Polymer blend, crosslinkable composition, and article

Abstract

Provided is a polymer blend that contains a fluoroelastomer (a) and a crystalline fluoropolymer (b). The fluoroelastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking sites. The crystalline fluoropolymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking sites. The melting point of the polymer blend is 310°C–320°C. The crystalline fluoropolymer (b) content of the polymer blend is 4.0–15.0 mass% relative to the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b).

Description

Polymer blends, crosslinkable compositions and articles

[0001] The present disclosure relates to polymer blends, crosslinkable compositions and articles.

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

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

[0004] Special Publication No. 2009-500459

[0005] The present disclosure aims to provide a polymer blend containing a fluoroelastomer and a crystalline fluoropolymer, which has appropriate hardness, small compression set at high temperatures, and is capable of producing an article that is less likely to experience large compression set even after use under severe conditions.

[0006] According to the present disclosure, there is provided a polymer blend containing a fluoroelastomer (a) and a crystalline fluoropolymer (b), wherein the fluoroelastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking moieties, and the crystalline fluoropolymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking moieties, the melting point of the polymer blend is 310 to 320°C, and the content of the crystalline fluoropolymer (b) in the polymer blend is 4.0 to 15.0 mass% based on the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b).

[0007] According to the present disclosure, it is possible to provide a polymer blend containing a fluoroelastomer and a crystalline fluoropolymer, which has appropriate hardness, small compression set at high temperatures, and is capable of producing an article that is resistant to large compression set even after use under harsh conditions.

[0008] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0009] The polymer blends of the present disclosure contain a fluoroelastomer (a) and a crystalline fluoropolymer (b).

[0010] Patent Document 1 describes that by using the above-mentioned crosslinkable composite material, a composite material having a compression set of less than 50% can be obtained when tested at 150° C. However, it has now been found that such conventional composite materials have a problem in that even if the compression set is small before use, the compression set tends to increase when used under severe conditions.

[0011] On the other hand, the polymer blend of the present disclosure has the above-mentioned structure, so by using the polymer blend of the present disclosure, it is possible to obtain the article with moderate hardness and small compression set at high temperature, and also obtain the article that compression set is difficult to become large even after using under severe conditions.The reason for this is not clear, but it is presumed that this is because in polymer blend, both fluoroelastomer (a) and crystalline fluoropolymer (b) have nitrogen-containing crosslinking moiety, and also the melting point of polymer blend and the content of crystalline fluoropolymer (b) are appropriately adjusted, so that the nitrogen-containing crosslinking moiety that fluoroelastomer (a) has in polymer blend and the nitrogen-containing crosslinking moiety that crystalline fluoropolymer (b) has in polymer blend are co-crosslinked, and form the co-crosslinking structure in the article at a moderate ratio.

[0012] Fluoroelastomer (a) The polymer blends of the present disclosure contain a fluoroelastomer (a).

[0013] In this disclosure, a fluoroelastomer is an amorphous fluoropolymer. "Amorphous" means that the magnitude of the melting peak (ΔH) appearing 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 by crosslinking. Elastomeric properties refer to the ability of a polymer to be stretched and to retain its original length when the force required to stretch the polymer is no longer applied.

[0014] The fluoroelastomer may be a partially fluorinated elastomer or a perfluoroelastomer, but a perfluoroelastomer is preferred because it allows the production of an article with even smaller compression set at high temperatures and, further, an article in which the increase in compression set after use under severe conditions is further suppressed.

[0015] In the present disclosure, a partially fluorinated elastomer is a fluoropolymer that contains fluoromonomer units and has a perfluoromonomer unit content of less than 90 mol% relative to all monomer units, and that has a glass transition temperature of 20°C or lower and a melting peak (ΔH) magnitude of 4.5 J / g or lower.

[0016] In the present disclosure, a perfluoroelastomer is a fluoropolymer in which the content of perfluoromonomer units relative to all monomer units is 90 mol% or more, preferably 91 mol% or more, and which has a glass transition temperature of 20°C or less and a melting peak (ΔH) magnitude of 4.5 J / g or less, and further, a polymer in which the concentration of fluorine atoms contained in the fluoropolymer is 71 mass% or more, preferably 71.5 mass% or more. In the present disclosure, the concentration of fluorine atoms contained in the fluoropolymer is determined by calculation of the concentration (mass%) of fluorine atoms contained in the fluoropolymer from the type and content of each monomer constituting the fluoropolymer.

[0017] In the present disclosure, a perfluoromonomer is a monomer that does not contain a carbon atom-hydrogen atom bond in the molecule. The perfluoromonomer may be a monomer containing carbon atoms and fluorine atoms, or a monomer in which some of the fluorine atoms bonded to carbon atoms have been substituted with chlorine atoms, or may contain nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, boron atoms, or silicon atoms in addition to carbon atoms. The perfluoromonomer is preferably a monomer in which all hydrogen atoms have been substituted with fluorine atoms. The perfluoromonomer does not include monomers that provide crosslinking sites.

[0018] The monomer that provides a crosslinking site is a monomer (cure site monomer) having a crosslinkable group that provides a crosslinking site for forming a crosslink to the fluoropolymer.

[0019] In the present disclosure, the content of each monomer constituting the fluoroelastomer (a), the crystalline fluoropolymer (b), and the polymer blend can be calculated by appropriately combining NMR, FT-IR, elemental analysis, X-ray fluorescence analysis, and other known methods depending on the type of monomer.

[0020] The Mooney viscosity ML(1+20) at 170°C of the fluoroelastomer (a) is preferably 30 or more, more preferably 50 or more, even more preferably 60 or more, still more preferably 70 or more, and preferably 150 or less, more preferably 130 or less, even more preferably 120 or less, because this can impart appropriate hardness to an article, can provide an article with smaller compression set at high temperatures, and can provide an article in which the increase in compression set after use under severe conditions is further suppressed.

[0021] The Mooney viscosity of the fluoroelastomer (a) can be adjusted to fall within the above range by adjusting the composition and molecular weight of the monomers constituting the fluoroelastomer (a).

[0022] The Mooney viscosity can be measured at 170° C. in accordance with JIS K6300 using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES.

[0023] 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, because this allows an article to have appropriate hardness, a smaller compression set at high temperatures, and an article in which an increase in compression set after use under severe conditions is further suppressed.

[0024] The glass transition temperature can be determined as the temperature indicating the midpoint between two intersections of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve, obtained by heating 3 mg of a sample at 20°C / min using a differential scanning calorimeter (X-DSC7000, manufactured by Hitachi High-Tech Science Corporation).

[0025] The fluoroelastomer (a) included in the polymer blends of the present disclosure contains tetrafluoroethylene (TFE) units, fluoroalkyl vinyl ether (FAVE) units, and nitrogen-containing crosslinking sites.

[0026] The FAVE forming the FAVE unit is preferably a FAVE represented by the general formula (11): CF, since this allows for the production of an article with even smaller compression set at high temperatures and further allows for the production of an article in which the increase in compression set after use under severe conditions is further suppressed. ２ =CF-ORf １３ (wherein, Rf １３ represents a perfluoroalkyl group having 1 to 8 carbon atoms, a fluoromonomer represented by general formula (12): CF ２ = CFOCF ２ ORf １４ (wherein, Rf １４ is 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 and containing 1 to 3 oxygen atoms), and a fluoromonomer represented by the general formula (13): CF ２ = CFO (CF ２ CF (Y １５ ) O) ｍ (CF ２ ) ｎ F (wherein, Y １５ represents a fluorine atom or a trifluoromethyl group, m is an integer of 1 to 4, and n is an integer of 1 to 4.

[0027] As the FAVE, a fluoromonomer represented by the general formula (11) is preferred, and CF ２ =CF-OCF ３(perfluoro(methyl vinyl ether) (PMVE)), CF ２ =CF-OCF ２ CF ３ and C.F. ２ =CF-OCF ２ CF ２ CF ３ More preferably, at least one selected from the group consisting of CF ２ =CF-OCF ３ is more preferable.

[0028] The fluoroelastomer (a) included in the polymer blend of the present disclosure contains nitrogen-containing crosslinking moieties, which are moieties containing at least one nitrogen atom and through which the fluoroelastomer (a) forms crosslinks.

[0029] As the nitrogen-containing crosslinking moiety, a nitrogen-containing crosslinkable group is preferred. The nitrogen-containing crosslinkable group is not particularly limited as long as it contains at least one nitrogen atom and is a crosslinkable group that provides a fluoropolymer with a crosslinking moiety for forming a crosslink, and 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 crosslinkable group, a cyano group is preferred, since it can provide an article with a smaller compression set at high temperatures and further suppress the increase in compression set after use under harsh conditions.

[0030] When the fluoroelastomer (a) has a cyano group as a nitrogen-containing crosslinking moiety, the cyano group can crosslink by forming a triazine ring through cyclotrimerization, or by forming an imidazole ring using a tetramine compound as a crosslinking agent. By forming such crosslinks, the article can be provided with appropriate hardness and excellent compression set properties.

[0031] Nitrogen-containing crosslinking moieties can be introduced into fluoroelastomers, for example, by copolymerizing a monomer having a nitrogen-containing crosslinkable group during the production of the fluoroelastomer. Nitrogen-containing crosslinking moieties can also be introduced into fluoroelastomers, for example, by polymerizing a monomer 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(CF ２ ) ｎ CN (n is an integer of 1 to 15). Furthermore, nitrogen-containing crosslinking sites can be introduced into a fluoroelastomer, for example, by producing the fluoroelastomer and then reacting functional groups (such as -COF and -COOH) generated at the terminals of the fluoroelastomer with ammonia.

[0032] In one embodiment, the fluoroelastomer (a) contains monomer units having nitrogen-containing crosslinkable groups.

[0033] As the monomer having a nitrogen-containing crosslinkable group, a monomer having a cyano group is preferred. Examples of the monomer having a cyano group (-CN group) include a monomer represented by the formula: CY １ ２ =CY １ (CF ２ ) ｎ —CN (wherein Y １ are each independently a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8. ２ =CFCF ２ Rf ８ -CN (wherein, Rf ８ Ha-(OCF ２ ) ｎ - or - (OCF (CF ３ )) ｎ -, and n is an integer from 0 to 5) Formula: CF ２ =CFCF ２ (OCF (CF ３ )CF ２ ) ｍ (OCH ２ CF ２ CF ２ ) ｎ OCH ２ CF２ -CN (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) Formula: CF ２ =CFCF ２ (OCH ２ CF ２ CF ２ ) ｍ (OCF (CF ３ )CF ２ ) ｎ OCF (CF ３ )-CN (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ -CN (wherein m is an integer of 1 to 5) Formula: CF ２ = CFOCF ２ (CF (CF ３ ) OCF ２ ) ｎ CF(-CN)CF ３ (wherein n is an integer of 1 to 4) Formula: CF ２ = CFO (CF ２ ) ｎ OCF (CF ３ )-CN (wherein n is an integer of 2 to 5) Formula: CF ２ = CFO (CF ２ ) ｎ -(C ６ H ４ )-CN (wherein n is an integer of 1 to 6) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｎ OCF ２ CF (CF ３ )-CN (wherein n is an integer of 1 to 2) Formula: CH ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｎ CF (CF ３)-CN (wherein n is an integer of 0 to 5), Formula: CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 3) Formula: CH ２ =CFCF ２ OCF (CF ３ ) OCF (CF ３ )-CN Formula: CH ２ =CFCF ２ OCH ２ CF ２ -CN Formula: CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ CF ２ CF (CF ３ )-CN (wherein m is an integer of 0 or more) Formula: CF ２ = CFOCF(CF ３ )CF ２ O (CF ２ ) ｎ -CN (wherein n is an integer of 1 or more) Formula: CF ２ = CFOCF ２ OCF ２ CF (CF ３ ) OCF ２ -CN Formula: CF ２ = CFO (CF ２ ) ３ CN formula: CF ２ = CFO (CF ２ ) ５ These may be used alone or in any combination.

[0034] Among the above, the formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) is preferred, and CF ２ = CFOCF２ CF (CF ３ ) OCF ２ CF ２ CN is more preferred.

[0035] The content of the nitrogen-containing crosslinking moiety in the fluoroelastomer (a) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total amount of all monomer units constituting the fluoroelastomer (a) is 100 mol%.

[0036] The content of nitrogen-containing crosslinking moieties can be measured by infrared spectroscopy (IR).

[0037] The content of the nitrogen-containing crosslinkable group in the fluoroelastomer (a) is preferably 0.5 to 3.0 mol %, more preferably 2.0 mol % or less, and even more preferably 1.5 mol % or less, when the total amount of all monomer units constituting the fluoroelastomer (a) is taken as 100 mol %.

[0038] The content of nitrogen-containing crosslinkable groups can be measured by infrared spectroscopy (IR).

[0039] The content of cyano groups in the fluoroelastomer (a) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total amount of all monomer units constituting the fluoroelastomer (a) is 100 mol%.

[0040] The cyano group content can be measured by infrared spectroscopy (IR).

