particularly, about 5,000 or more is preferably used for various purposes.

Perfluoro (2-methylene-4-) used in the present invention
Methyl-1,3-dioxolane) can be synthesized by the method described in US Pat. No. 3,307,330.

The copolymer of the present invention is a conventionally known or well-known polymerization method, for example, solution polymerization, suspension polymerization, emulsion polymerization,
It can be smoothly and advantageously manufactured without any particular limitation.

Examples of the radical initiator that can be used in the solution polymerization include di (chlorofluoroacyl) peroxide, di (perfluoroacyl) peroxide and di (ω-hydroperfluoroacyl) peroxide described in JP-B-47-44031. Oxide, di (chlorofluoroacyl) peroxide, t-butyl peroxyisobutyrate,
Examples include diisopropyl peroxydicarbonate and azobisbutyronitrile. Further, as the solvent,
For example, various chlorofluoroalkanes, various alcohols,
Various esters and the like can be used. Examples of the chlorofluoroalkane include trichlorofluoromethane, dichlorodifluoromethane, dichlorofluoromethane, chlorodifluoromethane, trifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, chloropentafluoroethane, difluoroethane and the like. Examples of alcohol include t-
Examples thereof include butanol and the like, and examples of the ester include methyl acetate, ethyl acetate and the like. In addition, a chain transfer agent can be added as necessary to control the molecular weight. Examples of the chain transfer agent include carbon tetrachloride, n-pentane, n-hexane, isopentane, trichlorofluoromethane, methanol and the like.

In the suspension polymerization, the ones listed in the above solution polymerization can be used as the radical initiator, the mixture of water and the chlorofluoroalkane mentioned in the above solution polymerization is used as the solvent, and the mixing ratio is water: chloro in a weight ratio. Fluoroalkane = 1:
It is 9 to 9: 1, preferably 1: 5 to 5: 1. Further, the chain transfer agent for the solution polymerization can be added if necessary. Further, it is desirable to add a fluorocarbon emulsifier such as C ₇ F ₁₅ COONH ₄ or C ₈ F ₁₇ COONH ₄ as a suspension stabilizer.

Radical polymerization initiators that can be used in emulsion polymerization are
A usual water-soluble radical polymerization initiator is used. For example, disuccinic acid peroxide, potassium persulfate, ammonium persulfate, t-butylperoxyisobutyrate, 2,2′-azobis-2-cyanopropane-4-sulfonic acid and the like. When a persulfate is used, it can be used as a so-called redox system by appropriately combining it with a reducing component. Examples of the reducing component include reducing agents such as sodium hydrogen sulfite, sodium thiosulfate and Rongalit. Furthermore, a small amount of iron, ferrous salt, or silver sulfate can be present alone or in combination with a stabilizer such as disodium ethylenediaminetetraacetate, particularly when Rongalit is used as a reducing component. Is desirable. It is also possible to use ionizing radiation as a radical polymerization initiation source.

In carrying out such emulsion polymerization, it is also preferable to use together an emulsion stabilizer, a pH buffer, a pH adjuster, a polymerization accelerator and other additives which are usually used. If necessary, a chain transfer agent for the solution polymerization can be added. Further, from the viewpoint of accelerating the polymerization or stabilizing the latex, it is preferable to use a mixed solution in which an organic solvent is added to water. As such an addition solvent, t-butanol, methyl acetate, trichlorotrifluoroethane and the like are suitable.
As the emulsifier, for example, a hydrocarbon-based surfactant such as sodium lauryl sulfate can be used, but a fluorocarbon emulsifier is preferable from the viewpoint of stabilizing the latex, for example, C ₇ F ₁₅ COONH ₄ , C ₈ F ₁₇ Use of COONH ₄ etc. is desirable.

The polymerization temperature may be appropriately selected depending on the initiator system used and is not particularly limited, but generally 0 to 10
A temperature of about 0 ° C is used. Further, the pressure is not particularly limited because it can be changed appropriately depending on the amount of the charged monomer and the temperature, but in general, about 0.1 to 100 atm is practical.

The present copolymer obtained by such a method is, for example, polyperfluoro (2-methylene-4-methyl-1,3-dioxolane) or tetrafluoroethylene / perfluoro (2-
Perfluoropolymers such as methylene-4-methyl-1,3-dioxolane) copolymers are provided with, for example, excellent gas permeation characteristics and high chemical stability, thermal stability, and other characteristics. It is soluble at room temperature in fluorine-based solvents such as trichlorotrifluoroethane and tetrachlorodifluoroethane.

Due to its physical property of being soluble in a solvent, this copolymer can be easily formed into a thin film of, for example, a few μ or less and coated on a substrate having a complicated shape with a thickness of several μ or less without defects such as pinholes. is there.

Specific application fields showing the usefulness of this copolymer include:
Examples thereof include coating materials, coating materials, insulating film materials, and separation membrane materials.

