JP2012246498A - Method for manufacturing fluorine-containing elastomer and fluorine-elastomer manufacturing by the same metod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a fluorine-containing elastomer excellent in properties such as compression set, heat resistance and stress relaxation by limiting the time for adding a specific CSM, and to provide a fluorine-containing elastomer and its moldings manufactured by this method.SOLUTION: The manufacturing method is a method for manufacturing a fluorine-containing elastomer by copolymerizing an ethylenically unsaturated compound containing at least one kind of fluoroolefines, and a compound expressed by general fomula (1) CY= CYRX(wherein, Y, Yare a fluorine atom, a hydrogen atom or -CH; Ris a straight chain or a branching fluorine-containing alkylene group which may contain an ether bonding oxygen atom and part or all of hydrogen atom and which are substituted with a fluorine atom, and Xis iodine atoms or bromine atoms ), and is characterized by starting of addition of the compound expressed by general formula (1) when 0-10 wt. of the total amount of the ethylenically unsaturated compound is added into a polymerization system after addition of a polymerization initiator.

Description

The present invention relates to a method for producing a fluorine-containing elastomer using a specific cure site monomer (hereinafter referred to as CSM). Furthermore, the present invention relates to a fluorine-containing elastomer produced by this method, and a molded article excellent in compression set resistance, heat resistance and stress relaxation behavior obtained by crosslinking the fluorine-containing elastomer.

Since vinylidene fluoride-hexafluoropropylene (VdF-HFP) -based and tetrafluoroethylene (TFE) -perfluorovinyl ether-based fluorine-containing elastomers exhibit their outstanding chemical resistance, solvent resistance, and heat resistance, O-rings, gaskets, hoses, stem seals, shaft seals, diaphragms and the like used in harsh environments are widely used in fields such as the automobile industry, semiconductor industry, and chemical industry.

As a fluorine-containing elastomer used for such applications, there is a fluorine-containing elastomer having a crosslinking site such as a highly active iodine atom at the molecular end. The fluorine-containing elastomer having a crosslinking site at the molecular end can have good crosslinking efficiency due to the crosslinking site at the molecular end and is excellent in crosslinkability. Further, since it is not necessary to add a chemical substance having a metal component, it is widely used as a peroxide vulcanized product.

Peroxide vulcanization systems (for example, see JP-A-53-125491) are excellent in chemical resistance and steam (hot water) resistance, but their compression set resistance is higher than that of polyol vulcanization systems. It was inferior. This problem has been solved by introducing a crosslinking site into the elastomer main chain (see, for example, JP-A-62-12734). However, further improvements are desired in that both compression set and tensile elongation at break are balanced.

As a method of introducing a crosslinking site, a method of copolymerizing a CSM having a crosslinking site, a method of producing by an emulsion polymerization method such as a so-called iodine transfer polymerization method (see, for example, Japanese Patent Publication No. 63-41928) is proposed. Has been. However, in the iodine transfer polymerization method, in order to achieve a high terminal iodination rate, it is necessary to suppress the amount of polymerization initiator used (for example, Masayoshi Kenmoto P19, 86/6 Microsymposium, Polymers in radical polymerization). There was a problem that the productivity could not be increased by that much, see Structural Regulation, Polymer Society (1986)). In polymerization systems where there is no restriction on the amount of polymerization initiator used, it is possible to easily increase the polymerization rate by increasing the amount of initiator, but in iodine transfer polymerization systems, the initiator end concentration is large in the physical properties of the final product. It is not possible to increase the amount of initiator used due to the influence.

In order to solve these problems, it has been proposed to produce iodine transfer polymerization by a two-stage emulsion polymerization method (see, for example, International Publication No. 00/01741 pamphlet). In the two-stage emulsion polymerization, a large amount of emulsifier is used in the first stage polymerization to synthesize a large number of polymer particles, and then the obtained emulsion is diluted to lower the polymer particle concentration and the emulsifier concentration. This is a method of performing the second stage polymerization using this diluted emulsion. In this method, the polymerization rate can be shortened more than twice while maintaining the original characteristics with a uniform particle size without greatly changing the equipment for emulsion polymerization so far, but the productivity is still inferior. It was something.

Further, when CSM is used, if the amount added is increased, the crosslink density is increased, so that heat resistance and compression set are excellent, but physical properties such as tensile elongation at break decrease.

In U.S. Pat. No. 6,664,077, which is a production method using CSM, a chain transfer agent represented by RI _x is added during the polymerization when the amount of the monomer added is 0 to 50%. There has been proposed a method for producing a fluorine-containing elastomer in which addition of CSM is started when the addition amount of the monomer to be added is 10 to 90%. However, when the addition start is performed with the addition amount of less than 10% of the additional monomer, the polymerization hardly progresses or the polymerization is stopped. Further, the fluorine-containing monomer obtained by this method has a problem that the improvement in performance having both compression set and tensile elongation at break is not sufficient because the addition time of CSM is restricted.

The present invention provides a fluorine-containing elastomer that can be made into a molded article having excellent physical properties such as compression set, tensile elongation at break, heat resistance, stress relaxation, etc. by limiting the timing of starting the addition of a specific CSM. Provide a method. Furthermore, a fluorine-containing elastomer produced by this method, a composition containing the fluorine-containing elastomer, and a molded product obtained by crosslinking the composition are provided.

That is, the present invention relates to an ethylenically unsaturated compound containing at least one fluoroolefin and a general formula (1):
CY ¹ ₂ = CY ² R _f ¹ X ¹ (1)
(Wherein Y ¹ and Y ² are fluorine atoms, hydrogen atoms or —CH ₃ ; R _f ¹ may have an etheric oxygen atom, and part or all of the hydrogen atoms are substituted with fluorine atoms. A linear or branched fluorine-containing alkylene group; X ¹ is an iodine atom or a bromine atom)
A method for producing a fluorine-containing elastomer, which is copolymerized with a compound represented by
Addition of the compound represented by the general formula (1) is added to (added to) the polymerization system after addition of the polymerization initiator (after the start of polymerization). The present invention relates to a method for producing a fluorine-containing elastomer, which is characterized by starting at the time when wt% is added.

The addition of the compound represented by the general formula (1) is added to (added to) the polymerization system after the addition of the polymerization initiator (after the start of the polymerization). It is preferable to end at the time when% is added.

The compound represented by the general formula (1) is
CF ₂ = CFOCF ₂ CF ₂ CH ₂ I
It is preferable that

The fluoroolefin is represented by the general formula (2):
CX ² X ³ = CX ⁴ X ⁵ (2)
(X ^{2 to} X ⁴ are a hydrogen atom or a halogen atom; X ⁵ contains a hydrogen atom, a halogen atom, a carboxyl group, or an ether-bonded oxygen atom in which some or all of the hydrogen atoms are substituted with fluorine atoms. A fluorine-containing alkyl group having 1 to 9 carbon atoms, or a fluorine-containing alkoxy group having 1 to 9 carbon atoms which may contain an ether-bonded oxygen atom in which part or all of the hydrogen atoms are substituted with fluorine atoms; (However, at least one of X ^{2 to} X ⁵ is a fluorine atom, a fluorine-containing alkyl group or a fluorine-containing alkoxy group)
It is preferable that it is a compound shown by these.

（式中Ｙ^３は、−ＣＨ_２Ｉ、−ＯＨ、−ＣＯＯＨ、−ＳＯ_２Ｆ、−ＳＯ_３Ｍ（Ｍは水素原子、ＮＨ_４またはアルカリ金属原子）、カルボン酸塩、カルボキシエステル基、エポキシ基、シアノ基、ヨウ素原子；Ｘ^６およびＸ^７は同じかまたは異なりいずれも水素原子またはフッ素原子；Ｒ_ｆ ^２はエーテル結合性酸素原子を含んでもよい炭素数１〜４０の２価の含フッ素アルキレン基；ｎは０または１；ただし、前記一般式（１）と同一のものは除く）
からなる群から選択された化合物を含むことが好ましい。 The fluoroolefin is hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, pentafluoropropylene, vinyl fluoride, hexafluoroisobutene, perfluoro (alkyl vinyl ether) s, polyfluorodienes, and general formula (3):

Wherein Y ³ is —CH ₂ I, —OH, —COOH, —SO ₂ F, —SO ₃ M (M is a hydrogen atom, NH ₄ or an alkali metal atom), carboxylate, carboxyester group, epoxy A group, a cyano group, an iodine atom; X ⁶ and X ⁷ are the same or different and each is a hydrogen atom or a fluorine atom; R _f ² may contain an ether-bonded oxygen atom; Alkylene group; n is 0 or 1; provided that the same as the above general formula (1) is excluded)
Preferably it comprises a compound selected from the group consisting of

Moreover, this invention relates to the fluorine-containing elastomer obtained by the said manufacturing method.