[0041] The content of the monomer unit having a nitrogen-containing crosslinkable group in the fluoroelastomer (a) is preferably 0.5 to 3.0 mol %, more preferably 2.0 mol % or less, and even more preferably 1.5 mol % or less, when the total amount of all the monomer units constituting the fluoroelastomer (a) is taken as 100 mol %.

[0042] The content of the monomer unit having a nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0043] The content of the monomer unit having a cyano group in the fluoroelastomer (a) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total amount of all the monomer units constituting the fluoroelastomer (a) is taken as 100 mol%.

[0044] The content of the monomer unit having a cyano group can be measured by infrared spectroscopy (IR).

[0045] As the fluoroelastomer (a), a copolymer containing TFE units, FAVE units and a monomer unit having a nitrogen-containing crosslinkable group is preferred, a copolymer containing TFE units, FAVE units and a monomer unit having a cyano group is more preferred, and a copolymer containing TFE units, PMVE units and a monomer unit having a cyano group is even more preferred.

[0046] 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, and even more preferably 98.5 mol% or more, when the total amount of all monomer units constituting the fluoroelastomer (a) is 100 mol%.

[0047] In a copolymer containing TFE units, FAVE units, and monomer units having a nitrogen-containing crosslinkable group, the content ratio (mol %) of TFE units / FAVE units / monomer units having a nitrogen-containing crosslinkable group 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 even more preferably 55.0 to 69.5 / 30.0 to 44.5 / 0.5 to 1.5.

[0048] Crystalline Fluoropolymer (b) The polymer blend of the present disclosure contains a crystalline fluoropolymer (b).

[0049] In this disclosure, a crystalline fluoropolymer is a partially crystalline fluorine-containing polymer, which is a fluoroplastic. A crystalline fluoropolymer has a melting point and is thermoplastic, but may be melt-processable or non-melt-processable. In this disclosure, melt-processable means that the polymer can be melted and processed using conventional processing equipment such as an extruder and an injection molding machine.

[0050] The melting point of the crystalline fluoropolymer (b) is 310 to 320° C. The melting point is preferably 311° C. or higher, more preferably 312° C. or higher, and even more preferably 313° C. or higher, and is preferably 319° C. or lower, and more preferably 318° C. or lower.

[0051] If the melting point of the crystalline fluoropolymer (b) 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 crystalline fluoropolymer (b) is too high, it may be difficult to obtain an article with a small compression set even after use under severe conditions.

[0052] The melting point of crystalline fluoropolymer (b) can be adjusted within the above-mentioned range, for example, by adjusting the composition of the monomer that constitutes crystalline fluoropolymer (b).When the content of tetrafluoroethylene unit is increased, the melting point of crystalline fluoropolymer (b) tends to be higher, and when the content of tetrafluoroethylene unit is reduced, the melting point of crystalline fluoropolymer (b) tends to be lower.

[0053] The melting point of the crystalline fluoropolymer (b) can be measured using a TG / DTA (thermogravimetric / differential thermal analyzer) by precisely weighing out about 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 then heating the aluminum pan in an air atmosphere over a temperature range of 25° C. to 600° C. at a rate of 10° C. / min to obtain a DTA curve, and the temperature corresponding to the peak in the obtained DTA curve is identified as the melting point of the polymer blend.

[0054] The melting point of the crystalline fluoropolymer (b) can be considered to be the same as the melting point of the polymer blend when the only substance that shows a melting point in the polymer blend is the crystalline fluoropolymer (b). Therefore, by measuring the melting point of the polymer blend, the melting point of the crystalline fluoropolymer (b) can also be determined.

[0055] The crystalline fluoropolymer (b) included in the polymer blend of the present disclosure contains tetrafluoroethylene (TFE) units and nitrogen-containing crosslinking sites.

[0056] The crystalline fluoropolymer (b) may contain other monomer units formed by other monomers copolymerizable with TFE (excluding TFE units and monomer units having a nitrogen-containing crosslinkable group).

[0057] The other monomers (excluding TFE and monomers having a nitrogen-containing crosslinkable group) are not particularly limited as long as they are copolymerizable 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; perfluoroalkylethylene:ethylene; and the like.

[0058] The content of other monomer units in the crystalline fluoropolymer (b) is preferably 0 to 0.10 mol%, more preferably 0.06 mol% or less, even more preferably 0.02 mol% or less, based on the total monomer units constituting the crystalline fluoropolymer (b), and may be 0 mol%.

[0059] The crystalline fluoropolymer (b) contained in the polymer blend of the present disclosure contains a nitrogen-containing crosslinking moiety. The nitrogen-containing crosslinking moiety is a moiety containing at least one nitrogen atom, and is a moiety for forming crosslinks in the crystalline fluoropolymer (b).

[0060] As the nitrogen-containing crosslinking moiety, a nitrogen-containing crosslinkable group is preferred. The nitrogen-containing crosslinkable group is not particularly limited as long as it contains at least one nitrogen atom and is a crosslinkable group that provides a fluoropolymer with a crosslinking moiety for forming a crosslink, and 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 crosslinkable group, a cyano group is preferred, since it can provide an article with a smaller compression set at high temperatures and further suppress the increase in compression set after use under harsh conditions.

[0061] When the crystalline fluoropolymer (b) has a cyano group as a nitrogen-containing crosslinking site, the cyano group can form a triazine ring by cyclotrimerization, or form an imidazole ring by using a tetramine compound as a crosslinking agent. By forming such crosslinks, the article can be given appropriate hardness and excellent compression set properties.

[0062] Nitrogen-containing crosslinking moieties can be introduced into a crystalline fluoropolymer, for example, by copolymerizing a monomer having a nitrogen-containing crosslinkable group when producing the crystalline fluoropolymer. Nitrogen-containing crosslinking moieties can also be introduced into a crystalline fluoropolymer, for example, by polymerizing a monomer in the presence of a nitrogen-containing chain transfer agent when producing the crystalline fluoropolymer. Examples of nitrogen-containing chain transfer agents include I(CF ２ ) ｎ CN (n is an integer of 1 to 15). Furthermore, the nitrogen-containing crosslinking site can be introduced into the crystalline fluoropolymer by, for example, producing the crystalline fluoropolymer and then reacting a functional group (for example, —COF, —COOH, etc.) generated at the end of the crystalline fluoropolymer with ammonia.

[0063] In one embodiment, the crystalline fluoropolymer (b) contains a monomer unit having a nitrogen-containing crosslinkable group.

[0064] As the monomer having a nitrogen-containing crosslinkable group, a monomer having a cyano group is preferred. Examples of the monomer having a cyano group (-CN group) include a monomer represented by the formula: CY １ ２ =CY １ (CF ２ ) ｎ —CN (wherein Y １ are each independently a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8. ２ =CFCF ２ Rf ８ -CN (wherein, Rf ８ Ha-(OCF ２ ) ｎ - or - (OCF (CF ３ )) ｎ -, and n is an integer from 0 to 5) Formula: CF ２ =CFCF ２ (OCF (CF ３ )CF ２ ) ｍ (OCH ２ CF ２ CF ２ ) ｎ OCH ２ CF ２ -CN (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) Formula: CF ２ =CFCF ２ (OCH ２ CF ２ CF ２ ) ｍ (OCF (CF ３ )CF ２ ) ｎ OCF (CF ３ )-CN (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ -CN (wherein m is an integer of 1 to 5) Formula: CF２ = CFOCF ２ (CF (CF ３ ) OCF ２ ) ｎ CF(-CN)CF ３ (wherein n is an integer of 1 to 4) Formula: CF ２ = CFO (CF ２ ) ｎ OCF (CF ３ )-CN (wherein n is an integer of 2 to 5) Formula: CF ２ = CFO (CF ２ ) ｎ -(C ６ H ４ )-CN (wherein n is an integer of 1 to 6) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｎ OCF ２ CF (CF ３ )-CN (wherein n is an integer of 1 to 2) Formula: CH ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｎ CF (CF ３ )-CN (wherein n is an integer of 0 to 5), Formula: CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 3) Formula: CH ２ =CFCF ２ OCF (CF ３ ) OCF (CF ３ )-CN Formula: CH ２ =CFCF ２ OCH ２ CF ２ -CN Formula: CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ CF ２ CF (CF ３ )-CN (wherein m is an integer of 0 or more) Formula: CF ２ = CFOCF(CF３ )CF ２ O (CF ２ ) ｎ -CN (wherein n is an integer of 1 or more) Formula: CF ２ = CFOCF ２ OCF ２ CF (CF ３ ) OCF ２ -CN Formula: CF ２ = CFO (CF ２ ) ３ CN formula: CF ２ = CFO (CF ２ ) ５ These may be used alone or in any combination.

[0065] Among the above, the formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) is preferred, and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN is more preferred.

[0066] The content of the nitrogen-containing crosslinking moiety in the crystalline fluoropolymer (b) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the crystalline fluoropolymer (b) is 100 mol%.

[0067] The content of nitrogen-containing crosslinking moieties can be measured by infrared spectroscopy (IR).

[0068] The content of the nitrogen-containing crosslinkable group in the crystalline fluoropolymer (b) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the crystalline fluoropolymer (b) is 100 mol%.

[0069] The content of nitrogen-containing crosslinkable groups can be measured by infrared spectroscopy (IR).

[0070] The content of cyano groups in the crystalline fluoropolymer (b) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the crystalline fluoropolymer (b) is 100 mol%.

[0071] The cyano group content can be measured by infrared spectroscopy (IR).

[0072] The content of the monomer unit having a nitrogen-containing crosslinkable group in the crystalline fluoropolymer (b) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total amount of all the monomer units constituting the crystalline fluoropolymer (b) is taken as 100 mol%.

[0073] The content of the monomer unit having a nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0074] The content of the monomer unit having a cyano group in the crystalline fluoropolymer (b) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total amount of all the monomer units constituting the crystalline fluoropolymer (b) is 100 mol%.

[0075] The content of the monomer unit having a cyano group can be measured by infrared spectroscopy (IR).

[0076] As the crystalline fluoropolymer (b), a copolymer containing TFE units and monomer units having a nitrogen-containing crosslinkable group is preferred, and a copolymer containing TFE units and monomer units having a cyano group is more preferred.

[0077] The content of TFE unit in crystalline fluoropolymer (b) is preferably 97.0 to 99.5 mol%, more preferably 98.0 mol% or more, and even more preferably 98.5 mol% or more, when the total monomer unit that constitutes crystalline fluoropolymer (b) is 100 mol%.

[0078] (Polymer Blend) The polymer blend of the present disclosure has a melting point of 310 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 is preferably 319° C. or lower, and more preferably 318° C. or lower.

[0079] If the melting point of the polymer blend is too low, it may be difficult to obtain an article with low compression set at high temperatures. If the melting point of the polymer blend is too high, it may be difficult to obtain an article that is unlikely to experience large compression set even after use under harsh conditions. If a polymer blend is used that does not show a clear melting point, it may be difficult to obtain an article with appropriate hardness.

[0080] The melting point of the polymer blend can be adjusted to fall within the above range, for example, by adjusting the melting point of the crystalline fluoropolymer (b) and the content of the crystalline fluoropolymer (b).

[0081] The melting point of the polymer blend can be measured using a TG / DTA (thermogravimetric / differential thermal analyzer) by precisely weighing out about 10 mg of the polymer blend that has not been heated to a temperature of 300° C. or higher, placing it in a dedicated aluminum pan, and then heating the aluminum pan in an air atmosphere from 25° C. to 600° C. at a rate of 10° C. / min to obtain a DTA curve, and the temperature corresponding to the peak in the obtained DTA curve is identified as the melting point of the polymer blend.

[0082] The Mooney viscosity ML(1+20) at 170°C of the polymer blend is preferably 30 to 150, more preferably 50 or more, even more preferably 60 or more, still more preferably 70 or more, and more preferably 130 or less, and even more preferably 120 or less, because this allows an article to have appropriate hardness, an article with even smaller compression set at high temperatures to be obtained, and an article in which an increase in compression set after use under severe conditions is further suppressed.

[0083] The Mooney viscosity of the polymer blend can be adjusted to fall within the above range, for example, by adjusting the Mooney viscosity of the fluoroelastomer (a) and the content of the fluoroelastomer (a).

[0084] The Mooney viscosity can be measured at 170° C. in accordance with JIS K6300 using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES.

[0085] The glass transition temperature of the polymer blend 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, because this allows an article to have appropriate hardness, has smaller compression set at high temperatures, and is further able to suppress an increase in compression set after use under severe conditions.

[0086] The glass transition temperature can be determined as the temperature indicating the midpoint between two intersections of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve, obtained by heating 3 mg of a sample at 20°C / min using a differential scanning calorimeter (X-DSC7000, manufactured by Hitachi High-Tech Science Corporation).

[0087] The polymer blend of the present disclosure contains a fluoroelastomer (a) and a crystalline fluoropolymer (b). The content of the crystalline fluoropolymer (b) in the polymer blend is 4.0 to 15.0% by mass, based on the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b).

[0088] The content of the crystalline fluoropolymer (b) in the polymer blend is preferably 4.2% by mass or more, more preferably 4.4% by mass or more, even more preferably 4.6% by mass or more, and preferably 14.0% by mass or less, more preferably 13.0% by mass or less, even more preferably 12.0% by mass or less.

