CN101089024B - Fluorine-containing elastomer and its composition for vulcanization - Google Patents

Abstract

The present invention provides a fluoroelastomer and a curing composition thereof. The present invention provides a method for producing a fluoroelastomer with high productivity comparable to non-iodine transfer polymerization by performing iodine transfer polymerization under high pressure, and further provides an elastomer produced by this method with less branched chains and a high terminal iodine content A fluorine-containing elastomer, and a fluorine-containing molded article having an excellent balance of compression set and tensile elongation at break obtained by vulcanizing the elastomer.

Description

Fluorine-containing elastomer and its curing composition

This application is a divisional application, the international application number of the original application is PCT/JP2004/000519, the Chinese national application number is 200480002487.1, the application date is January 22, 2004, and the invention title is "Vulcanizable fluoroelastomer Manufacturing method".

technical field

The present invention relates to a process for the manufacture of fluoroelastomers by iodine transfer polymerization at high pressure. Furthermore, it relates to a fluorine-containing elastomer having few elastomer branches and a high terminal iodine content produced by the method, and a fluorine-containing elastomer having an excellent balance of compression set and tensile elongation at break obtained by vulcanizing the elastomer. moldings.

Background technique

Vinylidene fluoride-hexafluoropropylene (VdF-HFP) and tetrafluoroethylene (TFE)-perfluoroethylene ether fluoroelastomers exhibit excellent chemical resistance, solvent resistance, and heat resistance, so they are Made of O-rings, gaskets, hoses, rod seals, shaft seals, diaphragms, etc. used in harsh environments, widely used in the automotive industry, semiconductor industry, chemical industry and other fields.

As a fluoroelastomer used for these applications, there is an iodine-containing fluoroelastomer having a highly reactive iodine atom at a molecular terminal. The iodine-containing fluorine-containing elastomer can have good cross-linking efficiency through the iodine atom at the end of the molecule, and has excellent vulcanization properties. Also, it is widely used as a peroxide vulcanized molded product because it does not require the addition of chemical substances with metal components.

The peroxide vulcanization system (for example, refer to JP-A-53-125491 Bulletin) has superior chemical resistance and steam (hot water) resistance, but is not suitable for sealing due to its poor compression set resistance compared with polyol vulcanization systems. Material use. This problem has been solved by introducing vulcanization sites into the main chain of the elastomer (see, for example, JP-A-62-12734). However, tensile elongation at break is sacrificed in order to increase vulcanized density. Therefore, it is very difficult to achieve both compression set resistance and tensile elongation at break.

In addition, as a method of producing a fluoroelastomer by high-pressure polymerization, there are methods such as a polymerization method in which at least one monomer is in a supercritical state (for example, refer to International Publication No. 00/47641 pamphlet) and the method of fluorine-containing elastomer in polymer particles. Emulsion polymerization method in which the monomer concentration is higher than the reference value (for example, refer to International Publication No. 01/34666 pamphlet). Although there is a record in any reference document that the present invention can polymerize in the presence of R _f ¹ ·I _x , there is no specific example, and the effect disclosed in the present invention has not been achieved at all.

Fluorine-containing elastomers containing iodine are produced by emulsion polymerization methods such as the so-called iodine transfer polymerization method (for example, refer to Japanese Patent Publication No. 63-41928), but in order to achieve a high terminal iodination rate, it is necessary to control the amount of polymerization initiator used (For example, refer to Jianyuan Zhengxiang P19, 86/6 Microcosmic Symposium, Structural Rules of Polymers in Free Radical Polymerization, Polymer Society (1986)), and correspondingly, productivity cannot be improved. For the polymerization system where the amount of the polymerization initiator is not limited, the polymerization rate can be easily increased by increasing the amount of the initiator, but for the iodine transfer polymerization system, because the final concentration of the initiator will have a large impact on the physical properties of the final product, it is not desirable Increase the amount of initiator used.

Various proposals have been made to improve productivity. For example, a method of continuously carrying out emulsion polymerization to improve productivity has been proposed (for example, refer to JP-A-3-33108 and JP-A-3-221510), but good tensile strength and compression set cannot be obtained, and such Good properties are characteristic of iodine-containing fluoroelastomers.

In addition, a method of polymerizing at a high pressure of 1.7 MPa (gauge pressure, the same below) has been proposed (for example, refer to Japanese Patent Application Laid-Open No. 5-222130), but the pressure in the range of 2.6 MPa to 2.7 MPa is preferred. Examples are also limited to the disclosure within the scope. Furthermore, the polymerization time also exceeded 15 hours. Furthermore, a microemulsion polymerization method has been proposed (for example, refer to JP-A-63-8406), but it is necessary to use fluorine oil or the like in order to form a microemulsion in the initial stage, and since the fluorine oil or the like will remain in the product and become a source of contamination, washing is required. remove.

For the purpose of stabilizing the polymerization system or increasing the polymerization rate, the amount of emulsifier used can be increased, but since the emulsifier itself will cause vulcanization barriers, it needs to be removed by washing, and it is not ideal in terms of cost and environment.

In order to solve these problems, iodine transfer polymerization using a two-stage emulsion polymerization method has been proposed (see, for example, International Publication No. 00/01741 pamphlet). The so-called two-stage emulsion polymerization method is a method of synthesizing a large number of polymer particles using a relatively large amount of emulsifier in the first stage of polymerization, and then diluting the obtained emulsion to reduce the concentration of polymer particles and emulsifier. Dilute the emulsion for the second stage of polymerization. In this method, although it is not necessary to make major changes to the existing emulsion polymerization equipment, uniform particle size can be formed and its original characteristics can be maintained, and the polymerization rate can be shortened by more than 2 times. The productivity is still poor compared to the polymerization method. In addition, compared with the conventional iodine transfer polymerization method, the elastomer obtained by this polymerization method has no special improvement, and the above-mentioned problem of sealing performance remains.

There is no such production method of iodine-containing fluoroelastomers that balances productivity and maintenance of properties.

Contents of the invention

The present invention provides a method for producing a fluoroelastomer by performing iodine transfer polymerization under high pressure, which has a high productivity comparable to non-iodine transfer polymerization. Furthermore, there are provided fluoroelastomers with few polymer branches and high terminal iodine content produced by this method, and fluoroelastomers with excellent balance of compression set and tensile elongation at break obtained by vulcanizing the elastomer. Fluoroformed products.

That is, the present invention relates to a method for producing a fluorine-containing elastomer using a batch copolymerization method, which uses the Peng-Robinson equation to calculate critical The conversion temperature of the constant is 0.95 or more, and the conversion pressure is 0.80 or more, wherein the ethylenically unsaturated compound containing at least one fluoroolefin is copolymerized in the presence of the general formula R _f ¹ ·I _x , in the general formula, R _f ¹ is a saturated or unsaturated fluorocarbon group or chlorofluorocarbon group with 1-16 carbon atoms, and x is the bonding valence of R _f ¹ , which is an integer of 1-4.

The pressure during polymerization depends on the type and composition ratio of monomers to be copolymerized, and may be, for example, 4 MPa or more. The above pressure can be applied, for example, to the case where the fluoroelastomer to be obtained is a copolymer of vinylidene fluoride and hexafluoropropylene, and the molar ratio of vinylidene fluoride:hexafluoropropylene is 9:1 to 5:5. Also, the polymerization pressure may be, for example, 3 MPa or more. The above pressure can be applied, for example, to the case where the fluoroelastomer to be obtained is a copolymer formed of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, wherein vinylidene fluoride:hexafluoropropylene is in a molar ratio of 9:1 to 5 : 5 and tetrafluoroethylene is less than or equal to 40 mol% of the entire elastomer.

At the end of the polymerization, the number of fluoroelastomer particles per 1 g of water is preferably equal to or greater than 5×10 ¹³ .

