Polymer blend, crosslinkable composition and article

Abstract

The present invention provides a polymer blend containing a fluorine-containing elastomer (a) and a crystalline fluorine-containing polymer (b), the fluorine-containing elastomer (a) containing tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking sites, and the crystalline fluorine-containing polymer (b) containing tetrafluoroethylene units and nitrogen-containing crosslinking sites, the fluorine-containing elastomer (a) containing tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking sites, and the crystalline fluorine-containing polymer (b) containing tetrafluoroethylene units and nitrogen-containing crosslinking sites. The melting point of the polymer blend is 310 DEG C to 320 DEG C, and the content of the crystalline fluorine-containing polymer (b) in the polymer blend is 4.0 mass% to 15.0 mass% relative to the total mass of the fluorine-containing elastomer (a) and the crystalline fluorine-containing polymer (b).

Description

Technical Field

[0001] The present invention relates to polymer blends, crosslinkable compositions and articles. Background Art

[0002] Patent Document 1 describes an emulsion mixture comprising: 1) a microemulsion comprising a composition comprising a cross-linked fluoroelastomer terpolymer consisting essentially of tetrafluoroethylene (TFE), perfluoroalkyl vinyl ether (PAVE), and perfluorocyano vinyl ether (CNVE) monomer units; and 2) a microemulsion comprising a functionalized polytetrafluoroethylene (PTFE) polymer containing 0.1 mol % to 3 mol % of perfluorocyano vinyl ether (CNVE), wherein the particle size of the functionalized PTFE polymer is approximately 10 nm to 100 nm.

[0003] Furthermore, Patent Document 1 describes a cross-linked composite material comprising: 1) a composition comprising a cross-linked fluoroelastomer terpolymer consisting essentially of tetrafluoroethylene (TFE), perfluoromethyl vinyl ether (PMVE), and perfluorocyano vinyl ether (CNVE); and 2) a composition comprising a functionalized polytetrafluoroethylene (PTFE) polymer having a particle size of 10 nm to 100 nm and comprising a cross-linkable portion, wherein the cross-linked fluoroelastomer terpolymer has a metal content of less than about 3000 ppb, and when the PTFE and the fluoroelastomer terpolymer are cross-linked to form a cross-linked composite material, the cross-linked composite material has a compression set of less than 50% when tested at 150°C.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2009-500459 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] An object of the present invention is to provide a polymer blend comprising a fluorinated elastomer and a crystalline fluorinated polymer, which has an appropriate hardness and a low compression set at high temperatures, and which can produce an article whose compression set is unlikely to increase even after use under severe conditions.

[0009] Means for solving problems

[0010] According to the present invention, there is provided a polymer blend comprising a fluorinated elastomer (a) and a crystalline fluorinated polymer (b), wherein the fluorinated elastomer (a) comprises tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking sites, and the crystalline fluorinated polymer (b) comprises tetrafluoroethylene units and nitrogen-containing crosslinking sites, the polymer blend has a melting point of 310° C. to 320° C., and the content of the crystalline fluorinated polymer (b) in the polymer blend is 4.0% by mass to 15.0% by mass relative to the total mass of the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

[0011] Effects of the Invention

[0012] According to the present invention, a polymer blend comprising a fluorinated elastomer and a crystalline fluorinated polymer can be provided, which has appropriate hardness and low compression set at high temperatures, and further can produce an article whose compression set is unlikely to increase even after use under severe conditions. DETAILED DESCRIPTION

[0013] Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0014] The polymer blend of the present invention comprises a fluorinated elastomer (a) and a crystalline fluorinated polymer (b).

[0015] Patent Document 1 describes a composite material having a compression set of less than 50% when tested at 150°C, obtained by using the aforementioned crosslinkable composite material. However, it has been found that such conventional composite materials, even when their compression set is low before use, tend to increase in compression set when used under severe conditions.

[0016] In contrast, the polymer blend of the present invention has the above-mentioned structure. Therefore, by using the polymer blend of the present invention, it is possible to obtain not only articles having appropriate hardness and low compression set at high temperatures, but also articles whose compression set is unlikely to increase even after use under severe conditions. Although the reason for this is unclear, it is presumed that this is because not only do both the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the polymer blend have nitrogen-containing crosslinking sites, but also that the melting point of the polymer blend and the content of the crystalline fluoropolymer (b) are appropriately adjusted so that the nitrogen-containing crosslinking sites of the fluoroelastomer (a) and the nitrogen-containing crosslinking sites of the crystalline fluoropolymer (b) are co-crosslinked in the polymer blend, thereby forming a co-crosslinked structure in the article at an appropriate ratio.

[0017] (Fluoroelastomer (a))

[0018] The polymer blend of the present invention contains a fluoroelastomer (a).

[0019] In the present invention, the fluoroelastomer is an amorphous fluoropolymer. "Amorphous" means that the melting peak (ΔH) observed in differential scanning calorimetry [DSC] (heating rate 10°C / min) or differential thermal analysis [DTA] (heating rate 10°C / min) of the fluoropolymer is 4.5 J / g or less. Fluoroelastomers exhibit elastomeric properties through crosslinking. Elastomeric properties refer to the ability of a polymer to stretch and maintain its original length when no force is applied to stretch the polymer.

[0020] The fluorinated elastomer may be a partially fluorinated elastomer or a perfluoroelastomer, but a perfluoroelastomer is preferred because it can provide an article having a lower compression set at high temperatures and an article in which the increase in compression set after use under severe conditions is further suppressed.

[0021] In the present invention, the partially fluorinated elastomer refers to a fluorinated polymer comprising fluorinated monomer units and perfluorinated monomer units in an amount of less than 90 mol % relative to the total monomer units, and has a glass transition temperature of 20° C. or lower and a melting peak (ΔH) of 4.5 J / g or lower.

[0022] In the present invention, a perfluoroelastomer refers to a fluoropolymer having a perfluoroelastomer content of 90 mol% or more, preferably 91 mol% or more, relative to all monomer units. This fluoroelastomer has a glass transition temperature of 20°C or less and a melting peak (ΔH) of 4.5 J / g or less. Furthermore, the fluorine atom concentration in the fluoroelastomer is 71% by mass or more, preferably 71.5% by mass or more. In the present invention, the fluorine atom concentration in the fluoroelastomer is calculated based on the type and content of each monomer constituting the fluoroelastomer to determine the fluorine atom concentration (mass %) in the fluoroelastomer.

[0023] In the present invention, a perfluoromonomer refers to a monomer whose molecule does not contain carbon-hydrogen bonds. Such perfluoromonomers may also include monomers in which, in addition to carbon and fluorine atoms, some of the fluorine atoms bonded to carbon atoms are replaced by chlorine atoms. Furthermore, such monomers may include nitrogen, oxygen, sulfur, phosphorus, boron, or silicon atoms in addition to carbon atoms. Preferred perfluoromonomers include those in which all hydrogen atoms are replaced by fluorine atoms. Such perfluoromonomers do not include monomers that provide crosslinking sites.

[0024] The monomer providing a crosslinking site is a monomer having a crosslinking group (curing site monomer) which provides a crosslinking site for forming a crosslink in the fluorinated polymer.

[0025] In the present invention, the contents of the fluorinated elastomer (a), the crystalline fluorinated polymer (b) and each monomer constituting the polymer blend can be calculated by appropriately combining NMR, FT-IR, elemental analysis, fluorescent X-ray analysis and other known methods depending on the types of monomers.

[0026] From the viewpoint of imparting appropriate hardness to an article, obtaining an article having a smaller compression set at high temperatures, and further obtaining an article in which an increase in compression set after use under severe conditions is further suppressed, the Mooney viscosity ML (1+20) of the fluoroelastomer (a) at 170°C is preferably 30 or more, more preferably 50 or more, even more preferably 60 or more, and even more preferably 70 or more, and is preferably 150 or less, more preferably 130 or less, and even more preferably 120 or less.

[0027] The Mooney viscosity of the fluorinated elastomer (a) can be adjusted to fall within the above range by adjusting the composition, molecular weight, etc. of the monomers constituting the fluorinated elastomer (a).

[0028] The Mooney viscosity can be measured at 170° C. using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES, Inc. in accordance with JIS K6300.

[0029] From the viewpoint of imparting appropriate hardness to an article, obtaining an article having a smaller compression set at high temperatures, and further obtaining an article in which an increase in compression set after use under severe conditions is further suppressed, the glass transition temperature of the fluoroelastomer (a) is preferably -30°C or higher, more preferably -20°C or higher, even more preferably -10°C or higher, and preferably 10°C or lower, more preferably 5°C or lower, and even more preferably 0°C or lower.

[0030] The glass transition temperature can be calculated as follows: using a differential scanning calorimeter (manufactured by Hitachi High-Technologies Corporation, X-DSC7000), 3 mg of a sample is heated at 20°C / min to obtain a DSC curve, and the glass transition temperature is calculated as the temperature of the midpoint of the two intersections of the extended line of the baseline before and after the secondary transition of the DSC curve and the tangent line at the inflection point of the DSC curve.

[0031] The fluorine-containing elastomer (a) contained in the polymer blend of the present invention contains tetrafluoroethylene (TFE) units, fluoroalkyl vinyl ether (FAVE) units and nitrogen-containing crosslinking sites.

[0032] From the viewpoint of obtaining an article having a smaller compression set at high temperature and an article having an increase in compression set after use under severe conditions being further suppressed, the FAVE forming the FAVE unit is preferably selected from

[0033] General formula (11): CF2=CF-ORf 13

[0034] (Where Rf 13 represents a perfluoroalkyl group having 1 to 8 carbon atoms. ) represents a fluorine-containing monomer,

[0035] General formula (12): CF2=CFOCF2ORf 14

[0036] (Where Rf 14 a fluorinated monomer represented by a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms containing 1 to 3 oxygen atoms, and

[0037] General formula (13): CF2=CFO(CF2CF(Y 15 )O) m (CF2) n F

[0038] (Where Y 15 represents a fluorine atom or a trifluoromethyl group. m is an integer of 1 to 4. n is an integer of 1 to 4. At least one member selected from the group consisting of the fluorinated monomers represented by

[0039] As FAVE, preferably, the fluorine-containing monomer represented by the general formula (11) is used, more preferably, at least one selected from the group consisting of CF2=CF-OCF3 (perfluoro(methyl vinyl ether) (PMVE)), CF2=CF-OCF2CF3 and CF2=CF-OCF2CF2CF3, and further preferably, CF2=CF-OCF3.

[0040] The fluorinated elastomer (a) contained in the polymer blend of the present invention contains nitrogen-containing crosslinking sites. The nitrogen-containing crosslinking sites are sites containing at least one nitrogen atom and are sites for forming crosslinks in the fluorinated elastomer (a).

[0041] As the nitrogen-containing crosslinking site, a nitrogen-containing crosslinking group is preferred. The nitrogen-containing crosslinking group is not particularly limited as long as it contains at least one nitrogen atom and provides a crosslinking site for forming a crosslink on the fluoropolymer. Examples thereof include a cyano group, an azide group, a sulfonyl azide group, a carbonyl azide group, and an amidine group. As the nitrogen-containing crosslinking group, a cyano group is preferred because it can produce an article with a lower compression set at high temperatures and an article with a further suppressed increase in compression set after use under harsh conditions.

[0042] When the fluorinated elastomer (a) has cyano groups as nitrogen-containing crosslinking sites, the cyano groups can be crosslinked by cyclotrimerization to form triazine rings, or by using a tetraamine compound as a crosslinking agent to form imidazole rings. Such crosslinking can impart moderate hardness and excellent compression set properties to the article.

[0043] Nitrogen-containing crosslinking sites can be introduced into the fluoroelastomer, for example, by copolymerizing monomers having nitrogen-containing crosslinking groups during the production of the fluoroelastomer. Furthermore, nitrogen-containing crosslinking sites can be introduced into the fluoroelastomer, for example, by polymerizing monomers in the presence of a nitrogen-containing chain transfer agent during the production of the fluoroelastomer. Examples of nitrogen-containing chain transfer agents include I(CF2) n A compound represented by CN (n is an integer of 1 to 15). Furthermore, the nitrogen-containing crosslinking site can be introduced into the fluoroelastomer by, for example, reacting a functional group (e.g., -COF, -COOH, etc.) generated at the terminal of the fluoroelastomer with ammonia after the fluoroelastomer is produced.

[0044] In one embodiment of the fluorinated elastomer (a), a monomer unit having a nitrogen-containing crosslinkable group is contained.

[0045] As the monomer having a nitrogen-containing crosslinking group, a monomer having a cyano group is preferred. Examples of the monomer having a cyano group (-CN group) include:

[0046] Formula: CY 1 2=CY 1 (CF2) n -CN

[0047] (Where Y 1 are each independently a hydrogen atom or a fluorine atom, and n is an integer from 1 to 8)

[0048] Formula: CF2=CFCF2Rf 8 -CN

[0049] (Where Rf 8 -(OCF2) n -or-(OCF(CF3)) n-, n is an integer from 0 to 5) formula: CF2=CFCF2(OCF(CF3)CF2) m (OCH2CF2CF2) n OCH2CF2-CN (wherein m is an integer from 0 to 5, and n is an integer from 0 to 5)

[0050] Formula: CF2=CFCF2(OCH2CF2CF2) m (OCF(CF3)CF2) n OCF(CF3)-CN (wherein, m is an integer from 0 to 5, and n is an integer from 0 to 5)

[0051] Formula: CF2=CF(OCF2CF(CF3)) m O(CF2) n -CN

[0052] (wherein m is an integer from 0 to 5, and n is an integer from 1 to 8)

[0053] Formula: CF2=CF(OCF2CF(CF3)) m -CN

[0054] (wherein m is an integer from 1 to 5)

[0055] Formula: CF2=CFOCF2(CF(CF3)OCF2) n CF(-CN)CF3

[0056] (where n is an integer from 1 to 4)

[0057] Formula: CF2=CFO(CF2) n OCF(CF3)-CN

[0058] (where n is an integer from 2 to 5)

[0059] Formula: CF2=CFO(CF2) n -(C6H4)-CN

[0060] (where n is an integer from 1 to 6)

[0061] Formula: CF2=CF(OCF2CF(CF3)) n OCF2CF(CF3)-CN

[0062] (where n is an integer from 1 to 2)

[0063] Formula: CH2=CFCF2O(CF(CF3)CF2O) n CF(CF3)-CN

[0064] (where n is an integer from 0 to 5)

[0065] Formula: CF2=CFO(CF2CF(CF3)O) m (CF2) n -CN

[0066] (wherein m is an integer from 0 to 5, and n is an integer from 1 to 3)

[0067] Formula: CH2=CFCF2OCF(CF3)OCF(CF3)-CN

[0068] Formula: CH2=CFCF2OCH2CF2-CN

[0069] Formula: CF2=CFO(CF2CF(CF3)O) m CF2CF(CF3)-CN

[0070] (wherein m is an integer greater than 0)

[0071] Formula: CF2=CFOCF(CF3)CF2O(CF2) n -CN

[0072] (where n is an integer greater than or equal to 1)

[0073] Formula: CF2=CFOCF2OCF2CF(CF3)OCF2-CN

[0074] Formula: CF2=CFO(CF2)3CN

[0075] Formula: CF2=CFO(CF2)5CN

[0076] The monomers shown in the foregoing may be used alone or in any combination.

