WO2023162783A1 - Elastomer composition - Google Patents

Elastomer composition Download PDF

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Publication number
WO2023162783A1
WO2023162783A1 PCT/JP2023/005026 JP2023005026W WO2023162783A1 WO 2023162783 A1 WO2023162783 A1 WO 2023162783A1 JP 2023005026 W JP2023005026 W JP 2023005026W WO 2023162783 A1 WO2023162783 A1 WO 2023162783A1
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cnts
elastomer composition
elastomer
fluorine
cnt
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PCT/JP2023/005026
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French (fr)
Japanese (ja)
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慶久 武山
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日本ゼオン株式会社
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C08K7/02—Fibres or whiskers
    • C08K7/04—Fibres or whiskers inorganic
    • C08K7/06—Elements
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L15/00—Compositions of rubber derivatives
    • C08L15/02—Rubber derivatives containing halogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms

Definitions

  • the present invention relates to an elastomer composition with excellent heat resistance.
  • an elastomer composition made by mixing an elastomer with a carbon material has been used as a material with excellent properties such as electrical conductivity, thermal conductivity, and strength.
  • carbon nanotubes hereinafter sometimes abbreviated as “CNT”) have attracted attention as a carbon material that is highly effective in improving the properties.
  • CNTs have excellent individual properties, they are easy to bundle due to van der Waals force when used as a bulk material due to their small outer diameter. Therefore, when producing a molded article using an elastomer composition containing an elastomer and CNTs, it is required to defibrate the CNT aggregates in which the CNTs are aggregated, and to disperse the CNTs well in the elastomer matrix. It is In the present invention, carbon nanotubes (CNT) indicate that a plurality of carbon nanotubes are included.
  • fluorine-containing elastomers have properties that can provide crosslinked articles with excellent heat resistance, chemical resistance, weather resistance, etc., so they are used in various fields such as automobiles, industrial machinery, OA equipment, and electrical and electronic equipment.
  • Patent Document 1 discloses that an elastomer composition containing a copolymer having a unit based on perfluoro(alkyl vinyl ether) as a fluorine-containing elastomer and CNTs exhibits rubber performance even at high temperatures.
  • Patent Document 2 a CNT dispersion obtained by dispersing CNT aggregates in a dispersion medium using a wet jet mill is mixed with a fluorine-containing elastomer, dried, and then a cross-linking agent is further added. It is disclosed that the elastomer composition obtained by cross-linking is excellent in heat resistance.
  • the elastomer composition is heated at 280° C. or the thermal decomposition temperature of the elastomer ⁇ 50° C., whichever is lower, for 10 minutes, and then measured by electron spin resonance method. Furthermore, it is disclosed that the value obtained by dividing by the radical concentration measured again 10 minutes after returning to normal temperature is 0.8 or more.
  • an elastomer composition containing a fluorine-containing elastomer and carbon nanotubes is required to have heat resistance that can withstand use at even higher temperatures exceeding 300° C., for example.
  • the elastomer compositions of the prior art have room for improvement in heat resistance.
  • an object of the present invention is to provide an elastomer composition having excellent heat resistance.
  • the inventor of the present invention conducted intensive studies with the aim of solving the above problems. Then, the present inventors have found that the elastomer composition containing a fluorine-containing elastomer and CNTs is heated at 370° C. for 2 hours, and then the radical concentration measured by the electron spin resonance method becomes a predetermined value or more. The inventors have found that the heat resistance of the elastomer composition can be improved by adjusting the ratio to , and completed the present invention.
  • an object of the present invention is to advantageously solve the above problems, and the present invention provides the following elastomer compositions [1] to [6].
  • the radical concentration of the elastomer composition can be measured using the method described in the examples of the present specification.
  • the elastomer composition according to any one of [1] to [3] above, wherein the carbon nanotube has a BET specific surface area of 600 m 2 /g or more.
  • the heat resistance of the elastomer composition can be further improved by using carbon nanotubes having a BET specific surface area equal to or greater than the predetermined value.
  • the "BET specific surface area” refers to the nitrogen adsorption specific surface area measured using the BET method.
  • an elastomer composition having excellent heat resistance can be provided.
  • the elastomer composition of the present invention is an elastomer composition containing a fluorine-containing elastomer and carbon nanotubes, and after being heated at 370° C. for 2 hours, the radical concentration measured by the electron spin resonance method is equal to or higher than a predetermined value. Characterized by The elastomer composition of the present invention has a radical concentration of a predetermined value or more after being heated at 370° C. for 2 hours, and thus has excellent heat resistance. In particular, the elastomer composition of the present invention can be used satisfactorily even at extremely high temperatures exceeding 300°C.
  • the elastomer composition of the present invention may further contain a cross-linking agent and additives in addition to the fluorine-containing elastomer and carbon nanotubes.
  • the elastomer composition of the present invention must have a radical concentration of 3 ⁇ 10 ⁇ 7 mol/g or more measured by an electron spin resonance method after heating at 370° C. for 2 hours, and 3.5 ⁇ 10 ⁇ It is preferably 7 mol/g or more, more preferably 4 ⁇ 10 ⁇ 7 mol/g or more, still more preferably 5 ⁇ 10 ⁇ 7 mol/g or more, and 6 ⁇ 10 ⁇ 7 mol/g or more. g or more, and even more preferably 7 ⁇ 10 ⁇ 7 mol/g or more.
  • the lower limit of the radical concentration of the elastomer composition is 3 ⁇ 10 ⁇ 7 mol/g or more, the heat resistance of the elastomer composition can be sufficiently improved.
  • the radical concentration measured above is the concentration of radicals stable at room temperature. is detected as a stable radical in the above measurement.
  • the ability of CNTs to capture the fluorine-containing elastomer-derived radicals generated by heating as stable radicals is sometimes referred to as "the ability of CNTs to capture radicals.”
  • the upper limit of the radical concentration of the elastomer composition of the present invention is not particularly limited, but is, for example, 1 ⁇ 10 ⁇ 5 mol/g or less.
  • the radical concentration of the elastomer composition can be controlled by the type of fluorine-containing elastomer, the properties of CNT (for example, carbon purity, number of layers, specific surface area, etc.) and content.
  • the radical concentration of the elastomer composition can be controlled by the state of fibrillation and dispersion of CNTs in the elastomer composition.
  • the state of fibrillation and dispersion of the CNTs in the elastomer composition can be controlled by the conditions in the method for producing the elastomer composition described below, particularly the conditions of the dispersion treatment in the dispersion step.
  • fluorine-containing elastomer Known fluororubbers can be used as the fluorine-containing elastomer without any particular limitation.
  • fluorine-containing elastomers include vinylidene fluoride rubber (FKM), tetrafluoroethylene-propylene rubber (FEPM), and tetrafluoroethylene-perfluoroalkyl vinyl ether rubber as perfluoroelastomers. (FFKM), tetrafluoroethylene rubber (TFE), and the like. These may be used individually by 1 type, and may use 2 or more types together.
  • the vinylidene fluoride rubber is a fluororubber that has vinylidene fluoride as its main component and is excellent in heat resistance, oil resistance, chemical resistance, solvent resistance, workability, and the like.
  • FKM include, but are not limited to, a binary copolymer of vinylidene fluoride and hexafluoropropylene, a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, and vinylidene fluoride. and hexafluoropropylene, tetrafluoroethylene, and vulcanization site monomers.
  • quaternary copolymer composed of vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene and a vulcanization site monomer is preferred.
  • the quaternary copolymer is available, for example, as a commercial product "Viton GBL-200S” (manufactured by Chemours Co., Ltd.).
  • "mainly composed of vinylidene fluoride” means that the vinylidene fluoride unit contained in the vinylidene fluoride rubber is 50% by mass or more, preferably more than 50% by mass.
  • Tetrafluoroethylene-propylene rubber is a fluororubber based on an alternating copolymer of tetrafluoroethylene and propylene, and has excellent heat resistance, chemical resistance, polar solvent resistance, steam resistance, etc. .
  • FEPM include, but are not limited to, a binary copolymer of tetrafluoroethylene and propylene, a terpolymer of tetrafluoroethylene, propylene and vinylidene fluoride, and crosslinked with tetrafluoroethylene and propylene.
  • Examples of commercially available binary copolymers of tetrafluoroethylene and propylene include “AFRAS (registered trademark) 100" and “AFRAS 150” manufactured by AGC Corporation.
  • Commercially available terpolymers composed of tetrafluoroethylene, propylene and vinylidene fluoride include, for example, "AFRAS 200" manufactured by AGC Corporation.
  • Commercially available terpolymers composed of tetrafluoroethylene, propylene, and cross-linking monomers include, for example, "AFRAS 300" manufactured by AGC Corporation.
  • FFKM Polytetrafluoroethylene-perfluoroalkyl vinyl ether rubber
  • H hydrogen atoms
  • C main chain carbon
  • C main chain carbon
  • FFKM can include a copolymer containing structural units derived from tetrafluoroethylene (TFE) and structural units derived from perfluoroalkyl vinyl ether (PAVE) or perfluoroalkoxyalkyl vinyl ether (PAOVE).
  • FFKM may further contain a structural unit having a cross-linking site in addition to the above two structural units.
  • Perfluoroalkyl vinyl ethers having alkyl groups of 1 to 5 carbon atoms can be used.
  • perfluoromethyl vinyl ether PMVE
  • perfluoroethyl vinyl ether PEVE
  • perfluoropropyl vinyl ether PPVE
  • n is an integer of 1 to 5, for example
  • m is an integer of 1 to 3, for example.
  • FFKM examples include AGC Corporation's "Afras (registered trademark) PM1100", “Afras PM3000” and “Afras PM4000", DuPont's “Kalrez (registered trademark)” series, Daikin Industries, Ltd. (trademark) Perflo” series, Solvay's “Technoflon (registered trademark) PFR” series, and 3M Company's “Dynion (registered trademark)” series.
  • FFKM tetrafluoroethylene-perfluoroalkyl vinyl ether rubber
  • Carbon nanotube for example, those of the first aspect and the second aspect, which will be described later, can be used.
  • the CNTs may be disentangled one by one, or may be configured as a carbon nanotube aggregate in which a plurality of CNTs are formed into a bundle.
  • CNTs according to the first aspect include the following.
  • the type of CNT is not particularly limited, and includes single-walled carbon nanotubes (sometimes abbreviated as “SWCNT”) and multi-walled carbon nanotubes (sometimes abbreviated as “MWCNT”).
  • the plurality of CNTs preferably mainly contain carbon nanotubes having from a single wall to five walls, and more preferably mainly contain single-walled carbon nanotubes.
  • the radical scavenging ability of the CNTs is enhanced, the heat resistance of the elastomer composition is further improved, and even if the amount is small, the elastomer composition can be improved. This is because the properties (for example, electrical conductivity, thermal conductivity, strength, etc.) are improved.
  • the above-mentioned "mainly including” means including more than half of the total number of the plurality of carbon nanotubes.
  • the average diameter of CNTs is preferably 1 nm or more, preferably 60 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. If the average diameter of the CNTs is within the above-specified range, the properties of the elastomer composition (eg electrical conductivity, thermal conductivity, strength, etc.) can be improved.
  • the "average diameter" of CNTs is obtained by measuring the diameter (outer diameter) of, for example, 20 CNTs on a transmission electron microscope (TEM) image and calculating the number average value. can ask.
  • the ratio (3 ⁇ /Av) of the value (3 ⁇ ) obtained by multiplying the standard deviation of the diameter ( ⁇ : sample standard deviation) by 3 to the average diameter (Av) is CNT having a ratio (3 ⁇ /Av) of more than 0.20 and less than 0.80.
  • CNTs with 3 ⁇ /Av greater than 0.25 are more preferable, and CNTs with 3 ⁇ /Av greater than 0.50 are even more preferable.
  • the properties of the elastomer composition eg electrical conductivity, thermal conductivity, strength, etc.
  • the average diameter (Av) and standard deviation ( ⁇ ) of CNTs may be adjusted by changing the CNT manufacturing method or manufacturing conditions, or by combining multiple types of CNTs obtained by different manufacturing methods. You may
  • the diameter measured as described above is plotted on the horizontal axis and the frequency is plotted on the vertical axis, and when Gaussian approximation is performed, a normal distribution is usually used.
  • the average length of CNTs is preferably 10 ⁇ m or more, more preferably 50 ⁇ m or more, still more preferably 80 ⁇ m or more, preferably 600 ⁇ m or less, and more preferably 550 ⁇ m or less. , 500 ⁇ m or less. If the average length of the CNTs is within the predetermined range, the properties of the elastomer composition (eg electrical conductivity, thermal conductivity, strength, etc.) can be improved. In the present invention, the "average length" of CNTs can be obtained by measuring the length of, for example, 20 CNTs on a scanning electron microscope (SEM) image and calculating the number average value. can.
  • SEM scanning electron microscope
  • CNTs usually have an aspect ratio of more than 10.
  • the aspect ratio of CNTs is determined by measuring the diameter and length of 20 randomly selected CNTs using a scanning electron microscope or transmission electron microscope, and measuring the ratio of the diameter to the length (length/diameter). It can be obtained by calculating the average value.
  • the CNT preferably has a BET specific surface area of 600 m 2 /g or more, more preferably 800 m 2 /g or more, preferably 2000 m 2 /g or less, and 1800 m 2 /g or less. is more preferable, and 1600 m 2 /g or less is even more preferable. If the BET specific surface area of the CNTs is 600 m 2 /g or more, the radical scavenging ability of the CNTs is enhanced, the heat resistance of the elastomer composition is further improved, and properties of the elastomer composition (e.g., conductivity , thermal conductivity, strength, etc.). Further, when the BET specific surface area of CNT is 2000 m 2 /g or less, the CNT bundle structure can be defibrated satisfactorily.
  • the t-plot obtained from the adsorption isotherm preferably shows an upward convex shape.
  • the "t-plot" can be obtained by converting the relative pressure to the average thickness t (nm) of the nitrogen gas adsorption layer in the CNT adsorption isotherm measured by the nitrogen gas adsorption method. That is, the conversion is performed by obtaining the average thickness t of the nitrogen gas adsorption layer corresponding to the relative pressure from a known standard isotherm obtained by plotting the average thickness t of the nitrogen gas adsorption layer against the relative pressure P/P0. gives a t-plot of CNTs (t-plot method by de Boer et al.). It should be noted that CNTs exhibiting a convex shape in the t-plot obtained from the adsorption isotherm are preferably CNTs that have not undergone opening treatment.
  • the growth of a nitrogen gas adsorption layer on a substance having pores on its surface is classified into the following processes (1) to (3). Then, the slope of the t-plot changes due to the following processes (1) to (3).
  • the t-plot showing an upwardly convex shape is located on a straight line passing through the origin in a region where the average thickness t of the nitrogen gas adsorption layer is small, whereas when t increases, the plot moves downward from the straight line.
  • position shifted to A CNT having such a t-plot shape has a large ratio of internal specific surface area to the total specific surface area of the CNT, indicating that a large number of openings are formed in the carbon nanostructure constituting the CNT.
  • the inflection point of the t-plot of CNT is preferably in the range that satisfies 0.2 ⁇ t (nm) ⁇ 1.5, and is in the range of 0.45 ⁇ t (nm) ⁇ 1.5. is more preferable, and it is even more preferable to be in the range of 0.55 ⁇ t(nm) ⁇ 1.0. If the inflection point of the t-plot of CNT is within such a range, it is possible to enhance the properties (eg electrical conductivity, thermal conductivity, strength, etc.) of the elastomer composition with a small amount.
  • the "position of the bending point" is the intersection of the approximate straight line A in the process (1) described above and the approximate straight line B in the process (3) described above.
  • the measurement of the adsorption isotherm of CNT, the creation of the t-plot, and the calculation of the total specific surface area S1 and the internal specific surface area S2 based on the analysis of the t-plot can be performed, for example, by a commercially available measurement device "BELSORP ( (registered trademark)-mini” (manufactured by Nippon Bell Co., Ltd.).
  • the CNT preferably has a Radial Breathing Mode (RBM) peak when evaluated using Raman spectroscopy.
  • RBM Radial Breathing Mode
  • RBM does not exist in the Raman spectrum of multilayer CNTs having three or more layers.
  • the ratio of the G band peak intensity to the D band peak intensity (G/D ratio) in the Raman spectrum of the CNT is preferably 0.5 or more and 5.0 or less, and can be 1.0 or more. It may be 4.0 or less. If the G/D ratio is 0.5 or more and 5.0 or less, the properties (eg electrical conductivity, thermal conductivity, strength, etc.) of the elastomer composition can be improved.
  • the carbon purity of CNT is preferably 90% by mass, more preferably 94% by mass or more, still more preferably 96% by mass or more, even more preferably 98% by mass or more, and 99% by mass. % or more is even more preferable. If the carbon purity of the CNTs is equal to or higher than the above lower limit, the radical scavenging ability of the CNTs can be enhanced, and the heat resistance of the elastomer composition can be further improved. Although the upper limit of the carbon purity of CNT is not particularly limited, it is, for example, 99.9999% by mass or less.
  • CNTs can be produced using known CNT synthesis methods such as an arc discharge method, a laser ablation method, and a chemical vapor deposition method (CVD method), without being particularly limited.
  • CNTs are synthesized, for example, by supplying a raw material compound and a carrier gas onto a substrate having a catalyst layer for CNT production on its surface, and synthesizing CNTs by chemical vapor deposition (CVD).
  • CVD chemical vapor deposition
  • CNT obtained by the super-growth method may be referred to as "SGCNT”.
  • CNTs produced by the super-growth method may consist of SGCNTs only, or may contain other carbon nanostructures such as non-cylindrical carbon nanostructures in addition to SGCNTs.
  • CNTs according to the second aspect include the following.
  • a CNT aggregate composed of CNTs according to the second aspect satisfies at least one of the following conditions (1) to (3) and is excellent in dispersibility in a matrix (fluorine-containing elastomer in the present invention).
  • ⁇ Condition (2) The maximum peak in the differential pore volume distribution measured for the aggregate of carbon nanotubes is in the range of pore diameters of more than 100 nm and less than 400 nm.
  • ⁇ Condition (3) At least one peak of the two-dimensional spatial frequency spectrum of the electron microscope image of the aggregate of carbon nanotubes exists in the range of 1 ⁇ m -1 to 100 ⁇ m -1 .
  • the CNT aggregate satisfying at least one of the conditions (1) to (3) is excellent in dispersibility is not clear, but is presumed to be as follows. That is, the CNTs constituting the CNT aggregate that satisfies at least one of the conditions (1) to (3) have a wavy structure. It is speculated that due to such a "wavy structure", interaction between CNTs constituting the CNT aggregate can be suppressed. If the interaction between CNTs is suppressed, it is possible to suppress the strong bundling and agglomeration of the CNTs contained in the CNT aggregate. This can make it possible to easily disperse the CNT aggregates. Furthermore, if the CNT aggregates can be easily dispersed, there is an effect that the easiness of secondary processing of such CNT aggregates is improved.
  • the wave number is in the range of more than 300 cm -1 and 2000 cm -1 or less, preferably in the wave number range of 500 cm -1 or more and 2000 cm -1 or less, more preferably in the wave number range of 700 cm -1 or more and 2000 cm -1 or less, If a peak based on plasmon resonance of CNTs is present, such CNTs can exhibit good dispersibility.
  • condition (1) in acquiring a spectrum by Fourier transform infrared spectroscopy, it is necessary to obtain a carbon nanotube dispersion by dispersing the aggregate of carbon nanotubes so that the bundle length is 10 ⁇ m or more.
  • a carbon nanotube aggregate, water, and a surfactant for example, sodium dodecylbenzenesulfonate
  • a surfactant for example, sodium dodecylbenzenesulfonate
  • the bundle length of the carbon nanotube dispersion can be obtained by analyzing it with a wet image analysis type particle size measuring device. Such a measurement device calculates the area of each dispersion from the image obtained by photographing the carbon nanotube dispersion, and the diameter of the circle having the calculated area (hereinafter also referred to as ISO area diameter) can be obtained).