Fluoroolefins are preferably CX ¹ X ² =CX ³ X ⁴ , wherein X ¹ to X ³ are hydrogen atoms or halogen atoms, and X ⁴ is hydrogen atoms, halogen atoms, carboxyl groups, 1 to 9 carbon atoms and some or all hydrogen An alkyl group containing or not containing ether-bonded oxygen atoms whose atoms are substituted by fluorine atoms, or an alkoxy group containing or not containing ether-bonding oxygen atoms with 1 to 9 carbon atoms and part or all of the hydrogen atoms replaced by fluorine atoms group, the olefin contains at least one fluorine atom.

The fluoroolefin is preferably selected from the group consisting of hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, pentafluoropropylene, fluoroethylene, hexafluoroisobutylene, perfluoro(alkyl vinyl ether), polyfluorodiene and the following formula Compounds in the group consisting of, wherein Y is -CH ₂ I, -OH, -COOH, -SO ₂ F, -SO ₃ M (M is NH ₄ or alkali metal), carboxylate, carboxylate, Epoxy group, nitrile group, iodine atom, X ⁵ and X ⁶ are the same or different, hydrogen atom or fluorine atom, R _f ² is a divalent fluorine-containing alkylene group with 0 to 40 carbon atoms, with or without Ether-bonded oxygen atom.

The Mooney viscosity of the fluoroelastomer at 100° C. is preferably 30 or more.

In addition, the present invention relates to a fluorine-containing elastomer containing 20 mol % to 90 mol % of repeating units of vinylidene fluoride and 10 mol % to 80 mol % of repeating units of hexafluoropropylene, wherein (a) The elastomer contains 0.01% to 10% by weight of iodine atoms, (b) the number average molecular weight of the polymer is 1,000 to 300,000, (c) an acetone solution with a polymer concentration of about 20% measured by high-resolution ¹⁹ F-NMR , through the following formula

If the obtained "VdF branching rate" is less than or equal to 200 ppm, the fluoroelastomer can be vulcanized by peroxide.

The vulcanized molded article preferably has a tensile elongation at break Eb of 200% to 550%, and a compression set CS at 200°C for 72 hours of 5% to 30%.

The present invention also relates to a composition for curing a fluoroelastomer comprising a fluoroelastomer and a vulcanizing agent.

Detailed ways

The manufacturing method of the fluoroelastomer of the present invention is the manufacturing method of the fluoroelastomer adopting the batch type copolymerization method, and it uses the Peng-Robinson equation to obtain the critical temperature and critical pressure of each monomer in the gas phase part in the reaction tank and the conversion temperature of the critical constants calculated from the respective composition ratios are greater than or equal to ^0.95 , _and the conversion pressure is greater than or equal to _0.80 . In the general formula, R _f ¹ is a saturated or unsaturated fluorocarbon group or chlorofluorocarbon group with 1 to 16 carbon atoms, x is the bonding valence of R _f , and It is an integer of 1 to 4.

The present invention provides a method for producing fluoroelastomers by performing iodine transfer polymerization at high pressure, in which the polymerization rate is greatly increased despite a small amount of polymerization initiator; high productivity. Furthermore, the elastomer produced by this method has few branched chains, high terminal iodine content, and can provide a superior fluorine-containing molded product having a small compression set and a good tensile elongation at break.

The production method of the present invention is characterized in that iodine transfer polymerization is carried out under high pressure. The iodine transfer polymerization method is not particularly limited, but it is preferable to increase the number of fluoropolymer particles at the end of polymerization in terms of productivity, and the seed polymerization method described in International Publication No. 00/01741 pamphlet is preferable as the method.

The reaction tank used in the present invention uses a pressure-resistant container because polymerization is performed under pressure. An aqueous medium (usually pure water) for emulsion polymerization containing polymer particles having the same composition as the target polymer is placed in the reaction tank to form a liquid phase.

The reaction tank is composed of the liquid phase part and the gas phase part, and the polymerizable monomer is introduced after replacing the gas phase part with nitrogen gas or the like. Next, the liquid phase part is particularly stirred in the reaction tank, and the polymerizable monomer is supplied from the gas phase part to the liquid phase part. The monomer supplied to the liquid phase penetrates into the polymer particles, and the concentration of the polymerizable monomer in the polymer particles increases. By continuously supplying the monomer to the gas phase, the monomer concentration in the polymer particles becomes saturated (it can also be said that the supply rate of the monomer to the liquid phase is in an equilibrium state), and a polymerization initiator and iodide are injected to start polymerization.

As the polymerization proceeds, the monomer is consumed, and the concentration of the monomer in the produced polymer particles gradually decreases. Therefore, it is often necessary to continuously supply the monomer to the polymer particle (additional monomer).

The ratio of the added monomer depends on the composition of the monomer to be added and the target polymer, and it is preferable to keep the ratio of the monomer composition in the reaction tank at the initial stage of polymerization constant.

In addition, at the end of the polymerization, the number of fluoroelastomer particles per 1 g of water is preferably 5×10 ¹³ or more, more preferably 1.0×10 ¹⁴ or more particles per 1 g of water. When the number of particles is less than 5×10 ¹³ , not only the reaction rate decreases, but also the particle size becomes extremely unstable, and the adhesion of the polymer to the polymerization tank tends to increase.

As a polymerization method for increasing the number of particles at the end of polymerization, in addition to the seed polymerization method, the microemulsion method described in Japanese Patent Publication No. 63-8406 and Japanese Patent Publication No. 62-288609, and increasing the amount of emulsifier as a general method wait. Among them, in the microemulsion method, it is necessary to use fluorine oil or the like in order to form a microemulsion in the initial stage, so the oil remains in the product, which becomes a source of contamination and needs to be removed by washing. In addition, to increase the amount of emulsifier, only stabilizing the polymerization system or increasing the polymerization rate is effective, but foaming tends to occur before and after polymerization, and the emulsifier remaining in the obtained elastomer tends to cause vulcanization barriers. Also, it is not an ideal method in terms of cost and environment. On the other hand, the seed polymerization method does not have the above-mentioned problems and shows excellent effects in the iodine transfer system.

In the production method of the present invention, in order to correct some errors in the critical temperature and critical pressure of the gas phase monomer mixture, the converted temperature is greater than or equal to 0.95, preferably greater than or equal to 0.97, and the converted pressure is greater than or equal to 0.80, preferably greater than or equal to 0.85 Batch polymerization is carried out under certain conditions, and the critical temperature and critical pressure of the gas-phase monomer mixture are derived from the independent critical temperature, critical pressure and initial monomer composition ratio of each monomer through the Peng-Robinson equation. By making the conversion temperature and conversion pressure of the mixed monomers in the gas phase part exceed the above values, it is possible to carry out polymerization with a high monomer density, and in addition to increasing the polymerization speed, it is also possible to obtain a polymer with fewer branched chains and ionic terminals in the main chain. , thus the compression set is greatly improved. Here, the so-called converted temperature is a value determined by the converted temperature T _R =T/T _c (where T is the actual temperature during polymerization, and T _c is the critical temperature calculated using the Peng-Robinson equation), and the so-called converted pressure It is a numerical value determined by P _R =P/P _c (where P is the actual pressure during polymerization, and P _c is the critical pressure calculated using the Peng-Robinson equation).

Here, the Peng-Robinson equation that determines the critical temperature and critical pressure will be described. In general, it is known that the higher the initial monomer density in the polymerization tank, the easier the composition distribution occurs in the obtained polymer, and the initial monomer density rises particularly sharply from the vicinity of the critical point. However, when monomers of two or more components are copolymerized, the critical point of the gas-phase monomer mixture varies depending on the type and composition ratio of the monomers. The Peng-Robinson equation is used as a method for calculating the critical point of the mixed monomers from the critical temperature, critical pressure, and initial monomer composition ratio of each individual monomer. The principle of this equation is described in D.Y.Peng and D.B.Robinson, "A New Two-Constant Equation of state", Ind.Eng.Chem.Fund., Vol.15, (1976), p.59-64. The outline is based on the following formula as a principle, and a program simulator such as Aspen Plus (manufactured by Aspen Technology Co., Ltd.) can be used for actual calculation.

The outline of the Peng-Robinson equation is as follows.