[0089] If the content of crystalline fluoropolymer (b) in the polymer blend is too low, it is difficult to give the article a suitable hardness.If the content of crystalline fluoropolymer (b) in the polymer blend is too high, it is difficult to obtain an article with a low compression set at high temperature, or it is difficult to obtain an article with a low compression set even after being used under severe conditions.

[0090] The content of crystalline fluoropolymer (b) in a polymer blend can be measured by precisely weighing out about 10 mg of a polymer blend that has not been heated to temperatures above 300°C, placing it in a dedicated aluminum pan, and using a TG / DTA (differential thermal analysis) apparatus. The aluminum pan is heated in an air atmosphere over a temperature range from 25°C to 600°C at a rate of 10°C / min to obtain a TG curve, and the weight loss rate is calculated from the obtained TG curve to determine the content. Since the fluoroelastomer (a) in a polymer blend usually undergoes thermal decomposition at a lower temperature than the crystalline fluoropolymer (b), the weight loss rates due to the thermal decomposition of the fluoroelastomer (a) and the crystalline fluoropolymer (b) can be determined separately from the TG curve.

[0091] Furthermore, when the production conditions of the polymer blend can be grasped, the content of the crystalline fluoropolymer (b) in the polymer blend can also be calculated from the amounts of the raw materials used.

[0092] The polymer blend of the present disclosure contains a fluoroelastomer (a) and a crystalline fluoropolymer (b). Further, the fluoroelastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking sites, and the crystalline fluoropolymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking sites.

[0093] The FAVE forming the FAVE unit is preferably a FAVE represented by the general formula (11): CF, since this allows for the production of an article with even smaller compression set at high temperatures and further allows for the production of an article in which the increase in compression set after use under severe conditions is further suppressed. ２ =CF-ORf １３ (wherein, Rf １３ represents a perfluoroalkyl group having 1 to 8 carbon atoms, a fluoromonomer represented by general formula (12): CF ２ = CFOCF ２ ORf １４ (wherein, Rf １４ is 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 and containing 1 to 3 oxygen atoms), and a fluoromonomer represented by the general formula (13): CF ２ = CFO (CF ２ CF (Y １５ ) O) ｍ (CF ２ ) ｎ F (wherein, Y １５ represents a fluorine atom or a trifluoromethyl group, m is an integer of 1 to 4, and n is an integer of 1 to 4.

[0094] As the FAVE, a fluoromonomer represented by the general formula (11) is preferred, and CF ２ =CF-OCF ３ (perfluoro(methyl vinyl ether) (PMVE)), CF ２ =CF-OCF ２ CF ３ and C.F. ２ =CF-OCF ２ CF ２ CF ３ More preferably, at least one selected from the group consisting of CF ２ =CF-OCF ３ is more preferable.

[0095] The content ratio of tetrafluoroethylene units to fluoroalkyl vinyl ether units in the polymer blend is preferably 50 / 50 to 70 / 30, more preferably 51 / 49 or more, even more preferably 52 / 48 or more, still more preferably 53 / 47 or more, more preferably 69 / 31 or less, and even more preferably 68 / 32 or less, in terms of molar ratio (tetrafluoroethylene units / fluoroalkyl vinyl ether units). Furthermore, the content ratio of tetrafluoroethylene units to fluoroalkyl vinyl ether units in the polymer blend may be 54 / 46 or more, and may be 65 / 35 or less, or 60 / 40 or less, in terms of molar ratio (tetrafluoroethylene units / fluoroalkyl vinyl ether units).

[0096] If the molar ratio (tetrafluoroethylene unit / fluoroalkyl vinyl ether unit) is too high, it may be difficult to impart an appropriate hardness to the article.If the molar ratio is too low, it may be difficult to obtain an article with too high hardness, an article with small compression set at high temperatures, or an article with little compression set even after use under severe conditions.

[0097] The fluoroelastomer (a) and the crystalline fluoropolymer (b) contain nitrogen-containing crosslinking sites, which are sites containing at least one nitrogen atom and are used to form crosslinks between the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the polymer blend.

[0098] As the nitrogen-containing crosslinking moiety, a nitrogen-containing crosslinkable group is preferred. The nitrogen-containing crosslinkable group is not particularly limited as long as it contains at least one nitrogen atom and is a crosslinkable group that provides a fluoropolymer with a crosslinking moiety for forming a crosslink, and 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 crosslinkable group, a cyano group is preferred, since it can provide an article with a smaller compression set at high temperatures and further suppress the increase in compression set after use under harsh conditions.

[0099] When the fluoroelastomer (a) and the crystalline fluoropolymer (b) have a cyano group as a nitrogen-containing crosslinking site, the cyano group can form a triazine ring by cyclotrimerization, or form an imidazole ring by using a tetramine compound as a crosslinking agent.By forming such crosslinks, the article can be given appropriate hardness and excellent compression set properties.

[0100] Nitrogen-containing crosslinking moieties can be introduced into crystalline fluoropolymers, for example, by copolymerizing a monomer having a nitrogen-containing crosslinkable group when producing the fluoroelastomers and crystalline fluoropolymers. Nitrogen-containing crosslinking moieties can also be introduced into fluoroelastomers and crystalline fluoropolymers, for example, by polymerizing a monomer in the presence of a nitrogen-containing chain transfer agent when producing the fluoroelastomers and crystalline fluoropolymers. Examples of nitrogen-containing chain transfer agents include I(CF ２ ) ｎCN (n is an integer of 1 to 15). Furthermore, nitrogen-containing crosslinking sites can be introduced into fluoroelastomers and crystalline fluoropolymers, for example, by producing the fluoroelastomers and crystalline fluoropolymers and then reacting functional groups (for example, -COF, -COOH, etc.) generated at the ends of the fluoroelastomers and crystalline fluoropolymers with ammonia.

[0101] In one embodiment, the fluoroelastomer (a) and the crystalline fluoropolymer (b) contain monomer units having nitrogen-containing crosslinkable groups.

[0102] As the monomer having a nitrogen-containing crosslinkable group, a monomer having a cyano group is preferred. Examples of the monomer having a cyano group (-CN group) include a monomer represented by the formula: CY １ ２ =CY １ (CF ２ ) ｎ —CN (wherein Y １ are each independently a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8. ２ =CFCF ２ Rf ８ -CN (wherein, Rf ８ Ha-(OCF ２ ) ｎ - or - (OCF (CF ３ )) ｎ -, and n is an integer from 0 to 5) Formula: CF ２ =CFCF ２ (OCF (CF ３ )CF ２ ) ｍ (OCH ２ CF ２ CF ２ ) ｎ OCH ２ CF ２ -CN (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) Formula: CF ２ =CFCF ２ (OCH ２ CF ２ CF ２ ) ｍ (OCF (CF ３)CF ２ ) ｎ OCF (CF ３ )-CN (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ -CN (wherein m is an integer of 1 to 5) Formula: CF ２ = CFOCF ２ (CF (CF ３ ) OCF ２ ) ｎ CF(-CN)CF ３ (wherein n is an integer of 1 to 4) Formula: CF ２ = CFO (CF ２ ) ｎ OCF (CF ３ )-CN (wherein n is an integer of 2 to 5) Formula: CF ２ = CFO (CF ２ ) ｎ -(C ６ H ４ )-CN (wherein n is an integer of 1 to 6) Formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｎ OCF ２ CF (CF ３ )-CN (wherein n is an integer of 1 to 2) Formula: CH ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｎ CF (CF ３ )-CN (wherein n is an integer of 0 to 5), Formula: CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ-CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 3) Formula: CH ２ =CFCF ２ OCF (CF ３ ) OCF (CF ３ )-CN Formula: CH ２ =CFCF ２ OCH ２ CF ２ -CN Formula: CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ CF ２ CF (CF ３ )-CN (wherein m is an integer of 0 or more) Formula: CF ２ = CFOCF(CF ３ )CF ２ O (CF ２ ) ｎ -CN (wherein n is an integer of 1 or more) Formula: CF ２ = CFOCF ２ OCF ２ CF (CF ３ ) OCF ２ -CN Formula: CF ２ = CFO (CF ２ ) ３ CN formula: CF ２ = CFO (CF ２ ) ５ These may be used alone or in any combination.

[0103] Among the above, the formula: CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) is preferred, and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN is more preferred.

[0104] The content of nitrogen-containing crosslinking moieties in the polymer blend is 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b) are taken as 100 mol%.

[0105] The content of nitrogen-containing crosslinking moieties can be measured by infrared spectroscopy (IR).

[0106] The content of the nitrogen-containing crosslinkable group in the polymer blend is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b) are taken as 100 mol%.

[0107] The content of nitrogen-containing crosslinkable groups can be measured by infrared spectroscopy (IR).

[0108] The content of cyano groups in the polymer blend is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b) are taken as 100 mol%.

[0109] The cyano group content can be measured by infrared spectroscopy (IR).

[0110] The content of the monomer unit having a nitrogen-containing crosslinkable group in the polymer blend is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total amount of all monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b) is taken as 100 mol%.

[0111] The content of the monomer unit having a nitrogen-containing crosslinkable group can be measured by infrared spectroscopy (IR).

[0112] The content of the monomer unit having a cyano group in the polymer blend is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b) are taken as 100 mol%.

[0113] The content of the monomer unit having a cyano group can be measured by infrared spectroscopy (IR).

[0114] The content of TFE unit and FAVE unit in polymer blend is preferably 97.0 to 99.5 mol%, more preferably 98.0 mol% or more, and even more preferably 98.5 mol% or more, when the total monomer units constituting fluoroelastomer (a) and crystalline fluoropolymer (b) are 100 mol%.

[0115] (Method for producing polymer blend) The polymer blend of the present disclosure can be produced by a production method in which the fluoroelastomer (a) and the crystalline fluoropolymer (b) are mixed, or by a production method in which the fluoroelastomer (a) and the crystalline fluoropolymer (b) are produced by two-stage polymerization.

[0116] The polymer blend of the present disclosure is preferably produced by preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b), and coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion.

[0117] Even when using the polymer blend obtained by the manufacturing method of mixing the solid matter of fluoroelastomer (a) and the solid matter of crystalline fluoropolymer (b), it is possible to obtain the article with moderate hardness, low compression set at high temperature, and even after using under severe conditions, the compression set is not easily increased.However, it has now become clear that the polymer blend obtained by the manufacturing method of coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in aqueous dispersion has a lower compression set at high temperature than the polymer blend obtained by the manufacturing method of mixing the solid matter of fluoroelastomer (a) and the solid matter of crystalline fluoropolymer (b), and the article has a lower compression set at high temperature, and even after using under severe conditions, the increase of the compression set is more suppressed.The reason for this is not clear, but it is presumed that the reaction of the nitrogen-containing crosslinking moiety of fluoroelastomer (a) and the nitrogen-containing crosslinking moiety of crystalline fluoropolymer (b) to form a co-crosslinked structure proceeds smoothly.

[0118] The method for preparing the aqueous dispersion that contains fluoroelastomer (a) and crystalline fluoropolymer (b) can be enumerated as the method that contains fluoroelastomer (a) and the aqueous dispersion that contains crystalline fluoropolymer (b) mix, the method that contains fluoroelastomer (a) powder and the aqueous dispersion that contains crystalline fluoropolymer (b) mix, the method that contains fluoroelastomer (a) and the aqueous dispersion that contains crystalline fluoropolymer (b) mix, etc.Among them, the method that contains fluoroelastomer (a) and the aqueous dispersion that contains crystalline fluoropolymer (b) mix is ​​preferred.

[0119] The method of coagulating the fluoroelastomer (a) and crystalline fluoropolymer (b) in aqueous dispersion can be by mixing aqueous dispersion with coagulant or by freezing aqueous dispersion.As coagulant, known coagulant such as acid can be used, for example, aluminum salt, calcium salt or magnesium salt, organic coagulant such as ammonium acetate, ammonium carbonate, inorganic acid coagulant such as hydrochloric acid, nitric acid, hydrofluoric acid, sulfuric acid, trifluoroacetic acid, etc.

[0120] The coagulate obtained by coagulation may be washed with water to remove small amounts of impurities present in the coagulate, such as buffer solutions and salts, and then the washed coagulate may be dried in a hot air oven, vacuum dryer, or the like to prepare a polymer blend.

[0121] The form of the polymer blend obtained after coagulation is not particularly limited, but may be gum, crumb, powder, pellet, etc., and is preferably gum or crumb. Gum is a small granular mass consisting of the polymer blend, and crumb is an amorphous mass formed when the fluoroelastomer (a) in the polymer blend cannot maintain the small granular shape as a gum at room temperature and fuses with each other.

[0122] Among the methods for producing polymer blends of the present disclosure, preferred production methods for mixing fluoroelastomer (a) and crystalline fluoropolymer (b) include: (1-1) preparing an aqueous dispersion containing fluoroelastomer (a) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-2) preparing an aqueous dispersion containing crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-3) preparing an aqueous dispersion containing fluoroelastomer (a) and crystalline fluoropolymer (b) by mixing the aqueous dispersion containing fluoroelastomer (a) and the aqueous dispersion containing crystalline fluoropolymer (b); and (1-4) obtaining a polymer blend by coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion.