Furthermore, the present invention relates to a crosslinkable composition containing the fluorine-containing elastomer and a molded product obtained by crosslinking the crosslinkable composition.

Furthermore, the present invention provides an ethylenically unsaturated compound containing at least one fluoroolefin, and a general formula (1):
CY ¹ ₂ = CY ² R _f ¹ X ¹ (1)
(Wherein Y ¹ and Y ² are fluorine atoms, hydrogen atoms or —CH ₃ ; R _f ¹ may have an etheric oxygen atom, and part or all of the hydrogen atoms are substituted with fluorine atoms. A linear or branched fluorine-containing alkylene group; X ¹ is an iodine atom or a bromine atom)
In a Mark-Houwink plot in which the absolute weight molecular weight and intrinsic viscosity are absolute weight molecular weight and the vertical axis is intrinsic viscosity. The present invention also relates to a novel fluorine-containing elastomer having a Mark-Howin gradient a as plotted of 0.46 or less.

2 is a Mark-Houwin plot of fluorine-containing elastomers obtained in Example 1, Example 2 and Comparative Example 1. FIG. It is shown that the Mark-Howin gradient a is 0.46 or less in Examples 1 and 2 and exceeds 0.46 in Comparative Example 1.

The present invention relates to an ethylenically unsaturated compound containing at least one fluoroolefin and a general formula (1):
CY ¹ ₂ = CY ² R _f ¹ X ¹ (1)
(Wherein Y ¹ and Y ² are fluorine atoms, hydrogen atoms or —CH ₃ ; R _f ¹ may have an etheric oxygen atom, and part or all of the hydrogen atoms are substituted with fluorine atoms. A linear or branched fluorine-containing alkylene group; X ¹ is an iodine atom or a bromine atom)
A method for producing a fluorine-containing elastomer, which is copolymerized with a compound represented by
Addition of the compound represented by the general formula (1) to the polymerization system after addition of the polymerization initiator is added to the polymerization system, that is, the polymerization system is started after the polymerization initiator is added to start the polymerization. A method for producing a fluorine-containing elastomer, characterized by starting at a time when 0 to 10% by weight of the total amount of the ethylenically unsaturated compound to be additionally introduced (hereinafter referred to as “total additional amount”) is added (added) About.

In the production method of the present invention, the addition of the compound represented by the general formula (1) is started at a time when 0 to 10% by weight of the total additional amount of the ethylenically unsaturated compound is added. Since the molecular lengths of the chains are almost the same and the distribution of the distance between the cross-linking points is uniform, it is possible to produce a fluorine-containing elastomer that can obtain a molded product having excellent compression set, heat resistance, and tensile elongation at break. .

In the present invention, the addition of the compound represented by the general formula (1) is started when 0 to 10% by weight of the total additional amount of the ethylenically unsaturated compound is added, preferably 0 to 8 It is a time when the weight% is added, more preferably 0-5% by weight. If the addition starts at a time exceeding 10% by weight of the total amount of the ethylenically unsaturated compound, only the main chain molecules grow first, and the main chain and side chain molecular lengths are uneven. Thus, the uniformity of the distribution of the distance between the crosslinking points tends to be reduced. Here, starting at the time when 0% by weight of the total additional amount of the ethylenically unsaturated compound is added means that the compound represented by the general formula (1) is added in advance before the addition of the polymerization initiator or the polymerization initiator. Is added to the polymerization system after the start of polymerization and before the addition of the ethylenically unsaturated compound, and then the addition of the ethylenically unsaturated compound is started. It is particularly preferable to start adding the compound represented by the general formula (1) simultaneously with the addition of the polymerization initiator (at the time of 0% by weight of the total additional amount).

The method for adding the compound represented by the general formula (1) is not particularly limited, and it may be added in several batches such as batch addition, bisection, trisection, or continuous addition. Good.

Although the end time of the addition of the compound represented by the general formula (1) is not particularly limited, it is preferable to add 0 to 20% by weight of the total additional amount of the ethylenically unsaturated compound. More preferably, 0-10% by weight is added. If it is after the addition of 20% by weight, only the main chain molecules are growing, and the uniformity of the distribution of the distance between the crosslinking points tends to be lowered. Here, the term “finished when 0% by weight of the total additional amount of the ethylenically unsaturated compound is added” means that the compound represented by the general formula (1) is added in advance or before the polymerization initiator is added. Simultaneously with the addition of the above, and further, after the start of polymerization and before the addition of the ethylenically unsaturated compound, it is supplied all at once to the polymerization system, and then the addition of the ethylenically unsaturated compound is started.

Here, in the production method of the present invention, usually, the ethylenically unsaturated compound is charged into a polymerization system in advance, and a polymerization initiator is added to start the polymerization. A method of continuing the polymerization by adding the compound represented by the formula (1) can be employed. The method for adding the ethylenically unsaturated compound is not particularly limited, and the ethylenically unsaturated compound may be added in several batches such as batch addition, bisection, and trisection, or may be added continuously.

In addition, a more specific polymerization method will be described later on behalf of the iodine transfer polymerization method.

The addition amount of the compound represented by the general formula (1) is preferably 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the fluorine-containing elastomer, and 0.5 to 1.5 parts by weight. More preferably.

General formula (1) used in the present invention:
CY ¹ ₂ = CY ² R _f ¹ X ¹ (1)
(Wherein Y ¹ and Y ² are fluorine atoms, hydrogen atoms or —CH ₃ ; R _f ¹ may have an etheric oxygen atom, and part or all of the hydrogen atoms are substituted with fluorine atoms. A linear or branched fluorine-containing alkylene group; X ¹ is an iodine atom or a bromine atom)
Examples of the compound represented by general formula (4):
CY ¹ ₂ = CY ² R _f ³ CHR ¹ -X ¹ (4)
(In the formula, Y ¹ , Y ² and X ¹ are the same as described above, and R _f ³ may have one or more ether type oxygen atoms, and part or all of the hydrogen atoms are substituted with fluorine atoms. A linear or branched fluorine-containing alkylene group, that is, a linear or branched fluorine-containing alkylene group in which part or all of the hydrogen atoms are substituted with fluorine atoms, or part or all of the hydrogen atoms are A linear or branched fluorine-containing oxyalkylene group substituted with a fluorine atom, or a linear or branched fluorine-containing polyoxyalkylene group in which some or all of the hydrogen atoms are substituted with fluorine atoms; R ¹ is a hydrogen atom or a methyl group)
Iodine-containing monomer, bromine-containing monomer represented by general formulas (5) to (22):
CY ⁴ ₂ = CY ⁴ (CF ₂ ) _n -X ¹ (5)
(Wherein Y ⁴ is a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8)
^{_{CF 2 = CFCF 2 R f 4}} -X 1 (6)
(Where

And n is an integer from 0 to 5)
CF ₂ = CFCF ₂ (OCF (CF ₃ ) CF ₂ ) _{m
(OCH 2 CF 2 CF 2)} n OCH 2 CF 2 -X 1 (7)
(In the formula, m is an integer of 0 to 5, n is an integer of 0 to 5)
CF ₂ = CFCF ₂ (OCH ₂ CF ₂ CF ₂ ) _{m
(OCF (CF 3) CF 2} ) n OCF (CF 3) -X 1 (8)
(In the formula, m is an integer of 0 to 5, n is an integer of 0 to 5)
_{CF 2 = CF (OCF 2 CF} (CF 3)) m O (CF 2) n -X 1 (9)
(Wherein, m is an integer from 0 to 5, and n is an integer from 1 to 8)
_{CF 2 = CF (OCF 2 CF} (CF 3)) m -X 1 (10)
(Where m is an integer from 1 to 5)
CF ₂ = CFOCF ₂ (CF (CF ₃ ) OCF ₂ ) _n CF (−X ¹ ) CF ₃ (11)
(Where n is an integer from 1 to 4)
_{CF 2 = CFO (CF 2)} n OCF (CF 3) -X 1 (12)
(Where n is an integer from 2 to 5)
_{CF 2 = CFO (CF 2)} n - (C 6 H 4) -X 1 (13)
(Where n is an integer from 1 to 6)
_{CF 2 = CF (OCF 2 CF} (CF 3)) n OCF 2 CF (CF 3) -X 1 (14)
(Where n is an integer from 1 to 2)
_{CH 2 = CFCF 2 O (CF} (CF 3) CF 2 O) n CF (CF 3) -X 1 (15)
(Where n is an integer from 0 to 5),
_{CF 2 = CFO (CF 2 CF} (CF 3) O) m (CF 2) n -X 1 (16)
(In the formula, m is an integer of 0 to 5, n is an integer of 1 to 3)
_{CH 2 = CFCF 2 OCF (CF} 3) OCF (CF 3) -X 1 (17)
_{CH 2 = CFCF 2 OCH 2 CF} 2 -X 1 (18)
_{CF 2 = CFO (CF 2 CF} (CF 3) O) m CF 2 CF (CF 3) -X 1 (19)
(Where m is an integer of 0 or more)
_{CF 2 = CFOCF (CF 3)} CF 2 O (CF 2) n -X 1 (20)
(Where n is an integer of 1 or more)
_{CF 2 = CFOCF 2 OCF 2 CF} (CF 3) OCF 2 -X 1 (21)
^{_{CH 2 = CH- (CF 2)}} n X 1 (22)
(Where n is an integer from 2 to 8)
(In the general formulas (5) to (22), X ¹ is the same as above)
These include iodine-containing monomers, bromine-containing monomers, and the like, and these can be used alone or in any combination.