  • ISO area diameter the diameter of the circle having the calculated area
  • the bundle length of each dispersion is defined as the value of the ISO circle diameter thus obtained.
  • the differential pore volume distribution of the aggregate of carbon nanotubes can be obtained from the adsorption isotherm of liquid nitrogen at 77K based on the BJH (Barrett-Joyner-Halenda) method.
  • the BJH method is a measurement method for determining the pore size distribution assuming that the pores are cylindrical.
  • the fact that the peak in the differential pore volume distribution measured for the carbon nanotube aggregate is in the range of more than 100 nm means that the carbon nanotube aggregate has voids of a certain size between the CNTs and the CNTs are excessively overcrowded. It means that it is not in an aggregated state.
  • the upper limit of 400 nm is the measurement limit of the measuring device (BELSORP-mini II) used in the examples.
  • the value of the differential pore volume at the maximum peak in the differential pore volume distribution of the CNT aggregate is preferably 2 cm 3 /g or more.
  • the sufficiency of such conditions can be determined in the following manner.
  • the CNT aggregate to be determined is magnified (e.g., 10,000 times) using an electron microscope (e.g., field emission scanning electron microscope), and a plurality of electron microscope images ( For example, 10 sheets) are acquired.
  • a plurality of electron microscope images obtained are subjected to fast Fourier transform (FFT) processing to obtain a two-dimensional spatial frequency spectrum.
  • FFT fast Fourier transform
  • a two-dimensional spatial frequency spectrum obtained for each of a plurality of electron microscope images is binarized to obtain an average value of peak positions appearing on the highest frequency side. When the average value of the obtained peak positions was within the range of 1 ⁇ m ⁇ 1 or more and 100 ⁇ m ⁇ 1 or less, it was determined that the condition (3) was satisfied.
  • the peak of the two-dimensional spatial frequency spectrum exists in the range of 2.6 ⁇ m ⁇ 1 or more and 100 ⁇ m ⁇ 1 or less.
  • the aggregate of carbon nanotubes of the present invention preferably satisfies at least two of the conditions (1) to (3), and satisfies all the conditions (1) to (3). It is more preferable to satisfy
  • the CNT aggregate according to the second aspect preferably has, for example, the following properties.
  • the CNT aggregate preferably has a total specific surface area of 600 m 2 /g or more, more preferably 800 m 2 /g or more, and preferably 2600 m 2 /g or less, more preferably 1400 m 2 /g or less, as determined by the BET method. . Furthermore, it is preferable that the surface area is 1,300 m 2 /g or more for those subjected to the opening treatment.
  • a CNT aggregate having a high specific surface area has gaps between CNTs constituting the aggregate, and the CNTs are not excessively bundled.
  • the CNT aggregate is mainly composed of single-walled CNTs, and may include double-walled CNTs and multi-walled CNTs to the extent that the functions are not impaired.
  • the average height of the CNTs constituting the CNT aggregate from the carrier surface is preferably 10 ⁇ m or more and 10 cm or less, and 100 ⁇ m or more. It is more preferably 2 cm or less.
  • the average height of the CNTs constituting the CNT aggregate is 10 ⁇ m or more, aggregation with adjacent CNT bundles can be prevented and the CNTs can be easily dispersed. If the average height of the CNTs constituting the CNT aggregate is 100 ⁇ m or more, it becomes easy to form a network between CNTs, and the CNTs can be suitably used in applications requiring electrical conductivity or mechanical strength.
  • the average height of the CNTs forming the CNT aggregate is 10 cm or less, the formation can be performed in a short time, so that the adhesion of carbon-based impurities can be suppressed and the specific surface area can be improved. If the average height of the CNTs constituting the CNT aggregate is 2 cm or less, the CNTs can be dispersed more easily.
  • the average height of CNTs can be obtained by measuring the height of 100 randomly selected CNTs using a scanning electron microscope (SEM).
  • the tap bulk density of the CNT aggregate is preferably 0.001 g/cm 3 or more and 0.2 g/cm 3 or less.
  • a CNT aggregate having such a density range does not excessively strengthen the bonds between CNTs, so that it is excellent in dispersibility and can be molded into various shapes. If the tapped bulk density of the CNT aggregate is 0.2 g/cm 3 or less, the bonds between the CNTs become weak, so that when the CNT aggregate is stirred in a solvent or the like, it becomes easy to uniformly disperse it. Further, when the tap bulk density of the CNT aggregate is 0.001 g/cm 3 or more, the integrity of the CNT aggregate is improved and handling is facilitated.
  • the tapped bulk density is the apparent bulk density in a state in which the powdery CNT aggregates are filled in a container, and then the gaps between the powder particles are reduced by tapping or vibration to close-pack.
  • the average diameter of the CNTs constituting the CNT aggregate is preferably 0.5 nm or more, more preferably 1.0 nm or more, preferably 15.0 nm or less, and preferably 10.0 nm or less. It is more preferable to have a thickness of 5.0 nm or less. If the average diameter of CNTs is 1.0 nm or more, bundling of CNTs can be reduced and a high specific surface area can be maintained. If the average diameter of CNTs is 5.0 nm or less, the multilayer CNT ratio can be reduced and a high specific surface area can be maintained.
  • the average diameter of CNTs constituting the CNT aggregate can be obtained by measuring the diameter (outer diameter) of 100 randomly selected CNTs using a transmission electron microscope (TEM).
  • the average diameter of CNTs may be adjusted by changing the production method and production conditions of CNTs, or by combining multiple types of CNTs obtained by different production methods.
  • the G/D ratio of the CNT aggregate is preferably 1 or more and 50 or less.
  • a CNT aggregate with a G/D ratio of less than 1 is considered to have low crystallinity of single-walled CNTs, a large amount of dirt such as amorphous carbon, and a large content of multi-walled CNTs.
  • CNT aggregates with a G/D ratio of more than 50 have high linearity, CNTs tend to form bundles with few gaps, and the specific surface area may decrease.
  • the G/D ratio is an index commonly used to evaluate the quality of CNTs.
  • G band Near 1600 cm ⁇ 1
  • D band Near 1350 cm ⁇ 1
  • G band Vibrational modes called G band (near 1600 cm ⁇ 1 ) and D band (near 1350 cm ⁇ 1 ) are observed in the Raman spectrum of CNTs measured by a Raman spectrometer.
  • the G band is a vibrational mode derived from the hexagonal lattice structure of graphite, which is the cylindrical surface of CNT
  • the D band is a vibrational mode derived from amorphous sites. Therefore, a CNT with a higher peak intensity ratio (G/D ratio) between the G band and the D band can be evaluated as having higher crystallinity (linearity).
  • the carbon purity of the CNT aggregate is preferably 90% by mass, more preferably 94% by mass or more, still more preferably 96% by mass or more, even more preferably 98% by mass or more, More preferably, it is 99% by mass or more. If the carbon purity of the CNT aggregates is equal to or higher than the above lower limit, the radical scavenging ability of the CNT aggregates can be enhanced, and the heat resistance of the elastomer composition can be further improved. Although the upper limit of the carbon purity of CNT is not particularly limited, it is, for example, 99.9999% by mass or less.
  • the carbon nanotube aggregate according to the second aspect can be produced using a CNT synthesis process according to known methods such as the fluidized bed method, moving bed method and fixed bed method.
  • the fluidized bed method means a synthesis method for synthesizing CNTs while fluidizing a granular carrier supporting a catalyst for synthesizing CNTs (hereinafter also referred to as a granular catalyst carrier).
  • the moving bed method and the fixed bed method mean synthesis methods for synthesizing CNTs without fluidizing a carrier (particulate carrier or plate-shaped carrier) supporting a catalyst.
  • the content of CNTs in the elastomer composition of the present invention is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, with respect to 100 parts by mass of the fluorine-containing elastomer. More preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, preferably 10 parts by mass or less, 8 parts by mass or less is more preferably 6 parts by mass or less, even more preferably 5 parts by mass or less, and even more preferably 4 parts by mass or less.
  • the heat resistance of the elastomer composition can be further improved by good dispersion of the CNTs in the elastomer composition.
  • CNT a single wall CNT (SWCNT) and a multilayer CNT (MWCNT) can be used together.
  • SWCNT single wall CNT
  • MWCNT multilayer CNT
  • the content of CNTs in the above elastomer composition means the total content of single-walled CNTs and multi-walled CNTs.
  • the content of the single-walled CNTs in the elastomer composition is preferably 0.1 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the fluorine-containing elastomer. Furthermore, when the CNTs are multilayer CNTs, the content of the multilayer CNTs in the elastomer composition is preferably 0.5 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the fluorine-containing elastomer.
  • the elastomeric composition of the invention may optionally further comprise a cross-linking agent. That is, the elastomer composition of the present invention may be a crosslinkable composition further comprising a crosslinking agent in addition to the (uncrosslinked) fluorine-containing elastomer and CNTs described above.
  • the cross-linking agent that can be contained in the elastomer composition is not particularly limited, but any known cross-linking agent capable of cross-linking the fluorine-containing elastomer in the elastomer composition can be used.
  • cross-linking agents examples include peroxide-based cross-linking agents, bisphenol-based cross-linking agents, diamine-based cross-linking agents, triazine-based cross-linking agents, oxazole-based cross-linking agents, imidazole-based cross-linking agents, and thiazole-based cross-linking agents.
  • a crosslinking agent can be used individually by 1 type or in mixture of 2 or more types.
  • the content of the cross-linking agent in the elastomer composition is not particularly limited, and may be the amount normally used in known elastomer compositions.
  • the fluorine-containing elastomer in the elastomer composition of the present invention may be cross-linked by the cross-linking agent. That is, the elastomer composition of the present invention may be a cross-linked product obtained by cross-linking a cross-linkable pre-composition containing at least the fluorine-containing elastomer, CNTs and a cross-linking agent.
  • Additives that may be included in the elastomer composition include, but are not limited to, dispersants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, pigments, colorants, foaming agents, antistatic agents, Flame retardants, lubricants, softeners, tackifiers, plasticizers, release agents, deodorants, perfumes, and the like can be mentioned.
  • Examples of more specific additives include carbon black, silica, talc, barium sulfate, calcium carbonate, clay, magnesium oxide and calcium hydroxide.
  • an additive can be used individually by 1 type or in mixture of 2 or more types.
  • the content of the additive in the elastomer composition is not particularly limited, and may be the amount normally used in known elastomer compositions.
  • the method for producing the elastomer composition of the present invention is not particularly limited.
  • An example of the method for producing the elastomer composition of the present invention includes a dispersing step of obtaining a carbon nanotube dispersion by mixing and dispersing a fluorine-containing elastomer, carbon nanotubes, and a solvent capable of dissolving the fluorine-containing elastomer, and and a drying step of removing the solvent from the carbon nanotube dispersion to obtain a dried product.
  • An example of the method for producing the elastomer composition of the present invention is a kneading step in which a cross-linking agent, an additive, etc.
  • the method for producing the elastomer composition of the present invention may further include a molding step of obtaining a molded article in which the shape of the crosslinked product as the elastomer composition is fixed.
  • the fluorine-containing elastomer, carbon nanotubes, and a solvent capable of dissolving the fluorine-containing elastomer are mixed and dispersed to obtain a carbon nanotube dispersion.
  • the resulting carbon nanotube dispersion contains an elastomer solution in which a fluorine-containing elastomer is dissolved in a solvent, and carbon nanotubes (or aggregates of carbon nanotubes) dispersed in the elastomer solution.
  • the solvent is not particularly limited as long as it can dissolve the fluorine-containing elastomer.
  • solvents include ketones such as methyl ethyl ketone and acetone, ethers such as tetrahydrofuran, and fluorine-based solvents. Among these, fluorine-based solvents are preferred.
  • a solvent having a perfluorohydrocarbon group can be used as the fluorine-based solvent.
  • the perfluorohydrocarbon group may be a chain perfluorohydrocarbon group or a cyclic perfluorohydrocarbon group.
  • the chain-type perfluorohydrocarbon group may be linear or branched.
  • chain perfluorohydrocarbon groups include perfluoroalkyl groups, perfluoroalkylene groups, perfluorovinylalkyl groups, and perfluorovinylalkylene groups.
  • the perfluorohydrocarbon group having the largest number of carbon atoms in the perfluorohydrocarbon group has 3 to 7 carbon atoms. When the number of carbon atoms is 3 or more, the solubility of the fluorine-containing elastomer in fluorine-based solvents is excellent. When the number of carbon atoms is 7 or less, the fluorine-based solvent is easily available. Further, when the number of carbon atoms is 6 or less, the boiling point of the fluorine-based solvent tends to be low, making it easy to remove.
  • the boiling point of the fluorinated solvent is preferably 50 to 160°C.
  • the boiling point of the fluorine-based solvent is 50° C. or higher, the dispersion treatment can be stably performed. If the boiling point of the fluorine-based solvent is 160° C. or lower, the fluorine-based solvent can be easily removed.
  • At least one selected from the group consisting of fluorine-containing compounds having a nitrogen atom, hydrofluorocarbons, and hydrofluoroethers is preferable as the fluorine-based solvent.
  • the fluorine-containing solvent is at least one selected from the group consisting of nitrogen-containing fluorine-containing compounds, hydrofluorocarbons, and hydrofluoroethers
  • the fluorine-containing elastomer tends to have excellent solubility in the fluorine-containing solvent.
  • a solvent may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.
  • fluorinated solvent having a nitrogen atom is Fluorinert (registered trademark) FC-770 manufactured by 3M Company.
  • hydrofluorocarbons include 1,1,1,2,2,3,3,4,4-nonafluorohexane, 1,1,1,2,2,3,3,4,4,5, Examples include 5,6,6-tridecafluorohexane and 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane.
  • Commercial products of 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane include Asahiklin (registered trademark) AC-2000, 1 manufactured by AGC.
  • 1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane is exemplified by Asahiklin (registered trademark) AC-6000 manufactured by AGC. be.
  • hydrofluoroethers include Novec (registered trademark) 7300 manufactured by 3M.
  • the dispersing step includes, for example, a dissolving step of dissolving the fluorine-containing elastomer in a solvent to obtain an elastomer solution, and a dispersing step of mixing carbon nanotubes in the obtained elastomer solution and dispersing the carbon nanotubes.
  • the dissolution step may be performed by dissolving the fluorine-containing elastomer in a solvent, and can be performed by a known method.
  • the dispersion treatment step may be any known dispersion treatment as long as the CNTs can be dispersed in the elastomer solution. Examples of such dispersion treatment include dispersion treatment by shear stress, dispersion treatment by collision energy, and dispersion treatment that produces a cavitation effect. According to such distributed processing, distributed processing can be performed relatively easily.
  • Devices that can be used for dispersion treatment using shear stress include a two-roll mill and a three-roll mill.
  • Apparatuses that can be used for dispersion treatment by collision energy include bead mills, rotor/stator type dispersers, and the like.
  • a jet mill, an ultrasonic disperser, and the like can be used as devices that can be used for the dispersion treatment to obtain the cavitation effect.
  • the conditions for the dispersion treatment are not particularly limited, and can be appropriately set within the range of normal dispersion conditions in the apparatus described above, for example.
  • a bead mill and an ultrasonic dispersion disperser are used in combination.
  • the peripheral speed (rotational speed) of the bead mill can be adjusted as appropriate, but is preferably, for example, 4 m/s or more, more preferably 5 m/s or more, and even more preferably 6 m/s or more.
  • the peripheral speed of the bead mill is within the above-specified range, the CNTs can be dispersed more favorably in the obtained CNT dispersion, and the heat resistance of the produced elastomer composition can be further improved.
  • the solvent is removed from the CNT dispersion obtained in the dispersion step to obtain a dried product.
  • the drying step can remove the solvent from the CNT dispersion, and known methods such as coagulation, casting, and drying can be used.
  • a dried product obtained in the drying step may be used as the elastomer composition of the present invention.
  • a cross-linkable pre-composition is obtained by adding a cross-linking agent, an additive, and the like to the dried product and mixing them.
  • the kneading step can be performed using, for example, a mixer, a single-screw kneader, a twin-screw kneader, rolls, a pressure kneader, Brabender (registered trademark), an extruder, or the like.
  • the crosslinkable pre-composition obtained in the kneading step may also be used as the elastomer composition of the present invention.
  • the cross-linkable pre-composition is cross-linked to obtain a cross-linked product as an elastomer composition.
  • the press molding and the cross-linking step can be performed at the same time by putting the cross-linkable pre-composition into a mold having a desired shape and heating it.
  • the crosslinkable pre-composition is put into a mold of a desired shape and heated to simultaneously perform press molding and primary crosslinking, and then the obtained primary crosslinked product is heated again with a heating device such as a gear oven.
  • Secondary cross-linking can also be performed by heating. Conditions such as the temperature and time of the cross-linking reaction can be appropriately set.
  • a molded article is obtained in which the shape of the crosslinked product as the elastomer composition is fixed.
  • the molding step can be carried out by any method such as injection molding, extrusion molding, press molding, roll molding, and the like. Since the molded article obtained in the molding step is made of the elastomer composition of the present invention, it has excellent heat resistance. In addition, the molded article obtained in the molding process is excellent in properties such as electrical conductivity, thermal conductivity and strength because CNTs are well dispersed in the fluorine-containing elastomer.
  • Molded articles made from the elastomer composition of the present invention can be used, for example, in automobile parts, air conditioning equipment, control equipment, water supply/hot water supply equipment, high-temperature steam equipment, semiconductor equipment, food processing equipment, analytical/physical and chemical equipment, liquid storage equipment, and pressure equipment. High tensile strength and high elongation are required in a high temperature environment, used in fields such as switch devices, paint/coating equipment, printing/coating equipment, OA equipment, fuel cell peripheral equipment, oil drilling and medical fields. It can be suitably used as various parts.
  • the molded article can be used as a hose, a sealing material, a belt, an anti-vibration rubber, a diaphragm, a hollow rubber molded article, a roll, a tube, and the like.
  • the hose is not particularly limited, and examples include fuel hose, turbo air hose, oil hose, radiator hose, heater hose, water hose, vacuum brake hose, control hose, air conditioner hose, brake hose, power steering hose, air hose, Various hoses such as marine hoses, risers, and flow lines can be mentioned.
  • the sealing material is not particularly limited, and various types of seals such as O-rings, packings, oil seals, shaft seals, bearing seals, mechanical seals, well head seals, seals for electric/electronic devices, and seals for pneumatic devices can be used.
  • the belt is not particularly limited, and examples thereof include various belts such as power transmission belts and conveyor belts.
  • the vibration-isolating rubber is not particularly limited, and examples thereof include various vibration-isolating rubbers such as automotive vibration-isolating rubber.
  • the diaphragm is not particularly limited, and examples include automobile engine diaphragms such as fuel systems, exhaust systems, brake systems, drive systems, and ignition systems; pump diaphragms; valve diaphragms; filter press diaphragms; blower diaphragms; various diaphragms.
  • the hollow rubber molding is not particularly limited, and examples include various bladders such as tire manufacturing bladders and tire vulcanizing bladders; various joints such as flexible joints and expansion joints; joint boots, rack and pinion steering boots, pin boots, various boots such as a piston boot; various valves such as a primer valve;
  • the roll is not particularly limited, and examples include a printing roll; a coating roll; a copying roll such as a printer;
  • the tube is not particularly limited, and for example, tubes for analytical instruments; tubes for pumps, reactors, stirrers, and mixers; tubes for ink such as printers; tubes for pumps for semiconductor manufacturing equipment; tubes for fuel cells. a tube that requires high corrosive gas resistance; and the like.
  • thermogravimetric analyzer manufactured by TA Instruments, product name “Discovery TGA5500”
  • 2 mg of the carbon nanotubes used in Examples and Comparative Examples were heated from room temperature to 800 ° C. at a rate of 5 ° C./min in an air atmosphere. was performed, and the weight (%) that decreased due to the temperature rising up to 800° C. was obtained as the carbon purity.