[0123] The aqueous dispersion containing the fluoroelastomer (a) and the aqueous dispersion containing the crystalline fluoropolymer (b) can be prepared by known polymerization methods.

[0124] Among the methods for producing polymer blends of the present disclosure, the method for producing fluoroelastomer (a) and crystalline fluoropolymer (b) by two-stage polymerization is preferably the following production method: (2-1) in the presence of an aqueous medium, polymerize tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group to prepare an aqueous dispersion containing crystalline fluoropolymer (b); (2-2) in the presence of crystalline fluoropolymer (b) and an aqueous medium, polymerize tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group to prepare an aqueous dispersion containing fluoroelastomer (a) and crystalline fluoropolymer (b); and (2-3) coagulate the fluoroelastomer (a) and crystalline fluoropolymer (b) in the aqueous dispersion.

[0125] In the above production method, the polymerization in step (2-1) and the polymerization in step (2-2) can 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 terminating the polymerization in step (2-1), or the polymerization in step (2-2) may be started without terminating the polymerization in step (2-1).

[0126] In one embodiment of the above-mentioned production method, (2-1) an aqueous dispersion containing the crystalline fluoropolymer (b) is prepared in a reaction vessel, and then (2-2) while continuing the polymerization reaction in the reaction vessel, a fluoroalkyl vinyl ether is introduced into the reaction vessel to polymerize tetrafluoroethylene, the fluoroalkyl vinyl ether, and the monomer having a nitrogen-containing crosslinkable group.

[0127] In this way, by producing a polymer blend by successive polymerization reactions, it is possible to produce a polymer blend that can impart appropriate hardness to an article, can produce an article with even smaller compression set at high temperatures, and can further suppress the increase in compression set after use under severe conditions.

[0128] 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.

[0129] The polymerization initiator may be an oil-soluble radical polymerization initiator or a water-soluble radical initiator.

[0130] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and the like. In addition, di(ω-hydroperfluorohexanoyl) peroxide, di(ω di(ω-hydro-dodecafluoroheptanoyl) peroxide, di(ω-hydro-tetradecafluorooctanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluparyl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di(perfluorooctanoyl) peroxide, di(perfluorononanoyl) peroxide -oxide, di(ω-chloro-hexafluorobutyryl)peroxide, di(ω-chloro-decafluorohexanoyl)peroxide, di(ω-chloro-tetradecafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluoro Representative examples include di[perfluoro(or fluorochloro)acyl]peroxides such as butyryl peroxide, di(dichloropentafluorobutanoyl)peroxide, di(trichlorooctafluorohexanoyl)peroxide, di(tetrachloroundecafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, and di(undecachlorodotriacontafluorodocosanoyl)peroxide.

[0131] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, or sodium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, or percarbonate, t-butyl permaleate, or t-butyl hydroperoxide. A reducing agent such as a sulfite may also be contained, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0132] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously at the beginning of polymerization in an amount (for example, several ppm relative to water concentration) that does not significantly decrease the polymerization rate. The upper limit is within the range in which the heat of polymerization reaction can be removed from the equipment.

[0133] As the surfactant, a nonionic surfactant, an anionic surfactant, a cationic surfactant, etc. can be used, and fluorine-based surfactants such as those used in WO 2000 / 029479, U.S. Patent Application Publication No. 2007 / 0015865, and JP 2014-540475 A can also be used. The amount added (relative to the solvent) is preferably 10 ppm by mass to 20% by mass, more preferably 10 ppm by mass to 10% by mass, even more preferably 10 ppm by mass to 7% by mass, and particularly preferably 50 ppm by mass to 5% by mass.

[0134] Furthermore, a reactive emulsifier may be used as the surfactant. The reactive emulsifier is not particularly limited as long as it is a compound having at least one unsaturated bond and at least one hydrophilic group. For example, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ , C.H. ２ =CFCF ２ CF (CF ３ ) OCF ２ CF ２ COONH ４ , C.F. ２ = CFOCF ２ CF (CF ３ ) OCF (CF ３ ) COONH ４The amount added (relative to the solvent) is preferably 10 to 5000 ppm by mass, and more preferably 50 to 5000 ppm by mass.

[0135] Alternatively, instead of a surfactant, a polymer of a compound having one or more unsaturated bonds and one or more hydrophilic groups may be used. Examples of such a polymer include CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ , C.H. ２ =CFCF ２ CF (CF ３ ) OCF ２ CF ２ COONH ４ , C.F. ２ = CFOCF ２ CF (CF ３ ) OCF (CF ３ ) COONH ４ The amount added (relative to the solvent) is preferably 10 ppm by mass to 10% by mass, more preferably 50 ppm by mass to 5% by mass, and even more preferably 50 ppm by mass to 2% by mass.

[0136] The aqueous medium is preferably a medium that does not have chain transfer properties, and 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.

[0137] The polymerization may also be carried out in the presence of a chain transfer agent. As the chain transfer agent, in addition to the above-mentioned nitrogen-containing chain transfer agents, an iodine compound or a bromine compound can also be used. As a polymerization method using an iodine compound or a bromine compound, for example, a method of carrying out emulsion polymerization in an aqueous medium under pressure in the presence of an iodine compound or a bromine compound in a substantially oxygen-free state (iodine transfer polymerization method) can be mentioned. Representative examples of the iodine compound or bromine compound to be used include, for example, compounds represented by the general formula: R ２１ I ｘ Br ｙ (wherein x and y are each an integer of 0 to 2 and satisfy 1≦x+y≦2; R２１ is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom). By using an iodine compound or a bromine compound, iodine atoms or bromine atoms are introduced into the polymer and function as crosslinking points.

[0138] Examples of iodine compounds and bromine compounds include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF ２ Br ２ , BrCF ２ CF ２ Br, CF ３ CFBrCF ２ Br, CFClBr ２ , BrCF ２ CFClBr, CFBrClCFClBr, BrCF ２ CF ２ CF ２ Br, BrCF ２ CFBrOCF ３ , 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl)- and (2-bromoethyl)-substituted benzenes. These compounds may be used alone or in combination with one another.

[0139] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, and the like.

[0140] The polymerization temperature, polymerization pressure, and polymerization time vary depending on the type of solvent and polymerization initiator, but may be -15 to 150°C, atmospheric pressure to 12 MPa, and 1 to 24 hours. When an oil-soluble radical polymerization initiator is used as the polymerization initiator, the polymerization temperature is preferably 30 to 95°C. When a water-soluble radical polymerization initiator is used as the polymerization initiator, the polymerization temperature is preferably 0 to 100°C, and more preferably 10 to 95°C.

[0141] (Crosslinkable Composition) A crosslinkable composition can be prepared by mixing the above-described polymer blend with at least one selected from the group consisting of inorganic nitrides, organic tin compounds, compounds that generate ammonia, and crosslinking agents. An article (crosslinked product) can be obtained by crosslinking the crosslinkable composition containing the above-described polymer blend and at least one selected from the group consisting of inorganic nitrides, organic tin compounds, compounds that generate ammonia, and crosslinking agents.

[0142] The inorganic nitride is not particularly limited, but silicon nitride (Si ３ N ４ ), lithium nitride, titanium nitride, aluminum nitride, boron nitride, vanadium nitride, zirconium nitride, etc. Among these, silicon nitride is preferred because it can be supplied as nano-sized fine particles.

[0143] Examples of the organotin compounds include tetraphenyltin and triphenyltin.

[0144] The compound that generates ammonia is preferably a compound that generates ammonia at 40 to 330°C.

[0145] The ammonia-generating compound is preferably urea or its derivatives, 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. The ammonia-generating compound may also be one that reacts with a trace amount of water to generate ammonia.

[0146] Examples of urea derivatives include biurea, thiourea, urea hydrochloride, and biuret.

[0147] Examples of organic ammonium salts include ammonium salts of non-fluorine-containing carboxylic acids or sulfonic acids such as ammonium benzoate, ammonium adipate, and ammonium phthalate.

[0148] Examples of inorganic ammonium salts include compounds described in JP-A-9-111081, such as ammonium sulfate, ammonium carbonate, ammonium nitrate, and ammonium phosphate.

[0149] Further, examples of the ammonia-generating compound include acetaldehyde ammonia, hexamethylenetetramine, formamidine, formamidine hydrochloride, formamidine acetate, t-butyl carbamate, benzyl carbamate, and phthalamide.

[0150] Examples of the crosslinking agent include crosslinking agents used in peroxide crosslinking, polyol crosslinking, polyamine crosslinking, triazine crosslinking, oxazole crosslinking, imidazole crosslinking, and thiazole crosslinking.

[0151] The crosslinking agent used in peroxide crosslinking may be any organic peroxide that can easily generate peroxy radicals in the presence of heat or a redox system, and specific examples thereof include 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butyl peroxide (Perbutyl D), t-butylcumyl peroxide (Perbutyl C), dicumyl peroxide (Percumyl D, Percumyl D-40, Percumyl D-40MB(T)), α,α- Bis(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (Perhexa 25B, Perhexa 25B-40), 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3 (Perhexyne 25B, Perhexyne 25B-40), benzoyl peroxide, t-butylperoxybenzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (Perhexa 25Z), t-butylperoxymaleic acid (t-butyl MA), t-butyl Chilperoxy isopropyl carbonate (Perbutyl I-75), methyl ethyl ketone peroxide (Permec D (DR), Permec H (HR, HY), Permec N (NR, NY), Permec S (SR), Permec F (FR), Permec G (GR, GY)), cyclohexanone peroxide (Perhexa H), acetylacetone peroxide (Percure AH, AL), 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane (Perhexa TMH), 1,1-di(t-hexyl peroxy)cyclohexane (Perhexa HC), 1,1-di(t-butylperoxy)-2-methylcyclohexane (Perhexa MC), 1,1-di(t-butylperoxy)cyclohexane (Perhexa C-80(S), Perhexa C-75(EB), Perhexa C(C), Perhexa C-40, Perhexa C-40MB(S)), 2,2-di(t-butylperoxy)butane (Perhexa 22), 4,4-di-(t-butylperoxy)butylpentanoate (Perhexa V, Perhexa V-40(F)), 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane (Pertetra A), p-menthane hydroperoxide (Permenta H), diisopropylbenzene hydroperoxide (Percumyl P), 1,1,3,3-tetramethylbutyl hydroperoxide (Perocta H), cumene hydroperoxide (Percumyl H-80), t-butyl hydroperoxide (Perbutyl H-69), di(2-t-butylperoxyisopropyl Benzene (Perbutyl P, Perbutyl P-40, Peroximon F-40, Perbutyl P-40MB(K)), di-t-hexyl peroxide (Perhexyl D), diisobutyryl peroxide (Perloyl IB), di(3,5,5-trimethylhexanoyl) peroxide (Perloyl 355(S)), dilauroyl peroxide (Perloyl L), disuccinic acid peroxide (Perloyl SA), di-(3-methylbenzoyl) Peroxide, benzoyl (3-methylbenzoyl) peroxide, and dibenzoyl peroxide polymer blend (Niper BMT-K40, Niper BMT-M), dibenzoyl peroxide (Niper BW, Niper BO, Niper FF, Niper BS, Niper E, Niper NS), di(4-methylbenzoyl) peroxide (Niper PMB), di-n-propyl peroxydicarbonate (Perroyl NPP-5) 0M), diisopropyl peroxydicarbonate (Perloyl IPP-50, Perloyl IPP-27), di(4-t-butylcyclohexyl) peroxydicarbonate (Perloyl TCP), di(2-ethylhexyl) peroxydicarbonate (Perloyl OPP), di-sec-butyl peroxydicarbonate (Perloyl SBP), cumyl peroxyneodecanoate (Percumyl ND, Percumyl ND-50E), 1,1,3,3-Tetramethylbutyl peroxyneodecanoate (Perocta ND, Perocta ND-50E), t-hexyl peroxyneodecanoate (Perhexyl ND, Perhexyl ND-50E), t-butyl peroxyneodecanoate (Perbutyl ND, Perbutyl ND-50E), t-butyl peroxyneoheptanoate (Perbutyl NHP), t-hexyl peroxypivalate (Perhexyl PV, Perhexyl PV-50E), t- Butyl peroxypivalate (Perbutyl PV, Perbutyl PV-40E), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (Perocta O), 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (Perhexa 25 O), t-hexylperoxy-2-ethylhexanoate (Perhexyl O, Percure HO(N)), t-butylperoxy-2-ethylhexanoate (Perbutyl O , Percure O), t-hexylperoxyisopropyl monocarbonate (Perhexyl I), t-butylperoxy-3,5,5-trimethylhexanoate (Perbutyl 355), t-butylperoxylaurate (Perbutyl L), t-butylperoxy-2-ethylhexyl monocarbonate (Perbutyl E), t-hexylperoxybenzoate (Perhexyl Z), t-butylperoxyacetate (Perbutyl A), a polymer blend of t-butylperoxy-3-methylbenzoate and t-butylperoxybenzoate (Perbutyl ZT), t-butylperoxybenzoate (Perbutyl Z), t-butylperoxyallyl monocarbonate (Peromer AC), 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone (BTTB-25), 2,3-dimethyl-2,3-diphenylbutane (Nofumer BC-90), and the like can be mentioned. Among these, dialkyl-type organic peroxides are preferred. 2,5-dimethyl-2,5-di(t-butylperoxy)hexane is particularly preferred. Generally, the type and amount of organic peroxide used are selected taking into consideration the amount of active -O-O-, decomposition temperature, etc.