[0077] Among the above, preferably

[0078] Formula: CF2=CF(OCF2CF(CF3)) m O(CF2) n -CN

[0079] (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8), more preferably a monomer represented by CF2=CFOCF2CF(CF3)OCF2CF2CN.

[0080] The content of nitrogen-containing crosslinking sites in the fluorinated elastomer (a) is preferably from 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a).

[0081] The content of nitrogen-containing crosslinking sites can be measured by infrared spectroscopy (IR).

[0082] The content of nitrogen-containing crosslinkable groups in the fluorinated elastomer (a) is preferably from 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a).

[0083] The content of the nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0084] The cyano group content in the fluorinated elastomer (a) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a).

[0085] The cyano group content can be determined by infrared spectroscopy (IR).

[0086] The content of monomer units having nitrogen-containing crosslinkable groups in the fluorinated elastomer (a) is preferably from 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a).

[0087] The content of the monomer unit having a nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0088] The content of the monomer units having a cyano group in the fluorinated elastomer (a) is preferably from 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a).

[0089] The content of the monomer unit having a cyano group can be measured by infrared spectroscopy (IR).

[0090] As the fluorinated elastomer (a), a copolymer containing TFE units, FAVE units and monomer units having a nitrogen-containing crosslinking group is preferred, a copolymer containing TFE units, FAVE units and monomer units having a cyano group is more preferred, and a copolymer containing TFE units, PMVE units and monomer units having a cyano group is further preferred.

[0091] The content of TFE units and FAVE units in the fluoroelastomer (a) is preferably 97.0 to 99.5 mol%, more preferably 98.0 mol% or more, further preferably 98.5 mol% or more, based on 100 mol% of all monomer units constituting the fluoroelastomer (a).

[0092] In the copolymer containing TFE units, FAVE units and monomer units having nitrogen-containing crosslinkable groups, the content ratio (mol %) of TFE units / FAVE units / monomer units having nitrogen-containing crosslinkable groups is preferably 44.0 to 89.9 / 9.6 to 54.9 / 0.5 to 3.0, more preferably 50.0 to 78.0 / 20.0 to 49.5 / 0.5 to 2.0, and further preferably 55.0 to 69.5 / 30.0 to 44.5 / 0.5 to 1.5.

[0093] (Crystalline fluorinated polymer (b))

[0094] The polymer blend of the present invention contains a crystalline fluorinated polymer (b).

[0095] In the present invention, a crystalline fluoropolymer is a partially crystalline fluoropolymer and a fluoroplastic. Crystalline fluoropolymers have a melting point and exhibit thermoplastic properties. They can be melt-processable or non-melt-processable. In the present invention, melt-processability means that the polymer can be melt-processed using conventional processing equipment such as extruders and injection molding machines.

[0096] The melting point of the crystalline fluorinated polymer (b) is 310 to 320° C. The melting point is preferably 311° C. or higher, more preferably 312° C. or higher, further preferably 313° C. or higher, and is preferably 319° C. or lower, more preferably 318° C. or lower.

[0097] If the melting point of the crystalline fluoropolymer (b) is too low, it may be difficult to obtain an article having a small compression set at high temperatures. If the melting point of the crystalline fluoropolymer (b) is too high, it may be difficult to obtain an article having a low compression set even after use under severe conditions.

[0098] The melting point of the crystalline fluoropolymer (b) can be adjusted to the above range by, for example, adjusting the composition of the monomers constituting the crystalline fluoropolymer (b). Increasing the content of tetrafluoroethylene units tends to increase the melting point of the crystalline fluoropolymer (b), while decreasing the content of tetrafluoroethylene units tends to decrease the melting point of the crystalline fluoropolymer (b).

[0099] The melting point of the crystalline fluoropolymer (b) can be measured by weighing approximately 10 mg of the crystalline fluoropolymer (b) that has not been heated to a temperature of 300°C or higher, placing it in a dedicated aluminum pan, and measuring it using a TG / DTA (differential thermal and gravimetric simultaneous analysis). The aluminum pan is heated at a rate of 10°C / minute from 25°C to 600°C in an air atmosphere to obtain a DTA curve. The temperature corresponding to the peak in the resulting DTA curve is determined as the melting point of the polymer blend.

[0100] When the only substance showing a melting point in the polymer blend is the crystalline fluorinated polymer (b), the melting point of the crystalline fluorinated polymer (b) can be considered to be the same as that of the polymer blend. Therefore, by measuring the melting point of the polymer blend, the melting point of the crystalline fluorinated polymer (b) can also be determined.

[0101] The crystalline fluorinated polymer (b) contained in the polymer blend of the present invention contains tetrafluoroethylene (TFE) units and nitrogen-containing crosslinking sites.

[0102] The crystalline fluorinated polymer (b) may contain other monomer units formed from other monomers copolymerizable with TFE (excluding TFE units and monomer units having a nitrogen-containing crosslinking group).

[0103] As other monomers (excluding TFE and monomers having a nitrogen-containing crosslinking group), there are no particular limitations as long as they can be copolymerized with TFE, and examples thereof include perfluoroolefins such as hexafluoropropylene [HFP]; chlorofluoroolefins such as chlorotrifluoroethylene [CTFE]; hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride [VDF]; perfluorovinyl ether; and perfluoroalkylethylenes such as ethylene.

[0104] The content of other monomer units in the crystalline fluorinated polymer (b) is preferably 0 mol% to 0.10 mol%, more preferably 0.06 mol% or less, further preferably 0.02 mol% or less, and may be 0 mol%, relative to all monomer units constituting the crystalline fluorinated polymer (b).

[0105] The crystalline fluorinated polymer (b) contained in the polymer blend of the present invention contains a nitrogen-containing crosslinking site. The nitrogen-containing crosslinking site is a site containing at least one nitrogen atom and is a site where the crystalline fluorinated polymer (b) forms a crosslink.

[0106] As the nitrogen-containing crosslinking site, a nitrogen-containing crosslinking group is preferred. The nitrogen-containing crosslinking group is not particularly limited as long as it contains at least one nitrogen atom and provides a crosslinking site for forming a crosslink on the fluoropolymer. Examples thereof include a cyano group, an azide group, a sulfonyl azide group, a carbonyl azide group, and an amidine group. As the nitrogen-containing crosslinking group, a cyano group is preferred because it can produce an article with a lower compression set at high temperatures and an article with a further suppressed increase in compression set after use under harsh conditions.

[0107] When the crystalline fluorinated polymer (b) has cyano groups as nitrogen-containing crosslinking sites, the cyano groups can be crosslinked by cyclotrimerization to form triazine rings, or by using a tetraamine compound as a crosslinking agent to form imidazole rings. Such crosslinking can impart moderate hardness and excellent compression set properties to the article.

[0108] The nitrogen-containing crosslinking site can be introduced into the crystalline fluoropolymer by, for example, copolymerizing a monomer having a nitrogen-containing crosslinking group during the production of the crystalline fluoropolymer. Alternatively, the nitrogen-containing crosslinking site can be introduced into the crystalline fluoropolymer by, for example, polymerizing the monomer in the presence of a nitrogen-containing chain transfer agent during the production of the crystalline fluoropolymer. Examples of the nitrogen-containing chain transfer agent include I(CF2) n A compound represented by CN (n is an integer of 1 to 15). Furthermore, for example, after producing a crystalline fluoropolymer, nitrogen-containing crosslinking sites can be introduced into the crystalline fluoropolymer by reacting a functional group (e.g., -COF, -COOH, etc.) generated at the terminal of the crystalline fluoropolymer with ammonia.

[0109] In one embodiment of the crystalline fluorinated polymer (b), a monomer unit having a nitrogen-containing crosslinkable group is contained.

[0110] As the monomer having a nitrogen-containing crosslinking group, a monomer having a cyano group is preferred. Examples of the monomer having a cyano group (-CN group) include:

[0111] Formula: CY 1 2=CY 1 (CF2) n -CN

[0112] (Where Y 1 are each independently a hydrogen atom or a fluorine atom, and n is an integer from 1 to 8)

[0113] Formula: CF2=CFCF2Rf 8 -CN

[0114] (Where Rf 8 -(OCF2) n -or-(OCF(CF3)) n -, n is an integer from 0 to 5)

[0115] Formula: CF2=CFCF2(OCF(CF3)CF2) m (OCH2CF2CF2) n OCH2CF2-CN

[0116] (wherein m is an integer from 0 to 5, and n is an integer from 0 to 5)

[0117] Formula: CF2=CFCF2(OCH2CF2CF2) m (OCF(CF3)CF2) n OCF(CF3)-CN

[0118] (wherein m is an integer from 0 to 5, and n is an integer from 0 to 5)

[0119] Formula: CF2=CF(OCF2CF(CF3)) m O(CF2) n -CN

[0120] (wherein m is an integer from 0 to 5, and n is an integer from 1 to 8)

[0121] Formula: CF2=CF(OCF2CF(CF3)) m -CN

[0122] (wherein m is an integer from 1 to 5)

[0123] Formula: CF2=CFOCF2(CF(CF3)OCF2) n CF(-CN)CF3

[0124] (where n is an integer from 1 to 4)

[0125] Formula: CF2=CFO(CF2) n OCF(CF3)-CN

[0126] (where n is an integer from 2 to 5)

[0127] Formula: CF2=CFO(CF2) n -(C6H4)-CN

[0128] (where n is an integer from 1 to 6)

[0129] Formula: CF2=CF(OCF2CF(CF3)) n OCF2CF(CF3)-CN

[0130] (where n is an integer from 1 to 2)

[0131] Formula: CH2=CFCF2O(CF(CF3)CF2O) n CF(CF3)-CN

[0132] (where n is an integer from 0 to 5)

[0133] Formula: CF2=CFO(CF2CF(CF3)O) m (CF2) n -CN

[0134] (wherein m is an integer from 0 to 5, and n is an integer from 1 to 3)

[0135] Formula: CH2=CFCF2OCF(CF3)OCF(CF3)-CN

[0136] Formula: CH2=CFCF2OCH2CF2-CN

[0137] Formula: CF2=CFO(CF2CF(CF3)O) m CF2CF(CF3)-CN

[0138] (wherein m is an integer greater than 0)

[0139] Formula: CF2=CFOCF(CF3)CF2O(CF2) n -CN

[0140] (where n is an integer greater than or equal to 1)

[0141] Formula: CF2=CFOCF2OCF2CF(CF3)OCF2-CN

[0142] Formula: CF2=CFO(CF2)3CN

[0143] Formula: CF2=CFO(CF2)5CN

[0144] The monomers shown in the foregoing may be used alone or in any combination.

[0145] Among the above, preferably

[0146] Formula: CF2=CF(OCF2CF(CF3)) m O(CF2) n -CN

[0147] (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8), more preferably a monomer represented by CF2=CFOCF2CF(CF3)OCF2CF2CN.

[0148] The content of nitrogen-containing crosslinking sites in the crystalline fluorinated polymer (b) is preferably from 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the crystalline fluorinated polymer (b).

[0149] The content of nitrogen-containing crosslinking sites can be measured by infrared spectroscopy (IR).

[0150] The content of nitrogen-containing crosslinkable groups in the crystalline fluorinated polymer (b) is preferably from 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the crystalline fluorinated polymer (b).

[0151] The content of the nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0152] The cyano group content in the crystalline fluorinated polymer (b) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the crystalline fluorinated polymer (b).

[0153] The cyano group content can be determined by infrared spectroscopy (IR).

[0154] The content of the monomer units having a nitrogen-containing crosslinkable group in the crystalline fluorinated polymer (b) is preferably from 0.5 mol% to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the crystalline fluorinated polymer (b).

[0155] The content of the monomer unit having a nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0156] The content of the monomer units having a cyano group in the crystalline fluorinated polymer (b) is preferably from 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the crystalline fluorinated polymer (b).

[0157] The content of the monomer unit having a cyano group can be measured by infrared spectroscopy (IR).

[0158] The crystalline fluorinated polymer (b) is preferably a copolymer comprising a TFE unit and a monomer unit having a nitrogen-containing crosslinkable group, and more preferably a copolymer comprising a TFE unit and a monomer unit having a cyano group.

[0159] The content of TFE units in the crystalline fluoropolymer (b) is preferably 97.0 to 99.5 mol%, more preferably 98.0 mol% or more, further preferably 98.5 mol% or more, based on 100 mol% of all monomer units constituting the crystalline fluoropolymer (b).

[0160] (Polymer blend)

[0161] The polymer blend of the present invention has a melting point of 310° C. to 320° C. The melting point of the polymer blend is preferably 311° C. or higher, more preferably 312° C. or higher, and even more preferably 313° C. or higher, and preferably 319° C. or lower, and more preferably 318° C. or lower.

[0162] If the melting point of the polymer blend is too low, it may be difficult to obtain an article with a small compression set at high temperatures. If the melting point of the polymer blend is too high, it may be difficult to obtain an article whose compression set does not increase significantly even after use under harsh conditions. If a polymer blend that does not exhibit a clear melting point is used, it may be difficult to obtain an article with appropriate hardness.

[0163] The melting point of the polymer blend can be adjusted to the above range by adjusting the melting point of the crystalline fluorinated polymer (b) and the content of the crystalline fluorinated polymer (b), for example.

[0164] The melting point of a polymer blend can be measured using a TG / DTA (differential thermal gravimetric analysis) apparatus by weighing approximately 10 mg of the polymer blend, which has not been heated to a temperature of 300°C or higher, and placing it in a dedicated aluminum pan. The temperature of the aluminum pan is raised at a rate of 10°C / minute from 25°C to 600°C in an atmospheric atmosphere to produce a DTA curve. The temperature corresponding to the peak in the resulting DTA curve is determined as the melting point of the polymer blend.