The composition and the like of the obtained copolymer can be recognized by means of elemental analysis, NMR and the like by a conventional method. The number average molecular weight was measured by gel permeation chromatography (GPC) after dissolving the copolymer in trichlorofluoroethane.

In the present invention, the gas permeability coefficient P was measured by using the low vacuum pressure method for each gas.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these examples.

Example 1 100 g of ion-exchanged water, 10 g of t-butanol, 1 g of ammonium perfluorononanoate (C ₈ F ₁₇ COONH ₄ ), 2 g of disodium phosphate (12 hydrate) were placed in a stainless steel autoclave with a stirrer having an internal volume of 260 cc. 0.22 g of caustic soda, 1 g of ammonium persulfate, 0.018 g of disodium ethylenediaminetetraacetate (dihydrate) and 0.015 g of ferrous sulfate (heptahydrate) were charged, and perfluoro (2-methylene-4-methyl-1,3-
After charging 30 g of dioxolane), the flange of the autoclave is closed. After freezing and degassing three times, add 19.1 g of chlorotrifluoroethylene to the degassed autoclave.
g charge. After stirring the autoclave and heating it to 25 ° C, Rongalit 0. dissolved in 2 g of degassed deionized water.
Press in 12g. The reaction temperature is kept at 25 ° C. After 12 hours, 0.06 g of Rongalit is further added in the same manner. After 17 hours from the initial addition of Rongalit, the unreacted chlorotrifluoroethylene was purged while cooling the autoclave, and then the produced copolymer was recovered by a usual method. 26.8 g of a resinous chlorotrifluoroethylene / perfluoro (2-methylene-4-methyl-1,3-dioxolane) copolymer was obtained. The number average molecular weight of the polymer determined by GPC was 60,000. The composition of the polymer determined by elemental analysis was chlorotrifluoroethylene / perfluoro (2-methylene-4-methyl-1,3-dioxolane) = 74/26 (molar ratio).

The polymer was pressed to obtain a 100 μm thick film. The permeation coefficient and permeation coefficient ratio of each gas in this membrane are shown in Tables 2 and 3.

The polymer was dissolved in trichlorotrifluoroethane at room temperature, cast using an applicator, and dried to obtain a self-supporting thin film having a thickness of 25 μm. The gas permeability coefficient of this thin film was substantially the same as that of the pressed membrane.

Table 1 shows the results of examining the chemical stability of the thin film by an acid and alkali immersion test.

From the above characteristics, it can be seen that the present copolymer is suitable as a material for a thin film and the like.

Further, the polymer was dissolved in trichlorotrifluoroethane, coated on an iron plate, and dried to a thickness of 3
A μ coating layer was obtained. No pinhole was detected when examined by a wet pinhole tester.

From the above characteristics, it is found that the present copolymer is not only suitable as a coating material, but also useful as a separation membrane material because a defect-free coating layer can be obtained.

Example 2 50 g of trichlorotrifluoroethane and 42 g of perfluoro (2-methylene-4-methyl-1,3-dioxolane) were charged into a stainless steel autoclave with an internal volume of 260 cc and equipped with a stirrer, and then the flange of the autoclave was closed. . After freeze-deaeration is repeated 3 times, 7.8 g of chlorotrifluoroethylene is charged into the deaerated autoclave. After stirring the autoclave and heating it to 40 ° C., 0.25 g of isopropyl peroxide dissolved in 2 g of degassed trichlorotrifluoroethane is injected under pressure. The reaction temperature is kept at 40 ° C. 16 hours after the addition of peroxide, unreacted chlorotrifluoroethylene was purged while cooling the autoclave, the flange was opened, and the polymer solution was recovered and reprecipitated in methanol. The reprecipitated polymer was thoroughly washed with methanol and ion-exchanged water, and then dried under reduced pressure at room temperature for 16 hours and then at 35 ° C. for 2 hours to obtain resinous chlorotrifluoroethylene / perfluoro (2-methylene-4-). 40 g of a methyl-1,3-dioxolane) copolymer was obtained. The number average molecular weight of the polymer was 30,000. The composition of the polymer obtained by elemental analysis is chlorotrifluoroethylene / perfluoro (2-
Methylene-4-methyl-1,3-dioxolane) = 33/67
(Molar ratio).

The polymer was dissolved in trichlorotrifluoroethane and a mixed solvent of trichlorotrifluoroethane / perfluoro (2-butyltetrahydrofuran) at room temperature.

The polymer was pressed to obtain a 100 μm thick film. The permeation coefficient and permeation coefficient ratio of each gas in this membrane are shown in Tables 2 and 3.