  • test piece after heat aging using a tensile tester (manufactured by Toyo Seiki Co., Ltd., product name "Strograph VG", in accordance with JIS K6251: 2010, test temperature 23 ° C., test humidity 50%, tensile speed 500 mm / A tensile test was carried out under conditions of minutes, and the elongation until the test piece broke was measured. The larger the elongation value, the more excellent the heat resistance of the elastomer composition.
  • Example 1 ⁇ Dispersion process> 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)-pentane (manufactured by 3M, product name Novec (registered 100 parts (100 g) of FFKM (manufactured by AGC, trade name "Aflas PM-3000”) as a fluorine-containing elastomer is added to 1899 g of the product (trademark) 7300”), and the fluorine-containing elastomer is dissolved by stirring at a temperature of 20°C for 12 hours. to obtain a fluorine-containing elastomer solution (dissolution step).
  • SGCNTs as carbon nanotubes were added to the fluorine-containing elastomer solution.
  • the obtained slurry was mixed with a holding tank and a bead mill (manufactured by Willie & Bakkofen, trade name “Dyno Mill Multilab", zirconia beads average diameter: 0.65 mm, peripheral speed 8 m / s) and an ultrasonic disperser (Sonic Technology Co., Ltd., trade name "GSD600AT", amplitude of ultrasonic waves: 30 ⁇ m) was circulated in a circulation system with a retention time of 30 minutes to obtain a dispersion (dispersion treatment step).
  • a bead mill manufactured by Willie & Bakkofen, trade name “Dyno Mill Multilab", zirconia beads average diameter: 0.65 mm, peripheral speed 8 m / s
  • an ultrasonic disperser Sonic Technology Co., Ltd., trade name "GSD600AT", amplitude of ultrasonic waves: 30 ⁇ m
  • ⁇ Crosslinking step> The obtained crosslinkable pre-composition was put into a mold and crosslinked at a temperature of 150° C. and a pressure of 10 MPa for 20 minutes to obtain a crosslinked sheet after primary vulcanization (length: 150 mm, width: 150 mm, thickness : 2 mm). Then, heat treatment was performed for 4 hours in a gear oven (manufactured by Toyo Seiki Co., Ltd., model "S60”) at 250°C to obtain a sheet-like crosslinked product after secondary vulcanization as an elastomer composition. Using this elastomer composition, the radical concentration after heating at 370° C. for 2 hours and the elongation after heat aging were measured and evaluated. Table 1 shows the results.
  • Example 2 In the dispersion step of Example 1, MWCNT (manufactured by KUMHO PETROCHEMICAL, product name “K-nanos 100P”, BET specific surface area: 259 m 2 /g, carbon purity: 94 instead of SGCNT 2 parts (2 g) as carbon nanotubes .1%) 6 parts (6 g) was added, and the dispersion step, drying step, kneading step, and cross-linking step were carried out in the same manner as in Example 1. Using the obtained elastomer composition, Radical concentration after heating at 370° C. for 2 hours and elongation after heat aging were measured and evaluated. Table 1 shows the results.
  • Example 3 In the dispersing step of Example 1, the dispersing step, the drying, and the After the steps, kneading step and cross-linking step were performed, the obtained elastomer composition was used to measure and evaluate the radical concentration after heating at 370° C. for 2 hours and the elongation after heat aging. Table 1 shows the results.
  • Example 2 In the dispersion step of Example 1, as the dispersion treatment conditions for obtaining the dispersion liquid, the ultrasonic dispersing machine was not connected, except that a circulation system formed by connecting the holding tank and the bead mill was used. The dispersion step, drying step, kneading step, and cross-linking step were carried out in the same manner as in , and the obtained elastomer composition was used to measure the radical concentration after heating at 370 ° C. for 2 hours and the elongation after heat aging. evaluated. Table 1 shows the results.
  • an elastomer composition having excellent heat resistance can be provided.

Abstract

The purpose of the present invention is to provide an elastomer composition having excellent heat resistance. The elastomer composition of the present invention, which comprises a fluorine-containing elastomer and carbon nanotubes, is characterized in that the radical concentration measured by the electron spin resonance method after heating at 370°C for 2 hours is 3×10-7 mol/g or more.

Description

エラストマー組成物Elastomer composition
　本発明は、耐熱性に優れたエラストマー組成物に関する。 The present invention relates to an elastomer composition with excellent heat resistance.
　従来、導電性、熱伝導性、及び強度などの特性に優れる材料として、エラストマーにカーボン材料を配合してなるエラストマー組成物が使用されている。近年では、前記特性の向上効果が高いカーボン材料として、カーボンナノチューブ（以下、「ＣＮＴ」と略記する場合がある。）が注目されている。 Conventionally, an elastomer composition made by mixing an elastomer with a carbon material has been used as a material with excellent properties such as electrical conductivity, thermal conductivity, and strength. In recent years, carbon nanotubes (hereinafter sometimes abbreviated as “CNT”) have attracted attention as a carbon material that is highly effective in improving the properties.
　ＣＮＴは、一本一本の特性は優れているものの、外径が小さいため、バルク材料として使用する際にファンデルワールス力によってバンドル化し易い（束になり易い）。そのため、エラストマーとＣＮＴとを含有するエラストマー組成物を用いて成形体を作製するに際しては、ＣＮＴが凝集したＣＮＴ集合体を解繊し、エラストマーであるマトリックス中にＣＮＴを良好に分散させることが求められている。なお、本発明において、カーボンナノチューブ（ＣＮＴ）には、複数本のカーボンナノチューブが含まれていることを示す。 　Although CNTs have excellent individual properties, they are easy to bundle due to van der Waals force when used as a bulk material due to their small outer diameter. Therefore, when producing a molded article using an elastomer composition containing an elastomer and CNTs, it is required to defibrate the CNT aggregates in which the CNTs are aggregated, and to disperse the CNTs well in the elastomer matrix. It is In the present invention, carbon nanotubes (CNT) indicate that a plurality of carbon nanotubes are included.
　他方、フッ素含有エラストマーは、耐熱性、耐薬品性、耐候性等に優れた架橋物品を提供できる特性を有しているため、自動車、産業機械、ＯＡ機器、電気電子機器等の各種分野で使用されている。例えば、特許文献１には、フッ素含有エラストマーとしてのパーフルオロ（アルキルビニルエーテル）に基づく単位を有する共重合体と、ＣＮＴとを含有するエラストマー組成物であれば、高温下に置かれてもゴム性能の低下を抑えることができる旨開示されている。また、特許文献２には、湿式ジェットミルを用いて分散媒中にＣＮＴ集合体を分散させて得られたＣＮＴ分散液と、フッ素含有エラストマーとを混合し、乾燥した後、架橋剤を更に添加して架橋して得られたエラストマー組成物が、耐熱性に優れている旨が開示されている。特許文献２には、当該エラストマー組成物を、２８０℃、または当該エラストマーの熱分解温度－５０℃のいずれか低い温度で１０分間加熱した後に電子スピン共鳴法により測定したラジカル濃度を、当該加熱後さらに常温に戻して１０分後に再度測定したラジカル濃度で割って得られる値が０．８以上である旨が開示されている。 On the other hand, fluorine-containing elastomers have properties that can provide crosslinked articles with excellent heat resistance, chemical resistance, weather resistance, etc., so they are used in various fields such as automobiles, industrial machinery, OA equipment, and electrical and electronic equipment. It is For example, Patent Document 1 discloses that an elastomer composition containing a copolymer having a unit based on perfluoro(alkyl vinyl ether) as a fluorine-containing elastomer and CNTs exhibits rubber performance even at high temperatures. It is disclosed that it is possible to suppress the decrease in Further, in Patent Document 2, a CNT dispersion obtained by dispersing CNT aggregates in a dispersion medium using a wet jet mill is mixed with a fluorine-containing elastomer, dried, and then a cross-linking agent is further added. It is disclosed that the elastomer composition obtained by cross-linking is excellent in heat resistance. In Patent Document 2, the elastomer composition is heated at 280° C. or the thermal decomposition temperature of the elastomer −50° C., whichever is lower, for 10 minutes, and then measured by electron spin resonance method. Furthermore, it is disclosed that the value obtained by dividing by the radical concentration measured again 10 minutes after returning to normal temperature is 0.8 or more.
特開２０１９－１８９７０２号公報JP 2019-189702 A 国際公開第２０１６／１３３２０１号WO2016/133201
　ここで、フッ素含有エラストマーとカーボンナノチューブとを含むエラストマー組成物は、例えば３００℃を超える更なる高温下での使用に耐え得る耐熱性が求められている。
　しかしながら、上記従来技術のエラストマー組成物は、耐熱性に改善の余地があった。 Here, an elastomer composition containing a fluorine-containing elastomer and carbon nanotubes is required to have heat resistance that can withstand use at even higher temperatures exceeding 300° C., for example.
However, the elastomer compositions of the prior art have room for improvement in heat resistance.
　そこで、本発明は、耐熱性に優れたエラストマー組成物を提供することを目的とする。 Therefore, an object of the present invention is to provide an elastomer composition having excellent heat resistance.
　本発明者は、上記課題を解決することを目的として鋭意検討を行った。そして、本発明者は、フッ素含有エラストマーとＣＮＴとを含むエラストマー組成物について、当該エラストマー組成物を３７０℃で２時間加熱した後に電子スピン共鳴法により測定されるラジカル濃度が所定値以上になるように調整すれば、当該エラストマー組成物の耐熱性が向上することを見出し、本発明を完成させた。 The inventor of the present invention conducted intensive studies with the aim of solving the above problems. Then, the present inventors have found that the elastomer composition containing a fluorine-containing elastomer and CNTs is heated at 370° C. for 2 hours, and then the radical concentration measured by the electron spin resonance method becomes a predetermined value or more. The inventors have found that the heat resistance of the elastomer composition can be improved by adjusting the ratio to , and completed the present invention.
　即ち、この発明は、上記課題を有利に解決することを目的とするものであり、本発明によれば、以下の〔１〕～〔６〕のエラストマー組成物が提供される。 That is, an object of the present invention is to advantageously solve the above problems, and the present invention provides the following elastomer compositions [1] to [6].
〔１〕フッ素含有エラストマーと、カーボンナノチューブとを含むエラストマー組成物であって、３７０℃で２時間加熱後に電子スピン共鳴法により測定されるラジカル濃度が３×１０－７ｍｏｌ／ｇ以上である、エラストマー組成物。
　なお、エラストマー組成物の上記ラジカル濃度は、本明細書の実施例に記載の方法を用いて測定することができる。 [1] An elastomer composition containing a fluorine-containing elastomer and carbon nanotubes, having a radical concentration of 3×10 −7 mol/g or more as measured by an electron spin resonance method after heating at 370° C. for 2 hours. Elastomer composition.
The radical concentration of the elastomer composition can be measured using the method described in the examples of the present specification.
〔２〕前記カーボンナノチューブの炭素純度が９０質量％以上である、上記〔１〕に記載のエラストマー組成物。
　カーボンナノチューブの炭素純度が上記所定値以上であれば、エラストマー組成物の耐熱性を更に向上させることができる。
　なお、本発明において、カーボンナノチューブの炭素純度は、本明細書の実施例に記載の方法を用いて測定することができる。 [2] The elastomer composition according to [1] above, wherein the carbon nanotube has a carbon purity of 90% by mass or more.
If the carbon purity of the carbon nanotube is at least the above predetermined value, the heat resistance of the elastomer composition can be further improved.
In addition, in the present invention, the carbon purity of carbon nanotubes can be measured using the method described in the examples of the present specification.
〔３〕前記カーボンナノチューブが単層カーボンナノチューブを含有する、上記〔１〕または〔２〕に記載のエラストマー組成物。
　カーボンナノチューブとして単層カーボンナノチューブを用いれば、エラストマー組成物の耐熱性を更に向上させることができる。 [3] The elastomer composition according to [1] or [2] above, wherein the carbon nanotubes contain single-walled carbon nanotubes.
If single-walled carbon nanotubes are used as the carbon nanotubes, the heat resistance of the elastomer composition can be further improved.
〔４〕前記カーボンナノチューブのＢＥＴ比表面積が６００ｍ２／ｇ以上である、上記〔１〕～〔３〕のいずれかに記載のエラストマー組成物。
　ＢＥＴ比表面積が上記所定値以上であるカーボンナノチューブを用いれば、エラストマー組成物の耐熱性を更に向上させることができる。
　なお、本発明において、「ＢＥＴ比表面積」とは、ＢＥＴ法を用いて測定した窒素吸着比表面積を指す。 [4] The elastomer composition according to any one of [1] to [3] above, wherein the carbon nanotube has a BET specific surface area of 600 m 2 /g or more.
The heat resistance of the elastomer composition can be further improved by using carbon nanotubes having a BET specific surface area equal to or greater than the predetermined value.
In the present invention, the "BET specific surface area" refers to the nitrogen adsorption specific surface area measured using the BET method.
〔５〕前記カーボンナノチューブの含有量が、前記フッ素含有エラストマー１００質量部に対して、０．１質量部以上１０質量部以下である、上記〔１〕～〔４〕のいずれかに記載のエラストマー組成物。
　カーボンナノチューブの含有量が上記所定の範囲内であれば、エラストマー組成物の耐熱性を更に向上させることができる。 [5] The elastomer according to any one of [1] to [4] above, wherein the content of the carbon nanotubes is 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the fluorine-containing elastomer. Composition.
If the content of carbon nanotubes is within the predetermined range, the heat resistance of the elastomer composition can be further improved.
〔６〕前記フッ素含有エラストマーが、四フッ化エチレン－パーフルオロアルキルビニルエーテル系ゴムを含有する、上記〔１〕～〔５〕のいずれかに記載のエラストマー組成物。
　フッ素含有エラストマーとして四フッ化エチレン－パーフルオロアルキルビニルエーテル系ゴム（ＦＦＫＭ）を用いれば、エラストマー組成物の耐熱性を更に向上させることができる。 [6] The elastomer composition according to any one of [1] to [5] above, wherein the fluorine-containing elastomer contains tetrafluoroethylene-perfluoroalkyl vinyl ether rubber.
By using tetrafluoroethylene-perfluoroalkyl vinyl ether rubber (FFKM) as the fluorine-containing elastomer, the heat resistance of the elastomer composition can be further improved.
　本発明によれば、耐熱性に優れたエラストマー組成物を提供することができる。 According to the present invention, an elastomer composition having excellent heat resistance can be provided.
　以下、本発明の実施形態について詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail.
（エラストマー組成物）
　本発明のエラストマー組成物は、フッ素含有エラストマーと、カーボンナノチューブとを含むエラストマー組成物であって、３７０℃で２時間加熱後に電子スピン共鳴法により測定されるラジカル濃度が所定値以上であることを特徴とする。
　本発明のエラストマー組成物は、３７０℃で２時間加熱後のラジカル濃度が所定値以上であるため、耐熱性に優れている。特に、本発明のエラストマー組成物は、３００℃を超える超高温下であっても良好に使用することができる。
　なお、本発明のエラストマー組成物は、フッ素含有エラストマーおよびカーボンナノチューブに加えて、架橋剤および添加剤を更に含んでいてもよい。 (Elastomer composition)
The elastomer composition of the present invention is an elastomer composition containing a fluorine-containing elastomer and carbon nanotubes, and after being heated at 370° C. for 2 hours, the radical concentration measured by the electron spin resonance method is equal to or higher than a predetermined value. Characterized by
The elastomer composition of the present invention has a radical concentration of a predetermined value or more after being heated at 370° C. for 2 hours, and thus has excellent heat resistance. In particular, the elastomer composition of the present invention can be used satisfactorily even at extremely high temperatures exceeding 300°C.
The elastomer composition of the present invention may further contain a cross-linking agent and additives in addition to the fluorine-containing elastomer and carbon nanotubes.
＜ラジカル濃度＞
　本発明のエラストマー組成物は、３７０℃で２時間加熱後に電子スピン共鳴法により測定されるラジカル濃度が、３×１０－７ｍｏｌ／ｇ以上であることが必要であり、３．５×１０－７ｍｏｌ／ｇ以上であることが好ましく、４×１０－７ｍｏｌ／ｇ以上であることがより好ましく、５×１０－７ｍｏｌ／ｇ以上であることが更に好ましく、６×１０－７ｍｏｌ／ｇ以上であることが一層好ましく、７×１０－７ｍｏｌ／ｇ以上であることがより一層好ましい。エラストマー組成物の上記ラジカル濃度の下限が３×１０－７ｍｏｌ／ｇ以上であれば、エラストマー組成物の耐熱性を十分に向上させることができる。ここで、上記で測定されるラジカル濃度は室温で安定なラジカルの濃度であるところ、エラストマー組成物を３７０℃で２時間加熱することにより発生したフッ素含有エラストマー由来のラジカルはＣＮＴによって捕捉され、室温で安定なラジカルとして上記測定で検出されると考えられる。このように加熱により発生したフッ素含有エラストマー由来のラジカルを安定なラジカルとして捕捉するＣＮＴの性能を「ＣＮＴのラジカル捕捉能」と称することがある。
　また、本発明のエラストマー組成物の上記ラジカル濃度の上限は、特に限定されないが、例えば、１×１０－５ｍｏｌ／ｇ以下である。
　なお、エラストマー組成物の上記ラジカル濃度は、フッ素含有エラストマーの種類、並びに、ＣＮＴの性状（例えば、炭素純度、層数、比表面積等）および含有量などによって制御することができる。また、エラストマー組成物の上記ラジカル濃度は、エラストマー組成物中におけるＣＮＴの解繊および分散の状態によっても制御することができる。そして、エラストマー組成物中におけるＣＮＴの解繊および分散の状態は、後述するエラストマー組成物の製造方法における条件、特に、分散工程における分散処理の条件によって制御することができる。 <Radical concentration>
The elastomer composition of the present invention must have a radical concentration of 3×10 −7 mol/g or more measured by an electron spin resonance method after heating at 370° C. for 2 hours, and 3.5×10 − It is preferably 7 mol/g or more, more preferably 4×10 −7 mol/g or more, still more preferably 5×10 −7 mol/g or more, and 6×10 −7 mol/g or more. g or more, and even more preferably 7×10 −7 mol/g or more. When the lower limit of the radical concentration of the elastomer composition is 3×10 −7 mol/g or more, the heat resistance of the elastomer composition can be sufficiently improved. Here, the radical concentration measured above is the concentration of radicals stable at room temperature. is detected as a stable radical in the above measurement. The ability of CNTs to capture the fluorine-containing elastomer-derived radicals generated by heating as stable radicals is sometimes referred to as "the ability of CNTs to capture radicals."
The upper limit of the radical concentration of the elastomer composition of the present invention is not particularly limited, but is, for example, 1×10 −5 mol/g or less.
The radical concentration of the elastomer composition can be controlled by the type of fluorine-containing elastomer, the properties of CNT (for example, carbon purity, number of layers, specific surface area, etc.) and content. In addition, the radical concentration of the elastomer composition can be controlled by the state of fibrillation and dispersion of CNTs in the elastomer composition. The state of fibrillation and dispersion of the CNTs in the elastomer composition can be controlled by the conditions in the method for producing the elastomer composition described below, particularly the conditions of the dispersion treatment in the dispersion step.
＜フッ素含有エラストマー＞
　フッ素含有エラストマーとしては、特に限定されることなく、既知のフッ素ゴムを用いることができる。具体的には、フッ素含有エラストマーとしては、例えば、フッ化ビニリデン系ゴム（ＦＫＭ）、四フッ化エチレン－プロピレン系ゴム（ＦＥＰＭ）、パーフルオロエラストマーとしての四フッ化エチレン－パーフルオロアルキルビニルエーテル系ゴム（ＦＦＫＭ）、テトラフルオロエチレン系ゴム（ＴＦＥ）などが挙げられる。これらは、１種単独で使用してもよいし、２種以上を併用してもよい。 <Fluorine-containing elastomer>
Known fluororubbers can be used as the fluorine-containing elastomer without any particular limitation. Specifically, examples of fluorine-containing elastomers include vinylidene fluoride rubber (FKM), tetrafluoroethylene-propylene rubber (FEPM), and tetrafluoroethylene-perfluoroalkyl vinyl ether rubber as perfluoroelastomers. (FFKM), tetrafluoroethylene rubber (TFE), and the like. These may be used individually by 1 type, and may use 2 or more types together.