[0165] From the perspectives of imparting appropriate hardness to an article, obtaining an article with lower compression set at high temperatures, and further obtaining an article in which the increase in compression set after use under severe conditions is further suppressed, the Mooney viscosity ML (1+20) of the polymer blend at 170°C is preferably 30 to 150, more preferably 50 or more, even more preferably 60 or more, even more preferably 70 or more, more preferably 130 or less, and even more preferably 120 or less.

[0166] The Mooney viscosity of the polymer blend can be adjusted to the above range by adjusting the Mooney viscosity of the fluorinated elastomer (a) and the content of the fluorinated elastomer (a), for example.

[0167] The Mooney viscosity can be measured at 170° C. using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES, Inc. in accordance with JIS K6300.

[0168] From the perspectives of imparting appropriate hardness to an article, obtaining an article with lower compression set at high temperatures, and further obtaining an article in which the increase in compression set after use under severe conditions is further suppressed, the glass transition temperature of the polymer blend is preferably -30°C or higher, more preferably -20°C or higher, and even more preferably -10°C or higher, and is preferably 10°C or lower, more preferably 5°C or lower, and even more preferably 0°C or lower.

[0169] The glass transition temperature can be calculated as follows: using a differential scanning calorimeter (manufactured by Hitachi High-Technologies Corporation, X-DSC7000), 3 mg of a sample is heated at 20°C / min to obtain a DSC curve, and the glass transition temperature is calculated as the temperature of the midpoint of the two intersections of the extended line of the baseline before and after the secondary transition of the DSC curve and the tangent line at the inflection point of the DSC curve.

[0170] The polymer blend of the present invention comprises a fluorinated elastomer (a) and a crystalline fluorinated polymer (b). The content of the crystalline fluorinated polymer (b) in the polymer blend is 4.0% to 15.0% by mass relative to the total mass of the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

[0171] The content of the crystalline fluorinated polymer (b) in the polymer blend is preferably 4.2 mass% or more, more preferably 4.4 mass% or more, further preferably 4.6 mass% or more, and is preferably 14.0 mass% or less, more preferably 13.0 mass% or less, further preferably 12.0 mass% or less.

[0172] If the content of the crystalline fluoropolymer (b) in the polymer blend is too low, it is difficult to impart appropriate hardness to the article. If the content of the crystalline fluoropolymer (b) in the polymer blend is too high, the hardness of the article becomes too high, or it is difficult to obtain an article with a small compression set at high temperatures, or to obtain an article with a low compression set even after use under severe conditions.

[0173] The content of the crystalline fluoropolymer (b) in the polymer blend can be measured by weighing about 10 mg of the polymer blend that has not been heated to a temperature above 300°C and placing it in a dedicated aluminum pan and using TG / DTA (differential thermal and gravimetric simultaneous measurement apparatus). The aluminum pan is heated at a temperature range of 25°C to 600°C at a rate of 10°C / minute under an atmospheric atmosphere to obtain a TG curve, and the weight loss rate is calculated from the obtained TG curve to determine the content. Generally, the fluoroelastomer (a) in the polymer blend thermally decomposes at a lower temperature than the crystalline fluoropolymer (b). Therefore, the weight loss rate of each of the fluoroelastomer (a) and the crystalline fluoropolymer (b) caused by thermal decomposition can be separately understood from the TG curve.

[0174] The content of the crystalline fluorinated polymer (b) in the polymer blend can also be determined by calculation from the amounts of raw materials used, if the production conditions of the polymer blend are known.

[0175] The polymer blend of the present invention comprises a fluoroelastomer (a) and a crystalline fluoropolymer (b). The fluoroelastomer (a) comprises tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking sites, and the crystalline fluoropolymer (b) comprises tetrafluoroethylene units and nitrogen-containing crosslinking sites.

[0176] From the viewpoint of obtaining an article having a smaller compression set at high temperature and an article having an increase in compression set after use under severe conditions being further suppressed, the FAVE forming the FAVE unit is preferably selected from

[0177] General formula (11): CF2=CF-ORf 13

[0178] (Where Rf 13 represents a perfluoroalkyl group having 1 to 8 carbon atoms. ) represents a fluorine-containing monomer,

[0179] General formula (12): CF2=CFOCF2ORf 14

[0180] (Where Rf 14 a fluorinated monomer represented by a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms containing 1 to 3 oxygen atoms, and

[0181] General formula (13): CF2=CFO(CF2CF(Y 15 )O) m (CF2) n F

[0182] (Where Y 15 represents a fluorine atom or a trifluoromethyl group. m is an integer of 1 to 4. n is an integer of 1 to 4. At least one member selected from the group consisting of the fluorinated monomers represented by

[0183] As FAVE, preferably, the fluorine-containing monomer represented by the general formula (11) is used, more preferably, at least one selected from the group consisting of CF2=CF-OCF3 (perfluoro(methyl vinyl ether) (PMVE)), CF2=CF-OCF2CF3 and CF2=CF-OCF2CF2CF3, and further preferably, CF2=CF-OCF3.

[0184] The content ratio of tetrafluoroethylene units to fluoroalkyl vinyl ether units in the polymer blend, as measured by a molar ratio (tetrafluoroethylene units / fluoroalkyl vinyl ether units), is preferably 50 / 50 to 70 / 30, more preferably 51 / 49 or greater, even more preferably 52 / 48 or greater, and even more preferably 53 / 47 or greater, and more preferably 69 / 31 or less, and even more preferably 68 / 32 or less. Furthermore, the content ratio of tetrafluoroethylene units to fluoroalkyl vinyl ether units in the polymer blend, as measured by a molar ratio (tetrafluoroethylene units / fluoroalkyl vinyl ether units), may be 54 / 46 or greater, 65 / 35 or less, or 60 / 40 or less.

[0185] If the molar ratio (tetrafluoroethylene units / fluoroalkyl vinyl ether units) is too high, it may be difficult to impart appropriate hardness to the article. If the molar ratio is too low, the hardness of the article may become too high, or it may be difficult to obtain an article with a small compression set at high temperatures, or it may be difficult to obtain an article with a low compression set even after use under severe conditions.

[0186] The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) contain nitrogen-containing crosslinking sites. Nitrogen-containing crosslinking sites are sites containing at least one nitrogen atom and are sites where the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) are crosslinked in the polymer blend.

[0187] As the nitrogen-containing crosslinking site, a nitrogen-containing crosslinking group is preferred. The nitrogen-containing crosslinking group is not particularly limited as long as it contains at least one nitrogen atom and provides a crosslinking site for forming a crosslink on the fluoropolymer. Examples thereof include a cyano group, an azide group, a sulfonyl azide group, a carbonyl azide group, and an amidine group. As the nitrogen-containing crosslinking group, a cyano group is preferred because it can produce an article with a lower compression set at high temperatures and an article with a further suppressed increase in compression set after use under harsh conditions.

[0188] When the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) have cyano groups as nitrogen-containing crosslinking sites, the cyano groups can be crosslinked by cyclotrimerization to form triazine rings, or by using a tetraamine compound as a crosslinking agent to form imidazole rings. Such crosslinking can impart moderate hardness and excellent compression set properties to the article.

[0189] Nitrogen-containing crosslinking sites can be introduced into the crystalline fluoropolymer by, for example, copolymerizing monomers having nitrogen-containing crosslinking groups during the production of the fluoroelastomer and the crystalline fluoropolymer. Furthermore, nitrogen-containing crosslinking sites can be introduced into the fluoroelastomer and the crystalline fluoropolymer by, for example, polymerizing monomers in the presence of a nitrogen-containing chain transfer agent during the production of the fluoroelastomer and the crystalline fluoropolymer. Examples of nitrogen-containing chain transfer agents include I(CF2) n A compound represented by CN (n is an integer of 1 to 15). Furthermore, the nitrogen-containing crosslinking site can be introduced into the fluoroelastomer or crystalline fluoropolymer by, for example, reacting a functional group (e.g., -COF, -COOH, etc.) generated at the terminal of the fluoroelastomer or crystalline fluoropolymer after the production of the fluoroelastomer or crystalline fluoropolymer with ammonia.

[0190] In one embodiment of the fluorinated elastomer (a) and the crystalline fluorinated polymer (b), a monomer unit having a nitrogen-containing crosslinkable group is contained.

[0191] As the monomer having a nitrogen-containing crosslinking group, a monomer having a cyano group is preferred. Examples of the monomer having a cyano group (-CN group) include:

[0192] Formula: CY 1 2=CY 1 (CF2) n -CN

[0193] (Where Y 1 are each independently a hydrogen atom or a fluorine atom, and n is an integer from 1 to 8)

[0194] Formula: CF2=CFCF2Rf 8 -CN

[0195] (Where Rf 8 -(OCF2) n -or-(OCF(CF3)) n -, n is an integer from 0 to 5)

[0196] Formula: CF2=CFCF2(OCF(CF3)CF2) m (OCH2CF2CF2) n OCH2CF2-CN

[0197] (wherein m is an integer from 0 to 5, and n is an integer from 0 to 5)

[0198] Formula: CF2=CFCF2(OCH2CF2CF2) m (OCF(CF3)CF2) n OCF(CF3)-CN

[0199] (wherein m is an integer from 0 to 5, and n is an integer from 0 to 5)

[0200] Formula: CF2=CF(OCF2CF(CF3)) m O(CF2) n -CN

[0201] (wherein m is an integer from 0 to 5, and n is an integer from 1 to 8)

[0202] Formula: CF2=CF(OCF2CF(CF3)) m -CN

[0203] (wherein m is an integer from 1 to 5)

[0204] Formula: CF2=CFOCF2(CF(CF3)OCF2) n CF(-CN)CF3

[0205] (where n is an integer from 1 to 4)

[0206] Formula: CF2=CFO(CF2) n OCF(CF3)-CN

[0207] (where n is an integer from 2 to 5)

[0208] Formula: CF2=CFO(CF2) n -(C6H4)-CN

[0209] (where n is an integer from 1 to 6)

[0210] Formula: CF2=CF(OCF2CF(CF3)) n OCF2CF(CF3)-CN

[0211] (where n is an integer from 1 to 2)

[0212] Formula: CH2=CFCF2O(CF(CF3)CF2O) n CF(CF3)-CN

[0213] (where n is an integer from 0 to 5)

[0214] Formula: CF2=CFO(CF2CF(CF3)O) m (CF2) n -CN

[0215] (wherein m is an integer from 0 to 5, and n is an integer from 1 to 3)

[0216] Formula: CH2=CFCF2OCF(CF3)OCF(CF3)-CN

[0217] Formula: CH2=CFCF2OCH2CF2-CN

[0218] Formula: CF2=CFO(CF2CF(CF3)O) m CF2CF(CF3)-CN

[0219] (wherein m is an integer greater than 0)

[0220] Formula: CF2=CFOCF(CF3)CF2O(CF2) n -CN

[0221] (where n is an integer greater than or equal to 1)

[0222] Formula: CF2=CFOCF2OCF2CF(CF3)OCF2-CN

[0223] Formula: CF2=CFO(CF2)3CN

[0224] Formula: CF2=CFO(CF2)5CN

[0225] The monomers shown in the foregoing may be used alone or in any combination.

[0226] Among the above, preferably

[0227] Formula: CF2=CF(OCF2CF(CF3)) m O(CF2) n -CN

[0228] (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8), more preferably a monomer represented by CF2=CFOCF2CF(CF3)OCF2CF2CN.

[0229] The content of nitrogen-containing crosslinking sites in the polymer blend is 0.5 mol% to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

[0230] The content of nitrogen-containing crosslinking sites can be measured by infrared spectroscopy (IR).

[0231] The content of nitrogen-containing crosslinkable groups in the polymer blend, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b), is preferably from 0.5 mol% to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less.

[0232] The content of the nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0233] The cyano group content in the polymer blend, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b), is preferably from 0.5 mol% to 3.0 mol%, more preferably 2.0 mol% or less, further preferably 1.5 mol% or less.

[0234] The cyano group content can be determined by infrared spectroscopy (IR).

[0235] When all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) are taken as 100 mol%, the content of monomer units having nitrogen-containing crosslinkable groups in the polymer blend is preferably from 0.5 mol% to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less.

[0236] The content of the monomer unit having a nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0237] When all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) are taken as 100 mol%, the content of the monomer units having a cyano group in the polymer blend is preferably from 0.5 mol% to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less.

[0238] The content of the monomer unit having a cyano group can be measured by infrared spectroscopy (IR).

[0239] When all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) are taken as 100 mol%, the content of the TFE unit and the FAVE unit in the polymer blend is preferably 97.0 mol% to 99.5 mol%, more preferably 98.0 mol% or more, and even more preferably 98.5 mol% or more.

[0240] (Method for producing polymer blend)

[0241] The polymer blend of the present invention can be produced by a production method of mixing a fluorinated elastomer (a) and a crystalline fluorinated polymer (b), or a production method of preparing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) by two-step polymerization.

[0242] The polymer blend of the present invention is preferably produced by preparing an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b), and precipitating the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion.

[0243] In the case of using a polymer blend obtained by a manufacturing method of mixing a solid matter of a fluoroelastomer (a) with a solid matter of a crystalline fluoropolymer (b), it is also possible to obtain an article having moderate hardness, small compression set at high temperature, and even after use under harsh conditions, the compression set is not easily increased. However, it is now found that, compared with a polymer blend obtained by a manufacturing method of mixing a solid matter of a fluoroelastomer (a) with a solid matter of a crystalline fluoropolymer (b), a polymer blend obtained by a manufacturing method of precipitating a fluoroelastomer (a) and a crystalline fluoropolymer (b) in an aqueous dispersion can provide an article having a smaller compression set at high temperature, and further suppressed increase in compression set after use under harsh conditions. The reason for this is not yet clear, but it is speculated that this is because the reaction of the nitrogen-containing cross-linking portion possessed by the fluoroelastomer (a) and the nitrogen-containing cross-linking portion possessed by the crystalline fluoropolymer (b) to form a co-crosslinked structure proceeds smoothly.

[0244] Examples of methods for preparing an aqueous dispersion containing a fluorinated elastomer (a) and a crystalline fluorinated polymer (b) include: a method of mixing an aqueous dispersion containing a fluorinated elastomer (a) with an aqueous dispersion containing a crystalline fluorinated polymer (b); a method of mixing a powder of the fluorinated elastomer (a) with an aqueous dispersion containing a crystalline fluorinated polymer (b); and a method of mixing an aqueous dispersion containing a fluorinated elastomer (a) with a powder of a crystalline fluorinated polymer (b). Among these, the method of mixing an aqueous dispersion containing a fluorinated elastomer (a) with an aqueous dispersion containing a crystalline fluorinated polymer (b) is preferred.