[0152] In this case, the crosslinking aid that can be used may be any compound that has reactivity with peroxy radicals and polymer radicals, such as -CH=CH ２ , -CH ２ CH=CH ２ , -CF=CF ２ , -C(CF ３ ) = CF ２ , -C(CH ３ ) = CF ２ , -CF=CF(CF ３ ), -CF=CF(CH ３ ), -C(C ６ H ５ ) = CF ２ , -CF=CF(C ６ H ５ ), —CH═CF ２ , -CF=CHF, -C(CF ３ )=CHF, -CF=CH(CF ３ ), -CH=CF(CF ３ ) and other polyfunctional compounds having functional groups such as ("C" in each formula) ６ H ５ " represents a phenyl group). Specific examples include triallyl cyanurate, triallyl isocyanurate (TAIC), triacryl formal, triallyl trimellitate, N,N'-n-phenylene bismaleimide, dipropargyl terephthalate, diallyl phthalate, tetraallyl terephthalate amide, 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.

[0153] Furthermore, examples of the crosslinking aid used together with the peroxide crosslinking agent include a crosslinking aid represented by the general formula (31): (Wherein, six R ３１ are each independently H, a halogen atom, or an optionally halogenated group having 1 to 5 carbon atoms which may contain an ether bond; Z ３１may also include compounds represented by a linear or branched alkylene group, cycloalkylene group, or (per)fluoropolyoxyalkylene group having 1 to 18 carbon atoms, which optionally contains a heteroatom and is optionally halogenated.

[0154] The compound represented by general formula (31) includes compounds represented by general formula (32): (wherein j is an integer of 2 to 10, preferably an integer of 4 to 8, and four R ３２ are each independently H, F, or an alkyl group or (per)fluoroalkyl group having 1 to 5 carbon atoms, a compound represented by general formula (33): (In the formula, Y ３１ are each independently F, Cl or H, and Y ３２ are each independently F, Cl, H or OR ３３ (where R ３３ is a branched or straight chain alkyl group which may be partially, substantially or completely fluorinated or chlorinated; Z ３３ is a divalent group having 2 to 10 carbon atoms, optionally fluorinated, optionally interrupted by ether linkages, preferably Z ３３ m is an integer of 3 to 5, -(CF ２ ) ｍ - group, and the compound represented by general formula (33) is preferably F ２ C=CF-O-(CF ２ ) ５ -O-CF=CF ２ a compound represented by general formula (34): (In the formula, Y ３１ , Y ３２ and Z ３３ is as described above, and R ３４ are each independently H, F, or an alkyl group or (per)fluoroalkyl group having 1 to 5 carbon atoms.

[0155] The crosslinking agent or the crosslinking aid used together with the peroxide crosslinking agent may be a crosslinking aid represented by the general formula (35):

[0156] (In the formula, R ３５ ~R ３７ are each independently a hydrogen atom, a fluorine atom, an alkyl group, a fluorinated alkyl group, or a substituted or unsubstituted aryl group, and R ３５ ~R ３７ At least one of R is a fluorine atom or a group containing a fluorine atom. m is an integer of 1 to 5. When m is 2 or more, m R ３５ ~R ３７ may be the same or different. A hydrogen atom on the benzene ring may be substituted. When m is 1, it is preferable that the compound has two or more of the structure.

[0157] The compound having the structure represented by general formula (36) includes compounds represented by general formula (36):

[0158] (In the formula, R ３５ ~R ３７ is as defined above, p is an integer of 0 to 2, and n is an integer of 2 to 6.), a compound represented by general formula (37):

[0159] (In the formula, R ３５ ~R ３７ is as above. ３８ is a single bond, -SO ２ -, -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 of 1 to 5. These groups may be partially or completely fluorinated.

[0160] The heteroatom-containing group is not particularly limited as long as it is a divalent group containing a heteroatom, and examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, a boron atom, and a phosphorus atom.

[0161] Examples of crosslinking agents used for polyol crosslinking include polyhydric alcohol compounds such as bisphenol A and bisphenol AF.

[0162] Examples of crosslinking agents used for polyamine crosslinking include polyamine compounds such as hexamethylenediamine carbamate, N,N'-dicinnamylidene-1,6-hexanediamine, and 4,4'-bis(aminocyclohexyl)methane carbamate.

[0163] Examples of crosslinking agents used for oxazole crosslinking, imidazole crosslinking, and thiazole crosslinking include those represented by the general formula (41):

[0164]

[0165] (In the formula, R ４１ Ha-SO ２ -, -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

[0166]

[0167] and R ４２ and R ４３ One side is -NH ２ and the other is -NHR ４４ , -NH ２ , —OH or —SH, and R ４４ is a hydrogen atom, a fluorine atom or a monovalent organic group, and preferably R ４２ Ga-NH ２ And R ４３ Ga-NHR ４４ Preferred specific examples of the alkylene group having 1 to 6 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group, and preferred specific examples of the perfluoroalkylene group having 1 to 10 carbon atoms include:

[0168]

[0169] These compounds are known as examples of bisdiaminophenyl compounds in JP-B 2-59177, JP-A 8-120146, etc.), bisaminophenol-based crosslinking agents, bisaminothiophenol-based crosslinking agents represented by general formula (42):

[0170] (R４１ As mentioned above, R ４５ are each independently any of the following groups:

[0171] Bisamidrazone crosslinking agents represented by general formula (43):

[0172]

[0173] (wherein, Rf ４１ is a perfluoroalkylene group having 1 to 10 carbon atoms), or an amidrazone crosslinking agent represented by the general formula (44):

[0174]

[0175] (wherein n is an integer of 1 to 10), a bisamidoxime crosslinking agent represented by the general formula (45): HN=CR ４５ R ４６ (In the formula, R ４５ , H, NH ２ , and N.H.R. ４７ and R ４６ is Ph, SO ２ H, N.R. ４８ R ４９ , 2-pyridine, and CH ２ CONH ２ and R ４７ Ph, NH ２ and CN, R ４８ is H, NHPh, CH ２ CONH ２ , a linear alkyl group having 1 to 8 carbon atoms, and a branched alkyl group having 1 to 8 carbon atoms; and R ４９ is Ph, COOC (CH ３ ) ３ , N.H. ２ , C.H. ２ COOH, CSNH ２ , CNHNH ３ ＋ Cl － , p-phenylCN, and COPh).

[0176] In addition, the crosslinking agent may be a compound represented by the general formula (46): X ４１ - (CH ２ ) ｎ -R ５０ - (CH ２ ) ｍ -X ４１ (In the formula, X ４１ each independently represents an alkyne group, a nitrile group, or Y ４１ Ｐ N ３ (Y ４１ SO, SO ２ , C ６ H ４ or CO, and p is 0 or 1, n and m are independently integers of 1 to 4, and R ５０ is selected from the group consisting of: i) a fluoroalkylene group having 3 to 10 carbon atoms, ii) a fluoroalkoxylene group having 3 to 10 carbon atoms, iii) a substituted arylene group, iv) an oligomer containing copolymerized units of vinylidene fluoride and perfluoro(methyl vinyl ether), v) an oligomer containing copolymerized units of vinylidene fluoride and hexafluoropropylene, vi) an oligomer containing copolymerized units of tetrafluoroethylene and perfluoro(methyl vinyl ether), and vii) an oligomer containing copolymerized units of tetrafluoroethylene and a hydrocarbon olefin.

[0177] Particularly preferred crosslinking agents include compounds having a plurality of 3-amino-4-hydroxyphenyl groups or 3-amino-4-mercaptophenyl groups, or compounds represented by the general formula (47):

[0178]

[0179] (In the formula, R ４１ , R ４２ and R ４３are as described above), and specific examples thereof include 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (general 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)phenyl] [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, and the like.

[0180] 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.

[0181] The content of at least one selected from the group consisting of inorganic nitrides, organotin compounds, compounds that generate ammonia, and crosslinking agents is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more 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, even more preferably 2.0 parts by mass or less, and particularly preferably 1.0 part by mass or less, relative to 100 parts by mass of the polymer blend.

[0182] (Other Components) The crosslinkable composition may contain other components in addition to the crosslinking agent.

[0183] The other components include, for example, fillers.

[0184] Examples of the filler include imide-based fillers having an imide structure such as polyimide, polyamideimide, 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.

[0185] Among these, carbon black, aluminum oxide, silicon oxide, yttrium oxide, silicon carbide, silicon nitride, polyimide, and carbon fluoride are preferred in terms of their shielding effect against various plasmas.

[0186] The inorganic fillers and organic fillers may be used alone or in combination of two or more.

[0187] In particular, in fields where high purity and non-staining properties are not required, ordinary additives that are blended into compositions, such as processing aids, plasticizers, colorants, etc., may be blended as needed, and one or more commonly used crosslinking agents or crosslinking aids different from those described above may also be blended.

[0188] The crosslinkable composition may contain an organic basic compound. Examples of the organic basic compound include a compound represented by the formula: CH ３ (CH ２ ) １７ -NH ２ Octadecylamine of formula: H ２ NC(O)-(CH ２ ) １１ -CH=CH-(CH ２ ) ７ CH ３ Erucamide of formula: H ２ NC(O)-(CH ２ ) ７ -CH=CH-(CH ２ ) ７ CH ３ Oleamide of formula: H ２N-(CH ２ ) ６ -NH ２ Hexamethylenediamine of the formula: Examples of suitable cyclopentadiene compounds include 1,8-diazabicycloundec-7-ene (DBU) of the formula:

[0189] The crosslinkable composition can be prepared by mixing the polymer blend and other components such as the crosslinking agent using a conventional polymer processing machine such as an open roll, a Banbury mixer, a kneader, or an internal mixer.

[0190] The above-mentioned crosslinkable composition can be suitably used as a molding material for obtaining an article by crosslinking and molding.

[0191] (Article) The article of the present disclosure can be obtained by crosslinking the above-described crosslinkable composition. The article of the present disclosure has appropriate hardness, small compression set at high temperatures, and is unlikely to experience large compression set even after use under harsh conditions.

[0192] The present disclosure also provides an article having a compression set of 50% or less when measured after 70 hours at 300°C, a compression set of less than 50% when measured after 70 hours at 200°C and then at 70°C for 70 hours, and a hardness of 65 or more when measured according to ASTM D2240. The article of the present disclosure has a moderate hardness, a small compression set at high temperatures, and is less likely to develop large compression set even after use under harsh conditions. The article of the present disclosure characterized by compression set and hardness preferably contains a polymer. The polymer is preferably the above-mentioned polymer blend.

[0193] In the following, both articles obtained by crosslinking the above-described crosslinkable compositions and articles characterized by compression set and hardness are described.

[0194] The hardness (Shore A, peak value) of the article is preferably 65 or more, more preferably 67 or more. The upper limit of the hardness is not particularly limited, but may be 90 or less, or 80 or less. The hardness of the article can be measured in accordance with JIS K6253.

[0195] As such, the article of the present disclosure has an appropriate hardness. Therefore, when the article of the present disclosure is used, for example, as a sealing material, the article is less likely to be crushed even when tightly fastened, and is less likely to crack even when used at high temperatures. If the hardness of the article is too low, it may be difficult to fasten tightly or may be more likely to crack when used at high temperatures. If the hardness is too high, the article may be difficult to compress, which may make it difficult to achieve excellent sealing properties.

[0196] The compression set (300°C) of the article measured after leaving it 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 the article at a compression rate of 25%, leaving it at 300°C for 70 hours, releasing the compression, leaving it at 23°C for 30 minutes, and then measuring the thickness of the article before and after compression.

[0197] Thus, the articles of the present disclosure have low compression set even when used at high temperatures exceeding 300°C.

[0198] The compression set (200°C) of the article measured after leaving it at 200°C for 70 hours and then at 70°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 leaving the article compressed at a compression rate of 25% at 200°C for 70 hours, leaving it at 70°C for 270 hours, releasing the compression, leaving it at 20°C for 30 minutes, and then measuring the thickness of the article after compression.

[0199] Thus, the article of the present disclosure is unlikely to suffer from large compression set even after use under harsh conditions. For example, when the article of the present disclosure is used as a sealing material for semiconductor manufacturing equipment, the sealing material may be used in a compressed state at temperatures of 200°C or higher while the semiconductor manufacturing equipment is operating. When the operation of the semiconductor manufacturing equipment is subsequently stopped, the sealing material remains compressed and is slowly cooled to room temperature, 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 disclosure has excellent high-temperature and low-temperature sealing properties and can withstand use under such harsh conditions.

[0200] A method for obtaining an article from the crosslinkable composition includes a method in which a preform is obtained by molding the crosslinkable composition as a molding material, and then crosslinking the preform. A preform can be obtained from the crosslinkable composition by a conventional method, and can be performed by known methods such as a method of heating and compressing in a mold, a method of forcing into a heated mold, or a method of extruding with an extruder. In the case of extruded products such as hoses and electric wires, articles can be obtained by performing heat crosslinking with steam or the like after extrusion.