P＝RT/(V _m -b)-a/[V _m (V _m +b)+b(V _m -b)]

$\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 0.5</span>}}$

$\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; xb</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}$

Here, a _i and b _i in the above formulas are respectively defined as follows.

a _i =α _i 0.45724R ² T _ci ² /P _ci

α _i (T)=[1+m _i (1-T _ci ^0.5 )] ²

m _i =0.37464+1.54226ω _i -0.26992ω _i ²

b _i =0.0778RT _ci /P _ci

In addition, the meaning of each parameter is as follows.

P: pressure

T: temperature

V _m : Volume

R: gas constant

Xi: Composition ratio of monomer component i

T _ci : critical temperature of monomer component i

P _ci : critical pressure of monomer component i

ω _i : eccentricity factor of monomer component i

As a specific calculation example, when the composition in the polymerization tank is VdF/HFP=36/64 (mol%), Aspen Plus Ver.11.1 (manufactured by Aspen Technology Co., Ltd.) is used to calculate the critical temperature and critical pressure using the Peng-Robinson equation. The result is T _c =87.7°C, P _c =3.05 MPa. If conversion is carried out using the conversion temperature of 0.95 and the conversion pressure of 0.80, the polymerization conditions at this time are T 69.7° C. or higher and P 2.44 MPa or higher.

If the converted temperature is less than 0.95 or the converted pressure is less than 0.80, the monomer concentration in the polymer particles will not be saturated, and not only the polymerization rate will be reduced, but it will often be difficult to obtain the target polymer. Among the temperature and pressure that satisfy the conditional formula calculated from the above formula, the more preferred polymerization temperature is 10°C to 120°C, particularly preferably 30°C to 100°C; the preferred polymerization pressure is 3 MPa or more, more preferably 3.5 MPa, and even more preferably It is greater than or equal to 4MPa. In addition, the upper limit of the pressure is not particularly limited, but it is preferably equal to or less than 15 MPa, more preferably equal to or less than 12 MPa, considering the operability of monomers and the cost of reaction equipment.

Furthermore, stirring is preferably performed. This is due to the fact that a high monomer concentration in the polymer particles can be maintained through the polymerization by stirring.

As the stirring means, for example, anchor blades, turbine blades, inclined blades, etc. can be used, but from the viewpoint of good dispersion stability of monomers and polymers, it is preferable to use large blades called fulzoan and masquesbrend. Stir.

As the stirring device, a horizontal stirring device or a vertical stirring device may be used.

The reaction system essentially has a monomer phase portion. Here, substantially having a monomer phase means that the polymerization is carried out in a state where the volume occupied by a medium such as water is equal to or less than 90%, preferably equal to or less than 80%, of the volume of the polymerization vessel. When the volume exceeds 90%, it becomes difficult to supply the monomer to the medium, the polymerization rate tends to decrease, or the physical properties of the polymer tend to deteriorate.

In the iodides represented by the general formula: R _f ¹ ·I _x used in the present invention, R _f ¹ is a saturated or unsaturated fluorocarbon group or chlorofluorocarbon group with 1 to 16 carbon atoms, preferably 4 carbon atoms ~8 perfluoroalkyl groups. When the number of carbon atoms exceeds 16, the reactivity tends to decrease.

In the iodide represented by the general formula: R _f ¹ ·I _x , x is the bonding valence of R _f ¹ and is an integer of 1-4, preferably 2-3. Even if x exceeds 4, it can be used, but it is not preferable in terms of synthesis cost. x is most preferably 2 from the viewpoint that the polymer has few branches.

The carbon-iodine bond of this iodide is a relatively weak bond, and it cleaves into a radical in the presence of a radical generating source. Due to the high reactivity of the generated radicals, the addition reaction of the monomer occurs, and then the reaction is stopped by attracting iodine from the iodide. The thus obtained fluoroelastomer in which iodine is bonded to the carbon at the terminal of the molecule can effectively vulcanize because the terminal iodine becomes an effective vulcanization site.

As the iodide represented by the general formula: R _f ¹ ·I _x , monoiodoperfluoromethane, monoiodoperfluoroethane, monoiodoperfluoropropane, monoiodoperfluorobutane (for example, 2-iodoperfluorobutane, etc.) Fluorobutane, 1-iodoperfluoro(1,1-dimethylethane)), monoiodoperfluoropentane (e.g. 1-iodoperfluoro(4-methylbutane)), 1-iodoperfluoro n-octane, monoiodoperfluorocyclobutane, 2-iodoperfluoro(1-cyclobutylethane)cyclohexane, monoiodoperfluorocyclohexane, monoiodotrifluorocyclobutane, monoiododifluoro Methane, monoiodomonofluoromethane, 2-iodo-1-hydroperfluoroethane, 3-iodo-1-hydroperfluoropropane, monoiodomonochlorodifluoromethane, monoiododichloromonofluoromethane, 2-iodo -1,2-dichloro-1,1,2-trifluoroethane, 4-iodo-1,2-dichloroperfluorobutane, 6-iodo-1,2-dichloroperfluorohexane, 4 -Iodo-1,2,4-trichloroperfluorobutane, 1-iodo-2,2-dihydroperfluoropropane, 1-iodo-2-hydroperfluoropropane, monoiodotrifluoroethylene, 3-iodo Perfluoropropene-1,4-iodoperfluoropentene-1, 4-iodo-5-chloroperfluoropentene-1,2-iodoperfluoro(1-cyclobutenylethane), 1,3- Diiodoperfluoropropane, 1,4-diiodoperfluoro-n-butane, 1,3-diiodo-2-chloroperfluoropropane, 1,5-diiodo-2,4-dichloroperfluoro-n-pentane , 1,7-diiodoperfluorooctane, 1,2-bis(iododifluoromethyl)perfluorocyclobutane, 2-iodo-1,1,1-trifluoroethane, 1-iodo- 1-hydroperfluoro(2-methylethane), 2-iodo-2,2-dichloro-1,1,1-trifluoroethane, 2-iodo-2-chloro-1,1,1- Trifluoroethane, etc. Furthermore, the hydrocarbon group of R _f ¹ may contain functional groups such as an ether-bonding oxygen atom, a thioether-bonding sulfur atom, and a carboxyl group, examples of which include 2-iodoperfluoroethyl perfluorovinyl ether, 2-iodoperfluoroethyl Perfluoroisopropyl ether, 3-iodo-2-chloroperfluorobutyl perfluoromethyl sulfide, 3-iodo-4-chloroperfluorobutyric acid, etc.

Among them, 1,4-diiodoperfluoro-n-butane is preferable from the viewpoints of ease of synthesis, reactivity, economy, and stability.

These iodine compounds can be produced by an appropriate known method. For example, 2-iodoperfluoropropane can be produced by reacting hexafluoropropane and iodine in the presence of potassium fluoride, and 1,5-diiodo-2,4-dichloroperfluoro-n-pentane can be produced by making 3,5 - The silver salt of dichloroperfluoro-1,7-pimelic acid reacts with iodine, and 4-iodo-5-chloroperfluoro-1-pentene can be produced by making iodine chloride and perfluoro-1, 4-pentadiene reaction and production.

The amount of the iodine compound added is preferably 0.05% by weight to 2.0% by weight relative to the fluoroelastomer. When the added amount is less than 0.05% by weight, the vulcanization tends to be insufficient and the compression set (CS) deteriorates; when it exceeds 2.0% by weight, the crosslinking density becomes too high, and properties such as elongation of the rubber tend to be impaired.

At least one or more than one fluoroolefin is contained as a monomer forming the fluoroelastomer with the above-mentioned iodine compound, and an ethylenically unsaturated compound other than fluoroolefin may be contained as a comonomer thereof.

This composition is preferred for forming fluoroelastomers.