　ここで、フッ化ビニリデン系ゴム（ＦＫＭ）は、フッ化ビニリデンを主成分とし、耐熱性、耐油性、耐薬品性、耐溶剤性、加工性などに優れるフッ素ゴムである。ＦＫＭとしては、特に限定されないが、例えば、フッ化ビニリデンとヘキサフルオロプロピレンとからなる二元共重合体、フッ化ビニリデンとヘキサフルオロプロピレンとテトラフルオロエチレンとからなる三元共重合体、フッ化ビニリデンとヘキサフルオロプロピレンとテトラフルオロエチレンと加硫サイトモノマーとからなる四元共重合体などが挙げられる。市販品としては、例えば、ケマーズ株式会社の「バイトン（登録商標）」、ダイキン工業株式会社の「ダイエル（登録商標）Ｇ」などが挙げられる。中でもフッ化ビニリデンとヘキサフルオロプロピレンとテトラフルオロエチレンと加硫サイトモノマーとからなる四元共重合体が好ましい。当該四元共重合体は、例えば、市販品「バイトンＧＢＬ－２００Ｓ」（ケマーズ株式会社製）として入手可能である。なお、本明細書において、「フッ化ビニリデンを主成分」とするとは、フッ化ビニリデン系ゴム中に含まれるフッ化ビニリデン単位が５０質量％以上、好ましくは５０質量％超であることをいう。 Here, the vinylidene fluoride rubber (FKM) is a fluororubber that has vinylidene fluoride as its main component and is excellent in heat resistance, oil resistance, chemical resistance, solvent resistance, workability, and the like. Examples of FKM include, but are not limited to, a binary copolymer of vinylidene fluoride and hexafluoropropylene, a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, and vinylidene fluoride. and hexafluoropropylene, tetrafluoroethylene, and vulcanization site monomers. Commercially available products include, for example, "Viton (registered trademark)" from Chemours Co., Ltd., and "Dail (registered trademark) G" from Daikin Industries, Ltd. Among them, a quaternary copolymer composed of vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene and a vulcanization site monomer is preferred. The quaternary copolymer is available, for example, as a commercial product "Viton GBL-200S" (manufactured by Chemours Co., Ltd.). In this specification, "mainly composed of vinylidene fluoride" means that the vinylidene fluoride unit contained in the vinylidene fluoride rubber is 50% by mass or more, preferably more than 50% by mass.
　四フッ化エチレン－プロピレン系ゴム（ＦＥＰＭ）は、テトラフルオロエチレンとプロピレンとの交互共重合体をベースとし、耐熱性、耐薬品性、耐極性溶剤性、耐スチーム性などに優れるフッ素ゴムである。ＦＥＰＭとしては、特に限定されないが、例えば、テトラフルオロエチレンとプロピレンとからなる二元共重合体、テトラフルオロエチレンとプロピレンとフッ化ビニリデンとからなる三元共重合体、テトラフルオロエチレンとプロピレンと架橋点モノマーとからなる三元共重合体などが挙げられる。テトラフルオロエチレンとプロピレンとからなる二元共重合体の市販品としては、例えば、ＡＧＣ株式会社の「アフラス（登録商標）１００」及び「アフラス１５０」が挙げられる。テトラフルオロエチレンとプロピレンとフッ化ビニリデンとからなる三元共重合体の市販品としては、例えば、ＡＧＣ株式会社の「アフラス２００」が挙げられる。テトラフルオロエチレンとプロピレンと架橋点モノマーとからなる三元共重合体の市販品としては、例えば、ＡＧＣ株式会社の「アフラス３００」が挙げられる。 Tetrafluoroethylene-propylene rubber (FEPM) is a fluororubber based on an alternating copolymer of tetrafluoroethylene and propylene, and has excellent heat resistance, chemical resistance, polar solvent resistance, steam resistance, etc. . Examples of FEPM include, but are not limited to, a binary copolymer of tetrafluoroethylene and propylene, a terpolymer of tetrafluoroethylene, propylene and vinylidene fluoride, and crosslinked with tetrafluoroethylene and propylene. terpolymers composed of point monomers and the like. Examples of commercially available binary copolymers of tetrafluoroethylene and propylene include "AFRAS (registered trademark) 100" and "AFRAS 150" manufactured by AGC Corporation. Commercially available terpolymers composed of tetrafluoroethylene, propylene and vinylidene fluoride include, for example, "AFRAS 200" manufactured by AGC Corporation. Commercially available terpolymers composed of tetrafluoroethylene, propylene, and cross-linking monomers include, for example, "AFRAS 300" manufactured by AGC Corporation.
　四フッ化エチレン－パーフルオロアルキルビニルエーテル系ゴム（ＦＦＫＭ）は、主鎖炭素（Ｃ）－炭素（Ｃ）結合を構成する炭素原子に結合している水素原子（Ｈ）が完全にフッ素化されているフッ素ゴムであり、耐熱性や耐薬品性、耐プラズマ性に優れ、半導体装置用シール部材として好適に用いることができる。ＦＦＫＭは、テトラフルオロエチレン（ＴＦＥ）由来の構成単位と、パーフルオロアルキルビニルエーテル（ＰＡＶＥ）又はパーフルオロアルコキシアルキルビニルエーテル（ＰＡＯＶＥ）由来の構成単位とを含む共重合体を挙げることができる。ＦＦＫＭは、前記２つの構成単位に加えて、架橋部位を有する構成単位をさらに含んでいてもよい。 Polytetrafluoroethylene-perfluoroalkyl vinyl ether rubber (FFKM) has hydrogen atoms (H) bonded to the carbon atoms that make up the main chain carbon (C)-carbon (C) bonds completely fluorinated. It is a fluororubber with excellent heat resistance, chemical resistance, and plasma resistance, and can be suitably used as a sealing member for semiconductor devices. FFKM can include a copolymer containing structural units derived from tetrafluoroethylene (TFE) and structural units derived from perfluoroalkyl vinyl ether (PAVE) or perfluoroalkoxyalkyl vinyl ether (PAOVE). FFKM may further contain a structural unit having a cross-linking site in addition to the above two structural units.
　パーフルオロアルキルビニルエーテル（ＰＡＶＥ）は、アルキル基の炭素数が１～５のものを用いることができ、例えば、パーフルオロメチルビニルエーテル（ＰＭＶＥ）、パーフルオロエチルビニルエーテル（ＰＥＶＥ）、パーフルオロプロピルビニルエーテル（ＰＰＶＥ）等を挙げることができる。 Perfluoroalkyl vinyl ethers (PAVE) having alkyl groups of 1 to 5 carbon atoms can be used. For example, perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), perfluoropropyl vinyl ether (PPVE ) etc. can be mentioned.
　パーフルオロアルコキシアルキルビニルエーテル（ＰＡＯＶＥ）は、ビニルエーテル基（ＣＦ2＝ＣＦＯ－）に結合する基の炭素数が３～１１であることができ、例えば
　　ＣＦ2＝ＣＦＯＣＦ2ＣＦ（ＣＦ3）ＯＣnＦ2n+1、
　　ＣＦ2＝ＣＦＯ（ＣＦ2）3ＯＣnＦ2n+1、
　　ＣＦ2＝ＣＦＯＣＦ2ＣＦ（ＣＦ3）Ｏ（ＣＦ2Ｏ）mＣnＦ2n+1、又は
　　ＣＦ2＝ＣＦＯ（ＣＦ2）2ＯＣnＦ2n+1
　を挙げることができる。ここで、ｎは例えば１～５の整数であり、ｍは例えば１～３の整数である。 Perfluoroalkoxyalkyl vinyl ether (PAOVE) may have 3 to 11 carbon atoms in the group bonded to the vinyl ether group (CF 2 ═CFO—), for example CF 2 ═CFOCF 2 CF(CF 3 )OC n F 2n+1 ,
CF2 =CFO( CF2 ) 3OCnF2n + 1 ,
CF2 = CFOCF2CF ( CF3 )O( CF2O ) mCnF2n +1 or CF2 =CFO( CF2 ) 2OCnF2n +1
can be mentioned. Here, n is an integer of 1 to 5, for example, and m is an integer of 1 to 3, for example.
　ＦＦＫＭとしては、例えば、ＡＧＣ株式会社の「アフラス（登録商標）ＰＭ１１００」及び「アフラスＰＭ３０００」及び「アフラスＰＭ４０００」、デュポン社の「カルレッツ（登録商標）」シリーズ、ダイキン工業株式会社の「ダイエル（登録商標）パーフロ」シリーズ、ソルベイ社の「テクノフロン（登録商標）ＰＦＲ」シリーズ、３Ｍ社の「ダイニオン（登録商標）」シリーズが挙げられる。 Examples of FFKM include AGC Corporation's "Afras (registered trademark) PM1100", "Afras PM3000" and "Afras PM4000", DuPont's "Kalrez (registered trademark)" series, Daikin Industries, Ltd. (trademark) Perflo" series, Solvay's "Technoflon (registered trademark) PFR" series, and 3M Company's "Dynion (registered trademark)" series.
　そして、得られるエラストマー組成物の耐熱性を更に向上させる観点から、フッ素含有エラストマーとしては、四フッ化エチレン－パーフルオロアルキルビニルエーテル系ゴム（ＦＦＫＭ）を用いることが好ましい。 From the viewpoint of further improving the heat resistance of the resulting elastomer composition, it is preferable to use tetrafluoroethylene-perfluoroalkyl vinyl ether rubber (FFKM) as the fluorine-containing elastomer.
＜カーボンナノチューブ＞
　カーボンナノチューブ（ＣＮＴ）としては、例えば、後述する第１の態様のもの、および第２の態様のものなどを用いることができる。なお、ＣＮＴは、１本ずつに解繊された状態となる場合もあるし、複数本のＣＮＴがバンドル状に形成されたカーボンナノチューブ集合体として構成された状態となる場合もある。 <Carbon nanotube>
As the carbon nanotube (CNT), for example, those of the first aspect and the second aspect, which will be described later, can be used. The CNTs may be disentangled one by one, or may be configured as a carbon nanotube aggregate in which a plurality of CNTs are formed into a bundle.
＜＜第１の態様について＞＞
　第１の態様に係るＣＮＴとしては、以下のものを挙げることができる。
　ＣＮＴの種類としては、特に限定されず、単層カーボンナノチューブ（「ＳＷＣＮＴ」と略記する場合がある。）、多層カーボンナノチューブ（「ＭＷＣＮＴ」と略記する場合がある）が含まれる。また、複数本のＣＮＴは、単層から５層までのカーボンナノチューブを主として含むことが好ましく、単層カーボンナノチューブを主として含むことがより好ましい。比較的層数の少ないＣＮＴ、特に単層ＣＮＴを含むことにより、ＣＮＴのラジカル捕捉能を高めて、エラストマー組成物の耐熱性を更に向上させると共に、配合量が少量であってもエラストマー組成物の特性（例えば、導電性、熱伝導性、強度など）が向上するからである。なお、前述した「主として含む」とは、複数本のカーボンナノチューブの全本数のうち、半数超を含むことをいう。 <<About the first aspect>>
Examples of CNTs according to the first aspect include the following.
The type of CNT is not particularly limited, and includes single-walled carbon nanotubes (sometimes abbreviated as “SWCNT”) and multi-walled carbon nanotubes (sometimes abbreviated as “MWCNT”). In addition, the plurality of CNTs preferably mainly contain carbon nanotubes having from a single wall to five walls, and more preferably mainly contain single-walled carbon nanotubes. By including CNTs having a relatively small number of layers, particularly single-walled CNTs, the radical scavenging ability of the CNTs is enhanced, the heat resistance of the elastomer composition is further improved, and even if the amount is small, the elastomer composition can be improved. This is because the properties (for example, electrical conductivity, thermal conductivity, strength, etc.) are improved. The above-mentioned "mainly including" means including more than half of the total number of the plurality of carbon nanotubes.
　ＣＮＴの平均直径は、１ｎｍ以上であることが好ましく、６０ｎｍ以下であることが好ましく、３０ｎｍ以下であることがより好ましく、１０ｎｍ以下であることが更に好ましい。ＣＮＴの平均直径を上記所定の範囲内とすれば、エラストマー組成物の特性（例えば、導電性、熱伝導性、強度など）を向上させることができる。ここで、本発明において、ＣＮＴの「平均直径」は、透過型電子顕微鏡（ＴＥＭ）画像上で、例えば、２０本のＣＮＴについて直径（外径）を測定し、個数平均値を算出することで求めることができる。 The average diameter of CNTs is preferably 1 nm or more, preferably 60 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. If the average diameter of the CNTs is within the above-specified range, the properties of the elastomer composition (eg electrical conductivity, thermal conductivity, strength, etc.) can be improved. Here, in the present invention, the "average diameter" of CNTs is obtained by measuring the diameter (outer diameter) of, for example, 20 CNTs on a transmission electron microscope (TEM) image and calculating the number average value. can ask.
　ＣＮＴとしては、平均直径（Ａｖ）に対する、直径の標準偏差（σ：標本標準偏差）に３を乗じた値（３σ）の比（３σ／Ａｖ）が０．２０超０．８０未満のＣＮＴを用いることが好ましく、３σ／Ａｖが０．２５超のＣＮＴであることがより好ましく、３σ／Ａｖが０．５０超のＣＮＴがさらに好ましい。３σ／Ａｖが上記所定の範囲内であれば、エラストマー組成物の特性（例えば、導電性、熱伝導性、強度など）を向上させることができる。なお、ＣＮＴの平均直径（Ａｖ）及び標準偏差（σ）は、ＣＮＴの製造方法や製造条件を変更することにより調整してもよいし、異なる製法で得られたＣＮＴを複数種類組み合わせることにより調整してもよい。 As the CNT, the ratio (3σ/Av) of the value (3σ) obtained by multiplying the standard deviation of the diameter (σ: sample standard deviation) by 3 to the average diameter (Av) is CNT having a ratio (3σ/Av) of more than 0.20 and less than 0.80. CNTs with 3σ/Av greater than 0.25 are more preferable, and CNTs with 3σ/Av greater than 0.50 are even more preferable. If 3σ/Av is within the predetermined range, the properties of the elastomer composition (eg electrical conductivity, thermal conductivity, strength, etc.) can be improved. The average diameter (Av) and standard deviation (σ) of CNTs may be adjusted by changing the CNT manufacturing method or manufacturing conditions, or by combining multiple types of CNTs obtained by different manufacturing methods. You may
　ＣＮＴとしては、前述のようにして測定した直径を横軸に、その頻度を縦軸に取ってプロットし、ガウシアンで近似した際に、正規分布を取るものが通常使用される。 As the CNT, the diameter measured as described above is plotted on the horizontal axis and the frequency is plotted on the vertical axis, and when Gaussian approximation is performed, a normal distribution is usually used.
　ＣＮＴは、平均長さが、１０μｍ以上であることが好ましく、５０μｍ以上であることがより好ましく、８０μｍ以上であることが更に好ましく、６００μｍ以下であることが好ましく、５５０μｍ以下であることがより好ましく、５００μｍ以下であることが更に好ましい。ＣＮＴの平均長さを上記所定の範囲内とすれば、エラストマー組成物の特性（例えば、導電性、熱伝導性、強度など）を向上させることができる。なお、本発明において、ＣＮＴの「平均長さ」は、走査型電子顕微鏡（ＳＥＭ）画像上で、例えば、２０本のＣＮＴについて長さを測定し、個数平均値を算出することで求めることができる。 The average length of CNTs is preferably 10 µm or more, more preferably 50 µm or more, still more preferably 80 µm or more, preferably 600 µm or less, and more preferably 550 µm or less. , 500 μm or less. If the average length of the CNTs is within the predetermined range, the properties of the elastomer composition (eg electrical conductivity, thermal conductivity, strength, etc.) can be improved. In the present invention, the "average length" of CNTs can be obtained by measuring the length of, for example, 20 CNTs on a scanning electron microscope (SEM) image and calculating the number average value. can.
　ＣＮＴは、通常、アスペクト比が１０超である。なお、ＣＮＴのアスペクト比は、走査型電子顕微鏡又は透過型電子顕微鏡を用いて、無作為に選択したＣＮＴ２０本の直径及び長さを測定し、直径と長さとの比（長さ／直径）の平均値を算出することにより求めることができる。 CNTs usually have an aspect ratio of more than 10. The aspect ratio of CNTs is determined by measuring the diameter and length of 20 randomly selected CNTs using a scanning electron microscope or transmission electron microscope, and measuring the ratio of the diameter to the length (length/diameter). It can be obtained by calculating the average value.
　ＣＮＴは、ＢＥＴ比表面積が、６００ｍ２／ｇ以上であることが好ましく、８００ｍ２／ｇ以上であることがより好ましく、２０００ｍ２／ｇ以下であることが好ましく、１８００ｍ２／ｇ以下であることがより好ましく、１６００ｍ２／ｇ以下であることが更に好ましい。ＣＮＴのＢＥＴ比表面積が６００ｍ２／ｇ以上であれば、ＣＮＴのラジカル捕捉能を高めて、エラストマー組成物の耐熱性を更に向上させると共に、少ない配合量でエラストマー組成物の特性（例えば、導電性、熱伝導性、強度など）を高めることができる。また、ＣＮＴのＢＥＴ比表面積が２０００ｍ２／ｇ以下であれば、ＣＮＴのバンドル構造体を良好に解繊することができる。 The CNT preferably has a BET specific surface area of 600 m 2 /g or more, more preferably 800 m 2 /g or more, preferably 2000 m 2 /g or less, and 1800 m 2 /g or less. is more preferable, and 1600 m 2 /g or less is even more preferable. If the BET specific surface area of the CNTs is 600 m 2 /g or more, the radical scavenging ability of the CNTs is enhanced, the heat resistance of the elastomer composition is further improved, and properties of the elastomer composition (e.g., conductivity , thermal conductivity, strength, etc.). Further, when the BET specific surface area of CNT is 2000 m 2 /g or less, the CNT bundle structure can be defibrated satisfactorily.
　ＣＮＴは、吸着等温線から得られるｔ－プロットが上に凸な形状を示すことが好ましい。なお、「ｔ－プロット」は、窒素ガス吸着法により測定されたＣＮＴの吸着等温線において、相対圧を窒素ガス吸着層の平均厚みｔ（ｎｍ）に変換することにより得ることができる。すなわち、窒素ガス吸着層の平均厚みｔを相対圧Ｐ／Ｐ０に対してプロットした、既知の標準等温線から、相対圧に対応する窒素ガス吸着層の平均厚みｔを求めて前記変換を行うことにより、ＣＮＴのｔ－プロットが得られる（de Boerらによるｔ－プロット法）。なお、吸着等温線から得られるｔ－プロットが上に凸な形状を示すＣＮＴは、開口処理が施されていないＣＮＴであることが好ましい。 For CNTs, the t-plot obtained from the adsorption isotherm preferably shows an upward convex shape. The "t-plot" can be obtained by converting the relative pressure to the average thickness t (nm) of the nitrogen gas adsorption layer in the CNT adsorption isotherm measured by the nitrogen gas adsorption method. That is, the conversion is performed by obtaining the average thickness t of the nitrogen gas adsorption layer corresponding to the relative pressure from a known standard isotherm obtained by plotting the average thickness t of the nitrogen gas adsorption layer against the relative pressure P/P0. gives a t-plot of CNTs (t-plot method by de Boer et al.). It should be noted that CNTs exhibiting a convex shape in the t-plot obtained from the adsorption isotherm are preferably CNTs that have not undergone opening treatment.