As the iodine-containing monomer or bromine-containing monomer represented by the general formula (4), the general formula (23):

(In the formula, m is an integer of 1 to 5, and n is an integer of 0 to 3).
Preferred is an iodine-containing fluorinated vinyl ether represented by:

Among them, ICH ₂ CF ₂ CF ₂ OCF═CF ₂ is preferable among these.

More specifically, the iodine-containing monomer or bromine-containing monomer represented by the general formula (5) is preferably ICF ₂ CF ₂ CF═CH ₂ or I (CF ₂ CF ₂ ) ₂ CF═CH _2. It is done.

More specifically, the iodine-containing monomer or bromine-containing monomer represented by the general formula (9) is preferably I (CF ₂ CF ₂ ) ₂ OCF═CF ₂ .

As More specifically iodine-containing monomer or bromine-containing monomer represented by the general formula _{(22), CH 2 = CHCF} 2 CF 2 I, I (CF 2 CF 2) 2 CH = CH 2 is exemplified preferably It is done.

In addition, X ¹ of the compounds represented by the general formulas (4) to (22) is a cyano group (—CN group), a carboxyl group (—COOH group), or an alkoxycarbonyl group (—COOR group, where R is 1 to A monomer changed to an alkyl group which may contain 10 fluorine atoms) may be used together with the compound represented by the general formula (1).

Although it does not specifically limit as a manufacturing method of this invention, It is preferable that it is an iodine transfer polymerization method from the point that it is comparatively easy to closely approach distribution of the distance between bridge | crosslinking points.

Hereinafter, although iodine transfer polymerization is demonstrated, it is not limited to this method.

The reaction vessel used in the present invention is preferably a pressure vessel when polymerization is carried out under pressure, and the reaction vessel is not particularly limited unless it is under high pressure, and a reaction vessel used during normal elastomer production. Can be used. An aqueous medium (usually pure water) containing polymer particles having the same composition as the target polymer for emulsion polymerization (fluorine-containing elastomer) is placed in this reaction tank to form a liquid phase portion.

The reaction tank is composed of a liquid phase portion and a gas phase portion. After the gas phase portion is replaced with nitrogen or the like, a polymerizable monomer (ethylenically unsaturated compound) is introduced. Next, the polymerizable monomer is supplied from the gas phase portion to the liquid phase portion by stirring the inside of the reaction vessel, particularly the liquid phase portion. The monomer supplied to the liquid phase part penetrates into the polymer particles and raises the concentration of the polymerizable monomer in the polymer particles. By continuously supplying the monomer to the gas phase part, the monomer concentration in the polymer particles becomes saturated (it can be said that the monomer supply rate to the liquid phase part is in an equilibrium state), so the polymerization initiator and iodine compound are added. To start the polymerization.

As the polymerization is continued, the monomer is consumed and the monomer concentration in the produced polymer particles decreases, so the monomer (additional monomer) is always supplied into the polymer particles.

The ratio of the additional monomer depends on the composition of the added monomer and the target polymer, but is preferably a ratio that keeps the monomer composition in the reaction vessel at the initial stage of polymerization constant.

Moreover, in this invention, addition of the compound shown by General formula (1) is added at the said time.

In the present invention, the temperature and pressure during the polymerization are not particularly limited and are appropriately selected depending on the type of monomer, the type of the compound represented by the general formula (1), and the like. The temperature is preferably 140 ° C, more preferably 30 to 100 ° C, and the polymerization pressure is preferably 0.1 to 15 MPa, more preferably 3 to 12 MPa. When the polymerization temperature is less than 10 ° C., the monomer concentration in the polymer particles does not reach saturation and the polymerization rate is lowered, and the target polymer tends to be difficult to obtain. The upper limit of the pressure is not particularly limited, but is preferably 15 MPa or less, and more preferably 12 MPa or less in consideration of handling of the monomer, reaction equipment cost, and the like. Furthermore, it is preferable to stir. This is because the monomer concentration in the polymer particles can be kept high throughout the polymerization by stirring. As a means for stirring, for example, an anchor blade, a turbine blade, an inclined blade, or the like can be used. From the viewpoint of good monomer diffusion and polymer dispersion stability, stirring with a large blade called full zone or max blend is preferable.

The stirring device may be a horizontal stirring device or a vertical stirring device.

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

As an iodine compound, general formula (24):
R _f ⁵ · I _x (24)
The iodine compound shown by these is mention | raise | lifted. In the formula, R _f ⁵ is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, and is preferably a perfluoroalkyl group having 4 to 8 carbon atoms. When the carbon number exceeds 16, the reactivity tends to decrease.

X of the iodine compound represented by the general formula (24) is the number of bonds of R _f ⁵ , is an integer of 1 to 4, and is preferably an integer of 2 to 3. Although it can be used even if x exceeds 4, it is not preferable in terms of synthesis cost.

The carbon-iodine bond of this iodine compound is a relatively weak bond and is cleaved as a radical in the presence of a radical source. Due to the high reactivity of the radicals generated, the monomer undergoes an additional growth reaction, and then the reaction is stopped by extracting iodine from the iodine compound. The fluorine-containing elastomer in which iodine is bonded to the carbon at the molecular end thus obtained can be efficiently cross-linked by the terminal iodine becoming an effective cross-linking point.

Examples of the iodine compound represented by the general formula (24) include monoiodoperfluoromethane, monoiodoperfluoroethane, monoiodoperfluoropropane, monoiodoperfluorobutane [for example, 2-iodoperfluorobutane, 1-iodoper Fluoro (1,1-dimethylethane)], monoiodoperfluoropentane [eg 1-iodopearlfluoro (4-methylbutane)], 1-iodoperfluoro-n-octane, monoiodoperfluorocyclobutane, monoiodoperfluoro Cyclohexane, monoiodotrifluorocyclobutane, monoiododifluoromethane, monoiodomonofluoromethane, 2-iodo-1-hydroperfluoroethane, 3-iodo-1-hydroperfluoropropane, monoiodo monochlorodiphenyl Oromethane, 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-iodoperfluoropropene-1, 4-iodoperfluoropentene-1, 4-iodo-5-chloroperfluoropentene-1, 2-iodoperfluoro (1-cyclobutenylethane), 1,3- Diiodoperfluoropropane, 1,4-diiodoperfluoro-n-butane, 1,3-diiodo- -Chloroperfluoropropane, 1,5-diiodo-2,4-dichloroperfluoro-n-pentane, 1,7-diiodoperfluoro-n-octane, 1,2-di (iododifluoromethyl) perfluorocyclobutane 2-iodo-1,1,1-trifluoroethane, 1-iodo-1-hydroperfluoro (2-methylethane), 2-iodo-2,2-dichloro-1,1,1-trifluoroethane, Examples include 2-iodo-2-chloro-1,1,1-trifluoroethane. Further, the hydrocarbon group of R _f ⁵ may contain a functional group such as an ether-bonded oxygen atom, a thioether-bonded sulfur atom, or a carboxyl group, such as 2-iodoperfluoro (ethyl vinyl ether), 2-iodo. Examples thereof include perfluoro (ethyl isopropyl ether), 3-iodo-2-chloroperfluoro (butylmethylthioether), 3-iodo-4-chloroperfluorobutyric acid, and the like.

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

The addition amount of the iodine compound is preferably 0.05 to 2.0% by weight with respect to the fluorine-containing elastomer. When the addition amount is less than 0.05% by weight, the crosslinking becomes insufficient and the compression set (CS) tends to deteriorate. When the addition amount exceeds 2.0% by weight, the crosslinking density increases too much. There is a tendency to impair rubber performance such as elongation.

The iodine compound may be added all at once in the initial stage of polymerization, or may be added in several times.

As the fluoroolefin used in the present invention, the general formula (2):
CX ² X ³ = CX ⁴ X ⁵ (2)
(X ^{2 to} X ⁴ are a hydrogen atom or a halogen atom; X ⁵ contains a hydrogen atom, a halogen atom, a carboxyl group, or an ether-bonded oxygen atom in which some or all of the hydrogen atoms are substituted with fluorine atoms. A fluorine-containing alkyl group having 1 to 9 carbon atoms, or a fluorine-containing alkoxy group having 1 to 9 carbon atoms which may contain an ether-bonded oxygen atom in which part or all of the hydrogen atoms are substituted with fluorine atoms; (However, at least one of X ^{2 to} X ⁵ is a fluorine atom, a fluorine-containing alkyl group or a fluorine-containing alkoxy group)
Is preferred.