The fluoroolefin used in the present invention is preferably an olefin represented by CX ¹ X ² =CX ³ X ⁴ . In the formula, X ¹ to X ³ are hydrogen atoms or halogen atoms, and X ⁴ is hydrogen atoms, halogen atoms, carboxyl groups, carbon atoms of 1 to 9 and some or all of the hydrogen atoms are substituted by fluorine atoms, containing or not containing ether bonds An alkyl group having 1 to 9 carbon atoms and a part or all of the hydrogen atoms being substituted by fluorine atoms, which may or may not contain an ether-bonding oxygen atom, and the alkene contains at least one fluorine atom.

Examples of the fluoroolefin represented by CX ¹ X ² =CX ³ X ⁴ include hexafluoropropylene (HFP), vinylidene fluoride (VdF), tetrafluoroethylene (TFE), trifluoroethylene, pentafluoropropylene, vinyl fluoride , hexafluoroisobutylene, chlorotrifluoroethylene (CTFE), trifluoropropylene, pentafluoropropylene, tetrafluoropropylene, hexafluoroisobutylene, perfluoro(alkyl vinyl ether) (PAVE), etc., which are easily obtained from elastomers From a viewpoint, vinylidene fluoride (VdF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and perfluoro(alkyl vinyl ether) (PAVE) are preferred.

In addition, perfluoro(alkyl vinyl ether)s are also preferable in terms of cold resistance and chemical resistance.

Examples of perfluoro(alkyl vinyl ether) include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), perfluoro(propyl vinyl ether) ( PPVE) etc.

CF₂＝CFOCF₂CF＝CF₂表示的氟烯烃、用

表示的含有官能团的氟烯烃和聚氟二烯类等(式中Y为-CH₂I、-OH、-COOH、-SO₂F、SO₃M(M为氢、NH₄基或者碱金属)、羧酸盐、羧酯基、环氧基、腈基、碘原子；X⁵和X⁶相同或者不同，均为氢原子或者氟原子；R_f ²是碳原子数为0～40的2价的含氟亚烷基，可以含有醚键性氧原子)。In addition, examples of fluoroolefins other than CX ¹ X ² =CX ³ X ⁴ include

CF ₂ ＝CFOCF ₂ The fluoroolefin represented by CF ＝ CF ₂ is represented by

Fluoroolefins and polyfluorodienes containing functional groups, etc. (where Y is -CH ₂ I, -OH, -COOH, -SO ₂ F, SO ₃ M (M is hydrogen, NH ₄ or alkali metal) , carboxylate, carboxyl ester group, epoxy group, nitrile group, iodine atom; X ⁵ and X ⁶ are the same or different, both are hydrogen atom or fluorine atom; R _f ² is divalent with 0-40 carbon atoms The fluorine-containing alkylene group may contain an ether-bonding oxygen atom).

Fluoroolefins containing functional groups are preferred as functional monomers such as surface modification and crosslinking density improvement, while polyfluorodienes are preferred in terms of crosslinking efficiency.

Examples of fluoroolefins containing functional groups include:

CF ₂ =CFOCF ₂ CF ₂ CH ₂ OH,

CF ₂ =CFOCF ₂ CF ₂ COOCH ₃ ,

CF₂＝CFCF₂COOH、

CF ₂ =CFCF ₂ COOH,

_CF2 = _{CFCF2CH2OH ,}

CF ₂ = CFCF ₂ OCF ₂ CF ₂ CF ₂ COOH,

CF₂＝CFOCF₂CF₂SO₂F、

CF ₂ =CFOCF ₂ CF ₂ SO ₂ F,

CF ₂ = CFCF ₂ CF ₂ COOH, CF ₂ = CFCF ₂ COOH,

_{CH2 = CFCF2CF2CH2CH2OH , CH2 = CFCF2CF2COOH ,}

_{CH2 = CHCF2CF2CH2CH2COOH , _}

等。

wait.

As the functional group-containing fluoroolefin, the monomer CF ₂ =CFOCF ₂ CF ₂ CH ₂ I disclosed in Patent Document 2 is preferable in order to increase the crosslink density.

Examples of the polyfluorodienes include CF ₂ =CFCF=CF ₂ , CF ₂ =CFCF ₂ OCF=CF ₂ and the like.

The ethylenically unsaturated compounds other than fluoroolefins are not particularly limited, and include α-olefin monomers having 2 to 10 carbon atoms such as ethylene (ET), propylene, butene, and pentene; methyl vinyl ether , ethyl vinyl ether, propyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, butyl vinyl ether and other alkyl vinyl ethers having an alkyl group with 1 to 20 carbon atoms, etc. .

These compounds are preferable in terms of low cost and amine resistance.

As a combination of monomers forming the fluoroelastomer of the present invention, there are one or more fluoroolefins represented by the above CX ¹ X ² =CX ³ X ⁴ and one or more CX ¹ X ² = Fluoroolefins other than CX ³ X ⁴ , and one or more types of fluoroolefins represented by the above CX ¹ X ² =CX ³ X ⁴ and one or more types of CX ¹ X ² =CX ³ X Combinations of fluoroolefins other than ⁴ , and comonomers of each combination may contain ethylenically unsaturated compounds other than fluoroolefins.

Among the above-mentioned fluoroolefins and ethylenically unsaturated compounds other than fluoroolefins, in order to form a fluorine-containing elastomer having good vulcanization at low cost, it is preferable to form an ethylenically unsaturated compound copolymerizable with vinylidene fluoride (VdF).

The Mooney viscosity at 100°C of the fluoroelastomer produced by the production method of the present invention is preferably 30 or more, more preferably 35 or more, and the elongation rate is higher than that of conventional products of the same viscosity by peroxide vulcanization. Large, compression set (CS) and excellent roll processability. The higher the viscosity range, the greater the difference in compression set (CS) from conventional products.

If the Mooney viscosity is less than 30, the cross-linking efficiency of the conventional product of the same viscosity is improved, and the difference from the conventional product tends to be small, but it does not deteriorate compared to the conventional product.

Next, the new fluoroelastomer of the present invention contains 20 mol% to 90 mol% of vinylidene fluoride repeating units and 10 mol% to 80 mol% of hexafluoropropylene repeating units, wherein (a) in the elastomer Containing 0.01% by weight to 10% by weight of iodine atoms, (b) the number average molecular weight of the polymer is 1,000 to 300,000, (c) an acetone solution with a polymer concentration of about 20% measured by high-resolution ¹⁹ F-NMR, obtained by the following Mode

If the obtained "VdF branching rate" is less than or equal to 200 ppm, the fluoroelastomer can be vulcanized by peroxide.

The fluoroelastomer of the present invention can be produced by the above-mentioned method.

The fluoroelastomer of the present invention preferably contains 20 mol% to 90 mol% of vinylidene fluoride (VdF) repeating units, more preferably 40 mol% to 85 mol%; preferably contains 10 mol% to 80 mol% of vinylidene fluoride (VdF) and hexafluoropropylene (HFP) repeating units are more preferably 15 mol% to 60 mol%.

The fluorine-containing elastomer formed of a binary copolymer of VdF and HFP preferably has a VdF branching ratio defined below equal to or less than 200 ppm, more preferably equal to or less than 150 ppm. When the VdF branching rate exceeds 200 ppm, especially in peroxide-cured elastomers containing iodine, the vulcanization efficiency decreases due to the reduction of iodine terminals, and various physical properties such as compression set (CS) tend to deteriorate.

The VdF/HFP fluoroelastomer having a VdF branching rate of 200 ppm or less can be copolymerized with other monomers within a range that does not impair its properties. As other copolymers, for example, tetrafluoroethylene can be exemplified. Examples of the copolymer composition include 30 mol% to 89 mol% of vinylidene fluoride (VdF) repeating units, 10 mol% to 50 mol% of hexafluoropropylene (HFP) repeating units, 0.1 mol% to 40 mol% of Tetrafluoroethylene (TFE) repeat unit.

The acetone solution (concentration: about 20%) of the polymer was measured by high-resolution ¹⁹ F-NMR, and the "VdF branching ratio" was obtained by the following calculation formula.