　ここで、表面に細孔を有する物質では、窒素ガス吸着層の成長は、次の（１）～（３）の過程に分類される。そして、下記の（１）～（３）の過程によって、ｔ－プロットの傾きに変化が生じる。
（１）全表面への窒素分子の単分子吸着層形成過程
（２）多分子吸着層形成とそれに伴う細孔内での毛管凝縮充填過程
（３）細孔が窒素によって満たされた見かけ上の非多孔性表面への多分子吸着層形成過程 Here, the growth of a nitrogen gas adsorption layer on a substance having pores on its surface is classified into the following processes (1) to (3). Then, the slope of the t-plot changes due to the following processes (1) to (3).
(1) Formation of a monomolecular adsorption layer of nitrogen molecules on the entire surface (2) Formation of a multimolecular adsorption layer and subsequent capillary condensation filling process within the pores (3) Posterior pores filled with nitrogen Formation process of polymolecular adsorption layer on non-porous surface
　上に凸な形状を示すｔ－プロットは、窒素ガス吸着層の平均厚みｔが小さい領域では、原点を通る直線上にプロットが位置するのに対し、ｔが大きくなると、プロットが当該直線から下にずれた位置となる。かかるｔ－プロットの形状を有するＣＮＴは、ＣＮＴの全比表面積に対する内部比表面積の割合が大きく、ＣＮＴを構成する炭素ナノ構造体に多数の開口が形成されていることを示している。 The t-plot showing an upwardly convex shape is located on a straight line passing through the origin in a region where the average thickness t of the nitrogen gas adsorption layer is small, whereas when t increases, the plot moves downward from the straight line. position shifted to A CNT having such a t-plot shape has a large ratio of internal specific surface area to the total specific surface area of the CNT, indicating that a large number of openings are formed in the carbon nanostructure constituting the CNT.
　なお、ＣＮＴのｔ－プロットの屈曲点は、０．２≦ｔ（ｎｍ）≦１．５を満たす範囲にあることが好ましく、０．４５≦ｔ（ｎｍ）≦１．５の範囲にあることがより好ましく、０．５５≦ｔ（ｎｍ）≦１．０の範囲にあることが更に好ましい。ＣＮＴのｔ－プロットの屈曲点がかかる範囲内にあれば、少ない配合量でエラストマー組成物の特性（例えば、導電性、熱伝導性、強度など）を高めることができる。なお、「屈曲点の位置」は、前述した（１）の過程の近似直線Ａと、前述した（３）の過程の近似直線Ｂとの交点である。 The inflection point of the t-plot of CNT is preferably in the range that satisfies 0.2 ≤ t (nm) ≤ 1.5, and is in the range of 0.45 ≤ t (nm) ≤ 1.5. is more preferable, and it is even more preferable to be in the range of 0.55≦t(nm)≦1.0. If the inflection point of the t-plot of CNT is within such a range, it is possible to enhance the properties (eg electrical conductivity, thermal conductivity, strength, etc.) of the elastomer composition with a small amount. The "position of the bending point" is the intersection of the approximate straight line A in the process (1) described above and the approximate straight line B in the process (3) described above.
　因みに、ＣＮＴの吸着等温線の測定、ｔ－プロットの作成、及び、ｔ－プロットの解析に基づく全比表面積Ｓ１と内部比表面積Ｓ２との算出は、例えば、市販の測定装置である「ＢＥＬＳＯＲＰ（登録商標）－ｍｉｎｉ」（日本ベル（株）製）を用いて行うことができる。 By the way, the measurement of the adsorption isotherm of CNT, the creation of the t-plot, and the calculation of the total specific surface area S1 and the internal specific surface area S2 based on the analysis of the t-plot can be performed, for example, by a commercially available measurement device "BELSORP ( (registered trademark)-mini” (manufactured by Nippon Bell Co., Ltd.).
　ＣＮＴは、ラマン分光法を用いて評価した際に、ＲａｄｉａｌＢｒｅａｔｈｉｎｇ Ｍｏｄｅ（ＲＢＭ）のピークを有することが好ましい。なお、三層以上の多層ＣＮＴのラマンスペクトルには、ＲＢＭが存在しない。 The CNT preferably has a Radial Breathing Mode (RBM) peak when evaluated using Raman spectroscopy. In addition, RBM does not exist in the Raman spectrum of multilayer CNTs having three or more layers.
　また、ＣＮＴは、ラマンスペクトルにおけるＤバンドピーク強度に対するＧバンドピーク強度の比（Ｇ／Ｄ比）が０．５以上５．０以下であることが好ましく、１．０以上とすることができ、４．０以下としてもよい。Ｇ／Ｄ比が０．５以上５．０以下であれば、エラストマー組成物の特性（例えば、導電性、熱伝導性、強度など）を向上させることができる。 In addition, the ratio of the G band peak intensity to the D band peak intensity (G/D ratio) in the Raman spectrum of the CNT is preferably 0.5 or more and 5.0 or less, and can be 1.0 or more. It may be 4.0 or less. If the G/D ratio is 0.5 or more and 5.0 or less, the properties (eg electrical conductivity, thermal conductivity, strength, etc.) of the elastomer composition can be improved.
　ＣＮＴの炭素純度は、９０質量％であることが好ましく、９４質量％以上であることがより好ましく、９６質量％以上であることが更に好ましく、９８質量％以上であることが一層好ましく、９９質量％以上であることがより一層好ましい。ＣＮＴの炭素純度が上記下限以上であれば、ＣＮＴのラジカル捕捉能を高めて、エラストマー組成物の耐熱性を更に向上させることができる。
　なお、ＣＮＴの炭素純度の上限は、特に限定されないが、例えば、９９．９９９９質量％以下である。 The carbon purity of CNT is preferably 90% by mass, more preferably 94% by mass or more, still more preferably 96% by mass or more, even more preferably 98% by mass or more, and 99% by mass. % or more is even more preferable. If the carbon purity of the CNTs is equal to or higher than the above lower limit, the radical scavenging ability of the CNTs can be enhanced, and the heat resistance of the elastomer composition can be further improved.
Although the upper limit of the carbon purity of CNT is not particularly limited, it is, for example, 99.9999% by mass or less.
　なお、ＣＮＴは、特に限定されることなく、アーク放電法、レーザーアブレーション法、化学的気相成長法（ＣＶＤ法）などの既知のＣＮＴの合成方法を用いて製造することができる。具体的には、ＣＮＴは、例えば、ＣＮＴ製造用の触媒層を表面に有する基材上に原料化合物及びキャリアガスを供給し、化学的気相成長法（ＣＶＤ法）によりＣＮＴを合成する際に、系内に微量の酸化剤（触媒賦活物質）を存在させることで、触媒層の触媒活性を飛躍的に向上させるという方法（スーパーグロース法；国際公開第２００６／０１１６５５号参照）に準じて、効率的に製造することができる。なお、以下では、スーパーグロース法により得られるＣＮＴを「ＳＧＣＮＴ」と称することがある。スーパーグロース法により製造されたＣＮＴは、ＳＧＣＮＴのみから構成されていてもよいし、ＳＧＣＮＴに加え、例えば、非円筒形状の炭素ナノ構造体等の他の炭素ナノ構造体を含んでいてもよい。 Note that CNTs can be produced using known CNT synthesis methods such as an arc discharge method, a laser ablation method, and a chemical vapor deposition method (CVD method), without being particularly limited. Specifically, CNTs are synthesized, for example, by supplying a raw material compound and a carrier gas onto a substrate having a catalyst layer for CNT production on its surface, and synthesizing CNTs by chemical vapor deposition (CVD). , A method of dramatically improving the catalytic activity of the catalyst layer by allowing a trace amount of oxidizing agent (catalyst activating substance) to be present in the system (super-growth method; see WO 2006/011655), It can be manufactured efficiently. In addition, below, the CNT obtained by the super-growth method may be referred to as "SGCNT". CNTs produced by the super-growth method may consist of SGCNTs only, or may contain other carbon nanostructures such as non-cylindrical carbon nanostructures in addition to SGCNTs.
＜＜第２の態様＞＞
　第２の態様に係るＣＮＴとしては、以下のものを挙げることができる。
　第２の態様に係るＣＮＴからなるＣＮＴ集合体は、以下の（１）～（３）の条件のうち少なくとも１つを満たし、マトリクス（本発明ではフッ素含有エラストマー）への分散性に優れるものである。
　・条件（１）カーボンナノチューブ集合体を、バンドル長が１０μｍ以上になるように分散させて得たカーボンナノチューブ分散体について、フーリエ変換赤外分光分析して得たスペクトルにおいて、カーボンナノチューブ分散体のプラズモン共鳴に基づくピークが、波数３００ｃｍ-1超２０００ｃｍ-1以下の範囲に、少なくとも１つ存在する。
　・条件（２）カーボンナノチューブ集合体について測定した微分細孔容量分布における最大のピークが、細孔径１００ｎｍ超４００ｎｍ未満の範囲にある。
　・条件（３）カーボンナノチューブ集合体の電子顕微鏡画像の二次元空間周波数スペクトルのピークが、１μｍ-1以上１００μｍ-1以下の範囲に少なくとも１つ存在する。 <<Second aspect>>
Examples of CNTs according to the second aspect include the following.
A CNT aggregate composed of CNTs according to the second aspect satisfies at least one of the following conditions (1) to (3) and is excellent in dispersibility in a matrix (fluorine-containing elastomer in the present invention). be.
・Condition (1) A carbon nanotube dispersion obtained by dispersing a carbon nanotube aggregate so that the bundle length is 10 μm or more, in the spectrum obtained by Fourier transform infrared spectroscopic analysis, the plasmon of the carbon nanotube dispersion At least one peak based on resonance exists in the wavenumber range of more than 300 cm −1 and less than or equal to 2000 cm −1 .
· Condition (2) The maximum peak in the differential pore volume distribution measured for the aggregate of carbon nanotubes is in the range of pore diameters of more than 100 nm and less than 400 nm.
· Condition (3) At least one peak of the two-dimensional spatial frequency spectrum of the electron microscope image of the aggregate of carbon nanotubes exists in the range of 1 µm -1 to 100 µm -1 .
　前記条件（１）～（３）のうちの少なくとも１つを満たすＣＮＴ集合体が分散性に優れる理由は明らかではないが、以下の通りであると推察される。すなわち、前記条件（１）～（３）のうちの少なくとも１つを満たすＣＮＴ集合体を構成するＣＮＴは、波状構造を有する。かかる「波状構造」に起因して、ＣＮＴ集合体を構成する各ＣＮＴ間における相互作用が抑制され得ると推察される。各ＣＮＴ間における相互作用が抑制されていれば、ＣＮＴ集合体に含まれる各ＣＮＴが強固にバンドル化すること及び凝集化することが抑制され得る。これにより、ＣＮＴ集合体を容易に分散させることが可能となり得る。さらに、ＣＮＴ集合体が容易に分散可能であれば、かかるＣＮＴ集合体の二次加工容易性が向上する、という効果が生じる。 The reason why the CNT aggregate satisfying at least one of the conditions (1) to (3) is excellent in dispersibility is not clear, but is presumed to be as follows. That is, the CNTs constituting the CNT aggregate that satisfies at least one of the conditions (1) to (3) have a wavy structure. It is speculated that due to such a "wavy structure", interaction between CNTs constituting the CNT aggregate can be suppressed. If the interaction between CNTs is suppressed, it is possible to suppress the strong bundling and agglomeration of the CNTs contained in the CNT aggregate. This can make it possible to easily disperse the CNT aggregates. Furthermore, if the CNT aggregates can be easily dispersed, there is an effect that the easiness of secondary processing of such CNT aggregates is improved.
－条件（１）－
　条件（１）において、波数３００ｃｍ-1超２０００ｃｍ-1以下の範囲に、好ましくは波数５００ｃｍ-1以上２０００ｃｍ-1以下の範囲に、より好ましくは波数７００ｃｍ-1以上２０００ｃｍ-1以下の範囲に、ＣＮＴのプラズモン共鳴に基づくピークが存在していれば、かかるＣＮＴは良好な分散性を呈し得る。 -Condition (1)-
In the condition (1), the wave number is in the range of more than 300 cm -1 and 2000 cm -1 or less, preferably in the wave number range of 500 cm -1 or more and 2000 cm -1 or less, more preferably in the wave number range of 700 cm -1 or more and 2000 cm -1 or less, If a peak based on plasmon resonance of CNTs is present, such CNTs can exhibit good dispersibility.
　なお、フーリエ変換赤外分光分析により得られたスペクトルにおいて、カーボンナノチューブ分散体のプラズモン共鳴に基づく比較的緩やかなピーク以外に、波数８４０ｃｍ-1付近、１３００ｃｍ-1付近、及び１７００ｃｍ-1付近に、鋭いピークが確認されることがある。これらの鋭いピークは、「カーボンナノチューブ分散体のプラズモン共鳴に基づくピーク」には該当せず、それぞれが、官能基由来の赤外吸収に対応している。より具体的には、波数８４０ｃｍ-1付近の鋭いピークは、Ｃ－Ｈ面外変角振動に起因し；波数１３００ｃｍ-1付近の鋭いピークは、エポキシ三員環伸縮振動に起因し；波数１７００ｃｍ-1付近の鋭いピークは、Ｃ＝Ｏ伸縮振動に起因する。 In the spectrum obtained by Fourier transform infrared spectroscopy, in addition to the relatively gentle peaks based on the plasmon resonance of the carbon nanotube dispersion, wavenumbers near 840 cm -1 , 1300 cm -1 and 1700 cm -1 , A sharp peak may be observed. These sharp peaks do not correspond to "peaks based on plasmon resonance of carbon nanotube dispersion", and each corresponds to infrared absorption derived from functional groups. More specifically, the sharp peak near wavenumber 840 cm is attributed to CH out-of-plane bending vibration; the sharp peak near wavenumber 1300 cm is attributed to epoxy three-membered ring stretching vibration; wavenumber 1700 cm. A sharp peak near -1 is attributed to C=O stretching vibration.
　ここで、条件（１）において、フーリエ変換赤外分光分析によるスペクトルを取得するにあたり、バンドル長が１０μｍ以上になるように、カーボンナノチューブ集合体を分散させることにより、カーボンナノチューブ分散体を得る必要がある。ここで、例えば、カーボンナノチューブ集合体、水、及び界面活性剤（例えば、ドデシルベンゼンスルホン酸ナトリウム）を適切な比率で配合して、超音波等により所定時間にわたり撹拌処理することで、水中に、バンドル長が１０μｍ以上であるカーボンナノチューブ分散体が分散されてなる分散液を得ることができる。 Here, in condition (1), in acquiring a spectrum by Fourier transform infrared spectroscopy, it is necessary to obtain a carbon nanotube dispersion by dispersing the aggregate of carbon nanotubes so that the bundle length is 10 μm or more. be. Here, for example, a carbon nanotube aggregate, water, and a surfactant (for example, sodium dodecylbenzenesulfonate) are blended in an appropriate ratio, and stirred for a predetermined time by ultrasonic waves or the like to obtain A dispersion liquid in which a carbon nanotube dispersion having a bundle length of 10 μm or more is dispersed can be obtained.
　カーボンナノチューブ分散体のバンドル長は、湿式画像解析型の粒度測定装置により解析することで、得ることができる。かかる測定装置は、カーボンナノチューブ分散体を撮影して得られた画像から、各分散体の面積を算出して、算出した面積を有する円の直径（以下、ＩＳＯ円径（ＩＳＯ ａｒｅａ ｄｉａｍｅｔｅｒ）とも称することがある）を得ることができる。そして、本明細書では、各分散体のバンドル長は、このようにして得られるＩＳＯ円径の値であるものとして、定義した。 The bundle length of the carbon nanotube dispersion can be obtained by analyzing it with a wet image analysis type particle size measuring device. Such a measurement device calculates the area of each dispersion from the image obtained by photographing the carbon nanotube dispersion, and the diameter of the circle having the calculated area (hereinafter also referred to as ISO area diameter) can be obtained). In this specification, the bundle length of each dispersion is defined as the value of the ISO circle diameter thus obtained.
－条件（２）－
　カーボンナノチューブ集合体の微分細孔容量分布は、液体窒素の７７Ｋでの吸着等温線から、ＢＪＨ（Ｂａｒｒｅｔｔ－Ｊｏｙｎｅｒ－Ｈａｌｅｎｄａ）法に基づいて求めることができる。なお、ＢＪＨ法は、細孔がシリンダ状であると仮定して細孔径分布を求める測定法である。カーボンナノチューブ集合体について測定した微分細孔容量分布におけるピークが１００ｎｍ超の範囲にあるということは、カーボンナノチューブ集合体において、ＣＮＴ間にある程度の大きさの空隙が存在し、ＣＮＴが過度に過密に凝集した状態となっていないことを意味する。なお、上限の４００ｎｍは、実施例で用いた測定装置（ＢＥＬＳＯＲＰ－ｍｉｎｉ ＩＩ）における測定限界である。 -Condition (2)-
The differential pore volume distribution of the aggregate of carbon nanotubes can be obtained from the adsorption isotherm of liquid nitrogen at 77K based on the BJH (Barrett-Joyner-Halenda) method. The BJH method is a measurement method for determining the pore size distribution assuming that the pores are cylindrical. The fact that the peak in the differential pore volume distribution measured for the carbon nanotube aggregate is in the range of more than 100 nm means that the carbon nanotube aggregate has voids of a certain size between the CNTs and the CNTs are excessively overcrowded. It means that it is not in an aggregated state. The upper limit of 400 nm is the measurement limit of the measuring device (BELSORP-mini II) used in the examples.
　ここで、分散性を更に高める観点から、ＣＮＴ集合体の微分細孔容量分布における最大
のピークにおける微分細孔容量の値が、２ｃｍ3／ｇ以上であることが好ましい。 Here, from the viewpoint of further enhancing the dispersibility, the value of the differential pore volume at the maximum peak in the differential pore volume distribution of the CNT aggregate is preferably 2 cm 3 /g or more.
－条件（３）－
　かかる条件の充足性は、下記の要領で判定することができる。
　まず、判定対象であるＣＮＴ集合体を、電子顕微鏡（例えば、電解放射走査型電子顕微鏡）を用いて拡大観察（例えば、１万倍）して、１ｃｍ四方の視野で電子顕微鏡画像を複数枚（例えば、１０枚）取得する。得られた複数枚の電子顕微鏡画像について、高速フーリエ変換（ＦＦＴ）処理を行い、二次元空間周波数スペクトルを得る。複数枚の電子顕微鏡画像のそれぞれについて得られた二次元空間周波数スペクトルを二値化処理して、最も高周波数側に出るピーク位置の平均値を求める。得られたピーク位置の平均値が１μｍ-1以上１００μｍ-1以下の範囲内である場合には、条件（３）を満たすとして判定した。ここで、前記の判定において用いる「ピーク」としては、孤立点の抽出処理（即ち、孤立点除去の逆操作）を実施して得られた明確なピークを用いるものとする。したがって、孤立点の抽出処理を実施した際に１μｍ-1以上１００μｍ-1以下の範囲内にて明確なピークが得られない場合には、条件（３）は満たさないものとして判定する。 -Condition (3)-
The sufficiency of such conditions can be determined in the following manner.
First, the CNT aggregate to be determined is magnified (e.g., 10,000 times) using an electron microscope (e.g., field emission scanning electron microscope), and a plurality of electron microscope images ( For example, 10 sheets) are acquired. A plurality of electron microscope images obtained are subjected to fast Fourier transform (FFT) processing to obtain a two-dimensional spatial frequency spectrum. A two-dimensional spatial frequency spectrum obtained for each of a plurality of electron microscope images is binarized to obtain an average value of peak positions appearing on the highest frequency side. When the average value of the obtained peak positions was within the range of 1 μm −1 or more and 100 μm −1 or less, it was determined that the condition (3) was satisfied. Here, as the "peak" used in the above determination, a clear peak obtained by executing the isolated point extraction process (that is, the inverse operation of the isolated point removal) is used. Therefore, if a clear peak is not obtained within the range of 1 μm −1 to 100 μm −1 when performing the isolated point extraction process, it is determined that the condition (3) is not satisfied.