[0201] The above crosslinking is called primary crosslinking, and can be carried out in the order of primary crosslinking and secondary crosslinking. The primary crosslinking is preferably carried out at 150 to 250°C for 5 to 120 minutes, and more preferably at 170 to 200°C for 5 to 60 minutes. Any known crosslinking means may be used as the crosslinking means, and examples thereof include press crosslinking.

[0202] The secondary crosslinking is preferably carried out at 250 to 320°C for 2 to 48 hours, and more preferably at 280 to 310°C for 5 to 24 hours. The secondary crosslinking may also be carried out at 180 to 320°C for 2 to 24 hours, or at 190 to 310°C for 5 to 20 hours. The temperature may be varied within this temperature range. Any known crosslinking method may be used as the crosslinking method, such as oven crosslinking. Crosslinking can be carried out, for example, in an air atmosphere or a nitrogen atmosphere.

[0203] The article of the present disclosure can be suitably used as a sealing material for semiconductor manufacturing equipment that requires heat resistance, particularly semiconductor manufacturing equipment that is exposed to high-density plasma. Examples of such sealing materials include O-rings, square rings, gaskets, packing, oil seals, bearing seals, and lip seals. The article can also be used for various polymer products used in semiconductor manufacturing equipment, such as diaphragms, tubes, hoses, various rubber rolls, and belts. It can also be used as a coating material or a lining material.

[0204] It should be noted that the semiconductor manufacturing equipment referred to in this disclosure is not limited to equipment specifically for manufacturing semiconductors, but broadly includes all manufacturing equipment used in the semiconductor field that requires a high degree of cleanliness, such as equipment for manufacturing liquid crystal panels and plasma panels, and examples thereof include the following:

[0205] (1) Etching equipment Dry etching equipment Plasma etching equipment Reactive ion etching equipment Reactive ion beam etching equipment Sputter etching equipment Ion beam etching equipment Wet etching equipment Ashing equipment (2) Cleaning equipment Dry etching cleaning equipment UV / O ３ Cleaning equipment Ion beam cleaning equipment Laser beam cleaning equipment Plasma cleaning equipment Gas etching cleaning equipment Extraction cleaning equipment Soxhlet extraction cleaning equipment High temperature and high pressure extraction cleaning equipment Microwave extraction cleaning equipment Supercritical extraction cleaning equipment (3) Exposure equipment Stepper Coater / Developer (4) Polishing equipment CMP equipment (5) Film formation equipment CVD equipment Sputtering equipment (6) Diffusion / ion implantation equipment Oxidation diffusion equipment Ion implantation equipment

[0206] The article of the present disclosure exhibits excellent performance as a sealant for, for example, a CVD apparatus, a plasma etching apparatus, a reactive ion etching apparatus, an ashing apparatus, or an excimer laser exposure apparatus.

[0207] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0208] <1> According to a first aspect of the present disclosure, there is provided a polymer blend containing a fluoroelastomer (a) and a crystalline fluoropolymer (b), wherein the fluoroelastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking moieties, and the crystalline fluoropolymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking moieties, the melting point of the polymer blend is 310 to 320°C, and the content of the crystalline fluoropolymer (b) in the polymer blend is 4.0 to 15.0 mass% based on the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b). <2> According to a second aspect of the present disclosure, there is provided the polymer blend according to the first aspect, wherein the Mooney viscosity at 170°C of the polymer blend is 70 to 120. <3> According to a third aspect of the present disclosure, there is provided a polymer blend according to the first or second aspect, wherein the content of nitrogen-containing crosslinking moieties in the polymer blend is 0.5 to 3.0 mol %, when all monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b) are taken as 100 mol %. <4> According to a fourth aspect of the present disclosure, there is provided a polymer blend according to any 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). <5> According to a fifth aspect of the present disclosure, there is provided a polymer blend according to any of the first to fourth aspects, wherein the fluoroalkyl vinyl ether units in the fluoroelastomer (a) are perfluoro(methyl vinyl ether) units. <6> According to a sixth aspect of the present disclosure, there is provided a polymer blend according to any one of the first to fifth aspects, wherein the fluoroelastomer (a) and the crystalline fluoropolymer (b) contain a monomer unit having a nitrogen-containing crosslinkable group.<7> According to a seventh aspect of the present disclosure, there is provided a polymer blend according to any one of the first to sixth aspects, which is obtained by a production method comprising preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b), and coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion. <8> According to an eighth aspect of the present disclosure, there is provided a polymer blend according to any of the first to seventh aspects, obtained by a production method comprising: (1-1) preparing an aqueous dispersion containing a fluoroelastomer (a) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-2) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-3) preparing an aqueous dispersion containing the fluoroelastomer (a) and the crystalline fluoropolymer (b) by mixing the aqueous dispersion containing the fluoroelastomer (a) with an aqueous dispersion containing the crystalline fluoropolymer (b); and (1-4) obtaining the polymer blend by coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion. <9> According to a ninth aspect of the present disclosure, there is provided a polymer blend according to any one of the first to eighth aspects, wherein the content of nitrogen-containing crosslinking moieties in the fluoroelastomer (a) is 0.5 to 3.0 mol % when all monomer units constituting the fluoroelastomer (a) are taken as 100 mol %. <10> According to a tenth aspect of the present disclosure, there is provided a polymer blend according to any one of the first to ninth aspects, wherein the content of nitrogen-containing crosslinking moieties in the crystalline fluoropolymer (b) is 0.5 to 3.0 mol % when all monomer units constituting the crystalline fluoropolymer (b) are taken as 100 mol %.<11> According to an eleventh aspect of the present disclosure, there is provided a polymer blend according to any one of the first to seventh aspects, obtained by a production method comprising: (2-1) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium, and then (2-2) preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of the crystalline fluoropolymer (b) and the aqueous medium, and (2-3) coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion. <12> According to a twelfth aspect of the present disclosure, 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. <13> According to a thirteenth aspect of the present disclosure, there is provided an article obtained by crosslinking the crosslinkable composition according to the twelfth aspect. <14> According to a fourteenth aspect of the present disclosure, there is provided an article according to the thirteenth aspect, which has a compression set of 50% or less measured after being left at 300°C for 70 hours, a compression set of less than 50% measured after being left at 200°C for 70 hours and then at 70°C for 70 hours, and a hardness of 65 or more measured in accordance with ASTM D2240.<15> According to a fifteenth aspect of the present disclosure, there is provided a method for producing a polymer blend according to any of the first to tenth aspects, comprising: (1-1) preparing an aqueous dispersion containing a fluoroelastomer (a) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-2) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-3) mixing the aqueous dispersion containing the fluoroelastomer (a) with an aqueous dispersion containing the crystalline fluoropolymer (b) to prepare an aqueous dispersion containing the fluoroelastomer (a) and the crystalline fluoropolymer (b); and (1-4) coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion, thereby obtaining the polymer blend. <16> According to a sixteenth aspect of the present disclosure, there is provided a method for producing a polymer blend according to any of the first to seventh and eleventh aspects, comprising: (2-1) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium, and then (2-2) preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of the crystalline fluoropolymer (b) and the aqueous medium; and (2-3) coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion, thereby obtaining the polymer blend.<17> According to a seventeenth aspect of the present disclosure, there is provided a production method according to the sixteenth aspect, which comprises the steps of: (2-1) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) in a reaction vessel, and then (2-2) introducing a fluoroalkyl vinyl ether into the reaction vessel while continuing a polymerization reaction in the reaction vessel, thereby polymerizing tetrafluoroethylene, the fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group. <18> According to an eighteenth aspect of the present disclosure, there is provided an article having a compression set of 50% or less measured after being left at 300°C for 70 hours, a compression set of less than 50% measured after being left at 200°C for 70 hours and then at 70°C for 70 hours, and a hardness of 65 or greater measured in accordance with ASTM D2240.

[0209] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0210] The values ​​in the examples were measured by the following methods.

[0211] (Mooney Viscosity) 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.

[0212] (Monomer Composition) The monomer composition of the polymer blend, fluoroelastomer and crystalline fluoropolymer is １９ The content of the cyano group-containing monomer unit was determined by the following method (IR).

[0213] (Cyano Group Content and Cyano Group-Containing Monomer Unit Content) The cyano group content and cyano group-containing monomer unit content of the polymer blend, fluoroelastomer and crystalline fluoropolymer were measured by infrared spectroscopy (IR).

[0214] (Glass Transition Temperature) The glass transition temperature of the polymer blend was determined by obtaining a DSC curve using a differential scanning calorimeter (X-DSC7000, manufactured by Hitachi High-Tech Science Corporation) by heating 3 mg of a sample at 20°C / min, and the temperature was determined as the midpoint between two intersections of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve.

[0215] (Content of crystalline fluoropolymer (b)) The content of crystalline fluoropolymer (b) in the polymer blend was measured by precisely weighing about 10 mg of the polymer blend that had not been heated to a temperature of 300°C or higher, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric differential thermal analyzer). The aluminum pan was heated in an air atmosphere in the temperature range from 25°C to 600°C at a rate of 10°C / min to obtain a TG curve, and the weight loss rate was calculated from the obtained TG curve to determine the content. Table 1 shows the content of crystalline fluoropolymer (b) in the polymer blend relative to the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b).

[0216] (Melting Point) The melting point of the polymer blend was measured by precisely weighing about 10 mg of the polymer blend that had not been heated to temperatures above 300°C, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric differential thermal analyzer). The aluminum pan was heated in an air atmosphere from 25°C to 600°C at a rate of 10°C / min to obtain a DTA curve, and the temperature corresponding to the peak in the obtained DTA curve was identified as the melting point of the polymer blend. The presence or absence of a melting point of the fluoroelastomer was also confirmed using the method for measuring the melting point of the polymer blend. In Table 1, "N.D." indicates that no clear peak was observed in the DTA curve.

[0217] (Hardness (Shore A) Peak) Using an article having a thickness of 2 mm, the hardness (Shore A) was measured (peak value) in accordance with JIS-K6253.

[0218] (Compression set (300°C)) Compression set was measured in accordance with the method described in ASTM D395 or JIS K6262. The O-rings produced in the examples and comparative examples were compressed at room temperature to a compression rate of 25% (an O-ring with a thickness (wire diameter) of 3.5 mm was compressed to a thickness of 2.625 mm) using a compression device. Next, the compression device with the compressed O-ring fixed thereto was placed in an electric furnace and left at 300°C for 70 hours, after which the compression device was removed from the electric furnace. The O-ring was removed from the compression device, and the removed O-ring was left in a thermostatic chamber at 23°C for 30 minutes, and the thickness (t ２ ) was measured. Compression set was calculated using the following formula. The closer the compression set is to 0%, the better the compression set property of the article is. Compression set (%) = (t ０ -t ２ ) / (t ０ -t １ ) x 100 t ０ t: Original thickness of O-ring (mm) １ t: Spacer thickness (mm) ２ : Thickness of the O-ring after compression test (mm) In the above test, t ０ = 3.5 mm, t １ = 2.625 mm.

[0219] (Compression set (200°C → 70°C)) Compression set was measured in accordance with the method described in ASTM D395 or JIS K6262. The O-rings produced in the examples and comparative examples were compressed to a compression rate of 25% at room temperature using a compression device (an O-ring with a thickness (wire diameter) of 3.5 mm was compressed to a thickness of 2.625 mm). Next, the compression device with the compressed O-ring fixed thereto was placed in an electric furnace and left at 200°C for 70 hours, and then the compression device was removed from the electric furnace. Thereafter, the compression device with the compressed O-ring fixed thereto was placed in another electric furnace and left at 70°C for 70 hours. The O-ring was removed from the compression device, and the removed O-ring was left in a constant temperature room at 23°C for 30 minutes, and the thickness (t ２ The compression set was calculated using the following formula: Compression set (%) = (t ０ -t ２ ) / (t０ -t １ ) x 100 t ０ t: Original thickness of O-ring (mm) １ t: Spacer thickness (mm) ２ : Thickness of the O-ring after compression test (mm) In the above test, t ０ = 3.5 mm, t １ = 2.625 mm.

[0220] Example 1 43 g of ammonium perfluorohexanoate and 0.08 g of ammonium carbonate were placed in a 2 L stainless steel autoclave, followed by the addition of 790 g of deionized and degassed water. The reaction vessel was sealed, and the atmosphere in the system was replaced with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ After charging 0.33 g of CN (CNVE), TFE was charged until the pressure reached 0.29 MPa, and the pressure and temperature in the vessel were maintained. 3.0 g of ammonium persulfate (APS) was charged as a polymerization initiator. TFE was charged so that the reaction pressure was constant at 0.29 MPa, and a total of 0.27 g of CNVE was continuously charged until 25.0 g of TFE was added. Finally, after TFE was charged, the pressure in the vessel was reduced to 0.19 MPa, and then 40.4 g of PMVE was charged. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 56.0 / 44.0 mol% was introduced into the reaction vessel, and the pressure was introduced so that it reached 0.85 MPa. Subsequently, 185.0 g of additional gas (TFE / PMVE = 56.0 / 44.0 mol%) was continuously introduced to maintain a constant pressure of 0.85 MPa. At the same time, a total of 4.7 g of CNVE was continuously charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reactor was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reactor and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70 °C for 24 hours to obtain 218 g of a polymer blend.