Examples of the fluoroolefin represented by the general formula (2) include hexafluoropropylene (HFP), vinylidene fluoride (VdF), tetrafluoroethylene (TFE), trifluoroethylene, pentafluoropropylene, vinyl fluoride, hexafluoroisobutene, Examples include chlorotrifluoroethylene (CTFE), trifluoropropylene, pentafluoropropylene, tetrafluoropropylene, hexafluoroisobutene, and perfluoro (alkyl vinyl ether) (PAVE). From the viewpoint that an elastomer composition is easily obtained, vinylidene fluoride is used. Ride (VdF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluoro (alkyl vinyl ether) (PAVE), trifluoro Styrene, hexafluoropropylene, vinyl fluoride, hexafluoroisobutene are preferred.

Perfluoro (alkyl vinyl ethers) 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), and the like.

Moreover, as a fluoroolefin other than the fluoroolefin represented by the general formula (2),

Or a general formula (3):

（式中Ｙ^３は、−ＣＨ_２Ｉ、−ＯＨ、−ＣＯＯＨ、−ＳＯ_２Ｆ、−ＳＯ_３Ｍ（Ｍは水素原子、ＮＨ_４またはアルカリ金属原子）、カルボン酸塩、カルボキシエステル基、エポキシ基、シアノ基、ヨウ素原子；Ｘ^６およびＸ^７は同じかまたは異なりいずれも水素原子またはフッ素原子；Ｒ_ｆ ^２はエーテル結合性酸素原子を含んでもよい炭素数１〜４０の２価の含フッ素アルキレン基；ｎは０または１；ただし、前記一般式（１）と同一のものは除く）で示される官能基含有フルオロオレフィンやポリフルオロジエン類などがあげられる。

Wherein Y ³ is —CH ₂ I, —OH, —COOH, —SO ₂ F, —SO ₃ M (M is a hydrogen atom, NH ₄ or an alkali metal atom), carboxylate, carboxyester group, epoxy A group, a cyano group, an iodine atom; X ⁶ and X ⁷ are the same or different and each is a hydrogen atom or a fluorine atom; R _f ² may contain an ether-bonded oxygen atom; An alkylene group; n is 0 or 1; provided that the functional group-containing fluoroolefins and polyfluorodienes represented by the general formula (1) are excluded).

Functional group-containing fluoroolefins are preferred as functional monomers for surface modification and crosslinking density increase, and polyfluorodienes are preferred from the viewpoint of crosslinking efficiency.

As the functional group-containing fluoroolefin represented by the general formula (3),

Etc.

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

Although it does not specifically limit as ethylenically unsaturated compounds other than a fluoro olefin, C2-C10 alpha olefin monomers, such as ethylene (ET), propylene, butene, pentene, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, cyclohexyl Examples thereof include alkyl vinyl ethers having an alkyl group having 1 to 20 carbon atoms such as vinyl ether, hydroxybutyl vinyl ether and butyl vinyl ether. These are preferable in terms of low cost and amine resistance.

As a combination of monomers forming the fluorine-containing elastomer of the present invention, one or more fluoroolefins represented by the above general formula (2), one or more fluoroolefins other than the general formula (2), and general formula (2) And a combination containing at least one fluoroolefin other than the general formula (2) and an ethylenically unsaturated compound other than the fluoroolefin as a copolymerization monomer for each combination. You may go out.

Among the fluoroolefin represented by the general formula (2) and the ethylenically unsaturated compounds other than the fluoroolefin represented by the general formula (2), for the purpose of forming a fluorine-containing elastomer having good crosslinkability at low cost And an ethylenically unsaturated compound copolymerizable with vinylidene fluoride (VdF).

The production method of the present invention is suitable for producing a VdF elastomer comprising VdF and other monomers.

Specifically, in the VdF elastomer, the VdF repeating unit is 20 mol% or more and 90 mol% of the total number of moles of the VdF repeating unit and the repeating unit derived from another comonomer in the VdF elastomer. The following is preferable, and it is more preferably 40 mol% or more and 85 mol% or less. A more preferred lower limit is 45 mol%, a particularly preferred lower limit is 50 mol%, and a more preferred upper limit is 80 mol%.

The other monomer in the VdF elastomer is not particularly limited as long as it is copolymerizable with VdF. For example, TFE, HFP, PAVE, CTFE, trifluoroethylene, trifluoropropylene, tetrafluoropropylene, penta Fluorine-containing monomers such as fluoropropylene, trifluorobutene, tetrafluoroisobutene, vinyl fluoride, iodine-containing fluorinated vinyl ether; fluorine-free monomers such as ethylene (Et), propylene (Pr), alkyl vinyl ether, etc. These fluorine-containing monomers and non-fluorine-containing monomers can be used alone or in combination of two or more. As the PAVE, perfluoro (methyl vinyl ether) and perfluoro (propyl vinyl ether) are preferable, and perfluoro (methyl vinyl ether) is particularly preferable.

Examples of the VdF elastomer include VdF / HFP copolymer, VdF / HFP / TFE copolymer, VdF / CTFE copolymer, VdF / CTFE / TFE copolymer, VdF / PAVE copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, VdF / HFP / TFE / PAVE copolymer, VdF / TFE / Pr copolymer, or VdF / Et / HFP copolymer are preferred, but other More preferably, the monomer has TFE, HFP, and / or PAVE, and in particular, VdF / HFP copolymer, VdF / HFP / TFE copolymer, VdF / PAVE copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, or VdF / HFP / TFE / PAVE copolymer Coalescence is preferable.

In the VdF / HFP copolymer, the composition of VdF / HFP is preferably (45 to 85) / (55 to 15) (mol%), more preferably (50 to 80) / (50 to 20). ) (Mol%), and more preferably (60-80) / (40-80) (mol%).

The VdF / HFP / TFE copolymer preferably has a VdF / HFP / TFE composition of (40-80) / (10-35) / (10-25) (mol%).

As the VdF / PAVE copolymer, those having a composition of VdF / PAVE of (65 to 90) / (10 to 35) (mol%) are preferable.

As the VdF / TFE / PAVE copolymer, those having a composition of VdF / TFE / PAVE of (40 to 80) / (3 to 40) / (15 to 35) (mol%) are preferable.

As a VdF / HFP / PAVE copolymer, the composition of VdF / HFP / PAVE is preferably (65 to 90) / (3 to 25) / (3 to 25) (mol%).

As VdF / HFP / TFE / PAVE copolymerization, the composition of VdF / HFP / TFE / PAVE is (40-90) / (0-25) / (0-40) / (3-35) (mol%). The thing of (40-80) / (3-25) / (3-40) / (3-25) (mol%) is more preferable.

Moreover, it is preferable that the fluorine-containing elastomer manufactured by the manufacturing method of this invention contains 0.01-10 weight% iodine atom in an elastomer, and it is more preferable that 0.05-2 weight% is included. If the iodine atom content is less than 0.01% by weight, the crosslinking becomes insufficient, and the compression set tends to deteriorate, and if it exceeds 10% by weight, the crosslinking density is too high and the elongation is too small. As a result, the performance tends to deteriorate.

Furthermore, the number average molecular weight of the elastomer is preferably 1,000 to 300,000, and more preferably 10,000 to 200,000. If the molecular weight is less than 1,000, the viscosity tends to be too low and the handleability tends to deteriorate, and if it exceeds 300,000, the viscosity tends to increase and the handleability tends to deteriorate.

The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) is preferably 1.3 or more, and more preferably 1.5 or more. The upper limit of the molecular weight distribution is not particularly limited, but is preferably 8 or less. If the molecular weight distribution is less than 1.3, there is no problem in terms of physical properties, but the roll processability tends to deteriorate. If the molecular weight distribution exceeds 8, there is a tendency for heat generation during the roll process and adhesion to the roll to occur. .

The Mooney viscosity of the fluorine-containing elastomer produced by the production method of the present invention is not particularly limited because the optimum viscosity is selected according to the molding method. For example, in the case of injection molding, the Mooney viscosity at 100 ° C. is 10 to 120, preferably 20 to 80. If it is too high, there is a tendency to cause defects such as poor molding due to poor fluidity, and too low to easily incorporate bubbles.