　ここで、分散性を更に高める観点から、二次元空間周波数スペクトルのピークが、２．６μｍ-1以上１００μｍ-1以下の範囲に存在することが好ましい。 Here, from the viewpoint of further enhancing dispersibility, it is preferable that the peak of the two-dimensional spatial frequency spectrum exists in the range of 2.6 μm −1 or more and 100 μm −1 or less.
　分散性を更に高める観点から、本発明のカーボンナノチューブ集合体は、前記（１）～（３）の条件のうちを少なくとも２つを満たすことが好ましく、（１）～（３）の条件全てを満たすことがより好ましい。 From the viewpoint of further improving the dispersibility, the aggregate of carbon nanotubes of the present invention preferably satisfies at least two of the conditions (1) to (3), and satisfies all the conditions (1) to (3). It is more preferable to satisfy
－第２の態様に係るＣＮＴ集合体の性状－
　第２の態様に係るＣＮＴ集合体は、例えば以下の性状を有していることが好ましい。
　ＣＮＴ集合体は、ＢＥＴ法による全比表面積が、好ましくは６００ｍ2／ｇ以上、より好ましくは８００ｍ2／ｇ以上であり、好ましくは２６００ｍ2／ｇ以下、より好ましくは１４００ｍ2／ｇ以下である。さらに開口処理したものにあっては、１３００ｍ2／ｇ以上であることが好ましい。高い比表面積を有するＣＮＴ集合体は、集合体を構成するＣＮＴ同士に隙間があり、過度にＣＮＴがバンドル化していない。そのため、個々のＣＮＴ同士が緩やかに結合しており、容易に分散させることが可能になる。そして、ＣＮＴ集合体の比表面積が６００ｍ2／ｇ以上であれば、ＣＮＴ集合体のラジカル捕捉能を高めて、エラストマー組成物の耐熱性を更に向上させることができる。ＣＮＴ集合体は、単層ＣＮＴを主として、機能を損なわない程度に、２層ＣＮＴと多層ＣＮＴを含んでもよい。 -Properties of CNT aggregate according to the second aspect-
The CNT aggregate according to the second aspect preferably has, for example, the following properties.
The CNT aggregate preferably has a total specific surface area of 600 m 2 /g or more, more preferably 800 m 2 /g or more, and preferably 2600 m 2 /g or less, more preferably 1400 m 2 /g or less, as determined by the BET method. . Furthermore, it is preferable that the surface area is 1,300 m 2 /g or more for those subjected to the opening treatment. A CNT aggregate having a high specific surface area has gaps between CNTs constituting the aggregate, and the CNTs are not excessively bundled. Therefore, the individual CNTs are loosely bound to each other and can be easily dispersed. If the specific surface area of the CNT aggregate is 600 m 2 /g or more, the radical scavenging ability of the CNT aggregate can be enhanced, and the heat resistance of the elastomer composition can be further improved. The CNT aggregate is mainly composed of single-walled CNTs, and may include double-walled CNTs and multi-walled CNTs to the extent that the functions are not impaired.
　また、後述のＣＮＴの製造方法により担体を用いてＣＮＴを製造した場合、当該担体表面からの、ＣＮＴ集合体を構成するＣＮＴの平均高さは、１０μｍ以上１０ｃｍ以下であることが好ましく、１００μｍ以上２ｃｍ以下であることがより好ましい。ＣＮＴ集合体を構成するＣＮＴの平均高さが１０μｍ以上あると、隣接するＣＮＴバンドルとの凝集を防ぎ、容易に分散させることが可能になる。ＣＮＴ集合体を構成するＣＮＴの平均高さが１００μｍ以上であれば、ＣＮＴ同士のネットワークを形成し易くなり、導電性または機械強度が必要とされる用途において好適に用いることができる。ＣＮＴ集合体を構成するＣＮＴの平均高さが１０ｃｍ以下であると、生成を短時間で行なえるため炭素系不純物の付着を抑制でき比表面積を向上できる。ＣＮＴ集合体を構成するＣＮＴの平均高さが２ｃｍ以下であればより容易に分散させることが可能になる。なお、ＣＮＴの平均高さは、走査型電子顕微鏡（ＳＥＭ）を用いて無作為に選択したＣＮＴ１００本の高さを測定して求めることができる。 In addition, when CNTs are produced using a carrier by the CNT production method described below, the average height of the CNTs constituting the CNT aggregate from the carrier surface is preferably 10 μm or more and 10 cm or less, and 100 μm or more. It is more preferably 2 cm or less. When the average height of the CNTs constituting the CNT aggregate is 10 μm or more, aggregation with adjacent CNT bundles can be prevented and the CNTs can be easily dispersed. If the average height of the CNTs constituting the CNT aggregate is 100 μm or more, it becomes easy to form a network between CNTs, and the CNTs can be suitably used in applications requiring electrical conductivity or mechanical strength. When the average height of the CNTs forming the CNT aggregate is 10 cm or less, the formation can be performed in a short time, so that the adhesion of carbon-based impurities can be suppressed and the specific surface area can be improved. If the average height of the CNTs constituting the CNT aggregate is 2 cm or less, the CNTs can be dispersed more easily. The average height of CNTs can be obtained by measuring the height of 100 randomly selected CNTs using a scanning electron microscope (SEM).
　ＣＮＴ集合体のタップかさ密度は、０．００１ｇ／ｃｍ3以上０．２ｇ／ｃｍ3以下であることが好ましい。このような密度範囲にあるＣＮＴ集合体は、ＣＮＴ同士の結びつきが過度に強まらないため、分散性に優れており、様々な形状に成形加工することが可能である。ＣＮＴ集合体のタップかさ密度が０．２ｇ／ｃｍ3以下であれば、ＣＮＴ同士の結びつきが弱くなるので、ＣＮＴ集合体を溶媒などに撹拌した際に、均質に分散させることが容易になる。また、ＣＮＴ集合体のタップかさ密度が０．００１ｇ／ｃｍ3以上であれば、ＣＮＴ集合体の一体性が向上されハンドリングが容易になる。タップかさ密度とは、粉体状のＣＮＴ集合体を容器に充填した後、タッピングまたは振動等により粉体粒子間の空隙を減少させ、密充填させた状態での見かけかさ密度である。 The tap bulk density of the CNT aggregate is preferably 0.001 g/cm 3 or more and 0.2 g/cm 3 or less. A CNT aggregate having such a density range does not excessively strengthen the bonds between CNTs, so that it is excellent in dispersibility and can be molded into various shapes. If the tapped bulk density of the CNT aggregate is 0.2 g/cm 3 or less, the bonds between the CNTs become weak, so that when the CNT aggregate is stirred in a solvent or the like, it becomes easy to uniformly disperse it. Further, when the tap bulk density of the CNT aggregate is 0.001 g/cm 3 or more, the integrity of the CNT aggregate is improved and handling is facilitated. The tapped bulk density is the apparent bulk density in a state in which the powdery CNT aggregates are filled in a container, and then the gaps between the powder particles are reduced by tapping or vibration to close-pack.
　さらに、ＣＮＴ集合体を構成するＣＮＴの平均直径は、０．５ｎｍ以上であることが好ましく、１．０ｎｍ以上であることが更に好ましく、１５．０ｎｍ以下であることが好ましく、１０．０ｎｍ以下であることがより好ましく、５．０ｎｍ以下であることが更に好ましい。ＣＮＴの平均直径が１．０ｎｍ以上であれば、ＣＮＴ同士のバンドル化が低減でき、高い比表面積を維持できる。ＣＮＴの平均直径が５．０ｎｍ以下であれば、多層ＣＮＴ比率を低減でき、高い比表面積を維持することができる。ここで、ＣＮＴ集合体を構成するＣＮＴの平均直径は、透過型電子顕微鏡（ＴＥＭ）を用いて無作為に選択したＣＮＴ１００本の直径（外径）を測定して求めることができる。ＣＮＴの平均直径は、ＣＮＴの製造方法や製造条件を変更することにより調整してもよいし、異なる製法で得られたＣＮＴを複数種類組み合わせることにより調整してもよい。 Furthermore, the average diameter of the CNTs constituting the CNT aggregate is preferably 0.5 nm or more, more preferably 1.0 nm or more, preferably 15.0 nm or less, and preferably 10.0 nm or less. It is more preferable to have a thickness of 5.0 nm or less. If the average diameter of CNTs is 1.0 nm or more, bundling of CNTs can be reduced and a high specific surface area can be maintained. If the average diameter of CNTs is 5.0 nm or less, the multilayer CNT ratio can be reduced and a high specific surface area can be maintained. Here, the average diameter of CNTs constituting the CNT aggregate can be obtained by measuring the diameter (outer diameter) of 100 randomly selected CNTs using a transmission electron microscope (TEM). The average diameter of CNTs may be adjusted by changing the production method and production conditions of CNTs, or by combining multiple types of CNTs obtained by different production methods.
　ＣＮＴ集合体のＧ／Ｄ比は１以上５０以下であることが好ましい。Ｇ／Ｄ比が１に満たないＣＮＴ集合体は、単層ＣＮＴの結晶性が低く、アモルファスカーボンなどの汚れが多い上、多層ＣＮＴの含有量が多いことが考えられる。反対にＧ／Ｄ比が５０を超えるＣＮＴ集合体は直線性が高く、ＣＮＴが隙間の少ないバンドルを形成しやすく、比表面積が減少する可能性がある。Ｇ／Ｄ比とはＣＮＴの品質を評価するのに一般的に用いられている指標である。ラマン分光装置によって測定されるＣＮＴのラマンスペクトルには、Ｇバンド（１６００ｃｍ-1付近）とＤバンド（１３５０ｃｍ-1付近）と呼ばれる振動モードが観測される。ＧバンドはＣＮＴの円筒面であるグラファイトの六方格子構造由来の振動モードであり、Ｄバンドは非晶箇所に由来する振動モードである。よって、ＧバンドとＤバンドのピーク強度比（Ｇ／Ｄ比）が高いものほど、結晶性（直線性）の高いＣＮＴと評価できる。 The G/D ratio of the CNT aggregate is preferably 1 or more and 50 or less. A CNT aggregate with a G/D ratio of less than 1 is considered to have low crystallinity of single-walled CNTs, a large amount of dirt such as amorphous carbon, and a large content of multi-walled CNTs. On the contrary, CNT aggregates with a G/D ratio of more than 50 have high linearity, CNTs tend to form bundles with few gaps, and the specific surface area may decrease. The G/D ratio is an index commonly used to evaluate the quality of CNTs. Vibrational modes called G band (near 1600 cm −1 ) and D band (near 1350 cm −1 ) are observed in the Raman spectrum of CNTs measured by a Raman spectrometer. The G band is a vibrational mode derived from the hexagonal lattice structure of graphite, which is the cylindrical surface of CNT, and the D band is a vibrational mode derived from amorphous sites. Therefore, a CNT with a higher peak intensity ratio (G/D ratio) between the G band and the D band can be evaluated as having higher crystallinity (linearity).
　ＣＮＴ集合体の炭素純度は、９０質量％であることが好ましく、９４質量％以上であることがより好ましく、９６質量％以上であることが更に好ましく、９８質量％以上であることが一層好ましく、９９質量％以上であることがより一層好ましい。ＣＮＴ集合体の炭素純度が上記下限以上であれば、ＣＮＴ集合体のラジカル捕捉能を高めて、エラストマー組成物の耐熱性を更に向上させることができる。
　なお、ＣＮＴの炭素純度の上限は、特に限定されないが、例えば、９９．９９９９質量％以下である。 The carbon purity of the CNT aggregate is preferably 90% by mass, more preferably 94% by mass or more, still more preferably 96% by mass or more, even more preferably 98% by mass or more, More preferably, it is 99% by mass or more. If the carbon purity of the CNT aggregates is equal to or higher than the above lower limit, the radical scavenging ability of the CNT aggregates can be enhanced, and the heat resistance of the elastomer composition can be further improved.
Although the upper limit of the carbon purity of CNT is not particularly limited, it is, for example, 99.9999% by mass or less.
　第２の態様に係るカーボンナノチューブ集合体は、流動層法、移動層法及び固定層法等の既知の方途に従うＣＮＴ合成工程を用いて製造できる。ここで、流動層法とは、ＣＮＴを合成するための触媒を担持した粒状の担体（以下、粒状触媒担持体とも称する）を流動化させながら、ＣＮＴを合成する合成方法を意味する。また、移動層法及び固定層法とは、触媒を担持した担体（粒子状担体或いは板状担体）を流動させることなく、ＣＮＴを合成する合成方法を意味する。 The carbon nanotube aggregate according to the second aspect can be produced using a CNT synthesis process according to known methods such as the fluidized bed method, moving bed method and fixed bed method. Here, the fluidized bed method means a synthesis method for synthesizing CNTs while fluidizing a granular carrier supporting a catalyst for synthesizing CNTs (hereinafter also referred to as a granular catalyst carrier). Further, the moving bed method and the fixed bed method mean synthesis methods for synthesizing CNTs without fluidizing a carrier (particulate carrier or plate-shaped carrier) supporting a catalyst.
＜＜ＣＮＴ含有量＞＞
　本発明のエラストマー組成物中のＣＮＴの含有量は、フッ素含有エラストマー１００質量部に対して、０．１質量部以上であることが好ましく、０．５質量部以上であることがより好ましく、１質量部以上含むことが更に好ましく、１．５質量部以上であることが一層好ましく、２質量部以上であることがより一層好ましく、１０質量部以下であることが好ましく、８質量部以下であることがより好ましく、６質量部以下であることが更に好ましく、５質量部以下であることが一層好ましく、４質量部以下であることがより一層好ましい。エラストマー組成物中のＣＮＴの含有量が上記所定の範囲内であれば、エラストマー組成物中にＣＮＴを良好に分散させることで、エラストマー組成物の耐熱性を更に向上させることができる。
　なお、ＣＮＴとしては単層ＣＮＴ（ＳＷＣＮＴ）と多層ＣＮＴ（ＭＷＣＮＴ）とを併用することができる。そして、ＣＮＴとして単層ＣＮＴと多層ＣＮＴとを併用した場合、上述したエラストマー組成物中のＣＮＴの含有量は、単層ＣＮＴと多層ＣＮＴとの合計含有量を意味する。
　また、ＣＮＴが単層ＣＮＴである場合、エラストマー組成物中の単層ＣＮＴの含有量は、フッ素含有エラストマー１００質量部に対して、０．１質量部以上２質量部以下であることが好ましい。
　さらに、ＣＮＴが多層ＣＮＴである場合、エラストマー組成物中の多層ＣＮＴの含有量は、フッ素含有エラストマー１００質量部に対して、０．５質量部以上８質量部以下であることが好ましい。 <<CNT content>>
The content of CNTs in the elastomer composition of the present invention is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, with respect to 100 parts by mass of the fluorine-containing elastomer. More preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, preferably 10 parts by mass or less, 8 parts by mass or less is more preferably 6 parts by mass or less, even more preferably 5 parts by mass or less, and even more preferably 4 parts by mass or less. If the content of CNTs in the elastomer composition is within the above-specified range, the heat resistance of the elastomer composition can be further improved by good dispersion of the CNTs in the elastomer composition.
In addition, as CNT, a single wall CNT (SWCNT) and a multilayer CNT (MWCNT) can be used together. When both single-walled CNTs and multi-walled CNTs are used as CNTs, the content of CNTs in the above elastomer composition means the total content of single-walled CNTs and multi-walled CNTs.
When the CNTs are single-walled CNTs, the content of the single-walled CNTs in the elastomer composition is preferably 0.1 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the fluorine-containing elastomer.
Furthermore, when the CNTs are multilayer CNTs, the content of the multilayer CNTs in the elastomer composition is preferably 0.5 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the fluorine-containing elastomer.
＜架橋剤＞
　本発明のエラストマー組成物は、任意で、架橋剤を更に含んでいてもよい。即ち、本発明のエラストマー組成物は、上述した（未架橋の）フッ素含有エラストマーおよびＣＮＴに加えて、架橋剤を更に含む架橋性組成物であってもよい。
　エラストマー組成物に含まれ得る架橋剤としては、特に限定されないが、エラストマー組成物中のフッ素含有エラストマーを架橋可能な既知の架橋剤を用いることができる。このような架橋剤としては、例えば、パーオキサイド系架橋剤、ビスフェノール系架橋剤、ジアミン系架橋剤、トリアジン系架橋剤、オキサゾール系架橋剤、イミダゾール系架橋剤、チアゾール系架橋剤が挙げられる。なお、架橋剤は、１種単独で、又は、２種以上を混合して用いることができる。また、エラストマー組成物中の架橋剤の含有量は、特に限定されず、既知のエラストマー組成物中において通常使用する量とすることができる。 <Crosslinking agent>
The elastomeric composition of the invention may optionally further comprise a cross-linking agent. That is, the elastomer composition of the present invention may be a crosslinkable composition further comprising a crosslinking agent in addition to the (uncrosslinked) fluorine-containing elastomer and CNTs described above.
The cross-linking agent that can be contained in the elastomer composition is not particularly limited, but any known cross-linking agent capable of cross-linking the fluorine-containing elastomer in the elastomer composition can be used. Examples of such cross-linking agents include peroxide-based cross-linking agents, bisphenol-based cross-linking agents, diamine-based cross-linking agents, triazine-based cross-linking agents, oxazole-based cross-linking agents, imidazole-based cross-linking agents, and thiazole-based cross-linking agents. In addition, a crosslinking agent can be used individually by 1 type or in mixture of 2 or more types. Moreover, the content of the cross-linking agent in the elastomer composition is not particularly limited, and may be the amount normally used in known elastomer compositions.
　なお、架橋剤を用いる場合、本発明のエラストマー組成物は、フッ素含有エラストマーが架橋剤によって架橋されていてもよい。即ち、本発明のエラストマー組成物は、上述したフッ素含有エラストマー、ＣＮＴ、および架橋剤を少なくとも含む架橋性プレ組成物を架橋して得られる架橋物であってもよい。 When a cross-linking agent is used, the fluorine-containing elastomer in the elastomer composition of the present invention may be cross-linked by the cross-linking agent. That is, the elastomer composition of the present invention may be a cross-linked product obtained by cross-linking a cross-linkable pre-composition containing at least the fluorine-containing elastomer, CNTs and a cross-linking agent.
＜添加剤＞
　エラストマー組成物に含まれ得る添加剤としては、特に限定されることなく、分散剤、酸化防止剤、熱安定剤、光安定剤、紫外線吸収剤、顔料、着色剤、発泡剤、帯電防止剤、難燃剤、滑剤、軟化剤、粘着付与剤、可塑剤、離型剤、防臭剤、香料などを挙げることができる。より具体的な添加剤としては、例えば、カーボンブラック、シリカ、タルク、硫酸バリウム、炭酸カルシウム、クレー、酸化マグネシウム、水酸化カルシウムなどが挙げられる。なお、添加剤は、１種単独で、又は、２種以上を混合して用いることができる。またエラストマー組成物中の添加剤の含有量は、特に限定されず、既知のエラストマー組成物中において通常使用する量とすることができる。 <Additive>
Additives that may be included in the elastomer composition include, but are not limited to, dispersants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, pigments, colorants, foaming agents, antistatic agents, Flame retardants, lubricants, softeners, tackifiers, plasticizers, release agents, deodorants, perfumes, and the like can be mentioned. Examples of more specific additives include carbon black, silica, talc, barium sulfate, calcium carbonate, clay, magnesium oxide and calcium hydroxide. In addition, an additive can be used individually by 1 type or in mixture of 2 or more types. Moreover, the content of the additive in the elastomer composition is not particularly limited, and may be the amount normally used in known elastomer compositions.