[0245] Methods for precipitating the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion include: mixing the aqueous dispersion with a precipitating agent; freezing the aqueous dispersion. As the precipitating agent, known precipitating agents such as acids can be used, for example, aluminum salts, calcium salts, or magnesium salts can be mentioned; organic precipitating agents such as ammonium acetate and ammonium carbonate can be mentioned; and inorganic acid precipitating agents such as hydrochloric acid, nitric acid, hydrofluoric acid, sulfuric acid, and trifluoroacetic acid can be mentioned.

[0246] The precipitate obtained by precipitation can be washed with water to remove a small amount of impurities such as buffer solution and salt in the precipitate, and then the washed precipitate can be dried using a hot air furnace, vacuum dryer, etc. to prepare the polymer blend.

[0247] The form of the polymer blend obtained after precipitation is not particularly limited and may be gum, crumb, powder, granules, etc., preferably gum or crumb. Gum is a granular small piece composed of the polymer blend, and crumb refers to the form in which the fluoroelastomer (a) in the polymer blend cannot maintain the small granular form as gum at room temperature and fuses with each other to form an amorphous block.

[0248] In the method for producing the polymer blend of the present invention, as a method for mixing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b), the following method is preferred:

[0249] (1-1) tetrafluoroethylene, fluoroalkyl vinyl ether and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a fluorinated elastomer (a);

[0250] (1-2) tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b);

[0251] (1-3) mixing an aqueous dispersion containing the fluorinated elastomer (a) and an aqueous dispersion containing the crystalline fluorinated polymer (b) to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b),

[0252] (1-4) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated to obtain a polymer blend.

[0253] The aqueous dispersion containing the fluorinated elastomer (a) and the aqueous dispersion containing the crystalline fluorinated polymer (b) can be prepared by a known polymerization method.

[0254] In the method for producing the polymer blend of the present invention, as a method for producing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) by two-step polymerization, the following production method is preferred:

[0255] (2-1) Tetrafluoroethylene and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b);

[0256] (2-2) in the presence of a crystalline fluorinated polymer (b) and an aqueous medium, tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b);

[0257] (2-3) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated.

[0258] In the above production method, the polymerization in step (2-1) and the polymerization in step (2-2) may be carried out in the same reaction vessel or in different reaction vessels. When carried out in the same reaction vessel, the polymerization in step (2-2) may be started after stopping the polymerization in step (2-1), or the polymerization in step (2-2) may be started without stopping the polymerization in step (2-1).

[0259] In one embodiment of the above manufacturing method,

[0260] (2-1) In a reaction vessel, an aqueous dispersion containing a crystalline fluorinated polymer (b) is prepared,

[0261] (2-2) While continuing the polymerization reaction in the reaction vessel, fluoroalkyl vinyl ether is added to the reaction vessel to polymerize tetrafluoroethylene, fluoroalkyl vinyl ether, and the monomer having a nitrogen-containing crosslinkable group.

[0262] By producing a polymer blend through a continuous polymerization reaction in this manner, it is possible to produce a polymer blend that can impart appropriate hardness to an article and has a lower compression set at high temperatures, and further, can produce an article in which an increase in compression set after use under severe conditions is further suppressed.

[0263] The polymerization in step (2-1) and the polymerization in step (2-2) are preferably carried out using an emulsion polymerization method. In one embodiment, the polymerization is carried out in the presence of a polymerization initiator, a surfactant, and an aqueous medium.

[0264] Examples of the polymerization initiator include oil-soluble radical polymerization initiators and water-soluble radical initiators.

[0265] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, and for example, the following peroxides may be cited as representative substances: dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and di-sec-butyl peroxydicarbonate; peroxyesters such as tert-butyl peroxyisobutyrate and tert-butyl peroxypivalate; dialkyl peroxides such as di-tert-butyl peroxide; and di(ω-hydro-perfluorohexanoyl) peroxide, di(ω-hydro-dodecafluoroheptanoyl) peroxide, di(ω-hydro-tetrafluorooctanoyl) peroxide, di(ω-hydro-hexafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluorovaleranoyl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di( Typical examples include di[perfluoro(or fluorochloro)acyl]peroxides such as bis(perfluorooctanoyl)peroxide, bis(perfluorononanoyl)peroxide, bis(ω-chloro-hexafluorobutyryl)peroxide, bis(ω-chloro-decafluorohexanoyl)peroxide, bis(ω-chloro-tetrafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, bis(dichloropentafluorobutyryl)peroxide, bis(trichlorooctafluorohexanoyl)peroxide, bis(tetrachloroundecanoyl)peroxide, bis(pentachlorotetrafluorodecanoyl)peroxide, and bis(undecachlorotriadecanoyl)peroxide.

[0266] The water-soluble free radical polymerization initiator may be a known water-soluble peroxide, such as ammonium, potassium, or sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, or percarbonic acid, tert-butyl permaleate, or tert-butyl hydroperoxide. A reducing agent such as a sulfite may also be included, and its amount may be 0.1 to 20 times that of the peroxide.

[0267] The amount of polymerization initiator added is not particularly limited; it can be added all at once, sequentially, or continuously in the initial polymerization stage in an amount sufficient to not significantly reduce the polymerization rate (e.g., a concentration of several ppm relative to water). The upper limit is the range within which the heat of polymerization reaction can be removed from the apparatus.

[0268] As the surfactant, nonionic surfactants, anionic surfactants, cationic surfactants, etc. can be used. Fluorine-based surfactants used in International Publication No. 2000 / 029479, U.S. Patent Application Publication No. 2007 / 0015865, and Japanese Patent Application Laid-Open No. 2014-540475 can also be used. The amount added (relative to the solvent) is preferably 10 ppm to 20% by mass, more preferably 10 ppm to 10% by mass, further preferably 10 ppm to 7% by mass, and particularly preferably 50 ppm to 5% by mass.

[0269] Alternatively, a reactive emulsifier may be used as a surfactant. The reactive emulsifier is not particularly limited as long as it is a compound having one or more unsaturated bonds and a hydrophilic group. Examples thereof include CH2=CFCF2OCF(CF3)CF2OCF(CF3)COONH4, CH2=CFCF2CF(CF3)OCF2CF2COONH4, and CF2=CFOCF2CF(CF3)OCF(CF3)COONH4. The amount added (relative to the solvent) is preferably 10 to 5000 ppm by mass, more preferably 50 to 5000 ppm by mass.

[0270] Alternatively, a polymer of a compound having one or more unsaturated bonds and a hydrophilic group may be used instead of a surfactant. Examples of such polymers include homopolymers of compounds such as CH2=CFCF2OCF(CF3)CF2OCF(CF3)COONH4, CH2=CFCF2CF(CF3)OCF2CF2COONH4, and CF2=CFOCF2CF(CF3)OCF(CF3)COONH4. The amount added (relative to the solvent) is preferably 10 mass ppm to 10 mass %, more preferably 50 mass ppm to 5 mass %, and even more preferably 50 mass ppm to 2 mass %.

[0271] The aqueous medium is preferably a medium that does not have chain transfer properties. Examples of the aqueous medium include water, a mixture of water and a water-soluble organic solvent, and a mixture of water and a water-insoluble organic solvent.

[0272] In addition, polymerization can also be carried out in the presence of a chain transfer agent. As a chain transfer agent, in addition to the above-mentioned nitrogen-containing chain transfer agent, an iodine compound or a bromine compound can also be used. As a polymerization method using an iodine compound or a bromine compound to carry out, for example, a method (iodine transfer polymerization method) in which emulsion polymerization is carried out in an aqueous medium while pressurizing under a substantially oxygen-free state and in the presence of an iodine compound or a bromine compound can be enumerated. As a representative example of the iodine compound or bromine compound used, for example, general formula can be enumerated:

[0273] R21 I x Br y

[0274] (where x and y are integers from 0 to 2 and satisfy 1≤x+y≤2, R 21 is a saturated or unsaturated fluorocarbon or chlorofluorocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, wherein R 21 By using an iodine compound or a bromine compound, iodine atoms or bromine atoms are introduced into the polymer, thereby functioning as crosslinking points.

[0275] Examples of the iodine compound and the bromine compound include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodine-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodine-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodine-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluoro-1-butene, 2-bromo-4-iodoperfluoro-1-butene, monoiodinated and monobrominated substitutions of benzene, diiodinated and monobrominated substitutions, and (2-iodinated and (2-bromoethyl) substitutions, etc. These compounds can be used alone or in combination with each other.

[0276] Among these, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane are preferably used in view of polymerization reactivity, crosslinking reactivity, and availability.

[0277] The polymerization temperature, polymerization pressure, and polymerization time vary depending on the type of solvent and polymerization initiator, and may be -15°C to 150°C, atmospheric pressure to 12 MPa, and 1 to 24 hours. When an oil-soluble free radical polymerization initiator is used as the polymerization initiator, the polymerization temperature is preferably 30°C to 95°C. When a water-soluble free radical polymerization initiator is used as the polymerization initiator, the polymerization temperature is preferably 0°C to 100°C, more preferably 10°C to 95°C.

[0278] (Crosslinkable composition)

[0279] A crosslinkable composition can be prepared by mixing the polymer blend with at least one selected from the group consisting of an inorganic nitride, an organotin compound, an ammonia-generating compound, and a crosslinking agent. The polymer blend and the crosslinkable composition containing at least one selected from the group consisting of an inorganic nitride, an organotin compound, an ammonia-generating compound, and a crosslinking agent are crosslinked to produce an article (crosslinked product).

[0280] The inorganic nitride is not particularly limited, and examples thereof include silicon nitride (Si3N4), lithium nitride, titanium nitride, aluminum nitride, boron nitride, vanadium nitride, zirconium nitride, etc. Among these, silicon nitride is preferred because it can provide nano-level fine particles.

[0281] Examples of the organic tin compound include tetraphenyltin and triphenyltin.

[0282] As the compound that generates ammonia, a compound that generates ammonia at 40°C to 330°C is preferred.

[0283] The ammonia-generating compound is preferably urea or a derivative thereof, or an ammonium salt, more preferably urea or an ammonium salt, and even more preferably urea. The ammonium salt may be an organic ammonium salt or an inorganic ammonium salt. Furthermore, the ammonia-generating compound may be a substance that reacts with a trace amount of water to generate ammonia.

[0284] Examples of urea derivatives include diurea, thiourea, urea hydrochloride, and biuret.

[0285] Examples of the organic ammonium salt include ammonium salts of non-fluorinated carboxylic acids or sulfonic acids such as ammonium benzoate, ammonium adipate, and ammonium phthalate.

[0286] Examples of the inorganic ammonium salt include compounds described in Japanese Patent Application Laid-Open No. 9-111081, such as ammonium sulfate, ammonium carbonate, ammonium nitrate, and ammonium phosphate.

[0287] Examples of the ammonia-generating compound include acetaldehyde ammonia, hexamethylenetetramine, formamidine, formamidine hydrochloride, formamidine acetate, t-butyl carbamate, benzyl carbamate, and phthalamide.

[0288] Examples of the cross-linking agent include cross-linking agents used for peroxide cross-linking, polyol cross-linking, polyamine cross-linking, triazine cross-linking, oxazole cross-linking, imidazole cross-linking, and thiazole cross-linking.

[0289] The crosslinking agent used in the peroxide crosslinking may be any organic peroxide that can readily generate peroxide radicals in the presence of heat or a redox system. Specific examples thereof include 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-tert-butyl peroxide (Perbutyl D), tert-butylcumyl peroxide (Perbutyl C), dicumyl peroxide (Percumyl D, Percumyl D-40, Percumyl D-40MB(T)), α,α-bis(tert-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (Perhexa 25B, Perhexa 25B-40), 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne (Perhexyne 25B, Perhexyne 25B-40), benzoyl peroxide, tert-butylbenzene peroxide, 2,5-dimethyl-2,5-di(benzoylperoxide)hexane (Perhexa 25Z), tert-butyl permaleate (t-butyl MA), tert-butyl peroxyisopropyl carbonate (Perbutyl I-75), methyl ethyl ketone peroxide (Permek D (DR), Permek H (HR, HY), Permek N (NR, NY), Permek S (SR), Permek F (FR), Permek G (GR, GY)), cyclohexanone peroxide (Perhexa H), acetylacetone peroxide (Percure AH, AL), 1,1-di(tert-hexylperoxy)-3,3,5-trimethylcyclohexane (Perhexa TMH), 1,1-di(tert-hexylperoxy)cyclohexane (Perhexa HC), 1,1-di(tert-butylperoxy)-2-methylcyclohexane (Perhexa MC), 1,1-di(tert-butylperoxy)cyclohexane (Perhexa C-80(S), Perhexa C-75(EB), Perhexa C(C), Perhexa C-40, Perhexa C-40MB(S)), 2,2-di(tert-butylperoxy)butane (Perhexa 22), 4,4-di(tert-butylperoxy)butyl valerate (Perhexa V, Perhexa V-40(F)), 2,2-bis(4,4-di(tert-butylperoxy)cyclohexyl)propane (Pertetra A), terpane hydroperoxide (Permenta H), diisopropylbenzene hydroperoxide (Percumyl P), 1,1,3,3-Tetramethylbutyl hydroperoxide (Perocta H), cumene hydroperoxide (Percumyl H-80), tert-butyl hydroperoxide (Perbutyl H-69), di(2-tert-butylperoxyisopropyl)benzene (Perbutyl P, Perbutyl P-40, Peroximon F-40, Perbutyl P-40MB(K)), di-tert-hexyl peroxide (Perhexyl D), diisobutyryl peroxide (Peroyl IB), di(3,5,5-trimethylhexanoyl) peroxide (Peroyl 355(S)), dilauroyl peroxide (Peroyl L), succinyl peroxide (Peroyl SA), di(3-methylbenzoyl) peroxide, benzoyl(3-methylbenzoyl) peroxide and polymer blends of dibenzoyl peroxide (NYPER BMT-K40, NYPER BMT-M), dibenzoyl peroxide (NYPER BW, NYPERBO, NYPER Peroyl FF, NYPERBS, NYPER E, NYPER NS), di(4-methylbenzoyl) peroxide (NYPER PMB), di-n-propyl peroxydicarbonate (Peroyl NPP-50M), diisopropyl peroxydicarbonate (Peroyl IPP-50, Peroyl IPP-27), di(4-tert-butylcyclohexyl) peroxydicarbonate (Peroyl TCP), di(2-ethylhexyl) peroxydicarbonate (Peroyl OPP), di-sec-butyl peroxydicarbonate (Peroyl SBP), cumyl peroxyneodecanoate (Percumyl ND, Percumyl ND-50E), 1,1,3,3-tetramethylbutyl peroxyneodecanoate (Perocta ND, Perocta ND-50E), tert-hexyl peroxyneodecanoate (Perhexyl ND, Perhexyl ND-50E), tert-butyl peroxyneodecanoate (Perbutyl ND, Perbutyl ND-50E), tert-butyl peroxyneoheptanoate (Perbutyl NHP), tert-hexyl peroxypivalate (Perhexyl PV, Perhexyl PV-50E), tert-butyl peroxypivalate (PerbutylPV, Perbutyl PV-40E), 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (Perocta O), 2,5-dimethyl-2,5-Di(2-ethylhexanoylperoxy)hexane (Perhexa 25O), tert-hexyl peroxy(2-ethyl)hexanoate (PerhexylO, Percure HO(N)), tert-butyl peroxy(2-ethylhexanoate) (Perbutyl O, Percure O), tert-hexyl peroxyisopropyl monocarbonate (Perhexyl I), tert-butyl peroxy-3,5,5-trimethylhexanoate (Perbutyl355), tert-butyl peroxylaurate (Perbutyl L), tert-butyl peroxy-2-ethylhexyl monocarbonate (Perbutyl E), tert-hexyl peroxybenzoate (Perhexyl Z), tert-butyl peroxyacetate (Perbutyl A), polymer blend of tert-butyl peroxy-3-methylbenzoate and tert-butyl peroxybenzoate (Perbutyl ZT), tert-butyl peroxybenzoate (Perbutyl Z), tert-butyl peroxyallyl monocarbonate (Peromer AC), 3,3',4,4'-tetrakis(tert-butylperoxycarbonyl)benzophenone (BTTB-25), 2,3-dimethyl-2,3-diphenylbutane (NOFMER BC-90), etc. Among them, dialkyl-type substances are preferred. In addition, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane is particularly preferred. Generally, the type and amount of organic peroxide are selected based on the amount of active -OO- and decomposition temperature.