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

As the oil-soluble radical polymerization initiator used in the present invention, generally known oil-soluble peroxides are used. For example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and di-sec-butylperoxydicarbonate, Peroxyesters such as t-butylperoxyisobutyrate and t-butylperoxypivalate, dialkyl peroxides such as di-t-butylperoxide, and the like, and di (ω-hydro-dodecafluorohepta) Noyl) peroxide, di (ω-hydro-tetradecafluorooctanoyl) peroxide, di (ω-hydro-hexadecafluorononanoyl) peroxide, di (perfluorobutyryl) peroxide, di (perfluorovale) Ril) peroxide, di (par Fluorohexanoyl) peroxide, di (perfluoroheptanoyl) peroxide, di (perfluorooctanoyl) peroxide, di (perfluorononanoyl) peroxide, di (ω-chloro-hexafluorobutyryl) peroxide Di (ω-chloro-decafluorohexanoyl) peroxide, di (ω-chloro-tetradecafluorooctanoyl) peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl peroxide , Ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di (dichloropentafluorobutanoyl) peroxide , Di (trichlorooctafluorohexanoyl) peroxide, di (tetrachloroundecafluorooctanoyl) peroxide, di (pentachlorotetradecafluorodecanoyl) peroxide, di (undecachlorodotriacontafluorodocosanoyl) Representative examples thereof include di [perfluoro (or fluorochloro) acyl] peroxides such as peroxide.

However, typical oil-soluble initiators such as di-isopropyl peroxycarbonate (IPP) and di-n-propyl peroxycarbonate (NPP) are explosive and expensive. In addition, since there is a problem that scales such as the wall of the polymerization tank are easily deposited during the polymerization reaction, it is preferable to use a water-soluble radical polymerization initiator.

As the water-soluble radical polymerizable initiator, generally known water-soluble peroxides are used. For example, ammonium salts such as persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, percarbonate, potassium salts, Examples thereof include sodium salt, t-butyl permaleate, t-butyl hydroperoxide and the like.

The addition amount of the water-soluble radically polymerizable initiator is not particularly limited, but the amount that does not significantly reduce the polymerization rate (for example, several ppm with respect to the water concentration) or more in the initial stage of polymerization or in sequence. Or may be added continuously. The upper limit is a range in which the polymerization reaction heat can be removed from the apparatus surface.

In the production method of the present invention, an emulsifier, a molecular weight adjusting agent, a pH adjusting agent and the like may be further added. The molecular weight modifier may be added all at once in the initial stage, or may be added continuously or dividedly.

As the emulsifier, nonionic surfactants, anionic surfactants, cationic surfactants and the like can be used. In particular, as an example of an anionic surfactant, perfluorooctanoic acid (CF ₃ (CF ₂ ) ₆ COOH 1,1,2,2-tetrahydroperfluorohexanesulfonic acid (CF ₃ (CF ₂ ) ₃ CH ₂ CH ₂ SO ₃ H), 1,1,2,2-tetrahydroperfluorooctane sulfonic acid (CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ SO ₃ H), an ammonium salt thereof, an alkali metal salt, or the like is preferable.

Examples of the molecular weight regulator include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, dimethyl succinate, isopentane, isopropanol, acetone, various mercaptans, carbon tetrachloride, cyclohexane, mono Examples thereof include iodomethane, 1-iodoethane, 1-iodo-n-propane, isopropyl iodide, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane and the like.

In addition, a buffering agent or the like may be added as appropriate, but the amount is within a range that does not impair the effects of the present invention.

Among the fluorine-containing elastomers obtained by the production method of the present invention, an ethylenically unsaturated compound containing at least one fluoroolefin, and the general formula (1):
CY ¹ ₂ = CY ² R _f ¹ X ¹ (1)
(Wherein Y ¹ and Y ² are fluorine atoms, hydrogen atoms or —CH ₃ ; R _f ¹ may have an etheric oxygen atom, and part or all of the hydrogen atoms are substituted with fluorine atoms. A linear or branched fluorine-containing alkylene group; X ¹ is an iodine atom or a bromine atom)
In a Mark-Houwink plot in which the absolute weight molecular weight and intrinsic viscosity are absolute weight molecular weight and the vertical axis is intrinsic viscosity. The fluorine-containing elastomer having a Mark-Hawin gradient a of 0.46 or less when plotted is a novel fluorine-containing elastomer.

In general, the weight average molecular weight is measured by GPC analysis using a differential refractometer (RI), which is a conversion value obtained indirectly by comparison with a standard polymer such as polystyrene, while the absolute weight molecular weight is Is obtained directly, for example, by GPC light scattering.

Intrinsic viscosity is an index relating to the size and shape of the molecule, and the measurement method will be described later.

A Mark-Houwink plot is created to see the state of long-chain branching of a polymer, and is a graph in which the horizontal axis represents the absolute weight molecular weight and the vertical axis represents the intrinsic viscosity. From this Mark-Houwin plot, the state of long chain branching of the polymer can be known, and in particular, the Mark-Houwin gradient a calculated by plotting the absolute weight molecular weight and the intrinsic viscosity is the length of the polymer of the fluorine-containing elastomer. The degree of chain branching can be specified, and it can be used as a parameter for specifying (classifying) a substance.

The Mark-Hawin gradient a of a fluorine-containing elastomer obtained by copolymerizing a conventionally known ethylenically unsaturated compound containing at least one fluoroolefin and a compound represented by the general formula (1) is 0.46. The fluorine-containing elastomer having a Mark-Hawin gradient a of 0.46 or less is a novel polymer.

Molded articles obtained by crosslinking a fluorine-containing elastomer having a crosslinking site at the molecular end with a Mark-Hawin gradient a of 0.46 or less have improved properties such as compression set resistance, heat resistance and stress relaxation behavior. The Mark-Howin gradient a is preferably 0.40 or less, more preferably 0.35 or less, and particularly preferably 0.33 or less. The lower limit is zero.

Non-limiting examples of the novel fluorine-containing elastomer of the present invention include, for example, a VdF / TFE / HFP (= 47 to 53/17 to 23/27 to 33 mol%) copolymer having a Mark-Hawin gradient a. 0.27 to 0.45, VdF / HFP (= 75 to 81/19 to 25 mol%) copolymer having a Mark-Hawin gradient a of 0.30 to 0.45, etc. can give.

The crosslinkable composition containing the fluorine-containing elastomer of the present invention comprises such a fluorine-containing elastomer and a crosslinking agent, and may contain a crosslinking aid as necessary.

What is necessary is just to select suitably as a crosslinking agent which can be used by this invention by the bridge | crosslinking system to employ | adopt. As the crosslinking system, any of a polyamine crosslinking system, a polyol crosslinking system, and a peroxide crosslinking system can be adopted, but the effect of the present invention can be remarkably exhibited particularly when crosslinking is performed with a peroxide crosslinking system.

Examples of the crosslinking agent include polyhydroxy compounds such as bisphenol AF, hydroquinone, bisphenol A, and diaminobisphenol AF in the polyol crosslinking system, and α, α'-bis (t-butylperoxy) diisopropylbenzene in the peroxide crosslinking system. Organic peroxides such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and dicumyl peroxide are polymethylene crosslinking systems such as hexamethylenediamine carbamate, N, N′-dicinnamylidene- Examples include polyamine compounds such as 1,6-hexamethylenediamine. However, it is not limited to these.

Among these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane is preferable from the viewpoint of crosslinkability and handleability.

The amount of the crosslinking agent is preferably 0.01 to 10 parts by weight and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the elastomer. If the cross-linking agent is less than 0.01 parts by weight, the degree of cross-linking is insufficient, so the performance of the fluorine-containing molded product tends to be impaired. In addition to being long, it tends to be economically undesirable.

As the crosslinking aid for the polyol crosslinking system, organic bases usually used for crosslinking elastomers such as various quaternary ammonium salts, quaternary phosphonium salts, cyclic amines, and monofunctional amine compounds can be used. Specific examples include quaternary ammonium salts such as tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltributylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium hydrogensulfate and tetrabutylammonium hydroxide; benzyltriphenylphosphonium chloride , Quaternary phosphonium salts such as tributylallylphosphonium chloride, tributyl-2-methoxypropylphosphonium chloride, benzylphenyl (dimethylamino) phosphonium chloride; monofunctional amines such as benzylmethylamine and benzylethanolamine; 1,8-diazabicyclo [ And cyclic amines such as 5.4.0] -undec-7-ene.

Peroxide crosslinking type crosslinking aids include triallyl cyanurate, triallyl isocyanurate (TAIC), tris (diallylamine-s-triazine), triallyl phosphite, N, N-diallylacrylamide, hexaallyl phosphoramide N, N, N ′, N′-tetraallyltetraphthalamide, N, N, N ′, N′-tetraallylmalonamide, trivinyl isocyanurate, 2,4,6-trivinylmethyltrisiloxane, tri (5-norbornene-2-methylene) cyanurate and the like. Among these, triallyl isocyanurate (TAIC) is preferable from the viewpoint of crosslinkability and physical properties of the cross-linked product.

The amount of the crosslinking aid is preferably 0.01 to 10 parts by weight and more preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the elastomer. If the crosslinking aid is less than 0.01 parts by weight, the crosslinking time tends to be unpractical, and if it exceeds 10 parts by weight, the crosslinking time is extremely shortened and the molded product is compressed. Permanent strain also tends to decrease.