＜エラストマー組成物の製造方法＞
　本発明のエラストマー組成物を製造する方法は、特に限定されることはない。
　本発明のエラストマー組成物の製造方法の一例は、フッ素含有エラストマーと、カーボンナノチューブと、フッ素含有エラストマーを溶解可能な溶剤と、を混合分散処理してカーボンナノチューブ分散液を得る分散工程と、得られたカーボンナノチューブ分散液から前記溶剤を除去して乾燥物を得る乾燥工程を備える。また、本発明のエラストマー組成物の製造方法の一例は、上記乾燥工程の後、乾燥物に対して、架橋剤および添加剤などを更に添加して混合し、架橋性プレ組成物を得る混練工程、および、架橋性プレ組成物を架橋してエラストマー組成物としての架橋物を得る架橋工程を更に含んでいてもよい。さらに、本発明のエラストマー組成物の製造方法は、エラストマー組成物としての架橋物の形状を固定化した成形体を得る成形工程を更に含んでいてもよい。 <Method for producing elastomer composition>
The method for producing the elastomer composition of the present invention is not particularly limited.
An example of the method for producing the elastomer composition of the present invention includes a dispersing step of obtaining a carbon nanotube dispersion by mixing and dispersing a fluorine-containing elastomer, carbon nanotubes, and a solvent capable of dissolving the fluorine-containing elastomer, and and a drying step of removing the solvent from the carbon nanotube dispersion to obtain a dried product. An example of the method for producing the elastomer composition of the present invention is a kneading step in which a cross-linking agent, an additive, etc. are further added to the dried product after the drying step and mixed to obtain a cross-linkable pre-composition. and a cross-linking step of cross-linking the cross-linkable pre-composition to obtain a cross-linked product as the elastomer composition. Furthermore, the method for producing the elastomer composition of the present invention may further include a molding step of obtaining a molded article in which the shape of the crosslinked product as the elastomer composition is fixed.
＜＜分散工程＞＞
　分散工程では、フッ素含有エラストマーと、カーボンナノチューブと、フッ素含有エラストマーを溶解可能な溶剤と、を混合分散処理してカーボンナノチューブ分散液を得る。得られたカーボンナノチューブ分散液は、フッ素含有エラストマーが溶剤に溶解したエラストマー溶液と、前記エラストマー溶液に分散したカーボンナノチューブ（またはカーボンナノチューブ集合体）とを含む。 <<Dispersion process>>
In the dispersion step, the fluorine-containing elastomer, carbon nanotubes, and a solvent capable of dissolving the fluorine-containing elastomer are mixed and dispersed to obtain a carbon nanotube dispersion. The resulting carbon nanotube dispersion contains an elastomer solution in which a fluorine-containing elastomer is dissolved in a solvent, and carbon nanotubes (or aggregates of carbon nanotubes) dispersed in the elastomer solution.
　溶剤としては、フッ素含有エラストマーを溶解可能な溶剤であれば特に限定されない。このような溶剤として、例えば、メチルエチルケトンやアセトンなどのケトン類、テトラヒドロフランなどのエーテル類、フッ素系溶剤が挙げられ、この中でもフッ素系溶剤が好ましい。 The solvent is not particularly limited as long as it can dissolve the fluorine-containing elastomer. Examples of such solvents include ketones such as methyl ethyl ketone and acetone, ethers such as tetrahydrofuran, and fluorine-based solvents. Among these, fluorine-based solvents are preferred.
　フッ素系溶剤としては、ペルフルオロ炭化水素基を有する溶剤を用いることができる。ペルフルオロ炭化水素基は、鎖式のペルフルオロ炭化水素基であってもよく、環式のペルフルオロ炭化水素基であってもよい。 A solvent having a perfluorohydrocarbon group can be used as the fluorine-based solvent. The perfluorohydrocarbon group may be a chain perfluorohydrocarbon group or a cyclic perfluorohydrocarbon group.
　鎖式のペルフルオロ炭化水素基は、直鎖状であってもよく、分岐鎖状であってもよい。鎖式のペルフルオロ炭化水素基としては、ペルフルオロアルキル基、ペルフルオロアルキレン基、ペルフルオロビニルアルキル基、ペルフルオロビニルアルキレン基等が例示される。ペルフルオロ炭化水素基における最も炭素数の多いペルフルオロ炭化水素基の炭素数は、３～７である。前記炭素数が３以上であると、フッ素系溶剤に対するフッ素含有エラストマーの溶解性が優れる。前記炭素数が７以下であると、フッ素系溶剤を入手しやすい。また、前記炭素数が６以下であると、フッ素系溶剤の沸点が低くなる傾向になり、除去しやすい。 The chain-type perfluorohydrocarbon group may be linear or branched. Examples of chain perfluorohydrocarbon groups include perfluoroalkyl groups, perfluoroalkylene groups, perfluorovinylalkyl groups, and perfluorovinylalkylene groups. The perfluorohydrocarbon group having the largest number of carbon atoms in the perfluorohydrocarbon group has 3 to 7 carbon atoms. When the number of carbon atoms is 3 or more, the solubility of the fluorine-containing elastomer in fluorine-based solvents is excellent. When the number of carbon atoms is 7 or less, the fluorine-based solvent is easily available. Further, when the number of carbon atoms is 6 or less, the boiling point of the fluorine-based solvent tends to be low, making it easy to remove.
　フッ素系溶剤の沸点は、５０～１６０℃であることが好ましい。フッ素系溶剤の沸点が５０℃以上であると、分散処理を安定して行うことができる。フッ素系溶剤の沸点が１６０℃以下であると、フッ素系溶剤を除去しやすい。フッ素系溶剤としては、窒素原子を有する含フッ素化合物、ハイドロフルオロカーボン、およびハイドロフルオロエーテルからなる群より選ばれる少なくとも一つが好ましい。フッ素系溶剤が窒素原子を有する含フッ素化合物、ハイドロフルオロカーボン、およびハイドロフルオロエーテルからなる群より選ばれる少なくとも一つであると、フッ素系溶剤へのフッ素含有エラストマーの溶解性が優れる傾向にある。なお、溶剤は、１種単独で使用してもよいし、２種類以上を任意の比率で組み合わせて用いてもよい。 The boiling point of the fluorinated solvent is preferably 50 to 160°C. When the boiling point of the fluorine-based solvent is 50° C. or higher, the dispersion treatment can be stably performed. If the boiling point of the fluorine-based solvent is 160° C. or lower, the fluorine-based solvent can be easily removed. At least one selected from the group consisting of fluorine-containing compounds having a nitrogen atom, hydrofluorocarbons, and hydrofluoroethers is preferable as the fluorine-based solvent. When the fluorine-containing solvent is at least one selected from the group consisting of nitrogen-containing fluorine-containing compounds, hydrofluorocarbons, and hydrofluoroethers, the fluorine-containing elastomer tends to have excellent solubility in the fluorine-containing solvent. In addition, a solvent may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.
　窒素原子を有するフッ素系溶剤の具体例としては、３Ｍ社製のフロリナート（登録商標）ＦＣ－７７０が例示される。
　ハイドロフルオロカーボンの具体例としては、１，１，１，２，２，３，３，４，４－ノナフルオロヘキサン、１，１，１，２，２，３，３，４，４，５，５，６，６－トリデカフルオロヘキサン、１，１，１，２，２，３，３，４，４，５，５，６，６－トリデカフルオロオクタンが例示される。１，１，１，２，２，３，３，４，４，５，５，６，６－トリデカフルオロヘキサンの市販品としてはＡＧＣ社製のアサヒクリン（登録商標）ＡＣ－２０００、１，１，１，２，２，３，３，４，４，５，５，６，６－トリデカフルオロオクタンの市販品としてはＡＧＣ社製のアサヒクリン（登録商標）ＡＣ－６０００が例示される。
　ハイドロフルオロエーテルの具体例としては、３Ｍ社製のノベック（登録商標）７３００が例示される。 A specific example of the fluorinated solvent having a nitrogen atom is Fluorinert (registered trademark) FC-770 manufactured by 3M Company.
Specific examples of hydrofluorocarbons include 1,1,1,2,2,3,3,4,4-nonafluorohexane, 1,1,1,2,2,3,3,4,4,5, Examples include 5,6,6-tridecafluorohexane and 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane. Commercial products of 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane include Asahiklin (registered trademark) AC-2000, 1 manufactured by AGC. , 1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane is exemplified by Asahiklin (registered trademark) AC-6000 manufactured by AGC. be.
Specific examples of hydrofluoroethers include Novec (registered trademark) 7300 manufactured by 3M.
　そして、分散工程は、例えば、フッ素含有エラストマーを溶剤に溶解させたエラストマー溶液を得る溶解ステップと、得られたエラストマー溶液中にカーボンナノチューブを混合して分散処理する分散処理ステップと、を備える。 The dispersing step includes, for example, a dissolving step of dissolving the fluorine-containing elastomer in a solvent to obtain an elastomer solution, and a dispersing step of mixing carbon nanotubes in the obtained elastomer solution and dispersing the carbon nanotubes.
　溶解ステップは、フッ素含有エラストマーを溶剤に溶解すればよく、既知の手法により実施することができる。また、分散処理ステップは、エラストマー溶液中にＣＮＴを分散させることができればよく、既知の分散処理を用いることができる。このような分散処理としては、例えば、ずり応力による分散処理、衝突エネルギーによる分散処理、キャビテーション効果が得られる分散処理を挙げることができる。このような分散処理によれば、比較的簡便に分散処理を実施することができる。 The dissolution step may be performed by dissolving the fluorine-containing elastomer in a solvent, and can be performed by a known method. Further, the dispersion treatment step may be any known dispersion treatment as long as the CNTs can be dispersed in the elastomer solution. Examples of such dispersion treatment include dispersion treatment by shear stress, dispersion treatment by collision energy, and dispersion treatment that produces a cavitation effect. According to such distributed processing, distributed processing can be performed relatively easily.
　ずり応力による分散処理に使用し得る装置としては、２本ロールミルや３本ロールミル等が挙げられる。衝突エネルギーによる分散処理に使用し得る装置としては、ビーズミル、ローター／ステーター型分散機等が挙げられる。キャビテーション効果が得られる分散処理に使用し得る装置としては、ジェットミル、超音波分散機等が挙げられる。分散処理の条件は特に限定されず、例えば上述した装置における通常の分散条件の範囲内で適宜設定することができる。 Devices that can be used for dispersion treatment using shear stress include a two-roll mill and a three-roll mill. Apparatuses that can be used for dispersion treatment by collision energy include bead mills, rotor/stator type dispersers, and the like. A jet mill, an ultrasonic disperser, and the like can be used as devices that can be used for the dispersion treatment to obtain the cavitation effect. The conditions for the dispersion treatment are not particularly limited, and can be appropriately set within the range of normal dispersion conditions in the apparatus described above, for example.
　中でも、得られるＣＮＴ分散液中にＣＮＴを良好に分散させて、製造されるエラストマー組成物の耐熱性を更に向上させる観点から、分散処理においては、ビーズミルと超音波分散分散機とを併用することが好ましい。
　例えば、エラストマー溶液とカーボンナノチューブとを混合して得られたスラリーを、ホールディングタンクとビーズミルと超音波分散機とを接続してなる循環系において循環させることが好ましい。
　ビーズミルの周速（回転数）は、適宜調整可能であるが、例えば、４ｍ／ｓ以上であることが好ましく、５ｍ／ｓ以上であることがより好ましく、６ｍ／ｓ以上であることが更に好ましく、１５ｍ／ｓ以下であることが好ましく、１２ｍ／ｓ以下であることがより好ましく、９ｍ／ｓ以下であることが更に好ましい。ビーズミルの周速が上記所定の範囲内であれば、得られるＣＮＴ分散液中にＣＮＴを更に良好に分散させて、製造されるエラストマー組成物の耐熱性を一層向上させることができる。 Above all, from the viewpoint of better dispersing the CNTs in the resulting CNT dispersion and further improving the heat resistance of the produced elastomer composition, in the dispersion treatment, a bead mill and an ultrasonic dispersion disperser are used in combination. is preferred.
For example, it is preferable to circulate the slurry obtained by mixing the elastomer solution and the carbon nanotubes in a circulation system formed by connecting a holding tank, a bead mill and an ultrasonic disperser.
The peripheral speed (rotational speed) of the bead mill can be adjusted as appropriate, but is preferably, for example, 4 m/s or more, more preferably 5 m/s or more, and even more preferably 6 m/s or more. , is preferably 15 m/s or less, more preferably 12 m/s or less, and even more preferably 9 m/s or less. If the peripheral speed of the bead mill is within the above-specified range, the CNTs can be dispersed more favorably in the obtained CNT dispersion, and the heat resistance of the produced elastomer composition can be further improved.
＜＜乾燥工程＞＞
　乾燥工程では、分散工程で得られたＣＮＴ分散液から溶剤を除去して乾燥物を得る。
　乾燥工程は、ＣＮＴ分散液から溶剤を除去できればよく、例えば、凝固法、キャスト法、および乾燥法などの既知の方法を用いることができる。
　なお、乾燥工程で得られた乾燥物を本発明のエラストマー組成物として用いてもよい。 <<Drying process>>
In the drying step, the solvent is removed from the CNT dispersion obtained in the dispersion step to obtain a dried product.
The drying step can remove the solvent from the CNT dispersion, and known methods such as coagulation, casting, and drying can be used.
A dried product obtained in the drying step may be used as the elastomer composition of the present invention.
＜＜混練工程＞＞
　混練工程では、乾燥物に対して、架橋剤および添加剤などを更に添加して混合し、架橋性プレ組成物を得る。
　混練工程は、例えば、ミキサー、一軸混練機、二軸混練機、ロール、加圧ニーダー、ブラベンダー（登録商標）、押出機などを用いて行うことができる。
　なお、混練工程で得られた架橋性プレ組成物を本発明のエラストマー組成物として用いてもよい。 << Kneading process >>
In the kneading step, a cross-linkable pre-composition is obtained by adding a cross-linking agent, an additive, and the like to the dried product and mixing them.
The kneading step can be performed using, for example, a mixer, a single-screw kneader, a twin-screw kneader, rolls, a pressure kneader, Brabender (registered trademark), an extruder, or the like.
The crosslinkable pre-composition obtained in the kneading step may also be used as the elastomer composition of the present invention.
＜＜架橋工程＞＞
　架橋工程では、架橋性プレ組成物を架橋してエラストマー組成物としての架橋物を得る。架橋工程は、例えば、架橋性プレ組成物を所望の形状の金型に投入して加熱することで、プレス成形と架橋工程とを同時に行うことができる。また、架橋性プレ組成物を所望の形状の金型に投入して加熱することで、プレス成形と一次架橋とを同時に行なった後に、得られた一次架橋物をギヤーオーブン等の加熱装置により再度加熱することで二次架橋を行うこともできる。なお、架橋反応の温度および時間等の条件は、適宜設定できる。 <<crosslinking process>>
In the cross-linking step, the cross-linkable pre-composition is cross-linked to obtain a cross-linked product as an elastomer composition. In the cross-linking step, for example, the press molding and the cross-linking step can be performed at the same time by putting the cross-linkable pre-composition into a mold having a desired shape and heating it. Alternatively, the crosslinkable pre-composition is put into a mold of a desired shape and heated to simultaneously perform press molding and primary crosslinking, and then the obtained primary crosslinked product is heated again with a heating device such as a gear oven. Secondary cross-linking can also be performed by heating. Conditions such as the temperature and time of the cross-linking reaction can be appropriately set.
＜＜成形工程＞＞
　成形工程では、エラストマー組成物としての架橋物の形状を固定化した成形体を得る。成形工程は、例えば、射出成形、押出成形、プレス成形、ロール成形などの任意の方法で実施できる。成形工程で得られた成形体は、本発明のエラストマー組成物からなるため、耐熱性に優れている。また、成形工程で得られた成形体は、ＣＮＴがフッ素含有エラストマー中に良好に分散しているため、導電性、熱伝導性、及び強度などの特性に優れる。 <<Molding process>>
In the molding step, a molded article is obtained in which the shape of the crosslinked product as the elastomer composition is fixed. The molding step can be carried out by any method such as injection molding, extrusion molding, press molding, roll molding, and the like. Since the molded article obtained in the molding step is made of the elastomer composition of the present invention, it has excellent heat resistance. In addition, the molded article obtained in the molding process is excellent in properties such as electrical conductivity, thermal conductivity and strength because CNTs are well dispersed in the fluorine-containing elastomer.
＜＜成形体の用途＞＞
　本発明のエラストマー組成物からなる成形体は、例えば、自動車部品、空調機器、制御機器、給水・給湯機器、高温蒸気装置、半導体装置、食品加工処理装置、分析・理化学機器、液体貯蔵装置及び圧力スイッチ装置、ペイント・塗装設備、印刷・塗布設備、ＯＡ機器、燃料電池周辺機器並びに、石油掘削分野及び医療分野などの分野で使用される、高温環境下において高い引張強度及び高い伸びが要求される各種部品として好適に用いることができる。具体的に、成形体は、ホース、シール材、ベルト、防振ゴム、ダイヤフラム、中空ゴム成形体、ロール、チューブなどとして用いることができる。 <<Uses of Molded Body>>
Molded articles made from the elastomer composition of the present invention can be used, for example, in automobile parts, air conditioning equipment, control equipment, water supply/hot water supply equipment, high-temperature steam equipment, semiconductor equipment, food processing equipment, analytical/physical and chemical equipment, liquid storage equipment, and pressure equipment. High tensile strength and high elongation are required in a high temperature environment, used in fields such as switch devices, paint/coating equipment, printing/coating equipment, OA equipment, fuel cell peripheral equipment, oil drilling and medical fields. It can be suitably used as various parts. Specifically, the molded article can be used as a hose, a sealing material, a belt, an anti-vibration rubber, a diaphragm, a hollow rubber molded article, a roll, a tube, and the like.
　ホースとしては、特に限定されず、例えば、燃料ホース、ターボエアーホース、オイルホース、ラジエーターホース、ヒーターホース、ウォーターホース、バキュームブレーキホース、コントロールホース、エアコンホース、ブレーキホース、パワーステアリングホース、エアーホース、マリンホース、ライザー、フローラインなどの各種ホースが挙げることができる。 The hose is not particularly limited, and examples include fuel hose, turbo air hose, oil hose, radiator hose, heater hose, water hose, vacuum brake hose, control hose, air conditioner hose, brake hose, power steering hose, air hose, Various hoses such as marine hoses, risers, and flow lines can be mentioned.
　シール材としては、特に限定されず、例えば、О－リング、パッキン、オイルシール、シャフトシール、ベアリングシール、メカニカルシール、ウェルヘッドシール、電気・電子機器用シール、空気圧機器用シールなどの各種シールが挙げることができる。
　ベルトとしては、特に限定されず、例えば、動力伝達ベルト、搬送ベルトなどの各種ベルトが挙げることができる。
　防振ゴムとしては、特に限定されず、例えば、自動車用防振ゴムなどの各種防振ゴムが挙げることができる。 The sealing material is not particularly limited, and various types of seals such as O-rings, packings, oil seals, shaft seals, bearing seals, mechanical seals, well head seals, seals for electric/electronic devices, and seals for pneumatic devices can be used. can be mentioned.
The belt is not particularly limited, and examples thereof include various belts such as power transmission belts and conveyor belts.
The vibration-isolating rubber is not particularly limited, and examples thereof include various vibration-isolating rubbers such as automotive vibration-isolating rubber.
　ダイヤフラムとしては、特に限定されず、例えば、燃料系、排気系、ブレーキ系、駆動系、点火系などの自動車エンジン用ダイヤフラム；ポンプ用ダイヤフラム；バルブ用ダイヤフラム；フィルタープレス用ダイヤフラム；ブロワー用ダイヤフラム；などの各種ダイヤフラムが挙げることができる。 The diaphragm is not particularly limited, and examples include automobile engine diaphragms such as fuel systems, exhaust systems, brake systems, drive systems, and ignition systems; pump diaphragms; valve diaphragms; filter press diaphragms; blower diaphragms; various diaphragms.