[0290] In addition, as a cross-linking auxiliary agent that can be used at this time, any compound that is reactive with peroxide radicals and polymer radicals can be used, and examples include polyfunctional compounds having functional groups such as -CH=CH2, -CH2CH=CH2, -CF=CF2, -C(CF3)=CF2, -C(CH3)=CF2, -CF=CF(CF3), -CF=CF(CH3), -C(C6H5)=CF2, -CF=CF(C6H5), -CH=CF2, -CF=CHF, -C(CF3)=CHF, -CF=CH(CF3), and -CH=CF(CF3) ("C6H5" in each formula represents a phenyl group). Specific examples include triallyl cyanurate, triallyl isocyanurate (TAIC), 1,3,5-triacryloylhexahydro-1,3,5-triazine, triallyl trimellitate, N,N'-n-phenylenebismaleimide, diallyl terephthalate, diallyl phthalate, tetraallyl terephthalamide, triallyl phosphate, bismaleimide, fluorinated triallyl isocyanurate (1,3,5-tris(2,3,3-trifluoro-2-propenyl)-1,3,5-triazine-2,4,6-trione), tris(diallylamine)-s-triazine, triallyl phosphite, N,N-diallylacrylamide, and 1,6-divinyldodecafluorohexane.

[0291] In addition, as a crosslinking auxiliary agent used together with the peroxide crosslinking agent, the general formula (31) can also be mentioned:

[0292] [Chemistry 1]

[0293]

[0294] (Where, 6 R 31 are each independently H, a halogen atom, or an optionally halogenated group having 1 to 5 carbon atoms which may be interposed with an ether bond, 31 It is a compound represented by a linear or branched, optionally halogenated, alkylene, cycloalkylene, or (per)fluoropolyoxyalkylene group having 1 to 18 carbon atoms and optionally containing a heteroatom.

[0295] Examples of the compound represented by the general formula (31) include the compound represented by the general formula (32), the compound represented by the general formula (33), and the compound represented by the general formula (34).

[0296] General formula (32):

[0297] [Chemistry 2]

[0298]

[0299] (wherein, j is an integer of 2 to 10, preferably an integer of 4 to 8, and 4 R 32 Each independently represents H, F, or an alkyl group or a (per)fluoroalkyl group having 1 to 5 carbon atoms)

[0300] General formula (33):

[0301] [Chemistry 3]

[0302]

[0303] (Where Y 31 are each independently F, Cl or H, Y 32 Each independently represents F, Cl, H or OR 33 (Here, R 33 is a branched or linear alkyl group which may be substantially or completely fluorinated or chlorinated), Z 33 is a divalent group having 2 to 10 carbon atoms which may be interposed with an ether bond and may be fluorinated, preferably Z 33 -(CF2) where m is an integer from 3 to 5 m - group, the compound represented by the general formula (33) is preferably F2C=CF-O-(CF2)5-O-CF=CF2)

[0304] General formula (34):

[0305] [Chemistry 4]

[0306]

[0307] (Where Y 31 、Y 32 and Z 33 As mentioned above, R 34 Each independently represents H, F, or an alkyl group or a (per)fluoroalkyl group having 1 to 5 carbon atoms)

[0308] As a crosslinking auxiliary agent used together with a crosslinking agent or a peroxide crosslinking agent, there can also be mentioned at least one compound having the general formula (35):

[0309] [Chemistry 5]

[0310]

[0311] (Where R 35 ~R 37 are each independently a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, or a substituted or unsubstituted aryl group, R 35 ~R 37 At least one of them is a fluorine atom or a group containing a fluorine atom. m is an integer from 1 to 5. When m is 2 or more, m R 35 ~R 37 They may be the same or different. A compound having a structure represented by (wherein the hydrogen atoms of the benzene ring may or may not have a substituent). When m is 1, it is preferred that there are two or more of the structure.

[0312] Examples of the compound having a structure represented by the general formula (36) include the compound represented by the general formula (36), the compound represented by the general formula (37), and the like.

[0313] General formula (36):

[0314] [Chemistry 6]

[0315]

[0316] (Where R 35 ~R 37 As described above. p is an integer from 0 to 2, and n is an integer from 2 to 6)

[0317] General formula (37):

[0318] [Chemistry 7]

[0319]

[0320] (Where R 35 ~R 37 As mentioned above.38 (a) is a single bond, -SO2-, -O-, -S-, -CO-, a heteroatom-containing group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group. m is an integer from 1 to 5. These groups may be partially or fully fluorinated.

[0321] The heteroatom-containing group is not particularly limited as long as it is a divalent group containing a heteroatom. Examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, a boron atom, and a phosphorus atom.

[0322] Examples of the crosslinking agent used for the polyol crosslinking include polyol compounds such as bisphenol A and bisphenol AF.

[0323] Examples of the crosslinking agent used for the polyamine crosslinking include polyamine compounds such as 1,6-hexanediamine carbamate, N,N′-dicinnamylene-1,6-hexanediamine, and 4,4′-bis(aminocyclohexyl)methane carbamate.

[0324] Examples of crosslinking agents used in oxazole crosslinking, imidazole crosslinking, and thiazole crosslinking include bisdiaminophenyl crosslinking agents represented by general formula (41), diaminophenol crosslinking agents, bisaminothiophenol crosslinking agents, bisaminohydrazone crosslinking agents represented by general formula (42), bisaminohydrazone crosslinking agents represented by general formula (43), bisamide oxime crosslinking agents represented by general formula (44), and compounds represented by general formula (45).

[0325] General formula (41):

[0326] [Chemistry 8]

[0327]

[0328] (Where R 41 is -SO2-, -O-, -CO-, an alkylene group having 1 to 6 carbon atoms, a perfluoroalkylene group having 1 to 10 carbon atoms, or a single bond, or

[0329] [Chemistry 9]

[0330]

[0331] The group shown, R 42 and R 43 One of them is -NH2 and the other is -NHR 44 , -NH2, -OH or -SH, R 44 is a hydrogen atom, a fluorine atom or a monovalent organic group, preferably R 42 -NH2, R 43 NHR 44Preferred specific examples of the alkylene group having 1 to 6 carbon atoms include methylene, ethylene, propylene, butylene, pentylene, and hexylene. Preferred specific examples of the perfluoroalkylene group having 1 to 10 carbon atoms include

[0332] [Chemistry 10]

[0333]

[0334] It should be noted that these compounds are known as examples of bisdiaminophenyl compounds in Japanese Patent Publication No. 2-59177, Japanese Patent Publication No. 8-120146, etc.)

[0335] General formula (42):

[0336] [Chemistry 11]

[0337]

[0338] (R 41 As mentioned above, R 45 Each independently represents any one of the following groups)

[0339] [Chemistry 12]

[0340]

[0341] General formula (43):

[0342] [Chemistry 13]

[0343]

[0344] (Where Rf 41 is a perfluoroalkylene group having 1 to 10 carbon atoms)

[0345] General formula (44):

[0346] [Chemistry 14]

[0347]

[0348] (where n is an integer from 1 to 10)

[0349] General formula (45): HN=CR 45 R 46

[0350] (Where R 45 Selected from H, NH2 and NHR 47 In the group composed of 46 Selected from Ph, SO2H, NR 48 R 49, 2-pyridine and CH2CONH2, R 47 Selected from the group consisting of Ph, NH2 and CN, R 48 is selected from the group consisting of H, NHPh, CH2CONH2, a linear alkyl group having 1 to 8 carbon atoms, and a branched alkyl group having 1 to 8 carbon atoms, and R 49 Selected from Ph, COOC(CH3)3, NH2, CH2COOH, CSNH2, CNHNH3 + Cl - , p-phenyl CN,

[0351] [Chemistry 15]

[0352]

[0353] and COPh)

[0354] In addition, as a cross-linking agent, the general formula (46) can also be mentioned: X 41 -(CH2) n -R 50 -(CH2) m -X 41 (Where, X 41 are each independently an alkynyl group, a nitrile group or Y 41 P N3(Y 41 is SO, SO2, C6H4 or CO, p is 0 or 1), n and m are independently integers of 1 to 4, R 50 Choose Free

[0355] i) a fluoroalkylene group having 3 to 10 carbon atoms,

[0356] ii) a fluoroalkyleneoxy group having 3 to 10 carbon atoms,

[0357] iii) substituted arylene groups,

[0358] iv) oligomers comprising copolymerized units of vinylidene fluoride and perfluoro(methyl vinyl ether),

[0359] v) an oligomer comprising copolymerized units of vinylidene fluoride and hexafluoropropylene,

[0360] vi) oligomers comprising copolymerized units of tetrafluoroethylene and perfluoro(methyl vinyl ether) and

[0361] vii) Crosslinking agents shown in the group consisting of oligomers comprising copolymerized units of tetrafluoroethylene and hydrocarbon olefins.

[0362] Particularly preferred crosslinking agents include compounds having two or more 3-amino-4-hydroxyphenyl groups or 3-amino-4-mercaptophenyl groups, or compounds of the general formula (47):

[0363] [Chemistry 16]

[0364]

[0365] (Where R 41 、R 42 and R 43 As described above), specifically, for example, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (common name: bis(aminophenol) AF), 2,2-bis(3-amino-4-mercaptophenyl)hexafluoropropane, tetraaminobenzene, bis-3,4-diaminophenylmethane, bis-3,4-diaminophenyl ether, 2,2-bis(3,4-diaminophenyl)hexafluoropropane, 2,2-bis[3-amino-4-(N-phenylamino) Hexafluoropropane, 2,2-bis[3-amino-4-(N-methylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-ethylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-propylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-perfluorophenylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-benzylamino)phenyl]hexafluoropropane, etc.

[0366] Among these, 2,2-bis[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane is preferred as the crosslinking agent from the viewpoints of heat resistance, steam resistance, amine resistance, and good crosslinking properties.

[0367] The content of at least one selected from the group consisting of an inorganic nitride, an organotin compound, an ammonia-generating compound, and a cross-linking agent is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, further preferably 0.2 parts by mass or more, particularly preferably 0.3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, further preferably 2.0 parts by mass or less, and particularly preferably 1.0 part by mass or less, based on 100 parts by mass of the polymer blend.

[0368] (Other ingredients)

[0369] The cross-linkable composition may contain other components besides the cross-linking agent.

[0370] As other components, fillers can be mentioned, for example.

[0371] As fillers, there can be mentioned imide-based fillers having an imide structure, such as polyimide, polyamide-imide, and polyetherimide; organic fillers made of engineering plastics, such as polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherketone, and polyoxybenzoate; metal oxide fillers such as silicon oxide, aluminum oxide, and yttrium oxide; metal carbides such as silicon carbide and aluminum carbide; metal nitride fillers such as silicon nitride and aluminum nitride; and inorganic fillers such as carbon black, aluminum fluoride, and carbon fluoride.

[0372] Among these, carbon black, aluminum oxide, silicon oxide, yttrium oxide, silicon carbide, silicon nitride, polyimide, and carbon fluoride are preferable from the viewpoint of shielding effects against various plasmas.

[0373] The above-mentioned inorganic fillers and organic fillers may be mixed alone or in combination of two or more.

[0374] In areas where high purity and non-polluting properties are not particularly required, conventional additives such as processing aids, plasticizers, colorants, etc. that are typically added to the composition as needed may be mixed, and one or more conventional crosslinking agents or crosslinking aids different from those mentioned above may also be mixed.

[0375] The crosslinkable composition may also contain an organic basic compound. Examples of the organic basic compound include:

[0376] Formula: CH3(CH2) 17 -NH2-octadecylamine;

[0377] Formula: H2N-C(O)-(CH2) 11 -Erucamide of CH=CH-(CH2)7CH3;

[0378] Oleamide of formula: H2N-C(O)-(CH2)7-CH=CH-(CH2)7CH3;

[0379] Formula: H2N-(CH2)6-NH2 1,6-hexanediamine

[0380] Mode:

[0381] [Chemistry 17]

[0382] 1,8-diazabicycloundec-7-ene (DBU), etc.

[0383] The crosslinkable composition can be prepared by mixing the polymer blend with other components such as a crosslinking agent. Mixing can be performed using conventional polymer processing machinery such as an open roll mill, a Banbury mixer, a kneader, or an internal mixer.

[0384] The cross-linkable composition can be suitably used as a molding material for obtaining an article by cross-linking molding.

[0385] (thing)

[0386] The article of the present invention is obtained by crosslinking the crosslinkable composition. The article of the present invention has appropriate hardness, low compression set at high temperatures, and is unlikely to increase in compression set even after use under severe conditions.

[0387] Furthermore, the present invention provides an article having a compression set of 50% or less after being stored at 300°C for 70 hours, a compression set of less than 50% after being stored at 200°C for 70 hours, and a hardness of 65 or greater as measured according to ASTM D2240. The article of the present invention has moderate hardness, low compression set at high temperatures, and is less likely to increase in compression set even after use under harsh conditions. The article of the present invention, characterized by compression set and hardness, preferably contains a polymer. The polymer is preferably a blend of the above-mentioned polymers.