Furthermore, usual additives such as fillers, processing aids, carbon black, inorganic fillers, metal oxides such as magnesium oxide, metal hydroxides such as calcium hydroxide, etc. do not impair the object of the present invention. As long as you use.

The preparation method and the crosslinking method 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 employed.

The tensile elongation at break (Eb) of the molded product of the present invention is preferably 180 to 550%. When the tensile elongation at break is less than 180%, the so-called “rubberiness” tends to disappear. On the other hand, if it exceeds 550%, the crosslinking density tends to decrease too much, and the compression set (CS) tends to deteriorate.

The compression set (CS) of the molded article of the present invention at 200 ° C. for 72 hours is preferably small, preferably 30% or less, and more preferably 25% or less.

Generally, when the compression set is small, the tensile elongation at break of the molded product tends to be small. Therefore, the compression set is small and the tensile strength at break of the molded product is large. Although it is very difficult, in the present invention, it is possible to combine these physical properties by limiting the addition timing of a specific CSM.

In particular, according to the fluorine-containing elastomer obtained by the production method of the present invention, a molded product having an excellent balance between tensile breaking elongation (Eb) and compression set (CS) at 72 hours, which could not be provided conventionally, is provided. You can also do that. Specifically, a molded product having Eb of 170 to 200% and CS of 10 or less, a molded product of Eb of 200 to 230% and CS of 13 or less, a molded product of Eb of 230 to 260% and CS of 14 or less, It is also possible to provide a molded product having an Eb of 260 to 290% and a CS of 18 or less, and a molded product having an Eb of 290 to 320% and a CS of 20 or less.

Here, the tensile elongation at break (Eb) and the compression set (CS) at 72 ° C. at 200 ° C. are the values obtained with the molded product obtained by crosslinking according to the standard composition and standard crosslinking conditions described below. Value.

The molded article of the present invention is a semiconductor manufacturing apparatus, a liquid crystal panel manufacturing apparatus, a plasma panel manufacturing apparatus, a plasma addressed liquid crystal panel, a field emission display panel, a solar cell substrate and other semiconductor related fields, an automobile field, an aircraft field, a rocket field, a ship. Fields, chemicals such as plants, chemicals such as pharmaceuticals, photographic fields such as developing machines, printing fields such as printing machines, coating fields such as coating equipment, food plant equipment fields, nuclear power plant equipment fields, iron plate processing equipment, etc. Can be suitably used in fields such as steel, general industrial, fuel cell, and electronic parts.

Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples.

<Weight average molecular weight (Mw) and number average molecular weight (Mn)>
Apparatus: HLC-8000 (manufactured by Tosoh Corporation)
Column: TSK gel GMH _XL- H 2 TSK gel G3000H _XL 1 TSK gel G2000H _XL 1 detector: differential refractometer developing solvent: tetrahydrofuran temperature: 35 ° C.
Sample concentration: 0.2% 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.

Measuring instrument: Automatic Mooney Viscometer Rotor rotating speed: 2rpm
Measurement temperature: 100 ° C

<Absolute weight molecular weight, intrinsic viscosity>
Apparatus: GPCmax-TDA302 system (Viscotech)
Detector: RI (differential refractometer), VISC (viscosimeter), LALLS (low angle light scattering detector), RALLS (right angle light scattering detector)
Analysis software: Viscotech Omin SEC
Column: TSKgelGMHRH 2 developing solvents: HCFC-225 / HFIP (10%)
Temperature: 30 ° C
Sample concentration: 0.4% by mass
Standard sample: PMMA

<Mark-Howin slope a>
Specifically, GPC is measured using a GPC-light scattering-viscosity system, and is calculated as the average value of the tangential slope at each point in the molecular weight range in which the peak is detected by the RI detector.

<Compression set>
The following standard blend is subjected to primary press vulcanization and secondary oven vulcanization under the following standard vulcanization conditions to produce an O-ring (P-24), and after the primary press vulcanization according to JIS-K6301. Measure compression set and compression set (CS) after secondary oven vulcanization (measurement of sample held in 25 ° C constant temperature chamber for 30 minutes after holding for 72 hours at 200 ° C under 25% pressure compression) .

(Standard formulation: 1)
Fluorine-containing elastomer 100 parts by weight Triallyl isocyanurate (TAIC) 4 parts by weight Perhexa 25B 1.5 parts by weight Carbon black MT-C 20 parts by weight

(Standard formulation: 2)
Fluorine-containing elastomer 100 parts by weight Triallyl isocyanurate (TAIC) 3 parts by weight Perhexa 25B 1.5 parts by weight Carbon black MT-C 20 parts by weight

(Standard vulcanization conditions)
Kneading method: Roll kneading press vulcanization: 10 minutes at 160 ° C Oven vulcanization: 4 hours at 180 ° C

<100% modulus (M100)>
The standard blend is subjected to primary press vulcanization and secondary oven vulcanization under the standard vulcanization conditions to obtain a sheet having a thickness of 2 mm, and the measurement is performed according to JIS-K6251.

<Tensile breaking strength (Tb) and tensile breaking elongation (Eb)>
The standard blend is subjected to primary press vulcanization and secondary oven vulcanization under the standard vulcanization conditions to obtain a sheet having a thickness of 2 mm, and the measurement is performed according to JIS-K6251.

<Hardness (Hs)>
The standard blend is subjected to primary press vulcanization and secondary oven vulcanization under the standard vulcanization conditions to obtain a sheet having a thickness of 2 mm, and the measurement is performed according to JIS-K6253.

<Vulcanization characteristics>
At the time of the primary press vulcanization, a vulcanization curve at 170 ° C. is obtained using JSR type curlastometer type II and V type, and the minimum viscosity (ML), vulcanization degree (MH), induction time (T ₁₀ ) and The optimum vulcanization time (T ₉₀ ) is determined.

<Measurement of average particle size of polymer>
The particle size is measured with Microtrac 9340UPA (HONEYWELL).

<Particle number calculation>
Using the measurement result of the average particle diameter of the polymer, the number of particles is calculated from the following formula.

<Composition analysis>
It measured using ¹⁹ F-NMR (The AC300P type made by Bruker). However, the TFE-containing polymer is measured using ¹⁹ F-NMR (FX100 model manufactured by JEOL Ltd.).

<Elemental analysis>
Measurement was performed using Yokogawa Hewlett-Packard G2350A.

Reference example 1
(Manufacture of seed polymer particles)
As a stirrer, a polymerization tank having an internal volume of 1.8 liters having an electromagnetic induction stirrer was charged with 809 g of pure water and 200 g of a 10 wt% ammonium perfluorooctanoate aqueous solution. I made it. This operation was repeated three times, 0.5 mL of isopentane was charged in a reduced pressure state, the composition in the polymerization tank at 80 ° C. was VdF / TFE / HFP = 29.0 / 13.0 / 58.0 mol%, and the polymerization tank internal pressure was 1 Each monomer was charged to 4 MPa. After completion of the temperature increase, 0.67 g of ammonium persulfate (APS) dissolved in 20 g of pure water was injected with nitrogen gas to initiate polymerization. The polymerization pressure was set to 1.4 MPa, and in order to compensate for the pressure drop during the polymerization, a VdF / TFE / HFP mixed monomer (50/20/30 (mol%)) was continuously supplied to carry out the polymerization with stirring. By the end of the polymerization, 320 g of mixed monomer was fed into the polymerization tank.

The emulsion thus obtained had an emulsion weight of 1285 g, a polymer concentration of 24.8 wt%, and an emulsion having 1.0 × 10 ¹⁵ polymer particles / water 1 g. After 360 minutes, the stirring was stopped and the unreacted monomer was released to terminate the polymerization.

Example 1
In a polymerization tank having an internal volume of 1.8 liters having the same electromagnetic induction stirrer as in Reference Example 1, 970 g of pure water and 27 g of an aqueous dispersion of polymer particles prepared in Reference Example 1 were charged, and the system was sufficiently purged with nitrogen. After that, the pressure was reduced. This operation was repeated three times. Under reduced pressure, 18 g of VdF, 22 g of TFE, and 537 g of HFP were charged, and the temperature was raised to 80 ° C. with stirring. Subsequently, 0.05 g of APS dissolved in 2.8 g of octafluoro-1,4-diiodobutane and 15 g of pure water was injected with nitrogen gas to initiate polymerization, and (a), (b), (c), (d ) And (e), the polymerization was continued, and after 3.9 hours, the stirring was stopped and the unreacted monomer was released to terminate the polymerization.