The branching specified above mainly refers to the

The area of the CF ₂ group adjacent to the branched CH group in such a structural unit appears between δF -96.5 to -99.5 ppm. The ratio of the area of this peak to the total area of all CF ₂ groups appearing at δF -88.0 to -124.0 ppm is the branching ratio. However, since there are 3 branched adjacent _CF2 groups relative to one _CF2 chain, the branching ratio corresponding to the unit VdF was calculated to be 1/3 of this measured value.

Here, the term "high resolution" refers to measurement with a spectrometer of 500 MHz or higher.

In addition, the fluorine-containing elastomer preferably contains 0.01% by weight to 10% by weight of iodine atoms in the elastomer, more preferably 0.05% by weight to 2.0% by weight. If the iodine atom content is less than 0.05% by weight, the vulcanization is insufficient and the compression set tends to deteriorate; when it exceeds 2.0% by weight, the crosslinking density is too high, the elongation is too small, etc., and the performance of the rubber tends to deteriorate.

Furthermore, it is preferable that the number average molecular weight of an elastomer is 1,000-300,000. When the molecular weight is less than 1,000, the viscosity tends to be too low and handleability tends to deteriorate; when it exceeds 300,000, the viscosity tends to be too high and handleability also tends to deteriorate.

The molecular weight distribution (weight average molecular weight Mw/number average molecular weight Mn) is preferably equal to or greater than 1.5, more preferably equal to or greater than 1.8. When the molecular weight distribution is less than 1.5, there is no problem in terms of physical properties, but roll workability tends to deteriorate.

In addition, a segmented elastomer obtained by further gradually polymerizing a crystalline segment on the obtained fluoroelastomer can be suitably used as a thermoplastic or the like.

The crystalline segment is not particularly limited, and examples thereof include tetrafluoroethylene, perfluoro(propyl)vinyl ether, hexafluoropropylene, ethylene (ET), propylene, and butene.

In the production method of the present invention, an oil-soluble radical polymerization initiator or a water-soluble radical initiator can be used as a polymerization initiator.

As the oil-soluble radical polymerization initiator used in the present invention, commonly known oil-soluble peroxides can be used, and typical examples include diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, and di-sec-butyl peroxydicarbonate. Dialkyl peroxycarbonates such as carbonates; Peroxyesters such as tert-butyl peroxyisobutyrate and tert-butyl peroxytrimethyl acetate; Di-tert-butyl peroxide and other dioxane peroxides Base class; also di(ω-hydrogen-dodecafluoroheptanoyl), di(ω-hydrogen-tetrafluoroheptanoyl) peroxide, bis(ω-hydrogen-hexadecafluorononanoyl) peroxide, Di(perfluorobutyryl), di(perfluorovaleryl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide , di(perfluorooctanoyl) peroxide, di(perfluorononanoyl) peroxide, di(ω-chloro-hexafluorobutyryl) peroxide, di(ω-chloro-decafluorohexanoyl) peroxide, peroxide Di(ω-chloro-tetrafluorooctanoyl) oxide, ω-hydrogen-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-peroxide Decafluorohexanoyl peroxide, ω-hydrogen dodecafluoroheptanoyl-perfluorobutyryl peroxide, bis(dichloropentafluorobutyryl) peroxide, bis(trichlorooctafluorohexanoyl) peroxide, bis(tetrafluorohexanoyl peroxide) Chloroundecafluorooctanoyl), bis(pentachlorotetrafluorodecanoyl), bis(undecachlorodocofluorobehenyl) peroxide, etc. Acyl] class, etc.

However, peroxycarbonates such as diisopropyl peroxycarbonate (IPP) and di-n-propyl peroxycarbonate (NPP), which are typical oil-soluble initiators, have a problem in that they have the risk of explosion , is expensive, and the scale generated during the polymerization reaction is easy to adhere to the wall surface of the polymerization tank, etc., so it is preferable to use a water-soluble radical polymerization initiator.

As the water-soluble radical polymerization initiator, generally known water-soluble peroxides are used, for example, ammonium salts, potassium salts, sodium salts, peroxygen persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, percarbonic acid, etc. tert-butyl maleate, tert-butyl hydroperoxide, etc.

The amount of the water-soluble radical initiator added is not particularly limited, and it can be added at the initial stage of polymerization at one time, in batches, or continuously in an amount that does not significantly reduce the polymerization rate (for example, several ppm for water concentration). The upper limit is the range in which the polymerization reaction heat can be dissipated from the surface of the device.

In the production method of the present invention, an emulsifier, a molecular weight regulator, a pH regulator, and the like may also be added. The molecular weight modifier may be added at one time initially, or may be added continuously or batchwise.

As the emulsifier, nonionic surfactants, anionic surfactants, and cationic surfactants can be used, and fluorine-based anionic surfactants such as ammonium perfluorooctanoate are particularly preferable. The added amount is preferably 50 ppm to 5000 ppm.

As the molecular weight regulator, for example, esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, dimethyl succinate; and isopentane, Isopropanol, acetone, various mercaptans, carbon tetrachloride, cyclohexane, monoiodomethane, 1-iodomethane, 1-iodo-n-propane, isopropane iodide, diiodomethane, 1,2-diiodo Methane, 1,3-diiodo-n-propane, etc.

In addition to this, a buffer or the like may be appropriately added, but the amount used should be within a range that does not impair the effects of the present invention.

The fluorine-containing elastomer composition of the present invention includes the above-mentioned fluorine-containing elastomer and a vulcanization agent, and may also contain a vulcanization assistant.

The vulcanizing agent that can be used in the present invention can be appropriately selected according to the vulcanization system used. Any of polyamine vulcanization system, polyol vulcanization system, and peroxide vulcanization system can be used as the vulcanization system, and the effect of the present invention can be exhibited particularly when vulcanization is performed with a peroxide vulcanization system.

As the vulcanizing agent, the polyol vulcanization system includes polyhydroxy compounds such as bisphenol AF, hydroquinone, bisphenol A, diaminobisphenol AF; the peroxide vulcanization system includes, for example, α, α'-bisphenol (tert-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide and other organic peroxides; polyamines Examples of the vulcanization system include polyamine compounds such as hexamethylenediamine carbamate and N,N'-dicinnamylidene-1,6-hexamethylenediamine. But it is not limited to these.

Among them, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane is preferable from the viewpoint of vulcanization and handleability.

The compounding quantity of a vulcanizing agent is 0.01-10 weight part with respect to 100 mass parts of elastomers, Preferably it is 0.1-5 weight part. When the vulcanizing agent is less than 0.01 parts by weight, the degree of vulcanization is insufficient, so the performance of fluorine-containing molded products tends to be impaired; Not preferred.

As vulcanization aids for polyol vulcanization systems, organic bases generally used for vulcanization of elastomers, such as various quaternary ammonium salts, quaternary phosphonium salts, cyclic amines, and monofunctional amine compounds, can be used. Specific examples include tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltributylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium hydrogensulfate, tetrabutylammonium hydroxide Ammonium and other quaternary ammonium salts; benzyltriphenylphosphine chloride, tributylallylphosphine chloride, tributyl-2-methoxypropylphosphine chloride, benzylphenyl (dimethyl Amino) phosphine and other quaternary phosphine salts; benzylmethylamine, benzyl ethanolamine and other monofunctional amines; 1,8-diazabicyclo[5.4.0]-undec-7-ene and other cyclic amines, etc.

Examples of vulcanization aids for peroxide vulcanization systems include triallyl cyanurate, triallyl isocyanurate (TAIC), tris(diallylamine-s-triazine), Triallyl phosphite, N,N-diallyl acrylamide, hexaallyl phosphoramide, N,N,N',N'-tetraallyl tetraphthalamide, N,N,N' , N'-tetraallyl malonamide, trivinyl isocyanurate, 2,4,6-trivinylmethyltrisiloxane, tris(5-norbornene-2-methylene ) cyanurate, etc. Among them, triallyl isocyanurate (TAIC) is preferable in view of vulcanization properties and physical properties of sulfides.