[0221] TG / DTA measurement of the obtained polymer blend showed a melting point of 317.7 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 10.6 wt%. DSC measurement also revealed that the glass transition temperature was -4.6 ° C. NMR analysis also revealed that TFE / PMVE = 55.2 / 44.8 mol%, and IR analysis revealed that CNVE was 0.57 mol%. The Mooney viscosity was 72.

[0222] Example 2: 43 g of ammonium perfluorohexanoate and 0.08 g of ammonium carbonate were added to a 2 L SUS autoclave, followed by 790 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, and 0.16 g of CNVE was added. TFE was then added to the vessel until the pressure reached 0.29 MPa, and the pressure and temperature inside the vessel were maintained. 1.6 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.38 g of CNVE was continuously added until 20.0 g of TFE had been added. Finally, after the TFE had been added, the pressure inside the vessel was reduced to 0.19 MPa, and 40.4 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 54.0 / 46.0 mol% was introduced into the reactor, and the pressure was reduced to 0.85 MPa. Then, 185.0 g of an additional gas of TFE / PMVE = 54.0 / 46.0 mol% was continuously introduced so that the pressure remained constant at 0.85 MPa. At the same time, a total of 4.7 g of CNVE was continuously charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reactor was depressurized until the pressure reached atmospheric pressure. The aqueous dispersion was removed from the reactor and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70 ° C. for 24 hours to obtain 213 g of a polymer blend.

[0223] TG / DTA measurement of the obtained polymer blend showed a melting point of 316.5 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 9.4 wt%. DSC measurement also revealed that the glass transition temperature was -5.0 ° C. NMR analysis also revealed that TFE / PMVE = 53.5 / 46.5 mol%, and IR analysis revealed that CNVE was 0.56 mol%. The Mooney viscosity was 86.

[0224] Example 3: 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, and 0.65 g of CNVE was added. TFE was then added to the vessel until the pressure reached 0.29 MPa, and the pressure and temperature inside the vessel were maintained. 8.5 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.65 g of CNVE was continuously added until 34.0 g of TFE had been added. Finally, after the TFE had been added, the pressure inside the vessel was reduced to 0.19 MPa, and 145 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 58.0 / 42.0 mol% was introduced into the reaction vessel and introduced so that the pressure was 0.85 MPa. Thereafter, 660 g of additional gas of TFE / PMVE = 58.0 / 42.0 mol% was continuously introduced so that the pressure remained constant at 0.85 MPa. At the same time, a total of 14.3 g of CNVE was continuously charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reaction vessel was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was coagulated with nitric acid water, washed with water, and vacuum dried at 70 ° C. for 24 hours to obtain 718 g of a polymer blend.

[0225] TG / DTA measurement of the obtained polymer blend showed a melting point of 313.7 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 5.5 wt%. DSC measurement also revealed that the glass transition temperature was -5.3 ° C. NMR analysis also revealed that TFE / PMVE = 58.6 / 41.4 mol%, and IR analysis revealed that CNVE was 0.55 mol%. The Mooney viscosity was 90.

[0226] Example 4: 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, and 0.54 g of CNVE was added. TFE was then added to the vessel until the pressure reached 0.29 MPa, and the pressure and temperature inside the vessel were maintained. 5.4 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.65 g of CNVE was continuously added until 34.0 g of TFE had been added. Finally, after the TFE had been added, the pressure inside the vessel was reduced to 0.19 MPa, and 145 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 58.0 / 42.0 mol% was introduced into the reaction vessel and introduced so that the pressure was 0.85 MPa. Thereafter, 660 g of additional gas of TFE / PMVE = 58.0 / 42.0 mol% was continuously introduced so that the pressure remained constant at 0.85 MPa. At the same time, a total of 14.3 g of CNVE was continuously charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reaction vessel was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70 ° C. for 24 hours to obtain 700 g of a polymer blend.

[0227] TG / DTA measurement of the obtained polymer blend showed a melting point of 314.3 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 5.0 wt%. DSC measurement also revealed that the glass transition temperature was -5.3 ° C. NMR analysis also revealed that TFE / PMVE = 58.9 / 41.1 mol%, and IR analysis revealed that CNVE was 0.57 mol%. The Mooney viscosity was 115.

[0228] Example 5: 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, and 0.54 g of CNVE was added. TFE was then added to the vessel until the pressure reached 0.29 MPa, and the pressure and temperature inside the vessel were maintained. 9.2 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.97 g of CNVE was continuously added until 51.0 g of TFE was added. Finally, after the addition of TFE was completed, the pressure inside the vessel was reduced to 0.19 MPa, and 145 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 58.0 / 42.0 mol% was introduced into the reaction vessel and introduced so that the pressure was 0.85 MPa. Thereafter, 660 g of additional gas of TFE / PMVE = 58.0 / 42.0 mol% was continuously introduced so that the pressure remained constant at 0.85 MPa. At the same time, a total of 14.3 g of CNVE was continuously charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reaction vessel was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70 ° C. for 24 hours to obtain 730 g of a polymer blend.

[0229] TG / DTA measurement of the obtained polymer blend showed a melting point of 314.4 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 7.6 wt%. DSC measurement also revealed that the glass transition temperature was -5.5 ° C. NMR analysis also revealed that TFE / PMVE = 58.1 / 41.9 mol%, and IR analysis revealed that CNVE was 0.53 mol%. The Mooney viscosity was 87.

[0230] Example 6: 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5°C, and 0.54 g of CNVE was added. TFE was then added to the vessel until the pressure reached 0.29 MPa, and the pressure and temperature inside the vessel were maintained. 7.2 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.97 g of CNVE was continuously added until 51.0 g of TFE had been added. Finally, after the TFE had been added, the pressure inside the vessel was reduced to 0.19 MPa, and 124 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 62.5 / 37.5 mol% was introduced into the reactor until the pressure reached 0.85 MPa. Subsequently, 720 g of an additional gas of TFE / PMVE = 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 charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reactor was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reactor and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70 ° C. for 24 hours to obtain 700 g of a polymer blend.

[0231] TG / DTA measurement of the obtained polymer blend showed a melting point of 312.9 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 5.9 wt%. DSC measurement also revealed that the glass transition temperature was -4.1 ° C. NMR analysis also revealed that TFE / PMVE = 63.5 / 36.5 mol%, and IR analysis revealed that CNVE was 0.55 mol%. The Mooney viscosity was 111.

[0232] Example 7: 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 67.5 ° C., and 0.54 g of CNVE was added. Then, TFE was added to a pressure of 0.36 MPa, and the pressure and temperature in the vessel were maintained. 1.1 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.36 MPa, and a total of 0.45 g of CNVE was continuously added until 42.0 g of TFE was added. Finally, after the TFE was added, the pressure in the vessel was reduced to 0.26 MPa, and 115 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and 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 until the pressure remained constant at 0.85 MPa. At the same time, a total of 17.4 g of CNVE was continuously charged. Furthermore, when the polymerization rate began to decrease, a 2% by mass aqueous solution of APS was appropriately added. The total amount of the 2% by mass aqueous solution of APS added after the start of polymerization was 20 mL. When all the additional gas and CNVE were charged, stirring was stopped, and the reaction vessel was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70°C for 24 hours to obtain 730 g of a polymer blend.

[0233] TG / DTA measurement of the obtained polymer blend showed a melting point of 317.5 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 5.2 wt%. DSC measurement also revealed that the glass transition temperature was -2.6 ° C. NMR analysis also revealed that TFE / PMVE = 66.2 / 33.8 mol%, and IR analysis revealed that CNVE was 0.61 mol%. The Mooney viscosity was 111.

[0234] Example 8: 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 67.5 ° C., and 0.54 g of CNVE was added. TFE was then added to the vessel until the pressure reached 0.36 MPa, and the pressure and temperature inside the vessel were maintained. 1.1 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.36 MPa, and a total of 0.97 g of CNVE was continuously added until 51.0 g of TFE had been added. Finally, after the TFE had been added, the pressure inside the vessel was reduced to 0.26 MPa, and 115 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and 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 until the pressure remained constant at 0.85 MPa. At the same time, a total of 17.4 g of CNVE was continuously charged. Furthermore, when the polymerization rate began to decrease, a 2% by mass aqueous solution of APS was appropriately added. The total amount of the 2% by mass aqueous solution of APS added after the start of polymerization was 20 mL. When all the additional gas and CNVE were charged, stirring was stopped, and the reaction vessel was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70°C for 24 hours, yielding 742 g of a polymer blend.

[0235] TG / DTA measurement of the obtained polymer blend showed a melting point of 316.2 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 7.2 wt%. DSC measurement also revealed that the glass transition temperature was -2.8 ° C. NMR analysis also revealed that TFE / PMVE = 66.6 / 33.4 mol%, and IR analysis revealed that CNVE was 0.59 mol%. The Mooney viscosity was 108.

[0236] Comparative Example 1 43 g of ammonium perfluorohexanoate and 0.08 g of ammonium carbonate were added to a 2 L SUS autoclave, followed by 790 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 0.16 g of CNVE was added. Then, TFE was added to a pressure of 0.29 MPa, and the pressure and temperature in the vessel were maintained. 1.6 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.19 g of CNVE was continuously added until 10.0 g of TFE was added. Finally, after the TFE was added, the pressure in the vessel was reduced to 0.19 MPa, and 40.4 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 54.0 / 46.0 mol% was introduced into the reactor until the pressure reached 0.85 MPa. Subsequently, 198 g of an additional gas of TFE / PMVE = 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 charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reactor was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reactor and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70 ° C. for 24 hours to obtain 213 g of a polymer blend.

[0237] TG / DTA measurements of the resulting polymer blend revealed no observed crystalline fluoropolymer (b) content, and the weight loss rate indicated that the content was 3.6 wt%. Furthermore, DSC measurements indicated that the glass transition temperature was -5.4°C. Furthermore, NMR analysis indicated that the TFE / PMVE ratio was 54.4 / 45.6 mol%, and IR analysis indicated that the CNVE content was 0.56 mol%. Furthermore, the Mooney viscosity was 96.

[0238] Comparative Example 2: 155 g of ammonium perfluorohexanoate and 0.28 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2,880 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 2.24 g of CNVE was added. A mixed gas of TFE / PMVE = 24.0 / 76.0 mol% was then added up to a pressure of 0.85 MPa, and the pressure and temperature inside the vessel were maintained. 15.0 g of ammonium persulfate (APS) was added as a polymerization initiator. 810 g of additional gas of TFE / PMVE = 58.0 / 42.0 mol% was continuously introduced to maintain the reaction pressure at a constant 0.85 MPa. At the same time, a total of 25.6 g of CNVE was continuously added. After all the additional gas and CNVE had been charged, the stirring was stopped, the reactor was depressurized to atmospheric pressure, and the aqueous dispersion was removed from the reactor and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70°C for 24 hours to obtain 828 g of a polymer blend.

[0239] TG / DTA measurements of the resulting polymer blend showed that no melting point was observed, and the weight loss rate indicated that the content of crystalline fluoropolymer (b) was 0 wt%. Furthermore, DSC measurements showed that the glass transition temperature was -5.2°C. Furthermore, NMR analysis indicated that TFE / PMVE = 58.0 / 42.0 mol%, and IR analysis indicated that CNVE was 1.20 mol%. Furthermore, the Mooney viscosity was 80.

[0240] Comparative Example 3 43 g of ammonium perfluorohexanoate and 0.08 g of ammonium carbonate were added to a 2 L SUS autoclave, followed by 790 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 0.64 g of CNVE was added, followed by TFE to a pressure of 0.29 MPa, and the pressure and temperature in the vessel were maintained. 2.2 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.49 g of CNVE was continuously added until 17.0 g of TFE was added. Finally, after the TFE was added, the pressure in the vessel was reduced to 0.19 MPa, and 40.4 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 58.0 / 42.0 mol% was introduced into the reaction vessel and introduced so that the pressure was 0.85 MPa. Then, 198 g of additional gas of TFE / PMVE = 58.0 / 42.0 mol% was continuously introduced so that the pressure remained constant at 0.85 MPa. At the same time, a total of 4.7 g of CNVE was continuously charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reaction vessel was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reaction vessel and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70 ° C. for 24 hours to obtain 217 g of a polymer blend.

[0241] TG / DTA measurement of the obtained polymer blend showed a melting point of 304.0 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 8.0 wt%. DSC measurement also revealed that the glass transition temperature was -5.0 ° C. NMR analysis also revealed that TFE / PMVE = 58.0 / 42.0 mol%, and IR analysis revealed that CNVE was 0.58 mol%. The Mooney viscosity was 92.