[0388] Hereinafter, both an article obtained by crosslinking the crosslinkable composition and an article characterized by compression set and hardness will be described.

[0389] The hardness (Shore A, peak) of the article is preferably 65 or higher, more preferably 67 or higher. The upper limit of the hardness is not particularly limited and may be 90 or lower, or 80 or lower. The hardness of the article can be measured in accordance with JIS K6253.

[0390] Thus, the article of the present invention has an appropriate hardness. Therefore, when the article of the present invention is used as a sealing material, for example, the article is not easily crushed even when tightened strongly, and is not easily cracked even when used at high temperatures. If the hardness of the article is too low, it is difficult to tighten strongly, or it is easy to crack when used at high temperatures. If the hardness is too high, it is difficult to compress the article, and therefore it may be difficult to obtain excellent sealing properties.

[0391] The compression set (300°C) of an article measured after storage at 300°C for 70 hours is preferably 50% or less, more preferably 45% or less, even more preferably 40% or less, and even more preferably 35% or less. The compression set (300°C) can be calculated by compressing an article at a compression ratio of 25%, storing it at 300°C for 70 hours, releasing the compression, and storing it at 23°C for 30 minutes. The thickness of the article before and after compression is then measured.

[0392] As described above, the article of the present invention has a small compression set even when used at a high temperature exceeding 300°C.

[0393] The compression set (200°C) of an article measured after storage at 200°C for 70 hours is preferably less than 50%, more preferably 45% or less, and even more preferably 40% or less. The compression set (200°C) can be calculated by compressing the article at a compression ratio of 25%, storing it at 200°C for 70 hours, then storing it at 70°C for 270 hours, releasing the compression, and storing it at 20°C for 30 minutes. The thickness of the compressed article is then measured and calculated.

[0394] In this way, the article of the present invention is unlikely to increase in compression set even after use under harsh conditions. For example, when the article of the present invention is used as a sealing material for a semiconductor manufacturing device, the sealing material is sometimes used in a compressed state at a temperature of 200°C or above when the semiconductor manufacturing device is in operation. Afterwards, if the operation of the semiconductor manufacturing device is stopped, the sealing material is slowly cooled to room temperature in a compressed state and then left at room temperature. Therefore, the sealing material is required to have properties that can withstand use under such harsh conditions. The article of the present invention has excellent high-temperature sealing properties and low-temperature sealing properties and can withstand use under such harsh conditions.

[0395] Examples of methods for obtaining articles from crosslinkable compositions include forming the crosslinkable composition into a molding material to obtain a preform, and then crosslinking the preform. The method for obtaining a preform from a crosslinkable composition can be conventional, and can be performed by known methods such as heating and compressing the composition using a mold, pressing the composition into a heated mold, or extruding the composition using an extruder. In the case of extruded products such as hoses and wires, the article can be obtained by heating and crosslinking the composition using steam or the like after extrusion.

[0396] The above crosslinking is referred to as primary crosslinking and can be performed in the order of primary crosslinking and secondary crosslinking. The primary crosslinking is preferably performed at 150°C to 250°C for 5 to 120 minutes, more preferably at 170°C to 200°C for 5 to 60 minutes. As the crosslinking means, known crosslinking means can be used, for example, press crosslinking.

[0397] The secondary crosslinking is preferably carried out at 250°C to 320°C for 2 hours to 48 hours, more preferably at 280°C to 310°C for 5 hours to 24 hours. In addition, the secondary crosslinking can be carried out at 180°C to 320°C for 2 hours to 24 hours, or at 190°C to 310°C for 5 hours to 20 hours. The temperature can also be varied within this temperature range. As the crosslinking means, known crosslinking means can be used, for example, heat crosslinking can be mentioned. Crosslinking can be carried out, for example, in an air atmosphere or a nitrogen atmosphere.

[0398] The article of the present invention can be suitably used as a sealing material for semiconductor manufacturing equipment that particularly requires heat resistance, particularly semiconductor manufacturing equipment subjected to high-density plasma irradiation. Examples of such sealing materials include O-rings, square rings, gaskets, packings, oil seals, bearing seals, and lip seals.

[0399] In addition, it can be used as various polymer products used in semiconductor manufacturing equipment, such as diaphragms, tubes, hoses, various rubber rollers, belts, etc. It can also be used as a coating material or a lining material.

[0400] It should be noted that the semiconductor manufacturing equipment referred to in the present invention is not particularly limited to equipment for manufacturing semiconductors, but broadly includes all manufacturing equipment used in the semiconductor field that requires high cleanliness, such as equipment for manufacturing liquid crystal panels or plasma panels, for example, the following equipment can be cited.

[0401] (1) Etching equipment

[0402] Dry etching equipment

[0403] Plasma etching equipment

[0404] Reactive ion etching equipment

[0405] Reactive ion beam etching equipment

[0406] Sputtering etching equipment

[0407] Ion beam etching equipment

[0408] Wet etching equipment

[0409] Ashing device

[0410] (2) Cleaning device

[0411] Dry etching cleaning equipment

[0412] UV / O3 cleaning device

[0413] Ion beam cleaning device

[0414] Laser beam cleaning device

[0415] Plasma cleaning device

[0416] Gas etching cleaning device

[0417] Extraction and cleaning device

[0418] Soxhlet extraction cleaning device

[0419] High temperature and high pressure extraction and cleaning device

[0420] Microwave extraction and cleaning device

[0421] Supercritical extraction cleaning device

[0422] (3) Exposure device

[0423] photolithography machine

[0424] Coating machine and developer

[0425] (4) Grinding device

[0426] CMP equipment

[0427] (5) Film forming device

[0428] CVD equipment

[0429] Sputtering device

[0430] (6) Diffusion and ion implantation equipment

[0431] Oxidation diffusion device

[0432] Ion implantation equipment

[0433] The article of the present invention can exhibit excellent performance as a sealing material for, for example, a CVD apparatus, a plasma etching apparatus, a reactive ion etching apparatus, an ashing apparatus, or an excimer laser exposure apparatus.

[0434] While the embodiments have been described above, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the claims.

[0435] <1> According to a first aspect of the present invention, there is provided a polymer blend comprising a fluorinated elastomer (a) and a crystalline fluorinated polymer (b), wherein:

[0436] The fluorinated elastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units and nitrogen-containing crosslinking sites.

[0437] The crystalline fluorinated polymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking sites,

[0438] The melting point of the above polymer blend is 310℃~320℃,

[0439] The content of the crystalline fluorinated polymer (b) in the polymer blend is from 4.0 to 15.0 mass % based on the total mass of the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

[0440] <2> According to a second aspect of the present invention, there is provided the polymer blend according to the first aspect, wherein the polymer blend has a Mooney viscosity of 70 to 120 at 170°C.

[0441] <3> According to a third aspect of the present invention, there is provided a polymer blend according to the first aspect or the second aspect, wherein the content of nitrogen-containing crosslinking sites in the polymer blend is 0.5 mol% to 3.0 mol%, based on 100 mol% of all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

[0442] <4> According to a fourth aspect of the present invention, there is provided a polymer blend according to any one of the first to third aspects, wherein the content ratio of tetrafluoroethylene units to fluoroalkyl vinyl ether units in the polymer blend is 50 / 50 to 70 / 30 in terms of a molar ratio (tetrafluoroethylene units / fluoroalkyl vinyl ether units).

[0443] <5> According to a fifth aspect of the present invention, there is provided the polymer blend according to any one of the first to fourth aspects, wherein the fluoroalkyl vinyl ether units in the fluorinated elastomer (a) are perfluoro(methyl vinyl ether) units.

[0444] <6> According to a sixth aspect of the present invention, there is provided a polymer blend according to any one of the first to fifth aspects, wherein the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) contain monomer units having nitrogen-containing crosslinkable groups.

[0445] <7> According to the seventh aspect of the present invention, there is provided a polymer blend based on any one of the first to sixth aspects, which is obtained by a manufacturing method comprising preparing an aqueous dispersion containing a fluorinated elastomer (a) and a crystalline fluorinated polymer (b) and precipitating the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion.

[0446] <8> According to an eighth aspect of the present invention, there is provided a polymer blend according to any one of the first to seventh aspects, which is obtained by the following production method:

[0447] (1-1) tetrafluoroethylene, fluoroalkyl vinyl ether and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a fluorinated elastomer (a);

[0448] (1-2) tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b);

[0449] (1-3) mixing an aqueous dispersion containing the fluorinated elastomer (a) and an aqueous dispersion containing the crystalline fluorinated polymer (b) to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b),

[0450] (1-4) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated to obtain the polymer blend.

[0451] <9> According to a ninth aspect of the present invention, there is provided a polymer blend according to any one of the first to eighth aspects, wherein the content of nitrogen-containing crosslinking sites in the fluorinated elastomer (a) is 0.5 to 3.0 mol % when all monomer units constituting the fluorinated elastomer (a) are taken as 100 mol %.

[0452] <10> According to a tenth aspect of the present invention, there is provided a polymer blend based on any one of the first to ninth aspects, wherein the content of nitrogen-containing crosslinking sites in the crystalline fluorinated polymer (b) is 0.5 to 3.0 mol % when all monomer units constituting the crystalline fluorinated polymer (b) are taken as 100 mol %.

[0453] <11> According to an eleventh aspect of the present invention, there is provided a polymer blend according to any one of the first to seventh aspects, which is obtained by the following production method:

[0454] (2-1) Tetrafluoroethylene and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b);

[0455] (2-2) in the presence of a crystalline fluorinated polymer (b) and an aqueous medium, tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b);

[0456] (2-3) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated.

[0457] <12> According to a twelfth aspect of the present invention, there is provided a crosslinkable composition comprising the polymer blend according to any one of the first to eleventh aspects and at least one selected from the group consisting of an inorganic nitride, an organotin compound, an ammonia-generating compound, and a crosslinking agent.

[0458] <13> According to a thirteenth aspect of the present invention, there is provided an article obtained by crosslinking the crosslinkable composition according to the twelfth aspect.

[0459] <14> According to a fourteenth aspect of the present invention, there is provided an article according to the thirteenth aspect, wherein:

[0460] The compression set of the above article measured after being placed at 300°C for 70 hours is less than 50%.

[0461] The above article has a compression set of less than 50% after being placed at 200°C for 70 hours or at 70°C for 70 hours.

[0462] The hardness of the above article measured according to ASTM D2240 is 65 or more.

[0463] <15> According to a fifteenth aspect of the present invention, there is provided a production method for a polymer blend according to any one of the first to tenth aspects, wherein:

[0464] (1-1) tetrafluoroethylene, fluoroalkyl vinyl ether and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a fluorinated elastomer (a);

[0465] (1-2) tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b);

[0466] (1-3) mixing an aqueous dispersion containing the fluorinated elastomer (a) and an aqueous dispersion containing the crystalline fluorinated polymer (b) to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b),

[0467] (1-4) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated to obtain the polymer blend.

[0468] <16> According to a sixteenth aspect of the present invention, there is provided a production method for a polymer blend according to any one of the first to seventh aspects and the eleventh aspect, wherein:

[0469] (2-1) Tetrafluoroethylene and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b);

[0470] (2-2) in the presence of a crystalline fluorinated polymer (b) and an aqueous medium, tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b);

[0471] (2-3) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated to obtain the polymer blend.

[0472] <17> According to a seventeenth aspect of the present invention, there is provided a manufacturing method according to the sixteenth aspect, wherein:

[0473] (2-1) In a reaction vessel, an aqueous dispersion containing a crystalline fluorinated polymer (b) is prepared,

[0474] (2-2) While continuing the polymerization reaction in the reaction vessel, fluoroalkyl vinyl ether is added to the reaction vessel to polymerize tetrafluoroethylene, fluoroalkyl vinyl ether, and the monomer having a nitrogen-containing crosslinkable group.

[0475] <18> According to an eighteenth aspect of the present invention, there is provided an article, wherein:

[0476] The compression set of the above article measured after being placed at 300°C for 70 hours is less than 50%.

[0477] The above article has a compression set of less than 50% after being placed at 200°C for 70 hours or at 70°C for 70 hours.

[0478] The hardness of the above article measured according to ASTM D2240 is 65 or more.

[0479] Example

[0480] Next, embodiments of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0481] Each numerical value in the examples was measured by the following method.

[0482] (Mooney viscosity)

[0483] The Mooney viscosity (ML (1+20)) of the polymer blend and the fluoroelastomer was measured at 170° C. in accordance with JIS K6300 using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES.

[0484] (Monomer composition)

[0485] The monomer composition of polymer blends, fluoroelastomers and crystalline fluoropolymers is determined by19 The content of the cyano group-containing monomer unit was determined by the following method (IR).

[0486] (Cyanide content and content of cyanide-containing monomer units)

[0487] The cyano content and the content of cyano-containing monomer units of the polymer blends, fluoroelastomers and crystalline fluoropolymers were determined by infrared spectroscopy (IR).

[0488] (Glass transition temperature)

[0489] The glass transition temperature of the polymer blend is determined as follows: Using a differential scanning calorimeter (manufactured by Hitachi High-Technologies Corporation, X-DSC7000), 3 mg of a sample is heated at 20°C / min to obtain a DSC curve. The temperature of the midpoint of the two intersections of the extended line representing the baseline before and after the secondary phase transition of the DSC curve and the tangent line at the inflection point of the DSC curve is determined and used as the above-mentioned glass transition temperature.

[0490] (Content of Crystalline Fluoropolymer (b))

[0491] The content of the crystalline fluorinated polymer (b) in the polymer blend is measured by weighing approximately 10 mg of the polymer blend that has not been heated to a temperature of 300°C or higher and placing it in a dedicated aluminum pan. The content is then measured using a TG / DTA (differential thermal gravimetric analysis). The aluminum pan is heated at a rate of 10°C / minute from 25°C to 600°C in an air atmosphere to obtain a TG curve. The weight loss rate is then calculated from the obtained TG curve to determine the content of the crystalline fluorinated polymer (b).

[0492] Table 1 shows the content of the crystalline fluorinated polymer (b) in the polymer blend relative to the total mass of the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

[0493] (Melting Point)

[0494] The melting point of the polymer blend is measured by weighing about 10 mg of the polymer blend that has not been heated to a temperature of 300°C or higher and placing it in a dedicated aluminum pan, and using TG / DTA (differential thermal and gravimetric simultaneous measurement apparatus). The aluminum pan is heated at a rate of 10°C / minute from 25°C to 600°C in an atmospheric atmosphere to obtain a DTA curve, and the temperature corresponding to the peak in the obtained DTA curve is determined as the melting point of the polymer blend. The presence or absence of a melting point of the fluoroelastomer is also confirmed using the method for determining the melting point of the polymer blend. In Table 1, "ND" indicates that no clear peak can be confirmed in the DTA curve.