Reference Example 1 100 g of ion-exchanged water, 10 g of t-butanol, 1 g of ammonium perfluorononanoate (C ₈ F ₁₇ COONH ₄ ), 2 g of disodium phosphate (12 hydrate) were placed in a stainless steel autoclave equipped with a stirrer having an internal volume of 260 cc. Caustic soda 0.22g, ammonium persulfate 1g, ethylenediaminetetraacetic acid disodium (dihydrate) 0.018g, ferrous sulfate (heptahydrate) 0.0015g were charged, and perfluoro (2-methylene-4-methyl-1,3) was added.
After charging 19.6 g of (dioxolane) and 20 g of perfluoro (3,6-dioxa-5-methyl-nonene-1), the flange of the autoclave is closed. Freezing and degassing are repeated 3 times, and 12 g of chlorotrifluoroethylene is charged after degassing.
The reaction temperature is kept at 25 ° C, and 0.05 g of Rongalit is dissolved in water and injected. After 2 hours, the flange is opened and the latex is collected while cooling the autoclave. After thoroughly washing the polymer with methanol and ion-exchanged water, it was dried under reduced pressure at room temperature for 16 hours and then at 35 ° C. for 2 hours to give resinous chlorotrifluoroethylene / perfluoro (2-methylene-4-methyl-). 1,3-dioxolane) /
Perfluoro (3,6-dioxa-5-methyl-nonene-
1) 23.2 g of a copolymer was obtained. The number average molecular weight of the polymer was 50,000. The composition of the polymer obtained by elemental analysis is chlorotrifluoroethylene / perfluoro (2-
Methylene-4-methyl-1,3-dioxolane) / perfluoro (3,6-dioxa-5-methyl-nonene-1) = 6
It was 2/34/4 (molar ratio).

The polymer was dissolved in trichlorotrifluoroethane at room temperature.

The polymer was pressed to obtain a 100 μm thick film. The permeation coefficient and permeation coefficient ratio of each gas in this membrane are shown in Tables 2 and 3.

Comparative Example 1 50 g of trichlorotrifluoroethane, 50 g of perfluoro (2-methylene-4-methyl-1,3-dioxolane) and 0.12 g of isopropyl peroxide were charged into a glass flask equipped with a stirrer and having an internal volume of 100 cc. Freeze degassing 3
Repeat times. Polymerization is carried out at 42 ° C. After 4 hours, the polymer solution is collected and reprecipitated in methanol. The reprecipitated polymer was thoroughly washed with methanol and ion-exchanged water, and dried under reduced pressure at room temperature for 16 hours and then at 35 ° C for 2 hours to give a resinous perfluoro (2-methylene-4-methyl-).
20 g of 1,3-dioxolane) polymer was obtained.

The polymer was substantially insoluble in trichlorotrifluoroethane.

Furthermore, when the polymer was dissolved in perfluoro (2-butyltetrahydrofuran) at room temperature, it was partially insoluble.

Comparative Example 2 120 g of trichlorotrifluoroethane and 1% of perfluoro (2-methylene-4-methyl-1,3-dioxolane) were placed in a stainless steel autoclave equipped with a stirrer and having an internal volume of 260 cc.
After charging 7.5g and 0.12g of (C ₃ F ₇ COO) ₂ , close the flange of the autoclave. After freeze-deaeration was repeated 3 times, 27 g of tetrafluoroethylene was charged into the deaerated autoclave. The reaction temperature is kept at 35 ° C. 16 hours after the addition of peroxide, unreacted tetrafluoroethylene was purged while cooling the autoclave, then the flange was opened and the polymer solution was recovered and reprecipitated in methanol. The reprecipitated polymer was thoroughly washed with methanol and ion-exchanged water, then, under reduced pressure at room temperature for 16 hours, and at 35 ° C for 2
Resin-like tetrafluoroethylene / perfluoro (2-methylene-4-methyl-1,3-
31 g of a dioxolane) copolymer was obtained. The composition of the polymer determined by elemental analysis was tetrafluoroethylene / perfluoro (2-methylene-4-methyl-1,3-dioxolane) = 80/20 (molar ratio).

The polymer was substantially insoluble in trichlorotrifluoroethane and perfluoro (2-butyltetrahydrofuran).

[Effects of the Invention] The chlorotrifluoroethylene / perfluoro (2-methylene-4-methyl-1,3-dioxolane) copolymer of the present invention has an unprecedented copolymer weight in its chemical and physical properties. Although it is a coalesced product, it is a fluorine-based copolymer with particularly high chemical stability and thermal stability, but it has good processability due to its solvent solubility. It shows its usefulness. Specific application fields showing the usefulness of the present copolymer include, for example, coating materials, coating materials, insulating film materials, weather resistant film materials, and separation membrane materials.

Claims (2)

[Claims] 1. A number average molecular weight of 3,000 or more comprising a structural unit (A) polymerized with chlorotrifluoroethylene and a structural unit (B) polymerized with perfluoro (2-methylene-4-methyl-1,3-dioxolane). A chlorotrifluoroethylene-based copolymer, characterized in that the content of the structural unit (A) in the copolymer is 10 to 90 mol%. 2. The content of the structural unit (A) in the copolymer is 20.
The copolymer according to claim 1, which is -80 mol%.