　中空ゴム成形体としては、特に限定されず、例えば、タイヤ製造用ブラダー、タイヤ加硫用ブラダーなどの各種ブラダー；フレキシブルジョイント、エキスパンションジョイントなどの各種ジョイント；ジョイントブーツ、ラックアンドピニオンステアリングブーツ、ピンブーツ、ピストンブーツなどの各種ブーツ；プライマーバルブなどの各種バルブ；等が挙げることができる。 The hollow rubber molding is not particularly limited, and examples include various bladders such as tire manufacturing bladders and tire vulcanizing bladders; various joints such as flexible joints and expansion joints; joint boots, rack and pinion steering boots, pin boots, various boots such as a piston boot; various valves such as a primer valve;
　ロールとしては、特に限定されず、例えば、印刷ロール；塗布ロール；プリンターなどコピー用ロール；等が挙げることができる。 The roll is not particularly limited, and examples include a printing roll; a coating roll; a copying roll such as a printer;
　チューブとしては、特に限定されず、例えば、分析機器類のチューブ；ポンプ、反応器、撹拌機、混合機類のチューブ；プリンターなどインキ用チューブ；半導体製造装置用ポンプなどのチューブ；燃料電池用チューブ；高腐食ガス性を要求されるチューブ；等が挙げることができる。 The tube is not particularly limited, and for example, tubes for analytical instruments; tubes for pumps, reactors, stirrers, and mixers; tubes for ink such as printers; tubes for pumps for semiconductor manufacturing equipment; tubes for fuel cells. a tube that requires high corrosive gas resistance; and the like.
　以下、本発明について実施例に基づき具体的に説明するが、本発明はこれらの実施例に限定されるものではない。なお、以下の説明において、量を表す「％」及び「部」は、特に断らない限り、質量基準である。 The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified.
　本実施例及び比較例において、各種の測定及び評価は、以下の方法に従って実施した。 In the examples and comparative examples, various measurements and evaluations were carried out according to the following methods.
＜カーボンナノチューブの炭素純度＞
　熱重量分析装置（ＴＡインスツルメント社製、製品名「Ｄｉｓｃｏｖｅｒｙ　ＴＧＡ５５００」を用いて、実施例、比較例で用いたカーボンナノチューブ２ｍｇを大気雰囲気下、室温から８００℃まで５℃／ｍｉｎで昇温を行い、８００℃まで昇温により減少した重量（％）を炭素純度として求めた。 <Carbon Purity of Carbon Nanotubes>
Using a thermogravimetric analyzer (manufactured by TA Instruments, product name “Discovery TGA5500”), 2 mg of the carbon nanotubes used in Examples and Comparative Examples were heated from room temperature to 800 ° C. at a rate of 5 ° C./min in an air atmosphere. was performed, and the weight (%) that decreased due to the temperature rising up to 800° C. was obtained as the carbon purity.
＜３７０℃２時間加熱後のラジカル濃度＞
　実施例及び比較例で得られたエラストマー組成物を３７０℃のイナートオーブン（光洋サーモシステム社製、型式「ＩＮＨ－９ＣＤ－Ｓ」）で、大気雰囲気下２時間熱処理することで、熱老化後の架橋ゴムシートを得た。そして、得られた熱老化後のエラストマー組成物について、熱処理から２４時間経過後に、電子スピン共鳴（ＥＳＲ）測定装置を用いて、以下の条件で測定し、ラジカル濃度を求めた。
　　測定装置：日本電子社製ＪＥＳ　ＦＡ２００
　　時定数：０．０３秒
　　測定温度：２３℃
　　マイクロ波強度：１．０ｍＷ
　　変調磁場：０．３ｍＴ
　　掃引範囲：３３６．０±７．５ｍＴ
　　掃引時間：３０秒
　本測定で計測されるラジカルは室温で安定なラジカルの濃度であり、エラストマー組成物を３７０℃で２時間加熱することにより発生するフッ素含有エラストマー由来のラジカルはカーボンナノチューブによって捕捉され、室温で安定なラジカルとして本測定で検出されたと考えることができる。 <Radical concentration after heating at 370°C for 2 hours>
By heat-treating the elastomer compositions obtained in Examples and Comparative Examples in an inert oven (manufactured by Koyo Thermo Systems Co., Ltd., model "INH-9CD-S") at 370° C. for 2 hours in an air atmosphere, the A crosslinked rubber sheet was obtained. Then, after 24 hours from the heat treatment, the obtained elastomer composition after heat aging was measured using an electron spin resonance (ESR) measurement device under the following conditions to determine the radical concentration.
Measuring device: JES FA200 manufactured by JEOL Ltd.
Time constant: 0.03 seconds Measurement temperature: 23°C
Microwave intensity: 1.0mW
Modulation magnetic field: 0.3mT
Sweep range: 336.0±7.5mT
Sweep time: 30 seconds The concentration of radicals measured in this measurement is stable at room temperature, and the fluorine-containing elastomer-derived radicals generated by heating the elastomer composition at 370°C for 2 hours are captured by carbon nanotubes. , can be considered to have been detected in this measurement as radicals that are stable at room temperature.
＜熱老化後の伸び＞
　実施例および比較例で得られたエラストマー組成物としての架橋ゴムシートを、ダンベル試験片状（ＪＩＳ３号）に打ち抜き、試験片を作製した。試験片を３７０℃のオーブン（光洋サーモシステム社製、型式「ＩＮＨ－９ＣＤ－Ｓ」）で、大気下、２時間、熱処理をし、熱老化後の試験片を作製した。熱老化後の試験片について、引張試験機（東洋精機社製、製品名「ストログラフＶＧ」を用い、ＪＩＳ　Ｋ６２５１：２０１０に準拠して、試験温度２３℃、試験湿度５０％、引張速度５００ｍｍ／分の条件で引張試験を行い、試験片が破断するまでの伸びを計測した。伸びの値が大きい程、エラストマー組成物が耐熱性に優れることを示す。 <Elongation after heat aging>
The crosslinked rubber sheets as elastomer compositions obtained in Examples and Comparative Examples were punched into dumbbell test pieces (JIS No. 3) to prepare test pieces. The test piece was heat-treated in an oven (manufactured by Koyo Thermo Systems Co., Ltd., model "INH-9CD-S") at 370° C. for 2 hours in the atmosphere to prepare a test piece after heat aging. For the test piece after heat aging, using a tensile tester (manufactured by Toyo Seiki Co., Ltd., product name "Strograph VG", in accordance with JIS K6251: 2010, test temperature 23 ° C., test humidity 50%, tensile speed 500 mm / A tensile test was carried out under conditions of minutes, and the elongation until the test piece broke was measured.The larger the elongation value, the more excellent the heat resistance of the elastomer composition.
（実施例１）
＜分散工程＞
　溶剤としての１，１，１，２，２，３，４，５，５，５－デカフルオロ－３－メトキシ－４－（トリフルオロメチル）－ペンタン（３Ｍ社製、製品名「ノベック（登録商標）７３００」）１８９９ｇに、フッ素含有エラストマーとしてのＦＦＫＭ（ＡＧＣ社製、商品名「Ａｆｌａｓ　ＰＭ－３０００」）１００部（１００ｇ）を加え、温度２０℃で１２時間撹拌してフッ素含有エラストマーを溶解させて、フッ素含有エラストマー溶液を得た（溶解ステップ）。
　次に、フッ素含有エラストマー溶液に対し、カーボンナノチューブとしてのＳＧＣＮＴ（日本ゼオン社製、製品名「ＺＥＯＮＡＮＯ　ＳＧ１０１」、平均直径：３．５ｎｍ、ＢＥＴ比表面積：１４４９ｍ２／ｇ、ｔ－プロットは上に凸、炭素純度：９９．６％、単層ＣＮＴを主として含む）２部（２ｇ）を加え、撹拌機（ＰＲＩＭＩＸ社製、ラボ・リューション（登録商標）、撹拌部：ホモディスパー）を用い、温度２０℃で３０分間撹拌した。更に、得られたスラリーを、ホールディングタンクとビーズミル（ウィリー・エ・バッコーフェン社製、商品名「ダイノーミル　マルチラボ」、ジルコニアビーズ平均直径：０．６５ｍｍ、周速８ｍ／ｓ）と超音波分散機（ソニックテクノロジー社製、商品名「ＧＳＤ６００ＡＴ」、超音波の振幅：３０μｍ）とを接続してなる循環系にて滞留時間３０分間で循環させ、分散液を得た（分散処理ステップ）。 (Example 1)
<Dispersion process>
1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)-pentane (manufactured by 3M, product name Novec (registered 100 parts (100 g) of FFKM (manufactured by AGC, trade name "Aflas PM-3000") as a fluorine-containing elastomer is added to 1899 g of the product (trademark) 7300"), and the fluorine-containing elastomer is dissolved by stirring at a temperature of 20°C for 12 hours. to obtain a fluorine-containing elastomer solution (dissolution step).
Next, SGCNTs as carbon nanotubes (manufactured by Nippon Zeon Co., Ltd., product name “ZEONANO SG101”, average diameter: 3.5 nm, BET specific surface area: 1449 m 2 /g, t-plot above) were added to the fluorine-containing elastomer solution. Convex, carbon purity: 99.6%, mainly containing single-walled CNT) 2 parts (2 g), using a stirrer (PRIMIX, Lab Solution (registered trademark), stirring part: Homo Disper), It was stirred for 30 minutes at a temperature of 20°C. Furthermore, the obtained slurry was mixed with a holding tank and a bead mill (manufactured by Willie & Bakkofen, trade name "Dyno Mill Multilab", zirconia beads average diameter: 0.65 mm, peripheral speed 8 m / s) and an ultrasonic disperser (Sonic Technology Co., Ltd., trade name "GSD600AT", amplitude of ultrasonic waves: 30 μm) was circulated in a circulation system with a retention time of 30 minutes to obtain a dispersion (dispersion treatment step).
＜乾燥工程＞
　その後、得られた分散液を２０００ｇのアセトンへ滴下し、凝固させて黒色固体を得た。得られた黒色固体を１２０℃で１２時間減圧乾燥し、フッ素含有エラストマーとＳＧＣＮＴとの混合物を得た（乾燥工程）。 <Drying process>
After that, the resulting dispersion was added dropwise to 2000 g of acetone and solidified to obtain a black solid. The obtained black solid was dried under reduced pressure at 120° C. for 12 hours to obtain a mixture of the fluorine-containing elastomer and SGCNT (drying step).
＜混練工程＞
　５０℃のオープンロールを用い、前記混合物１０１部と、架橋剤としてのトリアリルイソシアヌレート（日本化成社製、製品名「ＴＡＩＣ（登録商標）」）３部及び２，５－ジメチル－２，５－ジ（ｔ－ブチルペルオキシ）ヘキサン（日本油脂社製、商品名「パーヘキサ（登録商標）２５Ｂ－４０」１部とを混練し、架橋性プレ組成物を得た（混練工程）。 <Kneading process>
Using an open roll at 50° C., 101 parts of the above mixture, 3 parts of triallyl isocyanurate (manufactured by Nippon Kasei Co., Ltd., product name “TAIC (registered trademark)”) as a cross-linking agent, and 2,5-dimethyl-2,5 -Di(t-butylperoxy)hexane (manufactured by NOF Corporation, trade name "Perhexa (registered trademark) 25B-40") was kneaded with 1 part to obtain a crosslinkable pre-composition (kneading step).
＜架橋工程＞
　得られた架橋性プレ組成物を金型に投入し、温度１５０℃、圧力１０ＭＰａで２０分間架橋させて、一次加硫後のシート状の架橋物（長さ：１５０ｍｍ、幅：１５０ｍｍ、厚さ：２ｍｍ）を得た。次いで、２５０℃のギヤ―オーブン（東洋精機社製、型式「Ｓ６０」）で４時間熱処理することで、エラストマー組成物として、二次加硫後のシート状の架橋物を得た。このエラストマー組成物を用いて、３７０℃で２時間加熱後のラジカル濃度、熱老化後の伸びを測定および評価した。結果を表１に示す。 <Crosslinking step>
The obtained crosslinkable pre-composition was put into a mold and crosslinked at a temperature of 150° C. and a pressure of 10 MPa for 20 minutes to obtain a crosslinked sheet after primary vulcanization (length: 150 mm, width: 150 mm, thickness : 2 mm). Then, heat treatment was performed for 4 hours in a gear oven (manufactured by Toyo Seiki Co., Ltd., model "S60") at 250°C to obtain a sheet-like crosslinked product after secondary vulcanization as an elastomer composition. Using this elastomer composition, the radical concentration after heating at 370° C. for 2 hours and the elongation after heat aging were measured and evaluated. Table 1 shows the results.
（実施例２）
　実施例１の分散工程において、カーボンナノチューブとして、ＳＧＣＮＴ２部（２ｇ）に代えて、ＭＷＣＮＴ（ＫＵＭＨＯ　ＰＥＴＲＯＣＨＥＭＩＣＡＬ社製、製品名「Ｋ－ｎａｎｏｓ　１００Ｐ」、ＢＥＴ比表面積：２５９ｍ２／ｇ、炭素純度：９４．１％）６部（６ｇ）を添加したこと以外は、実施例１と同様にして、分散工程、乾燥工程、混錬工程、および架橋工程を行い、得られたエラストマー組成物を用いて、３７０℃で２時間加熱後のラジカル濃度、熱老化後の伸びを測定および評価した。結果を表１に示す。 (Example 2)
In the dispersion step of Example 1, MWCNT (manufactured by KUMHO PETROCHEMICAL, product name “K-nanos 100P”, BET specific surface area: 259 m 2 /g, carbon purity: 94 instead of SGCNT 2 parts (2 g) as carbon nanotubes .1%) 6 parts (6 g) was added, and the dispersion step, drying step, kneading step, and cross-linking step were carried out in the same manner as in Example 1. Using the obtained elastomer composition, Radical concentration after heating at 370° C. for 2 hours and elongation after heat aging were measured and evaluated. Table 1 shows the results.
（実施例３）
　実施例１の分散工程において、分散液を得る際の分散処理条件として、ビーズミルの周速を８ｍ／ｓから１０ｍ／ｓに変更したこと以外は、実施例１と同様にして、分散工程、乾燥工程、混錬工程、および架橋工程を行い、得られたエラストマー組成物を用いて、３７０℃で２時間加熱後のラジカル濃度、熱老化後の伸びを測定および評価した。結果を表１に示す。 (Example 3)
In the dispersing step of Example 1, the dispersing step, the drying, and the After the steps, kneading step and cross-linking step were performed, the obtained elastomer composition was used to measure and evaluate the radical concentration after heating at 370° C. for 2 hours and the elongation after heat aging. Table 1 shows the results.
（比較例１）
　カーボンナノチューブとして、ＳＧＣＮＴ２部（２ｇ）に代えて、別のＳＷＣＮＴ（ＯＣＳｉＡｌ社製、製品名「ＴＵＢＡＬＬ」、ＢＥＴ比表面積：３９０ｍ２／ｇ、炭素純度：８１．４％）２部（２ｇ）を添加したこと以外は、実施例１と同様にして、分散工程、乾燥工程、混錬工程、および架橋工程を行い、得られたエラストマー組成物を用いて、３７０℃で２時間加熱後のラジカル濃度、熱老化後の伸びを測定および評価した。結果を表１に示す。 (Comparative example 1)
As carbon nanotubes, instead of SGCNT 2 parts (2 g), another SWCNT (manufactured by OCSiAl, product name “TUBALL”, BET specific surface area: 390 m 2 / g, carbon purity: 81.4%) 2 parts (2 g) The dispersion step, drying step, kneading step, and cross-linking step were carried out in the same manner as in Example 1 except that the addition of , the elongation after heat aging was measured and evaluated. Table 1 shows the results.
（比較例２）
　実施例１の分散工程において、分散液を得る際の分散処理条件として、超音波分散機を接続させず、ホールディングタンクとビーズミルとを接続してなる循環系を用いたこと以外は、実施例１と同様にして、分散工程、乾燥工程、混錬工程、および架橋工程を行い、得られたエラストマー組成物を用いて、３７０℃で２時間加熱後のラジカル濃度、熱老化後の伸びを測定および評価した。結果を表１に示す。 (Comparative example 2)
In the dispersion step of Example 1, as the dispersion treatment conditions for obtaining the dispersion liquid, the ultrasonic dispersing machine was not connected, except that a circulation system formed by connecting the holding tank and the bead mill was used. The dispersion step, drying step, kneading step, and cross-linking step were carried out in the same manner as in , and the obtained elastomer composition was used to measure the radical concentration after heating at 370 ° C. for 2 hours and the elongation after heat aging. evaluated. Table 1 shows the results.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１より、フッ素含有エラストマーと、カーボンナノチューブとを含み、３７０℃で２時間加熱後に電子スピン共鳴法により測定されるラジカル濃度が所定値以上である実施例１～３のエラストマー組成物は、上記ラジカル濃度が所定値に満たない比較例１～２のエラストマー組成物と比較して、耐熱性に優れていることが分かる。 From Table 1, it can be seen that the elastomer compositions of Examples 1 to 3, which contain a fluorine-containing elastomer and carbon nanotubes and have a radical concentration equal to or higher than a predetermined value as measured by an electron spin resonance method after being heated at 370° C. for 2 hours, It can be seen that the heat resistance is superior to that of the elastomer compositions of Comparative Examples 1 and 2, in which the radical concentration is less than the predetermined value.
　本発明によれば、耐熱性に優れたエラストマー組成物を提供することができる。 According to the present invention, an elastomer composition having excellent heat resistance can be provided.

Claims (6)

  1. 　フッ素含有エラストマーと、カーボンナノチューブとを含むエラストマー組成物であって、
    　３７０℃で２時間加熱後に電子スピン共鳴法により測定されるラジカル濃度が３×１０－７ｍｏｌ／ｇ以上である、エラストマー組成物。     An elastomer composition comprising a fluorine-containing elastomer and carbon nanotubes,
    An elastomer composition having a radical concentration of 3×10 −7 mol/g or more as measured by an electron spin resonance method after heating at 370° C. for 2 hours.
  2. 　前記カーボンナノチューブの炭素純度が９０質量％以上である、請求項１に記載のエラストマー組成物。 The elastomer composition according to claim 1, wherein the carbon nanotube has a carbon purity of 90% by mass or more.
  3. 　前記カーボンナノチューブが単層カーボンナノチューブを含有する、請求項１または２に記載のエラストマー組成物。 The elastomer composition according to claim 1 or 2, wherein the carbon nanotubes contain single-walled carbon nanotubes.
  4. 　前記カーボンナノチューブのＢＥＴ比表面積が６００ｍ２／ｇ以上である、請求項１または２に記載のエラストマー組成物。 3. The elastomer composition according to claim 1, wherein the carbon nanotubes have a BET specific surface area of 600 m <2> /g or more.
  5. 　前記カーボンナノチューブの含有量が、前記フッ素含有エラストマー１００質量部に対して、０．１質量部以上１０質量部以下である、請求項１または２に記載のエラストマー組成物。 The elastomer composition according to claim 1 or 2, wherein the content of the carbon nanotubes is 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the fluorine-containing elastomer.
  6. 　前記フッ素含有エラストマーが、四フッ化エチレン－パーフルオロアルキルビニルエーテル系ゴムを含有する、請求項１または２に記載のエラストマー組成物。 The elastomer composition according to claim 1 or 2, wherein the fluorine-containing elastomer contains tetrafluoroethylene-perfluoroalkyl vinyl ether rubber.
PCT/JP2023/005026 2022-02-24 2023-02-14 Elastomer composition WO2023162783A1 (en)

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WO2009102077A1 (en) * 2008-02-11 2009-08-20 The University Of Tokyo Carbon nanotube rubber composition, wiring, electroconductive paste, electronic circuit, and process for producing the carbon nanotube rubber composition
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JP2013023575A (en) * 2011-07-21 2013-02-04 Nissin Kogyo Co Ltd Sealing member and method for producing the same
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