The compounding quantity of a vulcanization aid is 0.01-10 weight part with respect to 100 weight part of elastomers, Preferably it is 0.1-5.0 weight part. When the vulcanization aid is less than 0.01 parts by weight, the vulcanization time tends to be long, so that it is not practical; when it exceeds 10 parts by weight, the compression set of the molded product tends to decrease in addition to the fast vulcanization time.

Furthermore, as long as the purpose of the present invention is not impaired, fillers, processing aids, carbon black, inorganic fillers, metal oxides such as magnesium oxide, metal hydroxides such as calcium hydroxide, etc. .

The preparation and vulcanization methods of the composition of the present invention are not particularly limited, and conventionally known methods such as compression molding, extrusion molding, transfer molding, and injection molding can be used.

The tensile elongation at break (Eb) of the molded article vulcanized with the fluoroelastomer using a vulcanizing agent is preferably 200% to 550%. When the tensile elongation at break is less than 200%, the so-called "rubber elasticity" will disappear, and it is often not suitable as a sealing material; when it exceeds 550%, the crosslinking density is too low, and the compression set (CS) tends to deteriorate.

In addition, the compression set (CS) of the molded article at 200° C. for 72 hours is preferably 5% to 30%, more preferably 7% to 25%. When the compression set is less than 5%, the sealing performance is good, but generally the elongation is often too small; if it exceeds 30%, the performance of the sealing material tends to deteriorate.

Here, the vulcanization in the present invention means that vulcanization is carried out under standard vulcanization conditions according to the standard formulation shown below.

(standard fit)

Fluorine-containing elastomer 100 parts by weight

Triallyl isocyanurate (TAIC) 4 parts by weight

パ一ヘキサ25B (PERHEXA 25B) 1.5 parts by weight

Carbon black MT-C 20 parts by weight

(Standard Vulcanization Conditions)

Mixing method: roller mixing

Press vulcanization: 10 minutes at 160°C

Baking vulcanization: 4 hours at 180°C

Compared with the conventional iodine transfer polymerization reaction under low pressure, the production method of the present invention greatly shortens the polymerization time, and furthermore, the roll processability of the obtained fluoroelastomer is improved. Thereby, when comparing the fluorine-containing elastomer obtained by low-pressure iodine transfer polymerization and the product of the present invention with the same Mooney viscosity, the low-pressure product precipitates vulcanizing agent (TAIC) during mixing, and the rubber tends to break easily; while the product of the present invention Products did not find such a phenomenon.

Compositions containing the fluoroelastomer obtained by the present invention and a vulcanizing agent can be suitably used as coating agents, substrate-integrated gaskets and seals formed by dispersion molding on substrates containing inorganic materials such as metals and ceramics Multilayer products formed by coating on substrates containing inorganic materials such as metals and ceramics, gaskets for magnetic recording devices, sealing materials for fuel cells, and sealing materials for purification equipment.

Evaluation method

<Weight average molecular weight (Mw) and number average molecular weight (Mn)>

Device: HLC-8000 (manufactured by Tosoh Corporation)

Showa Pillar: GPC KF-806M 2 pieces

GPC KF-801 1 piece

GPC KF-801 2 pieces

Detector: Differential refractometer

Developing solvent: tetrahydrofuran

Temperature: 35°C

Sample concentration: 0.1% by weight

Standard samples: various monodisperse polystyrene ((Mw/Mn) = 1.14 (Max)), TSK standard polystyrene (manufactured by Tosoh Corporation)

<Mooney viscosity>

Measured according to ASTM-D1646 and JIS K6300 standards.

Measuring instrument: Model MV2000E manufactured by ALPHA Science and Technology Co., Ltd.

Rotor speed: 2rpm

Measuring temperature: 100°C

<Compression Set (CS)>

Under the following standard vulcanization conditions, the following standard compounds were subjected to one press vulcanization and two bake vulcanizations to produce O-rings (P-24), and the compression set after one press vulcanization was measured according to JIS-K6301 and the compression set (CS) after the second bake vulcanization (the sample was measured after being kept at 200° C. for 72 hours under 25% pressurized compression and left in a constant temperature room at 25° C. for 30 minutes).

(standard fit)

Fluorine-containing elastomer 100 parts by weight

Triallyl isocyanurate (TAIC) 4 parts by weight

パ一ヘキサ25B (PERHEXA 25B) 1.5 parts by weight

Carbon black MT-C 20 parts by weight

(Standard Vulcanization Conditions)

Mixing method: roller mixing

Press vulcanization: 10 minutes at 160°C

Baking vulcanization: 4 hours at 180°C

<100% tensile stress (modulus) (M100)>

Under the standard vulcanization conditions, the standard compound is subjected to press vulcanization once and bake vulcanization twice to form a thin sheet with a thickness of 2mm, which is measured according to the JIS-K6251 standard.

<Tensile strength at break (Tb) and tensile elongation at break (Eb)>

Under the standard vulcanization conditions, the standard compound is subjected to press vulcanization once and bake vulcanization twice to form a thin sheet with a thickness of 2mm, which is measured according to the JIS-K6251 standard.

<Hardness (Hs)>

Under the standard vulcanization conditions, the standard compound is subjected to press vulcanization once and bake vulcanization twice to form a thin sheet with a thickness of 2mm, which is measured according to the JIS-K6253 standard.

<Vulcanization characteristics>

During the primary press vulcanization, use the JIR type vulcanization meter (Kyulastmeter) type II and type V to obtain the vulcanization curve at 170°C, and obtain the minimum viscosity (ML), degree of vulcanization (MH), induction time (T ₁₀ ) and optimal curing time (T ₉₀ ).

<Measurement of Average Particle Size of Polymer>

The particle size was measured with a microtracer 9340UPA (manufactured by Honeywell).

<Particle number calculation>

The number of particles was calculated from the following formula using the measurement results of the average particle diameter of the above-mentioned polymer.

<VdF Branching Ratio Measurement>

The measurement sample was dissolved in acetone so that the concentration was about 20%. It was measured by ¹⁹ F-NMR (AMX500 type manufactured by Bruker Co., Ltd.), and MestRe-C2.3a (manufactured by MestRe-C Science and Technology Co., Ltd.) was used as the processing software to calculate the branched peak area and the total CF ₂ peak area. Find the branching ratio of the result.

<Composition Analysis>

Measurement was performed using ¹⁹ F-NMR (AMX500, manufactured by Bruker). However, the TFE-containing polymer was measured using ¹⁹ F-NMR (model FX100 manufactured by JEOL Ltd.).

<Elemental Analysis>

The measurement was carried out using a model G2350A from Yokogawa Furetsuto Parka Co., Ltd.

<Peng-Robinson equation calculation>

Use Aspen Plus Ver.11.1 (manufactured by Aspen Technology). The critical temperature, critical pressure, and eccentricity factor of each monomer all use the values stored in the software.

T _c : VdF 29.65°C,

TFE 33.3°C,

HFP 85.0℃

P _c : VdF 4.46MPa/SQCM,

TFE 3.94MPa/SQCM,

      HFP  3.21MPa/SQCM

ω: VdF 0.136,

TFE 0.226,

HFP 0.382

Reference example 1

(polymerization of seed polymer particles)

In a polymerization tank having an electromagnetic induction stirring device as a stirring device with an internal volume of 1.8 liters, add 720 g of pure water, 290 g of 10% by weight of ammonium perfluorooctanoate aqueous solution and 0.6 g of diethyl malonate, and fully replace the system with nitrogen To decompress. This operation was repeated 3 times, 20 g of VdF and 51 g of HFP were added under reduced pressure, and the temperature was raised to 80° C. while stirring. Next, 0.02 g of ammonium persulfate (APS) dissolved in 0.6 g of pure water was blown in with nitrogen to start polymerization. The polymerization pressure was set at 2 MPa, and VdF/HFP mixed monomer (78/22 (mol %)) was continuously supplied to compensate for the pressure drop during polymerization, and the polymerization was carried out under stirring. Until the end of the polymerization, 215 g of monomers were supplied into the tank.

The weight of the obtained emulsion was 1233 g, the polymer concentration was 18.1% by weight, and the number of polymer particles was 1.2×10 ¹⁶ per 1 g of water. After 30 minutes, the stirring was stopped, the monomer was released, and the polymerization was stopped.