[0495] (Hardness (Shore A) Peak)

[0496] Using a product having a thickness of 2 mm, the hardness (Shore A) (peak value) was measured in accordance with JIS-K6253.

[0497] (Compression set (300℃))

[0498] Compression set was measured according to ASTM D395 or JIS K6262. The O-rings prepared in Examples and Comparative Examples were compressed at room temperature using a compression device to a compression ratio of 25% (O-rings with a thickness (wire diameter) of 3.5 mm were compressed to a thickness of 2.625 mm).

[0499] Next, the compression device with the compressed O-ring fixed to it was placed in an electric furnace at 300°C for 70 hours, after which it was removed from the furnace. The O-ring was removed from the compression device and placed in a constant temperature chamber at 23°C for 30 minutes. The thickness (t2) of the O-ring was measured. The compression set was calculated using the following formula. The closer the compression set is to 0%, the better the compression set characteristics of the product.

[0500] Compression set (%) = (t0-t2) / (t0-t1)×100

[0501] t0: original thickness of the O-ring (mm)

[0502] t1: Thickness of spacer (mm)

[0503] t2: Thickness of the O-ring after compression test (mm)

[0504] In the above test, t0 = 3.5 mm, t1 = 2.625 mm.

[0505] (Compression set (200℃→70℃))

[0506] Compression set was measured according to ASTM D395 or JIS K6262. The O-rings prepared in Examples and Comparative Examples were compressed at room temperature using a compression device to a compression ratio of 25% (O-rings with a thickness (wire diameter) of 3.5 mm were compressed to a thickness of 2.625 mm).

[0507] Next, the compression device with the compressed O-ring fixed was placed in an electric furnace at 200°C for 70 hours, after which it was removed from the furnace. The compression device with the compressed O-ring fixed was then placed in another electric furnace at 70°C for 70 hours. The O-ring was removed from the compression device and placed in a constant temperature chamber at 23°C for 30 minutes. The thickness (t2) of the O-ring was measured. The compression set was calculated using the following formula.

[0508] Compression set (%) = (t0-t2) / (t0-t1)×100

[0509] t0: original thickness of the O-ring (mm)

[0510] t1: Thickness of spacer (mm)

[0511] t2: Thickness of the O-ring after compression test (mm)

[0512] In the above test, t0 = 3.5 mm, t1 = 2.625 mm.

[0513] Example 1

[0514] After adding 43g of ammonium perfluorohexanoate and 0.08g of ammonium carbonate to a 2L SUS autoclave, 790g of deionized, degassed water was added. The reaction vessel was sealed and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.33g of CF2=CFOCF2CF(CF3)OCF2CF2CN (CNVE) was added, and TFE was added until the pressure reached 0.29 MPa, maintaining the pressure and temperature. 3.0g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added to maintain a constant reaction pressure of 0.29 MPa, and a total of 0.27g of CNVE was continuously added until 25.0g of TFE was added. After the final addition of TFE, the pressure in the vessel dropped to 0.19 MPa, and 40.4g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 56.0 / 44.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 185.0 g of additional gas with a TFE / PMVE ratio of 56.0 / 44.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 4.7 g of CNVE was continuously added. When all the additional gas and CNVE had been added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 218 g of a polymer blend.

[0515] TG / DTA analysis of the resulting polymer blend revealed a melting point of 317.7°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 10.6% by weight. DSC analysis revealed a glass transition temperature of -4.6°C. NMR analysis revealed a TFE / PMVE ratio of 55.2 / 44.8 mol%, and IR analysis revealed a CNVE content of 0.57 mol%. The Mooney viscosity was 72.

[0516] Example 2

[0517] After adding 43g of ammonium perfluorohexanoate and 0.08g of ammonium carbonate to a 2L SUS autoclave, 790g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.16g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the vessel. 1.6g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added in such a way that the reaction pressure remained constant at 0.29MPa, and a total of 0.38g of CNVE was continuously added until 20.0g of TFE was added. After the final addition of TFE, the pressure in the vessel dropped to 0.19MPa, and 40.4g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 54.0 / 46.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 185.0 g of additional gas with a TFE / PMVE ratio of 54.0 / 46.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 4.7 g of CNVE was continuously added. When all the additional gas and CNVE were added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 213 g of a polymer blend.

[0518] TG / DTA analysis of the resulting polymer blend revealed a melting point of 316.5°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 9.4% by weight. Furthermore, DSC analysis revealed a glass transition temperature of -5.0°C. NMR analysis revealed a TFE / PMVE ratio of 53.5 / 46.5 mol%, and IR analysis revealed a CNVE content of 0.56 mol%. Furthermore, the Mooney viscosity was 86.

[0519] Example 3

[0520] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.65g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the vessel. 8.5g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added to maintain a constant reaction pressure of 0.29MPa, and a total of 0.65g of CNVE was added continuously until 34.0g of TFE was added. After the final addition of TFE, the pressure in the vessel dropped to 0.19MPa, and 145g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 660 g of additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 14.3 g of CNVE was continuously added. When all the additional gas and CNVE had been added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 718 g of a polymer blend.

[0521] TG / DTA analysis of the resulting polymer blend revealed a melting point of 313.7°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 5.5% by weight. DSC analysis revealed a glass transition temperature of -5.3°C. NMR analysis revealed a TFE / PMVE ratio of 58.6 / 41.4 mol%, and IR analysis revealed a CNVE content of 0.55 mol%. The Mooney viscosity was 90.

[0522] Example 4

[0523] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.54g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the tank. 5.4g of ammonium persulfate (APS) as a polymerization initiator was added. TFE was added in such a way that the reaction pressure remained constant at 0.29MPa, and a total of 0.65g of CNVE was continuously added until 34.0g of TFE was added. After the final addition of TFE, the pressure in the tank dropped to 0.19MPa, and 145g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 660 g of additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 14.3 g of CNVE was continuously added. When all the additional gas and CNVE were added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 700 g of a polymer blend.

[0524] TG / DTA analysis of the resulting polymer blend revealed a melting point of 314.3°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 5.0% by weight. Furthermore, DSC analysis revealed a glass transition temperature of -5.3°C. NMR analysis revealed a TFE / PMVE ratio of 58.9 / 41.1 mol%, and IR analysis revealed a CNVE content of 0.57 mol%. The Mooney viscosity was 115.

[0525] Example 5

[0526] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.54g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the tank. 9.2g of ammonium persulfate (APS) as a polymerization initiator was added. TFE was added so that the reaction pressure remained constant at 0.29MPa, and a total of 0.97g of CNVE was continuously added until 51.0g of TFE was added. After the final addition of TFE, the pressure in the tank dropped to 0.19MPa, and 145g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 660 g of additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 14.3 g of CNVE was continuously added. When all the additional gas and CNVE had been added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 730 g of a polymer blend.

[0527] TG / DTA analysis of the resulting polymer blend revealed a melting point of 314.4°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 7.6% by weight. DSC analysis revealed a glass transition temperature of -5.5°C. NMR analysis revealed a TFE / PMVE ratio of 58.1 / 41.9 mol%, and IR analysis revealed a CNVE content of 0.53 mol%. The Mooney viscosity was 87.

[0528] Example 6

[0529] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.54g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the tank. 7.2g of ammonium persulfate (APS) as a polymerization initiator was added. TFE was added in such a way that the reaction pressure remained constant at 0.29MPa, and a total of 0.97g of CNVE was continuously added until 51.0g of TFE was added. After the final addition of TFE, the pressure in the tank dropped to 0.19MPa, and 124g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 62.5 / 37.5 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 720 g of additional gas with a TFE / PMVE ratio of 62.5 / 37.5 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 14.3 g of CNVE was continuously added. When all the additional gas and CNVE had been added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 700 g of a polymer blend.

[0530] TG / DTA analysis of the resulting polymer blend revealed a melting point of 312.9°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 5.9% by weight. DSC analysis revealed a glass transition temperature of -4.1°C. NMR analysis revealed a TFE / PMVE ratio of 63.5 / 36.5 mol%, and IR analysis revealed a CNVE content of 0.55 mol%. The Mooney viscosity was 111.

[0531] Example 7

[0532] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 67.5°C, 0.54g of CNVE was added, and TFE was added until the pressure reached 0.36MPa, maintaining the pressure and temperature in the tank. 1.1g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added in such a way that the reaction pressure remained constant at 0.36MPa, and a total of 0.45g of CNVE was continuously added until 42.0g of TFE was added. After the final addition of TFE, the pressure in the tank dropped to 0.26MPa, and 115g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa. Then, additional gas (TFE / PMVE = 64.5 / 35.5 mol%) was introduced into the reaction vessel until the pressure reached 0.85 MPa. Subsequently, 724 g of additional gas (TFE / PMVE = 64.5 / 35.5 mol%) was continuously introduced to maintain a constant pressure of 0.85 MPa. Simultaneously, a total of 17.4 g of CNVE was continuously added. Furthermore, as the polymerization rate decreased, a 2 wt% aqueous solution of APS was added as appropriate. A total of 20 mL of the 2 wt% aqueous solution of APS was added after the start of polymerization. Once all the additional gas and CNVE had been added, stirring was stopped, and the pressure in the reaction vessel was depressurized until it reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid solution, washed with water, and vacuum dried at 70°C for 24 hours to yield 730 g of a polymer blend.

[0533] TG / DTA analysis of the resulting polymer blend revealed a melting point of 317.5°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 5.2% by weight. DSC analysis revealed a glass transition temperature of -2.6°C. NMR analysis revealed a TFE / PMVE ratio of 66.2 / 33.8 mol%, and IR analysis revealed a CNVE content of 0.61 mol%. The Mooney viscosity was 111.

[0534] Example 8

[0535] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 67.5°C, 0.54g of CNVE was added, and TFE was added until the pressure reached 0.36MPa, maintaining the pressure and temperature in the tank. 1.1g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added in such a way that the reaction pressure remained constant at 0.36MPa, and a total of 0.97g of CNVE was continuously added until 51.0g of TFE was added. After the final addition of TFE, the pressure in the tank dropped to 0.26MPa, and 115g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa. Then, additional gas (TFE / PMVE = 64.5 / 35.5 mol%) was introduced into the reaction vessel until the pressure reached 0.85 MPa. Subsequently, 724 g of additional gas (TFE / PMVE = 64.5 / 35.5 mol%) was continuously introduced to maintain a constant pressure of 0.85 MPa. Simultaneously, a total of 17.4 g of CNVE was continuously added. Furthermore, as the polymerization rate decreased, a 2 wt% aqueous solution of APS was added as appropriate. A total of 20 mL of the 2 wt% aqueous solution of APS was added after the start of polymerization. Once all the additional gas and CNVE had been added, stirring was stopped, and the pressure in the reaction vessel was depressurized until it reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid solution, washed with water, and vacuum dried at 70°C for 24 hours to yield 742 g of a polymer blend.

[0536] TG / DTA analysis of the resulting polymer blend revealed a melting point of 316.2°C, and the weight loss indicated a crystalline fluoropolymer (b) content of 7.2% by weight. Furthermore, DSC analysis revealed a glass transition temperature of -2.8°C. NMR analysis revealed a TFE / PMVE ratio of 66.6 / 33.4 mol%, and IR analysis revealed a CNVE content of 0.59 mol%. The Mooney viscosity was 108.

[0537] Comparative Example 1

[0538] After adding 43g of ammonium perfluorohexanoate and 0.08g of ammonium carbonate to a 2L SUS autoclave, 790g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.16g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the vessel. 1.6g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added to maintain a constant reaction pressure of 0.29MPa, and a total of 0.19g of CNVE was added continuously until 10.0g of TFE was added. After the final addition of TFE, the pressure in the vessel dropped to 0.19MPa, and 40.4g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 54.0 / 46.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 198 g of additional gas with a TFE / PMVE ratio of 54.0 / 46.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 5.0 g of CNVE was continuously added. When all the additional gas and CNVE were added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 213 g of a polymer blend.

[0539] TG / DTA analysis of the resulting polymer blend revealed no observed crystalline fluorinated polymer (b) content, as determined by the weight loss rate. Furthermore, DSC analysis revealed a glass transition temperature of -5.4°C. NMR analysis revealed a TFE / PMVE ratio of 54.4 / 45.6 mol%, and IR analysis revealed a CNVE ratio of 0.56 mol%. Furthermore, the Mooney viscosity was 96.

[0540] Comparative Example 2

[0541] After adding 155g of perfluorohexanoic acid ammonium salt and 0.28g of ammonium carbonate to a SUS autoclave with an internal volume of 6L, 2880g of deionized and degassed water was added. The reaction vessel was sealed, and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 2.24g of CNVE was added, and a mixed gas of TFE / PMVE = 24.0 / 76.0mol% was added until the pressure reached 0.85MPa, and the pressure and temperature in the tank were maintained. 15.0g of ammonium persulfate (APS) as a polymerization initiator was added. 810g of additional gas of TFE / PMVE = 58.0 / 42.0mol% was continuously introduced in such a way that the reaction pressure was constant at 0.85MPa. At the same time, a total of 25.6g of CNVE was continuously added. When all the additional gas and CNVE were added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was taken out of the reaction vessel and cooled. The obtained aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum-dried at 70° C. for 24 hours to obtain 828 g of a polymer blend.

[0542] TG / DTA analysis of the resulting polymer blend revealed no melting point, and the weight loss indicated that the crystalline fluoropolymer (b) content was 0 wt%. Furthermore, DSC analysis revealed a glass transition temperature of -5.2°C. NMR analysis revealed TFE / PMVE = 58.0 / 42.0 mol%, and IR analysis revealed CNVE = 1.20 mol%. Furthermore, the Mooney viscosity was 80.

[0543] Comparative Example 3

[0544] After adding 43g of ammonium perfluorohexanoate and 0.08g of ammonium carbonate to a 2L SUS autoclave, 790g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.64g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the vessel. 2.2g of ammonium persulfate (APS) as a polymerization initiator was added. TFE was added in such a way that the reaction pressure remained constant at 0.29MPa, and a total of 0.49g of CNVE was continuously added until 17.0g of TFE was added. After the final addition of TFE, the pressure in the vessel dropped to 0.19MPa, and 40.4g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 198 g of additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 4.7 g of CNVE was continuously added. When all the additional gas and CNVE had been added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 217 g of a polymer blend.