(A) Calculation of critical temperature and critical pressure according to the Peng-Robinson equation for the composition VdF / TFE / HFP = 6.5 / 5.0 / 88.5 (mol%) in the polymerization vessel was carried out by Aspen Plus Ver. As a result of using 11.1, Tc = 87.7 ° C. and Pc = 3.05 MPa. Further, when conversion is performed at a conversion temperature TR of 0.95 and a conversion pressure PR of 0.80, T = 69.7 ° C. and P = 2.44 MPa, and the polymerization conditions of Example 1 (80 ° C., 4.5 MPa) are the conversion temperature. Above and above the converted pressure.

(B) VdF / TFE / HFP (65.5 / 25.3 / 9.2 (mol%)) monomer mixture was continuously supplied, and the pressure in the gas phase portion was maintained at 3.5 MPa. Further, 282 g of the monomer mixture was supplied into the tank until the polymerization was completed.

(C) The stirring speed was maintained at 560 rpm.

(D) When 14 g of the monomer mixture described in (b) is supplied (5 wt% of the total amount of additional monomer mixture), 2.38 g of IM monomer (CF ₂ = CFOCF ₂ CF ₂ CH ₂ I) A solution prepared by dissolving 0.15 g of DS101 (CF ₃ (CF ₂ ) ₆ COONH ₄ ) in 15 g of pure water and pressurizing with nitrogen gas was added to 100 g of fluoroelastomer.

(E) Addition of IM monomer was terminated when 14 g of the monomer mixture described in (b) was added (5% by weight of the total amount of additional monomer mixture). That is, IM monomer is added only once in (d).

The weight of the obtained emulsion was 1514 g, and the polymer concentration was 29.4% by weight. Moreover, it was 445 g as a fluorine-containing elastomer, the weight average molecular weight Mw measured by GPC was 206,000, the number average molecular weight Mn was 115,000, and Mw / Mn was 1.79. The composition of the polymer measured by ¹⁹ F-NMR was VdF / TFE / HFP = 50.2 / 19.9 / 29.9 (mol%).

The mark-Houwin gradient a was calculated by plotting on the mark-Houwin plot of this fluorine-containing elastomer and found to be 0.32 (see FIG. 1).

The obtained rubbery polymer was evaluated according to the above evaluation method. The results are shown in Table 1.

Example 2
In a polymerization tank having an internal volume of 1.8 liters having the same electromagnetic induction stirrer as in Reference Example 1, 970 g of pure water and 27 g of an aqueous dispersion of polymer particles prepared in Reference Example 1 were charged, and the system was sufficiently purged with nitrogen. After that, the pressure was reduced. This operation was repeated three times. Under reduced pressure, 18 g of VdF, 22 g of TFE, and 537 g of HFP were charged, and the temperature was raised to 80 ° C. with stirring. Subsequently, 0.05 g of APS dissolved in 2.8 g of octafluoro-1,4-diiodobutane and 15 g of pure water was injected with nitrogen gas to initiate polymerization, and (a), (b), (c), (d ), (E) and (f), and the polymerization was continued. After 5.3 hours, the stirring was stopped and the unreacted monomer was released to terminate the polymerization.

(A) Calculation of critical temperature and critical pressure according to the Peng-Robinson equation for the composition VdF / TFE / HFP = 6.5 / 5.0 / 88.5 (mol%) in the polymerization vessel was carried out by Aspen Plus Ver. As a result of using 11.1, T _c = 87.7 ° C. and P _c = 3.05 MPa. Further, when conversion is performed at a conversion temperature T _R 0.95 and a conversion pressure P _R 0.80, T = 69.7 ° C. and P = 2.44 MPa, and the polymerization conditions of this example (80 ° C., 4.5 MPa) Is above the converted temperature and above the converted pressure.

(B) VdF / TFE / HFP (65.5 / 25.3 / 9.2 (mol%)) monomer mixture was continuously supplied, and the pressure in the gas phase portion was maintained at 3.5 MPa. Further, 282 g of the monomer mixture was supplied into the tank until the polymerization was completed.

(C) The stirring speed was maintained at 560 rpm.

(D) When 28 g of the monomer mixture described in (b) is supplied (10 wt% of the total amount of additional monomer mixture), 1.19 g of IM monomer (CF ₂ = CFOCF ₂ CF ₂ CH ₂ I) A solution prepared by dissolving 0.075 g of DS101 and 0.175 g of DS101 in 15 g of pure water was press-fitted with nitrogen gas.

(E) When 56 g of the monomer mixture described in (b) was supplied (20 wt% of the total amount of additional monomer mixture), 1.19 g of IM monomer and 0.075 g of DS101 were dissolved in 15 g of pure water, and nitrogen gas It was press-fitted with.

(F) The addition of the IM monomer was terminated when 56 g of the monomer mixture described in (b) (20% by weight of the total amount of additional monomer mixture) was added. That is, IM monomer was added twice (d) and (e).

The weight of the obtained emulsion was 1450 g, and the polymer concentration was 31.6% by weight. The weight of the fluorine-containing elastomer was 458 g, the weight average molecular weight Mw measured by GPC was 130,000, the number average molecular weight Mn was 94,000, and Mw / Mn was 1.46. In addition, the composition of the polymer measured by ¹⁹ F-NMR was VdF / TFE / HFP = 48.9 / 19.8 / 31.3 (mol%).

The mark-Houwin gradient a was calculated by plotting on this fluorine-containing elastomer mark-Houwin plot and found to be 0.45 (see FIG. 1).

The obtained rubbery polymer was evaluated according to the above evaluation method. The results are shown in Table 1.

Comparative Example 1
In a polymerization tank having an internal volume of 1.8 liters having the same electromagnetic induction stirrer as in Reference Example 1, 970 g of pure water and 27 g of an aqueous dispersion of polymer particles prepared in Reference Example 1 were charged, and the system was sufficiently purged with nitrogen. After that, the pressure was reduced. This operation was repeated three times. Under reduced pressure, 18 g of VdF, 22 g of TFE, and 537 g of HFP were charged, and the temperature was raised to 80 ° C. with stirring. Subsequently, 0.05 g of APS dissolved in 2.8 g of octafluoro-1,4-diiodobutane and 15 g of pure water was injected with nitrogen gas to initiate polymerization, and (a), (b), (c), (d ), (E) and (f), the polymerization was continued, and after 4.3 hours, the stirring was stopped and the unreacted monomer was released to terminate the polymerization.

(A) Calculation of critical temperature and critical pressure according to the Peng-Robinson equation for the composition VdF / TFE / HFP = 6.5 / 5.0 / 88.5 (mol%) in the polymerization vessel was carried out by Aspen Plus Ver. As a result of using 11.1, T _c = 87.7 ° C. and P _c = 3.05 MPa. Further, when conversion is performed at a conversion temperature T _R 0.95 and a conversion pressure P _R 0.80, T = 69.7 ° C. and P = 2.44 MPa, and the polymerization conditions of this example (80 ° C., 4.5 MPa) Is above the converted temperature and above the converted pressure.

(B) VdF / TFE / HFP (65.5 / 25.3 / 9.2 (mol%)) monomer mixture was continuously supplied, and the pressure in the gas phase portion was maintained at 3.5 MPa. Further, 282 g of the monomer mixture was supplied into the tank until the polymerization was completed.

(C) The stirring speed was maintained at 560 rpm.

(D) When 113 g (40% by weight of the total amount of additional monomer mixture) of the monomer mixture described in (b) was supplied, 1.19 g of IM monomer (CF ₂ = CFOCF ₂ CF ₂ CH ₂ I) A solution prepared by dissolving 0.075 g of DS101 and 0.175 g of DS101 in 15 g of pure water was press-fitted with nitrogen gas.

(E) When 141 g of the monomer mixture described in (b) was supplied (50% by weight of the total amount of additional monomer mixture), 1.19 g of IM monomer and 0.075 g of DS101 were dissolved in 15 g of pure water. It was press-fitted with.

(F) The addition of the IM monomer was terminated when 141 g of the monomer mixture described in (b) was added (50% by weight of the total amount of additional monomer mixture). That is, IM monomer is added only once in (d).

The weight of the obtained emulsion was 1523 g, and the polymer concentration was 29.9% by weight. Moreover, it was 455 g as a fluorine-containing elastomer, the weight average molecular weight Mw measured by GPC was 181,000, the number average molecular weight Mn was 112,000, and Mw / Mn was 1.62. Moreover, the composition of the polymer measured by ¹⁹ F-NMR was VdF / TFE / HFP = 49.8 / 20.1 / 30.1 (mol%).

The mark-Houwin gradient a was calculated by plotting on this fluorine-containing elastomer mark-Houwin plot, which was 0.51 (see FIG. 1).

The obtained rubbery polymer was evaluated according to the above evaluation method. The results are shown in Table 1.