Reference example 2

(Aggregation of Seed Aggregation Particles)

In a polymerization tank having an electromagnetic induction stirring device as a stirring device with an internal volume of 1.8 liters, add 809 g of pure water and 200 g of 10% by weight of ammonium perfluorooctanoate in water, and decompress after fully replacing the system with nitrogen. Repeat this operation 3 times, add 0.5mL isopentane under reduced pressure, and then add each monomer, so that the phase composition at 80°C is VdF/TFE/HFP=29.0/13.0/58.0 mol%, and the pressure in the tank is 1.4MPa. After the completion of the temperature rise, 0.67 g of ammonium persulfate (APS) dissolved in 20 g of pure water was injected with nitrogen pressure to start polymerization. The polymerization pressure was set at 1.4 MPa, and VdF/TFE/HFP mixed monomer (50/20/30 (mol %)) was continuously supplied to compensate for pressure drop during polymerization, and polymerization was carried out under stirring. Until the end of the polymerization, 320 g of the monomer was supplied into the tank.

The weight of the obtained emulsion was 1285 g, the polymer concentration was 24.8% by weight, and the number of polymer particles was 1.0×10 ¹⁵ per 1 g of water. After 360 minutes, the stirring was stopped, the monomer was released, and the polymerization was stopped.

Example 1

Add 1324g of pure water, 33.5g of the aqueous dispersion of polymer particles produced in Reference Example 1 and 19.1g of 10% by weight of the polymerization tank having the same electromagnetic induction stirring device as Reference Example 1 with an inner volume of 2.5 liters. The aqueous solution of ammonium perfluorooctanoate was decompressed after fully replacing the inside of the system with nitrogen. This operation was repeated three times, 171 g of VdF and 729 g of HFP were added under reduced pressure, and the temperature was raised to 80° C. while stirring. Next, 2.98 g of octafluoro-1,4-diiodobutane and 0.068 g of APS dissolved in 15 g of pure water were injected with nitrogen pressure to initiate polymerization and continue under the conditions of (a), (b) and (c) The polymerization was carried out, and after 4.3 hours, the stirring was stopped, the monomer was released, and the polymerization was stopped.

(a) Use Aspen Plus Ver.11.1 to calculate the critical temperature and critical pressure through the Peng-Robinson equation for the composition VdF/HFP=36/64 (mol%) in the polymerization tank, and the results are T _c =87.7°C, P _c =3.05 MPa. Furthermore, when the converted temperature T _R is 0.95 and the converted pressure P _R is 0.80, T=69.7°C and P=2.44 MPa. The polymerization conditions in this example are greater than or equal to the converted temperature and greater than or equal to the converted pressure.

(b) A monomer mixture of VdF/HFP (95/5 (mol %)) was supplied continuously, and the pressure of the gas phase was maintained at 6 MPa. Then, until the polymerization was completed, 302 g of monomers were supplied into the tank.

(c) Maintain the stirring speed at 560 rpm.

(d) When the polymerization time exceeds 3 hours, 0.034 g of APS dissolved in 15 g of pure water is added.

The weight of the obtained emulsion was 1879 g, the polymer concentration was 29.6% by weight, and the number of polymer particles was 2.7×10 ¹⁴ per 1 g of water. In addition, the amount of the fluorine-containing elastomer was 566 g, the weight average molecular weight Mw measured by GPC was 236,000, the number average molecular weight Mn was 113,000, and Mw/Mn was 2.1. The composition of the polymer measured by ¹⁹ F-NMR was VdF/HFP=77/23 (mol%).

Example 2

A fluorine-containing elastomer was polymerized in the same manner as in Example 1 except that the APS was 0.17 g.

The polymerization time was 1.5 hours, the weight of the obtained emulsion was 1909 g, the polymer concentration was 30.1% by weight, and the number of polymer particles was 2.9×10 ¹⁴ per 1 g of water. In addition, the amount of the fluoroelastomer was 575 g, the weight average molecular weight Mw measured by GPC was 277,000, the number average molecular weight Mn was 103,000, and Mw/Mn was 2.7. The composition of the polymer measured by ¹⁹ F-NMR was VdF/HFP=76/24 (mol%).

Example 3

A fluorine-containing elastomer was polymerized in the same manner as in Example 1 except that octafluoro-1,4-diiodobutane was used in an amount of 5.96 g.

The polymerization time was 3.4 hours, the weight of the obtained emulsion was 1899 g, the polymer concentration was 28.6% by weight, and the number of polymer particles was 2.6×10 ¹⁴ per 1 g of water. In addition, the amount of the fluoroelastomer was 543 g, the weight average molecular weight Mw measured by GPC was 105,000, the number average molecular weight Mn was 56,300, and Mw/Mn was 1.9. The composition of the polymer measured by ¹⁹ F-NMR was VdF/HFP=77/23 (mol%).

Comparative example 1

Add 1324g of pure water, 33.5g of the aqueous dispersion of polymer particles produced in Reference Example 1 and 19.1g of 10% by weight of the polymerization tank having the same electromagnetic induction stirring device as Reference Example 1 with an inner volume of 2.5 liters. The aqueous solution of ammonium perfluorooctanoate was decompressed after fully replacing the inside of the system with nitrogen. This operation was repeated 3 times, 20 g of VdF and 57 g of HFP were added under reduced pressure, and the temperature was raised to 80° C. while stirring. Then, 2.98g of octafluoro-1,4-diiodobutane and 0.068g of APS dissolved in 15g of pure water were injected with nitrogen pressure to initiate polymerization. In (a), (b), (c) and (d) Continue to carry out polymerization under the condition of condition, stop stirring after 16.5 hours, release monomer, stop polymerization.

(a) Use Aspen Plus Ver.11.1 to calculate the critical temperature and critical pressure through the Peng-Robinson equation for the composition VdF/HFP=50/50 (mol%) in the polymerization tank, and the results are T _c =57.3°C, P _c =3.83 MPa. Furthermore, when converted by the converted temperature TR _0.95 and the converted pressure P _R 0.80, T=40.8°C, P=3.06 MPa, and the polymerization conditions of this comparative example are greater than or equal to the converted temperature and less than or equal to the converted pressure.

(b) A monomer mixture of VdF/HFP (78/22 (mol %)) was supplied continuously, and the pressure of the gas phase was maintained at 1.5 MPa. Then, until the polymerization was completed, 570 g of monomers were supplied into the tank.

(c) Maintain the stirring speed at 560 rpm.

(d) Polymerization time 0.034 g of APS dissolved in 15 g of pure water was added every 3 hours.

The weight of the obtained emulsion was 2087 g, the polymer concentration was 27.7% by weight, and the number of polymer particles was 1.4×10 ¹⁴ per 1 g of water. In addition, the amount of the fluorine-containing elastomer was 578 g, the weight average molecular weight Mw measured by GPC was 183,000, the number average molecular weight Mn was 133,000, and Mw/Mn was 1.4. The composition of the polymer measured by ¹⁹ F-NMR was VdF/HFP=77.3/22.7 (mol%).

Embodiment 4～6 and comparative example 2

Fluorine-containing molded articles were obtained using the fluorine-containing elastomers obtained in Examples 1 to 3 and Comparative Example 1 in accordance with the following compounding and vulcanization conditions. The evaluation results are shown in Table 1.

(standard fit)

Fluorine-containing elastomer 100 parts by weight

Triallyl isocyanurate (TAIC) 4 parts by weight

パ一ヘキサ25B 1.5 parts by weight

Carbon black MT-C 20 parts by weight

(Standard Vulcanization Conditions)

Mixing method: roller mixing

Press vulcanization: 10 minutes at 160°C

Baking vulcanization: 4 hours at 180°C

Table 1

Example 7

970 g of pure water and 27 g of the aqueous dispersion of polymer particles produced in Reference Example 2 were added to a polymerization tank with an inner volume of 1.8 liters having the same electromagnetic induction stirring device as in Reference Example 1, and the system was fully replaced with nitrogen. To decompress. This operation was repeated 3 times, 18g VdF, 22g TFE, 537g HFP were added under reduced pressure, and the temperature was raised to 80°C under stirring. Next, 2.8 g of octafluoro-1,4-diiodobutane and 0.05 g of APS dissolved in 15 g of pure water were injected with nitrogen pressure to initiate polymerization, and continued under the conditions of (a), (b) and (c) The polymerization was carried out, and the stirring was stopped after 3.6 hours, and the monomer was released to stop the polymerization.