[0545] TG / DTA analysis of the resulting polymer blend revealed a melting point of 304.0°C, and the weight loss indicated that the crystalline fluoropolymer (b) content was 8.0% by weight. Furthermore, DSC analysis revealed a glass transition temperature of -5.0°C. NMR analysis revealed a TFE / PMVE ratio of 58.0 / 42.0 mol%, and IR analysis revealed a CNVE content of 0.58 mol%. Furthermore, the Mooney viscosity was 92.

[0546] Comparative Example 4

[0547] After adding 43g of ammonium perfluorohexanoate and 0.08g of ammonium carbonate to a 2L SUS autoclave, 790g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.16g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the vessel. 1.8g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added to maintain a constant reaction pressure of 0.29MPa, and a total of 0.08g of CNVE was added continuously until 22.0g of TFE was added. After the final addition of TFE, the pressure in the vessel dropped to 0.19MPa, and 40.4g of PMVE was added. After adding PMVE, the pressure was reduced to 0.735 MPa, and then additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was introduced into the reaction vessel until the pressure reached 0.85 MPa. Then, 188.0 g of additional gas with a TFE / PMVE ratio of 58.0 / 42.0 mol% was continuously introduced until the pressure remained constant at 0.85 MPa. At the same time, a total of 4.8 g of CNVE was continuously added. When all the additional gas and CNVE had been added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 213 g of a polymer blend.

[0548] TG / DTA analysis of the resulting polymer blend revealed a melting point of 328.0°C, and the weight loss indicated that the crystalline fluoropolymer (b) content was 10.0% by weight. Furthermore, DSC analysis revealed a glass transition temperature of -5.0°C. NMR analysis revealed a TFE / PMVE ratio of 58.0 / 42.0 mol%, and IR analysis revealed a CNVE content of 0.58 mol%. Furthermore, the Mooney viscosity was 86.

[0549] Synthesis Example of Fluoroelastomer (a)

[0550] After adding 155g of perfluorohexanoic acid ammonium salt and 0.28g of ammonium carbonate to a SUS autoclave with an internal volume of 6L, 2880g of deionized and degassed water was added. The reaction vessel was sealed, and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 1.21g of CNVE was added, and a mixed gas of TFE / PMVE = 24.0 / 76.0mol% was added until the pressure reached 0.85MPa, and the pressure and temperature in the tank were maintained. 15.0g of ammonium persulfate (APS) was added as a polymerization initiator. 810g of additional gas of TFE / PMVE = 58.0 / 42.0mol% was continuously introduced in such a way that the reaction pressure was constant at 0.85MPa. At the same time, a total of 19.8g of CNVE was continuously added. When all the additional gas and CNVE were added, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was taken out of the reaction vessel and cooled. A portion of the obtained aqueous dispersion was precipitated with aqueous nitric acid, washed with water, and vacuum-dried at 70° C. for 24 hours.

[0551] TG / DTA analysis of the obtained fluoroelastomer (a) revealed no melting point, and the weight loss indicated that the content of the crystalline fluoropolymer (b) was 0 wt%. Furthermore, NMR analysis indicated TFE / PMVE = 58.0 / 42.0 mol%, and IR analysis indicated CNVE = 0.60 mol%. Furthermore, the Mooney viscosity was 74.

[0552] Synthesis Example of Crystalline Fluoropolymer (b1)

[0553] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.54g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the tank. 5.4g of ammonium persulfate (APS) as a polymerization initiator was added. TFE was added in such a way that the reaction pressure remained constant at 0.29MPa, and a total of 0.65g of CNVE was continuously added until 34.0g of TFE was added. After the final addition of TFE was completed, the pressure in the tank was reduced to 0.19MPa, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. A portion of the obtained dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours.

[0554] IR analysis of the obtained crystalline fluorinated polymer (b1) revealed that CNVE was 0.90 mol%.

[0555] Synthesis Example of Crystalline Fluoropolymer (b2)

[0556] After adding 145g of ammonium perfluorohexanoate and 0.26g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.1g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the tank. 5.4g of ammonium persulfate (APS) as a polymerization initiator was added. TFE was added in such a way that the reaction pressure remained constant at 0.29MPa, and a total of 0.04g of CNVE was continuously added until 34.0g of TFE was added. After the final addition of TFE was completed, the pressure in the tank was reduced to 0.19MPa, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. A portion of the obtained dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours.

[0557] IR analysis of the obtained crystalline fluorinated polymer (b1) revealed that CNVE was 0.10 mol%.

[0558] Synthesis Example of Crystalline Fluoropolymer (b3)

[0559] After adding 145g of ammonium perfluorohexanoate and 2.16g of ammonium carbonate to a 6L SUS autoclave, 2660g of deionized and degassed water was added. The reaction vessel was sealed and the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, 0.54g of CNVE was added, and TFE was added until the pressure reached 0.29MPa, maintaining the pressure and temperature in the tank. 5.4g of ammonium persulfate (APS) as a polymerization initiator was added. TFE was added in such a way that the reaction pressure remained constant at 0.29MPa, and a total of 1.71g of CNVE was continuously added until 34.0g of TFE was added. After the final addition of TFE was completed, the pressure in the tank was reduced to 0.19MPa, stirring was stopped, and the pressure was removed until the reaction vessel reached atmospheric pressure. The aqueous dispersion was removed from the reaction vessel and cooled. A portion of the obtained dispersion was precipitated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours.

[0560] IR analysis of the obtained crystalline fluorinated polymer (b1) revealed that CNVE was 3.20 mol%.

[0561] Example 9

[0562] 995 g of an aqueous dispersion of a fluorinated elastomer (a) and 846 g of an aqueous dispersion of a fluorinated polymer (b1) were introduced into a container with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was precipitated with nitric acid, washed with water, and vacuum-dried at 70°C for 24 hours to obtain 220 g of a polymer blend. The obtained polymer blend was subjected to TG / DTA measurement, and the result showed that the melting point was 318°C. The content of crystalline fluorinated polymer (b) was 4.7% by weight as shown by the weight loss rate. In addition, according to DSC measurement, the glass transition temperature was -5.0°C. In addition, the Mooney viscosity was 86.

[0563] Example 10

[0564] 942 g of an aqueous dispersion of a fluoroelastomer (a) and 1692 g of an aqueous dispersion of a fluoropolymer (b1) were introduced into a container with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was precipitated with nitric acid, washed with water, and vacuum-dried at 70°C for 24 hours to obtain 220 g of a polymer blend. The obtained polymer blend was subjected to TG / DTA measurement, and the result showed that the melting point was 318°C. The content of crystalline fluoropolymer (b) was 11.2% by weight as shown by the weight loss rate. In addition, according to DSC measurement, the glass transition temperature was -5.0°C. In addition, the Mooney viscosity was 92.

[0565] Comparative Example 5

[0566] 890 g of an aqueous dispersion of a fluorinated elastomer (a) and 2538 g of an aqueous dispersion of a fluorinated polymer (b1) were introduced into a container equipped with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was precipitated with nitric acid, washed with water, and vacuum dried at 70°C for 24 hours to obtain 220 g of a polymer blend. The obtained polymer blend was subjected to TG / DTA measurement, and the results showed that the melting point was 318°C. The weight loss rate showed that the content of crystalline fluorinated polymer (b) was 15.7% by weight. In addition, according to DSC measurement, the glass transition temperature was -4.8°C. In addition, the Mooney viscosity was 92.

[0567] Comparative Example 6

[0568] 953 g of an aqueous dispersion of a fluoroelastomer (a) and 1523 g of an aqueous dispersion of a fluoropolymer (b2) were introduced into a container with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was precipitated with nitric acid, washed with water, and vacuum-dried at 70°C for 24 hours to obtain 220 g of a polymer blend. The obtained polymer blend was subjected to TG / DTA measurement, and the results showed that the melting point was 328°C. The weight loss rate showed that the content of crystalline fluoropolymer (b) was 10.2% by weight. In addition, according to DSC measurement, the glass transition temperature was -4.8°C. In addition, the Mooney viscosity was 82.

[0569] Comparative Example 7

[0570] 963 g of an aqueous dispersion of a fluoroelastomer (a) and 1353 g of an aqueous dispersion of a fluoropolymer (b2) were introduced into a container with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was precipitated with nitric acid, washed with water, and vacuum-dried at 70°C for 24 hours to obtain 220 g of a polymer blend. The obtained polymer blend was subjected to TG / DTA measurement, and the result showed that the melting point was 299°C. The weight loss rate showed that the content of crystalline fluoropolymer (b) was 8.2% by weight. In addition, according to DSC measurement, the glass transition temperature was -4.9°C. In addition, the Mooney viscosity was 87.

[0571] 0.9 parts by mass of 2,2-bis[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane (a), a crosslinking agent, was added to 100 parts by mass of the fluoroelastomer (a) in the polymer blends prepared in the Examples and Comparative Examples. The mixtures were kneaded using an open roll mill, pressed at 180°C for 30 minutes for crosslinking, and then oven-crosslinked in an air oven at 290°C for 18 hours to produce 2 mm thick sheets and P24 size O-rings. The resulting sheets were used to measure hardness, and the resulting O-rings were used to measure compression set. The results are shown in Tables 1 to 3.

[0572]

[0573] [Table 2-1]

[0574] Table 2-1 Composition of fluoroelastomer (a)

[0575]

[0576] [Table 2-2]

[0577] Table 2-2 Composition of crystalline fluorinated polymer (b)

[0578]

[0579] [Table 3]

[0580] Table 3

[0581]

Claims

1. A polymer blend comprising a fluorinated elastomer (a) and a crystalline fluorinated polymer (b), wherein: The fluorinated elastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units and nitrogen-containing crosslinking sites. The crystalline fluorinated polymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking sites, The melting point of the polymer blend is 310°C to 320°C, The content of the crystalline fluorinated polymer (b) in the polymer blend is from 4.0 to 15.0 mass % based on the total mass of the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

2. The polymer blend according to claim 1, wherein The Mooney viscosity of the polymer blend at 170° C. is 70-120.

3. The polymer blend according to claim 1 or 2, wherein The content of nitrogen-containing crosslinking sites in the polymer blend is from 0.5 to 3.0 mol %, based on 100 mol % of all monomer units constituting the fluorinated elastomer (a) and the crystalline fluorinated polymer (b).

4. The polymer blend according to any one of claims 1 to 3, wherein The content ratio of the tetrafluoroethylene unit to the fluoroalkyl vinyl ether unit in the polymer blend is 50 / 50 to 70 / 30 in terms of molar ratio, ie, tetrafluoroethylene unit / fluoroalkyl vinyl ether unit.

5. The polymer blend according to any one of claims 1 to 4, wherein The fluoroalkyl vinyl ether units in the fluorinated elastomer (a) are perfluoro(methyl vinyl ether) units.

6. The polymer blend according to any one of claims 1 to 5, wherein The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) contain monomer units having a nitrogen-containing crosslinkable group.

7. The polymer blend according to any one of claims 1 to 6, which is obtained by a manufacturing method comprising preparing an aqueous dispersion containing a fluorinated elastomer (a) and a crystalline fluorinated polymer (b) and precipitating the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion.

8. The polymer blend according to any one of claims 1 to 7, which is obtained by the following production method: (1-1) tetrafluoroethylene, fluoroalkyl vinyl ether and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a fluorinated elastomer (a); (1-2) tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b); (1-3) An aqueous dispersion containing a fluorinated elastomer (a) is mixed with an aqueous dispersion containing a crystalline fluorinated polymer (b) to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b); and (1-4) the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated to obtain the polymer blend.

9. The polymer blend according to any one of claims 1 to 8, wherein The content of the nitrogen-containing crosslinking site in the fluorinated elastomer (a) is from 0.5 to 3.0 mol %, based on 100 mol % of all monomer units constituting the fluorinated elastomer (a).

10. The polymer blend according to any one of claims 1 to 9, wherein The content of the nitrogen-containing crosslinking site in the crystalline fluorinated polymer (b) is from 0.5 to 3.0 mol %, based on 100 mol % of all monomer units constituting the crystalline fluorinated polymer (b).

11. The polymer blend according to any one of claims 1 to 7, which is obtained by the following production method: (2-1) Tetrafluoroethylene and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b); (2-2) in the presence of a crystalline fluorinated polymer (b) and an aqueous medium, tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b); (2-3) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated. 12 . A crosslinkable composition comprising the polymer blend according to claim 1 and at least one selected from the group consisting of an inorganic nitride, an organotin compound, an ammonia-generating compound, and a crosslinking agent.

13. An article obtained by crosslinking the crosslinkable composition according to claim 12.

14. The article of claim 13, wherein The article has a compression set of less than 50% when placed at 300°C for 70 hours. The article has a compression set of less than 50% after being placed at 200°C for 70 hours or at 70°C for 70 hours. The article has a hardness of 65 or greater as measured according to ASTM D2240.

15. A production method, which is a production method of the polymer blend according to any one of claims 1 to 10, wherein: (1-1) tetrafluoroethylene, fluoroalkyl vinyl ether and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a fluorinated elastomer (a); (1-2) tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b); (1-3) An aqueous dispersion containing a fluorinated elastomer (a) is mixed with an aqueous dispersion containing a crystalline fluorinated polymer (b) to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b); and (1-4) the fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated to obtain the polymer blend.

16. A production method, which is a production method of the polymer blend according to any one of claims 1 to 7 and 11, wherein: (2-1) Tetrafluoroethylene and a monomer having a nitrogen-containing crosslinking group are polymerized in the presence of an aqueous medium to prepare an aqueous dispersion containing a crystalline fluorinated polymer (b); (2-2) in the presence of a crystalline fluorinated polymer (b) and an aqueous medium, tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing the fluorinated elastomer (a) and the crystalline fluorinated polymer (b); (2-3) The fluorinated elastomer (a) and the crystalline fluorinated polymer (b) in the aqueous dispersion are precipitated to obtain the polymer blend.

17. The manufacturing method according to claim 16, wherein: (2-1) In a reaction vessel, an aqueous dispersion containing a crystalline fluorinated polymer (b) is prepared, (2-2) While continuing the polymerization reaction in the reaction vessel, fluoroalkyl vinyl ether is added to the reaction vessel to polymerize tetrafluoroethylene, fluoroalkyl vinyl ether, and the monomer having a nitrogen-containing crosslinking group.

18. An article, wherein The article has a compression set of less than 50% when placed at 300°C for 70 hours. The article has a compression set of less than 50% after being placed at 200°C for 70 hours or at 70°C for 70 hours. The article has a hardness of 65 or greater as measured according to ASTM D2240.

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