Example 3
An autoclave with an internal volume of 3 liters equipped with a stirrer was charged with 0.96 liters of pure water and 2 g of C ₇ F ₁₅ COONH ₄ as an emulsifier, and the inside of the system was sufficiently replaced with nitrogen gas. Thereafter, the temperature was raised to 80 ° C. with stirring at 600 rpm, and VdF / TFE / PMVE (= 64/8/28 mol%) was injected so that the internal pressure was 1.52 MPa. Subsequently, 3 ml of an aqueous solution of ammonium persulfate (APS) 9.5 mg / ml was injected with nitrogen gas to initiate polymerization. Since the pressure decreases as the polymerization reaction proceeds, when the pressure decreases to 1.42 MPa, a monomer mixture adjusted to VdF / TFE / PMVE (= 70/12/18 mol%) is injected and added. Repressurized to .52 MPa. At this time, 0.8 g of diiodine compound I (CF ₂ ) ₄ I was injected. The monomer mixture was intermittently added, and while repeating the pressure increase and decrease, 1.5 ml of the APS was injected with nitrogen gas every 3 hours to continue the polymerization reaction. When 25 g of the monomer mixture (7% by weight of the total amount of the monomer mixture) was added, 1.62 g of IM monomer (CF ₂ = CFOCF ₂ CF ₂ CH ₂ I) (based on 100 parts by weight of the target fluorine-containing elastomer) 0.45 parts by weight) and 0.1 g of DS101 dissolved in 5 g of pure water were press-fitted with nitrogen gas. The addition of IM monomer was only this once (at 7% by weight of the total amount of monomer mixture). After that, the monomer mixture was intermittently added, and while the pressure increase and decrease were repeated, when 360 g of the monomer mixture was added, the unreacted monomer was released, the autoclave was cooled, and a dispersion with a solid content concentration of 26.4% by weight was released. Obtained. The dispersion was coagulated by adding a 4% by weight aluminum sulfate aqueous solution. The obtained coagulated product was washed with water and dried to obtain 361 g of a fluorine-containing elastomer. The composition of the fluorine-containing elastomer measured by ¹⁹ F-MNR was VdF / TFE / PMVE (= 68/12/20 mol%). Moreover, the iodine contained in the said fluorine-containing elastomer was 0.25 weight%.

When this fluorine-containing elastomer was plotted on a Mark-Houwin plot and the Mark-Houwin gradient a was calculated, it was 0.30.

The obtained rubbery polymer was evaluated according to the above evaluation method. The results are shown in Table 2.

Comparative Example 2
An autoclave with an internal volume of 3 liters equipped with a stirrer was charged with 0.96 liters of pure water and 2 g of C ₇ F ₁₅ COONH ₄ as an emulsifier, and the inside of the system was sufficiently replaced with nitrogen gas. Thereafter, the temperature was raised to 80 ° C. with stirring at 600 rpm, and VdF / TFE / PMVE (= 64/8/28 mol%) was injected so that the internal pressure was 1.52 MPa. Subsequently, 3 ml of an aqueous solution of ammonium persulfate (APS) 9.5 mg / ml was injected with nitrogen gas to initiate polymerization. Since the pressure decreases as the polymerization reaction proceeds, when the pressure decreases to 1.42 MPa, a monomer mixture adjusted to VdF / TFE / PMVE (= 70/12/18 mol%) is injected and added. Repressurized to .52 MPa. At this time, 0.8 g of diiodine compound I (CF ₂ ) ₄ I was injected. The monomer mixture was intermittently added, and while repeating the pressure increase and decrease, 1.5 ml of the APS was injected with nitrogen gas every 3 hours to continue the polymerization reaction. When 180 g of the monomer mixture is added (50 wt% of the total amount of the monomer mixture), 1.62 g of IM monomer (CF ₂ = CFOCF ₂ CF ₂ CH ₂ I) (based on 100 parts by weight of the target fluorine-containing elastomer) 0.45 parts by weight) and 0.1 g of DS101 dissolved in 5 g of pure water were press-fitted with nitrogen gas. The IM monomer was added only once (at 50% by weight of the total additional amount of monomer mixture). After that, the monomer mixture was intermittently added, and while the pressure increase and decrease were repeated, when 360 g of the monomer mixture was added, the unreacted monomer was released, the autoclave was cooled, and a dispersion with a solid content concentration of 26.4% by weight was released. Obtained. The dispersion was coagulated by adding a 4% by weight aluminum sulfate aqueous solution. The obtained coagulated product was washed with water and dried to obtain 360 g of a fluorine-containing elastomer. The composition of the fluorine-containing elastomer measured by ¹⁹ F-MNR was VdF / TFE / PMVE = 68/12/20 (mol%). Moreover, the iodine contained in the said fluorine-containing elastomer was 0.24 weight%.

When this fluorine-containing elastomer was plotted on a Mark-Houwin plot and the Mark-Houwin gradient a was calculated, it was 0.51.

The obtained rubbery polymer was evaluated according to the above evaluation method. The results are shown in Table 2.

Example 4
In a polymerization tank having an internal volume of 3 liters having the same electromagnetic induction stirrer as in Reference Example 1, 1730 g of pure water, 0.0173 g of C ₅ F ₁₁ CHO ₄ and 2,3,3,3-tetrafluoro-2- [1, 1,2,3,3,3-hexafluoro-2- (1,1,2-trifluoroallyloxy) propoxy] propionic acid ammonium salt 0.173 g was charged, and the system was sufficiently purged with nitrogen and then decompressed. did. This operation was repeated three times, and 131 g of VdF and 568 g of HFP were charged under reduced pressure, and the temperature was raised to 80 ° C. with stirring. Next, 0.0865 g of APS dissolved in 10 g of pure water was injected with nitrogen gas to start the polymerization, and the polymerization was continued under the conditions of (a), (b), (c), (d) and (e). After 2 hours, the stirring was stopped, the unreacted monomer was released, and the polymerization was stopped.

(A) Calculation of critical temperature and critical pressure by the Peng-Robinson equation for the composition VdF / HFP = 36/64 (mol%) in the polymerization tank was performed using Aspen Plus Ver. As a result of using 11.1, T _c = 87.7 ° C. and P _c = 3.05 MPa. Further, when conversion is performed at a conversion temperature TR of 0.95 and a conversion pressure of PR 0.80, T = 69.7 ° C. and P = 2.44 MPa, and the polymerization conditions (80 ° C., 6.0 MPa) in this example are equivalent to the conversion temperature. Above and above the converted pressure.
(B) A VdF / HFP (95/5 (mol%)) monomer mixture was continuously supplied, and the pressure in the gas phase portion was maintained at 6.0 MPa. Further, 470 g of the monomer mixture was supplied into the tank until the polymerization was completed.
(C) The stirring speed was maintained at 560 rpm.
(D) When 0.9 g of the monomer mixture described in (b) is supplied (2 wt% of the total amount of additional monomer mixture), 2.14 g of octafluoro-1,4-diiodobutane (100 wt. Of the desired fluorine-containing elastomer) 0.32 parts by weight) and 32.9 g (7% by weight of the total amount of additional monomer mixture) when fed, 3.53 g of IM monomer (CF ₂ = CFOCF ₂ CF ₂ CH ₂ I) was added to nitrogen. Press-fitted with gas.
(E) The addition of the IM monomer described in (d) was terminated when 32.9 g of the monomer mixture described in (b) was added (7% by weight of the total amount of additional monomer mixture). That is, IM monomer is added only once in (d).

The weight of the obtained emulsion was 2371 g, and the polymer concentration was 28.05% by weight. The fluorine-containing elastomer was 665 g, the weight average molecular weight Mw measured by GPC was 120,000, the number average molecular weight Mn was 80,000, and Mw / Mn was 1.5. Moreover, the composition of the polymer measured by ¹⁹ F-NMR was VdF / HFP = 79/21 (mol%). The Mooney viscosity at 100 ° C. was 113.

When this fluorine-containing elastomer was plotted on a Mark-Houwin plot and the Mark-Houwin gradient a was calculated, it was 0.32.

In the production method of the present invention, the start of the addition of a specific CSM is set to a time when 0 to 10% by weight of the total amount of the ethylenically unsaturated compound is added, so that compression set, heat resistance, tension A fluorine-containing elastomer that can be formed into a molded article having excellent physical properties such as elongation at break can be obtained.

Claims (1)

An ethylenically unsaturated compound comprising at least one fluoroolefin and a general formula (1):
CY ¹ ₂ = CY ² R _f ¹ X ¹ (1)
(Wherein Y ¹ and Y ² are fluorine atoms, hydrogen atoms or —CH ₃ ; R _f ¹ may have an etheric oxygen atom, and part or all of the hydrogen atoms are substituted with fluorine atoms. A linear or branched fluorine-containing alkylene group; X ¹ is an iodine atom or a bromine atom)
When the absolute weight molecular weight and the intrinsic viscosity are plotted in a Mark-Houwin plot in which the horizontal axis is the absolute weight molecular weight and the vertical axis is the intrinsic viscosity, the fluorine-containing elastomer obtained by copolymerization with the compound represented by A fluorine-containing elastomer having a Mark-Howin gradient a of 0.46 or less.

Images