(a) Use Aspen Plus Ver.11.1 to calculate the critical temperature and critical pressure through the Peng-Robinson equation for the composition VdF/TFE/HFP=6.5/5.0/88.5 (mol%) in the polymerization tank, and the result is _Tc =87.7°C, P _c =3.05 MPa. Furthermore, when the converted temperature T _R is 0.95 and the converted pressure P _R is 0.80, T=69.7°C and P=2.44 MPa. The polymerization conditions in this example are greater than or equal to the converted temperature and greater than or equal to the converted pressure.

(b) A monomer mixture of VdF/TFE/HFP (68.0/23.8/8.2 (mol %)) was continuously supplied to maintain the pressure of the gas phase at 3.5 MPa. Then, until the polymerization was completed, 247 g of monomers were supplied into the tank.

(c) Maintain the stirring speed at 560 rpm.

The weight of the obtained emulsion was 1368 g, the polymer concentration was 26.8% by weight, and the number of polymer particles was 9.5×10 ¹⁴ per 1 g of water. In addition, the amount of the fluorine-containing elastomer was 369 g, the weight average molecular weight Mw measured by GPC was 67,000, the number average molecular weight Mn was 48,000, and Mw/Mn was 1.4. The composition of the polymer measured by ¹⁹ F-NMR was VdF/TFE/HFP=50.7/19.5/29.8 (mol%).

Example 8

A fluorine-containing elastomer was polymerized in the same manner as in Example 7 except that octafluoro-1,4-diiodobutane was used as 2.4 g.

The polymerization time was 4.2 hours, the weight of the obtained emulsion was 1401 g, the polymer concentration was 28.6% by weight, and the number of polymer particles was 3.5×10 ¹⁴ per 1 g of water. In addition, the amount of the fluorine-containing elastomer was 396 g, the weight average molecular weight Mw measured by GPC was 87,000, the number average molecular weight Mn was 57,000, and Mw/Mn was 1.5. The composition of the polymer measured by ¹⁹ F-NMR was VdF/TFE/HFP=51.0/19.8/29.2 (mol%).

Example 9

Except for the following (a), (b) and (c), the fluoroelastomer was polymerized in the same manner as in Example 7: (a) adding 2.4 g of octafluoro-1,4-diiodobutane, (b) 3.96 g of CF ₂ =CFOCF ₂ CF ₂ CH ₂ I was added when 50% of the monomer amount was added. (c) 0.025 g of APS dissolved in 15 g of pure water was added every 3 hours during the polymerization time.

The polymerization time was 3.8 hours, the weight of the obtained emulsion was 1391 g, the polymer concentration was 27.3% by weight, and the number of polymer particles was 8.3×10 ¹⁴ per 1 g of water. In addition, the amount of the fluorine-containing elastomer was 384 g, the weight average molecular weight Mw measured by GPC was 92,000, the number average molecular weight Mn was 59,000, and Mw/Mn was 1.6. The composition of the polymer measured by ¹⁹ F-NMR was VdF/TFE/HFP=52.0/20.7/27.3 (mol%).

Comparative example 3

970 g of pure water and 27 g of the aqueous dispersion of polymer particles produced in Reference Example 2 were added to a polymerization tank with an inner volume of 1.83 liters of the same electromagnetic induction stirring device as in Reference Example 7, and the system was fully replaced with nitrogen. To decompress. This operation was repeated three times, and each monomer was added under reduced pressure so that the composition in the tank at 80° C. was VdF/TFE/HFP=11.0/19.0/70.0 (mol %), and the tank pressure was 1.5 MPa. Next, inject 1.7g of octafluoro-1,4-diiodobutane and 0.05g of APS dissolved in 15g of pure water with nitrogen pressure to initiate polymerization, and continue polymerization under the conditions of (a) to (d), 15.3 After 1 hour, the stirring was stopped, and the monomer was released to stop the polymerization.

(a) Use Aspen Plus Ver.11.1 to calculate the critical temperature and critical pressure through the Peng-Robinson equation for the composition VdF/TFE/HFP=11/19/70 (mol%) in the polymerization tank, and the result is T _c =69.0°C, P _c =3.48 MPa. Furthermore, when the converted temperature T _R is 0.95 and the converted pressure P _R is 0.80, T = 51.9°C and P = 2.78 MPa. The polymerization conditions in this example are greater than or equal to the converted temperature and less than or equal to the converted pressure.

(b) A monomer mixture of VdF/TFE/HFP (50.0/20.0/30.0 (mol %)) was supplied continuously, and the pressure of the gas phase was maintained at 1.5 MPa. Then, until the polymerization was completed, 370 g of monomers were supplied into the tank.

(c) Maintain the stirring speed at 560 rpm.

(d) Polymerization time 0.025 g of APS dissolved in 15 g of pure water was added every 3 hours.

The weight of the obtained emulsion was 1410 g, the polymer concentration was 26.2% by weight, and the number of polymer particles was 3.9×10 ¹⁴ per 1 g of water. In addition, the amount of the fluorine-containing elastomer was 370 g, the weight average molecular weight Mw measured by GPC was 85,000, the number average molecular weight Mn was 61,000, and Mw/Mn was 1.4. The composition of the polymer measured by ¹⁹ F-NMR was VdF/TFE/HFP=50.2/19.8/30.0 (mol%).

Examples 10-12 and Comparative Example 4

Fluorine-containing molded articles were obtained using the fluorine-containing elastomers obtained in Examples 7 to 9 and Comparative Example 3 in accordance with the following compounding and vulcanization conditions. The evaluation results are shown in Table 2.

(standard fit)

Fluoroelastomer 100 parts by weight

Triallyl isocyanurate (TAIC) 4 parts by weight

パ一キサ25B 1.5 parts by weight

Carbon black MT-C 20 parts by weight

(Standard Vulcanization Conditions)

Mixing method: roller mixing

Press vulcanization: 10 minutes at 160°C

Baking vulcanization: 4 hours at 180°C

Table 2

Possibility of industrial use

The present invention provides a method for producing a fluoroelastomer by carrying out iodine transfer polymerization under high pressure, in which the polymerization rate is greatly increased despite a small amount of polymerization initiator, and has a high efficiency comparable to non-iodine transfer polymerization. productivity. Furthermore, the elastomer produced by this method has few branched chains and a high content of terminal iodine atoms, and also provides a fluorine-containing elastomer and a fluorine-containing molded article having an excellent balance between compression set and tensile elongation at break.

Claims (3)

1. fluoroelastomer, described fluoroelastomer contains the vinylidene fluoride repeating unit of 20 moles of %～90 mole %, the R 1216 repeating unit of 10 moles of %～80 mole %, wherein, (a) in elastomerics, contain the iodine atom of 0.05 weight %～2.0 weight %, (b) the polymkeric substance number-average molecular weight is 1,000～300,000, (c) use high resolving power ¹⁹F-NMR measures the acetone soln of polymer concentration about 20%, by following formula

" the VdF branching rate " of trying to achieve is that described fluorine-containing resilient energy is carried out peroxide cure smaller or equal to 200ppm,

Wherein, the iodine atomic linkage is on the end carbon of polymkeric substance.

2. fluoroelastomer as claimed in claim 1, wherein, the tension fracture elongation rate Eb of the formed body that obtains of sulfuration is 200%～550%, and is 5%～30% at 200 ℃, 72 hours compression set CS.

3. composition is used in fluoroelastomer curing, and it contains claim 1 or 2 described fluoroelastomer and vulcanizing agents.