[0242] Comparative Example 4 43 g of ammonium perfluorohexanoate and 0.08 g of ammonium carbonate were added to a 2 L SUS autoclave, followed by 790 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 0.16 g of CNVE was added, followed by TFE to a pressure of 0.29 MPa, and the pressure and temperature in the vessel were maintained. 1.8 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.08 g of CNVE was continuously added until 22.0 g of TFE was added. Finally, after the TFE was added, the pressure in the vessel was reduced to 0.19 MPa, and 40.4 g of PMVE was added. After charging PMVE, the pressure was reduced to 0.735 MPa, and then an additional gas of TFE / PMVE = 58.0 / 42.0 mol% was introduced into the reactor until the pressure reached 0.85 MPa. Subsequently, 188.0 g of an additional gas of TFE / PMVE = 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 charged. When all the additional gas and CNVE were charged, stirring was stopped, and the reactor was depressurized until atmospheric pressure was reached. The aqueous dispersion was removed from the reactor and cooled. The resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum-dried at 70 ° C. for 24 hours to obtain 213 g of a polymer blend.

[0243] TG / DTA measurement of the obtained polymer blend showed a melting point of 328.0 ° C., and the weight loss rate revealed that the content of crystalline fluoropolymer (b) was 10.0 wt%. Furthermore, DSC measurement revealed that the glass transition temperature was -5.0 ° C. Furthermore, NMR analysis revealed that TFE / PMVE = 58.0 / 42.0 mol%, and IR analysis revealed that CNVE was 0.58 mol%. Furthermore, the Mooney viscosity was 86.

[0244] Synthesis Example of Fluoroelastomer (a): 155 g of ammonium perfluorohexanoate and 0.28 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2,880 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 1.21 g of CNVE was added. A mixed gas of TFE / PMVE = 24.0 / 76.0 mol% was then added to the system to raise the pressure to 0.85 MPa, and the pressure and temperature inside the vessel were maintained. 15.0 g of ammonium persulfate (APS) was added as a polymerization initiator. 810 g of additional gas of TFE / PMVE = 58.0 / 42.0 mol% was continuously introduced to maintain the reaction pressure at a constant 0.85 MPa. At the same time, a total of 19.8 g of CNVE was continuously added. After all the additional gas and CNVE had been charged, the stirring was stopped, the reactor was depressurized to atmospheric pressure, the aqueous dispersion was removed from the reactor, and cooled. A portion of the resulting aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70°C for 24 hours.

[0245] TG / DTA measurement of the obtained fluoroelastomer (a) showed that no melting point was observed, and the weight loss rate showed that the content of crystalline fluoropolymer (b) was 0 wt%. In addition, NMR analysis showed that TFE / PMVE = 58.0 / 42.0 mol%, and IR analysis showed that CNVE was 0.60 mol%. In addition, the Mooney viscosity was 74.

[0246] Synthesis Example of Crystalline Fluoropolymer (b1) 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 0.54 g of CNVE was added, followed by TFE to a pressure of 0.29 MPa, and the pressure and temperature in the vessel were maintained. 5.4 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.65 g of CNVE was continuously added until 34.0 g of TFE was added. Finally, after the TFE was added, the pressure in the vessel was reduced to 0.19 MPa, and then stirring was stopped. The reaction vessel was depressurized until atmospheric pressure was reached, and the aqueous dispersion was removed from the reaction vessel and cooled. A part of the obtained dispersion was coagulated with aqueous nitric acid, washed with water, and dried in vacuum at 70° C. for 24 hours.

[0247] IR analysis of the resulting crystalline fluoropolymer (b1) revealed that the CNVE was 0.90 mol %.

[0248] Synthesis Example of Crystalline Fluoropolymer (b2) 145 g of ammonium perfluorohexanoate and 0.26 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 0.1 g of CNVE was added, followed by TFE to a pressure of 0.29 MPa, and the pressure and temperature in the vessel were maintained. 5.4 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 0.04 g of CNVE was continuously added until 34.0 g of TFE was added. Finally, after the TFE was added, the pressure in the vessel was reduced to 0.19 MPa, and then stirring was stopped. The reaction vessel was depressurized until atmospheric pressure was reached, and the aqueous dispersion was removed from the reaction vessel and cooled. A part of the obtained dispersion was coagulated with aqueous nitric acid, washed with water, and dried in vacuum at 70° C. for 24 hours.

[0249] IR analysis of the resulting crystalline fluoropolymer (b1) revealed that the CNVE was 0.10 mol %.

[0250] Synthesis Example of Crystalline Fluoropolymer (b3) 145 g of ammonium perfluorohexanoate and 2.16 g of ammonium carbonate were added to a 6 L SUS autoclave, followed by 2660 g of deionized and degassed water. The reaction vessel was sealed, and the system was purged with nitrogen to remove oxygen. The reaction vessel was heated to 54.5 ° C., and 0.54 g of CNVE was added, followed by TFE to a pressure of 0.29 MPa, and the pressure and temperature in the vessel were maintained. 5.4 g of ammonium persulfate (APS) was added as a polymerization initiator. TFE was added so that the reaction pressure remained constant at 0.29 MPa, and a total of 1.71 g of CNVE was continuously added until 34.0 g of TFE was added. Finally, after the TFE was added, the pressure in the vessel was reduced to 0.19 MPa, and then stirring was stopped. The reaction vessel was depressurized until atmospheric pressure was reached, and the aqueous dispersion was removed from the reaction vessel and cooled. A part of the obtained dispersion was coagulated with aqueous nitric acid, washed with water, and dried in vacuum at 70° C. for 24 hours.

[0251] IR analysis of the resulting crystalline fluoropolymer (b1) revealed that the CNVE was 3.20 mol %.

[0252] Example 9: 995 g of an aqueous dispersion of fluoroelastomer (a) and 846 g of an aqueous dispersion of fluoropolymer (b1) were introduced into a vessel equipped with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70°C for 24 hours to obtain 220 g of a polymer blend. TG / DTA measurement of the obtained polymer blend showed a melting point of 318°C, and the weight loss rate indicated that the content of crystalline fluoropolymer (b) was 4.7 wt%. DSC measurement also showed that the glass transition temperature was -5.0°C. The Mooney viscosity was 86.

[0253] Example 10: 942 g of an aqueous dispersion of fluoroelastomer (a) and 1692 g of an aqueous dispersion of fluoropolymer (b1) were introduced into a vessel equipped with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70°C for 24 hours to obtain 220 g of a polymer blend. TG / DTA measurement of the obtained polymer blend showed a melting point of 318°C, and the weight loss rate indicated that the content of crystalline fluoropolymer (b) was 11.2 wt%. DSC measurement also showed that the glass transition temperature was -5.0°C. The Mooney viscosity was 92.

[0254] Comparative Example 5: 890 g of an aqueous dispersion of fluoroelastomer (a) and 2,538 g of an aqueous dispersion of fluoropolymer (b1) were introduced into a vessel equipped with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70°C for 24 hours to obtain 220 g of a polymer blend. TG / DTA measurement of the obtained polymer blend showed a melting point of 318°C, and the weight loss rate indicated that the content of crystalline fluoropolymer (b) was 15.7 wt%. DSC measurement also showed that the glass transition temperature was -4.8°C. The Mooney viscosity was 92.

[0255] Comparative Example 6: 953 g of an aqueous dispersion of fluoroelastomer (a) and 1,523 g of an aqueous dispersion of fluoropolymer (b2) were introduced into a vessel equipped with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70°C for 24 hours to obtain 220 g of a polymer blend. TG / DTA measurement of the obtained polymer blend showed a melting point of 328°C, and the weight loss rate indicated that the content of crystalline fluoropolymer (b) was 10.2 wt%. DSC measurement also showed a glass transition temperature of -4.8°C. The Mooney viscosity was 82.

[0256] Comparative Example 7: 963 g of an aqueous dispersion of fluoroelastomer (a) and 1,353 g of an aqueous dispersion of fluoropolymer (b2) were introduced into a vessel equipped with a stirrer to prepare a mixed aqueous dispersion. The prepared mixed aqueous dispersion was coagulated with aqueous nitric acid, washed with water, and vacuum dried at 70°C for 24 hours to obtain 220 g of a polymer blend. TG / DTA measurement of the obtained polymer blend showed a melting point of 299°C, and the weight loss rate indicated that the content of crystalline fluoropolymer (b) was 8.2 wt%. DSC measurement also showed that the glass transition temperature was -4.9°C. The Mooney viscosity was 87.

[0257] To 100 parts by mass of the fluoroelastomer (a) in the polymer blends prepared in the Examples and Comparative Examples, 0.9 parts by mass of the crosslinking agent 2,2-bis[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane was added, kneaded with an open roll, and crosslinked by pressing at 180°C for 30 minutes. Further, oven crosslinking was carried out in an air oven at 290°C for 18 hours to prepare 2 mm thick sheets and P24 size O-rings. The hardness was measured using the obtained sheets, and the compression set was measured using the obtained O-rings. The results are shown in Tables 1 to 3.

[0258]

[0259]

[0260]

[0261]

Claims

1. A polymer blend containing a fluoroelastomer (a) and a crystalline fluoropolymer (b), the fluoroelastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking moieties; The crystalline fluoropolymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking moieties; The melting point of the polymer blend is 310 to 320°C, A polymer blend in which the content of the crystalline fluoropolymer (b) in the polymer blend is 4.0 to 15.0% by mass based on the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b).

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

3. The content of nitrogen-containing crosslinking moiety in the polymer blend is 0.5 to 3.0 mol%, when the total monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b) are 100 mol%, the polymer blend according to claim 1 or 2.

4. The polymer blend according to claim 1 or 2, wherein the content ratio of tetrafluoroethylene units and 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).

5. 3. The polymer blend of claim 1 or 2, wherein the fluoroalkyl vinyl ether units in fluoroelastomer (a) are perfluoro(methyl vinyl ether) units.

6. 3. The polymer blend of claim 1 or 2, wherein the fluoroelastomer (a) and the crystalline fluoropolymer (b) contain monomer units having nitrogen-containing crosslinkable groups.

7. The polymer blend according to claim 1 or 2, which can be obtained by the production method of preparing an aqueous dispersion containing fluoroelastomer (a) and crystalline fluoropolymer (b), and coagulating the fluoroelastomer (a) and crystalline fluoropolymer (b) in said aqueous dispersion.

8. (1-1) preparing an aqueous dispersion containing a fluoroelastomer (a) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-2) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-3) Mixing an aqueous dispersion containing a fluoroelastomer (a) with an aqueous dispersion containing a crystalline fluoropolymer (b) to prepare an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b); (1-4) The fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion are coagulated to obtain the polymer blend.

3. A polymer blend according to claim 1 or 2, obtained by the process.

9. The polymer blend according to claim 1 or 2, wherein the content of nitrogen-containing crosslinking moieties in the fluoroelastomer (a) is 0.5 to 3.0 mol%, when the total amount of all monomer units constituting the fluoroelastomer (a) is 100 mol%.

10. The content of nitrogen-containing crosslinking moiety in the crystalline fluoropolymer (b) is 0.5 to 3.0 mol%, when the total monomer units constituting the crystalline fluoropolymer (b) is 100 mol%.

11. (2-1) An aqueous dispersion containing a crystalline fluoropolymer (b) is prepared by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium, and then (2-2) In the presence of the crystalline fluoropolymer (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 fluoroelastomer (a) and the crystalline fluoropolymer (b); (2-3) Coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion 3. A polymer blend according to claim 1 or 2, obtained by the process.

12. A crosslinkable composition comprising the polymer blend according to claim 1 or 2 and at least one member selected from the group consisting of inorganic nitrides, organotin compounds, compounds that generate ammonia, and crosslinking agents.

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

14. The compression set measured after leaving it at 300°C for 70 hours is 50% or less, The compression set measured after leaving the film at 200°C for 70 hours and then at 70°C for 70 hours is less than 50%, Hardness measured according to ASTM D2240 is 65 or more 14. The article of claim 13.

15. A method for producing the polymer blend of claim 1 or 2, comprising: (1-1) preparing an aqueous dispersion containing a fluoroelastomer (a) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-2) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-3) Mixing an aqueous dispersion containing a fluoroelastomer (a) with an aqueous dispersion containing a crystalline fluoropolymer (b) to prepare an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b); (1-4) The fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion are coagulated to obtain the polymer blend. Manufacturing method.

16. A method for producing the polymer blend of claim 1 or 2, comprising: (2-1) An aqueous dispersion containing a crystalline fluoropolymer (b) is prepared by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium, and then (2-2) In the presence of the crystalline fluoropolymer (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 fluoroelastomer (a) and the crystalline fluoropolymer (b); (2-3) The fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion are coagulated to obtain the polymer blend. Manufacturing method.

17. (2-1) After preparing an aqueous dispersion containing the crystalline fluoropolymer (b) in a reaction vessel, (2-2) While continuing the polymerization reaction in the reaction vessel, a fluoroalkyl vinyl ether is introduced into the reaction vessel to polymerize tetrafluoroethylene, the fluoroalkyl vinyl ether, and the monomer having a nitrogen-containing crosslinkable group. The method of claim 16.

18. The compression set measured after leaving it at 300°C for 70 hours is 50% or less, The compression set measured after leaving the film at 200°C for 70 hours and then at 70°C for 70 hours is less than 50%, Hardness measured according to ASTM D2240 is 65 or more Goods.